[jira] Resolved: (MAPREDUCE-178) Inconsistency in handling lost trackers upon jobtracker restart

["Amar Kamat (JIRA)" <ji...@apache.org>]

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

Amar Kamat resolved MAPREDUCE-178.
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    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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