The reason for the failure was a bug in an include file on debian that causes 'struct stat'
to have different sized depending on the environment.
This patch fixes so that we always include my_global.h or my_config.h before we include any other files.
Other things:
- Removed #include <my_global.h> in some include files; Better to always do this at the top level to have as few
"always-include-this-file-first' files as possible.
- Removed usage of some include files that where already included by my_global.h or by other files.
client/mysql_plugin.c:
Use my_global.h first
client/mysqlslap.c:
Remove duplicated include files
extra/comp_err.c:
Remove duplicated include files
include/m_string.h:
Remove duplicated include files
include/maria.h:
Remove duplicated include files
libmysqld/emb_qcache.cc:
Use my_global.h first
plugin/semisync/semisync.h:
Use my_pthread.h first
sql/datadict.cc:
Use my_global.h first
sql/debug_sync.cc:
Use my_global.h first
sql/derror.cc:
Use my_global.h first
sql/des_key_file.cc:
Use my_global.h first
sql/discover.cc:
Use my_global.h first
sql/event_data_objects.cc:
Use my_global.h first
sql/event_db_repository.cc:
Use my_global.h first
sql/event_parse_data.cc:
Use my_global.h first
sql/event_queue.cc:
Use my_global.h first
sql/event_scheduler.cc:
Use my_global.h first
sql/events.cc:
Use my_global.h first
sql/field.cc:
Use my_global.h first
Remove duplicated include files
sql/field_conv.cc:
Use my_global.h first
sql/filesort.cc:
Use my_global.h first
Remove duplicated include files
sql/gstream.cc:
Use my_global.h first
sql/ha_ndbcluster.cc:
Use my_global.h first
sql/ha_ndbcluster_binlog.cc:
Use my_global.h first
sql/ha_ndbcluster_cond.cc:
Use my_global.h first
sql/ha_partition.cc:
Use my_global.h first
sql/handler.cc:
Use my_global.h first
sql/hash_filo.cc:
Use my_global.h first
sql/hostname.cc:
Use my_global.h first
sql/init.cc:
Use my_global.h first
sql/item.cc:
Use my_global.h first
sql/item_buff.cc:
Use my_global.h first
sql/item_cmpfunc.cc:
Use my_global.h first
sql/item_create.cc:
Use my_global.h first
sql/item_geofunc.cc:
Use my_global.h first
sql/item_inetfunc.cc:
Use my_global.h first
sql/item_row.cc:
Use my_global.h first
sql/item_strfunc.cc:
Use my_global.h first
sql/item_subselect.cc:
Use my_global.h first
sql/item_sum.cc:
Use my_global.h first
sql/item_timefunc.cc:
Use my_global.h first
sql/item_xmlfunc.cc:
Use my_global.h first
sql/key.cc:
Use my_global.h first
sql/lock.cc:
Use my_global.h first
sql/log.cc:
Use my_global.h first
sql/log_event.cc:
Use my_global.h first
sql/log_event_old.cc:
Use my_global.h first
sql/mf_iocache.cc:
Use my_global.h first
sql/mysql_install_db.cc:
Remove duplicated include files
sql/mysqld.cc:
Remove duplicated include files
sql/net_serv.cc:
Remove duplicated include files
sql/opt_range.cc:
Use my_global.h first
sql/opt_subselect.cc:
Use my_global.h first
sql/opt_sum.cc:
Use my_global.h first
sql/parse_file.cc:
Use my_global.h first
sql/partition_info.cc:
Use my_global.h first
sql/procedure.cc:
Use my_global.h first
sql/protocol.cc:
Use my_global.h first
sql/records.cc:
Use my_global.h first
sql/records.h:
Don't include my_global.h
Better to do this at the upper level
sql/repl_failsafe.cc:
Use my_global.h first
sql/rpl_filter.cc:
Use my_global.h first
sql/rpl_gtid.cc:
Use my_global.h first
sql/rpl_handler.cc:
Use my_global.h first
sql/rpl_injector.cc:
Use my_global.h first
sql/rpl_record.cc:
Use my_global.h first
sql/rpl_record_old.cc:
Use my_global.h first
sql/rpl_reporting.cc:
Use my_global.h first
sql/rpl_rli.cc:
Use my_global.h first
sql/rpl_tblmap.cc:
Use my_global.h first
sql/rpl_utility.cc:
Use my_global.h first
sql/set_var.cc:
Added comment
sql/slave.cc:
Use my_global.h first
sql/sp.cc:
Use my_global.h first
sql/sp_cache.cc:
Use my_global.h first
sql/sp_head.cc:
Use my_global.h first
sql/sp_pcontext.cc:
Use my_global.h first
sql/sp_rcontext.cc:
Use my_global.h first
sql/spatial.cc:
Use my_global.h first
sql/sql_acl.cc:
Use my_global.h first
sql/sql_admin.cc:
Use my_global.h first
sql/sql_analyse.cc:
Use my_global.h first
sql/sql_audit.cc:
Use my_global.h first
sql/sql_base.cc:
Use my_global.h first
sql/sql_binlog.cc:
Use my_global.h first
sql/sql_bootstrap.cc:
Use my_global.h first
Use my_global.h first
sql/sql_cache.cc:
Use my_global.h first
sql/sql_class.cc:
Use my_global.h first
sql/sql_client.cc:
Use my_global.h first
sql/sql_connect.cc:
Use my_global.h first
sql/sql_crypt.cc:
Use my_global.h first
sql/sql_cursor.cc:
Use my_global.h first
sql/sql_db.cc:
Use my_global.h first
sql/sql_delete.cc:
Use my_global.h first
sql/sql_derived.cc:
Use my_global.h first
sql/sql_do.cc:
Use my_global.h first
sql/sql_error.cc:
Use my_global.h first
sql/sql_explain.cc:
Use my_global.h first
sql/sql_expression_cache.cc:
Use my_global.h first
sql/sql_handler.cc:
Use my_global.h first
sql/sql_help.cc:
Use my_global.h first
sql/sql_insert.cc:
Use my_global.h first
sql/sql_lex.cc:
Use my_global.h first
sql/sql_load.cc:
Use my_global.h first
sql/sql_locale.cc:
Use my_global.h first
sql/sql_manager.cc:
Use my_global.h first
sql/sql_parse.cc:
Use my_global.h first
sql/sql_partition.cc:
Use my_global.h first
sql/sql_plugin.cc:
Added comment
sql/sql_prepare.cc:
Use my_global.h first
sql/sql_priv.h:
Added error if we use this before including my_global.h
This check is here becasue so many files includes sql_priv.h first.
sql/sql_profile.cc:
Use my_global.h first
sql/sql_reload.cc:
Use my_global.h first
sql/sql_rename.cc:
Use my_global.h first
sql/sql_repl.cc:
Use my_global.h first
sql/sql_select.cc:
Use my_global.h first
sql/sql_servers.cc:
Use my_global.h first
sql/sql_show.cc:
Added comment
sql/sql_signal.cc:
Use my_global.h first
sql/sql_statistics.cc:
Use my_global.h first
sql/sql_table.cc:
Use my_global.h first
sql/sql_tablespace.cc:
Use my_global.h first
sql/sql_test.cc:
Use my_global.h first
sql/sql_time.cc:
Use my_global.h first
sql/sql_trigger.cc:
Use my_global.h first
sql/sql_udf.cc:
Use my_global.h first
sql/sql_union.cc:
Use my_global.h first
sql/sql_update.cc:
Use my_global.h first
sql/sql_view.cc:
Use my_global.h first
sql/sys_vars.cc:
Added comment
sql/table.cc:
Use my_global.h first
sql/thr_malloc.cc:
Use my_global.h first
sql/transaction.cc:
Use my_global.h first
sql/uniques.cc:
Use my_global.h first
sql/unireg.cc:
Use my_global.h first
sql/unireg.h:
Removed inclusion of my_global.h
storage/archive/ha_archive.cc:
Added comment
storage/blackhole/ha_blackhole.cc:
Use my_global.h first
storage/csv/ha_tina.cc:
Use my_global.h first
storage/csv/transparent_file.cc:
Use my_global.h first
storage/federated/ha_federated.cc:
Use my_global.h first
storage/federatedx/federatedx_io.cc:
Use my_global.h first
storage/federatedx/federatedx_io_mysql.cc:
Use my_global.h first
storage/federatedx/federatedx_io_null.cc:
Use my_global.h first
storage/federatedx/federatedx_txn.cc:
Use my_global.h first
storage/heap/ha_heap.cc:
Use my_global.h first
storage/innobase/handler/handler0alter.cc:
Use my_global.h first
storage/maria/ha_maria.cc:
Use my_global.h first
storage/maria/unittest/ma_maria_log_cleanup.c:
Remove duplicated include files
storage/maria/unittest/test_file.c:
Added comment
storage/myisam/ha_myisam.cc:
Move sql_plugin.h first as this includes my_global.h
storage/myisammrg/ha_myisammrg.cc:
Use my_global.h first
storage/oqgraph/oqgraph_thunk.cc:
Use my_config.h and my_global.h first
One could not include my_global.h before oqgraph_thunk.h (don't know why)
storage/spider/ha_spider.cc:
Use my_global.h first
storage/spider/hs_client/config.cpp:
Use my_global.h first
storage/spider/hs_client/escape.cpp:
Use my_global.h first
storage/spider/hs_client/fatal.cpp:
Use my_global.h first
storage/spider/hs_client/hstcpcli.cpp:
Use my_global.h first
storage/spider/hs_client/socket.cpp:
Use my_global.h first
storage/spider/hs_client/string_util.cpp:
Use my_global.h first
storage/spider/spd_conn.cc:
Use my_global.h first
storage/spider/spd_copy_tables.cc:
Use my_global.h first
storage/spider/spd_db_conn.cc:
Use my_global.h first
storage/spider/spd_db_handlersocket.cc:
Use my_global.h first
storage/spider/spd_db_mysql.cc:
Use my_global.h first
storage/spider/spd_db_oracle.cc:
Use my_global.h first
storage/spider/spd_direct_sql.cc:
Use my_global.h first
storage/spider/spd_i_s.cc:
Use my_global.h first
storage/spider/spd_malloc.cc:
Use my_global.h first
storage/spider/spd_param.cc:
Use my_global.h first
storage/spider/spd_ping_table.cc:
Use my_global.h first
storage/spider/spd_sys_table.cc:
Use my_global.h first
storage/spider/spd_table.cc:
Use my_global.h first
storage/spider/spd_trx.cc:
Use my_global.h first
storage/xtradb/handler/handler0alter.cc:
Use my_global.h first
storage/xtradb/handler/i_s.cc:
Use my_global.h first
Moved freeing of mutex earlier, as we don't need to have log_space_cond locked for doing rotate_relay_log()
sql/slave.cc:
Moved freeing of mutex earlier, as we don't need to have log_space_cond locked for doing rotate_relay_log()
If the slave gets a reconnect in the middle of a GTID event group, normally
it will re-fetch that event group, skipping the first part that was already
queued for the SQL thread.
However, if the master crashed while writing the event group, the group is
incomplete. This patch detects this case and makes sure that the
transaction is rolled back and nothing is skipped from any following
event groups.
Similarly, a network proxy might cause the reconnect to end up on a
different master server. Detect this by noticing a different server_id,
and similarly in this case roll back the partially received group.
Merged lp:maria/maria-10.0-galera up to revision 3880.
Added a new functions to handler API to forcefully abort_transaction,
producing fake_trx_id, get_checkpoint and set_checkpoint for XA. These
were added for future possiblity to add more storage engines that
could use galera replication.
Merged lp:maria/maria-10.0-galera up to revision 3879.
Added a new functions to handler API to forcefully abort_transaction,
producing fake_trx_id, get_checkpoint and set_checkpoint for XA. These
were added for future possiblity to add more storage engines that
could use galera replication.
mysqldump:
- Added --log-queries to allow one to disable logging for the dump
sql/log_event.cc:
- Removed setting of enable_slow_log as it's not required anymore.
sql/sql_parse.cc:
- Set enable_slow_log to value of thd->variables.sql_log_slow as this will speed up tests if slow log is disabled.
- opt_log_slow_admin_statements can now only disable slow log, not enable it.
sql/sql_explain.cc:
- Minor cleanup
Other things:
- Added sql_log_slow to system variables.
- Changed opt_slow_log to global_system_variables.sql_log_slow in all files
- Updated tests to reflect changes
config.h.cmake:
define NOMINMAX, otherwise Windows system headers define min() and max() macros
sql/slave.cc:
mi->report() has one more argument in MariaDB
storage/xtradb/buf/buf0flu.cc:
xtradb fixes for windows, again
Fix the bug properly (plugin cannot be unloaded as long as it's locked).
Enable and fix the test case.
Significantly reduce number of LOCK_plugin locks for semisync
(practically all locks were removed)
Merge the patches into MariaDB 10.0 main.
With this patch, parallel replication will now automatically retry a
transaction that fails due to deadlock or other temporary error, same as
single-threaded replication.
We catch deadlocks with InnoDB transactions due to enforced commit order. If
T1 must commit before T2 in parallel replication and T1 ends up waiting for T2
inside InnoDB, we kill T2 and retry it later to resolve the deadlock
automatically.
Fix a bug discovered in Buildbot valgrind. The logic in checking for slave
init thread completion was reversed, so depending on thread scheduling server
startup could hang.
Also add another variant of SSL valgrind suppression, needed for different
library version.
After-review changes.
For this patch in 10.0, we do not introduce a new public storage engine API,
we just fix the InnoDB/XtraDB issues. In 10.1, we will make a better public
API that can be used for all storage engines (MDEV-6429).
Eliminate the background thread that did deadlock kills asynchroneously.
Instead, we ensure that the InnoDB/XtraDB code can handle doing the kill from
inside the deadlock detection code (when thd_report_wait_for() needs to kill a
later thread to resolve a deadlock).
(We preserve the part of the original patch that introduces dedicated mutex
and condition for the slave init thread, to remove the abuse of
LOCK_thread_count for start/stop synchronisation of the slave init thread).
The sql_slave_skip_counter is important to be able to recover replication from
certain errors. Often, an appropriate solution is to set
sql_slave_skip_counter to skip over a problem event. But setting
sql_slave_skip_counter produced an error in GTID mode, with a suggestion to
instead set @@gtid_slave_pos to point past the problem event. This however is
not always possible; for example, in case of an INCIDENT event, that event
does not have any GTID to assign to @@gtid_slave_pos.
With this patch, sql_slave_skip_counter now works in GTID mode the same was as
in non-GTID mode. When set, that many initial events are skipped when the SQL
thread starts, plus as many extra events are needed to completely skip any
partially skipped event group. The GTID position is updated to point past the
skipped event(s).
If replication breaks in GTID mode, it is not trivial to determine the GTID of
the failing event group. This is a problem, as such GTID is needed eg. to
explicitly set @@gtid_slave_pos to skip to after that event group, or to
compare errors on different servers, etc.
Fix by ensuring that relevant slave errors logged to the error log include the
GTID of the event group containing the problem event.
Preserve CLIENT_REMEMBER_OPTIONS flag for compressed connections
Code cleanup: removed reference to CLIENT_REMEMBER_OPTIONS from server
code. This flag is ignored in MariaDB.
That particular part of slave connect to master was missing code to handle
retry in case of network errors. The same problem is present in MySQL 5.5, but
fixed in MySQL 5.6.
Fixed with this patch, by adding the code (mostly identical to MySQL 5.6), and
also adding a test case.
I checked other queries done towards master during slave connect, and they now
all seem to handle reconnect in case of network failures.
replication causing replication to fail.
Remove the temporary fix for MDEV-5914, which used READ COMMITTED for parallel
replication worker threads. Replace it with a better, more selective solution.
The issue is with certain edge cases of InnoDB gap locks, for example between
INSERT and ranged DELETE. It is possible for the gap lock set by the DELETE to
block the INSERT, if the DELETE runs first, while the record lock set by
INSERT does not block the DELETE, if the INSERT runs first. This can cause a
conflict between the two in parallel replication on the slave even though they
ran without conflicts on the master.
With this patch, InnoDB will ask the server layer about the two involved
transactions before blocking on a gap lock. If the server layer tells InnoDB
that the transactions are already fixed wrt. commit order, as they are in
parallel replication, InnoDB will ignore the gap lock and allow the two
transactions to proceed in parallel, avoiding the conflict.
Improve the fix for MDEV-6020. When InnoDB itself detects a deadlock, it now
asks the server layer for any preferences about which transaction to roll
back. In case of parallel replication with two transactions T1 and T2 fixed to
commit T1 before T2, the server layer will ask InnoDB to roll back T2 as the
deadlock victim, not T1. This helps in some cases to avoid excessive deadlock
rollback, as T2 will in any case need to wait for T1 to complete before it can
itself commit.
Also some misc. fixes found during development and testing:
- Remove thd_rpl_is_parallel(), it is not used or needed.
- Use KILL_CONNECTION instead of KILL_QUERY when a parallel replication
worker thread is killed to resolve a deadlock with fixed commit
ordering. There are some cases, eg. in sql/sql_parse.cc, where a KILL_QUERY
can be ignored if the query otherwise completed successfully, and this
could cause the deadlock kill to be lost, so that the deadlock was not
correctly resolved.
- Fix random test failure due to missing wait_for_binlog_checkpoint.inc.
- Make sure that deadlock or other temporary errors during parallel
replication are not printed to the the error log; there were some places
around the replication code with extra error logging. These conditions can
occur occasionally and are handled automatically without breaking
replication, so they should not pollute the error log.
- Fix handling of rgi->gtid_sub_id. We need to be able to access this also at
the end of a transaction, to be able to detect and resolve deadlocks due to
commit ordering. But this value was also used as a flag to mark whether
record_gtid() had been called, by being set to zero, losing the value. Now,
introduce a separate flag rgi->gtid_pending, so rgi->gtid_sub_id remains
valid for the entire duration of the transaction.
- Fix one place where the code to handle ignored errors called reset_killed()
unconditionally, even if no error was caught that should be ignored. This
could cause loss of a deadlock kill signal, breaking deadlock detection and
resolution.
- Fix a couple of missing mysql_reset_thd_for_next_command(). This could
cause a prior error condition to remain for the next event executed,
causing assertions about errors already being set and possibly giving
incorrect error handling for following event executions.
- Fix code that cleared thd->rgi_slave in the parallel replication worker
threads after each event execution; this caused the deadlock detection and
handling code to not be able to correctly process the associated
transactions as belonging to replication worker threads.
- Remove useless error code in slave_background_kill_request().
- Fix bug where wfc->wakeup_error was not cleared at
wait_for_commit::unregister_wait_for_prior_commit(). This could cause the
error condition to wrongly propagate to a later wait_for_prior_commit(),
causing spurious ER_PRIOR_COMMIT_FAILED errors.
- Do not put the binlog background thread into the processlist. It causes
too many result differences in mtr, but also it probably is not useful
for users to pollute the process list with a system thread that does not
really perform any user-visible tasks...
replication causing replication to fail.
In parallel replication, we run transactions from the master in parallel, but
force them to commit in the same order they did on the master. If we force T1
to commit before T2, but T2 holds eg. a row lock that is needed by T1, we get
a deadlock when T2 waits until T1 has committed.
Usually, we do not run T1 and T2 in parallel if there is a chance that they
can have conflicting locks like this, but there are certain edge cases where
it can occasionally happen (eg. MDEV-5914, MDEV-5941, MDEV-6020). The bug was
that this would cause replication to hang, eventually getting a lock timeout
and causing the slave to stop with error.
With this patch, InnoDB will report back to the upper layer whenever a
transactions T1 is about to do a lock wait on T2. If T1 and T2 are parallel
replication transactions, and T2 needs to commit later than T1, we can thus
detect the deadlock; we then kill T2, setting a flag that causes it to catch
the kill and convert it to a deadlock error; this error will then cause T2 to
roll back and release its locks (so that T1 can commit), and later T2 will be
re-tried and eventually also committed.
The kill happens asynchroneously in a slave background thread; this is
necessary, as the reporting from InnoDB about lock waits happen deep inside
the locking code, at a point where it is not possible to directly call
THD::awake() due to mutexes held.
Deadlock is assumed to be (very) rarely occuring, so this patch tries to
minimise the performance impact on the normal case where no deadlocks occur,
rather than optimise the handling of the occasional deadlock.
Also fix transaction retry due to deadlock when it happens after a transaction
already signalled to later transactions that it started to commit. In this
case we need to undo this signalling (and later redo it when we commit again
during retry), so following transactions will not start too early.
Also add a missing thd->send_kill_message() that got triggered during testing
(this corrects an incorrect fix for MySQL Bug#58933).
Handle retry of event groups that span multiple relay log files.
- If retry reaches the end of one relay log file, move on to the next.
- Handle refcounting of relay log files, and avoid purging relay log
files until all event groups have completed that might have needed
them for transaction retry.
SHOW PROCESSLIST, SHOW BINLOGS
Problem: A deadlock was occurring when 4 threads were
involved in acquiring locks in the following way
Thread 1: Dump thread ( Slave is reconnecting, so on
Master, a new dump thread is trying kill
zombie dump threads. It acquired thread's
LOCK_thd_data and it is about to acquire
mysys_var->current_mutex ( which LOCK_log)
Thread 2: Application thread is executing show binlogs and
acquired LOCK_log and it is about to acquire
LOCK_index.
Thread 3: Application thread is executing Purge binary logs
and acquired LOCK_index and it is about to
acquire LOCK_thread_count.
Thread 4: Application thread is executing show processlist
and acquired LOCK_thread_count and it is
about to acquire zombie dump thread's
LOCK_thd_data.
Deadlock Cycle:
Thread 1 -> Thread 2 -> Thread 3-> Thread 4 ->Thread 1
The same above deadlock was observed even when thread 4 is
executing 'SELECT * FROM information_schema.processlist' command and
acquired LOCK_thread_count and it is about to acquire zombie
dump thread's LOCK_thd_data.
Analysis:
There are four locks involved in the deadlock. LOCK_log,
LOCK_thread_count, LOCK_index and LOCK_thd_data.
LOCK_log, LOCK_thread_count, LOCK_index are global mutexes
where as LOCK_thd_data is local to a thread.
We can divide these four locks in two groups.
Group 1 consists of LOCK_log and LOCK_index and the order
should be LOCK_log followed by LOCK_index.
Group 2 consists of other two mutexes
LOCK_thread_count, LOCK_thd_data and the order should
be LOCK_thread_count followed by LOCK_thd_data.
Unfortunately, there is no specific predefined lock order defined
to follow in the MySQL system when it comes to locks across these
two groups. In the above problematic example,
there is no problem in the way we are acquiring the locks
if you see each thread individually.
But If you combine all 4 threads, they end up in a deadlock.
Fix:
Since everything seems to be fine in the way threads are taking locks,
In this patch We are changing the duration of the locks in Thread 4
to break the deadlock. i.e., before the patch, Thread 4
('show processlist' command) mysqld_list_processes()
function acquires LOCK_thread_count for the complete duration
of the function and it also acquires/releases
each thread's LOCK_thd_data.
LOCK_thread_count is used to protect addition and
deletion of threads in global threads list. While show
process list is looping through all the existing threads,
it will be a problem if a thread is exited but there is no problem
if a new thread is added to the system. Hence a new mutex is
introduced "LOCK_thd_remove" which will protect deletion
of a thread from global threads list. All threads which are
getting exited should acquire LOCK_thd_remove
followed by LOCK_thread_count. (It should take LOCK_thread_count
also because other places of the code still thinks that exit thread
is protected with LOCK_thread_count. In this fix, we are changing
only 'show process list' query logic )
(Eg: unlink_thd logic will be protected with
LOCK_thd_remove).
Logic of mysqld_list_processes(or file_schema_processlist)
will now be protected with 'LOCK_thd_remove' instead of
'LOCK_thread_count'.
Now the new locking order after this patch is:
LOCK_thd_remove -> LOCK_thd_data -> LOCK_log ->
LOCK_index -> LOCK_thread_count
Start implementing that an event group can be re-tried in parallel replication
if it fails with a temporary error (like deadlock).
Patch is very incomplete, just some very basic retry works.
Stuff still missing (not complete list):
- Handle moving to the next relay log file, if event group to be retried
spans multiple relay log files.
- Handle refcounting of relay log files, to ensure that we do not purge a
relay log file and then later attempt to re-execute events out of it.
- Handle description_event_for_exec - we need to save this somehow for the
possible retry - and use the correct one in case it differs between relay
logs.
- Do another retry attempt in case the first retry also fails.
- Limit the max number of retries.
- Lots of testing will be needed for the various edge cases.
The previous patch for this bug was unfortunately completely wrong.
The purpose of cached_charset is to remember which character set we
have installed currently in the THD, so that in the common case where
charset does not change between queries, we do not need to update it
in the THD. Thus, it is important that the cached_charset field is
tightly coupled to the THD for which it handles caching.
Thus the right place to put cached_charset seems to be in the THD.
This patch introduces a field THD:system_thread_info where such info
in general can be placed without further inflating the THD with unused
data for other threads (THD is already far too big as it is). It then
moves the cached_charset into this slot for the SQL driver thread and
for the parallel replication worker threads.
The THD::rpl_filter field is also moved inside system_thread_info, to
keep the size of THD unchanged. Moving further fields in to reduce the
size of THD is a separate task, filed as MDEV-6164.
Replication caches the character sets used in a query, to be able to quickly
reuse them for the next query in the common case of them not having changed.
In parallel replication, this caching needs to be per-worker-thread. The
code was not modified to handle this correctly, so the caching in one worker
could cause another worker to run a query using the wrong character set,
causing replication corruption.
We need to use mysql_cond_broadcast() rather than _signal for
COND_thread_count, as there can be multiple waiters.
Thanks to Pavel Ivanov for reporting both the problem and the
solution.
Reason for the bug was an optimization for higher connect speed where we moved when global status was updated,
but forgot to update states when slave thread dies.
Fixed by adding thd->add_status_to_global() before deleting slave thread's thd.
mysys/my_delete.c:
Added missing newline
sql/mysqld.cc:
Use add_status_to_global()
sql/slave.cc:
Added missing add_status_to_global()
sql/sql_class.cc:
Use add_status_to_global()
sql/sql_class.h:
Simplify adding local status to global by adding add_status_to_global()
Before, the arrival of same GTID twice in multi-source replication
would cause double-apply or in gtid strict mode an error.
Keep the behaviour, but add an option --gtid-ignore-duplicates which
allows to correctly handle duplicates, ignoring all but the first.
This relies on the user ensuring correct configuration so that
sequence numbers are strictly increasing within each replication
domain; then duplicates can be detected simply by comparing the
sequence numbers against what is already applied.
Only one master connection (but possibly multiple parallel worker
threads within that connection) is allowed to apply events within
one replication domain at a time; any other connection that
receives a GTID in the same domain either discards it (if it is
already applied) or waits for the other connection to not have
any events to apply.
Intermediate patch, as proof-of-concept for testing. The main limitation
is that currently it is only implemented for parallel replication,
@@slave_parallel_threads > 0.
Older master has no GTID events, so such events are not available for
deciding on scheduling of event groups and so on.
With this patch, we run such events from old masters single-threaded, in the
sql driver thread.
This seems better than trying to make the parallel code handle the data from
older masters; while possible, this would require a lot of testing (as well as
possibly some extra overhead in the scheduling of events), which hardly seems
worthwhile.
With parallel replication, there can be any number of events queued on
in-memory lists in the worker threads.
For normal STOP SLAVE, we want to skip executing any remaining events on those
lists and stop as quickly as possible.
However, for START SLAVE UNTIL, when the UNTIL position is reached in the SQL
driver thread, we must _not_ stop until all already queued events for the
workers have been executed - otherwise we would stop too early, before the
actual UNTIL position had been completely reached.
The code did not handle UNTIL correctly, stopping too early due to not
executing the queued events to completion. Fix this, and also implement that
an explicit STOP SLAVE in the middle (when the SQL driver thread has reached
the UNTIL position but the workers have not) _will_ cause an immediate stop.
