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Make the pg_rewind regression tests more robust on slow systems. 

There were a couple of hard-coded sleeps in the tests: to wait for standby
to catch up with master, and to wait for promotion with "pg_ctl promote"
to complete. Instead of a fixed, hard-coded sleep, poll the server with a
query once a second. This isn't ideal either, and I wish we had a better
solution for real-world applications too, but this should fix the
immediate problem.

Patch by Michael Paquier, with some editing by me.
This commit is contained in:
Heikki Linnakangas 2015-04-22 14:28:37 +03:00
parent cef939c347
commit 54a16df010
1 changed files with 41 additions and 5 deletions
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46
src/bin/pg_rewind/RewindTest.pm
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@ -125,6 +125,37 @@ sub check_query
}
}
# Run a query once a second, until it returns 't' (i.e. SQL boolean true).
sub poll_query_until
{
my ($query, $connstr) = @_;
my $max_attempts = 30;
my $attempts = 0;
my ($stdout, $stderr);
while ($attempts < $max_attempts)
{
my $cmd = ['psql', '-At', '-c', "$query", '-d', "$connstr" ];
my $result = run $cmd, '>', \$stdout, '2>', \$stderr;
chomp($stdout);
if ($stdout eq "t")
{
return 1;
}
# Wait a second before retrying.
sleep 1;
$attempts++;
}
# The query result didn't change in 30 seconds. Give up. Print the stderr
# from the last attempt, hopefully that's useful for debugging.
diag $stderr;
return 0;
}
sub append_to_file
{
my($filename, $str) = @_;
@ -185,7 +216,7 @@ sub create_standby
# Base backup is taken with xlog files included
system_or_bail("pg_basebackup -D $test_standby_datadir -p $port_master -x >>$log_path 2>&1");
append_to_file("$test_standby_datadir/recovery.conf", qq(
primary_conninfo='$connstr_master'
primary_conninfo='$connstr_master application_name=rewind_standby'
standby_mode=on
recovery_target_timeline='latest'
));
@ -193,8 +224,11 @@ recovery_target_timeline='latest'
# Start standby
system_or_bail("pg_ctl -w -D $test_standby_datadir -o \"-k $tempdir_short --listen-addresses='' -p $port_standby\" start >>$log_path 2>&1");
# sleep a bit to make sure the standby has caught up.
sleep 1;
# Wait until the standby has caught up with the primary, by polling
# pg_stat_replication.
my $caughtup_query = "SELECT pg_current_xlog_location() = replay_location FROM pg_stat_replication WHERE application_name = 'rewind_standby';";
poll_query_until($caughtup_query, $connstr_master)
or die "Timed out while waiting for standby to catch up";
}
sub promote_standby
@ -203,9 +237,11 @@ sub promote_standby
# up standby
# Now promote slave and insert some new data on master, this will put
# the master out-of-sync with the standby.
# the master out-of-sync with the standby. Wait until the standby is
# out of recovery mode, and is ready to accept read-write connections.
system_or_bail("pg_ctl -w -D $test_standby_datadir promote >>$log_path 2>&1");
sleep 2;
poll_query_until("SELECT NOT pg_is_in_recovery()", $connstr_standby)
or die "Timed out while waiting for promotion of standby";
}
sub run_pg_rewind