Fix the race condition in the test added by 7c99dc5.

Amit Kapila · Amit Kapila · commit 8ede692de512 · 2025-05-13T09:54:29.000+05:30
After executing ALTER SUBSCRIPTION tap_sub SET PUBLICATION, we did not wait for the new walsender process to restart. As a result, an INSERT executed immediately after the ALTER could be decoded and skipped, considering it is not part of any subscribed publication. And, the old apply worker could also confirm the LSN of such an INSERT. This could cause the replication to resume from a point after the INSERT. In such cases, we miss the expected warning about the missing publication. To fix this, ensure the walsender has restarted before continuing after ALTER SUBSCRIPTION. Reported-by: Tom Lane as per CI Author: vignesh C <vignesh21@gmail.com> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Discussion: https://postgr.es/m/1230066.1745992333@sss.pgh.pa.us
diff --git a/src/test/subscription/t/024_add_drop_pub.pl b/src/test/subscription/t/024_add_drop_pub.pl
@@ -91,10 +91,21 @@
 $node_publisher->safe_psql('postgres', "CREATE TABLE tab_3 (a int)");
 $node_subscriber->safe_psql('postgres', "CREATE TABLE tab_3 (a int)");
 
+my $oldpid = $node_publisher->safe_psql('postgres',
+	"SELECT pid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
+);
+
 # Set the subscription with a missing publication
 $node_subscriber->safe_psql('postgres',
 	"ALTER SUBSCRIPTION tap_sub SET PUBLICATION tap_pub_3");
 
+# Wait for the walsender to restart after altering the subscription
+$node_publisher->poll_query_until('postgres',
+	"SELECT pid != $oldpid FROM pg_stat_replication WHERE application_name = 'tap_sub' AND state = 'streaming';"
+  )
+  or die
+  "Timed out while waiting for apply worker to restart after altering the subscription";
+
 my $offset = -s $node_publisher->logfile;
 
 $node_publisher->safe_psql('postgres',"INSERT INTO tab_3 values(1)");
