Hadoop Map/Reduce
  1. Hadoop Map/Reduce
  2. MAPREDUCE-1961

[gridmix3] ConcurrentModificationException when shutting down Gridmix

        Details

        • Type: Bug Bug
        • Status: Closed
        • Priority: Major Major
        • Resolution: Fixed
        • Affects Version/s: None
        • Fix Version/s: 0.22.0
        • Component/s: contrib/gridmix
        • Labels:
          None
        • Hadoop Flags:
          Reviewed

          Description

          We observed the following exception occasionally at the end of the Gridmix run:

          Exception in thread "StatsCollectorThread" java.util.ConcurrentModificationException
          at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
          at java.util.AbstractList$Itr.next(AbstractList.java:343)
          at org.apache.hadoop.mapred.gridmix.Statistics$StatCollector.updateAndNotifyClusterStatsListeners(Statistics.java:220)
          at org.apache.hadoop.mapred.gridmix.Statistics$StatCollector.run(Statistics.java:205)

            Activity

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            Hudson added a comment -

            Integrated in Hadoop-Mapreduce-trunk-Commit #523 (See https://hudson.apache.org/hudson/job/Hadoop-Mapreduce-trunk-Commit/523/)

            Show
            Hudson added a comment - Integrated in Hadoop-Mapreduce-trunk-Commit #523 (See https://hudson.apache.org/hudson/job/Hadoop-Mapreduce-trunk-Commit/523/ )
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            Chris Douglas added a comment -

            +1

            I committed this. Thanks, Hong!

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            Chris Douglas added a comment - +1 I committed this. Thanks, Hong!
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            Hong Tang added a comment -

            test-patch output:

                 [exec] -1 overall.
     [exec]
     [exec]     +1 @author.  The patch does not contain any @author tags.
     [exec]
     [exec]     -1 tests included.  The patch doesn't appear to include any new or modified tests.
     [exec]                         Please justify why no new tests are needed for this patch.
     [exec]                         Also please list what manual steps were performed to verify this patch.
     [exec]
     [exec]     +1 javadoc.  The javadoc tool did not generate any warning messages.
     [exec]
     [exec]     +1 javac.  The applied patch does not increase the total number of javac compiler warnings.
     [exec]
     [exec]     +1 findbugs.  The patch does not introduce any new Findbugs warnings.
     [exec]
     [exec]     +1 release audit.  The applied patch does not increase the total number of release audit warnings.

            -1 tests included

            The patch fixes a concurrency bug, and is hard to write unit test to cover. The patch is tested with real benchmark runs and has shown to be effective.

            Show
            Hong Tang added a comment - test-patch output: [exec] -1 overall. [exec] [exec] +1 @author. The patch does not contain any @author tags. [exec] [exec] -1 tests included. The patch doesn't appear to include any new or modified tests. [exec] Please justify why no new tests are needed for this patch. [exec] Also please list what manual steps were performed to verify this patch. [exec] [exec] +1 javadoc. The javadoc tool did not generate any warning messages. [exec] [exec] +1 javac. The applied patch does not increase the total number of javac compiler warnings. [exec] [exec] +1 findbugs. The patch does not introduce any new Findbugs warnings. [exec] [exec] +1 release audit. The applied patch does not increase the total number of release audit warnings. -1 tests included The patch fixes a concurrency bug, and is hard to write unit test to cover. The patch is tested with real benchmark runs and has shown to be effective.
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            Ranjit Mathew added a comment -

            +1 for the patch.

            Show
            Ranjit Mathew added a comment - +1 for the patch.
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            Hong Tang added a comment -

            retry hudson

            Show
            Hong Tang added a comment - retry hudson
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            Hong Tang added a comment -

            Trivial patch that uses CopyOnWriteArrayList to avoid concurrent modification. No unit test included as it is hard to reproduce the synchronization bug through unit tests.

            Show
            Hong Tang added a comment - Trivial patch that uses CopyOnWriteArrayList to avoid concurrent modification. No unit test included as it is hard to reproduce the synchronization bug through unit tests.
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            Hong Tang added a comment -

            It seems that StatsCollectorThread is still active when we call "clusterStatlisteners.clear();" from "Statistics.shutdown()".

            A simple fix is to replace "clusterStatlisteners.clear();" with "lusterStatlisteners = new ArrayList<StatListener<ClusterStats>>()".

            While we are at it, we probably should also fix the same problem with jobStatListeners.

            Show
            Hong Tang added a comment - It seems that StatsCollectorThread is still active when we call "clusterStatlisteners.clear();" from "Statistics.shutdown()". A simple fix is to replace "clusterStatlisteners.clear();" with "lusterStatlisteners = new ArrayList<StatListener<ClusterStats>>()". While we are at it, we probably should also fix the same problem with jobStatListeners.

              People

              • Assignee:
                Hong Tang
                Reporter:
                Hong Tang
              • Votes:
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                Dates

                • Created:
                  Updated:
                  Resolved:

                  Development