On-demand host checks and performance issues..

[Ethan Galstad]

The host check logic in Nagios 2.x and earlier is not optimal.  I 
rewrote the entire host check logic for Nagios 3 and I've seen a 
significant improvement in performance in my testing.

- Scheduled host checks are now run in parallel
- On-demand host checks can now be skipped if the cached host check 
logic kicks in

You can see what's new in Nagios 3 by looking at the latest CVS docs:

http://nagios.cvs.sourceforge.net/*checkout*/nagios/nagios/html/docs/whatsnew.html


Thomas Guyot-Sionnest wrote:
> Hi list,
> 
> While building a Nagios server I noted that as soon as I have a few hosts
> going down, Nagios starts lagging behind and missing some checks. Even with
> the check timeout set to 1 second I still get some problems. My current
> workaround is to disable active checks on hosts that are down and this could
> be done automatically with a service check and event handler.
> 
> Part of the problem seems to be caused by the fact that Nagios check the
> host on every service failure (and recovery?). I think it wouldn't be hard
> to add a max_check_frequency parameter for hosts so that they wouldn't be
> check more often than a defined interval.
> 
> What do you think about this idea? It could solve most performance problems
> related with on-demand host checks. Is there any change I could see this at
> least for Nagios 3.0 (AFAIK parallelizing is only done on scheduled hosts
> checks in 3.0)... Even better would be using multiple threads for  reaping
> service check but I have no idea if that's technically possible and/or how
> hard it would be...
> 
> Thanks,
> 
> Thomas
> 



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

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