[
https://issues.apache.org/jira/browse/MAPREDUCE-969?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Todd Lipcon resolved MAPREDUCE-969.
-----------------------------------
Resolution: Duplicate
The second patch from HADOOP-4744 did indeed fix this issue. Thanks.
> NullPointerException during reduce freezes job
> ----------------------------------------------
>
> Key: MAPREDUCE-969
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-969
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: jobtracker, task, tasktracker
> Affects Versions: 0.20.2
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: bad_job_events, bad_job_jt_logs, reduce_task_logs
>
>
> We experienced several jobs stuck in Reduce on a cluster. All of the stuck
> reduce tasks had a similar were stuck at "Need another 2 map output(s) where
> 0 is already in progress" despite all of the mappers having completed, and 0
> scheduled. The stuck reducers had experienced the following exception early
> in the shuffle:
> java.lang.NullPointerException
> at
> java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2747)
> at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2670)
> Will attach more information and logs momentarily.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
