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From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David G. Johnston <david.g.johnston@gmail.com>
Cc: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: Nisha Moond <nisha.moond412@gmail.com>
Cc: Gunnar Morling <gunnar.morling@googlemail.com>
Cc: pgsql-bugs@lists.postgresql.org <pgsql-bugs@lists.postgresql.org>
Subject: Re: Unexpected behavior when setting "idle_replication_slot_timeout"
Date: Wed, 09 Jul 2025 11:21:33 +0200
Message-ID: <2dcea297694d9ab8eafd1db70d385ec0b49e3d27.camel@cybertec.at> (raw)
In-Reply-To: <OSCPR01MB14966D811DB105E49289B8298F549A@OSCPR01MB14966.jpnprd01.prod.outlook.com>
References: <CADGJaX_0+FTguWpNSpgVWYQP_7MhoO0D8=cp4XozSQgaZ40Odw@mail.gmail.com>
	<CABdArM76e8-XChodqKxEiRK3tR_Yv3cymn_AWfP4bOsLDscZAg@mail.gmail.com>
	<30e91649-06dd-453e-8658-5f4acd03a3bd@oss.nttdata.com>
	<b26f13d7-769a-4b64-8bed-cb3a833c0604@oss.nttdata.com>
	<686577f2379e4b978803e72746dcf0dd7baf3937.camel@cybertec.at>
	<e0789f10-5b48-4d6b-a32c-0f4426d254df@oss.nttdata.com>
	<CAA4eK1LOyUeCHk3hMtjT-bpqXLAnjODwcO+o7+bTnB2es-fSqw@mail.gmail.com>
	<70b183fb-f66e-40d8-b0de-be8c1052fa93@oss.nttdata.com>
	<CAKFQuwYVEgy+fiHMvSoykiEef-VF-ZV9Gxv4rynk9NNK9UMPYQ@mail.gmail.com>
	<472687.1751731008@sss.pgh.pa.us>
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	<1cea80b2ed4f355ae6a68e36f56a1410b59ea4a8.camel@cybertec.at>
	<OSCPR01MB14966D811DB105E49289B8298F549A@OSCPR01MB14966.jpnprd01.prod.outlook.com>

On Wed, 2025-07-09 at 07:24 +0000, Hayato Kuroda (Fujitsu) wrote:
> > > +# Wait a bit for the replication slots to become invalid
> > > +$node->safe_psql('postgres', "SELECT pg_sleep(2)");
> > > 
> > > Is it a good idea to add 2s to 'make check-world' for one particular test?
> > 
> > That is debatable.  I thought that adding two seconds would be worth the
> > advantage of removing the injection point that only fakes the timeout.
> > We'd get better test coverage.
> > 
> > But if the people who run the regression tests dozens of times every day
> > object to the two seconds, I won't insist on this part of the patch.
> 
> I can understand both concerns. One benefit not to use the injection point is
> that any machines can run the test. Currently some BF machines do not enable
> the injection point, thus the feature has not been verified on these env.
> However, unconditional sleep makes the test longer.
> 
> Based on that, I want to propose the hybrid approach; use injection_point_attach()
> if possible, otherwise wait few seconds. One concern is that the test code may be
> bit complex, but below codes was enough on my environment.
> 
> ```
> # Check if the 'injection_points' extension is available, as it may be
> # possible that this script is run with installcheck, where the module
> # would not be installed by default.
> if ($node->check_extension('injection_points'))
> {
> 	# Register an injection point on the node to forcibly cause a slot
> 	# invalidation due to idle_timeout
> 	$node->safe_psql('postgres', 'CREATE EXTENSION injection_points;');
> 
> 	$node->safe_psql('postgres',
> 		"SELECT injection_points_attach('slot-timeout-inval', 'error');");
> }
> else
> {
> 	# Otherwise wait a bit for the replication slots to become invalid
> 	$node->safe_psql('postgres', "SELECT pg_sleep(2)");
> }
> ```
> 
> Attached patch implements the idea, which can be applied atop v2. How do you think?

I have no objections.

I'll leave the decision to Fujii Masao or whoever wants to commit something
in this area.

Yours,
Laurenz Albe





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  Subject: Re: Unexpected behavior when setting "idle_replication_slot_timeout"
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