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MDEV-7943 - pthread_getspecific() takes 0.76% in OLTP RO

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Avoid calling current_thd from thd_kill_level(). This reduces number of
pthread_getspecific() calls from 776 to 354.

Also thd_kill_level(NULL) is not permitted anymore: this saves one condition.
This commit is contained in:
Sergey Vojtovich
2015-04-22 14:18:51 +04:00
parent f8cacd03a7
commit 18f88d6d94
2 changed files with 20 additions and 13 deletions
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29
sql/sql_class.cc
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@@ -4205,23 +4205,30 @@ extern "C" int thd_killed(const MYSQL_THD thd)
/*
return thd->killed status to the client,
mapped to the API enum thd_kill_levels values.
@note Since this function is called quite frequently thd_kill_level(NULL) is
forbidden for performance reasons (saves one conditional branch). If your ever
need to call thd_kill_level() when THD is not available, you options are (most
to least preferred):
- try to pass THD through to thd_kill_level()
- add current_thd to some service and use thd_killed(current_thd)
- add thd_killed_current() function to kill statement service
- add if (!thd) thd= current_thd here
*/
extern "C" enum thd_kill_levels thd_kill_level(const MYSQL_THD thd)
{
THD* current= current_thd;
if (!thd)
thd= current;
if (thd == current)
{
Apc_target *apc_target= (Apc_target*)&thd->apc_target;
if (apc_target->have_apc_requests())
apc_target->process_apc_requests();
}
DBUG_ASSERT(thd);
if (likely(thd->killed == NOT_KILLED))
{
Apc_target *apc_target= (Apc_target*) &thd->apc_target;
if (unlikely(apc_target->have_apc_requests()))
{
if (thd == current_thd)
apc_target->process_apc_requests();
}
return THD_IS_NOT_KILLED;
}
return thd->killed & KILL_HARD_BIT ? THD_ABORT_ASAP : THD_ABORT_SOFTLY;
}