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

["zhihai xu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-2910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15248637#comment-15248637 ] 

zhihai xu commented on YARN-2910:
---------------------------------

linked YARN-2975 to this issue, It looks like we need both YARN-2910 and YARN-2975 to fix this issue completely.

> 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, 2.6.0, 2.5.1, 2.5.2
>            Reporter: Wilfred Spiegelenburg
>            Assignee: Wilfred Spiegelenburg
>              Labels: 2.6.1-candidate
>             Fix For: 2.7.0, 2.6.1
>
>         Attachments: FSLeafQueue_concurrent_exception.txt, YARN-2910.004.patch, YARN-2910.1.patch, YARN-2910.2.patch, YARN-2910.3.patch, YARN-2910.4.patch, YARN-2910.5.patch, YARN-2910.6.patch, YARN-2910.7.patch, YARN-2910.8.patch, YARN-2910.patch
>
>
> 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:
> {noformat}
> 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)
> {noformat}
> 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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