Re: [Maria-developers] [Commits] 7320cbf: MDEV-7177 - Server hangs on shutdown after InnoDB error (main.plugin_loaderr
Hi, Sergey! On Feb 02, svoj@mariadb.org wrote:
revision-id: 7320cbf85ddfaf7ef76c8f03718819377fd14318 parent(s): 11deb416fe12ebfd65a1f089c7eb6087c192e2dd committer: Sergey Vojtovich branch nick: 10.1 timestamp: 2015-02-02 15:41:49 +0400 message:
MDEV-7177 - Server hangs on shutdown after InnoDB error (main.plugin_loaderr fails in buildbot)
There was a race condition in timer functionality of query timeouts.
Race was as following: main thread: init_thr_timers() timer handler thread: my_thread_init() main thread: end_thr_timer()/timer_thread_state= ABORTING timer handler thread: timer_thread_state= RUNNING, continue normal op main thread: waits indefinitely for timer handler thread to go down
The original idea of the fix is to set RUNNING state in main thread, before starting timer handler thread. But it didn't survive further cleanups: - removed "timer_thread_state" and used "thr_timer_inited" for this purpose - removed unused "timer_thread_running" - removed code responisble for "timer handler thread" shutdown synchronization, use pthread_join() instead.
That looks ok to me. The only concern is - in end_thr_timer(), the old code had a timeout waiting for a timer thread to die. pthread_join() doesn't. I don't know if that's a problem, perhaps not. Regards, Sergei
Hi Sergei, thanks for your review. On Wed, Feb 04, 2015 at 07:58:53PM +0100, Sergei Golubchik wrote:
Hi, Sergey!
On Feb 02, svoj@mariadb.org wrote:
revision-id: 7320cbf85ddfaf7ef76c8f03718819377fd14318 parent(s): 11deb416fe12ebfd65a1f089c7eb6087c192e2dd committer: Sergey Vojtovich branch nick: 10.1 timestamp: 2015-02-02 15:41:49 +0400 message:
MDEV-7177 - Server hangs on shutdown after InnoDB error (main.plugin_loaderr fails in buildbot)
There was a race condition in timer functionality of query timeouts.
Race was as following: main thread: init_thr_timers() timer handler thread: my_thread_init() main thread: end_thr_timer()/timer_thread_state= ABORTING timer handler thread: timer_thread_state= RUNNING, continue normal op main thread: waits indefinitely for timer handler thread to go down
The original idea of the fix is to set RUNNING state in main thread, before starting timer handler thread. But it didn't survive further cleanups: - removed "timer_thread_state" and used "thr_timer_inited" for this purpose - removed unused "timer_thread_running" - removed code responisble for "timer handler thread" shutdown synchronization, use pthread_join() instead.
That looks ok to me.
The only concern is - in end_thr_timer(), the old code had a timeout waiting for a timer thread to die. pthread_join() doesn't.
I don't know if that's a problem, perhaps not. This is one of questionable aspects of "thr timer". IMHO we either wait or not. Timeout waiting looks like hidding bugs. Anyway all client threads (=all users of this subsystem) should be down at this point.
Regards, Sergey
participants (2)
-
Sergei Golubchik -
Sergey Vojtovich