Horton

Re: BUG: Former primary node might stuck when started as a standby

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: 'Alexander Lakhin' <exclusion@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Aleksander Alekseev <aleksander@timescale.com>
Date: 2026-03-04T06:29:35Z
Lists: pgsql-hackers 
On Wed, Mar 04, 2026 at 02:31:29PM +0900, Michael Paquier wrote:
> As a whole, it looks like we should just switch the teardown() call to
> a stop() call in the first test with xact_009_10, backpatch it, and
> call it a day.  No need for injection points and no need for GUC
> tweaks.

With a little bit more patience, I have reproduced the same failure as
Alexander using the bgwriter trick, -DWAL_DEBUG and his reproducer
script with parallel runs of the 009 recovery test.  The attached
patch is also proving to work.  The failure happens at the 2nd~3rd
iteration without the fix, and the tests are able to last more than 50
iterations with the fix.

As far as I can see by scanning the history of the test, this is a
copy-pasto coming from 30820982b295 where the tests were initially
introduced, where teardown_node() was copied across the test
sequences.  As we want to check that a promoted standby is able to
commit the 2PC transactions issued on the primary, a plain stop() will
equally work.

I'll push this fix shortly, taking care of one instability.  Nice
investigation on this one, Alexander, by the way.
--
Michael

Commits

  1. Fix rare instability in recovery TAP test 004_timeline_switch

  2. Fix rare instability in recovery TAP test 009_twophase