From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrew Dunstan <andrew@dunslane.net>, michael.banck@credativ.de
cc: pgsql-hackers@lists.postgresql.org
Subject: Maybe BF "timedout" failures are the client script's fault?
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Date: Fri, 09 Jan 2026 15:41:03 -0500
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We've been assuming that all the "timedout" failures on BF member
fruitcrow were due to some wonkiness in the GNU/Hurd platform.
I got suspicious about that though after noticing that there are
a small number of such failures on other animals, eg [1][2][3].
In each case, the failure message claims it waited a good long
time, which is at variance with the actually observed runtime.
For instance [1] says "timed out after 14400 secs", but the
actual total test runtime is only 01:24:28 according to the
summary at the top of the page.

Looking into the buildfarm client, I realized that it's assuming that
"sleep($wait_time)" is sufficient to wait for $wait_time seconds.
However, the Perl docs point out that sleep() can be interrupted by a
signal.  So now I'm suspicious that many of these failures are caused
by a stray signal waking up the wait_timeout thread prematurely.
GNU/Hurd might just be more prone to that than other platforms.

I propose the attached patch to the BF client to try to make this
more robust.

			regards, tom lane

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dovenbird&dt=3D=
2025-11-14%2009%3A21%3A05
[2] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dconchuela&dt=
=3D2025-10-17%2018%3A32%3A07
[3] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dopaleye&dt=3D=
2026-01-08%2023%3A07%3A37


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Content-Description: make-bf-timeout-more-robust.patch

--- run_build.pl.orig	2025-11-25 07:47:25
+++ run_build.pl	2026-01-09 15:02:23
@@ -3415,7 +3415,13 @@ sub wait_timeout
 		$SIG{$sig} = 'DEFAULT';
 	}
 	$SIG{'TERM'} = \&silent_terminate;
-	sleep($wait_time);
+	# loop to absorb any unexpected signals without dying early
+	my $end_time = time + $wait_time;
+	while (time < $end_time)
+	{
+		my $delay = $end_time - time;
+		sleep($delay);
+	}
 	print STDERR "Run timed out, terminating.\n";
 	my $sig = $usig[0] || 'TERM';
 	kill $sig, $main_pid;

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