Re: WALWriteLock

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Yambu <hyambu(at)gmail(dot)com>
Cc: Pgsql-admin <pgsql-admin(at)lists(dot)postgresql(dot)org>
Subject: Re: WALWriteLock
Date: 2021-07-07 19:52:27
Message-ID: CAMkU=1yCHs98qsSEPvkR5-kLY4Zi0au0cwd1-xUWM8Kzfyo9pA@mail.gmail.com
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On Tue, Jul 6, 2021 at 10:14 AM Yambu <hyambu(at)gmail(dot)com> wrote:

> Hello
>
> I'm seeing a lot of WALWriteLocks , is this a bad sign , what might cause
> this?
>

Are you having a performance problem you are trying to track down? If so,
this probably indicates the cause. If not, then it is probably not a bad
sign.

The likely cause is that multiple sessions are trying to COMMIT at the same
time, and are blocking on the slow fsync of the WAL data. One process will
block on WALSync, all the ones queued up behind it will block on WALWrite.

Cheers,

Jeff

>

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