[jira] [Created] (YARN-2910) FSLeafQueue can throw ConcurrentModificationException

["Wilfred Spiegelenburg (JIRA)" <ji...@apache.org>]

Wilfred Spiegelenburg created YARN-2910:
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             Summary: FSLeafQueue can throw ConcurrentModificationException
                 Key: YARN-2910
                 URL: https://issues.apache.org/jira/browse/YARN-2910
             Project: Hadoop YARN
          Issue Type: Bug
          Components: fairscheduler
    Affects Versions: 2.5.0
            Reporter: Wilfred Spiegelenburg




The list that maintains the runnable and the non runnable apps are a standard ArrayList but there is no guarantee that it will only be manipulated by one thread in the system. This can lead to the following exception:

2014-11-12 02:29:01,169 ERROR [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: ERROR IN CONTACTING RM.
java.util.ConcurrentModificationException: java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:859)
at java.util.ArrayList$Itr.next(ArrayList.java:831)
at org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSLeafQueue.getResourceUsage(FSLeafQueue.java:147)
at org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSAppAttempt.getHeadroom(FSAppAttempt.java:180)
at org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler.allocate(FairScheduler.java:923)
at org.apache.hadoop.yarn.server.resourcemanager.ApplicationMasterService.allocate(ApplicationMasterService.java:516)

Full stack trace in the attached file.

We should guard against that by using a thread safe version from java.util.concurrent.CopyOnWriteArrayList




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