mariadb/mysql-test/main/lock_multi.result

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drop table if exists t1,t2;
drop DATABASE if exists mysqltest_1;
connect locker,localhost,root,,;
connect locker2,localhost,root,,;
connect reader,localhost,root,,;
connect writer,localhost,root,,;
connection locker;
Cleanup after last merge client/mysqltest.c: Don't write error message to log if there is more than one possible error message include/mysqld_error.h: Made error messages more general libmysqld/Makefile.am: md5 is now in mysys mysql-test/include/have_isam.inc: Update to new result format mysql-test/include/not_embedded.inc: Update to new result format mysql-test/mysql-test-run.sh: Update to new result format mysql-test/r/auto_increment.result: Update to new result format mysql-test/r/count_distinct2.result: Update to new result format mysql-test/r/create.result: Update to new result format mysql-test/r/func_system.result: Update to new result format mysql-test/r/isam.result: Update to new result format mysql-test/r/lock.result: Update to new result format mysql-test/r/lock_multi.result: Update to new result format mysql-test/r/rename.result: Update to new result format mysql-test/r/rpl000001.result: Fix wrong test mysql-test/r/tablelock.result: Update to new result format mysql-test/t/rename.test: Update to new result format sql/share/czech/errmsg.txt: Made error messages more general sql/share/danish/errmsg.txt: Made error messages more general sql/share/dutch/errmsg.txt: Made error messages more general sql/share/english/errmsg.txt: Made error messages more general sql/share/estonian/errmsg.txt: Made error messages more general sql/share/french/errmsg.txt: Made error messages more general sql/share/german/errmsg.txt: Made error messages more general sql/share/greek/errmsg.txt: Made error messages more general sql/share/hungarian/errmsg.txt: Made error messages more general sql/share/italian/errmsg.txt: Made error messages more general sql/share/japanese/errmsg.txt: Made error messages more general sql/share/korean/errmsg.txt: Made error messages more general sql/share/norwegian-ny/errmsg.txt: Made error messages more general sql/share/norwegian/errmsg.txt: Made error messages more general sql/share/polish/errmsg.txt: Made error messages more general sql/share/portuguese/errmsg.txt: Made error messages more general sql/share/romanian/errmsg.txt: Made error messages more general sql/share/russian/errmsg.txt: Made error messages more general sql/share/slovak/errmsg.txt: Made error messages more general sql/share/spanish/errmsg.txt: Made error messages more general sql/share/swedish/errmsg.txt: Made error messages more general sql/share/ukrainian/errmsg.txt: Made error messages more general sql/sql_lex.cc: We can't remove lex->thd because sql_yacc uses it. sql/sql_lex.h: We can't remove lex->thd because sql_yacc uses it. sql/sql_yacc.yy: Cleanup support-files/mysql.spec.sh: Create MySQL-embedded rpm tools/mysqlmanager.c: Fix bug in merge
2001-10-08 06:24:04 +02:00
create table t1(n int);
insert into t1 values (1);
connection locker2;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
select get_lock("mysqltest_lock", 100);
get_lock("mysqltest_lock", 100)
1
connection locker;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
update t1 set n = 2 and get_lock('mysqltest_lock', 100);
connection writer;
update low_priority t1 set n = 4;
connection reader;
select n from t1;
connection locker2;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
select release_lock("mysqltest_lock");
release_lock("mysqltest_lock")
1
connection locker;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
select release_lock("mysqltest_lock");
release_lock("mysqltest_lock")
1
connection writer;
connection reader;
Updated manual about embedded version. Speed up column-completion in 'mysql' Don't use ISAM if HAVE_ISAM is not defined A lot of fixes for the embedded version. All libraries are now included in libmysqld.a Changed arguments to convert_dirname() to make it more general. Renamed files in the 'merge' directory to all use a common prefix. Don't compile both assembler and C functions on x86 BitKeeper/deleted/.del-mf_pack2.c~f07795bbcf57be7: Delete: mysys/mf_pack2.c Docs/manual.texi: Updated chapter about embedded version acinclude.m4: Fix for using BDB and InnoDB with embedded client/completion_hash.cc: Speed up memory allocation client/completion_hash.h: Speed up memory allocation client/mysql.cc: Speed up memory allocation client/mysqldump.c: Fix to use now convert_dirname client/mysqltest.c: Fixed memory allocation bugs. Added --basedir=#, --compress=#, --server-arg, --server-file. Fixes for embedded version Changed silent mode to -s instead of -q include/my_global.h: Update to use HAVE_ISAM include/my_sys.h: Cleanup of fn_format() include/mysql.h: Prepare FIELD struct for 4.1 include/mysql_embed.h: Don't use ISAM in embedded version innobase/include/srv0srv.h: Make InnoDB startup/shutdown silent in embedded version innobase/log/log0log.c: Make InnoDB startup/shutdown silent in embedded version innobase/srv/srv0srv.c: Make InnoDB startup/shutdown silent in embedded version innobase/srv/srv0start.c: Make InnoDB startup/shutdown silent in embedded version isam/isamlog.c: new convert_dirname libmysql/libmysql.c: Prepare for 4.1 libmysqld/Makefile.am: Changed to create one libmysqld.a file that includes all other libraries. libmysqld/examples/Makefile.am: Changed to use new libmysqld.a libmysqld/examples/test-run: Lot's of fixes to get new mysqltest with embedded MySQL to work. libmysqld/lib_sql.cc: Changed type of arguments for mysql_server_init() to make code more portable. libmysqld/libmysqld.c: Cleanup merge/Makefile.am: Rename to use common prefix. merge/mrg_close.c: Rename to use common prefix. merge/mrg_create.c: Rename to use common prefix. merge/mrg_def.h: Rename to use common prefix. merge/mrg_delete.c: Rename to use common prefix. merge/mrg_extra.c: Rename to use common prefix. merge/mrg_info.c: Rename to use common prefix. merge/mrg_locking.c: Rename to use common prefix. merge/mrg_open.c: Rename to use common prefix. merge/mrg_panic.c: Rename to use common prefix. merge/mrg_rrnd.c: Rename to use common prefix. merge/mrg_rsame.c: Rename to use common prefix. merge/mrg_static.c: Rename to use common prefix. merge/mrg_update.c: Rename to use common prefix. myisam/myisamlog.c: Use new convert_dirname myisammrg/Makefile.am: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_close.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_create.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_def.h: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_delete.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_extra.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_info.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_locking.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_open.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_panic.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_queue.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rfirst.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rkey.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rlast.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rnext.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rprev.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rrnd.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rsame.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_static.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_update.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_write.c: Renamed mymrgdef.h -> myrg_def.h mysql-test/include/master-slave.inc: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/mysql-test-run.sh: cleanup mysql-test/r/auto_increment.result: Cleanup of tests for embedded version mysql-test/r/func_system.result: Cleanup of tests for embedded version mysql-test/r/isam.result: Cleanup of tests for embedded version mysql-test/r/lock.result: Cleanup of tests for embedded version mysql-test/r/show_check.result: Cleanup of tests for embedded version mysql-test/t/auto_increment.test: Cleanup of tests for embedded version mysql-test/t/backup.test: Cleanup of tests for embedded version mysql-test/t/count_distinct2-master.opt: Cleanup of tests for embedded version mysql-test/t/count_distinct2.test: Cleanup of tests for embedded version mysql-test/t/create.test: Cleanup of tests for embedded version mysql-test/t/flush.test: Cleanup of tests for embedded version mysql-test/t/func_system.test: Cleanup of tests for embedded version mysql-test/t/isam.test: Cleanup of tests for embedded version mysql-test/t/kill.test: Cleanup of tests for embedded version mysql-test/t/lock.test: Cleanup of tests for embedded version mysql-test/t/order_fill_sortbuf-master.opt: Cleanup of tests for embedded version mysql-test/t/rpl000015.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/rpl000016.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/rpl000017.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/rpl000018.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/show_check.test: Move ISAM specific tests to isam.test mysql-test/t/status.test: Cleanup of tests for embedded version mysql-test/t/tablelock.test: Cleanup mysys/Makefile.am: Removed not used mf_pack2.c mysys/charset.c: new convert_dirname mysys/default.c: new convert_dirname mysys/mf_dirname.c: Changed convert_dirname() to be more general mysys/mf_format.c: Changed bit flags to fn_format() to defines. Added handling of relative filenames BitKeeper/etc/ignore: Added libmysqld/examples/test-gdbinit scripts/mysql_explain_log to the ignore list mysys/mf_pack.c: new convert_dirname mysys/mf_tempfile.c: new convert_dirname scripts/Makefile.am: Adde mysql_explain_log scripts/mysql_config.sh: Added support of --libmysqld-libs sql/Makefile.am: Fix to use 'innodb_system_libs' sql/ha_innobase.cc: Make InnoDB startup/shutdown silent in embedded version sql/ha_isam.cc: Added handling of HAVE_ISAM sql/ha_isammrg.cc: Added handling of HAVE_ISAM sql/ha_myisam.cc: Handle relative paths; Needed to support BACKUP TABLE in embedded version sql/ha_myisammrg.cc: Rename of filenames sql/handler.cc: Added handling of HAVE_ISAM sql/item_func.cc: Fix for ecc (Intel Compiler) sql/mysql_priv.h: Added global variable 'mysql_embedded' sql/mysqld.cc: Use HAVE_ISAM sql/sql_parse.cc: Use new convert_dirname sql/sql_select.cc: Fix for ecc (Intel Compiler) sql/sql_table.cc: Added handling of relative filenames strings/Makefile.am: Don't compile both assembler and C functions on x86 strings/bchange.c: cleanup
2001-10-08 03:58:07 +02:00
n
4
Cleanup after last merge client/mysqltest.c: Don't write error message to log if there is more than one possible error message include/mysqld_error.h: Made error messages more general libmysqld/Makefile.am: md5 is now in mysys mysql-test/include/have_isam.inc: Update to new result format mysql-test/include/not_embedded.inc: Update to new result format mysql-test/mysql-test-run.sh: Update to new result format mysql-test/r/auto_increment.result: Update to new result format mysql-test/r/count_distinct2.result: Update to new result format mysql-test/r/create.result: Update to new result format mysql-test/r/func_system.result: Update to new result format mysql-test/r/isam.result: Update to new result format mysql-test/r/lock.result: Update to new result format mysql-test/r/lock_multi.result: Update to new result format mysql-test/r/rename.result: Update to new result format mysql-test/r/rpl000001.result: Fix wrong test mysql-test/r/tablelock.result: Update to new result format mysql-test/t/rename.test: Update to new result format sql/share/czech/errmsg.txt: Made error messages more general sql/share/danish/errmsg.txt: Made error messages more general sql/share/dutch/errmsg.txt: Made error messages more general sql/share/english/errmsg.txt: Made error messages more general sql/share/estonian/errmsg.txt: Made error messages more general sql/share/french/errmsg.txt: Made error messages more general sql/share/german/errmsg.txt: Made error messages more general sql/share/greek/errmsg.txt: Made error messages more general sql/share/hungarian/errmsg.txt: Made error messages more general sql/share/italian/errmsg.txt: Made error messages more general sql/share/japanese/errmsg.txt: Made error messages more general sql/share/korean/errmsg.txt: Made error messages more general sql/share/norwegian-ny/errmsg.txt: Made error messages more general sql/share/norwegian/errmsg.txt: Made error messages more general sql/share/polish/errmsg.txt: Made error messages more general sql/share/portuguese/errmsg.txt: Made error messages more general sql/share/romanian/errmsg.txt: Made error messages more general sql/share/russian/errmsg.txt: Made error messages more general sql/share/slovak/errmsg.txt: Made error messages more general sql/share/spanish/errmsg.txt: Made error messages more general sql/share/swedish/errmsg.txt: Made error messages more general sql/share/ukrainian/errmsg.txt: Made error messages more general sql/sql_lex.cc: We can't remove lex->thd because sql_yacc uses it. sql/sql_lex.h: We can't remove lex->thd because sql_yacc uses it. sql/sql_yacc.yy: Cleanup support-files/mysql.spec.sh: Create MySQL-embedded rpm tools/mysqlmanager.c: Fix bug in merge
2001-10-08 06:24:04 +02:00
drop table t1;
connection locker;
Cleanup after last merge client/mysqltest.c: Don't write error message to log if there is more than one possible error message include/mysqld_error.h: Made error messages more general libmysqld/Makefile.am: md5 is now in mysys mysql-test/include/have_isam.inc: Update to new result format mysql-test/include/not_embedded.inc: Update to new result format mysql-test/mysql-test-run.sh: Update to new result format mysql-test/r/auto_increment.result: Update to new result format mysql-test/r/count_distinct2.result: Update to new result format mysql-test/r/create.result: Update to new result format mysql-test/r/func_system.result: Update to new result format mysql-test/r/isam.result: Update to new result format mysql-test/r/lock.result: Update to new result format mysql-test/r/lock_multi.result: Update to new result format mysql-test/r/rename.result: Update to new result format mysql-test/r/rpl000001.result: Fix wrong test mysql-test/r/tablelock.result: Update to new result format mysql-test/t/rename.test: Update to new result format sql/share/czech/errmsg.txt: Made error messages more general sql/share/danish/errmsg.txt: Made error messages more general sql/share/dutch/errmsg.txt: Made error messages more general sql/share/english/errmsg.txt: Made error messages more general sql/share/estonian/errmsg.txt: Made error messages more general sql/share/french/errmsg.txt: Made error messages more general sql/share/german/errmsg.txt: Made error messages more general sql/share/greek/errmsg.txt: Made error messages more general sql/share/hungarian/errmsg.txt: Made error messages more general sql/share/italian/errmsg.txt: Made error messages more general sql/share/japanese/errmsg.txt: Made error messages more general sql/share/korean/errmsg.txt: Made error messages more general sql/share/norwegian-ny/errmsg.txt: Made error messages more general sql/share/norwegian/errmsg.txt: Made error messages more general sql/share/polish/errmsg.txt: Made error messages more general sql/share/portuguese/errmsg.txt: Made error messages more general sql/share/romanian/errmsg.txt: Made error messages more general sql/share/russian/errmsg.txt: Made error messages more general sql/share/slovak/errmsg.txt: Made error messages more general sql/share/spanish/errmsg.txt: Made error messages more general sql/share/swedish/errmsg.txt: Made error messages more general sql/share/ukrainian/errmsg.txt: Made error messages more general sql/sql_lex.cc: We can't remove lex->thd because sql_yacc uses it. sql/sql_lex.h: We can't remove lex->thd because sql_yacc uses it. sql/sql_yacc.yy: Cleanup support-files/mysql.spec.sh: Create MySQL-embedded rpm tools/mysqlmanager.c: Fix bug in merge
2001-10-08 06:24:04 +02:00
create table t1(n int);
2013-08-20 13:48:29 +02:00
insert into t1 values (1),(2);
connection locker2;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
select get_lock("mysqltest_lock", 100);
get_lock("mysqltest_lock", 100)
1
connection locker;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
select n from t1 where get_lock('mysqltest_lock', 100);
connection writer;
update low_priority t1 set n = 4;
connection reader;
select n from t1;
Updated manual about embedded version. Speed up column-completion in 'mysql' Don't use ISAM if HAVE_ISAM is not defined A lot of fixes for the embedded version. All libraries are now included in libmysqld.a Changed arguments to convert_dirname() to make it more general. Renamed files in the 'merge' directory to all use a common prefix. Don't compile both assembler and C functions on x86 BitKeeper/deleted/.del-mf_pack2.c~f07795bbcf57be7: Delete: mysys/mf_pack2.c Docs/manual.texi: Updated chapter about embedded version acinclude.m4: Fix for using BDB and InnoDB with embedded client/completion_hash.cc: Speed up memory allocation client/completion_hash.h: Speed up memory allocation client/mysql.cc: Speed up memory allocation client/mysqldump.c: Fix to use now convert_dirname client/mysqltest.c: Fixed memory allocation bugs. Added --basedir=#, --compress=#, --server-arg, --server-file. Fixes for embedded version Changed silent mode to -s instead of -q include/my_global.h: Update to use HAVE_ISAM include/my_sys.h: Cleanup of fn_format() include/mysql.h: Prepare FIELD struct for 4.1 include/mysql_embed.h: Don't use ISAM in embedded version innobase/include/srv0srv.h: Make InnoDB startup/shutdown silent in embedded version innobase/log/log0log.c: Make InnoDB startup/shutdown silent in embedded version innobase/srv/srv0srv.c: Make InnoDB startup/shutdown silent in embedded version innobase/srv/srv0start.c: Make InnoDB startup/shutdown silent in embedded version isam/isamlog.c: new convert_dirname libmysql/libmysql.c: Prepare for 4.1 libmysqld/Makefile.am: Changed to create one libmysqld.a file that includes all other libraries. libmysqld/examples/Makefile.am: Changed to use new libmysqld.a libmysqld/examples/test-run: Lot's of fixes to get new mysqltest with embedded MySQL to work. libmysqld/lib_sql.cc: Changed type of arguments for mysql_server_init() to make code more portable. libmysqld/libmysqld.c: Cleanup merge/Makefile.am: Rename to use common prefix. merge/mrg_close.c: Rename to use common prefix. merge/mrg_create.c: Rename to use common prefix. merge/mrg_def.h: Rename to use common prefix. merge/mrg_delete.c: Rename to use common prefix. merge/mrg_extra.c: Rename to use common prefix. merge/mrg_info.c: Rename to use common prefix. merge/mrg_locking.c: Rename to use common prefix. merge/mrg_open.c: Rename to use common prefix. merge/mrg_panic.c: Rename to use common prefix. merge/mrg_rrnd.c: Rename to use common prefix. merge/mrg_rsame.c: Rename to use common prefix. merge/mrg_static.c: Rename to use common prefix. merge/mrg_update.c: Rename to use common prefix. myisam/myisamlog.c: Use new convert_dirname myisammrg/Makefile.am: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_close.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_create.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_def.h: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_delete.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_extra.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_info.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_locking.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_open.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_panic.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_queue.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rfirst.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rkey.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rlast.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rnext.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rprev.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rrnd.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_rsame.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_static.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_update.c: Renamed mymrgdef.h -> myrg_def.h myisammrg/myrg_write.c: Renamed mymrgdef.h -> myrg_def.h mysql-test/include/master-slave.inc: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/mysql-test-run.sh: cleanup mysql-test/r/auto_increment.result: Cleanup of tests for embedded version mysql-test/r/func_system.result: Cleanup of tests for embedded version mysql-test/r/isam.result: Cleanup of tests for embedded version mysql-test/r/lock.result: Cleanup of tests for embedded version mysql-test/r/show_check.result: Cleanup of tests for embedded version mysql-test/t/auto_increment.test: Cleanup of tests for embedded version mysql-test/t/backup.test: Cleanup of tests for embedded version mysql-test/t/count_distinct2-master.opt: Cleanup of tests for embedded version mysql-test/t/count_distinct2.test: Cleanup of tests for embedded version mysql-test/t/create.test: Cleanup of tests for embedded version mysql-test/t/flush.test: Cleanup of tests for embedded version mysql-test/t/func_system.test: Cleanup of tests for embedded version mysql-test/t/isam.test: Cleanup of tests for embedded version mysql-test/t/kill.test: Cleanup of tests for embedded version mysql-test/t/lock.test: Cleanup of tests for embedded version mysql-test/t/order_fill_sortbuf-master.opt: Cleanup of tests for embedded version mysql-test/t/rpl000015.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/rpl000016.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/rpl000017.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/rpl000018.test: Use short filenames for sockets (portability problem on Mac OS X) mysql-test/t/show_check.test: Move ISAM specific tests to isam.test mysql-test/t/status.test: Cleanup of tests for embedded version mysql-test/t/tablelock.test: Cleanup mysys/Makefile.am: Removed not used mf_pack2.c mysys/charset.c: new convert_dirname mysys/default.c: new convert_dirname mysys/mf_dirname.c: Changed convert_dirname() to be more general mysys/mf_format.c: Changed bit flags to fn_format() to defines. Added handling of relative filenames BitKeeper/etc/ignore: Added libmysqld/examples/test-gdbinit scripts/mysql_explain_log to the ignore list mysys/mf_pack.c: new convert_dirname mysys/mf_tempfile.c: new convert_dirname scripts/Makefile.am: Adde mysql_explain_log scripts/mysql_config.sh: Added support of --libmysqld-libs sql/Makefile.am: Fix to use 'innodb_system_libs' sql/ha_innobase.cc: Make InnoDB startup/shutdown silent in embedded version sql/ha_isam.cc: Added handling of HAVE_ISAM sql/ha_isammrg.cc: Added handling of HAVE_ISAM sql/ha_myisam.cc: Handle relative paths; Needed to support BACKUP TABLE in embedded version sql/ha_myisammrg.cc: Rename of filenames sql/handler.cc: Added handling of HAVE_ISAM sql/item_func.cc: Fix for ecc (Intel Compiler) sql/mysql_priv.h: Added global variable 'mysql_embedded' sql/mysqld.cc: Use HAVE_ISAM sql/sql_parse.cc: Use new convert_dirname sql/sql_select.cc: Fix for ecc (Intel Compiler) sql/sql_table.cc: Added handling of relative filenames strings/Makefile.am: Don't compile both assembler and C functions on x86 strings/bchange.c: cleanup
2001-10-08 03:58:07 +02:00
n
1
2013-08-20 13:48:29 +02:00
2
connection locker2;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
select release_lock("mysqltest_lock");
release_lock("mysqltest_lock")
1
connection locker;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
n
1
2013-08-20 13:48:29 +02:00
2
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
select release_lock("mysqltest_lock");
release_lock("mysqltest_lock")
1
connection writer;
Cleanup after last merge client/mysqltest.c: Don't write error message to log if there is more than one possible error message include/mysqld_error.h: Made error messages more general libmysqld/Makefile.am: md5 is now in mysys mysql-test/include/have_isam.inc: Update to new result format mysql-test/include/not_embedded.inc: Update to new result format mysql-test/mysql-test-run.sh: Update to new result format mysql-test/r/auto_increment.result: Update to new result format mysql-test/r/count_distinct2.result: Update to new result format mysql-test/r/create.result: Update to new result format mysql-test/r/func_system.result: Update to new result format mysql-test/r/isam.result: Update to new result format mysql-test/r/lock.result: Update to new result format mysql-test/r/lock_multi.result: Update to new result format mysql-test/r/rename.result: Update to new result format mysql-test/r/rpl000001.result: Fix wrong test mysql-test/r/tablelock.result: Update to new result format mysql-test/t/rename.test: Update to new result format sql/share/czech/errmsg.txt: Made error messages more general sql/share/danish/errmsg.txt: Made error messages more general sql/share/dutch/errmsg.txt: Made error messages more general sql/share/english/errmsg.txt: Made error messages more general sql/share/estonian/errmsg.txt: Made error messages more general sql/share/french/errmsg.txt: Made error messages more general sql/share/german/errmsg.txt: Made error messages more general sql/share/greek/errmsg.txt: Made error messages more general sql/share/hungarian/errmsg.txt: Made error messages more general sql/share/italian/errmsg.txt: Made error messages more general sql/share/japanese/errmsg.txt: Made error messages more general sql/share/korean/errmsg.txt: Made error messages more general sql/share/norwegian-ny/errmsg.txt: Made error messages more general sql/share/norwegian/errmsg.txt: Made error messages more general sql/share/polish/errmsg.txt: Made error messages more general sql/share/portuguese/errmsg.txt: Made error messages more general sql/share/romanian/errmsg.txt: Made error messages more general sql/share/russian/errmsg.txt: Made error messages more general sql/share/slovak/errmsg.txt: Made error messages more general sql/share/spanish/errmsg.txt: Made error messages more general sql/share/swedish/errmsg.txt: Made error messages more general sql/share/ukrainian/errmsg.txt: Made error messages more general sql/sql_lex.cc: We can't remove lex->thd because sql_yacc uses it. sql/sql_lex.h: We can't remove lex->thd because sql_yacc uses it. sql/sql_yacc.yy: Cleanup support-files/mysql.spec.sh: Create MySQL-embedded rpm tools/mysqlmanager.c: Fix bug in merge
2001-10-08 06:24:04 +02:00
drop table t1;
connection locker;
create table t1 (a int, b int);
create table t2 (c int, d int);
insert into t1 values(1,1);
insert into t1 values(2,2);
insert into t2 values(1,2);
lock table t1 read;
connection writer;
update t1,t2 set c=a where b=d;
connection reader;
select c from t2;
c
2
connection locker;
Backport of: ------------------------------------------------------------ revno: 2476.784.3 committer: davi@moksha.local timestamp: Tue 2007-10-02 21:27:31 -0300 message: Bug#25858 Some DROP TABLE under LOCK TABLES can cause deadlocks When a client (connection) holds a lock on a table and attempts to drop (obtain a exclusive lock) on a second table that is already held by a second client and the second client then attempts to drop the table that is held by the first client, leads to a circular wait deadlock. This scenario is very similar to trying to drop (or rename) a table while holding read locks and are correctly forbidden. The solution is to allow a drop table operation to continue only if the table being dropped is write (exclusively) locked, or if the table is temporary, or if the client is not holding any locks. Using this scheme prevents the creation of a circular chain in which each client is waiting for one table that the next client in the chain is holding. This is incompatible change, as can be seen by number of tests cases that needed to be fixed, but is consistent with respect to behavior of the different scenarios in which the circular wait might happen. mysql-test/r/drop.result: Test case result for Bug#25858 mysql-test/r/group_by.result: Fix test case result wrt drop table under lock tables -- unlock tables before dropping table. mysql-test/r/insert_notembedded.result: Fix test case result wrt drop table under lock tables -- unlock tables before dropping table mysql-test/r/lock.result: Fix test case result wrt drop table under lock tables -- unlock tables before dropping table. mysql-test/r/lock_multi.result: Fix test case result wrt drop table under lock tables -- unlock tables before dropping table. mysql-test/r/myisam.result: Fix test case result wrt drop table under lock tables -- unlock tables before dropping table. mysql-test/r/view.result: Fix test case result wrt drop table under lock tables -- unlock tables before dropping table. mysql-test/t/drop.test: Add test case for Bug#25858 mysql-test/t/group_by.test: Fix test case: unlock tables in preparation for a drop table. In some circumstances, dropping tables while holding locks leads to a deadlock. mysql-test/t/insert_notembedded.test: Fix test case: unlock tables in preparation for a drop table. In some circumstances, dropping tables while holding locks leads to a deadlock. mysql-test/t/lock.test: Fix test case: unlock tables in preparation for a drop table. In some circumstances, dropping tables while holding locks leads to a deadlock. mysql-test/t/lock_multi.test: Fix test case: unlock tables in preparation for a drop table. In some circumstances, dropping tables while holding locks leads to a deadlock. mysql-test/t/myisam.test: Fix test case: unlock tables in preparation for a drop table. In some circumstances, dropping tables while holding locks leads to a deadlock. mysql-test/t/query_cache_notembedded.test: Fix test case: unlock tables in preparation for a drop table. In some circumstances, dropping tables while holding locks leads to a deadlock. mysql-test/t/view.test: Fix test case: unlock tables in preparation for a drop table. In some circumstances, dropping tables while holding locks leads to a deadlock. sql/lock.cc: When trying to obtain a name lock under lock tables, ensure that the table is properly exclusively locked and fail otherwise.
2009-11-20 20:51:12 +01:00
unlock tables;
drop table t1;
drop table t2;
connection locker;
create table t1 (a int);
create table t2 (a int);
lock table t1 write, t2 write;
connection reader;
insert t1 select * from t2;
connection locker;
drop table t2;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
unlock tables;
connection reader;
Added SQLSTATE to client/server protocol bmove_allign -> bmove_align Added OLAP function ROLLUP Split mysql_fix_privilege_tables to a script and a .sql data file Added new (MEMROOT*) functions to avoid calling current_thd() when creating some common objects. Added table_alias_charset, for easier --lower-case-table-name handling Better SQL_MODE handling (Setting complex options also sets sub options) New (faster) assembler string functions for x86 BitKeeper/etc/ignore: added libmysqld/sql_state.c client/mysql.cc: Added SQLSTATE to error messages Added new function put_error() to be able to clean up some old code. client/mysqltest.c: Write ERROR SQLSTATE for all errors dbug/dbug.c: Portability fixes include/m_string.h: Rename bmove_allign as bmove_align include/mysql.h: Added SQLSTATE (for embedded version) include/mysql_com.h: Send correct SQLSTATE for the error to the client libmysql/libmysql.c: Changed default error state to HY000 Applied code cleanup patch libmysqld/Makefile.am: Added sql_state.cc libmysqld/libmysqld.c: Added sqlstate mysql-test/r/analyse.result: Updated results mysql-test/r/ansi.result: Updated results mysql-test/r/auto_increment.result: Updated results mysql-test/r/bdb-deadlock.result: Updated results mysql-test/r/bdb.result: Updated results mysql-test/r/comments.result: Updated results mysql-test/r/create.result: Updated results mysql-test/r/ctype_collate.result: Updated results mysql-test/r/delayed.result: Updated results mysql-test/r/delete.result: Updated results mysql-test/r/derived.result: Updated results mysql-test/r/distinct.result: Updated results mysql-test/r/drop.result: Updated results mysql-test/r/err000001.result: Updated results mysql-test/r/explain.result: Updated results mysql-test/r/flush.result: Updated results mysql-test/r/fulltext.result: Updated results mysql-test/r/func_gconcat.result: Updated results mysql-test/r/func_system.result: Updated results mysql-test/r/grant_cache.result: Updated results mysql-test/r/group_by.result: Updated results mysql-test/r/handler.result: Updated results mysql-test/r/heap.result: Updated results mysql-test/r/heap_btree.result: Updated results mysql-test/r/heap_hash.result: Updated results mysql-test/r/innodb.result: Updated results mysql-test/r/innodb_handler.result: Updated results mysql-test/r/insert_select.result: Updated results mysql-test/r/insert_update.result: Updated results mysql-test/r/join.result: Updated results mysql-test/r/join_outer.result: Updated results mysql-test/r/key.result: Updated results mysql-test/r/lock.result: Updated results mysql-test/r/lock_multi.result: Updated results mysql-test/r/merge.result: Updated results mysql-test/r/multi_update.result: Updated results mysql-test/r/myisam.result: Updated results mysql-test/r/null.result: Updated results mysql-test/r/olap.result: Updated results mysql-test/r/order_by.result: Updated results mysql-test/r/packet.result: Updated results mysql-test/r/query_cache.result: Updated results mysql-test/r/row.result: Updated results mysql-test/r/rpl000001.result: Updated results mysql-test/r/rpl000009.result: Updated results mysql-test/r/rpl_empty_master_crash.result: Updated results mysql-test/r/rpl_log.result: Updated results mysql-test/r/rpl_replicate_do.result: Updated results mysql-test/r/rpl_rotate_logs.result: Updated results mysql-test/r/select.result: Updated results mysql-test/r/select_safe.result: Updated results mysql-test/r/show_check.result: Updated results mysql-test/r/sql_mode.result: Updated results mysql-test/r/subselect.result: Updated results mysql-test/r/temp_table.result: Updated results mysql-test/r/truncate.result: Updated results mysql-test/r/type_blob.result: Updated results mysql-test/r/type_decimal.result: Updated results mysql-test/r/type_float.result: Updated results mysql-test/r/type_ranges.result: Updated results mysql-test/r/union.result: Updated results mysql-test/r/update.result: Updated results mysql-test/r/user_var.result: Updated results mysql-test/r/varbinary.result: Updated results mysql-test/r/variables.result: Updated results mysql-test/t/ansi.test: Test of sql_mode mysql-test/t/derived.test: Updated results mysql-test/t/func_system.test: Make this independen of the MySQL server name mysql-test/t/lowercase_table.test: Cleanup mysql-test/t/olap.test: A lot of new tests mysql-test/t/sql_mode.test: More test for sql_mode mysql-test/t/subselect.test: Added a few new tests (to find a bug in the item_ref code) scripts/Makefile.am: Added mysql_fix_privilege_tables.sql scripts/mysql_fix_privilege_tables.sh: Totally new script. This bascily just pipes mysql_fix_privilege_tables.sql through 'mysql' to 'mysqld' sql/Makefile.am: Added sql_state.cc sql/item.cc: Extended Item_field::eq() to be able to better match GROUP BY fields on the command line. Needed for ROLLUP sql/item.h: Added function to be able to avoid calling current_thd() when doing new Item. sql/item_sum.cc: Moved copy_or_same() and some reset() functions from item_sum.h Needed to be able to access thd->mem_root. sql/item_sum.h: Moved some functions to item_sum.cc Added make_unique() for ROLLUP sql/item_uniq.h: Fixed return value sql/mysql_priv.h: Updated MODE flags sql/mysqld.cc: Added ANSI as it's own mode Moved charset_info variables here Cleaned up handler_count handling (for NT) Added table_alias_charset, for easier --lower-case-table-name handling sql/net_serv.cc: New comment sql/protocol.cc: Send SQLSTATE to client sql/set_var.cc: Better SQL_MODE handling (Setting complex options also sets sub options) sql/set_var.h: Better SQL_MODE handling sql/sql_base.cc: Make alias depend on --lower-case-table-names Make find_item_in_list also check database name sql/sql_cache.cc: Indentation cleanup sql/sql_list.h: Added safety assert Addes support of alloc without current_thd() sql/sql_prepare.cc: Update after prototype change sql/sql_select.cc: Added ROLLUP sql/sql_select.h: structures for rollup sql/sql_show.cc: Easier SQL_MODE handling sql/sql_string.cc: Move CHARSET_INFO to mysqld (to be together with all other global variables) sql/sql_string.h: Added function to be able to avoid calling current_thd() when doing new Item. sql/sql_table.cc: Simpler --lower-case-table-name handling sql/sql_union.cc: Update after prototype change sql/sql_yacc.yy: ROLLUP sql/unireg.h: bmove_allign ->bmove_align strings/Makefile.am: Fix to be able to compile str_test.c strings/ctype.c: Removed empty lines strings/str_test.c: Added test of bmove_align strings/strings-x86.s: Faster bmove_align, bmove_upp and strmake strings/strings.asm: move_allg
2003-06-04 17:28:51 +02:00
ERROR 42S02: Table 'test.t2' doesn't exist
connection locker;
drop table t1;
connection locker;
Fixed compiler and valgrind warnings Added missing DBUG_xxx_RETURN statements Fixed some usage of not initialized variables (as found by valgrind) Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Note: valgrind still produces a lot of warnings about using not initialized code and shows memory loss errors when running the ndb tests BitKeeper/etc/ignore: added mysql-test/r/*.log client/mysqltest.c: Change type of variables to get rid of compiler warnings More debugging Fix memory leak mysql-test/mysql-test-run.sh: Collect warnings about missing DBUG_RETURN statements mysql-test/r/lock_multi.result: Add test of new code mysql-test/r/ndb_condition_pushdown.result: Drop used tables before test mysql-test/t/lock_multi.test: Add test of new code mysql-test/t/ndb_condition_pushdown.test: Drop used tables before test mysql-test/valgrind.supp: Ignore 'safe' warnings from libz (when used with archive) sql/event.cc: More comments Simplify code Fixed memory leak found by valgrind sql/ha_archive.cc: Remove compiler warnings (Wrong handlerton structure and signed/unsigned comparison) sql/ha_berkeley.cc: Fixed compiler warning sql/ha_blackhole.cc: Fixed compiler warning sql/ha_federated.cc: Fixed compiler warning sql/ha_heap.cc: Fixed compiler warning sql/ha_myisam.cc: Fixed compiler warning sql/ha_myisammrg.cc: Fixed compiler warning sql/ha_ndbcluster.cc: Fixed compiler warnings sql/ha_partition.cc: Fixed compiler warning Fixed error noticed by valgrind in ha_partition::rnd_init() sql/handler.cc: Fixed compiler warning sql/handler.h: Fixed compiler warning sql/item.cc: Fixed compiler warning sql/item_xmlfunc.cc: Fixed warning from valgrind when calling memcpy with wrong address sql/lock.cc: More debugging sql/log.cc: Fixed compiler warning Indentation fixes sql/log.h: Fixed compiler warning sql/mysql_priv.h: Changed prototype for 'drop_locked_tables' sql/opt_range.cc: Indentation fix sql/password.c: Removed compiler warnings sql/set_var.cc: Fixed compiler warning sql/slave.cc: Fixed compiler warning sql/sp_head.cc: Fixed compiler warning sql/sql_acl.cc: Fixed compiler warning sql/sql_analyse.cc: Added missing DBUG_RETURN statements sql/sql_base.cc: Removed de-reference of not initialized pointer More comments drop_locked_tables() changed to not delete tables used for name locking Fixed compiler warnings sql/sql_delete.cc: Fixed usage of not initialized variable (deleted could be referenced in some not common error conditions) sql/sql_parse.cc: Added missing DBUG_VOID_RETURN Simplify code sql/sql_partition.cc: Fixed usage of wrong variable (noticed by valgrind) sql/sql_plugin.cc: Removed compiler warning sql/sql_show.cc: Removed compiler warning sql/sql_table.cc: Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Fixed wrong test of 'table_type' (path_length could otherwise be accessed uninitialized) Remove compile warnings about not initialized variables. sql/sql_yacc.yy: Ensure that no_write_to_binlog is properly initialized (Was accessed uninitialized by partition code) sql/table.cc: Removed valgrind warnings (not fatal) Removed compiler warnings sql/tztime.cc: Removed valgrind warning storage/ndb/include/ndbapi/NdbIndexStat.hpp: Removed compiler warning
2006-03-29 13:27:36 +02:00
create table t1 (a int);
create table t2 (a int);
lock table t1 write, t2 write, t1 as t1_2 write, t2 as t2_2 write;
connection reader;
insert t1 select * from t2;
connection locker;
Fixed compiler and valgrind warnings Added missing DBUG_xxx_RETURN statements Fixed some usage of not initialized variables (as found by valgrind) Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Note: valgrind still produces a lot of warnings about using not initialized code and shows memory loss errors when running the ndb tests BitKeeper/etc/ignore: added mysql-test/r/*.log client/mysqltest.c: Change type of variables to get rid of compiler warnings More debugging Fix memory leak mysql-test/mysql-test-run.sh: Collect warnings about missing DBUG_RETURN statements mysql-test/r/lock_multi.result: Add test of new code mysql-test/r/ndb_condition_pushdown.result: Drop used tables before test mysql-test/t/lock_multi.test: Add test of new code mysql-test/t/ndb_condition_pushdown.test: Drop used tables before test mysql-test/valgrind.supp: Ignore 'safe' warnings from libz (when used with archive) sql/event.cc: More comments Simplify code Fixed memory leak found by valgrind sql/ha_archive.cc: Remove compiler warnings (Wrong handlerton structure and signed/unsigned comparison) sql/ha_berkeley.cc: Fixed compiler warning sql/ha_blackhole.cc: Fixed compiler warning sql/ha_federated.cc: Fixed compiler warning sql/ha_heap.cc: Fixed compiler warning sql/ha_myisam.cc: Fixed compiler warning sql/ha_myisammrg.cc: Fixed compiler warning sql/ha_ndbcluster.cc: Fixed compiler warnings sql/ha_partition.cc: Fixed compiler warning Fixed error noticed by valgrind in ha_partition::rnd_init() sql/handler.cc: Fixed compiler warning sql/handler.h: Fixed compiler warning sql/item.cc: Fixed compiler warning sql/item_xmlfunc.cc: Fixed warning from valgrind when calling memcpy with wrong address sql/lock.cc: More debugging sql/log.cc: Fixed compiler warning Indentation fixes sql/log.h: Fixed compiler warning sql/mysql_priv.h: Changed prototype for 'drop_locked_tables' sql/opt_range.cc: Indentation fix sql/password.c: Removed compiler warnings sql/set_var.cc: Fixed compiler warning sql/slave.cc: Fixed compiler warning sql/sp_head.cc: Fixed compiler warning sql/sql_acl.cc: Fixed compiler warning sql/sql_analyse.cc: Added missing DBUG_RETURN statements sql/sql_base.cc: Removed de-reference of not initialized pointer More comments drop_locked_tables() changed to not delete tables used for name locking Fixed compiler warnings sql/sql_delete.cc: Fixed usage of not initialized variable (deleted could be referenced in some not common error conditions) sql/sql_parse.cc: Added missing DBUG_VOID_RETURN Simplify code sql/sql_partition.cc: Fixed usage of wrong variable (noticed by valgrind) sql/sql_plugin.cc: Removed compiler warning sql/sql_show.cc: Removed compiler warning sql/sql_table.cc: Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Fixed wrong test of 'table_type' (path_length could otherwise be accessed uninitialized) Remove compile warnings about not initialized variables. sql/sql_yacc.yy: Ensure that no_write_to_binlog is properly initialized (Was accessed uninitialized by partition code) sql/table.cc: Removed valgrind warnings (not fatal) Removed compiler warnings sql/tztime.cc: Removed valgrind warning storage/ndb/include/ndbapi/NdbIndexStat.hpp: Removed compiler warning
2006-03-29 13:27:36 +02:00
drop table t2;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
unlock tables;
connection reader;
Fixed compiler and valgrind warnings Added missing DBUG_xxx_RETURN statements Fixed some usage of not initialized variables (as found by valgrind) Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Note: valgrind still produces a lot of warnings about using not initialized code and shows memory loss errors when running the ndb tests BitKeeper/etc/ignore: added mysql-test/r/*.log client/mysqltest.c: Change type of variables to get rid of compiler warnings More debugging Fix memory leak mysql-test/mysql-test-run.sh: Collect warnings about missing DBUG_RETURN statements mysql-test/r/lock_multi.result: Add test of new code mysql-test/r/ndb_condition_pushdown.result: Drop used tables before test mysql-test/t/lock_multi.test: Add test of new code mysql-test/t/ndb_condition_pushdown.test: Drop used tables before test mysql-test/valgrind.supp: Ignore 'safe' warnings from libz (when used with archive) sql/event.cc: More comments Simplify code Fixed memory leak found by valgrind sql/ha_archive.cc: Remove compiler warnings (Wrong handlerton structure and signed/unsigned comparison) sql/ha_berkeley.cc: Fixed compiler warning sql/ha_blackhole.cc: Fixed compiler warning sql/ha_federated.cc: Fixed compiler warning sql/ha_heap.cc: Fixed compiler warning sql/ha_myisam.cc: Fixed compiler warning sql/ha_myisammrg.cc: Fixed compiler warning sql/ha_ndbcluster.cc: Fixed compiler warnings sql/ha_partition.cc: Fixed compiler warning Fixed error noticed by valgrind in ha_partition::rnd_init() sql/handler.cc: Fixed compiler warning sql/handler.h: Fixed compiler warning sql/item.cc: Fixed compiler warning sql/item_xmlfunc.cc: Fixed warning from valgrind when calling memcpy with wrong address sql/lock.cc: More debugging sql/log.cc: Fixed compiler warning Indentation fixes sql/log.h: Fixed compiler warning sql/mysql_priv.h: Changed prototype for 'drop_locked_tables' sql/opt_range.cc: Indentation fix sql/password.c: Removed compiler warnings sql/set_var.cc: Fixed compiler warning sql/slave.cc: Fixed compiler warning sql/sp_head.cc: Fixed compiler warning sql/sql_acl.cc: Fixed compiler warning sql/sql_analyse.cc: Added missing DBUG_RETURN statements sql/sql_base.cc: Removed de-reference of not initialized pointer More comments drop_locked_tables() changed to not delete tables used for name locking Fixed compiler warnings sql/sql_delete.cc: Fixed usage of not initialized variable (deleted could be referenced in some not common error conditions) sql/sql_parse.cc: Added missing DBUG_VOID_RETURN Simplify code sql/sql_partition.cc: Fixed usage of wrong variable (noticed by valgrind) sql/sql_plugin.cc: Removed compiler warning sql/sql_show.cc: Removed compiler warning sql/sql_table.cc: Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Fixed wrong test of 'table_type' (path_length could otherwise be accessed uninitialized) Remove compile warnings about not initialized variables. sql/sql_yacc.yy: Ensure that no_write_to_binlog is properly initialized (Was accessed uninitialized by partition code) sql/table.cc: Removed valgrind warnings (not fatal) Removed compiler warnings sql/tztime.cc: Removed valgrind warning storage/ndb/include/ndbapi/NdbIndexStat.hpp: Removed compiler warning
2006-03-29 13:27:36 +02:00
ERROR 42S02: Table 'test.t2' doesn't exist
connection locker;
Fixed compiler and valgrind warnings Added missing DBUG_xxx_RETURN statements Fixed some usage of not initialized variables (as found by valgrind) Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Note: valgrind still produces a lot of warnings about using not initialized code and shows memory loss errors when running the ndb tests BitKeeper/etc/ignore: added mysql-test/r/*.log client/mysqltest.c: Change type of variables to get rid of compiler warnings More debugging Fix memory leak mysql-test/mysql-test-run.sh: Collect warnings about missing DBUG_RETURN statements mysql-test/r/lock_multi.result: Add test of new code mysql-test/r/ndb_condition_pushdown.result: Drop used tables before test mysql-test/t/lock_multi.test: Add test of new code mysql-test/t/ndb_condition_pushdown.test: Drop used tables before test mysql-test/valgrind.supp: Ignore 'safe' warnings from libz (when used with archive) sql/event.cc: More comments Simplify code Fixed memory leak found by valgrind sql/ha_archive.cc: Remove compiler warnings (Wrong handlerton structure and signed/unsigned comparison) sql/ha_berkeley.cc: Fixed compiler warning sql/ha_blackhole.cc: Fixed compiler warning sql/ha_federated.cc: Fixed compiler warning sql/ha_heap.cc: Fixed compiler warning sql/ha_myisam.cc: Fixed compiler warning sql/ha_myisammrg.cc: Fixed compiler warning sql/ha_ndbcluster.cc: Fixed compiler warnings sql/ha_partition.cc: Fixed compiler warning Fixed error noticed by valgrind in ha_partition::rnd_init() sql/handler.cc: Fixed compiler warning sql/handler.h: Fixed compiler warning sql/item.cc: Fixed compiler warning sql/item_xmlfunc.cc: Fixed warning from valgrind when calling memcpy with wrong address sql/lock.cc: More debugging sql/log.cc: Fixed compiler warning Indentation fixes sql/log.h: Fixed compiler warning sql/mysql_priv.h: Changed prototype for 'drop_locked_tables' sql/opt_range.cc: Indentation fix sql/password.c: Removed compiler warnings sql/set_var.cc: Fixed compiler warning sql/slave.cc: Fixed compiler warning sql/sp_head.cc: Fixed compiler warning sql/sql_acl.cc: Fixed compiler warning sql/sql_analyse.cc: Added missing DBUG_RETURN statements sql/sql_base.cc: Removed de-reference of not initialized pointer More comments drop_locked_tables() changed to not delete tables used for name locking Fixed compiler warnings sql/sql_delete.cc: Fixed usage of not initialized variable (deleted could be referenced in some not common error conditions) sql/sql_parse.cc: Added missing DBUG_VOID_RETURN Simplify code sql/sql_partition.cc: Fixed usage of wrong variable (noticed by valgrind) sql/sql_plugin.cc: Removed compiler warning sql/sql_show.cc: Removed compiler warning sql/sql_table.cc: Ensure that we don't remove locked tables used as name locks from open table cache until unlock_table_names() are called. This was fixed by having drop_locked_name() returning any table used as a name lock so that we can free it in unlock_table_names() This will allow Tomas to continue with his work to use namelocks to syncronize things. Fixed wrong test of 'table_type' (path_length could otherwise be accessed uninitialized) Remove compile warnings about not initialized variables. sql/sql_yacc.yy: Ensure that no_write_to_binlog is properly initialized (Was accessed uninitialized by partition code) sql/table.cc: Removed valgrind warnings (not fatal) Removed compiler warnings sql/tztime.cc: Removed valgrind warning storage/ndb/include/ndbapi/NdbIndexStat.hpp: Removed compiler warning
2006-03-29 13:27:36 +02:00
drop table t1;
End of 4.1 tests
create table t1(a int);
lock tables t1 write;
connection reader;
show columns from t1;
Field Type Null Key Default Extra
a int(11) YES NULL
connection locker;
unlock tables;
drop table t1;
connection locker;
USE mysql;
LOCK TABLES columns_priv WRITE, db WRITE, user WRITE;
FLUSH TABLES;
connection reader;
USE mysql;
SELECT global_priv.host FROM global_priv, db WHERE global_priv.user = db.user LIMIT 1;
connection locker;
OPTIMIZE TABLES columns_priv, db, global_priv;
Table Op Msg_type Msg_text
mysql.columns_priv optimize status OK
mysql.db optimize status OK
mysql.global_priv optimize status OK
UNLOCK TABLES;
connection reader;
host
localhost
USE test;
connection locker;
use test;
connection default;
connection writer;
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
CREATE TABLE t1 (c1 int);
LOCK TABLE t1 WRITE;
connection locker;
FLUSH TABLES WITH READ LOCK;
connection writer;
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
CREATE TABLE t2 (c1 int);
ERROR HY000: Table 't2' was not locked with LOCK TABLES
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
UNLOCK TABLES;
connection locker;
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
UNLOCK TABLES;
connection default;
DROP TABLE t1;
connection writer;
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
CREATE TABLE t1 (c1 int);
LOCK TABLE t1 WRITE;
connection locker;
FLUSH TABLES WITH READ LOCK;
connection writer;
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
CREATE TABLE t2 AS SELECT * FROM t1;
ERROR HY000: Table 't2' was not locked with LOCK TABLES
UNLOCK TABLES;
connection locker;
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
UNLOCK TABLES;
connection default;
Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. The stress test suite revealed some deadlocks. Some were related to the new condition variable (COND_global_read_lock) and some were general problems with the global read lock. It is now necessary to signal COND_global_read_lock whenever COND_refresh is signalled. We need to wait for the release of a global read lock if one is set before every operation that requires a write lock. But we must not wait if we have locked tables by LOCK TABLES. After setting a global read lock a thread waits until all write locks are released. mysql-test/r/lock_multi.result: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added test results. mysql-test/t/lock_multi.test: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added tests for possible deadlocks that did not occur with the stress test suite. mysys/thr_lock.c: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a protection against an infinite loop that occurs with the test case for Bug #20662. sql/lock.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). Added the definition of a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/mysql_priv.h: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Added a declaration for a new function that signals COND_global_read_lock whenever COND_refresh is signalled. sql/sql_base.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_handler.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh(). sql/sql_insert.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of INSERT DELAYED. It is handled on a higher level now. sql/sql_parse.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Wait for the release of a global read lock if one is set before every operation that requires a write lock. But don't wait if locked tables exist already. sql/sql_table.cc: Bug#16986 - Deadlock condition with MyISAM tables Addendum fixes after changing the condition variable for the global read lock. Removed global read lock handling from inside of CREATE TABLE. It is handled on a higher level now. Signal COND_global_read_lock whenever COND_refresh is signalled by using the new function broadcast_refresh().
2006-06-26 19:14:35 +02:00
DROP TABLE t1;
connect con1,localhost,root,,;
connect con2,localhost,root,,;
connection con1;
CREATE DATABASE mysqltest_1;
FLUSH TABLES WITH READ LOCK;
connection con2;
DROP DATABASE mysqltest_1;
connection con1;
DROP DATABASE mysqltest_1;
ERROR HY000: Can't execute the query because you have a conflicting read lock
UNLOCK TABLES;
connection con2;
connection default;
disconnect con1;
disconnect con2;
DROP DATABASE mysqltest_1;
ERROR HY000: Can't drop database 'mysqltest_1'; database doesn't exist
connection locker;
set sql_mode="";
create table t1 (f1 int(12) unsigned not null auto_increment, primary key(f1)) engine=innodb;
set sql_mode=default;
lock tables t1 write;
connection writer;
alter table t1 auto_increment=0;
connection reader;
alter table t1 auto_increment=0;
connection locker;
unlock tables;
connection writer;
connection reader;
connection locker;
drop table t1;
connect con1,localhost,root,,;
connect con2,localhost,root,,;
connect con3,localhost,root,,;
connect con4,localhost,root,,;
connect con5,localhost,root,,;
create table t1 (a int);
create table t2 like t1;
connection con1;
lock tables t1 write;
connection con2;
flush tables with read lock;
connection con5;
# global read lock is taken
connection con3;
select * from t2 for update;
connection con5;
# waiting for release of read lock
connection con4;
# would hang and later cause a deadlock
flush tables t2;
connection con1;
# clean up
unlock tables;
connection con2;
unlock tables;
connection con3;
a
connection con4;
connection default;
disconnect con5;
disconnect con4;
disconnect con3;
disconnect con2;
disconnect con1;
drop table t1,t2;
#
# Lightweight version:
# Ensure that the wait for a GRL is done before opening tables.
#
connect con1,localhost,root,,;
connect con2,localhost,root,,;
create table t1 (a int);
create table t2 like t1;
#
# UPDATE
#
connection default;
flush tables with read lock;
connection con1;
update t2 set a = 1;
connection default;
# statement is waiting for release of read lock
connection con2;
flush table t2;
connection default;
unlock tables;
connection con1;
connection con2;
#
# LOCK TABLES .. WRITE
#
connection default;
flush tables with read lock;
connection con1;
lock tables t2 write;
connection default;
# statement is waiting for release of read lock
connection con2;
flush table t2;
connection default;
unlock tables;
connection con1;
unlock tables;
connection default;
disconnect con2;
disconnect con1;
drop table t1,t2;
End of 5.0 tests
create table t1 (i int);
connection locker;
lock table t1 read;
connection writer;
update t1 set i= 10;
connection reader;
select * from t1;
connection default;
kill query ID;
connection reader;
i
connection writer;
ERROR 70100: Query execution was interrupted
connection locker;
unlock tables;
connection default;
drop table t1;
disconnect locker;
disconnect locker2;
disconnect reader;
disconnect writer;
drop table if exists t1;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
create table t1 (i int);
connect flush,localhost,root,,test,,;
connection default;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
lock tables t1 write;
connection flush;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
flush tables with read lock;;
connection default;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
alter table t1 add column j int;
connect insert,localhost,root,,test,,;
connection insert;
insert into t1 values (1,2);
connection default;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
unlock tables;
connection flush;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
select * from t1;
i j
unlock tables;
connection insert;
connection default;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
select * from t1;
i j
1 2
drop table t1;
disconnect flush;
disconnect insert;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
drop table if exists t1;
create table t1 (i int);
connect flush,localhost,root,,test,,;
connection default;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
lock tables t1 write;
connection flush;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
flush tables with read lock;;
connection default;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
flush tables;
unlock tables;
connection flush;
connection default;
disconnect flush;
Bug#32395 Alter table under a impending global read lock causes a server crash The problem is that some DDL statements (ALTER TABLE, CREATE TRIGGER, FLUSH TABLES, ...) when under LOCK TABLES need to momentarily drop the lock, reopen the table and grab the write lock again (using reopen_tables). When grabbing the lock again, reopen_tables doesn't pass a flag to mysql_lock_tables in order to ignore the impending global read lock, which causes a assertion because LOCK_open is being hold. Also dropping the lock must not signal to any threads that the table has been relinquished (related to the locking/flushing protocol). The solution is to correct the way the table is reopenned and the locks grabbed. When reopening the table and under LOCK TABLES, the table version should be set to 0 so other threads have to wait for the table. When grabbing the lock, any other flush should be ignored because it's theoretically a atomic operation. The chosen solution also fixes a potential discrepancy between binlog and GRL (global read lock) because table placeholders were being ignored, now a FLUSH TABLES WITH READ LOCK will properly for table with open placeholders. It's also important to mention that this patch doesn't fix a potential deadlock if one uses two GRLs under LOCK TABLES concurrently. mysql-test/r/lock_multi.result: Add test case result for Bug#32395 mysql-test/r/trigger_notembedded.result: Add test case result for Bug#32395 mysql-test/t/lock_multi.test: Add test case for Bug#32395 mysql-test/t/trigger_notembedded.test: Enable test case for Bug#32395 sql/ha_ndbcluster.cc: Update close_cached_tables usage. sql/ha_ndbcluster_binlog.cc: Update close_cached_tables usage. sql/mysql_priv.h: Update close_cache_tables prototype. sql/set_var.cc: Update close_cached_tables usage and set flag to wait for tables with placeholders. This is one of the places where a GRL can be obtained. sql/sql_base.cc: Preserve old version for write locked tables and ignore pending flushes and update close_cache_tables to take into account name locked tables. sql/sql_parse.cc: Update close_cached_tables usage and pass flag so that name locked tables are waited for. sql/sql_table.cc: Protect the table against a impending GRL if under LOCK TABLES.
2007-12-12 22:44:14 +01:00
drop table t1;
drop table if exists t1,t2;
create table t1 (a int);
flush status;
lock tables t1 read;
connect waiter,localhost,root,,;
connection waiter;
Backport of: ------------------------------------------------------------ revno: 3035.4.1 committer: Davi Arnaut <Davi.Arnaut@Sun.COM> branch nick: 39897-6.0 timestamp: Thu 2009-01-15 12:17:57 -0200 message: Bug#39897: lock_multi fails in pushbuild: timeout waiting for processlist The problem is that relying on the "Table lock" thread state in its current position to detect that a thread is waiting on a lock is race prone. The "Table lock" state change happens before the thread actually tries to grab a lock on a table. The solution is to move the "Table lock" state so that its set only when a thread is actually going to wait for a lock. The state change happens after the thread fails to grab the lock (because it is owned by other thread) and proceeds to wait on a condition. This is considered part of work related to WL#4284 "Transactional DDL locking" Warning: this patch contains an incompatible change. When waiting on a lock in thr_lock.c, the server used to display "Locked" processlist state. After this patch, the state is "Table lock". The new state was actually intended to be display since year 2002, when Monty added it. But up until removal of thd->locked boolean member, this state was ignored by SHOW PROCESSLIST code. mysql-test/r/lock_multi.result: A style fix. mysql-test/r/sp-threads.result: Changed output of SHOW PROCESSLIST (new wait state). mysql-test/t/lock_multi.test: Use a more accurate state description when waiting inside thr_lock.c. mysql-test/t/lock_sync.test: Use a more accurate state description when waiting inside thr_lock.c. mysql-test/t/multi_update.test: Use a more accurate state description when waiting inside thr_lock.c. mysql-test/t/query_cache_28249.test: Use a more accurate state description when waiting inside thr_lock.c. mysql-test/t/sp_notembedded.test: Use a more accurate state description when waiting inside thr_lock.c. mysql-test/t/status.test: Use a more accurate state description when waiting inside thr_lock.c. mysys/thr_lock.c: Update thread state while waiting for a table lock. sql/lock.cc: State change was moved inside thr_lock.c.
2009-12-03 21:08:27 +01:00
insert into t1 values(1);
connection default;
unlock tables;
connection waiter;
connection default;
drop table t1;
disconnect waiter;
select @tlwa < @tlwb;
@tlwa < @tlwb
1
End of 5.1 tests
drop table if exists t1;
create table t1 (i int);
connect flush,localhost,root,,test,,;
connection default;
lock tables t1 write;
connection flush;
flush tables with read lock;;
connection default;
flush tables;
drop table t1;
connection flush;
connection default;
disconnect flush;
2009-12-09 10:44:01 +01:00
#
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
# Test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock".
#
drop table if exists t1;
create table t1 (c1 int primary key, c2 int, c3 int);
insert into t1 values (1,1,0),(2,2,0),(3,3,0),(4,4,0),(5,5,0);
begin;
update t1 set c3=c3+1 where c2=3;
connect con46272,localhost,root,,test,,;
connection con46272;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
# The below ALTER TABLE statement should wait till transaction
# in connection 'default' is complete and then succeed.
# It should not deadlock or fail with ER_LOCK_DEADLOCK error.
# Sending:
alter table t1 add column c4 int;;
connection default;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
# Wait until the above ALTER TABLE gets blocked because this
# connection holds SW metadata lock on table to be altered.
# The below statement should succeed. It should not
# deadlock or end with ER_LOCK_DEADLOCK error.
update t1 set c3=c3+1 where c2=4;
# Unblock ALTER TABLE by committing transaction.
commit;
connection con46272;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
# Reaping ALTER TABLE.
connection default;
disconnect con46272;
Implement new type-of-operation-aware metadata locks. Add a wait-for graph based deadlock detector to the MDL subsystem. Fixes bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock" and bug #37346 "innodb does not detect deadlock between update and alter table". The first bug manifested itself as an unwarranted abort of a transaction with ER_LOCK_DEADLOCK error by a concurrent ALTER statement, when this transaction tried to repeat use of a table, which it has already used in a similar fashion before ALTER started. The second bug showed up as a deadlock between table-level locks and InnoDB row locks, which was "detected" only after innodb_lock_wait_timeout timeout. A transaction would start using the table and modify a few rows. Then ALTER TABLE would come in, and start copying rows into a temporary table. Eventually it would stumble on the modified records and get blocked on a row lock. The first transaction would try to do more updates, and get blocked on thr_lock.c lock. This situation of circular wait would only get resolved by a timeout. Both these bugs stemmed from inadequate solutions to the problem of deadlocks occurring between different locking subsystems. In the first case we tried to avoid deadlocks between metadata locking and table-level locking subsystems, when upgrading shared metadata lock to exclusive one. Transactions holding the shared lock on the table and waiting for some table-level lock used to be aborted too aggressively. We also allowed ALTER TABLE to start in presence of transactions that modify the subject table. ALTER TABLE acquires TL_WRITE_ALLOW_READ lock at start, and that block all writes against the table (naturally, we don't want any writes to be lost when switching the old and the new table). TL_WRITE_ALLOW_READ lock, in turn, would block the started transaction on thr_lock.c lock, should they do more updates. This, again, lead to the need to abort such transactions. The second bug occurred simply because we didn't have any mechanism to detect deadlocks between the table-level locks in thr_lock.c and row-level locks in InnoDB, other than innodb_lock_wait_timeout. This patch solves both these problems by moving lock conflicts which are causing these deadlocks into the metadata locking subsystem, thus making it possible to avoid or detect such deadlocks inside MDL. To do this we introduce new type-of-operation-aware metadata locks, which allow MDL subsystem to know not only the fact that transaction has used or is going to use some object but also what kind of operation it has carried out or going to carry out on the object. This, along with the addition of a special kind of upgradable metadata lock, allows ALTER TABLE to wait until all transactions which has updated the table to go away. This solves the second issue. Another special type of upgradable metadata lock is acquired by LOCK TABLE WRITE. This second lock type allows to solve the first issue, since abortion of table-level locks in event of DDL under LOCK TABLES becomes also unnecessary. Below follows the list of incompatible changes introduced by this patch: - From now on, ALTER TABLE and CREATE/DROP TRIGGER SQL (i.e. those statements that acquire TL_WRITE_ALLOW_READ lock) wait for all transactions which has *updated* the table to complete. - From now on, LOCK TABLES ... WRITE, REPAIR/OPTIMIZE TABLE (i.e. all statements which acquire TL_WRITE table-level lock) wait for all transaction which *updated or read* from the table to complete. As a consequence, innodb_table_locks=0 option no longer applies to LOCK TABLES ... WRITE. - DROP DATABASE, DROP TABLE, RENAME TABLE no longer abort statements or transactions which use tables being dropped or renamed, and instead wait for these transactions to complete. - Since LOCK TABLES WRITE now takes a special metadata lock, not compatible with with reads or writes against the subject table and transaction-wide, thr_lock.c deadlock avoidance algorithm that used to ensure absence of deadlocks between LOCK TABLES WRITE and other statements is no longer sufficient, even for MyISAM. The wait-for graph based deadlock detector of MDL subsystem may sometimes be necessary and is involved. This may lead to ER_LOCK_DEADLOCK error produced for multi-statement transactions even if these only use MyISAM: session 1: session 2: begin; update t1 ... lock table t2 write, t1 write; -- gets a lock on t2, blocks on t1 update t2 ... (ER_LOCK_DEADLOCK) - Finally, support of LOW_PRIORITY option for LOCK TABLES ... WRITE was abandoned. LOCK TABLE ... LOW_PRIORITY WRITE from now on has the same priority as the usual LOCK TABLE ... WRITE. SELECT HIGH PRIORITY no longer trumps LOCK TABLE ... WRITE in the wait queue. - We do not take upgradable metadata locks on implicitly locked tables. So if one has, say, a view v1 that uses table t1, and issues: LOCK TABLE v1 WRITE; FLUSH TABLE t1; -- (or just 'FLUSH TABLES'), an error is produced. In order to be able to perform DDL on a table under LOCK TABLES, the table must be locked explicitly in the LOCK TABLES list. mysql-test/include/handler.inc: Adjusted test case to trigger an execution path on which bug 41110 "crash with handler command when used concurrently with alter table" and bug 41112 "crash in mysql_ha_close_table/get_lock_data with alter table" were originally discovered. Left old test case which no longer triggers this execution path for the sake of coverage. Added test coverage for HANDLER SQL statements and type-aware metadata locks. Added a test for the global shared lock and HANDLER SQL. Updated tests to take into account that the old simple deadlock detection heuristics was replaced with a graph-based deadlock detector. mysql-test/r/debug_sync.result: Updated results (see debug_sync.test). mysql-test/r/handler_innodb.result: Updated results (see handler.inc test). mysql-test/r/handler_myisam.result: Updated results (see handler.inc test). mysql-test/r/innodb-lock.result: Updated results (see innodb-lock.test). mysql-test/r/innodb_mysql_lock.result: Updated results (see innodb_mysql_lock.test). mysql-test/r/lock.result: Updated results (see lock.test). mysql-test/r/lock_multi.result: Updated results (see lock_multi.test). mysql-test/r/lock_sync.result: Updated results (see lock_sync.test). mysql-test/r/mdl_sync.result: Updated results (see mdl_sync.test). mysql-test/r/sp-threads.result: SHOW PROCESSLIST output has changed due to the fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/r/truncate_coverage.result: Updated results (see truncate_coverage.test). mysql-test/suite/funcs_1/datadict/processlist_val.inc: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/funcs_1/r/processlist_val_no_prot.result: SELECT FROM I_S.PROCESSLIST output has changed due to fact that waiting for LOCK TABLES WRITE now happens within metadata locking subsystem. mysql-test/suite/rpl/t/rpl_sp.test: Updated to a new SHOW PROCESSLIST state name. mysql-test/t/debug_sync.test: Use LOCK TABLES READ instead of LOCK TABLES WRITE as the latter no longer allows to trigger execution path involving waiting on thr_lock.c lock and therefore reaching debug sync-point covered by this test. mysql-test/t/innodb-lock.test: Adjusted test case to the fact that innodb_table_locks=0 option is no longer supported, since LOCK TABLES WRITE handles all its conflicts within MDL subsystem. mysql-test/t/innodb_mysql_lock.test: Added test for bug #37346 "innodb does not detect deadlock between update and alter table". mysql-test/t/lock.test: Added test coverage which checks the fact that we no longer support DDL under LOCK TABLES on tables which were locked implicitly. Adjusted existing test cases accordingly. mysql-test/t/lock_multi.test: Added test for bug #46272 "MySQL 5.4.4, new MDL: unnecessary deadlock". Adjusted other test cases to take into account the fact that waiting for LOCK TABLES ... WRITE now happens within MDL subsystem. mysql-test/t/lock_sync.test: Since LOCK TABLES ... WRITE now takes SNRW metadata lock for tables locked explicitly we have to implicitly lock InnoDB tables (through view) to trigger the table-level lock conflict between TL_WRITE and TL_WRITE_ALLOW_WRITE. mysql-test/t/mdl_sync.test: Added basic test coverage for type-of-operation-aware metadata locks. Also covered with tests some use cases involving HANDLER statements in which a deadlock could arise. Adjusted existing tests to take type-of-operation-aware MDL into account. mysql-test/t/multi_update.test: Update to a new SHOW PROCESSLIST state name. mysql-test/t/truncate_coverage.test: Adjusted test case after making LOCK TABLES WRITE to wait until transactions that use the table to be locked are completed. Updated to the changed name of DEBUG_SYNC point. sql/handler.cc: Global read lock functionality has been moved into a class. sql/lock.cc: Global read lock functionality has been moved into a class. Updated code to use the new MDL API. sql/mdl.cc: Introduced new type-of-operation aware metadata locks. To do this: - Changed MDL_lock to use one list for waiting requests and one list for granted requests. For each list, added a bitmap that holds information what lock types a list contains. Added a helper class MDL_lock::List to manipulate with granted and waited lists while keeping the bitmaps in sync with list contents. - Changed lock-compatibility functions to use bitmaps that define compatibility. - Introduced a graph based deadlock detector inspired by waiting_threads.c from Maria implementation. - Now that we have a deadlock detector, and no longer have a global lock to protect individual lock objects, but rather use an rw lock per object, removed redundant code for upgrade, and the global read lock. Changed the MDL API to no longer require the caller to acquire the global intention exclusive lock by means of a separate method. Removed a few more methods that became redundant. - Removed deadlock detection heuristic, it has been made obsolete by the deadlock detector. - With operation-type-aware metadata locks, MDL subsystem has become aware of potential conflicts between DDL and open transactions. This made it possible to remove calls to mysql_abort_transactions_with_shared_lock() from acquisition paths for exclusive lock and lock upgrade. Now we can simply wait for these transactions to complete without fear of deadlock. Function mysql_lock_abort() has also become unnecessary for all conflicting cases except when a DDL conflicts with a connection that has an open HANDLER. sql/mdl.h: Introduced new type-of-operation aware metadata locks. Introduced a graph based deadlock detector and supporting methods. Added comments. God rid of redundant API calls. Renamed m_lt_or_ha_sentinel to m_trans_sentinel, since now it guards the global read lock as well as LOCK TABLES and HANDLER locks. sql/mysql_priv.h: Moved the global read lock functionality into a class. Added MYSQL_OPEN_FORCE_SHARED_MDL flag which forces open_tables() to take MDL_SHARED on tables instead of metadata locks specified in the parser. We use this to allow PREPARE run concurrently in presence of LOCK TABLES ... WRITE. Added signature for find_table_for_mdl_ugprade(). sql/set_var.cc: Global read lock functionality has been moved into a class. sql/sp_head.cc: When creating TABLE_LIST elements for prelocking or system tables set the type of request for metadata lock according to the operation that will be performed on the table. sql/sql_base.cc: - Updated code to use the new MDL API. - In order to avoid locks starvation we take upgradable locks all at once. As result implicitly locked tables no longer get an upgradable lock. Consequently DDL and FLUSH TABLES for such tables is prohibited. find_write_locked_table() was replaced by find_table_for_mdl_upgrade() function. open_table() was adjusted to return TABLE instance with upgradable ticket when necessary. - We no longer wait for all locks on OT_WAIT back off action -- only on the lock that caused the wait conflict. Moreover, now we distinguish cases when we have to wait due to conflict in MDL and old version of table in TDC. - Upate mysql_notify_threads_having_share_locks() to only abort thr_lock.c waits of threads that have open HANDLERs, since lock conflicts with only these threads now can lead to deadlocks not detectable by the MDL deadlock detector. - Remove mysql_abort_transactions_with_shared_locks() which is no longer needed. sql/sql_class.cc: Global read lock functionality has been moved into a class. Re-arranged code in THD::cleanup() to simplify assert. sql/sql_class.h: Introduced class to incapsulate global read lock functionality. Now sentinel in MDL subsystem guards the global read lock as well as LOCK TABLES and HANDLER locks. Adjusted code accordingly. sql/sql_db.cc: Global read lock functionality has been moved into a class. sql/sql_delete.cc: We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result TRUNCATE TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_handler.cc: Inform MDL_context about presence of open HANDLERs. Since HANLDERs break MDL protocol by acquiring table-level lock while holding only S metadata lock on a table MDL subsystem should take special care about such contexts (Now this is the only case when mysql_lock_abort() is used). sql/sql_parse.cc: Global read lock functionality has been moved into a class. Do not take upgradable metadata locks when opening tables for CREATE TABLE SELECT as it is not necessary and limits concurrency. When initializing TABLE_LIST objects before adding them to the table list set the type of request for metadata lock according to the operation that will be performed on the table. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result FLUSH TABLES is no longer allowed for such tables. sql/sql_prepare.cc: Use MYSQL_OPEN_FORCE_SHARED_MDL flag when opening tables during PREPARE. This allows PREPARE to run concurrently in presence of LOCK TABLES ... WRITE. sql/sql_rename.cc: Global read lock functionality has been moved into a class. sql/sql_show.cc: Updated code to use the new MDL API. sql/sql_table.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result DROP TABLE is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_trigger.cc: Global read lock functionality has been moved into a class. We no longer acquire upgradable metadata locks on tables which are locked by LOCK TABLES implicitly. As result CREATE/DROP TRIGGER is no longer allowed for such tables. Updated code to use the new MDL API. sql/sql_view.cc: Global read lock functionality has been moved into a class. Fixed results of wrong merge that led to misuse of GLR API. CREATE VIEW statement is not a commit statement. sql/table.cc: When resetting TABLE_LIST objects for PS or SP re-execution set the type of request for metadata lock according to the operation that will be performed on the table. Do the same in auxiliary function initializing metadata lock requests in a table list. sql/table.h: When initializing TABLE_LIST objects set the type of request for metadata lock according to the operation that will be performed on the table. sql/transaction.cc: Global read lock functionality has been moved into a class.
2010-02-01 12:43:06 +01:00
drop table t1;
#
2009-12-09 10:44:01 +01:00
# Bug#47249 assert in MDL_global_lock::is_lock_type_compatible
#
DROP TABLE IF EXISTS t1;
DROP VIEW IF EXISTS v1;
#
# Test 1: LOCK TABLES v1 WRITE, t1 READ;
#
CREATE TABLE t1 ( f1 integer );
CREATE VIEW v1 AS SELECT f1 FROM t1 ;
# Connection 2
2018-11-06 07:41:48 +01:00
connect con2,localhost,root;
2009-12-09 10:44:01 +01:00
LOCK TABLES v1 WRITE, t1 READ;
FLUSH TABLE t1;
2018-11-06 07:41:48 +01:00
disconnect con2;
# Connection 1
2018-11-06 07:41:48 +01:00
connection default;
LOCK TABLES t1 WRITE;
FLUSH TABLE t1;
2009-12-09 10:44:01 +01:00
DROP TABLE t1;
DROP VIEW v1;
#
# Test 2: LOCK TABLES t1 WRITE, v1 READ;
#
CREATE TABLE t1 ( f1 integer );
CREATE VIEW v1 AS SELECT f1 FROM t1 ;
connect con2,localhost,root;
2009-12-09 10:44:01 +01:00
LOCK TABLES t1 WRITE, v1 READ;
FLUSH TABLE t1;
disconnect con2;
connection default;
2009-12-09 10:44:01 +01:00
LOCK TABLES t1 WRITE;
FLUSH TABLE t1;
DROP TABLE t1;
DROP VIEW v1;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
#
# Test for bug #50913 "Deadlock between open_and_lock_tables_derived
# and MDL". Also see additional coverage in mdl_sync.test.
#
drop table if exists t1;
drop view if exists v1;
connect con50913,localhost,root;
connection default;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
create table t1 (i int);
create view v1 as select i from t1;
begin;
select * from t1;
i
connection con50913;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
# Sending:
alter table t1 add column j int;
connection default;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
# Wait until ALTER TABLE gets blocked.
# The below statement should try to acquire SW lock on 't1'
# and therefore should get ER_LOCK_DEADLOCK error. Before
# bug fix it acquired SR lock and hung on thr_lock.c lock.
delete a from t1 as a where i = 1;
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Unblock ALTER TABLE.
commit;
connection con50913;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
# Reaping ALTER TABLE;
connection default;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
begin;
select * from v1;
i
connection con50913;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
# Sending:
alter table t1 drop column j;
connection default;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
# Wait until ALTER TABLE gets blocked.
# The below statement should try to acquire SW lock on 't1'
# and therefore should get ER_LOCK_DEADLOCK error. Before
# bug fix it acquired SR lock and hung on thr_lock.c lock.
insert into v1 values (1);
ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
# Unblock ALTER TABLE.
commit;
connection con50913;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
# Reaping ALTER TABLE;
connection default;
disconnect con50913;
Fix for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". Concurrent execution of a multi-DELETE statement and ALTER TABLE statement which affected one of the tables used in the multi-DELETE sometimes led to deadlock. Similar deadlocks might have occured when one performed INSERT/UPDATE/DELETE on a view and concurrently executed ALTER TABLE for the view's underlying table, or when one concurrently executed TRUNCATE TABLE for InnoDB table and ALTER TABLE for the same table. These deadlocks were caused by a discrepancy between types of metadata and thr_lock.cc locks acquired by those statements. What happened was that multi-DELETE/TRUNCATE/DML-through-the- view statement in the first connection acquired SR lock on a table, then ALTER TABLE would come in in the second connection and acquire SNW metadata lock and TL_WRITE_ALLOW_READ thr_lock.c lock and then would start waiting for the first connection during lock upgrade. After that the statement in the first connection would try to acquire TL_WRITE lock on table and would start waiting for the second connection, creating a deadlock. This patch solves this problem by ensuring that we acquire SW metadata lock in all cases in which we acquiring write thr_lock.c lock. This guarantees that deadlocks like the one described above won't occur since all lock conflicts in such situation are resolved within MDL subsystem. This patch also adds assert which should guarantee that such situations won't arise in future. mysql-test/r/lock_multi.result: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/r/mdl_sync.result: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/lock_multi.test: Added main test for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". mysql-test/t/mdl_sync.test: Added additional coverage for bug #50913 "Deadlock between open_and_lock_tables_derived and MDL". sql/lock.cc: Added assert that enforces that when we are locking a non-temporary table we have an appropriate type of metadata lock on this table. sql/mysql_priv.h: Added separate flag for open_tables() to be able specify that SH metadata locks on table to be open should be acquired. We can no longer use MYSQL_LOCK_IGNORE_FLUSH flag for this as in addition to use in I_S implementation it is also used for opening system tables. Since in the latter case we also acquire thr_lock.c locks using SH metadata lock in it instead of SR or SW locks may lead to deadlock. sql/sql_base.cc: When opening tables don't interpret MYSQL_LOCK_IGNORE_FLUSH flag as request to acquire SH metadata locks. This flag is also used for opening system tables for which we also take thr_lock.c locks and thus proper metadata lock to take in this case is SR or SW lock (otherwise deadlocks can occur). In cases when SH lock is really required (e.g. when tables are open by I_S implementation) we rely on that newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag is used. sql/sql_delete.cc: mysql_truncate_by_delete(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_handler.cc: When closing table which was open by HANDLER statement clear TABLE::open_by_handler flag. This allows to use this flag as a reliable indication that TABLE instance was open by HANDLER statement in assert which was added to mysql_lock_tables(). sql/sql_parse.cc: multi_delete_set_locks_and_link_aux_tables(): Adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table list element from one which was set in parser to TL_WRITE. This removes discrepancy between types of these locks which allowed deadlocks to creep in. sql/sql_show.cc: Use newly introduced MYSQL_OPEN_FORCE_SHARED_HIGH_PRIO_MDL flag in order to acquire SH metadata locks when opening tables in I_S implementation. sql/sql_update.cc: Added comment explaining why in multi-update after deciding that we need weaker thr_lock.c lock on a table we don't downgrade metadata lock on it. sql/sql_view.cc: When merging view into main statement adjust type of metadata lock to be requested after changing type of thr_lock.c lock for table. This removes discrepancy between types of these locks which allowed deadlocks to creep in.
2010-02-08 21:19:55 +01:00
drop view v1;
drop table t1;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
#
# Bug#45225 Locking: hang if drop table with no timeout
#
# These tests also provide function coverage for the
# lock_wait_timeout server variable.
#
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (id int);
connect con2, localhost, root,,;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
SET SESSION lock_wait_timeout= 1;
#
# Test 1: acquire exclusive lock
#
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
START TRANSACTION;
INSERT INTO t1 VALUES (1);
connection con2;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
DROP TABLE t1;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
COMMIT;
#
# Test 2: upgrade shared lock
#
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
START TRANSACTION;
SELECT * FROM t1;
id
1
connection con2;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
ALTER TABLE t1 RENAME TO t2;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
COMMIT;
#
# Test 3: acquire shared lock
#
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
LOCK TABLE t1 WRITE;
connection con2;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
INSERT INTO t1(id) VALUES (2);
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
UNLOCK TABLES;
#
# Test 4: table level locks
#
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
LOCK TABLE t1 READ;
connection con2;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
INSERT INTO t1(id) VALUES(4);
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
UNLOCK TABLES;
#
# Test 5: Waiting on Table Definition Cache (TDC)
#
connect con3, localhost, root;
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
LOCK TABLE t1 READ;
connection con3;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
FLUSH TABLES;
# Sending:
FLUSH TABLES t1;
connection con2;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
SELECT * FROM t1;
ERROR HY000: Lock wait timeout exceeded; try restarting transaction
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
UNLOCK TABLES;
connection con3;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
# Reaping: FLUSH TABLES
#
# Test 6: Timeouts in I_S queries
#
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
CREATE TABLE t2 (id INT);
LOCK TABLE t2 WRITE;
connection con3;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
# Sending:
DROP TABLE t1, t2;
connection con2;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
SELECT table_name, table_comment FROM information_schema.tables
WHERE table_schema= 'test' AND table_name= 't1';
table_name table_comment
t1 Lock wait timeout exceeded; try restarting transaction
Warnings:
Warning 1205 Lock wait timeout exceeded; try restarting transaction
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
UNLOCK TABLES;
connection con3;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
# Reaping: DROP TABLE t1, t2
connection default;
Bug #45225 Locking: hang if drop table with no timeout This patch introduces timeouts for metadata locks. The timeout is specified in seconds using the new dynamic system variable "lock_wait_timeout" which has both GLOBAL and SESSION scopes. Allowed values range from 1 to 31536000 seconds (= 1 year). The default value is 1 year. The new server parameter "lock-wait-timeout" can be used to set the default value parameter upon server startup. "lock_wait_timeout" applies to all statements that use metadata locks. These include DML and DDL operations on tables, views, stored procedures and stored functions. They also include LOCK TABLES, FLUSH TABLES WITH READ LOCK and HANDLER statements. The patch also changes thr_lock.c code (table data locks used by MyISAM and other simplistic engines) to use the same system variable. InnoDB row locks are unaffected. One exception to the handling of the "lock_wait_timeout" variable is delayed inserts. All delayed inserts are executed with a timeout of 1 year regardless of the setting for the global variable. As the connection issuing the delayed insert gets no notification of delayed insert timeouts, we want to avoid unnecessary timeouts. It's important to note that the timeout value is used for each lock acquired and that one statement can take more than one lock. A statement can therefore block for longer than the lock_wait_timeout value before reporting a timeout error. When lock timeout occurs, ER_LOCK_WAIT_TIMEOUT is reported. Test case added to lock_multi.test. include/my_pthread.h: Added macros for comparing two timespec structs. include/thr_lock.h: Introduced timeouts for thr_lock.c locks. mysql-test/r/mysqld--help-notwin.result: Updated result file with the new server variable. mysql-test/r/mysqld--help-win.result: Updated result file with the new server variable. mysql-test/suite/sys_vars/r/lock_wait_timeout_basic.result: Added basic test for the new server variable. mysql-test/suite/sys_vars/t/lock_wait_timeout_basic.test: Added basic test for the new server variable. mysys/thr_lock.c: Introduced timeouts for thr_lock.c locks. sql/mdl.cc: Introduced timeouts for metadata locks. sql/mdl.h: Introduced timeouts for metadata locks. sql/sql_base.cc: Introduced timeouts in tdc_wait_for_old_versions(). sql/sql_class.h: Added new server variable lock_wait_timeout. sql/sys_vars.cc: Added new server variable lock_wait_timeout.
2010-02-11 11:23:39 +01:00
# Cleanup
disconnect con2;
disconnect con3;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
#
# Test for bug #51134 "Crash in MDL_lock::destroy on a concurrent
# DDL workload".
#
drop tables if exists t1, t2, t3;
connect con1, localhost, root, , ;
connect con2, localhost, root, , ;
connection default;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
create table t3 (i int);
connection con1;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
# Lock 't3' so upcoming RENAME is blocked.
lock table t3 read;
connection con2;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
# Remember ID for this connection.
# Start statement which will try to acquire two instances
# of X metadata lock on the same object.
# Sending:
rename tables t1 to t2, t2 to t3;;
connection default;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
# Wait until RENAME TABLE is blocked on table 't3'.
# Kill RENAME TABLE.
kill query ID;
connection con2;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
# RENAME TABLE should be aborted but should not crash.
ERROR 70100: Query execution was interrupted
connection con1;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
unlock tables;
connection default;
disconnect con1;
disconnect con2;
Fix for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". When a RENAME TABLE or LOCK TABLE ... WRITE statement which mentioned the same table several times were aborted during the process of acquring metadata locks (due to deadlock which was discovered or because of KILL statement) server might have crashed. When attempt to acquire all locks requested had failed we went through the list of requests and released locks which we have managed to acquire by that moment one by one. Since in the scenario described above list of requests contained duplicates this led to releasing the same ticket twice and a crash as result. This patch solves the problem by employing different approach to releasing locks in case of failure to acquire all locks requested. Now we take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad. mysql-test/r/lock_multi.result: Updated test results (see lock_multi.test). mysql-test/t/lock_multi.test: Added test case for bug #51134 "Crash in MDL_lock::destroy on a concurrent DDL workload". sql/mdl.cc: MDL_context::acquire_locks(): When attempt to acquire all locks requested has failed do not go through the list of requests and release locks which we have managed to acquire one by one. Since list of requests can contain duplicates such approach may lead to releasing the same ticket twice and a crash as result. Instead use the following approach - take a MDL savepoint before starting acquiring locks and simply rollback to it if things go bad.
2010-02-15 11:23:34 +01:00
drop table t3;
#
# Test for the bug where upgradable metadata locks was acquired
# even if the table to altered was temporary.
# Bug found while working on the related bug #51240.
#
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (id INT);
LOCK TABLE t1 WRITE;
connect con1, localhost, root;
CREATE TEMPORARY TABLE t1 (id INT);
ALTER TABLE t1 ADD COLUMN j INT;
connection default;
disconnect con1;
UNLOCK TABLES;
DROP TABLE t1;