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Commits from this thread:
2026-08-12 6828b03b06 7ff4ee83f7 cfa6884677 1cafef358c 37c4a0730f 1511993de6 d47336e5f6 Fix poll_query_until() timeout handling with an undefined query in Cluster.pm
* [PATCH] Avoid uninitialized-value error in poll_query_until timeout diagnostic
@ 2026-08-09 02:59 Bryan Green <dbryan.green@gmail.com>
0 siblings, 1 reply; 3+ messages in thread
From: Bryan Green @ 2026-08-09 02:59 UTC (permalink / raw)
To: pgsql-hackers@lists.postgresql.org
Greetings,
PostgreSQL::Test::Cluster::poll_query_until() accepts an undefined query
for connection-only checks -- several recovery TAP tests call it that way:
$node->poll_query_until('postgres', undef, '');
On timeout it builds a diag message that interpolates $query:
diag qq(poll_query_until timed out executing this query:
$query
...);
Cluster.pm runs under "use warnings FATAL => 'all'", so when $query is
undefined this does not warn, it dies with "Use of uninitialized value
$query in concatenation". The result is that a timeout in a connection
only poll fails with an uninitialized-value error instead of printing
the timeout diagnostic the code is trying to produce, hiding the actual
failure.
$ perl -e 'use warnings FATAL => "all"; my $q; my $s = qq(q: $q);'
Use of uninitialized value $q in concatenation (.) or string at -e
line 1.
The fix uses a fallback string when the query is undefined:
my $msg_query = $query // '(undef - connection attempt only)';
and interpolates $msg_query instead. Test-only, one line.
--
Bryan Green
EDB: https://www.enterprisedb.com
Attachments:
0001-Avoid-uninitialized-value-error-in-poll_query_until-.patch (text/plain, 1.5K) download
From 114ae6240b1f35c31461228cc2af748bdf8813b9 Mon Sep 17 00:00:00 2001
From: Bryan Green <dbryan.green@gmail.com>
Date: Sat, 8 Aug 2026 15:27:42 -0500
Subject: [PATCH] Avoid uninitialized-value error in poll_query_until timeout
diagnostic
PostgreSQL::Test::Cluster::poll_query_until() accepts an undefined query
for connection-only checks; several recovery TAP tests call it as
poll_query_until('postgres', undef, ''). On timeout it interpolates
$query into the diag message, and because Cluster.pm runs under
"use warnings FATAL => 'all'", interpolating the undefined value dies with
"Use of uninitialized value" instead of printing the intended diagnostic,
hiding the actual timeout.
Use a fallback string when the query is undefined.
Co-authored-by: Mark Dilger <mark.dilger@enterprisedb.com>
---
src/test/perl/PostgreSQL/Test/Cluster.pm | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/test/perl/PostgreSQL/Test/Cluster.pm b/src/test/perl/PostgreSQL/Test/Cluster.pm
index 3eae4cf628..9fec6b4e42 100644
--- a/src/test/perl/PostgreSQL/Test/Cluster.pm
+++ b/src/test/perl/PostgreSQL/Test/Cluster.pm
@@ -2808,8 +2808,9 @@ sub poll_query_until
# Give up. Print the output from the last attempt, hopefully that's useful
# for debugging.
+ my $msg_query = $query // '(undef - connection attempt only)';
diag qq(poll_query_until timed out executing this query:
-$query
+$msg_query
expecting this output:
$expected
last actual query output:
--
2.49.0
* Re: [PATCH] Avoid uninitialized-value error in poll_query_until timeout diagnostic
@ 2026-08-11 11:32 Jonathan Gonzalez V. <jonathan.abdiel@gmail.com>
parent: Bryan Green <dbryan.green@gmail.com>
0 siblings, 1 reply; 3+ messages in thread
From: Jonathan Gonzalez V. @ 2026-08-11 11:32 UTC (permalink / raw)
To: Bryan Green <dbryan.green@gmail.com>; +Cc: pgsql-hackers@lists.postgresql.org
Hello!!
Bryan Green <dbryan.green@gmail.com> writes:
> ...
> Cluster.pm runs under "use warnings FATAL => 'all'", so when $query is
> undefined this does not warn, it dies with "Use of uninitialized value
> $query in concatenation". The result is that a timeout in a connection only
> poll fails with an uninitialized-value error instead of printing the timeout
> diagnostic the code is trying to produce, hiding the actual failure.
>
> $ perl -e 'use warnings FATAL => "all"; my $q; my $s = qq(q: $q);'
> Use of uninitialized value $q in concatenation (.) or string at -e line 1.
This was a little bit tricky to reproduce, but I used the following
line:
perl -I src/test/perl -MPostgreSQL::Test::Cluster -MPostgreSQL::Test::Utils -MTest::More -e 'local $PostgreSQL::Test::Utils::timeout_default=0.1; my $n=PostgreSQL::Test::Cluster->new("poll_repro",install_path=>"$ENV{PWD}/build/tmp_install/usr/local/pgsql");ok(!$n->poll_query_until("postgres", undef, ""), "connection-only timeout"); done_testing();'
I wasn't able to reproduce this in a test, so this make sense to happen
only if there's any failure during one of the tests, but this snippet
proved the failure exists.
> The fix uses a fallback string when the query is undefined:
>
> my $msg_query = $query // '(undef - connection attempt only)';
>
> and interpolates $msg_query instead. Test-only, one line.
What about using the most common way in the code instead of using `//`
operator? Something like:
my $msg_query = '(undef - connection attempt only)' unless defined $query;
This is how is done everywhere else and is a bit more clear than the
`//` operator which looks pretty tricky even for Perl
Regards,
--
Jonathan Gonzalez V.
EDB
https://www.enterprisedb.com
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: [PATCH] Avoid uninitialized-value error in poll_query_until timeout diagnostic
@ 2026-08-12 04:26 Michael Paquier <michael@paquier.xyz>
parent: Jonathan Gonzalez V. <jonathan.abdiel@gmail.com>
0 siblings, 0 replies; 3+ messages in thread
From: Michael Paquier @ 2026-08-12 04:26 UTC (permalink / raw)
To: Jonathan Gonzalez V. <jonathan.abdiel@gmail.com>; +Cc: Bryan Green <dbryan.green@gmail.com>; pgsql-hackers@lists.postgresql.org
On Tue, Aug 11, 2026 at 01:32:51PM +0200, Jonathan Gonzalez V. wrote:
> What about using the most common way in the code instead of using `//`
> operator? Something like:
>
> my $msg_query = '(undef - connection attempt only)' unless defined $query;
>
> This is how is done everywhere else and is a bit more clear than the
> `//` operator which looks pretty tricky even for Perl
Using a defined() would be my go-to choice here. Using it in an if()
or an unless does not really matter.
Anyway, will fix one way or the other. Thanks for the report.
--
Michael
Attachments:
signature.asc (application/pgp-signature, 832B) download
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2026-08-09 02:59 [PATCH] Avoid uninitialized-value error in poll_query_until timeout diagnostic Bryan Green <dbryan.green@gmail.com>
2026-08-11 11:32 ` Jonathan Gonzalez V. <jonathan.abdiel@gmail.com>
2026-08-12 04:26 ` Michael Paquier <michael@paquier.xyz>
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