Re: heavily contended lwlocks with long wait queues scale badly

Andres Freund <andres@anarazel.de>

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: 2022-11-20T19:56:20Z
Lists: pgsql-hackers
Hi,

On 2022-11-09 17:03:13 -0800, Andres Freund wrote:
> On 2022-11-09 09:38:08 -0800, Andres Freund wrote:
> > I'm on a hike, without any connectivity, Thu afternoon - Sun. I think it's OK
> > to push it to HEAD if I get it done in the next few hours. Bigger issues,
> > which I do not expect, should show up before tomorrow afternoon. Smaller
> > things could wait till Sunday if necessary.
> 
> I didn't get to it in time, so I'll leave it for when I'm back.

Took a few days longer, partially because I encountered an independent issue
(see 8c954168cff) while testing.

I pushed it to HEAD now.

I still think it might be worth to backpatch in a bit, but so far the votes on
that weren't clear enough on that to feel comfortable.

Regards,

Andres



Commits

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