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https://issues.apache.org/jira/browse/MAPREDUCE-1372?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12799612#action_12799612
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Amareshwari Sriramadasu commented on MAPREDUCE-1372:
----------------------------------------------------
bq. This actually needs a bit more work, we'll need the JIP to call 'wait' on
itself while the hosts are being resolved and then the thread doing the
resolutions will have to signal the JIP to continue.
Node resolution through heartbeat(JT.addNewTracker) also need to wait for the
thread, right?
Earlier node resolution was done by a thread, but is removed through
HADOOP-3780 and HADOOP-3620.
> ConcurrentModificationException in JobInProgress
> ------------------------------------------------
>
> Key: MAPREDUCE-1372
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1372
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: jobtracker
> Affects Versions: 0.20.1
> Reporter: Amareshwari Sriramadasu
> Priority: Blocker
> Fix For: 0.21.0
>
> Attachments: M1372-0.patch
>
>
> We have seen the following ConcurrentModificationException in one of our
> clusters
> {noformat}
> java.io.IOException: java.util.ConcurrentModificationException
> at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
> at java.util.HashMap$KeyIterator.next(HashMap.java:828)
> at
> org.apache.hadoop.mapred.JobInProgress.findNewMapTask(JobInProgress.java:2018)
> at
> org.apache.hadoop.mapred.JobInProgress.obtainNewMapTask(JobInProgress.java:1077)
> at
> org.apache.hadoop.mapred.CapacityTaskScheduler$MapSchedulingMgr.obtainNewTask(CapacityTaskScheduler.java:796)
> at
> org.apache.hadoop.mapred.CapacityTaskScheduler$TaskSchedulingMgr.getTaskFromQueue(CapacityTaskScheduler.java:589)
> at
> org.apache.hadoop.mapred.CapacityTaskScheduler$TaskSchedulingMgr.assignTasks(CapacityTaskScheduler.java:677)
> at
> org.apache.hadoop.mapred.CapacityTaskScheduler$TaskSchedulingMgr.access$500(CapacityTaskScheduler.java:348)
> at
> org.apache.hadoop.mapred.CapacityTaskScheduler.addMapTask(CapacityTaskScheduler.java:1397)
> at
> org.apache.hadoop.mapred.CapacityTaskScheduler.assignTasks(CapacityTaskScheduler.java:1349)
> at org.apache.hadoop.mapred.JobTracker.heartbeat(JobTracker.java:2976)
> at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:508)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:959)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:955)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:396)
> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:953)
> {noformat}
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