Re: BUG #15036: Un-killable queries Hanging in BgWorkerShutdown - Mailing list pgsql-bugs

From Salvador Jacinto
Subject Re: BUG #15036: Un-killable queries Hanging in BgWorkerShutdown
Date
Msg-id CAO6GgynS-ih8sC74cc2ssBufi84gF0X9tvTqKt35T7v0RUTRbg@mail.gmail.com
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In response to Re: BUG #15036: Un-killable queries Hanging in BgWorkerShutdown  (Thomas Munro <thomas.munro@enterprisedb.com>)
List pgsql-bugs
AMANHÃ BEREMOS

Em 07/02/2018 8:35 PM, "Thomas Munro" <thomas.munro@enterprisedb.com> escreveu:
On Thu, Feb 8, 2018 at 7:06 AM, David Kohn <djk447@gmail.com> wrote:
> I'm not clear on when we do a SetLatch on those message queues during a
> cancel of parallel workers, and a number of other things that could
> definitely invalidate this analysis, but I think there could be a plausible
> explanation in there somewhere.

shm_mq_detach_internal() does SetLatch(&victim->procLatch) ("victim"
being the counterparty process) after setting mq_detached.  So ideally
no one should ever be able to wait forever on a queue from which the
other end has detached, but perhaps there is some race condition style
bug lurking in here.  I'm going to do some testing and see if I can
break this...

> Thanks for the help on this, I hope this is helpful and do let me know if a
> stacktrace or anything else would be helpful on my end.

Yeah stack traces would be great, if you can.

--
Thomas Munro
http://www.enterprisedb.com

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