Test percona_processlist_row_stats is unstable

[Laurynas Biveinis]

On 5.6 trunk:

main.percona_processlist_row_stats w2 [ fail ]
        Test ended at 2016-08-25 13:31:44

CURRENT_TEST: main.percona_processlist_row_stats
--- /mnt/workspace/percona-server-5.6-trunk/BUILD_TYPE/debug/Host/debian-wheezy-x64/mysql-test/r/percona_processlist_row_stats.result 2016-08-25 14:45:52.771598998 +0300
+++ /mnt/workspace/percona-server-5.6-trunk/BUILD_TYPE/debug/Host/debian-wheezy-x64/build/mysql-test/var/2/log/percona_processlist_row_stats.reject 2016-08-25 16:31:44.339599001 +0300
@@ -53,6 +53,8 @@
 a
 20
 20
+Warnings:
+Warning 1639 debug sync point wait timed out
 SET DEBUG_SYNC= 'RESET';
 SET DEBUG_SYNC= 'execute_command_after_close_tables SIGNAL thread1_ready WAIT_FOR threads_dumped NO_CLEAR_EVENT';
 UPDATE t2 SET a = 15 WHERE a = 20;

mysqltest: Result content mismatch

The problem appears to be that

--connection conn1
SET DEBUG_SYNC= 'locked_table_name SIGNAL thread1_ready WAIT_FOR threads_dumped NO_CLEAR_EVENT';
...
--connection conn2
SET DEBUG_SYNC= 'execute_command_after_close_tables SIGNAL thread2_ready WAIT_FOR threads_dumped NO_CLEAR_EVENT';
...
--connection conn1
reap;
SET DEBUG_SYNC= 'RESET';
--connection conn2
reap;
SET DEBUG_SYNC= 'RESET';
...

has race where if conn1 executes DEBUG_SYNC='RESET' before conn2 wakes up on threads_dumped, then conn2 will not receive the wakeup.

[Laurynas Biveinis (laurynas-biveinis)]

     https://github.com/percona/percona-server/pull/918
     https://github.com/percona/percona-server/pull/919

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-2187