Re: O(n) tasks cause lengthy startups and checkpoints - Mailing list pgsql-hackers

From Nathan Bossart
Subject Re: O(n) tasks cause lengthy startups and checkpoints
Date
Msg-id 20220218164454.GA3403811@nathanxps13
Whole thread Raw
In response to Re: O(n) tasks cause lengthy startups and checkpoints  (Andres Freund <andres@anarazel.de>)
Responses Re: O(n) tasks cause lengthy startups and checkpoints
List pgsql-hackers
On Thu, Feb 17, 2022 at 03:12:47PM -0800, Andres Freund wrote:
>> > The improvements around deleting temporary files and serialized snapshots
>> > afaict don't require a dedicated process - they're only relevant during
>> > startup. We could use the approach of renaming the directory out of the way as
>> > done in this patchset but perform the cleanup in the startup process after
>> > we're up.
>> 
>> Perhaps this is a good place to start.  As I mentioned above, IME the
>> temporary file cleanup is the most common problem, so I think even getting
>> that one fixed would be a huge improvement.
> 
> Cool.

Hm.  How should this work for standbys?  I can think of the following
options:
    1. Do temporary file cleanup in the postmaster (as it does today).
    2. Pause after allowing connections to clean up temporary files.
    3. Do small amounts of temporary file cleanup whenever there is an
       opportunity during recovery.
    4. Wait until recovery completes before cleaning up temporary files.

I'm not too thrilled about any of these options.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com



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