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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-5929) Cleanup JobHistory file naming to do with job recovery
Date Thu, 28 May 2009 02:58:45 GMT
Cleanup JobHistory file naming to do with job recovery
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                 Key: HADOOP-5929
                 URL: https://issues.apache.org/jira/browse/HADOOP-5929
             Project: Hadoop Core
          Issue Type: Bug
          Components: mapred
    Affects Versions: 0.19.0
            Reporter: Devaraj Das
             Fix For: 0.21.0


The JobTracker uses the job history files for doing job recovery upon startup. To handle cases
where JobTracker goes down again while the recovered job is running, there is some logic that
plays with files and it ends up having two history files for some window of time during the
life of the job - actual history file, .recover file. The idea being that upon the next restart
we should be able to the maximal number of events for the job. It led to performance problems
in the job submission / recovery (part of which got addressed in HADOOP-4372). It also looks
pretty unlikely that a running job will traverse across multiple JT restarts. Even if it did,
without the .recover file, it'd only mean that we lose some tasks that got completed in a
subsequent restart. I propose that we remove the .recover file logic and base the recovery
on only the original job history file. 

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