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Getting ConcurrentModificationException for MQ service in load testing

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  • 1.  Getting ConcurrentModificationException for MQ service in load testing

    Posted 02-28-2017 11:51 PM

    Getting the below exception in inspection view during a performance test on a MQ service.

    Any generic reason why i am seeing this? Help appreciated.

     

    ============================================================================ | Exception:  ============================================================================ | Step:        Listen on lisa.vse.mq.async.queue ---------------------------------------------------------------------------- | Message:     java.util.ConcurrentModificationException ---------------------------------------------------------------------------- | Trapped Exception: null | Trapped Message:   java.util.ConcurrentModificationException ---------------------------------------------------------------------------- STACK TRACE java.util.ConcurrentModificationException      at java.util.HashMap$HashIterator.nextNode(Unknown Source)      at java.util.HashMap$EntryIterator.next(Unknown Source)      at java.util.HashMap$EntryIterator.next(Unknown Source)      at com.itko.lisa.test.FilterBaseImpl.subFilter(FilterBaseImpl.java:155)      at com.itko.lisa.test.FilterBaseImpl.postFilter(FilterBaseImpl.java:122)      at com.itko.lisa.test.TestNode.doFilters(TestNode.java:1464)      at com.itko.lisa.test.TestNode.doPostFilters(TestNode.java:1421)      at com.itko.lisa.test.TestNode.executeNode(TestNode.java:995)      at com.itko.lisa.test.TestCase.execute(TestCase.java:1283)      at com.itko.lisa.test.TestCase.execute(TestCase.java:1198)      at com.itko.lisa.test.TestCase.executeNextNode(TestCase.java:1183)      at com.itko.lisa.test.TestCase.executeTest(TestCase.java:1127)      at com.itko.lisa.coordinator.Instance.run(Instance.java:204) ============================================================================


  • 2.  Re: Getting ConcurrentModificationException for MQ service in load testing

    Posted 02-28-2017 11:51 PM
    ============================================================================ | Exception:  ============================================================================ | Step:        Listen on lisa.vse.mq.async.queue ---------------------------------------------------------------------------- | Message:     java.util.ConcurrentModificationException ---------------------------------------------------------------------------- | Trapped Exception: null | Trapped Message:   java.util.ConcurrentModificationException ---------------------------------------------------------------------------- STACK TRACE java.util.ConcurrentModificationException      at java.util.HashMap$HashIterator.nextNode(Unknown Source)      at java.util.HashMap$EntryIterator.next(Unknown Source)      at java.util.HashMap$EntryIterator.next(Unknown Source)      at com.itko.lisa.test.FilterBaseImpl.subFilter(FilterBaseImpl.java:155)      at com.itko.lisa.test.FilterBaseImpl.postFilter(FilterBaseImpl.java:122)      at com.itko.lisa.test.TestNode.doFilters(TestNode.java:1464)      at com.itko.lisa.test.TestNode.doPostFilters(TestNode.java:1421)      at com.itko.lisa.test.TestNode.executeNode(TestNode.java:995)      at com.itko.lisa.test.TestCase.execute(TestCase.java:1283)      at com.itko.lisa.test.TestCase.execute(TestCase.java:1198)      at com.itko.lisa.test.TestCase.executeNextNode(TestCase.java:1183)      at com.itko.lisa.test.TestCase.executeTest(TestCase.java:1127)      at com.itko.lisa.coordinator.Instance.run(Instance.java:204) ============================================================================


  • 3.  Re: Getting ConcurrentModificationException for MQ service in load testing

    Broadcom Employee
    Posted 03-01-2017 03:54 AM

    Hi,

     

    what version of DevTest are you using?

    There is already fix for this issue and we can provide a patch if needed.

     

    You should be also able to work around this issue by setting to run your service with 0% think time.

     

    Let us know if you need more help on this.

     

    Jan



  • 4.  Re: Getting ConcurrentModificationException for MQ service in load testing

    Posted 06-12-2017 11:00 PM

    Hi Havja02,

    Sorry, I am replying after long time.

    I would be more than help to give my scenario here.

     

    I have 4-5 MQ  virtual services where all requests use same request queue say ABC and each service has multiple operations like A1, A2, B1, B2 and C2 and C2. ( A, B and C are services and 1, 2 and 3 represent the operations).

    Each operations have thier own response queue to put the response.

    I am seeing this concurrent exception only for one service with 3 operations. This comes up only few times..may be for every 500 hits I see it once. I have 200 ms for each of the responses in the image.

     

    As you mentioned, I am going to try with 0 think scale, however, Performance test team wants responses not less than 200ms.

     

    Please guide on the patch and the path to put the patch.

     

    thanks

    Vinay



  • 5.  Re: Getting ConcurrentModificationException for MQ service in load testing
    Best Answer

    Posted 06-12-2017 11:31 PM

    Are we still talking about the ConcurrentModificationException?  I had sent a different user with your name instructions for getting the patch back in November.  Was that you?  Did you contact support, give them your exact DevTest version, and get the patch for internal case number DE203338? 

     

    > I have 4-5 MQ  virtual services where all requests use same request queue

    First, how does that work?  How are you making sure each VS receives the requests meant for it if they are all listening on the same request queue?  I'm not saying it can't work, but it usually requires the use of some pretty advanced features.

     

    > I am seeing this concurrent exception only for one service with 3 operations. This comes up only few times..may be for every 500 hits I see it once. I have 200 ms for each of the responses in the image.

     

    Do all of your service images have think time in their responses, or is it just that one service with three operations?

     

    It's a race condition inside the VS, where the thread set up to send delayed responses modifies something at the same time the main VS execution thread access it.  It's going to be intermittent and very dependent on timing. The DE203338 patch should fix this.  This fix was also included in DevTest 10.0.