Re: monit unresponsive to status requests?

[Jan-Henrik Haukeland]

When monit is asked to stop a process it will wait for the process to  
stop before it continues. If the process takes a long time to stop,  
monit will hang for up to 1 poll cycle before it timeout waiting for  
the process. The only reason this is sequential is for the case that  
monit is asked to restart a process. Monit restart a process by first  
calling the program's stop-command before calling the start-command -  
so to make sure that the process is stopped before the start-command  
is called, monit waits. Starting a new process is for instance non- 
sequential and is conducted in a new thread since this is considered  
"safe".

Unfortunately, when monit wait on a process to stop, the HTTP thread  
also stops, since all this stuff is run from the http thread. You may  
call this a minor design problem and you would be right. There are  
ways to work around this in the code, e.g. using a new thread, non- 
blocking techniques, a queue or flags and stuff like that, but we  
haven't really considered this to be a major problem before, because  
monit does work and will behave functional correct, i.e. with regards  
to monitoring.

Can I ask you, what kind of program you are stopping that take so  
long to stop?

Jan-Henrik


On 14. jul. 2005, at 22.44, Randy Bias wrote:

> Folks,
>
>
>     I'm new to monit, but have a hopefully quick and easy  
> question.  I've noticed that sometimes monit occasionally becomes  
> unresponsive to status requests, giving an error as follows:
>
>     monit: cannot read status from the monit daemon
>
>     The monit process is running and has not died, but is  
> unresponsive to the status request.  Making a local connection  
> attempt to the webserver socket seems to work, although monit takes  
> forever to respond after the socket is open.
>
>     As far as I can tell this happens after monit is given any kind  
> of directive.  For example, if I tell monit to stop a service it  
> becomes unresponsive for up to 10 or 15 seconds.
>
>     Has anyone else noticed this behavior?
>
>     Environment is Fedora Core 3, 2.6.9 kernel.
>
>
>
> Thanks,
>
>
> --Randy
>
>
>
>
> Randy Bias        randy-at-netenrich-dot-com
> Director of Application Engineering & Support
>
>
>
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