Horton

Re: MultiXact\SLRU buffers configuration

x4mmm@yandex-team.ru

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Thom Brown <thom@linux.com>
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: 2025-07-28T17:23:24Z
Lists: pgsql-hackers 
Hi Thom!

> On 1 Nov 2024, at 00:25, Thom Brown <thom@linux.com> wrote:
> 
> 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()".

FWIW we diagnosed that problem in the recent thread "IPC/MultixactCreation on the Standby server" [0].
Proposed fix is non-trivial. I'm trying to asses how many reports we had about this problem. Did you ever observe this problem again?

Thanks!


Best regards, Andrey Borodin.

[0] https://www.postgresql.org/message-id/172e5723-d65f-4eec-b512-14beacb326ce@yandex.ru

Commits

  1. Rework new SLRU test with injection points

  2. injection_point: Add injection_points.stats

  3. injection_points: Add initialization of shmem state when loading module

  4. Add injection-point test for new multixact CV usage

  5. Use conditional variable to wait for next MultiXact offset

  6. Improve performance of subsystems on top of SLRU

  7. Adjust VACUUM hastup LP_REDIRECT comments.

  8. Test replay of regression tests, attempt II.