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https://issues.apache.org/jira/browse/MAPREDUCE-873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12749849#action_12749849
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Hudson commented on MAPREDUCE-873:
----------------------------------

Integrated in Hadoop-Mapreduce-trunk-Commit #9 (See 
[http://hudson.zones.apache.org/hudson/job/Hadoop-Mapreduce-trunk-Commit/9/])
    . Moving the CHANGES.txt comment to Incompatible section.
. Simplify job recovery. InComplete jobs are resubmitted on jobtracker restart. 
Contributed by Sharad Agarwal.


> Simplify Job Recovery
> ---------------------
>
>                 Key: MAPREDUCE-873
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-873
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: jobtracker
>    Affects Versions: 0.20.1
>            Reporter: Devaraj Das
>            Assignee: Sharad Agarwal
>             Fix For: 0.21.0
>
>         Attachments: 873_v1.patch, 873_v2.patch, 873_v3.patch
>
>
> On a couple of occasions we have seen the JobTracker not being able to handle 
> job recovery well, and leading to cluster downtime after a restart. The 
> current design for handling job recovery is complex and prone to corner cases 
> not being handled well enough. In retrospect, it seems like the transaction 
> log based approach as was proposed on HADOOP-3245 
> (http://tinyurl.com/luh9hb), would have been a better/simpler model. However, 
> that is a big project, and it seems for the medium term, just handling job 
> re-submissions after a restart is a good tradeoff. That is, the JobTracker 
> after getting restarted, will resubmit all jobs that were running in its past 
> life. They will all start from the beginning (downside is completed tasks 
> will reexecute). In the long term, the transaction log model or some variant 
> of that should be pursued.
> Thoughts/comments welcome.

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