Re: [OpenModelThreadGroup]Spike of threads on start-up

Felix Schumacher <[email protected]> Tue, 24 Sep 2024 12:26:23 +0200
Newsgroups	gmane.comp.jakarta.jmeter.user
Message-ID	<[email protected]>
Could you try to compensate for the thread setup group by adding a 
pause(6 min) (or even seven minutes) at the start of your OMTG? I 
suspect, that the start times for the threads are calculated from the 
beginning of the test instead of after the setup groups.

Felix

Am 24.09.24 um 12:01 schrieb Liliane et Robert Bourgault du Coudray:
> Ah, this is because I have a "Setup Thread Group" using the standard 
> Thread Group and running for 5 to 6 minutes to do some initial data 
> setup on the system.
> And then the OMTG will kick in.
> I have not shown the threads of this Setup Thread Group in the graph, 
> only the OMTG sequence.
>
> Le mar. 24 sept. 2024 à 16:37, Felix Schumacher 
> <[email protected]> a écrit :
>
>     Why is the spike at 06:23 (seconds? minutes?). Could it be, that
>     something is holding back your threads and releases them all at one?
>
>     If there is a lot of time at the beginning of the test, where
>     seemingly nothing happens, I would take a few thread dumps on the
>     JMeter side and look at those.
>
>     Felix
>
>     Am 19.09.24 um 03:36 schrieb Robert Bourgault du Coudray:
>>
>>     Hi,
>>     I am seeing a spike of threads on start-up, which I think is
>>     abnormal.
>>
>>     For instance, I have set an Open Model Thread Group with
>>     following parameters:
>>
>>     / * Rampup-up time over 1 min */
>>
>>     rate(0) random_arrivals(1 min) rate(30/min)
>>
>>     /* Test  for 30 mins */
>>
>>     random_arrivals(30 min) rate(30/min)
>>
>>     With these settings, we are seeing a spike of threads up to 160
>>     on start-up before the system stabilises to a more reasonable
>>     rate afterwards (see attachment).
>>
>>     This is causing false positives on our SUT.
>>
>>     Can you please suggest any workarounds or fixes?
>>
>>     Thank you
>>
>>     *Robert Bourgault du Coudray*
>>     Senior Quality Engineer | Bankwest Technology
>>     Level 14C Bankwest Place 300 Murray Street Perth WA 6000
>>     (08) 9369 9487   |   0468 770 721
>>     [email protected]
>>     bankwest.com.au <http://www.bankwest.com.au/>
>>
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