Re: Monit Can't Stop Apache

[Martin Pala]

Apache (1.x) uses preforked-child model - the parent process is kind of 
manager. If you will kill it, child processes will be inherited by init 
process (PID=1) and will keep running. Because httpd pidfile now 
contains nonexistent parent process PID reference, monit thinks that the 
process is not running (which is true - monit watches just specified 
process, not its childs) and will skip stop script during restart.

The solution is quite easy - to make sure that there is no orphaned 
apache child process running, you can add 'pkill httpd' (or 'killall 
httpd') to start section of httpd init script before actual attempt to 
start the httpd.

Chris Lopeman wrote:
> Hi All,
>
> I am still trying to get my Monit setup just right.  In doing so I have 
> been testing it quite a bit.  Every once in a while I need to tell Monit 
> to quit.  This is because it wont restart and connect to a service.  I 
> tried starts and restarts and monitor and unmonitor, all through Monit 
> and nothing fixes the issue.  I have experienced this with a few 
> different services but have never really been able to reproduce it 
> consistently.  However, I think I have recently reproduced this with 
> apache and was wondering if anybody knew what was happening or how it 
> can be fix.  Basically all I seem to need to do is kill -9 the parent 
> httpd.  At that point monit seems unable to stop the service.  I looked 
> at the httpd script.  It does a killproc and I can't see why that would 
> not work.  If I run /etc/init.d/httpd stop, it does work.  But not monit 
> stop apache. 
>
> Please correct me if I am wrong, but I believe the following is 
> happening.  Monit does not see the process corresponding to the pid in 
> the run file.  So it does not call httpd stop.  Therefore when httpd 
> restart is called it fails.  Assuming what I have said is correct, then 
> I pose the question.  Are there other circumstances this symptom can 
> occur.  I believe so because I know I have seen the same affect without 
> doing a kill -9.  I wonder if there are other time the stop will  not be 
> called.  Maybe if the pid in the file gets out of sync with the running 
> process.  Or if there is no PID file at all.  As far as apache goes, I 
> am considering changing my monit start call to "httpd restart".
>
> Thanks ahead of time,
>
> Chris
>
>
>
>
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