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Move all kill mutex protection to LOCK_thd_kill

Browse Source 
LOCK_thd_data was used to protect both THD data and
ensure that the THD is not deleted while it was in use

This patch moves the THD delete protection to LOCK_thd_kill,
which already protects the THD for kill.

The benefits are:
- More well defined what LOCK_thd_data protects
- LOCK_thd_data usage is now much simpler and easier to verify
- Less chance of deadlocks in SHOW PROCESS LIST as there is less
  chance of interactions between mutexes
- Remove not needed LOCK_thread_count from
  thd_get_error_context_description()
- Fewer mutex taken for thd->awake()

Other things:
- Don't take mysys->var mutex in show processlist to check if thread
  is kill marked
- thd->awake() now automatically takes the LOCK_thd_kill mutex
  (Simplifies code)
- Apc uses LOCK_thd_kill instead of LOCK_thd_data
This commit is contained in:
Monty
2017-12-07 21:28:00 +02:00
parent 3574f9c7bc
commit c2118a08b1
15 changed files with 109 additions and 120 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
sql/sql_insert.cc
View File

@ -2702,9 +2702,9 @@ void kill_delayed_threads(void)
Delayed_insert *di;
while ((di= it++))
{
mysql_mutex_lock(&di->thd.LOCK_thd_data);
mysql_mutex_lock(&di->thd.LOCK_thd_kill);
if (di->thd.killed < KILL_CONNECTION)
di->thd.set_killed(KILL_CONNECTION);
di->thd.set_killed_no_mutex(KILL_CONNECTION);
if (di->thd.mysys_var)
{
mysql_mutex_lock(&di->thd.mysys_var->mutex);
@ -2722,7 +2722,7 @@ void kill_delayed_threads(void)
}
mysql_mutex_unlock(&di->thd.mysys_var->mutex);
}
mysql_mutex_unlock(&di->thd.LOCK_thd_data);
mysql_mutex_unlock(&di->thd.LOCK_thd_kill);
}
mysql_mutex_unlock(&LOCK_delayed_insert); // For unlink from list
DBUG_VOID_RETURN;
@ -3076,9 +3076,9 @@ pthread_handler_t handle_delayed_insert(void *arg)
this.
*/
mysql_mutex_lock(&thd->LOCK_thd_data);
thd->set_killed(KILL_CONNECTION_HARD); // If error
thd->mdl_context.set_needs_thr_lock_abort(0);
mysql_mutex_unlock(&thd->LOCK_thd_data);
thd->set_killed(KILL_CONNECTION_HARD); // If error
close_thread_tables(thd); // Free the table
thd->mdl_context.release_transactional_locks();