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From:Michael Widenius Date:August 29 1999 6:26pm
Subject:mysql freezing under high load, UNIX socket disappearing.
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>>>>> "David" == David Simmons <simmons@stripped> writes:

David> I'm running MySQL on a Linux 2.0.36 server (RedHat 5.2) with an
David> extremely high load (and the MySQL server has a rather high
David> load as well), and occasionally MySQL will freeze and its
David> UNIX-domain socket will be removed, preventing clients from
David> connecting.

David> Sometimes the stuck mysqld can be forcefully terminated ungracefully
David> with a "kill -9", other times a "kill -9" will not even dislodge the
David> process and the server must be rebooted.  I'm using a RPM'ed packaged
David> version of MySQL that was statically linked with glibc-2.0.7.

David> Has anyone experienced this condition before?  Could this
David> possibly be a problem related to MySQL's use of the Linux
David> threading?

Hi!

When the above happens, do you get anything in the 'hostname.err' file 
?

Which MySQL version are you using?

Any way you can simulate this with some test script (like fork_test.pl)

Could this problem be related to some kernel resources like available
memory or available file descriptors?

The Unix domain socket should only be removed by mysqld on a
shutdown.  Are you sure you don't have any process that removes the
socket file (like a cron job)?

If kill -9 doesn't work, then you have found a kernel bug;  Maybe it's 
time to upgrade your kernel...)

Note that you should normally NOT use kill -9;  You should first try a 
simple kill and only when this doesn't work try kill -9.  After a kill 
-9, you MUST check all tables with isamchk before restarting mysqld!

Regards,
Monty
Thread
mysql freezing under high load, UNIX socket disappearing.David Simmons27 Aug
  • Re: mysql freezing under high load, UNIX socket disappearing.Ed Carp27 Aug
  • mysql freezing under high load, UNIX socket disappearing.Michael Widenius29 Aug