The upper 1M limit for max_prepared_stmt_count was set over 10 years
ago. It doesn't suite current hardware and a sysbench oltp_read_write
test with 512 threads will hit this limit.
Applied lost in a merge revision 7f38a07:
MDEV-10043 - main.events_restart fails sporadically in buildbot (crashes upon
shutdown)
There was race condition between shutdown thread and event worker threads.
Shutdown thread waits for thread_count to become 0 in close_connections(). It
may happen so that event worker thread was started but didn't increment
thread_count by this time. In this case shutdown thread may miss wait for this
working thread and continue deinitialization. Worker thread in turn may continue
execution and crash on deinitialized data.
Fixed by incrementing thread_count before thread is actually created like it is
done for connection threads.
Also let event scheduler not to inc/dec running threads counter for symmetry
with other "service" threads.
- Fixed typos
- Added --core-on-failure to mysql-test-run
- More DBUG_PRINT in viosocket.c
- Don't forget CLIENT_REMEMBER_OPTIONS for compressed slave protocol
- Removed not used stage variables
GENERATED BY THE EXP() FUNCTION
When generating the error message for numeric overflow, pass a flag to
Item::print() that prevents it from expanding constant expressions and
parameters to the values they evaluate to.
For consistency, also pass the flag to Item::print() when
Item_func_spatial_collection::fix_length_and_dec() generates an error
message. It doesn't make any difference at the moment, since constant
expressions haven't been evaluated yet when this function is called.
Problem was that we used same condition variable with 2 different mutex.
Fixed by changing to use COND_rpl_thread_stop instead of COND_parallel_entry
for stopping threads.
Patch by Kristian Nielsen
Problem is that FLUSH TABLES WITH READ LOCK first blocks threads from
starting new commits, then waits for running commits to complete. But
in-order parallel replication needs commits to happen in a particular
order, so this can easily deadlock.
To fix this problem, this patch introduces a way to temporarily pause
the parallel replication worker threads. Before starting FTWRL, we let
all worker threads complete in-progress transactions, and then
wait. Then we proceed to take the global read lock. Once the lock is
obtained, we unpause the worker threads. Now commits are blocked from
starting by the global read lock, so the deadlock will no longer occur.
Patch backported from MariaDB 10.1
- Ensure that we wait with cleanup() until slave thread has stopped.
- Added signal_thd_deleted() to signal close_connections() that all THD's has been freed.
Other things
- Removed not needed calls to THD_CHECK_SENTRY() when we are calling 'delete thd'.
Description: The command FLUSH DES_KEY_FILE is expected to
reload the DES keys from the file that was specified with
the "--des-key-file" option at server startup. But it is not
behaving as expected.
Analysis: The des file reload is defined within a wrong
conditional directive, rendering the command ineffective.
Macro "OPENSSL" was used instead of "HAVE_OPENSSL" macro.
Fix: "OPENSSL" macro is changed to "HAVE_OPENSSL".
When the slave processes the master restart format_description event,
parallel replication needs to complete any prior events before processing
the restart event (which closes temporary tables and such stuff).
This happens in wait_for_workers_idle(), however it was not waiting long
enough. The wait was using wait_for_prior_commit(), but at that points table
can still be open. This lead to assertion in this case.
So change wait_for_workers_idle() to wait until all worker threads have
reached finish_event_group(), at which point all tables should have been
closed.
including the big commit
commit 305130361bf72726de220f3d2b2787395e10be61
Author: Marc Alff <marc.alff@oracle.com>
Date: Tue Feb 10 11:31:32 2015 +0100
WL#8354 BACKPORT DIGEST IMPROVEMENTS TO MYSQL 5.6
(with the following commits) and related changes in sql/
Stage "Filling schema table" is now properly shown in 'show processlist'
mysys/mf_keycache.c:
Simple cleanup with more comments
sql/lock.cc:
Return to original stage after mysql_lock_tables
Made 'Table lock' as a true stage
sql/sql_show.cc:
Restore original stage after get_schema_tables_result
In parallel replication, threads can do two different waits for a prior
transaction. One is for the prior transaction to start commit, the other is
for it to complete commit.
It turns out that the same PSI_stage_info message was errorneously used in
both cases (probably a merge error), causing SHOW PROCESSLIST to be
misleading.
Fix by using correct, distinct message in each case.
Instead we use LOCK_status only to protect summary of thread statistics and use a new mutex, LOCK_show_status
to protect concurrent SHOW STATUS.
sql/mysqld.cc:
Add LOCK_show_status
Don't free LOCK_status while calculating status variables.
sql/mysqld.h:
Add LOCK_show_status
sql/sql_show.cc:
Use LOCK_show_status to protect SHOW STATUS instead of LOCK_status.
Reason for the problem was that the hash of changed files in the key cache was too small (was 128). Fixed by making the hash size larger and changeable.
- Introduced key-cache-file-hash-size (default 512) for MyISAM and aria_pagecache_file_hash_size (default 512) for Aria.
- Added new status variable "Feature_delay_key_write" which counts number of tables opened that are using delay_key_write
mysql-test/r/features.result:
Added test of Feature_delay_key_write
mysql-test/r/key_cache.result:
Updated tests as the number of blocks has changed
mysql-test/r/mysqld--help.result:
Updated result
mysql-test/suite/maria/maria3.result:
Updated result
mysql-test/suite/sys_vars/r/key_cache_file_hash_size_basic.result:
Test new variable
mysql-test/suite/sys_vars/t/aria_pagecache_file_hash_size_basic.test:
Test new variable
mysql-test/suite/sys_vars/t/key_cache_file_hash_size_basic.test:
Test new variable
mysql-test/t/features.test:
Added test of Feature_delay_key_write
mysql-test/t/key_cache.test:
Updated tests as the number of blocks has changed
mysys/mf_keycache.c:
Made CHANGED_BLOCKS_HASH dynamic
sql/handler.cc:
Updated call to init_key_cache()
sql/mysqld.cc:
Added "Feature_delay_key_write"
Added support for key-cache-file-hash-size
sql/mysqld.h:
Added support for key-cache-file-hash-size
sql/sql_class.h:
Added feature_files_opened_with_delayed_keys
sql/sys_vars.cc:
Added key_cache_file_hash_size
storage/maria/ha_maria.cc:
Added pagecache_file_hash_size
Added counting of files with delay_key_write
storage/maria/ma_checkpoint.c:
Fixed compiler warning
storage/maria/ma_pagecache.c:
Made PAGECACHE_CHANGED_BLOCKS_HASH into a variable
storage/maria/ma_pagecache.h:
Made PAGECACHE_CHANGED_BLOCKS_HASH into a variable
storage/maria/ma_rt_test.c:
Updated parameters for init_pagecache()
storage/maria/ma_test1.c:
Updated parameters for init_pagecache()
storage/maria/ma_test2.c:
Updated parameters for init_pagecache()
storage/maria/ma_test3.c:
Updated parameters for init_pagecache()
storage/maria/maria_chk.c:
Updated parameters for init_pagecache()
storage/maria/maria_ftdump.c:
Updated parameters for init_pagecache()
storage/maria/maria_pack.c:
Updated parameters for init_pagecache()
storage/maria/maria_read_log.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_pagecache_consist.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_pagecache_rwconsist.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_pagecache_rwconsist2.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_pagecache_single.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_first_lsn-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_max_lsn-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_multigroup-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_multithread-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_noflush-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_nologs-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_pagecache-t.c:
Updated parameters for init_pagecache()
storage/maria/unittest/ma_test_loghandler_purge-t.c:
Updated parameters for init_pagecache()
storage/myisam/ha_myisam.cc:
Added counting of files with delay_key_write
storage/myisam/mi_check.c:
Updated call to init_key_cache()
storage/myisam/mi_test1.c:
Updated call to init_key_cache()
storage/myisam/mi_test2.c:
Updated call to init_key_cache()
storage/myisam/mi_test3.c:
Updated call to init_key_cache()
storage/myisam/mi_test_all.sh:
Fixed broken test
storage/myisam/myisam_ftdump.c:
Updated call to init_key_cache()
storage/myisam/myisamchk.c:
Updated call to init_key_cache()
storage/myisam/myisamlog.c:
Updated call to init_key_cache()
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).
Description:
THREAD_CONCURRENCY is deprecated and there is no
deprecation warning message while setting this variable
while starting the server.
Analysis:
This variable is specific to Solaris 8 and earlier systems
and is ignored on all other platforms. But since many
customers, who uses other than Solaris, still has this
variable in their configuration file, it is important to
have a deprecation warning.
Fix:
THREAD_CONCURRENCY deprecation warning message is added.
Description:
THREAD_CONCURRENCY is deprecated and there is no
deprecation warning message while setting this variable
while starting the server.
Analysis:
This variable is specific to Solaris 8 and earlier systems
and is ignored on all other platforms. But since many
customers, who uses other than Solaris, still has this
variable in their configuration file, it is important to
have a deprecation warning.
Fix:
THREAD_CONCURRENCY deprecation warning message is added.
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).
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
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
committer: Christopher Powers <chris.powers@oracle.com>
branch nick: mysql-5.6-bug16750433
timestamp: Fri 2013-06-28 07:48:12 -0500
message:
Bug#16750433 - THE STATEMENT DIGEST DOES NOT SHOW THE SLAVE SQL
THREAD STATEMENTS
revno: 5414.1.1
committer: Marc Alff <marc.alff@oracle.com>
branch nick: mysql-5.6-bug17271055
timestamp: Thu 2013-08-29 12:29:25 +0200
message:
Bug#17271055 "STATEMENT/COM" EVENT MEANING IS UNCLEAR
(test case was merged with perfschema 5.6.17)
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.
Clean up and improve the parallel implementation code, mainly related to
scheduling of work to threads and handling of stop and errors.
Fix a lot of bugs in various corner cases that could lead to crashes or
corruption.
Fix that a single replication domain could easily grab all worker threads and
stall all other domains; now a configuration variable
--slave-domain-parallel-threads allows to limit the number of
workers.
Allow next event group to start as soon as previous group begins the commit
phase (as opposed to when it ends it); this allows multiple event groups on
the slave to participate in group commit, even when no other opportunities for
parallelism are available.
Various fixes:
- Fix some races in the rpl.rpl_parallel test case.
- Fix an old incorrect assertion in Log_event iocache read.
- Fix repeated malloc/free of wait_for_commit and rpl_group_info objects.
- Simplify wait_for_commit wakeup logic.
- Fix one case in queue_for_group_commit() where killing one thread would
fail to correctly signal the error to the next, causing loss of the
transaction after slave restart.
- Fix leaking of pthreads (and their allocated stack) due to missing
PTHREAD_CREATE_DETACHED attribute.
- Fix how one batch of group-committed transactions wait for the previous
batch before starting to execute themselves. The old code had a very
complex scheduling where the first transaction was handled differently,
with subtle bugs in corner cases. Now each event group is always scheduled
for a new worker (in a round-robin fashion amongst available workers).
Keep a count of how many transactions have started to commit, and wait for
that counter to reach the appropriate value.
- Fix slave stop to wait for all workers to actually complete processing;
before, the wait was for update of last_committed_sub_id, which happens a
bit earlier, and could leave worker threads potentially accessing bits of
the replication state that is no longer valid after slave stop.
- Fix a couple of places where the test suite would kill a thread waiting
inside enter_cond() in connection with debug_sync; debug_sync + kill can
crash in rare cases due to a race with mysys_var_current_mutex in this
case.
- Fix some corner cases where we had enter_cond() but no exit_cond().
- Fix that we could get failure in wait_for_prior_commit() but forget to flag
the error with my_error().
- Fix slave stop (both for normal stop and stop due to error). Now, at stop
we pick a specific safe point (in terms of event groups executed) and make
sure that all event groups before that point are executed to completion,
and that no event group after start executing; this ensures a safe place to
restart replication, even for non-transactional stuff/DDL. In error stop,
make sure that all prior event groups are allowed to execute to completion,
and that any later event groups that have started are rolled back, if
possible. The old code could leave eg. T1 and T3 committed but T2 not, or
it could even leave half a transaction not rolled back in some random
worker, which would cause big problems when that worker was later reused
after slave restart.
- Fix the accounting of amount of events queued for one worker. Before, the
amount was reduced immediately as soon as the events were dequeued (which
happens all at once); this allowed twice the amount of events to be queued
in memory for each single worker, which is not what users would expect.
- Fix that an error set during execution of one event was sometimes not
cleared before executing the next, causing problems with the error
reporting.
- Fix incorrect handling of thd->killed in worker threads.
MASTER_GTID_WAIT() is similar to MASTER_POS_WAIT(), but works with a
GTID position rather than an old-style filename/offset.
@@LAST_GTID gives the GTID assigned to the last transaction written
into the binlog.
Together, the two can be used by applications to obtain the GTID of
an update on the master, and then do a MASTER_GTID_WAIT() for that
position on any read slave where it is important to get results that
are caught up with the master at least to the point of the update.
The implementation of MASTER_GTID_WAIT() is implemented in a way
that tries to minimise the performance impact on the SQL threads,
even in the presense of many waiters on single GTID positions (as
from @@LAST_GTID).
