Remove obsolete replication settings within TAP tests.

tglsfdc · tglsfdc · commit 151c0c5f7277 · 2020-09-29T20:03:19.000-04:00
PostgresNode.pm set "max_wal_senders = 5" for replication testing, but this seems to be slightly too low for our current test suite. Slower buildfarm members frequently report "number of requested standby connections exceeds max_wal_senders" failures, due to old walsenders not exiting instantaneously. Usually, the test does not fail overall because of automatic walreceiver restart, but sometimes the failure becomes visible; and in any case such retries slow down the test. That value came in with commit 89ac700, but was soon obsoleted by f6d6d29, which raised the built-in default from zero to 10; so that PostgresNode.pm is actually setting it to less than the conservative built-in default. That seems pretty pointless, so let's remove the special setting and let the default prevail, in hopes of making the TAP tests more robust. Likewise, the setting "max_replication_slots = 5" is obsolete and can be removed. While here, reverse-engineer a comment about why we're choosing less-than-default values for some other settings. (Note: before v12, max_wal_senders counted against max_connections so that the latter setting also needs some fiddling with.) Back-patch to v10 where the subscription tests were added. It's likely that the older branches aren't pushing the boundaries of max_wal_senders, but I'm disinclined to spend time trying to figure out exactly when it started to be a problem. Discussion: https://postgr.es/m/723911.1601417626@sss.pgh.pa.us
diff --git a/src/test/perl/PostgresNode.pm b/src/test/perl/PostgresNode.pm
@@ -469,12 +469,11 @@ sub init
 		{
 			print $conf "wal_level = replica\n";
 		}
-		print $conf "max_wal_senders = 5\n";
-		print $conf "max_replication_slots = 5\n";
 		print $conf "max_wal_size = 128MB\n";
-		print $conf "shared_buffers = 1MB\n";
 		print $conf "wal_log_hints = on\n";
 		print $conf "hot_standby = on\n";
+		# conservative settings to ensure we can run multiple postmasters:
+		print $conf "shared_buffers = 1MB\n";
 		print $conf "max_connections = 10\n";
 	}
 	else

Original file line number	Diff line number	Diff line change
`@@ -469,12 +469,11 @@ sub init`
`469`	`469`	`{`
`470`	`470`	`print $conf "wal_level = replica\n";`
`471`	`471`	`}`
`472`		`- print $conf "max_wal_senders = 5\n";`
`473`		`- print $conf "max_replication_slots = 5\n";`
`474`	`472`	`print $conf "max_wal_size = 128MB\n";`
`475`		`- print $conf "shared_buffers = 1MB\n";`
`476`	`473`	`print $conf "wal_log_hints = on\n";`
`477`	`474`	`print $conf "hot_standby = on\n";`
	`475`	`+ # conservative settings to ensure we can run multiple postmasters:`
	`476`	`+ print $conf "shared_buffers = 1MB\n";`
`478`	`477`	`print $conf "max_connections = 10\n";`
`479`	`478`	`}`
`480`	`479`	`else`