Hundreds of passive checks in a second

[Andreas Ericsson]

Sean Dilda wrote:
> I have a plugin that I'm running for a few hundred hosts that checks
> what SGE (Sun GridEngine) thinks the status of the node is.  The thing
> is, these checks don't hit the actual nodes.  Instead they all interact
> with the main SGE master daemon.  This means that all these checks and
> quickly run up the load if they're run close enough.
> 
> In order to keep from running the load up I was thinking about setting
> up a cron job that would do a single query against the SGE master daemon
> for all the hosts (only slightly more overhead than querying about a
> single host) and running all the results to nagios as passive checks. 
> The problem is that nagios uses a named pipe for the command file, and
> the buffer on linux is only 4k.  So I can't write all those checks at
> once as it would overrun the 4k buffer.
> 
> I looked and there's an option for nagios to check the file as often as
> possible, but I read the code and found out that's a lie.  I would think
> that using select(2) (as opposed to sleep(3)) would really allow nagios
> to check as often as possible.
> 
> Does anyone have any ideas of how to work around this?  Or has anyone
> already tried replacing that sleep() call with a select call()?
> 

Not that I know of, but at first glance it seems like one of those good 
ideas that should have been thought of from the start.

Btw.. this belongs to nagios-devel.

> Thanks,
> 
> 
> Sean
> 

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Lead Developer


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