Re: IPC/MultixactCreation on the Standby server - Mailing list pgsql-hackers

From Andrey Borodin
Subject Re: IPC/MultixactCreation on the Standby server
Date
Msg-id 1A375E42-E5D3-40FF-B846-E2A2EAAE211C@yandex-team.ru
Whole thread Raw
In response to IPC/MultixactCreation on the Standby server  (Dmitry <dsy.075@yandex.ru>)
List pgsql-hackers

> On 26 Jun 2025, at 14:33, Dmitry <dsy.075@yandex.ru> wrote:
>
> On 25.06.2025 16:44, Dmitry wrote:
>> I will definitely try to reproduce the problem with your patch.
> Hi Andrey!
>
> I checked with the patch, unfortunately the problem is also reproducible.
> Client processes wake up after a second and try to get information about the members of the multixact again, in an
endlessloop. 
> At the same time, the WALs are not played, the 'startup' process also hangs on the 'LWLock/BufferContent'.

My hypothesis is that MultiXactState->nextMXact is not filled often enough from redo pathes. So if you are unlucky
enough,corner case 2 reading can deadlock with startup. 
I need to verify it further, but if so - I's an ancient bug that just happens to be few orders of magnitude more
reproducibleon 17 due to performance improvements. Still a hypothetical though. 


Best regards, Andrey Borodin.


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