Replace PGISOLATIONTIMEOUT with 2 * PG_TEST_TIMEOUT_DEFAULT.

Now that the more-generic variable exists, use it.

Discussion: https://postgr.es/m/20220219024136.GA3670392@rfd.leadboat.com

src/test/isolation/README

@@ -47,10 +47,10 @@ pg_isolation_regress is a tool similar to pg_regress, but instead of using
 psql to execute a test, it uses isolationtester.  It accepts all the same
 command-line arguments as pg_regress.
 
-By default, isolationtester will wait at most 300 seconds (5 minutes)
+By default, isolationtester will wait at most 360 seconds (6 minutes)
 for any one test step to complete.  If you need to adjust this, set
-the environment variable PGISOLATIONTIMEOUT to the desired timeout
-in seconds.
+the environment variable PG_TEST_TIMEOUT_DEFAULT to half the desired
+timeout in seconds.
 
 
 Test specification
@@ -138,10 +138,11 @@ Each step may contain commands that block until further action has been taken
 deadlock).  A test that uses this ability must manually specify valid
 permutations, i.e. those that would not expect a blocked session to execute a
 command.  If a test fails to follow that rule, isolationtester will cancel it
-after PGISOLATIONTIMEOUT seconds.  If the cancel doesn't work, isolationtester
-will exit uncleanly after a total of twice PGISOLATIONTIMEOUT.  Testing
-invalid permutations should be avoided because they can make the isolation
-tests take a very long time to run, and they serve no useful testing purpose.
+after 2 * PG_TEST_TIMEOUT_DEFAULT seconds.  If the cancel doesn't work,
+isolationtester will exit uncleanly after a total of 4 *
+PG_TEST_TIMEOUT_DEFAULT.  Testing invalid permutations should be avoided
+because they can make the isolation tests take a very long time to run, and
+they serve no useful testing purpose.
 
 Note that isolationtester recognizes that a command has blocked by looking
 to see if it is shown as waiting in the pg_locks view; therefore, only

src/test/isolation/isolationtester.c

@@ -46,7 +46,7 @@ static int	nconns = 0;
 static bool any_new_notice = false;
 
 /* Maximum time to wait before giving up on a step (in usec) */
-static int64 max_step_wait = 300 * USECS_PER_SEC;
+static int64 max_step_wait = 360 * USECS_PER_SEC;
 
 
 static void check_testspec(TestSpec *testspec);
@@ -128,12 +128,12 @@ main(int argc, char **argv)
 		conninfo = "dbname = postgres";
 
 	/*
-	 * If PGISOLATIONTIMEOUT is set in the environment, adopt its value (given
-	 * in seconds) as the max time to wait for any one step to complete.
+	 * If PG_TEST_TIMEOUT_DEFAULT is set, adopt its value (given in seconds)
+	 * as half the max time to wait for any one step to complete.
 	 */
-	env_wait = getenv("PGISOLATIONTIMEOUT");
+	env_wait = getenv("PG_TEST_TIMEOUT_DEFAULT");
 	if (env_wait != NULL)
-		max_step_wait = ((int64) atoi(env_wait)) * USECS_PER_SEC;
+		max_step_wait = 2 * ((int64) atoi(env_wait)) * USECS_PER_SEC;
 
 	/* Read the test spec from stdin */
 	spec_yyparse();