Problem with Concurrency Thread Group / Throughput Shaping Timer Combination

[jkret...@yahoo.com]

I set-up a JMeter test using the Concurrency Thread Group and the Schedule Feedback Function of the Concurrency Throughput Timer.  The test runs fine for about 20-25 minutes with the expected, predictable ramp-up in throughput and thread count.  However, about 20 minutes into the test the active threads start jumping around and it looks like the Concurrency Thread Group is over-correcting the thread count in both directions (see the attached image of active threads).  Soon thereafter the CTG stops adding threads and then it stops all the threads and then the test stops.  The 'Hold Target Rate Time' on the CTG is set to one hour and the test only reaches about 20% of the target RPS set in the Throughput Shaping Timer.  There are no errors in the log file.  Any ideas?

[Andrey Pokhilko]

Hi,

It all depends on how you configure all parts of the process. What are the params of schedule feedback function?

Schedule feedback function reacts on TST internal state, which in turn reacts to changes in response times.

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Andrey Pokhilko

02.06.2018 00:12, jkretsch_1 via jmeter-plugins пишет:

I set-up a JMeter test using the Concurrency Thread Group and the Schedule Feedback Function of the Concurrency Throughput Timer.  The test runs fine for about 20-25 minutes with the expected, predictable ramp-up in throughput and thread count.  However, about 20 minutes into the test the active threads start jumping around and it looks like the Concurrency Thread Group is over-correcting the thread count in both directions (see the attached image of active threads).  Soon thereafter the CTG stops adding threads and then it stops all the threads and then the test stops.  The 'Hold Target Rate Time' on the CTG is set to one hour and the test only reaches about 20% of the target RPS set in the Throughput Shaping Timer.  There are no errors in the log file.  Any ideas?

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[John Kretschmann]

The Schedule Feedback function is like so ... ${__tstFeedback(Throughput_Shaping_Timer,1,100,10) ... where Throughput_Shaping_Timer is the name of my Throughput Shaping Timer test step.  The test tops out at around 16 active threads and I've specified a max of 100 so I don't think it's running out of available threads.

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From: Andrey Pokhilko <ap...@ya.ru>
To: jmeter-...@googlegroups.com
Sent: Friday, June 1, 2018 11:53 PM
Subject: Re: [jmeter-plugins] Problem with Concurrency Thread Group / Throughput Shaping Timer Combination

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[Andrey Pokhilko]

I currently have no idea why this happens. Can you enable debug logging for "kg.apc" package and run it again, to see debug messages in jmeter.log?

Andrey Pokhilko

02.06.2018 16:47, 'John Kretschmann' via jmeter-plugins пишет:

[jkret...@yahoo.com]

Hi Andrey,

Just got back from vacation.  Can you tell me how to enable debug logging for the kg.apc package?

On Saturday, June 2, 2018 at 10:49:29 AM UTC-7, Andrey Pokhilko wrote:

I currently have no idea why this happens. Can you enable debug logging for "kg.apc" package and run it again, to see debug messages in jmeter.log?

Andrey Pokhilko

02.06.2018 16:47, 'John Kretschmann' via jmeter-plugins пишет:

The Schedule Feedback function is like so ... ${__tstFeedback(Throughput_Shaping_Timer,1,100,10) ... where Throughput_Shaping_Timer is the name of my Throughput Shaping Timer test step.  The test tops out at around 16 active threads and I've specified a max of 100 so I don't think it's running out of available threads.

---

From: Andrey Pokhilko <a...@ya.ru>

To: jmeter-...@googlegroups.com
Sent: Friday, June 1, 2018 11:53 PM
Subject: Re: [jmeter-plugins] Problem with Concurrency Thread Group / Throughput Shaping Timer Combination

Hi,

It all depends on how you configure all parts of the process. What are the params of schedule feedback function?

Schedule feedback function reacts on TST internal state, which in turn reacts to changes in response times.

--

Andrey Pokhilko

02.06.2018 00:12, jkretsch_1 via jmeter-plugins пишет:

I set-up a JMeter test using the Concurrency Thread Group and the Schedule Feedback Function of the Concurrency Throughput Timer.  The test runs fine for about 20-25 minutes with the expected, predictable ramp-up in throughput and thread count.  However, about 20 minutes into the test the active threads start jumping around and it looks like the Concurrency Thread Group is over-correcting the thread count in both directions (see the attached image of active threads).  Soon thereafter the CTG stops adding threads and then it stops all the threads and then the test stops.  The 'Hold Target Rate Time' on the CTG is set to one hour and the test only reaches about 20% of the target RPS set in the Throughput Shaping Timer.  There are no errors in the log file.  Any ideas?

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[Andrey Pokhilko]

https://www.blazemeter.com/blog/how-to-configure-jmeter-logging

Andrey Pokhilko

07.06.2018 20:38, jkretsch_1 via jmeter-plugins пишет:

[John Kretschmann]

Thanks.  I attached the log file.  I went through the log and things seem to be going along fine until line 19838.  At that point it looks like the TSTFeedback attempts to reduce the concurrency from 14 to 12.  However, as I scroll through the log from that point forward I don't see that any threads are being stopped so TSTFeedback keeps reducing the concurrency value.  This continues until the TSTFeedback value drops to 0 and then to -1 at which point the threads finally start to shutdown and the test stops.

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From: Andrey Pokhilko <ap...@ya.ru>
To: jmeter-...@googlegroups.com

Sent: Thursday, June 7, 2018 11:20 AM

Subject: Re: [jmeter-plugins] Problem with Concurrency Thread Group / Throughput Shaping Timer Combination

https://www.blazemeter.com/blog/how-to-configure-jmeter-logging

Andrey Pokhilko

07.06.2018 20:38, jkretsch_1 via jmeter-plugins пишет:

Hi Andrey,

Just got back from vacation.  Can you tell me how to enable debug logging for the kg.apc package?

On Saturday, June 2, 2018 at 10:49:29 AM UTC-7, Andrey Pokhilko wrote:

I currently have no idea why this happens. Can you enable debug logging for "kg.apc" package and run it again, to see debug messages in jmeter.log?

Andrey Pokhilko

02.06.2018 16:47, 'John Kretschmann' via jmeter-plugins пишет:

The Schedule Feedback function is like so ... ${__tstFeedback(Throughput_ Shaping_Timer,1,100,10) ... where Throughput_Shaping_Timer is the name of my Throughput Shaping Timer test step.  The test tops out at around 16 active threads and I've specified a max of 100 so I don't think it's running out of available threads.

[jkret...@yahoo.com]

It looks like the specific point of failure is indicated by this log message ...

2018-06-07 11:09:06,826 DEBUG k.a.j.t.f.TSTFeedback: Need to change Throughput_Shaping_Timer_concurrency: 12=>10 (15/15.339063/12)

For some reason TSTFeedback is attempting to reduce the concurrency from 12 to 10 despite the fact that the actual rps value of 15 is less than the target rps of 15.339.

[Andrey Pokhilko]

Hi,

Thanks for the log, it helped to understand the problem. I have released TST 2.5 with fixes around this problem. Can you update to 2.5 and see if it helps?

--

Andrey Pokhilko

07.06.2018 21:47, 'John Kretschmann' via jmeter-plugins пишет:

[John Kretschmann]

Same problem.  Log is attached.

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From: Andrey Pokhilko <ap...@ya.ru>
To: jmeter-...@googlegroups.com

Sent: Friday, June 8, 2018 3:19 AM

[Andrey Pokhilko]

Are you sure you have updated the TST plugin and did not leave old JAR version in lib/ext? I see no plugins manager used in JMeter log, which means you may have typical installation troubles...

I'm saying that because in the code I made sure that negative value will never be present (https://github.com/undera/jmeter-plugins/commit/64dae5668cf474bd4e0badf3a753be0cfccf6b44#diff-94b32a474bdc2a9734ba70c825831ab9R83). So I wonder how come you get the same result...

Andrey Pokhilko

09.06.2018 02:44, 'John Kretschmann' via jmeter-plugins пишет:

[John Kretschmann]

I double checked my lib/ext folder and I see both the plugins-manager.1.1 jar and the plugins-tst-2.5 jar (screenshot is attached).

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From: Andrey Pokhilko <ap...@ya.ru>
To: jmeter-...@googlegroups.com

Sent: Wednesday, June 20, 2018 5:06 AM