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From Kirk <>
Subject Re: Strange 'pause' activity during testing
Date Fri, 16 Dec 2011 05:34:15 GMT

JMeter Machine
CPU is idle, network is idle, no GC during "lockup". No matter, GC will drive CPU utilization
high so the fact that CPU is idle suggest resource starvation.. i.e. all of the JMeter threads
will be found to be blocked on a socket call.. i.e. the problem is in your application and
not JMeter.

I think you need outside help as the problems you're facing go beyond a simple Q&A here.
Sorry to spam the list but I do offer tuning services and a performance tuning course. We
can talk off-line about either if your interested.

Kind regards,
Kirk Pepperdine

On Dec 15, 2011, at 9:40 PM, Robin D. Wilson wrote:

> I don't use CacheManager (since that would defeat the purpose of the test -
> which is to exercise the entire system for all assets from the pages being
> requested).
> I have logged the GCs (without removing the plugins), and it doesn't do any
> GCs at all during the 'pause' period. The GC right before the pause takes
> less than a second (.26...) and the one right after is in the same ball-park
> of duration. But during the pause, no GCs at all occur.
> CPU goes to idle on the JMeter box during the pause (as does network and
> disk I/O, and swap usage). There is a _little_ activity, but I've been
> attributing that to the Remote Desktop I'm using to get to the box, and the
> PerfMon graphs that are still collecting data. But compared to before and
> after the pause the activity level is less than 2% during the 'pause'
> period, compared to 75-80% during the 'run' period.
> I will try to get the thread dump - I'm working on some production issues
> today, so I haven't had time to setup for a thread dump today.
> --
> Robin D. Wilson
> Sr. Director of Web Development
> KingsIsle Entertainment, Inc.
> VOICE: 512-777-1861
> -----Original Message-----
> From: Philippe Mouawad [] 
> Sent: Thursday, December 15, 2011 2:23 PM
> To: JMeter Users List
> Subject: Re: Strange 'pause' activity during testing
> Do you use CacheManager ?
> You should remove any plugin and activate GC logs to check it's not GC ?
> How is CPU on JMeter stack ?
> Regards
> Philippe
> On Thu, Dec 15, 2011 at 9:09 PM, Robin D. Wilson <> wrote:
>>> Maybe then there is a problem with the scanning of the HTML to 
>>> extract the
>> embedded resources, or maybe one of the embedded resources is a tar-pit.
>> If this were the case, I would expect the first sample to show the
> problem.
>> The fact that it does 600+ iterations without a problem - and _then_ 
>> stalls seems like it rules out any problem with the returned HTML 
>> (especially since the only difference in the returned result is the 
>> username supplied by JMeter).
>>> Do all the expected embedded resources get downloaded?
>> Zero errors (even with the pauses there are no errors at all).
>>> Are there any unusually long elapsed times for embedded resources?
>> I see the 'max request duration' jump up right after the pause - but 
>> it is only 10-11 seconds (not ~35 seconds like the pause).
>>> Or large gaps between the parent sample download completion and the 
>>> start
>> of the first embedded resource?
>> Not that I can see... I'll see if I can get more detail on this.
>>> That would suggest the page took a while to parse.
>> I would assume that because this happens ~600+ iterations into the 
>> test (the first time), that if it was related to parsing the page, I 
>> would see it earlier in the test run cycle. And I wouldn't expect a 
>> parsing problem to repeat on such a consistent basis - without 
>> happening on every sample.
>> Right
>> now, if it is a parsing problem, it only happens the ~600th time it 
>> sees the same page, which seems really surprising to me (then it 
>> happens again after another ~600 iterations, etc.). Also, I would 
>> expect the parser to take up some CPU and perhaps even some I/O 
>> cycles, but the PerfMon shows idle during the pause period.
>>> You'll need to select the optiion to "save subresults" in order to 
>>> see the
>> embedded samples.
>> ...
>>> BTW, you wrote you were running JMeter 2.4.1 - that does not exist, 
>>> so
>> perhaps you meant the current version, 2.5.1?
>> Sorry, I meant 2.4.  I didn't upgrade to 2.5 (and beyond) because of a 
>> previously reported problem where 2.5+ slows down my throughput to 
>> about 60% of what I get on 2.4.
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> --
> Cordialement.
> Philippe Mouawad.
> ---------------------------------------------------------------------
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