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MapReduce >> mail # user >> Re: Hadoop Map Reduce Problem - Reduce failing

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Re: Hadoop Map Reduce Problem - Reduce failing
Moving to user@.

What version of Hadoop are you running?

On Apr 10, 2013, at 6:57 PM, Farrokh Shahriari wrote:

> Hello,
> I've having a problem running my map/reduce job on my cluster. The map phase, completes successfully, but the reduce phase fails with the following error message:
> Error: java.lang.NullPointerException
> at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
> at org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2835)
> at org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2756)
> I've done a lot of searching, and I've found some solutions as to not having
> any underscores in my hosts names. I changed them all, but the problem still
> hasn't resolved.
> Does anyone have any idea what the problem can be?
> Thanks,
> Farrokh

Arun C. Murthy
Hortonworks Inc.