Difference in CPU time with and without ePN

[Thomas Guyot-Sionnest]

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Andreas Ericsson wrote:
> Thomas Guyot-Sionnest wrote:
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>> On 09/01/08 03:35 AM, Andreas Ericsson wrote:
>>> Have you found a way around the memory leakage? Otherwise, I still believe
>>> it's  more hassle than it's worth, and effort would be better spent to cut
>>> the number of fork()'s in half by having Nagios multiplex its checks.
>> I never noticed any memory problem with the ePN and my Nagios often ran
>> for many consecutive months without being stopped (doing SIGHUPs from
>> time to time to update the config trough)
>>
>> Could you direct me to some documents of communication archives that
>> point out the problem?
>>
> 
> http://www.google.se/search?q=%2Bnagios+%2B%22embedded+perl%22+%2B%22memory+leak%22
> 
> Embedded perl leaks memory. Alot. If you have a setup where it doesn't,
> you're pretty much unique. Look for "memory leak" or "embedded perl" in
> the nagios-devel and nagios-users archives, apart from the link above.
> 
> Which versions of Nagios and Perl are you using? What system/hw is this
> on? ld, glibc and gcc versions might also be interesting, as well as
> which options you used when compiling Nagios.
> 
> If the plugins are custom ones, that could also be worth having a look
> at. In so far as I know though, Stanley Hopcroft has been trying well
> over a year to consign the leaks into oblivion, with some but far from
> complete success, and the result varies heavily depending on a lot of
> different things, all of which aren't 100% clear to anyone.
> 

Well, yesterday I had to kill and restart Nagios to make changes to Perl
modules apply (HUP wouldn't do) and it's true that Nagios now use much
less memory, so indeed there seems to be leaks. However with 2GiB of RAM
it would take months (maybe more than a year) to fill up the server
memory. I don't graph real memory usage yet (used memory minus
cache/buffers) so I can't really tell how fast it increase, but it's for
sure not a big deal with 2GiB.

HUPs have been said to cause memory leaks as well and
1. In average I probably HUP Nagios 2-3 times a week.
2. Automated scripts probably do the same on config pulls from AD (The
HUP only happens if the config changes, but that happens quite often)

On the solutions side, you can.

1. Kill and restart Nagios instead of HUP'ing it (Why don't nagios
execve itself on HUPs BTW?)
2. Monitor the Nagios process memory usage, with optionally an event
handler for automated restarts
3. Schedule automated restarts every day/week/month or so
4. Add more memory

For me the benefits is definitely worth the downsides.

- --
Thomas
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