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MapReduce, mail # user - MapReduce jobs hanging or failing near completion


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Re: MapReduce jobs hanging or failing near completion
Marcos Ortiz 2011-07-08, 01:36


El 7/7/2011 8:43 PM, Kai Ju Liu escribi�:
> Over the past week or two, I've run into an issue where MapReduce jobs
> hang or fail near completion. The percent completion of both map and
> reduce tasks is often reported as 100%, but the actual number of
> completed tasks is less than the total number. It appears that either
> tasks backtrack and need to be restarted or the last few reduce tasks
> hang interminably on the copy step.
>
> In certain cases, the jobs actually complete. In other cases, I can't
> wait long enough and have to kill the job manually.
>
> My Hadoop cluster is hosted in EC2 on instances of type c1.xlarge with 4
> attached EBS volumes. The instances run Ubuntu 10.04.1 with the
> 2.6.32-309-ec2 kernel, and I'm currently using Cloudera's CDH3u0
> distribution. Has anyone experienced similar behavior in their clusters,
> and if so, had any luck resolving it? Thanks!
>
Can you post here your NN and DN logs files?
Regards

> Kai Ju

--
Marcos Lu�s Ort�z Valmaseda
  Software Engineer (UCI)
  Linux User # 418229
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