Merge lp:~tsarev/percona-server/5.1_fix_bug_878709 into lp:percona-server/5.1

[Oleg Tsarev]

Jenkins: http://jenkins.percona.com/view/Percona%20Server%205.1/job/percona-server-5.1-param/208/

Fixed sporadic test fails of main.percona_status_wait_query_cache_mutex.
Bug #878709.
Reason of bug - incorrect test synchronisation.
I removed sleep(1) from code, replace by "before_query_cache_mutex" and "after_query_cache_mutex" debug sync points.

Same for https://code.launchpad.net/~tsarev/percona-server/5.5_fix_bug_878709/+merge/83030

[Laurynas Biveinis (laurynas-biveinis)]

LGTM, thank you.

review: Approve

=== modified file 'Percona-Server/mysql-test/r/percona_status_wait_query_cache_mutex.result'
--- Percona-Server/mysql-test/r/percona_status_wait_query_cache_mutex.result	2011-11-24 02:01:05 +0000
+++ Percona-Server/mysql-test/r/percona_status_wait_query_cache_mutex.result	2011-12-02 17:54:27 +0000
@@ -1,27 +1,20 @@
-set GLOBAL query_cache_size=1355776;
+SET GLOBAL query_cache_size=1355776;
 flush query cache;
 flush query cache;
 reset query cache;
 flush status;
-DROP TABLE IF EXISTS t;
-CREATE TABLE t(id INT, number INT);
-INSERT INTO t VALUES (0,1);
-INSERT INTO t VALUES (1,2);
-INSERT INTO t VALUES (2,3);
-SELECT number from t where id > 0;
-number
-2
-3
-SET SESSION debug="+d,status_wait_query_cache_mutex_sleep";
-SELECT number from t where id > 0;
-SET SESSION debug="+d,status_wait_query_cache_mutex_sleep";
-SELECT number from t where id > 0;
-SET SESSION debug="+d,status_wait_query_cache_mutex_sleep";
-SHOW PROCESSLIST;
-Id	User	Host	db	Command	Time	State	Info
-Id	root	localhost	test	Sleep	Time		NULL
-Id	root	localhost	test	Query	Time	Waiting on query cache mutex	SELECT number from t where id > 0
-Id	root	localhost	test	Query	Time	Waiting on query cache mutex	SELECT number from t where id > 0
-Id	root	localhost	test	Query	Time	NULL	SHOW PROCESSLIST
-DROP TABLE t;
-set GLOBAL query_cache_size=0;
+SET DEBUG_SYNC='after_query_cache_mutex SIGNAL mutex_locked WAIT_FOR unlock_mutex';
+SELECT "mutex_locked_query" as action;
+SET DEBUG_SYNC='now WAIT_FOR mutex_locked';
+SET DEBUG_SYNC='before_query_cache_mutex SIGNAL try_lock_mutex';
+SELECT "try_lock_mutex_query" as action;
+SET DEBUG_SYNC='now WAIT_FOR try_lock_mutex';
+SELECT SQL_NO_CACHE state FROM INFORMATION_SCHEMA.PROCESSLIST WHERE info='SELECT "try_lock_mutex_query" as action';
+state
+Waiting on query cache mutex
+SET DEBUG_SYNC='now SIGNAL unlock_mutex';
+action
+mutex_locked_query
+action
+try_lock_mutex_query
+SET GLOBAL query_cache_size=0;

=== modified file 'Percona-Server/mysql-test/t/percona_status_wait_query_cache_mutex.test'
--- Percona-Server/mysql-test/t/percona_status_wait_query_cache_mutex.test	2011-11-24 02:01:05 +0000
+++ Percona-Server/mysql-test/t/percona_status_wait_query_cache_mutex.test	2011-12-02 17:54:27 +0000
@@ -1,37 +1,35 @@
 --source include/have_query_cache.inc
 --source include/have_debug.inc
-set GLOBAL query_cache_size=1355776;
+--source include/have_debug_sync.inc
+SET GLOBAL query_cache_size=1355776;
 --source include/percona_query_cache_with_comments_clear.inc
-
--- disable_warnings
-DROP TABLE IF EXISTS t;
--- enable_warnings
-CREATE TABLE t(id INT, number INT);
-INSERT INTO t VALUES (0,1);
-INSERT INTO t VALUES (1,2);
-INSERT INTO t VALUES (2,3);
-SELECT number from t where id > 0;
---connect (conn0,localhost,root,,)
---connect (conn1,localhost,root,,)
---connect (conn2,localhost,root,,)
-
---connection conn0
---error 0, ER_UNKNOWN_SYSTEM_VARIABLE
-SET SESSION debug="+d,status_wait_query_cache_mutex_sleep";
-SEND SELECT number from t where id > 0;
-SLEEP 1.0;
-
---connection conn1
---error 0, ER_UNKNOWN_SYSTEM_VARIABLE
-SET SESSION debug="+d,status_wait_query_cache_mutex_sleep";
-SEND SELECT number from t where id > 0;
-SLEEP 1.0;
-
---connection conn2
---error 0, ER_UNKNOWN_SYSTEM_VARIABLE
-SET SESSION debug="+d,status_wait_query_cache_mutex_sleep";
---replace_column 1 Id 6 Time
-SHOW PROCESSLIST;
-
-DROP TABLE t;
-set GLOBAL query_cache_size=0;
+--let try_lock_mutex_query=SELECT "try_lock_mutex_query" as action
+
+--connect (mutex_locked_conn, localhost, root,,)
+--connect (try_mutex_lock_conn, localhost, root,,)
+
+--connection mutex_locked_conn
+SET DEBUG_SYNC='after_query_cache_mutex SIGNAL mutex_locked WAIT_FOR unlock_mutex';
+send SELECT "mutex_locked_query" as action;
+
+--connection default
+SET DEBUG_SYNC='now WAIT_FOR mutex_locked';
+
+--connection try_mutex_lock_conn
+SET DEBUG_SYNC='before_query_cache_mutex SIGNAL try_lock_mutex';
+send_eval $try_lock_mutex_query;
+
+--connection default
+SET DEBUG_SYNC='now WAIT_FOR try_lock_mutex';
+eval SELECT SQL_NO_CACHE state FROM INFORMATION_SCHEMA.PROCESSLIST WHERE info='$try_lock_mutex_query';
+SET DEBUG_SYNC='now SIGNAL unlock_mutex';
+
+--connection mutex_locked_conn
+reap;
+--connection try_mutex_lock_conn
+reap;
+
+--connection default
+--disconnect mutex_locked_conn
+--disconnect try_mutex_lock_conn
+SET GLOBAL query_cache_size=0;

=== modified file 'Percona-Server/sql/sql_cache.cc'
--- Percona-Server/sql/sql_cache.cc	2011-11-24 16:33:30 +0000
+++ Percona-Server/sql/sql_cache.cc	2011-12-02 17:54:27 +0000
@@ -329,6 +329,7 @@
       (This could be done with almost no speed penalty)
 */
 
+#include "debug_sync.h"
 #include "mysql_priv.h"
 #ifdef HAVE_QUERY_CACHE
 #include <m_ctype.h>
@@ -616,10 +617,10 @@
   THD *thd = current_thd;
   const char* old_proc_info= thd->proc_info;
   thd_proc_info(thd,"Waiting on query cache mutex");
+  DEBUG_SYNC(thd, "before_query_cache_mutex");
   pthread_mutex_lock(&structure_guard_mutex);
-  DBUG_EXECUTE_IF("status_wait_query_cache_mutex_sleep", {
-      sleep(5);
-    });
+  DEBUG_SYNC(thd, "after_query_cache_mutex");
+  thd->proc_info = old_proc_info;
   while (1)
   {
     if (m_cache_lock_status == Query_cache::UNLOCKED)
@@ -667,7 +668,6 @@
     }
   }
   pthread_mutex_unlock(&structure_guard_mutex);
-  thd->proc_info = old_proc_info;
 
   DBUG_RETURN(interrupt);
 }