[ https://issues.apache.org/jira/browse/YARN-2910?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14240064#comment-14240064 ]
Ray Chiang commented on YARN-2910: ---------------------------------- RE: Unit test failure. TestRMRestart passed 10 out of 10 runs for me with the patch. Patch looks good to me. +1 (nonbinding) > 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 > 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 -- This message was sent by Atlassian JIRA (v6.3.4#6332)