Re: IPC/MultixactCreation on the Standby server

From: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>
To: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
Cc: Álvaro Herrera <alvherre(at)kurilemu(dot)de>, pgsql-hackers(at)lists(dot)postgresql(dot)org, Ivan Bykov <i(dot)bykov(at)modernsys(dot)ru>, Kirill Reshke <reshkekirill(at)gmail(dot)com>
Subject: Re: IPC/MultixactCreation on the Standby server
Date: 2025-12-02 13:44:21
Message-ID: 6A068D1B-62AF-4673-91FD-DCD9E3303023@yandex-team.ru
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> On 1 Dec 2025, at 20:29, Andrey Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
>
> I'm looking through patchsets. I'll look in the morning with fresh eyes.

So far I have no findings.
I also tried to stress-test v14. I assumed that if regression slipped in, most probably it is inherited by 14 from higher versions.
I used slightly modified scripts from Dmitry who started this thread.

DB initialization:
create table tbl2 (id int primary key,val int);
insert into tbl2 select i, 0 from generate_series(1,100000) i;

Load with multi:
\set id random(1, 10000)
begin;
select * from tbl2 where id = :id for no key update;
savepoint s1;
update tbl2 set val = val+1 where id = :id;
commit;

Consistency test:
select sum(val) from tbl2;

Stress-test script:
while true; do pkill -9 postgres; ./pg_ctl -D testdb restart; (./pgbench --no-vacuum -M prepared -c 50 -j 4 -T 300 -P 1 postgres --file=load.sql &); sleep 5; done

To promote multixact races I tried this with patched version: added random sleep up to 50ms between GetNewMultiXactId() and RecordNewMultiXact().

So far I did not manage to corrupt database.

What else kind of loads worth exercising?

Best regards, Andrey Borodin.

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