Horton

Re: MultiXact\SLRU buffers configuration

Thom Brown <thom@linux.com>

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From: Thom Brown <thom@linux.com>
To: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
Cc: Michael Paquier <michael@paquier.xyz>, Alvaro Herrera <alvherre@alvh.no-ip.org>, vignesh C <vignesh21@gmail.com>, Andrew Borodin <amborodin86@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, Andres Freund <andres@anarazel.de>, Thomas Munro <thomas.munro@gmail.com>, Gilles Darold <gilles@darold.net>, Alexander Korotkov <aekorotkov@gmail.com>, Daniel Gustafsson <daniel@yesql.se>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, pgsql-hackers mailing list <pgsql-hackers@postgresql.org>
Date: 2024-10-31T19:25:11Z
Lists: pgsql-hackers 
On Thu, 31 Oct 2024, 17:33 Andrey M. Borodin, <x4mmm@yandex-team.ru> wrote:

>
>
> > On 31 Oct 2024, at 17:29, Thom Brown <thom@linux.com> wrote:
> >
> > On Thu, 31 Oct 2024 at 10:47, Andrey M. Borodin <x4mmm@yandex-team.ru>
> wrote:
> >>
> >>
> >>
> >>> On 29 Oct 2024, at 21:45, Thom Brown <thom@linux.com> wrote:
> >>>
> >>> It clearly checks for interrupts, but when I saw this issue happen, it
> >>> wasn't interruptible.
> >>
> >> Perhaps, that was different multixacts?
> >> When I was observing this pathology on Standby, it was a stream of
> different reads encountering different multis.
> >>
> >> Either way startup can cancel locking process on it's own. Or is it the
> case that cancel was not enough, did you actually need termination, not
> cancel?
> >
> > Termination didn't work on either of the processes.
>
> How did you force the process to actually terminate?
> Did you observe repeated read of the same multixact?
> Was offending process holding any locks while waiting?
>

Unfortunately I didn't gather much information when it was occuring, and
prioritised getting rid of the process blocking replay. I just attached gdb
to it, got a backtrace and then "print ProcessInterrupts()".

Thom

>