Horton

Re: MultiXact\SLRU buffers configuration

x4mmm@yandex-team.ru

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From: "Andrey M. Borodin" <x4mmm@yandex-team.ru>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, vignesh C <vignesh21@gmail.com>, Andrew Borodin <amborodin86@gmail.com>, i.lazarev@postgrespro.ru, Yura Sokolov <y.sokolov@postgrespro.ru>, Andres Freund <andres@anarazel.de>, Thomas Munro <thomas.munro@gmail.com>, gilles@darold.net, tomas.vondra@enterprisedb.com, tomas.vondra@2ndquadrant.com, aekorotkov@gmail.com, a.lubennikova@postgrespro.ru, daniel@yesql.se, pgsql-hackers@postgresql.org
Date: 2024-04-06T11:24:12Z
Lists: pgsql-hackers 

> On 29 Feb 2024, at 06:59, Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote:
> 
> At Sat, 3 Feb 2024 22:32:45 +0500, "Andrey M. Borodin" <x4mmm@yandex-team.ru> wrote in 
>> Here's the test draft. This test reliably reproduces sleep on CV when waiting next multixact to be filled into "members" SLRU.
> 
> By the way, I raised a question about using multiple CVs
> simultaneously [1]. That is, I suspect that the current CV
> implementation doesn't allow us to use multiple condition variables at
> the same time, because all CVs use the same PCPROC member cvWaitLink
> to accommodate different waiter sets. If this assumption is correct,
> we should resolve the issue before spreading more uses of CVs.

Alvaro, Kyotaro, what's our plan for this?
It seems to late to deal with this pg_usleep(1000L) for PG17.
I propose following course of action
1. Close this long-standing CF item
2. Start new thread with CV-sleep patch aimed at PG18
3. Create new entry in July CF

What do you think?


Best regards, Andrey Borodin.

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.