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Karem
Asked: 2015-01-30 06:01:40 +0800 CST

MySQL suddenly 'crashed' but not stopped, mysqld_safe 100% cpu on CentOS 6

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Suddenly, today i see the website down.

Checking the cpu with "top" in command, i found the mysqld_Safe at the top using all of the cpu.

After some google i found some different solutions, i made a "reboot" that restarted everything and luckily everything came back on.

Now it's time to find out why this could happen and prevent it.

I check the mysql log and find this:

Version: '5.1.73'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  Source distribution
140914 13:06:32 [Note] /usr/libexec/mysqld: Normal shutdown

140914 13:06:32 [Note] Event Scheduler: Purging the queue. 0 events
140914 13:06:32  InnoDB: Starting shutdown...
140914 13:06:36  InnoDB: Shutdown completed; log sequence number 0 37356736
140914 13:06:36 [Note] /usr/libexec/mysqld: Shutdown complete

140914 13:06:36 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
140914 13:07:07 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
140914 13:07:08  InnoDB: Initializing buffer pool, size = 8.0M
140914 13:07:08  InnoDB: Completed initialization of buffer pool
140914 13:07:08  InnoDB: Started; log sequence number 0 37356736
140914 13:07:08 [Note] Event Scheduler: Loaded 0 events
140914 13:07:08 [Note] /usr/libexec/mysqld: ready for connections.
Version: '5.1.73'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  Source distribution
141222 00:16:48 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
141222  0:16:49  InnoDB: Initializing buffer pool, size = 8.0M
141222  0:16:49  InnoDB: Completed initialization of buffer pool
InnoDB: The log sequence number in ibdata files does not match
InnoDB: the log sequence number in the ib_logfiles!
141222  0:16:49  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
141222  0:16:53  InnoDB: Started; log sequence number 0 254950608
141222  0:16:53 [Note] Event Scheduler: Loaded 0 events
141222  0:16:53 [Note] /usr/libexec/mysqld: ready for connections.
Version: '5.1.73'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  Source distribution

And normally it look like this:

Version: '5.1.73'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  Source distribution
140913 23:44:50 [Note] /usr/libexec/mysqld: Normal shutdown

140913 23:44:50 [Note] Event Scheduler: Purging the queue. 0 events
140913 23:44:50  InnoDB: Starting shutdown...
140913 23:44:51  InnoDB: Shutdown completed; log sequence number 0 36460121
140913 23:44:51 [Note] /usr/libexec/mysqld: Shutdown complete

140913 23:44:51 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
140913 23:45:18 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
140913 23:45:18  InnoDB: Initializing buffer pool, size = 8.0M
140913 23:45:18  InnoDB: Completed initialization of buffer pool
140913 23:45:18  InnoDB: Started; log sequence number 0 36460121
140913 23:45:18 [Note] Event Scheduler: Loaded 0 events
140913 23:45:18 [Note] /usr/libexec/mysqld: ready for connections.

Which clearly says something: That it didnt shut down normally and it started a crash recovery.

Now my question is:

  1. Why is it even shutting down and starting? Why is there such "event" (as far as i understand?) - can this be disabled.

  2. How can i prevent this crash? If there is any clear answer to this problem.

centos

0 Answers