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From "Siddharth Seth (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4705) Historyserver links expire before the history data does
Date Fri, 05 Oct 2012 00:07:47 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4705?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13469855#comment-13469855
] 

Siddharth Seth commented on MAPREDUCE-4705:
-------------------------------------------

The history server is supposed to be able to serve out older jobs by scanning through job
directories ({{HistoryFileManager.scanOldDirsForJob}}) if a job is not found in the jobListcache.
The number of directories it is aware of is controlled by "mapreduce.jobhistory.datestring.cache.size"
- which defaults to a reasonably high value.
Maybe this is broken at the moment ?, or we're trying to access specific jobs using a list
API of some kind.
                
> Historyserver links expire before the history data does
> -------------------------------------------------------
>
>                 Key: MAPREDUCE-4705
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4705
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: jobhistoryserver, mrv2
>    Affects Versions: 0.23.3
>            Reporter: Jason Lowe
>            Priority: Critical
>
> The historyserver can serve up links to jobs that become useless well before the job
history files are purged.  For example on a large, heavily used cluster we can end up rotating
through the maximum number of jobs the historyserver can track fairly quickly.  If a user
was investigating an issue with a job using a saved historyserver URL, that URL can become
useless because the historyserver has forgotten about the job even though the history files
are still sitting in HDFS.
> We can tell the historyserver to keep track of more jobs by increasing {{mapreduce.jobhistory.joblist.cache.size}},
but this has a direct impact on the responsiveness of the main historyserver page since it
serves up all the entries to the client at once.  It looks like Hadoop 1.x avoided this issue
by encoding the history file location into the URLs served up by the historyserver, so it
didn't have to track a mapping between job ID and history file location.

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