From: prabakaran thirumalai
Date: July 17 2012 11:35am
Subject: bzr push into mysql-trunk branch (prabakaran.thirumalai:4068 to 4069)
 Bug#13002460
List-Archive: http://lists.mysql.com/commits/144457
X-Bug: 13002460
Message-Id: <201207171135.q6HBZRWd001296@acsmt357.oracle.com>
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 4069 prabakaran thirumalai	2012-07-17
      Bug#13002460 CRASH WHEN SHUTTING DOWN SERVER AND TOGGLING
      EVENT_SCHEDULER AT RUNTIME
      
      Analysis:
      static objects declared in Events (events.cc) is not guarded
      by mutex. This leads to race condition during shutdown.
      Client connection thread which toggles EVENT_SCHEDULER calls
      scheduler->start() or scheduler->stop() depending on the
      flag set.
      
      During shutdown, close_connections() calls Events::deinit()
      from kill_server_thread, which destroys scheduler object
      before waiting for all client connection threads to end.
      This leads to scheduler->start() or scheduler->stop() being
      called on destroyed scheduler object
      
      Fix:
      Moved Events::deinit() call after stopping all the client
      connection threads.
      
      Additional Notes:
      No test case added because send_shutdown command of mtr
      does not call Events::deinit(). Moreover scenario described
      in the bug description cannot be synchronized using mtr
      as they are two different process(mysqlslap and mysqladmin)

    modified:
      sql/events.cc
      sql/mysqld.cc
 4068 Vasil Dimov	2012-07-17 [merge]
      Merge mysql-5.6 -> mysql-trunk

    modified:
      mysql-test/include/subquery_sj.inc
      storage/innobase/dict/dict0dict.cc
      storage/innobase/dict/dict0stats.cc
      storage/innobase/include/univ.i
=== modified file 'sql/events.cc'
--- a/sql/events.cc	2012-07-02 05:46:13 +0000
+++ b/sql/events.cc	2012-07-17 11:32:03 +0000
@@ -913,8 +913,11 @@ end:
   if (res)
   {
     delete db_repository;
+    db_repository= NULL;
     delete event_queue;
+    event_queue= NULL;
     delete scheduler;
+    scheduler= NULL;
   }
   delete thd;
   /* Remember that we don't have a THD */
@@ -1065,12 +1068,16 @@ Events::dump_internal_status()
 
 bool Events::start()
 {
-  return scheduler->start();
+  bool ret= false;
+  if (scheduler) ret= scheduler->start();
+  return ret;
 }
 
 bool Events::stop()
 {
-  return scheduler->stop();
+  bool ret= false;
+  if (scheduler) ret= scheduler->stop();
+  return ret;
 }
 
 /**

=== modified file 'sql/mysqld.cc'
--- a/sql/mysqld.cc	2012-07-17 07:52:54 +0000
+++ b/sql/mysqld.cc	2012-07-17 11:32:03 +0000
@@ -1388,8 +1388,6 @@ static void close_connections(void)
   }
   mysql_mutex_unlock(&LOCK_thread_count);
 
-  Events::deinit();
-
   sql_print_information("Shutting down slave threads");
   end_slave();
 
@@ -1424,7 +1422,13 @@ static void close_connections(void)
   mysql_mutex_unlock(&LOCK_thread_count);
 #endif // Bug in BSDI kernel
 
-  /* All threads has now been aborted */
+  /* 
+    All threads have now been aborted. Stop event scheduler thread 
+    after aborting all client connections, otherwise user may 
+    start/stop event scheduler after Events::deinit() deallocates
+    scheduler object(static member in Events class)
+  */
+  Events::deinit();
   DBUG_PRINT("quit",("Waiting for threads to die (count=%u)",
                      get_thread_count()));
   mysql_mutex_lock(&LOCK_thread_count);

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