Re: wake up logical workers after ALTER SUBSCRIPTION

From: Nathan Bossart <nathandbossart(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Melih Mutlu <m(dot)melihmutlu(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: wake up logical workers after ALTER SUBSCRIPTION
Date: 2022-12-14 00:01:45
Message-ID: 20221214000145.GA638663@nathanxps13
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On Tue, Dec 13, 2022 at 06:32:08PM -0500, Tom Lane wrote:
> Before, there was up to 1 second (with multiple "SELECT count(1) = 0"
> probes from the test script) between the ALTER SUBSCRIPTION command
> and the "apply worker will restart" log entry. That wait is pretty
> well zapped, but instead now we're waiting hundreds of ms for the
> "apply worker has started" message.
> I've not chased it further than that, but I venture that the apply
> launcher also needs a kick in the pants, and/or there needs to be
> an interlock to ensure that it doesn't wake until after the old
> apply worker quits.

This is probably because the tests set wal_retrieve_retry_interval to
500ms. Lowering that to 1ms in seems to wipe out this
particular wait, and the total src/test/subscription test time drops from
119 seconds to 95 seconds on my machine. This probably lowers the amount
of test coverage we get on the wal_retrieve_retry_interval code paths, but
if that's a concern, perhaps we should write a test specifically for

Nathan Bossart
Amazon Web Services:

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Ian Lawrence Barwick 2022-12-14 00:09:51 Re: Proposal for internal Numeric to Uint64 conversion function.
Previous Message Paul Ramsey 2022-12-13 23:51:11 Re: [PATCH] random_normal function