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https://issues.apache.org/jira/browse/HADOOP-1876?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12557618#action_12557618
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Devaraj Das commented on HADOOP-1876:
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bq. Should we broaden the scope HADOOP-2178 to re-work JobHistory to use
Writables rather than the custom format? Or is that a new jira?
This should be a new jira IMO.
> Persisting completed jobs status
> --------------------------------
>
> Key: HADOOP-1876
> URL: https://issues.apache.org/jira/browse/HADOOP-1876
> Project: Hadoop
> Issue Type: Improvement
> Components: mapred
> Environment: all
> Reporter: Alejandro Abdelnur
> Assignee: Alejandro Abdelnur
> Priority: Critical
> Fix For: 0.16.0
>
> Attachments: patch1876.txt, patch1876.txt
>
>
> Currently the JobTracker keeps information about completed jobs in memory.
> This information is flushed from the cache when it has outlived
> (#RETIRE_JOB_INTERVAL) or because the limit of completed jobs in memory has
> been reach (#MAX_COMPLETE_USER_JOBS_IN_MEMORY).
> Also, if the JobTracker is restarted (due to being recycled or due to a
> crash) information about completed jobs is lost.
> If any of the above scenarios happens before the job information is queried
> by a hadoop client (normally the job submitter or a monitoring component)
> there is no way to obtain such information.
> A way to avoid this is the JobTracker to persist in DFS the completed jobs
> information upon job completion. This would be done at the time the job is
> moved to the completed jobs queue. Then when querying the JobTracker for
> information about a completed job, if it is not found in the memory queue, a
> lookup in DFS would be done to retrieve the completed job information.
> A directory in DFS (under mapred/system) would be used to persist completed
> job information, for each completed job there would be a directory with the
> job ID, within that directory all the information about the job: status,
> jobprofile, counters and completion events.
> A configuration property will indicate for how log persisted job information
> should be kept in DFS. After such period it will be cleaned up automatically.
> This improvement would not introduce API changes.
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