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Fix for MDEV-9679 main.delayed fails sporadically

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Problem was that notify_shared_lock() didn't abort an insert delayed thread
if it was in thr_upgrade_write_delay_lock().

ALTER TABLE first takes a weak_mdl_lock, then a thr_lock and then tries to upgrade
the mdl_lock.
Delayed insert thread first takes a mdl lock followed by a
thr_upgrade_write_delay_lock()
This caused insert delay to wait for alter table in thr_lock, while
alter table was waiting for the mdl lock by insert delay.

Fixed by telling mdl to run thr_lock_abort() for the insert delay thread table.
We also set thd->mysys_var->abort to 1 for the delay thread when it's killed
by alter table to ensure it doesn't ever get locked in thr_lock.
This commit is contained in:
Monty
2016-04-26 12:22:02 +03:00
parent f6cc7f1bdc
commit 0dbc66498d
2 changed files with 64 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

55
sql/sql_class.cc
View File

@@ -1878,38 +1878,55 @@ bool THD::notify_shared_lock(MDL_context_owner *ctx_in_use,
{
THD *in_use= ctx_in_use->get_thd();
bool signalled= FALSE;
DBUG_ENTER("THD::notify_shared_lock");
DBUG_PRINT("enter",("needs_thr_lock_abort: %d", needs_thr_lock_abort));
if ((in_use->system_thread & SYSTEM_THREAD_DELAYED_INSERT) &&
!in_use->killed)
{
in_use->killed= KILL_CONNECTION;
mysql_mutex_lock(&in_use->mysys_var->mutex);
if (in_use->mysys_var->current_cond)
mysql_cond_broadcast(in_use->mysys_var->current_cond);
mysql_mutex_unlock(&in_use->mysys_var->mutex);
/* This code is similar to kill_delayed_threads() */
DBUG_PRINT("info", ("kill delayed thread"));
mysql_mutex_lock(&in_use->LOCK_thd_data);
if (in_use->killed < KILL_CONNECTION)
in_use->killed= KILL_CONNECTION;
if (in_use->mysys_var)
{
mysql_mutex_lock(&in_use->mysys_var->mutex);
if (in_use->mysys_var->current_cond)
mysql_cond_broadcast(in_use->mysys_var->current_cond);
/* Abort if about to wait in thr_upgrade_write_delay_lock */
in_use->mysys_var->abort= 1;
mysql_mutex_unlock(&in_use->mysys_var->mutex);
}
mysql_mutex_unlock(&in_use->LOCK_thd_data);
signalled= TRUE;
}
if (needs_thr_lock_abort)
{
mysql_mutex_lock(&in_use->LOCK_thd_data);
for (TABLE *thd_table= in_use->open_tables;
thd_table ;
thd_table= thd_table->next)
/* If not already dying */
if (in_use->killed != KILL_CONNECTION_HARD)
{
/*
Check for TABLE::needs_reopen() is needed since in some places we call
handler::close() for table instance (and set TABLE::db_stat to 0)
and do not remove such instances from the THD::open_tables
for some time, during which other thread can see those instances
(e.g. see partitioning code).
*/
if (!thd_table->needs_reopen())
signalled|= mysql_lock_abort_for_thread(this, thd_table);
for (TABLE *thd_table= in_use->open_tables;
thd_table ;
thd_table= thd_table->next)
{
/*
Check for TABLE::needs_reopen() is needed since in some
places we call handler::close() for table instance (and set
TABLE::db_stat to 0) and do not remove such instances from
the THD::open_tables for some time, during which other
thread can see those instances (e.g. see partitioning code).
*/
if (!thd_table->needs_reopen())
signalled|= mysql_lock_abort_for_thread(this, thd_table);
}
mysql_mutex_unlock(&in_use->LOCK_thd_data);
}
mysql_mutex_unlock(&in_use->LOCK_thd_data);
}
return signalled;
DBUG_RETURN(signalled);
}