Re: Replace known_assigned_xids_lck by memory barrier

From: Nathan Bossart <nathandbossart(at)gmail(dot)com>
To: Michail Nikolaev <michail(dot)nikolaev(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: Replace known_assigned_xids_lck by memory barrier
Date: 2023-08-16 20:07:15
Message-ID: 20230816200715.GB2908487@nathanxps13
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On Wed, Aug 16, 2023 at 09:29:10PM +0200, Michail Nikolaev wrote:
> As answer: probably we need to change
> "If we know that we're holding ProcArrayLock exclusively, we don't
> need the read barrier."
> to
> "If we're removing xid, we don't need the read barrier because only
> the startup process can remove and add xids to KnownAssignedXids"

Ah, that explains it. v5 of the patch is attached.

Nathan Bossart
Amazon Web Services:

Attachment Content-Type Size
v5-0001-Replace-known_assigned_xids_lck-with-memory-barri.patch text/x-diff 5.9 KB

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