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From: Andres Freund <[email protected]>
Subject: [PATCH v2 2/4] tests: Add note if BackgroundPsql::wait_connect() fails
Date: Fri, 7 Mar 2025 09:44:00 -0500

If wait_connect() failed due to psql exiting, all that we'd see is a "process
ended prematurely" error thrown by IPC::Run, without ever seeing psql's error
message.

Address that by wrapping the pump() call in eval and taking note of stdout &
stderr in case of failure.

We might want to do that in pump_until() as well, but that seems to require
API changes, so let's do the easily achievable bit first.

Reviewed-by: Heikki Linnakangas <[email protected]>
Discussion: https://postgr.es/m/ggflhkciwdyotpoie323chu2c2idpjk5qimrn462encwx2io7s@thmcxl7i6dpw
---
 .../perl/PostgreSQL/Test/BackgroundPsql.pm    | 26 ++++++++++++++++---
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm b/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm
index c611a61cf4e..1deb410c133 100644
--- a/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm
+++ b/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm
@@ -154,10 +154,28 @@ sub wait_connect
 	my $banner = "background_psql: ready";
 	my $banner_match = qr/(^|\n)$banner\r?\n/;
 	$self->{stdin} .= "\\echo $banner\n\\warn $banner\n";
-	$self->{run}->pump()
-	  until ($self->{stdout} =~ /$banner_match/
-		  && $self->{stderr} =~ /$banner\r?\n/)
-	  || $self->{timeout}->is_expired;
+
+	# IPC::Run throws in case psql exits while we're pumping. To make it
+	# easier to diagnose that, catch the error, report stdout/stderr at time
+	# of death and reraise.
+	eval {
+		$self->{run}->pump()
+		  until ($self->{stdout} =~ /$banner_match/
+			  && $self->{stderr} =~ /$banner\r?\n/)
+		  || $self->{timeout}->is_expired;
+	};
+	if ($@)
+	{
+		chomp(my $stdout = $self->{stdout});
+		chomp(my $stderr = $self->{stderr});
+		chomp(my $err = $@);
+		diag qq(psql died while connecting:
+  stdout: $stdout
+  stderr: $stderr
+  perl error: $err
+);
+		die "psql died while connecting";
+	}
 
 	note "connect output:\n",
 	  explain {
-- 
2.48.1.76.g4e746b1a31.dirty


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Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v2-0003-tests-Fix-race-condition-in-postmaster-002_connec.patch"

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