Nagios 2.6 still not draining command pipe fast enough

Ethan Galstad nagios at nagios.org
Tue Feb 20 15:46:16 CET 2007


John P. Rouillard wrote:
> In message <45D9C0C6.8030204 at nagios.org>,
> Ethan Galstad writes:
> 
>> John P. Rouillard wrote:
>>> Hi all:
>>>
>>> I am trying to get my external correlation engine working with nagios
>>> 2.x <http://www.cs.umb.edu/~rouilj/#secnagios>, and I just can't get
>>> nagios to drain the command pipe fast enough. I see approx. 5% failure
>>> rate on writing to the command pipe with an EAGAIN error.
>>>
>>> I have increased:
>>>
>>>   nagios.h:#define COMMAND_BUFFER_SLOTS              20480
>>>   nagios.h:#define SERVICE_BUFFER_SLOTS             20480
>>>
>>> from the original 1024. In the increase of the settings from 10240 to
>>> 20480, I may see a slight decrease (maybe .5%), but I think I just want to
>>> see it. I don't think it's statistically viable.
>> John -  Does this problem still occur with Nagios 2.7 or the latest 2.x 
>> CVS code?  A separate command file worker thread should be reading 
>> entries from the external command file as fast as it can read them (as 
>> long as their are free buffer slots).
> 
> I don't know. 2.6 was the latest when I started this. I will build it
> later this week and report back.
> 
>> If there aren't any external commands, the thread waits 0.5 seconds 
>> before checking for new commands in the file.  If you have occasional 
>> bursts of check results, this could be too long to wait.  You could try 
>> experimenting with decreasing the 0.5 second delay.  Around line 4948 of 
>> base/utils.c, you'll find...
>>
>> /* wait a bit */
>> tv.tv_sec=0;
>> tv.tv_usec=500000;
>> select(0,NULL,NULL,NULL,&tv);
>>
>> You could try decreasing the value of tv.tv_usec to 100000 (0.1 seconds) 
>> and see if that helps at all.
> 
> Cool. Thanks. Maybe this is also a tuning parameter that could/should
> be exposed in the configuation files?

Possibly, but users are probably already suffering from config variable 
overload. :-)  If changing the value helps with your situation, I 
suppose something different would be in order though.

> 
> If I get my external correlation patch working, would you consider
> including the patch in the nagios core?
> 
> 				-- rouilj
> John Rouillard

Sounds interesting.  If you send a patch, I'll consider it for inclusion 
in Nagios 3, although I won't want patches that changes too many things 
once 3 goes into beta.



Ethan Galstad,
Nagios Developer
---
Email: nagios at nagios.org
Website: http://www.nagios.org

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