Re: Read-Write optimistic lock (Re: sinvaladt.c: remove msgnumLock, use atomic operations on maxMsgNum)

From: Andres Freund <andres(at)anarazel(dot)de>
To: Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru>
Cc: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Read-Write optimistic lock (Re: sinvaladt.c: remove msgnumLock, use atomic operations on maxMsgNum)
Date: 2025-06-16 14:41:03
Message-ID: dffbdwhim5ob3cjkyppivd6ll7lncznqrjclpytsdpxqqzyl5o@pejzov3rc25t
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Hi,

On 2025-06-16 17:28:31 +0300, Yura Sokolov wrote:
> 04.06.2025 00:04, Andres Freund пишет:
> > Hi,
> >
> > On 2025-06-02 21:20:33 +0300, Yura Sokolov wrote:
> >> But still problem of spin lock contention is here.
> >
> > I still would like to see a reproducer for this.
>
> For problem in sinvaladt.c we have no synthetic reproducer. But version
> with changed maxMsgNum to atomic solved customer's issue.

TBH, I don't see a point in continuing with this thread without something that
others can test. I rather doubt that the right fix here is to just change the
lock model over, but without a repro I can't evaluate that.

Greetings,

Andres Freund

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