Horton

Re: MultiXact\SLRU buffers configuration

x4mmm@yandex-team.ru

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: 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 <pgsql-hackers@postgresql.org>
Date: 2020-11-13T11:49:36Z
Lists: pgsql-hackers 

> 10 нояб. 2020 г., в 23:07, Tomas Vondra <tomas.vondra@enterprisedb.com> написал(а):
> 
> On 11/10/20 7:16 AM, Andrey Borodin wrote:
>> 
>> 
>> but this picture was not stable.
>> 
> 
> Seems we haven't made much progress in reproducing the issue :-( I guess
> we'll need to know more about the machine where this happens. Is there
> anything special about the hardware/config? Are you monitoring size of
> the pg_multixact directory?

It's Ubuntu 18.04.4 LTS, Intel Xeon E5-2660 v4, 56 CPU cores with 256Gb of RAM.
PostgreSQL 10.14, compiled by gcc 7.5.0, 64-bit

No, unfortunately we do not have signals for SLRU sizes.
3.5Tb mdadm raid10 over 28 SSD drives, 82% full.

First incident triggering investigation was on 2020-04-19, at that time cluster was running on PG 10.11. But I think it was happening before.

I'd say nothing special...

> 
>> How do you collect wait events for aggregation? just insert into some table with cron?
>> 
> 
> No, I have a simple shell script (attached) sampling data from
> pg_stat_activity regularly. Then I load it into a table and aggregate to
> get a summary.

Thanks!

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.