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From "Amar Kamat (JIRA)" <j...@apache.org>
Subject [jira] Resolved: (MAPREDUCE-178) Inconsistency in handling lost trackers upon jobtracker restart
Date Wed, 07 Oct 2009 10:29:31 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-178?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Amar Kamat resolved MAPREDUCE-178.
----------------------------------

    Resolution: Invalid

MAPREDUCE-873 invalidates this.

> Inconsistency in handling lost trackers upon jobtracker restart
> ---------------------------------------------------------------
>
>                 Key: MAPREDUCE-178
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-178
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Amar Kamat
>
> If a tasktracker is lost, the jobtracker kills all the tasks that were successful on
that tracker and re-executes it somewhere else. In-memory datastructures are all cleared up
for the lost tracker. Now if the jobtracker restarts, the new jobtracker has no clue about
the trackers that were lost and hence if the lost tracker join back, they will be accepted
and all the tasks on those tracker will join back. Following are the issues
> - If the running task on the lost tracker is killed, its cleanup attempt will be launched.
Now the new jobtracker has no idea about this attempt. Also the lost tracker can join back
and hence there are 2 attempts that are running with the same id, one which can move the tip
to success and other which moves the tip to killed state.
> - Ideally, the lost tracker should be asked to re-init which wont happen now.

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