Horton

Re: inefficient loop in StandbyReleaseLockList()

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: bossartn@amazon.com, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, michael@paquier.xyz, sulamul@gmail.com, pgsql-hackers@postgresql.org
Date: 2021-11-06T18:06:12Z
Lists: pgsql-hackers

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I wrote:
> Hm.  I think it's not the only list function with O(N) behavior;
> in fact there used to be more such functions than there are now.
> But I could get behind a patch that annotates all of them.

Here's a quick hack at that.  Having done it, I'm not sure if it's
really worth the trouble or not ... thoughts?

			regards, tom lane

Commits

  1. Doc: add some notes about performance of the List functions.

  2. Avoid O(N^2) behavior in SyncPostCheckpoint().

  3. Avoid some other O(N^2) hazards in list manipulation.

  4. Avoid O(N^2) behavior when the standby process releases many locks.