Close yet another race condition in replication slot test code

alvherre · alvherre · commit 41d27ee7b870 · 2021-07-29T17:26:25.000-04:00
Buildfarm shows that this test has a further failure mode when a checkpoint starts earlier than expected, so we detect a "checkpoint completed" line that's not the one we want. Change the config to try and prevent this. Per buildfarm Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://postgr.es/m/20210729.162038.534808353849568395.horikyota.ntt@gmail.com
diff --git a/src/test/recovery/t/019_replslot_limit.pl b/src/test/recovery/t/019_replslot_limit.pl
@@ -170,11 +170,21 @@
 		"requested WAL segment [0-9A-F]+ has already been removed"),
 	'check that required WAL segments are still available');
 
-# Advance WAL again, the slot loses the oldest segment.
+# Create one checkpoint, to improve stability of the next steps
+$node_master->safe_psql('postgres', "CHECKPOINT;");
+
+# Prevent other checkpoints from occurring while advancing WAL segments
+$node_master->safe_psql('postgres',
+	"ALTER SYSTEM SET max_wal_size='40MB'; SELECT pg_reload_conf()");
+
+# Advance WAL again. The slot loses the oldest segment by the next checkpoint
 my $logstart = get_log_size($node_master);
 advance_wal($node_master, 7);
 
-# wait until the WARNING is issued
+# Now create another checkpoint and wait until the WARNING is issued
+$node_master->safe_psql('postgres',
+	'ALTER SYSTEM RESET max_wal_size; SELECT pg_reload_conf()');
+$node_master->safe_psql('postgres', "CHECKPOINT;");
 my $invalidated = 0;
 for (my $i = 0; $i < 10000; $i++)
 {
