Rampant Nagios

[Andreas Ericsson]

admin at jpk236.com wrote:
> Nagios v2.03b3
> FreeBSD 5.4-RELEASE-p1
> 
> On some of the hosts I monitor I've been noticing some peculiarities.
> Nagios will spontaneously become a CPU hog -- using an upwards of 80-90%
> CPU, sometimes higher.
> 

This is probably when a host with children has gone down. Nagios will 
force a check of all hosts and services beyond and "inside" the down 
host. This eats a lot of CPU, obviously.

> I try stopping nagios using FreeBSD's rc.d script for nagios.  The
> output claims nagios has stopped, but when I run `ps auxwww` there is
> still an instance of nagios running.  I can only assume the rc.d script
> was able to remove the lock file, but was not able to stop the process.
> 

This is because one of the threads (service_result_worker_thread) sets 
its cancel state to deferred and then goes off to do some 
uninterruptable IO. It will die eventually, but not straight away 
(unless it's just reached the pthread_mutex_unlock() at the end of its 
base function).

> Has anyone else experienced this behavior?
> 

It is present in all nagios since 2.01b. If it's still running after 10 
seconds, you've got a real runaway.

>  - Justin Kulikowski
>     [ http://www.jpk236.com ]
> 
> 
> 
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-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Lead Developer


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