Embedded Perl in Nagios 4

[Andreas Ericsson]

On 12/18/2012 09:29 AM, Samuel Kidman wrote:
> Hello
> 
> I just had a look at Ethan's slide decks on Nagios 4 from 2012 Nagios
> Conference, and found out that embedded perl won't be in Nagios 4.
> I'm running a distributed Nagios deployment that makes extensive use
> of perl plugins, and the performance of my Nagios servers is
> beginning to struggle a bit as a result. I was working on making my
> plugins work with embedded perl but since this is now not an option I
> was wondering what others will be doing to optimise perl plugins
> without embedded perl?
> 

For starters, you should just upgrade and it's entirely possible that
the performance issues go away completely. Nagios 4 has awesome check
scaling.

The second thing to do would be to look into running mod_gearman with
workers living on the same server as the master Nagios process.
mod_gearman still has embedded perl support (although it really only
makes a difference for "large" plugins).

The third thing to do would be to inspect your most "expensive" plugins
(expensive in terms of Perl loadtime multiplied by the number of times
the plugin is used for any given time interval) and see if rewriting
them in a different language makes a huge difference. We did that for
the snmp interface checks when one of our large customers wanted to
monitor some 60000 services. Perl simply wasn't fast enough. Embedding
it meant we couldn't fork() fast enough (embedding languages has its
own overhead too), and it still leaked memory, so we rewrote them in C
and we cut system load by more than 85%.

The fourth thing to do would be to either sponsor a developer or buy
development time to build a special-purpose Nagios worker that handles
perl checks and that has a perl interpreter and a cache embedded. It's
not certain that would be better than just running the perl interpreter
directly. Without a cache, embedded perl is completely useless, since
it still has to bytecompile all the modules, and with it it can grow
to consume all memory on the system, no matter how carefully you write
your plugins. Tradeoffs, compromises and possible leaks no matter what
you do if you start down that route. It might be awesome though, so I
guess it could be worth a shot.

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

Considering the successes of the wars on alcohol, poverty, drugs and
terror, I think we should give some serious thought to declaring war
on peace.

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