Re: monitoring apache with multiple processes?

[Daniel Maher]

On 08/11/2010 10:50 PM, Josh Sharpe wrote:
> I'm not sure how to properly set up monit to watch multiple apache
> proceses.  I've looked at the examples and they all seem to point to a
> single PID file...
>
>
> check process apache
>      with pidfile"/usr/local/apache/logs/httpd.pid"
>
> It's here on my distro:
>
> $ cat /var/run/apache2.pid
>
> 32281
>
> But Apache has more than just one process:
>
> $ ps aux|grep apache
> www-data  6843  0.0  1.1 319016  2812 ?        Sl   15:46   0:00 
> /usr/sbin/apache2 -k start
> root     32281  0.0  0.0  97316   132 ?        Ss   Aug10   0:04 
> /usr/sbin/apache2 -k start
> www-data 32282  0.0  0.0  96544     4 ?        S    Aug10   0:00 
> /usr/sbin/apache2 -k start
> www-data 32298  0.0  1.0 385112  2612 ?        Sl   Aug10   0:01 
> /usr/sbin/apache2 -k start
>
>
> ...and none of those other processes have their own PID.  Is it sufficient that 
> monit is only watching one of them?  What happens if on of the other ones 
> starts chewing up CPU/memory?

The process that's running as user "root" (with corresponding pid in the 
pidfile) is the "parent" (or "master") process for the daemon.  The 
others are "children" (or "workers"), and since they come and go fairly 
often under normal usage, monitoring them is not a useful exercise.

The behaviour of the child processes is governed by the master 
configuration.  See these docs for more information :
http://httpd.apache.org/docs/2.2/mod/worker.html


--
Daniel Maher <dma PLUS monit AT witbe DOT net>
"The Internet is completely over." -- Prince