Wilfred Spiegelenburg created YARN-2910: -------------------------------------------
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 -- This message was sent by Atlassian JIRA (v6.3.4#6332)