PROBLEM:
When large number of connections are continuously made
with wait_timeout of 600 seconds for some hours, some
connections remain after wait_timeout expired and also
new connections get struck under the configuration and
the scenario reported in bug#16196591.
FIX:
The cause of this bug is the issue identified and fixed in
the BUG#16088658 in 5.6.Also LOCK_thread_count contention
issue fixed in BUG#15921866 in 5.6 need to be in 5.5 as
well. Since the issue is not reproducible, it has been
verified at customer configuration the issue could not
be reproduced after a 48-hour test with a non-debug build
which includes the above two fixes backported.
IF LOCALHOST IS BOTH IPV4/IPV6 ENABLED.
The original patch removed default value of the bind-address option.
So, the default value became NULL. By coincedence NULL resolves
to 0.0.0.0 and ::, and since the server chooses first IPv4-address,
0.0.0.0 is choosen. So, there was no change in the behaviour.
This patch restores default value of the bind-address option to "0.0.0.0".
MEMORY LEAK.
Background:
- There are caches for stored functions and stored procedures (SP-cache);
- There is no similar cache for events;
- Triggers are cached together with TABLE objects;
- Those SP-caches are per-session (i.e. specific to each session);
- A stored routine is represented by a sp_head-instance internally;
- SP-cache basically contains sp_head-objects of stored routines, which
have been executed in a session;
- sp_head-object is added into the SP-cache before the corresponding
stored routine is executed;
- SP-cache is flushed in the end of the session.
The problem was that SP-cache might grow without any limit. Although this
was not a pure memory leak (the SP-cache is flushed when session is closed),
this is still a problem, because the user might take much memory by
executing many stored routines.
The patch fixes this problem in the least-intrusive way. A soft limit
(similar to the size of table definition cache) is introduced. To represent
such limit the new runtime configuration parameter 'stored_program_cache'
is introduced. The value of this parameter is stored in the new global
variable stored_program_cache_size that used to control the size of SP-cache
to overflow.
The parameter 'stored_program_cache' limits number of cached routines for
each thread. It has the following min/default/max values given from support:
min = 256, default = 256, max = 512 * 1024.
Also it should be noted that this parameter limits the size of
each cache (for stored procedures and for stored functions) separately.
The SP-cache size is checked after top-level statement is parsed.
If SP-cache size exceeds the limit specified by parameter
'stored_program_cache' then SP-cache is flushed and memory allocated for
cache objects is freed. Such approach allows to flush cache safely
when there are dependencies among stored routines.
sql/mysqld.cc:
Added global variable stored_program_cache_size to store value of
configuration parameter 'stored-program-cache'.
sql/mysqld.h:
Added declaration of global variable stored_program_cache_size.
sql/sp_cache.cc:
Extended interface for sp_cache by adding helper routine
sp_cache_enforce_limit to control size of stored routines cache for
overflow. Also added method enforce_limit into class sp_cache that
implements control of cache size for overflow.
sql/sp_cache.h:
Extended interface for sp_cache by adding standalone routine
sp_cache_enforce_limit to control size of stored routines cache
for overflow.
sql/sql_parse.cc:
Added flush of sp_cache after processing of next sql-statement
received from a client.
sql/sql_prepare.cc:
Added flush of sp_cache after preparation/execution of next prepared
sql-statement received from a client.
sql/sys_vars.cc:
Added support for configuration parameter stored-program-cache.
Problem : The basic problem is the way the thread sleeps in mysql-5.5 and also in mysql-5.1
when we execute a stop slave on windows platform.
On windows platform if the stop slave is executed after the master dies, we have
this long wait before the stop slave return a value. This is because there is a
sleep of the thread. The sleep is uninterruptable in the two above version,
which was fixed by Davi patch for the BUG#11765860 for mysql-trunk. Backporting
his patch for mysql-5.5 fixes the problem.
Solution : A new pair of mutex and condition variable is introduced to synchronize thread
sleep and finalization. A new mutex is required because the slave threads are
terminated while holding the slave thread locks (run_lock), which can not be
relinquished during termination as this would affect the lock order.
mysql-test/suite/rpl/r/rpl_start_stop_slave.result:
The result file associated with the test added.
mysql-test/suite/rpl/t/rpl_start_stop_slave.test:
A test to check the new functionality.
sql/rpl_mi.cc:
The constructor using the new mutex and condition variables for the master_info.
sql/rpl_mi.h:
The condition variable and mutex have been added for the master_info.
sql/rpl_rli.cc:
The constructor using the new mutex and condition variables for the realy_log_info.
sql/rpl_rli.h:
The condition variable and mutex have been added for the relay_log_info.
sql/slave.cc:
Use a timed wait on a condition variable to implement a interruptible sleep.
The wait is registered with the THD object so that the thread will be woken
up if killed.
BIN LOG HAS BEEN MOVED
When moving the binary/relay log files from one location to
another and restarting the server with a different log-bin or
relay-log paths, would cause the startup process to abort. The
root cause was that the server would not be able to find the log
files because it would consider old paths for entries in the
index file instead of the new location. What's even worse, the
relative paths would not be considered relative to the path
provided in log-bin and relay-log, but to mysql_data_dir.
We fix the cases where the server contains relative paths. When
the server is reading from the index file, it checks whether the
entry contains relative paths. If it does, we replace it with the
absolute path set in log-bin/relay-log option. Absolute paths
remain unchanged and the index must be manually edited to
consider the new log-bin and/or relay-log path (this should be
documented). This is a fix for a GA version, that does not break
behavior (that much).
For development versions, we should go with Zhenxing's approach
that removes paths altogether from index files.
mysql-test/include/begin_include_file.inc:
Added parameter to keep the begin_include_file.inc silent. Useful when
including scripts that contain platform dependent parameters, for example:
--let $rpl_server_parameters=--log-bin=$tmpdir/slave-bin --relay-log=$tmpdir/slave-relay-bin
--let $keep_include_silent=1
source include/rpl_start_server.inc;
--let $keep_include_silent=0
We want the paths ($tmpdir/slave-bin and $tmpdir/slave-relay-bin) not to be in the
result file.
mysql-test/suite/rpl/t/rpl_binlog_index.test:
Test case.
sql/log.cc:
When finding the corresponding log entry in the index file, we first
normalize the paths before doing the comparison. This will make relative
paths to be turned into absolute paths (based on the opt_bin_logname or
opt_relay_logname) and then compared against also, expanded paths entered,
through CHANGE MASTER for instance.
sql/log.h:
Added normalize_binlog_name, which turns relative paths, into absolute paths
given the parameter: is_relay_log ? opt_relay_logname : opt_bin_logname .
sql/mysqld.cc:
Exposing opt_bin_logname.
sql/mysqld.h:
Exposing opt_bin_logname.
of service in prepared statements).
sql/sql_prepare.cc:
At mysql_stmt_get_longdata(): instead of pushing an internal
error handler (as done in 5.1-tree) we save, set and restore
the statement's diagnostics area and warning info.
@ mysql-test/r/ctype_latin1.result
@ mysql-test/r/ctype_utf8.result
@ mysql-test/t/ctype_latin1.test
@ mysql-test/t/ctype_utf8.test
Adding tests
@ sql/mysqld.h
@ sql/item.cc
@ sql/sql_parse.cc
@ sql/sql_view.cc
Refactoring (thanks to Guilhem for the idea):
Item_string::print() was hard to understand because of the different
QT_ constants: in "query_type==QT_x", QT_x is explicitely included
but the other two QT_ are implicitely excluded. The combinations
with '||' and '&&' make this even harder.
- logic is now more "explicit" by changing QT_ constants to a bitmap of flags:
QT_ORDINARY: no change,
QT_IS -> QT_TO_SYSTEM_CHARSET | QT_WITHOUT_INTRODUCERS,
QT_EXPLAIN -> QT_TO_SYSTEM_CHARSET
(QT_EXPLAIN was introduced in the first version of the Bug#57341 patch)
- Item_string::print() is rewritten using those flags
Bugfix itself:
When QT_TO_SYSTEM_CHARSET is used alone (with no QT_WITHOUT_INTRODUCERS),
we print string literals as follows:
- display introducers if they were in the original query
- print ASCII characters as is
- print non-ASCII characters using hex-escape
Note: as "EXPLAIN" output is only for human readability purposes
and does not need to be a pasrable SQL, so using hex-escape is Ok.
ErrConvString class perfectly suites for hex escaping purposes.
Before this fix, all the performance schema instrumentation for both the binary log
and the relay log would use the following instruments:
- wait/io/file/sql/binlog
- wait/io/file/sql/binlog_index
- wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_index
- wait/synch/cond/sql/MYSQL_BIN_LOG::update_cond
This instrumentation is too general and can be more specific.
With this fix, the binlog instrumentation is identical,
and the relay log instrumentation is changed to:
- wait/io/file/sql/relaylog
- wait/io/file/sql/relaylog_index
- wait/synch/mutex/sql/MYSQL_RELAY_LOG::LOCK_index
- wait/synch/cond/sql/MYSQL_RELAY_LOG::update_cond
With this change, the performance instrumentation for the binary log and the relay log,
which share the same structure but have different uses, is more detailed.
This is especially important for hosts in the middle of a replication chain,
that are both masters (binlog) and slaves (relaylog).
mysql-test/r/mysqld--help-notwin.result:
consequence of introducing opt_autocommit and its default
mysql-test/suite/sys_vars/r/autocommit_func4.result:
Before this fix, this test would have shown @@global.autocommit == 0
in spite of --autocommit=on.
mysql-test/suite/sys_vars/r/autocommit_func5.result:
result unchanged by the fix
sql/mysqld.cc:
atoi(argument) was reliable for =0|1 parameters. Now that boolean options
must support =on/off/true/false, atoi(argument) is wrong (being always 0
for those strings). Instead, let the internal logic of my_getopt
(in particular get_bool_argument()) set a boolean opt_autocommit
properly, and use that to set global_system_variables.option_bits.
The problem is a race between a session closing its vio
(i.e. after a COM_QUIT) at the same time it is being killed by
another thread. This could trigger a assertion in vio_close()
as the two threads could end up closing the same vio, at the
same time. This could happen due to the implementation of
SIGNAL_WITH_VIO_CLOSE, which closes the vio of the thread
being killed.
The solution is to serialize the close of the Vio under
LOCK_thd_data, which protects THD data.
No regression test is added as this is essentially a debug
issue and the test case would be quite convoluted as we would
need to synchronize a session that is being killed -- which
is a bit difficult since debug sync points code does not
synchronize killed sessions.
sql/mysqld.cc:
Drop lock parameter from close_connection, its not necessary
any more. The newly introduced THD::disconnect method will take
care of locking.
sql/mysqld.h:
Change prototype, add a default parameter for the error code.
sql/sql_class.cc:
In case SIGNAL_WITH_VIO_CLOSE is defined, the active vio is
closed and cleared. Subsequent calls will only close the vio
owned by the session.
Before this fix, file io for the binary log file was not accounted properly,
and showed no io at all.
This bug was due to the following issues:
1) file io for the binlog was instrumented:
- sometime as "wait/io/file/sql/binlog"
- sometime as "wait/io/file/sql/MYSQL_LOG"
leading to inconsistent event_names.
2) the binlog file itself was using an IO_CACHE,
but the IO_CACHE implementation in mysys/mf_iocache.c was
not instrumented to make performance schema calls to record file io.
3) The "wait/io/file/sql/MYSQL_LOG" instrumentation was used
for several log files, such as:
- the binary log
- the slow log
- the query log
which caused file io in these different log files to be accounted
against the same instrument.
The instrumentation needs to have a finer grain and report io
in different event_names, because each file really serves a different purpose.
With this fix:
- the IO_CACHE implementation is now instrumented
- the "wait/io/file/sql/MYSQL_LOG" instrument has been removed
- binlog io is now always instrumented with "wait/io/file/sql/binlog"
- the slow log is instrumented with a new name, "wait/io/file/sql/slow_log"
- the query log is instrumented with a new name, "wait/io/file/sql/query_log"
bug #57006 "Deadlock between HANDLER and FLUSH TABLES WITH READ
LOCK" and bug #54673 "It takes too long to get readlock for
'FLUSH TABLES WITH READ LOCK'".
The first bug manifested itself as a deadlock which occurred
when a connection, which had some table open through HANDLER
statement, tried to update some data through DML statement
while another connection tried to execute FLUSH TABLES WITH
READ LOCK concurrently.
What happened was that FTWRL in the second connection managed
to perform first step of GRL acquisition and thus blocked all
upcoming DML. After that it started to wait for table open
through HANDLER statement to be flushed. When the first connection
tried to execute DML it has started to wait for GRL/the second
connection creating deadlock.
The second bug manifested itself as starvation of FLUSH TABLES
WITH READ LOCK statements in cases when there was a constant
stream of concurrent DML statements (in two or more
connections).
This has happened because requests for protection against GRL
which were acquired by DML statements were ignoring presence of
pending GRL and thus the latter was starved.
This patch solves both these problems by re-implementing GRL
using metadata locks.
Similar to the old implementation acquisition of GRL in new
implementation is two-step. During the first step we block
all concurrent DML and DDL statements by acquiring global S
metadata lock (each DML and DDL statement acquires global IX
lock for its duration). During the second step we block commits
by acquiring global S lock in COMMIT namespace (commit code
acquires global IX lock in this namespace).
Note that unlike in old implementation acquisition of
protection against GRL in DML and DDL is semi-automatic.
We assume that any statement which should be blocked by GRL
will either open and acquires write-lock on tables or acquires
metadata locks on objects it is going to modify. For any such
statement global IX metadata lock is automatically acquired
for its duration.
The first problem is solved because waits for GRL become
visible to deadlock detector in metadata locking subsystem
and thus deadlocks like one in the first bug become impossible.
The second problem is solved because global S locks which
are used for GRL implementation are given preference over
IX locks which are acquired by concurrent DML (and we can
switch to fair scheduling in future if needed).
Important change:
FTWRL/GRL no longer blocks DML and DDL on temporary tables.
Before this patch behavior was not consistent in this respect:
in some cases DML/DDL statements on temporary tables were
blocked while in others they were not. Since the main use cases
for FTWRL are various forms of backups and temporary tables are
not preserved during backups we have opted for consistently
allowing DML/DDL on temporary tables during FTWRL/GRL.
Important change:
This patch changes thread state names which are used when
DML/DDL of FTWRL is waiting for global read lock. It is now
either "Waiting for global read lock" or "Waiting for commit
lock" depending on the stage on which FTWRL is.
Incompatible change:
To solve deadlock in events code which was exposed by this
patch we have to replace LOCK_event_metadata mutex with
metadata locks on events. As result we have to prohibit
DDL on events under LOCK TABLES.
This patch also adds extensive test coverage for interaction
of DML/DDL and FTWRL.
Performance of new and old global read lock implementations
in sysbench tests were compared. There were no significant
difference between new and old implementations.
mysql-test/include/check_ftwrl_compatible.inc:
Added helper script which allows to check that a statement is
compatible with FLUSH TABLES WITH READ LOCK.
mysql-test/include/check_ftwrl_incompatible.inc:
Added helper script which allows to check that a statement is
incompatible with FLUSH TABLES WITH READ LOCK.
mysql-test/include/handler.inc:
Adjusted test case to the fact that now DROP TABLE closes
open HANDLERs for the table to be dropped before checking
if there active FTWRL in this connection.
mysql-test/include/wait_show_condition.inc:
Fixed small error in the timeout message. The correct name
of variable used as parameter for this script is "$condition"
and not "$wait_condition".
mysql-test/r/delayed.result:
Added test coverage for scenario which triggered assert in
metadata locking subsystem.
mysql-test/r/events_2.result:
Updated test results after prohibiting event DDL operations
under LOCK TABLES.
mysql-test/r/flush.result:
Added test coverage for bug #57006 "Deadlock between HANDLER
and FLUSH TABLES WITH READ LOCK".
mysql-test/r/flush_read_lock.result:
Added test coverage for various aspects of FLUSH TABLES WITH
READ LOCK functionality.
mysql-test/r/flush_read_lock_kill.result:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Use new
debug_sync point. Do not disable concurrent inserts as now
InnoDB we always use InnoDB table.
mysql-test/r/handler_innodb.result:
Adjusted test case to the fact that now DROP TABLE closes
open HANDLERs for the table to be dropped before checking
if there active FTWRL in this connection.
mysql-test/r/handler_myisam.result:
Adjusted test case to the fact that now DROP TABLE closes
open HANDLERs for the table to be dropped before checking
if there active FTWRL in this connection.
mysql-test/r/mdl_sync.result:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Replaced
usage of GRL-specific debug_sync's with appropriate sync
points in MDL subsystem.
mysql-test/suite/perfschema/r/dml_setup_instruments.result:
Updated test results after removing global
COND_global_read_lock condition variable.
mysql-test/suite/perfschema/r/func_file_io.result:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/r/func_mutex.result:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/r/global_read_lock.result:
Adjusted test case to take into account that new GRL
implementation is based on MDL.
mysql-test/suite/perfschema/r/server_init.result:
Adjusted test case after replacing custom global read
lock implementation with one based on MDL and replacing
LOCK_event_metadata mutex with metadata lock.
mysql-test/suite/perfschema/t/func_file_io.test:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/t/func_mutex.test:
Ensure that this test doesn't affect subsequent tests.
At the end of its execution enable back P_S instrumentation
which this test disables at some point.
mysql-test/suite/perfschema/t/global_read_lock.test:
Adjusted test case to take into account that new GRL
implementation is based on MDL.
mysql-test/suite/perfschema/t/server_init.test:
Adjusted test case after replacing custom global read
lock implementation with one based on MDL and replacing
LOCK_event_metadata mutex with metadata lock.
mysql-test/suite/rpl/r/rpl_tmp_table_and_DDL.result:
Updated test results after prohibiting event DDL under
LOCK TABLES.
mysql-test/t/delayed.test:
Added test coverage for scenario which triggered assert in
metadata locking subsystem.
mysql-test/t/events_2.test:
Updated test case after prohibiting event DDL operations
under LOCK TABLES.
mysql-test/t/flush.test:
Added test coverage for bug #57006 "Deadlock between HANDLER
and FLUSH TABLES WITH READ LOCK".
mysql-test/t/flush_block_commit.test:
Adjusted test case after changing thread state name which
is used when COMMIT waits for FLUSH TABLES WITH READ LOCK
from "Waiting for release of readlock" to "Waiting for commit
lock".
mysql-test/t/flush_block_commit_notembedded.test:
Adjusted test case after changing thread state name which is
used when DML waits for FLUSH TABLES WITH READ LOCK. Now we
use "Waiting for global read lock" in this case.
mysql-test/t/flush_read_lock.test:
Added test coverage for various aspects of FLUSH TABLES WITH
READ LOCK functionality.
mysql-test/t/flush_read_lock_kill-master.opt:
We no longer need to use make_global_read_lock_block_commit_loop
debug tag in this test. Instead we rely on an appropriate
debug_sync point in MDL code.
mysql-test/t/flush_read_lock_kill.test:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Use new
debug_sync point. Do not disable concurrent inserts as now
InnoDB we always use InnoDB table.
mysql-test/t/lock_multi.test:
Adjusted test case after changing thread state names which
are used when DML or DDL waits for FLUSH TABLES WITH READ
LOCK to "Waiting for global read lock".
mysql-test/t/mdl_sync.test:
Adjusted test case after replacing custom global read lock
implementation with one based on metadata locks. Replaced
usage of GRL-specific debug_sync's with appropriate sync
points in MDL subsystem. Updated thread state names which
are used when DDL waits for FTWRL.
mysql-test/t/trigger_notembedded.test:
Adjusted test case after changing thread state names which
are used when DML or DDL waits for FLUSH TABLES WITH READ
LOCK to "Waiting for global read lock".
sql/event_data_objects.cc:
Removed Event_queue_element::status/last_executed_changed
members and Event_queue_element::update_timing_fields()
method. We no longer use this class for updating mysql.events
once event is chosen for execution. Accesses to instances of
this class in scheduler thread require protection by
Event_queue::LOCK_event_queue mutex and we try to avoid
updating table while holding this lock.
sql/event_data_objects.h:
Removed Event_queue_element::status/last_executed_changed
members and Event_queue_element::update_timing_fields()
method. We no longer use this class for updating mysql.events
once event is chosen for execution. Accesses to instances of
this class in scheduler thread require protection by
Event_queue::LOCK_event_queue mutex and we try to avoid
updating table while holding this lock.
sql/event_db_repository.cc:
- Changed Event_db_repository methods to not release all
metadata locks once they are done updating mysql.events
table. This allows to keep metadata lock protecting
against GRL and lock protecting particular event around
until corresponding DDL statement is written to the binary
log.
- Removed logic for conditional update of "status" and
"last_executed" fields from update_timing_fields_for_event()
method. In the only case when this method is called now
"last_executed" is always modified and tracking change
of "status" is too much hassle.
sql/event_db_repository.h:
Removed logic for conditional update of "status" and
"last_executed" fields from Event_db_repository::
update_timing_fields_for_event() method.
In the only case when this method is called now "last_executed"
is always modified and tracking change of "status" field is
too much hassle.
sql/event_queue.cc:
Changed event scheduler code not to update mysql.events
table while holding Event_queue::LOCK_event_queue mutex.
Doing so led to a deadlock with a new GRL implementation.
This deadlock didn't occur with old implementation due to
fact that code acquiring protection against GRL ignored
pending GRL requests (which lead to GRL starvation).
One of goals of new implementation is to disallow GRL
starvation and so we have to solve problem with this
deadlock in a different way.
sql/events.cc:
Changed methods of Events class to acquire protection
against GRL while perfoming DDL statement and keep it
until statement is written to the binary log.
Unfortunately this step together with new GRL implementation
exposed deadlock involving Events::LOCK_event_metadata
and GRL. To solve it Events::LOCK_event_metadata mutex was
replaced with a metadata lock on event. As a side-effect
events DDL has to be prohibited under LOCK TABLES even in
cases when mysql.events table was explicitly locked for
write.
sql/events.h:
Replaced Events::LOCK_event_metadata mutex with a metadata
lock on event.
sql/ha_ndbcluster.cc:
Updated code after replacing custom global read lock
implementation with one based on MDL. Since MDL subsystem
should now be able to detect deadlocks involving metadata
locks and GRL there is no need for special handling of
active GRL.
sql/handler.cc:
Replaced custom implementation of global read lock with
one based on metadata locks. Consequently when doing
commit instead of calling method of Global_read_lock
class to acquire protection against GRL we simply acquire
IX in COMMIT namespace.
sql/lock.cc:
Replaced custom implementation of global read lock with
one based on metadata locks. This step allows to expose
wait for GRL to deadlock detector of MDL subsystem and
thus succesfully resolve deadlocks similar to one behind
bug #57006 "Deadlock between HANDLER and FLUSH TABLES
WITH READ LOCK". It also solves problem with GRL starvation
described in bug #54673 "It takes too long to get readlock
for 'FLUSH TABLES WITH READ LOCK'" since metadata locks used
by GRL give preference to FTWRL statement instead of DML
statements (if needed in future this can be changed to
fair scheduling).
Similar to old implementation of acquisition of GRL is
two-step. During the first step we block all concurrent
DML and DDL statements by acquiring global S metadata lock
(each DML and DDL statement acquires global IX lock for
its duration). During the second step we block commits by
acquiring global S lock in COMMIT namespace (commit code
acquires global IX lock in this namespace).
Note that unlike in old implementation acquisition of
protection against GRL in DML and DDL is semi-automatic.
We assume that any statement which should be blocked by GRL
will either open and acquires write-lock on tables or acquires
metadata locks on objects it is going to modify. For any such
statement global IX metadata lock is automatically acquired
for its duration.
To support this change:
- Global_read_lock::lock/unlock_global_read_lock and
make_global_read_lock_block_commit methods were changed
accordingly.
- Global_read_lock::wait_if_global_read_lock() and
start_waiting_global_read_lock() methods were dropped.
It is now responsibility of code acquiring metadata locks
opening tables to acquire protection against GRL by
explicitly taking global IX lock with statement duration.
- Global variables, mutex and condition variable used by
old implementation was removed.
- lock_routine_name() was changed to use statement duration for
its global IX lock. It was also renamed to lock_object_name()
as it now also used to take metadata locks on events.
- Global_read_lock::set_explicit_lock_duration() was added which
allows not to release locks used for GRL when leaving prelocked
mode.
sql/lock.h:
- Renamed lock_routine_name() to lock_object_name() and changed
its signature to allow its usage for events.
- Removed broadcast_refresh() function. It is no longer needed
with new GRL implementation.
sql/log_event.cc:
Release metadata locks with statement duration at the end
of processing legacy event for LOAD DATA. This ensures that
replication thread processing such event properly releases
its protection against global read lock.
sql/mdl.cc:
Changed MDL subsystem to support new MDL-based implementation
of global read lock.
Added COMMIT and EVENTS namespaces for metadata locks. Changed
thread state name for GLOBAL namespace to "Waiting for global
read lock".
Optimized MDL_map::find_or_insert() method to avoid taking
m_mutex mutex when looking up MDL_lock objects for GLOBAL
or COMMIT namespaces. We keep pre-created MDL_lock objects
for these namespaces around and simply return pointers to
these global objects when needed.
Changed MDL_lock/MDL_scoped_lock to properly handle
notification of insert delayed handler threads when FTWRL
takes global S lock.
Introduced concept of lock duration. In addition to locks with
transaction duration which work in the way which is similar to
how locks worked before (i.e. they are released at the end of
transaction), locks with statement and explicit duration were
introduced.
Locks with statement duration are automatically released at the
end of statement. Locks with explicit duration require explicit
release and obsolete concept of transactional sentinel.
* Changed MDL_request and MDL_ticket classes to support notion
of duration.
* Changed MDL_context to keep locks with different duration in
different lists. Changed code handling ticket list to take
this into account.
* Changed methods responsible for releasing locks to take into
account duration of tickets. Particularly public
MDL_context::release_lock() method now only can release
tickets with explicit duration (there is still internal
method which allows to specify duration). To release locks
with statement or transaction duration one have to use
release_statement/transactional_locks() methods.
* Concept of savepoint for MDL subsystem now has to take into
account locks with statement duration. Consequently
MDL_savepoint class was introduced and methods working with
savepoints were updated accordingly.
* Added methods which allow to set duration for one or all
locks in the context.
sql/mdl.h:
Changed MDL subsystem to support new MDL-based implementation
of global read lock.
Added COMMIT and EVENTS namespaces for metadata locks.
Introduced concept of lock duration. In addition to locks with
transaction duration which work in the way which is similar to
how locks worked before (i.e. they are released at the end of
transaction), locks with statement and explicit duration were
introduced.
Locks with statement duration are automatically released at the
end of statement. Locks with explicit duration require explicit
release and obsolete concept of transactional sentinel.
* Changed MDL_request and MDL_ticket classes to support notion
of duration.
* Changed MDL_context to keep locks with different duration in
different lists. Changed code handling ticket list to take
this into account.
* Changed methods responsible for releasing locks to take into
account duration of tickets. Particularly public
MDL_context::release_lock() method now only can release
tickets with explicit duration (there is still internal
method which allows to specify duration). To release locks
with statement or transaction duration one have to use
release_statement/transactional_locks() methods.
* Concept of savepoint for MDL subsystem now has to take into
account locks with statement duration. Consequently
MDL_savepoint class was introduced and methods working with
savepoints were updated accordingly.
* Added methods which allow to set duration for one or all
locks in the context.
sql/mysqld.cc:
Removed global mutex and condition variables which were used
by old implementation of GRL.
Also we no longer need to initialize Events::LOCK_event_metadata
mutex as it was replaced with metadata locks on events.
sql/mysqld.h:
Removed global variable, mutex and condition variables which
were used by old implementation of GRL.
sql/rpl_rli.cc:
When slave thread closes tables which were open for handling
of RBR events ensure that it releases global IX lock which
was acquired as protection against GRL.
sql/sp.cc:
Adjusted code to the new signature of lock_object/routine_name(),
to the fact that one now needs specify duration of lock when
initializing MDL_request and to the fact that savepoints for MDL
subsystem are now represented by MDL_savepoint class.
sql/sp_head.cc:
Ensure that statements in stored procedures release statement
metadata locks and thus release their protectiong against GRL
in proper moment in time.
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/sql_admin.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/sql_base.cc:
- Implemented support for new approach to acquiring protection
against global read lock. We no longer acquire such protection
explicitly on the basis of statement flags. Instead we always
rely on code which is responsible for acquiring metadata locks
on object to be changed acquiring this protection. This is
achieved by acquiring global IX metadata lock with statement
duration. Code doing this also responsible for checking that
current connection has no active GRL by calling an
Global_read_lock::can_acquire_protection() method.
Changed code in open_table() and lock_table_names()
accordingly.
Note that as result of this change DDL and DML on temporary
tables is always compatible with GRL (before it was
incompatible in some cases and compatible in other cases).
- To speed-up code acquiring protection against GRL introduced
m_has_protection_against_grl member in Open_table_context
class. It indicates that protection was already acquired
sometime during open_tables() execution and new attempts
can be skipped.
- Thanks to new GRL implementation calls to broadcast_refresh()
became unnecessary and were removed.
- Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request and to the fact that
savepoints for MDL subsystem are now represented by
MDL_savepoint class.
sql/sql_base.h:
Adjusted code to the fact that savepoints for MDL subsystem are
now represented by MDL_savepoint class.
Also introduced Open_table_context::m_has_protection_against_grl
member which allows to avoid acquiring protection against GRL
while opening tables if such protection was already acquired.
sql/sql_class.cc:
Changed THD::leave_locked_tables_mode() after transactional
sentinel for metadata locks was obsoleted by introduction of
locks with explicit duration.
sql/sql_class.h:
- Adjusted code to the fact that savepoints for MDL subsystem
are now represented by MDL_savepoint class.
- Changed Global_read_lock class according to changes in
global read lock implementation:
* wait_if_global_read_lock and start_waiting_global_read_lock
are now gone. Instead code needing protection against GRL
has to acquire global IX metadata lock with statement
duration itself. To help it new can_acquire_protection()
was introduced. Also as result of the above change
m_protection_count member is gone too.
* Added m_mdl_blocks_commits_lock member to store metadata
lock blocking commits.
* Adjusted code to the fact that concept of transactional
sentinel was obsoleted by concept of lock duration.
- Removed CF_PROTECT_AGAINST_GRL flag as it is no longer
necessary. New GRL implementation acquires protection
against global read lock automagically when statement
acquires metadata locks on tables or other objects it
is going to change.
sql/sql_db.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/sql_handler.cc:
Removed call to broadcast_refresh() function. It is no longer
needed with new GRL implementation.
Adjusted code after introducing duration concept for metadata
locks. Particularly to the fact transactional sentinel was
replaced with explicit duration.
sql/sql_handler.h:
Renamed mysql_ha_move_tickets_after_trans_sentinel() to
mysql_ha_set_explicit_lock_duration() after transactional
sentinel was obsoleted by locks with explicit duration.
sql/sql_insert.cc:
Adjusted code handling delaying inserts after switching to
new GRL implementation. Now connection thread initiating
delayed insert has to acquire global IX lock in addition
to metadata lock on table being inserted into. This IX lock
protects against GRL and similarly to SW lock on table being
inserted into has to be passed to handler thread in order to
avoid deadlocks.
sql/sql_lex.cc:
LEX::protect_against_global_read_lock member is no longer
necessary since protection against GRL is automatically
taken by code acquiring metadata locks/opening tables.
sql/sql_lex.h:
LEX::protect_against_global_read_lock member is no longer
necessary since protection against GRL is automatically
taken by code acquiring metadata locks/opening tables.
sql/sql_parse.cc:
- Implemented support for new approach to acquiring protection
against global read lock. We no longer acquire such protection
explicitly on the basis of statement flags. Instead we always
rely on code which is responsible for acquiring metadata locks
on object to be changed acquiring this protection. This is
achieved by acquiring global IX metadata lock with statement
duration. This lock is automatically released at the end of
statement execution.
- Changed implementation of CREATE/DROP PROCEDURE/FUNCTION not
to release metadata locks and thus protection against of GRL
in the middle of statement execution.
- Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request and to the fact that
savepoints for MDL subsystem are now represented by
MDL_savepoint class.
sql/sql_prepare.cc:
Adjusted code to the to the fact that savepoints for MDL
subsystem are now represented by MDL_savepoint class.
sql/sql_rename.cc:
With new GRL implementation there is no need to explicitly
acquire protection against GRL before renaming tables.
This happens automatically in code which acquires metadata
locks on tables being renamed.
sql/sql_show.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request and to the fact that
savepoints for MDL subsystem are now represented by
MDL_savepoint class.
sql/sql_table.cc:
- With new GRL implementation there is no need to explicitly
acquire protection against GRL before dropping tables.
This happens automatically in code which acquires metadata
locks on tables being dropped.
- Changed mysql_alter_table() not to release lock on new table
name explicitly and to rely on automatic release of locks
at the end of statement instead. This was necessary since
now MDL_context::release_lock() is supported only for locks
for explicit duration.
sql/sql_trigger.cc:
With new GRL implementation there is no need to explicitly
acquire protection against GRL before changing table triggers.
This happens automatically in code which acquires metadata
locks on tables which triggers are to be changed.
sql/sql_update.cc:
Fix bug exposed by GRL testing. During prepare phase acquire
only S metadata locks instead of SW locks to keep prepare of
multi-UPDATE compatible with concurrent LOCK TABLES WRITE
and global read lock.
sql/sql_view.cc:
With new GRL implementation there is no need to explicitly
acquire protection against GRL before creating view.
This happens automatically in code which acquires metadata
lock on view to be created.
sql/sql_yacc.yy:
LEX::protect_against_global_read_lock member is no longer
necessary since protection against GRL is automatically
taken by code acquiring metadata locks/opening tables.
sql/table.cc:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/table.h:
Adjusted code to the fact that one now needs specify duration
of lock when initializing MDL_request.
sql/transaction.cc:
Replaced custom implementation of global read lock with
one based on metadata locks. Consequently when doing
commit instead of calling method of Global_read_lock
class to acquire protection against GRL we simply acquire
IX in COMMIT namespace.
Also adjusted code to the fact that MDL savepoint is now
represented by MDL_savepoint class.
After the WL#2687, the binlog_cache_size and max_binlog_cache_size affect both the
stmt-cache and the trx-cache. This means that the resource used is twice the amount
expected/defined by the user.
The binlog_cache_use is incremented when the stmt-cache or the trx-cache is used
and binlog_cache_disk_use is incremented when the disk space from the stmt-cache or the
trx-cache is used. This behavior does not allow to distinguish which cache may be harming
performance due to the extra disk accesses and needs to have its in-memory cache
increased.
To fix the problem, we introduced two new options and status variables related to the
stmt-cache:
Options:
. binlog_stmt_cache_size
. max_binlog_stmt_cache_size
Status Variables:
. binlog_stmt_cache_use
. binlog_stmt_cache_disk_use
So there are
. binlog_cache_size that defines the size of the transactional cache for
updates to transactional engines for the binary log.
. binlog_stmt_cache_size that defines the size of the statement cache for
updates to non-transactional engines for the binary log.
. max_binlog_cache_size that sets the total size of the transactional
cache.
. max_binlog_stmt_cache_size that sets the total size of the statement
cache.
. binlog_cache_use that identifies the number of transactions that used the
temporary transactional binary log cache.
. binlog_cache_disk_use that identifies the number of transactions that used
the temporary transactional binary log cache but that exceeded the value of
binlog_cache_size.
. binlog_stmt_cache_use that identifies the number of statements that used the
temporary non-transactional binary log cache.
. binlog_stmt_cache_disk_use that identifies the number of statements that used
the temporary non-transactional binary log cache but that exceeded the value of
binlog_stmt_cache_size.
include/my_sys.h:
Updated message on disk_writes' usage.
mysql-test/extra/binlog_tests/binlog_cache_stat.test:
Updated the test case and added code to check the new status variables
binlog_stmt_cache_use and binlog_stmt_cache_disk_use.
mysql-test/extra/rpl_tests/rpl_binlog_max_cache_size.test:
Updated the test case to use the new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size.
mysql-test/r/mysqld--help-notwin.result:
Updated the result file.
mysql-test/suite/binlog/r/binlog_mixed_cache_stat.result:
Updated the result file.
mysql-test/suite/binlog/r/binlog_row_cache_stat.result:
Updated the result file.
mysql-test/suite/binlog/r/binlog_stm_cache_stat.result:
Updated the result file.
mysql-test/suite/rpl/r/rpl_mixed_binlog_max_cache_size.result:
Update the result file.
mysql-test/suite/rpl/r/rpl_row_binlog_max_cache_size.result:
Update the result file.
mysql-test/suite/rpl/r/rpl_stm_binlog_max_cache_size.result:
Updated the result file.
mysql-test/suite/sys_vars/inc/binlog_stmt_cache_size_basic.inc:
Added a test case to check the binlog_stmt_cache_size.
mysql-test/suite/sys_vars/r/binlog_stmt_cache_size_basic_32.result:
Updated the result file.
mysql-test/suite/sys_vars/r/binlog_stmt_cache_size_basic_64.result:
Updated the result file.
mysql-test/suite/sys_vars/r/max_binlog_stmt_cache_size_basic.result:
Updated the result file.
mysql-test/suite/sys_vars/t/binlog_stmt_cache_size_basic_32.test:
Added a test case to check the binlog_stmt_cache_size.
mysql-test/suite/sys_vars/t/binlog_stmt_cache_size_basic_64.test:
Added a test case to check the binlog_stmt_cache_size.
mysql-test/suite/sys_vars/t/max_binlog_cache_size_func-master.opt:
Removed because there is no test case max_binlog_cache_size_func.
mysql-test/suite/sys_vars/t/max_binlog_stmt_cache_size_basic.test:
Added a test case to check the system variable max_binlog_stmt_cache_size.
sql/log.cc:
There two main changes in here:
. Changed the set_write_error() as an error message is set according
to the type of the cache.
. Created the function set_binlog_cache_info where references to the
appropriate status and system variables are set and the server can
smoothly compute statistics and set the maximum size for each cache.
sql/log.h:
Changed the signature of the function in order to identify the error message
to be printed out as there is a different error code for each type of cache.
sql/mysqld.cc:
Added new status variables binlog_stmt_cache_use and binlog_stmt_cache_disk_use.
sql/mysqld.h:
Added new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size.
sql/share/errmsg-utf8.txt:
Added new error message related to the statement cache.
sql/sys_vars.cc:
Added new system variables max_binlog_stmt_cache_size and binlog_stmt_cache_size.
add boolean command-line option --autocommit.
mysql-test/mysql-test-run.pl:
do in --gdb like in --ddd: to let the developer debug the startup
phase (like command-line options parsing), don't "run".
It's the third time I do this change, it was previously lost
by merges, port of 6.0 to next-mr...
mysql-test/r/mysqld--help-notwin.result:
new command-line option
mysql-test/r/mysqld--help-win.result:
a Linux user's best guess at what the Windows result should be
mysql-test/suite/sys_vars/inc/autocommit_func2.inc:
new test
mysql-test/suite/sys_vars/t/autocommit_func2-master.opt:
test new option
mysql-test/suite/sys_vars/t/autocommit_func3-master.opt:
test new option
sql/mysqld.cc:
new --autocommit
sql/mysqld.h:
new --autocommit
sql/sql_partition.cc:
What matters to this partitioning quote is to have
the OPTION_QUOTE_SHOW_CREATE flag down, it's all
that append_identifier() uses. So we make it explicit.
TABLES <list> WITH READ LOCK are incompatible".
The problem was that FLUSH TABLES <list> WITH READ LOCK
which was issued when other connection has acquired global
read lock using FLUSH TABLES WITH READ LOCK was blocked
and has to wait until global read lock is released.
This issue stemmed from the fact that FLUSH TABLES <list>
WITH READ LOCK implementation has acquired X metadata locks
on tables to be flushed. Since these locks required acquiring
of global IX lock this statement was incompatible with global
read lock.
This patch addresses problem by using SNW metadata type of
lock for tables to be flushed by FLUSH TABLES <list> WITH
READ LOCK. It is OK to acquire them without global IX lock
as long as we won't try to upgrade those locks. Since SNW
locks allow concurrent statements using same table FLUSH
TABLE <list> WITH READ LOCK now has to wait until old
versions of tables to be flushed go away after acquiring
metadata locks. Since such waiting can lead to deadlock
MDL deadlock detector was extended to take into account
waits for flush and resolve such deadlocks.
As a bonus code in open_tables() which was responsible for
waiting old versions of tables to go away was refactored.
Now when we encounter old version of table in open_table()
we don't back-off and wait for all old version to go away,
but instead wait for this particular table to be flushed.
Such approach supported by deadlock detection should reduce
number of scenarios in which FLUSH TABLES aborts concurrent
multi-statement transactions.
Note that active FLUSH TABLES <list> WITH READ LOCK still
blocks concurrent FLUSH TABLES WITH READ LOCK statement
as the former keeps tables open and thus prevents the
latter statement from doing flush.
mysql-test/include/handler.inc:
Adjusted test case after changing status which is set
when FLUSH TABLES waits for tables to be flushed from
"Flushing tables" to "Waiting for table".
mysql-test/r/flush.result:
Added test which checks that "flush tables <list> with
read lock" is compatible with active "flush tables with
read lock" but not vice-versa. This test also covers
bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES
<list> WITH READ LOCK are incompatible".
mysql-test/r/mdl_sync.result:
Added scenarios in which wait for table to be flushed
causes deadlocks to the coverage of MDL deadlock detector.
mysql-test/suite/perfschema/r/dml_setup_instruments.result:
Adjusted test results after removal of COND_refresh
condition variable.
mysql-test/suite/perfschema/r/server_init.result:
Adjusted test and its results after removal of COND_refresh
condition variable.
mysql-test/suite/perfschema/t/server_init.test:
Adjusted test and its results after removal of COND_refresh
condition variable.
mysql-test/t/flush.test:
Added test which checks that "flush tables <list> with
read lock" is compatible with active "flush tables with
read lock" but not vice-versa. This test also covers
bug #52044 "FLUSH TABLES WITH READ LOCK and FLUSH TABLES
<list> WITH READ LOCK are incompatible".
mysql-test/t/kill.test:
Adjusted test case after changing status which is set
when FLUSH TABLES waits for tables to be flushed from
"Flushing tables" to "Waiting for table".
mysql-test/t/lock_multi.test:
Adjusted test case after changing status which is set
when FLUSH TABLES waits for tables to be flushed from
"Flushing tables" to "Waiting for table".
mysql-test/t/mdl_sync.test:
Added scenarios in which wait for table to be flushed
causes deadlocks to the coverage of MDL deadlock detector.
sql/ha_ndbcluster.cc:
Adjusted code after adding one more parameter for
close_cached_tables() call - timeout for waiting for
table to be flushed.
sql/ha_ndbcluster_binlog.cc:
Adjusted code after adding one more parameter for
close_cached_tables() call - timeout for waiting for
table to be flushed.
sql/lock.cc:
Removed COND_refresh condition variable. See comment
for sql_base.cc for details.
sql/mdl.cc:
Now MDL deadlock detector takes into account information
about waits for table flushes when searching for deadlock.
To implement this change:
- Declaration of enum_deadlock_weight and
Deadlock_detection_visitor were moved to mdl.h header
to make them available to the code in table.cc which
implements deadlock detector traversal through edges
of waiters graph representing waiting for flush.
- Since now MDL_context may wait not only for metadata
lock but also for table to be flushed an abstract
Wait_for_edge class was introduced. Its descendants
MDL_ticket and Flush_ticket incapsulate specifics
of inspecting waiters graph when following through
edge representing wait of particular type.
We no longer require global IX metadata lock when acquiring
SNW or SNRW locks. Such locks are needed only when metadata
locks of these types are upgraded to X locks. This allows
to use SNW locks in FLUSH TABLES <list> WITH READ LOCK
implementation and keep the latter compatible with global
read lock.
sql/mdl.h:
Now MDL deadlock detector takes into account information
about waits for table flushes when searching for deadlock.
To implement this change:
- Declaration of enum_deadlock_weight and
Deadlock_detection_visitor were moved to mdl.h header
to make them available to the code in table.cc which
implements deadlock detector traversal through edges
of waiters graph representing waiting for flush.
- Since now MDL_context may wait not only for metadata
lock but also for table to be flushed an abstract
Wait_for_edge class was introduced. Its descendants
MDL_ticket and Flush_ticket incapsulate specifics
of inspecting waiters graph when following through
edge representing wait of particular type.
- Deadlock_detection_visitor now has m_table_shares_visited
member which allows to support recursive locking for
LOCK_open. This is required when deadlock detector
inspects waiters graph which contains several edges
representing waits for flushes or needs to come through
the such edge more than once.
sql/mysqld.cc:
Removed COND_refresh condition variable. See comment
for sql_base.cc for details.
sql/mysqld.h:
Removed COND_refresh condition variable. See comment
for sql_base.cc for details.
sql/sql_base.cc:
Changed approach to how threads are waiting for table
to be flushed. Now thread that wants to wait for old
table to go away subscribes for notification by adding
Flush_ticket to table's share and waits using
MDL_context::m_wait object. Once table gets flushed
(i.e. all tables are closed and table share is ready
to be destroyed) all such waiters are notified
individually.
Thanks to this change MDL deadlock detector can take
such waits into account.
To implement this/as result of this change:
- tdc_wait_for_old_versions() was replaced with
tdc_wait_for_old_version() which waits for individual
old share to go away and which is called by open_table()
after finding out that share is outdated. We don't
need to perform back-off before such waiting thanks
to the fact that deadlock detector now sees such waits.
- As result Open_table_ctx::m_mdl_requests became
unnecessary and was removed. We no longer allocate
copies of MDL_request objects on MEM_ROOT when
MYSQL_OPEN_FORCE_SHARED/SHARED_HIGH_PRIO flags are
in effect.
- close_cached_tables() and tdc_wait_for_old_version()
share code which implements waiting for share to be
flushed - the both use TABLE_SHARE::wait_until_flush()
method. Thanks to this close_cached_tables() supports
timeouts and has extra parameter for this.
- Open_table_context::OT_MDL_CONFLICT enum element was
renamed to OT_CONFLICT as it is now also used in cases
when back-off is required to resolve deadlock caused
by waiting for flush and not metadata lock.
- In cases when we discover that current connection tries
to open tables from different generation we now simply
back-off and restart process of opening tables. To
support this Open_table_context::OT_REOPEN_TABLES enum
element was added.
- COND_refresh condition variable became unnecessary and
was removed.
- mysql_notify_thread_having_shared_lock() no longer wakes
up connections waiting for flush as all such connections
can be waken up by deadlock detector if necessary.
sql/sql_base.h:
- close_cached_tables() now has one more parameter -
timeout for waiting for table to be flushed.
- Open_table_context::OT_MDL_CONFLICT enum element was
renamed to OT_CONFLICT as it is now also used in cases
when back-off is required to resolve deadlock caused
by waiting for flush and not metadata lock.
Added new OT_REOPEN_TABLES enum element to be used in
cases when we need to restart open tables process even
in the middle of transaction.
- Open_table_ctx::m_mdl_requests became unnecessary and
was removed.
sql/sql_class.h:
Added assert ensuring that we won't use LOCK_open mutex
with THD::enter_cond(). Otherwise deadlocks can arise in
MDL deadlock detector.
sql/sql_parse.cc:
Changed FLUSH TABLES <list> WITH READ LOCK to take SNW
metadata locks instead of X locks on tables to be flushed.
Since we no longer require global IX lock to be taken
when SNW locks are taken this makes this statement
compatible with FLUSH TABLES WITH READ LOCK statement.
Since SNW locks allow other connections to have table
opened FLUSH TABLES <list> WITH READ LOCK now has to
wait during open_tables() for old version to go away.
Such waits can lead to deadlocks which will be detected
by MDL deadlock detector which now takes waits for table
to be flushed into account.
Also adjusted code after adding one more parameter for
close_cached_tables() call - timeout for waiting for
table to be flushed.
sql/sql_yacc.yy:
FLUSH TABLES <list> WITH READ LOCK now needs only SNW
metadata locks on tables.
sql/sys_vars.cc:
Adjusted code after adding one more parameter for
close_cached_tables() call - timeout for waiting for
table to be flushed.
sql/table.cc:
Implemented new approach to how threads are waiting for
table to be flushed. Now thread that wants to wait for
old table to go away subscribes for notification by
adding Flush_ticket to table's share and waits using
MDL_context::m_wait object. Once table gets flushed
(i.e. all tables are closed and table share is ready
to be destroyed) all such waiters are notified
individually. This change allows to make such waits
visible inside of MDL deadlock detector.
To do it:
- Added list of waiters/Flush_tickets to TABLE_SHARE
class.
- Changed free_table_share() to postpone freeing of
share memory until last waiter goes away and to
wake up subscribed waiters.
- Added TABLE_SHARE::wait_until_flushed() method which
implements subscription to the list of waiters for
table to be flushed and waiting for this event.
Implemented interface which allows to expose waits for
flushes to MDL deadlock detector:
- Introduced Flush_ticket class a descendant of
Wait_for_edge class.
- Added TABLE_SHARE::find_deadlock() method which allows
deadlock detector to find out what contexts are still
using old version of table in question (i.e. to find
out what contexts are waited for by owner of
Flush_ticket).
sql/table.h:
In order to support new strategy of waiting for table flush
(see comment for table.cc for details) added list of
waiters/Flush_tickets to TABLE_SHARE class.
Implemented interface which allows to expose waits for
flushes to MDL deadlock detector:
- Introduced Flush_ticket class a descendant of
Wait_for_edge class.
- Added TABLE_SHARE::find_deadlock() method which allows
deadlock detector to find out what contexts are still
using old version of table in question (i.e. to find
out what contexts are waited for by owner of
Flush_ticket).
DATABASE with open HANDLER"
Remove LOCK_create_db, database name locks, and use metadata locks instead.
This exposes CREATE/DROP/ALTER DATABASE statements to the graph-based
deadlock detector in MDL, and paves the way for a safe, deadlock-free
implementation of RENAME DATABASE.
Database DDL statements will now take exclusive metadata locks on
the database name, while table/view/routine DDL statements take
intention exclusive locks on the database name. This prevents race
conditions between database DDL and table/view/routine DDL.
(e.g. DROP DATABASE with concurrent CREATE/ALTER/DROP TABLE)
By adding database name locks, this patch implements
WL#4450 "DDL locking: CREATE/DROP DATABASE must use database locks" and
WL#4985 "DDL locking: namespace/hierarchical locks".
The patch also changes code to use init_one_table() where appropriate.
The new lock_table_names() function requires TABLE_LIST::db_length to
be set correctly, and this is taken care of by init_one_table().
This patch also adds a simple template to help work with
the mysys HASH data structure.
Most of the patch was written by Konstantin Osipov.
In order to allow thread schedulers to be dynamically loaded,
it is necessary to make the following changes to the server:
- Two new service interfaces
- Modifications to InnoDB to inform the thread scheduler of state changes.
- Changes to the VIO subsystem for checking if data is available on a socket.
- Elimination of remains of the old thread pool implementation.
The two new service interfaces introduces are:
my_thread_scheduler
A service interface to register a thread
scheduler.
thd_wait
A service interface to inform thread scheduler
that the thread is about to start waiting.
In addition, the patch adds code that:
- Add a call to thd_wait for table locks in mysys
thd_lock.c by introducing a set function that
can be used to set a callback to be used when
waiting on a lock and resuming from waiting.
- Calling the mysys set function from the server
to set the callbacks correctly.
Conflicts:
Text conflict in mysql-test/r/explain.result
Text conflict in mysql-test/t/explain.test
Text conflict in sql/net_serv.cc
Text conflict in sql/sp_head.cc
Text conflict in sql/sql_priv.h
when trying to build innodb as plugin.
The reason for the error is mismatch in mysql_temp_dir_list
declaration between mysqld.h and usage in ha_innodb.cc
Add missing MYSQL_PLUGIN_IMPORT to mysql_tmpdir_list
(variables exported by the server and used by plugin need it).
This patch:
- Moves all definitions from the mysql_priv.h file into
header files for the component where the variable is
defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h
