[op5-users] Réf. : Re: Réf. : Re: Réf. : Re: Nagios start time delay with Merlin

Wed Aug 26 14:45:29 CEST 2009

op5-users-bounces at lists.op5.com wrote on 26/08/2009 14:07:07:

> nicolas.raspail at bnpparibas.com wrote:
> > 
> > I will try the new beta. Is a tar file available or this version must 
be 
> > retreive from the git repository ?
> > 
> 
> You'll need to get it from git, I think. We still haven't gotten around
> to providing tar-balls automagically every time we tag. That should
> happen in the next few days though, as we're in release-frenzy at the
> moment and usually face a slightly calmer period the first week or so
> after a major release.
> 

I have got it from 
http://git.op5.org/git/?p=nagios/merlin.git;a=commitdiff;h=4ae5c2ba5bb494d60a865df8a34ec66f9f32676e

> >>>         * nagios has been restarted at timestamp 1251281934 and 
since 
> >>> that, no check have been made until timestamp 1251282809 ! 15 mins 
of 
> >>> update, that is a lot of time.
> >> And far, far more than we're experiencing here. Merlin is designed in
> >> such a way that it rather drops messages than interferes with the
> >> running Nagios daemon, so what you're seeing is almost certainly not
> >> a result of Merlin doing something weird.
> >>
> >> This should be alleviated by upgrading to the latest Merlin version
> >> though, since it ignores all events Nagios throws at it until Nagios
> >> has entered the main event execution loop. Under such circumstances,
> >> the startup time can't be affected at all by Merlin.
> >>
> > 
> > Ok, but without Merlin, my Nagios starts immediately some checks. With 

> > NDO,
> > there is also a delay (7/8 mins), and the mysql server is very busy 
during
> > this period. Maybe there is a problem else, but I can't find where.
> > 
> 
> With the latest Merlin, checks should start immediately with merlin too.
> 

I will compile it and git it a try

> > 
> >>> Also, During these tests, I have see my check and hosts latencies 
grow 
> > up 
> >>> and now, with Merlin enabled, I have a large number of orphaned 
> > checks.
> >>> With Merlin I have the following latencies (and it is increasing as 
I 
> >>> write my email) :
> >>>
> >>> Service Check Latency:  0.00 / 1299.86 / 160.156 sec
> >>> Host Check Execution Time:      2.54 / 3.19 / 2.564 sec
> >>> Host Check Latency:     0.00 / 723.49 / 304.415 sec
> >>>
> >>> Before Merlin, i don't have the exact values, but I remember that 
the 
> >>> service latency was under 50s and the host latency under 1s
> >>>
> >> Was the latency slowly increasing before, or was it totally stable?
> >> Merlin does add a small overhead to the processing of each check
> >> result, status update and a plethora of other things. If your
> >> latency was previously increasing slowly, Merlin will make it
> >> increase faster. If it was stable before, it's possible that the
> >> (very small) overhead that Merlin adds is pushing it over the
> >> limit so that the latency starts converging on infinity.
> > 
> > Before Merlin, the latency was totally stable. I understand why Merlin 
and 
> > NDO add
> > a small overhead, but what I'm facing is a huge overhead.
> > 
> > I have disabled Merlin and enabled NDO to compare. Here is my actual 
> > latency with NDO
> > after 15/20 minutes :
> > 
> > Service Check Execution Time:   0.04 / 30.03 / 0.389 sec
> > Service Check Latency:  0.00 / 1952.96 / 300.960 sec
> > Host Check Execution Time:      2.54 / 2.69 / 2.566 sec
> > Host Check Latency:     0.00 / 17.98 / 5.105 sec
> > 
> > And the latency is still decreasing as I write my email.
> > 
> 
> Ah, I think I know what's happening now. Merlin schedules a reaper
> event once every 5 seconds, where it basically just sits and waits
> for input from the daemon. This reaper event can be dropped
> completely if no pollers or peers are configured, so I'll make
> sure to add something to that effect. This should make Merlin
> perform better than NDOUtils, since we're transferring fewer
> events and we're transferring them with a more efficient protocol.

Should I test the beta5 of Merlin or wait for the release where you
will make this change ?

Right now, with NDO, my latencies seems to be stable with theses values

Service Check Execution Time:   0.04 / 30.02 / 0.372 sec
Service Check Latency:  0.00 / 1299.86 / 46.321 sec
Host Check Execution Time:      2.54 / 2.62 / 2.563 sec
Host Check Latency:     0.00 / 3.45 / 1.179 sec

Thanks for your help

Nicolas

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