Horton

Re: heavily contended lwlocks with long wait queues scale badly

Andres Freund <andres@anarazel.de>

View thread View on postgr.es
From: Andres Freund <andres@anarazel.de>
To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Cc: pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>
Date: 2022-10-31T23:51:14Z
Lists: pgsql-hackers

Attachments

Hi,

On 2022-10-31 16:21:06 +0530, Bharath Rupireddy wrote:
> BTW, I've seen a sporadic crash (SEGV) with the patch in bg writer
> with the same set up [1], I'm not sure if it's really because of the
> patch. I'm unable to reproduce it now and unfortunately I didn't
> capture further details when it occurred.

That's likely because the prototype patch I submitted in this thread missed
updating LWLockUpdateVar().

Updated patch attached.

Greetings,

Andres Freund

Commits

  1. lwlock: Fix quadratic behavior with very long wait lists