Horton

Re: wake up logical workers after ALTER SUBSCRIPTION

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Melih Mutlu <m.melihmutlu@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2022-12-14T00:41:05Z
Lists: pgsql-hackers 
On Tue, Dec 13, 2022 at 07:20:14PM -0500, Tom Lane wrote:
> I certainly don't think that "wake the apply launcher every 1ms"
> is a sane configuration.  Unless I'm missing something basic about
> its responsibilities, it should seldom need to wake at all in
> normal operation.

This parameter appears to control how often the apply launcher starts new
workers.  If it starts new workers in a loop iteration, it updates its
last_start_time variable, and it won't start any more workers until another
wal_retrieve_retry_interval has elapsed.  If no new workers need to be
started, it only wakes up every 3 minutes.

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

Commits

  1. Avoid type cheats for invalid dsa_handles and dshash_table_handles.

  2. Track logrep apply workers' last start times to avoid useless waits.

  3. Check for two_phase change at end of process_syncing_tables_for_apply.

  4. Wake up a subscription's replication worker processes after DDL.