Re: Warning about mysqld's behaviour

[Gerrit Pape <pape@smarden.org>]

On Sun, Apr 10, 2005 at 11:16:06PM -0400, Charlie Brady wrote:
> Version of mysql is 3.23.58. I haven't looked at other versions, so don't 
> know whether this is new or old brain-damage.
> 
> I have a straightforward run file:
> 
> #!/bin/sh
> exec /usr/libexec/mysqld \
>  --defaults-file=/etc/my.cnf \
>  --basedir=/usr \
>  --datadir=/var/lib/mysql \
>  --user=mysql \
>  --pid-file=/var/run/mysqld/mysqld.pid
> 
> This starts a set of four mysqld processes/threads:

> But notice that the pid file doesn't reference the parent process:
> 
> sh-2.05a# svstat .
> .: up (pid 31796) 123 seconds, normally down
> sh-2.05a# cat /var/run/mysqld/mysqld.pid ; echo
> 31798
> sh-2.05a#

> But, it's worse than that, Jim! The parent process - the one that 
> supervise is watching and "controlling" ignores INT, TERM and QUIT 
> signals.

> So we lose control of the daemon:

> Fortunately runit provides an easy solution to this problem (although we 
> are left with no option but to trust a pid file, with all the problems 
> that entails). We just create control/t and control/d files (at least), 
> containing:
> 
> #! /bin/sh
> exec kill -TERM $(cat /var/run/mysqld/mysqld.pid)

> [Gerrit, if you can verify this, you'll need to update your run script 
> list.]

I personally don't use mysql, I won't verify it.  I think instead of
updating the run script on the web page, I'll remove mysql completely
from the list.  This service daemon causes so many troubles for a
supervisor, that's not worth it imho, it even seems to change behavior
from version to version.

Thanks, Gerrit.