Re: MultiXact\SLRU buffers configuration

x4mmm@yandex-team.ru

From: "Andrey M. Borodin" <x4mmm@yandex-team.ru>

To: Alvaro Herrera <alvherre@alvh.no-ip.org>

Cc: 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 <gilles@darold.net>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Alexander Korotkov <aekorotkov@gmail.com>, Anastasia Lubennikova <a.lubennikova@postgrespro.ru>, Daniel Gustafsson <daniel@yesql.se>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, pgsql-hackers mailing list <pgsql-hackers@postgresql.org>

Date: 2024-01-28T18:17:16Z

Lists: pgsql-hackers

Attachments

0001-Add-conditional-variable-to-wait-for-next-MultXact-o.patch (application/octet-stream) patch 0001
0002-Add-wait-type-for-injection-points.patch (application/octet-stream) patch 0002
0003-Try-to-test-multixact-CV-sleep.patch (application/octet-stream) patch 0003

> On 28 Jan 2024, at 17:49, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> 
> I'd appreciate it if you or Horiguchi-san can update his patch to remove
> use of usleep in favor of a CV in multixact, and keep this CF entry to
> cover it.

Sure! Sounds great!

> Perhaps a test to make the code reach the usleep(1000) can be written
> using injection points (49cd2b93d7db)?

I've tried to prototype something like that. But interesting point between GetNewMultiXactId() and RecordNewMultiXact() is a critical section, and we cannot have injection points in critical sections...
Also, to implement such a test we need "wait" type of injection points, see step 2 in attachment. With this type of injection points I can stop a backend amidst entering information about new MultiXact.

Best regards, Andrey Borodin.

Commits

Rework new SLRU test with injection points
- 94a3373ac5c3 18.0 landed
injection_point: Add injection_points.stats
- 2e35c67f9568 18.0 landed
injection_points: Add initialization of shmem state when loading module
- b2b023aa3706 18.0 landed
Add injection-point test for new multixact CV usage
- 768a9fd5535f 18.0 landed
Use conditional variable to wait for next MultiXact offset
- a0e0fb1ba56f 17.0 landed
Improve performance of subsystems on top of SLRU
- 53c2a97a9266 17.0 landed
Adjust VACUUM hastup LP_REDIRECT comments.
- 325bc54eed4e 16.0 cited
Test replay of regression tests, attempt II.
- f47ed79cc8a0 15.0 cited