| From: | Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com> |
|---|---|
| To: | Maxim Orlov <orlovmg(at)gmail(dot)com> |
| Cc: | Alexander Korotkov <aekorotkov(at)gmail(dot)com>, wenhui qiu <qiuwenhuifx(at)gmail(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: POC: make mxidoff 64 bits |
| Date: | 2024-09-12 12:25:53 |
| Message-ID: | CALT9ZEG4OoQk8OUBCNY8cT3GuUvcQ0NrphHZ9H8--VjwM5VWUw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, 12 Sept 2024 at 16:09, Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com> wrote:
> Hi, Maxim!
>
> Previously we accessed offsets in shared MultiXactState without locks as
> 32-bit read is always atomic. But I'm not sure it's so when offset become
> 64-bit.
> E.g. GetNewMultiXactId():
>
> nextOffset = MultiXactState->nextOffset;
> is outside lock.
>
> There might be other places we do the same as well.
>
I think the replacement of plain assignments by
pg_atomic_read_u64/pg_atomic_write_u64 would be sufficient.
(The same I think is needed for the patchset [1])
[1]
https://www.postgresql.org/message-id/flat/CAJ7c6TMvPz8q+nC=JoKniy7yxPzQYcCTnNFYmsDP-nnWsAOJ2g(at)mail(dot)gmail(dot)com
Regards,
Pavel Borisov
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