MySQL PBM

system · May 10, 2005, 4:06pm

Hello,

I try to change a global varibale in MySQL

I conenct under root to mysql and enter :

SET GLOBAL wait_timeout = 60;

also
SET SESSION wait_timeout = 60;

but when I look at

SHOW VARIABLES;

I still have a wait_timeout set to 28800 which is the default value

I also tried to update this value through the my.cnf file but the pbm is the same.

So I’ve googled wait_timeout and I found this in the mysql website
http://bugs.mysql.com/bug.php?id=790

Description:
When MySQL is compiled from ports collection with LinuxThreads (2.2.3_12) under
FreeBSD 5.0 RELEASE, wait_timeout parameter gets ignored. This is valid both
setting value in my.cnf or from command line (SET GLOBAL wait_timeout).

I heard that same issue is with other versions of mysql (both 4.0.x and 3.23.x
releases) as well as different versions of FreeBSD.

This bug causes persistent connections to hang for a long time.

But my box isn’t FreeBSD release

Any idea ?

Pascal

system · May 10, 2005, 4:10pm

I’ve set the interactive_timeout rather than wait_timeout and now it is ok

sorry

system · May 11, 2005, 6:26am

In fact even if the show Variables did show that the wait_timeout was set to 60, the show processlist; did show us that the value taken in account was still 28 800

In fact to take in account this value wa had to comment, in my.cnf the line

[mysqlhotcopy]

interactive-timeout

Now our cpu usage is lesser than before and same for the load average.

The thread_cache_size and wait_timeout value may really help when you have a very busy MySQL server.

Also do not forget to always have a max_connections set higher than the one set in httpd (256 by default).
By default in mysql the max_connexion is set to 100. You should change it to 300 by example

Every comments are as usual welcome

Pascal