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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5394) JobTracker might schedule 2 attempts of the same task with the same attempt id across restarts
Date Sun, 08 Mar 2009 04:10:56 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5394?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12679949#action_12679949
] 

Devaraj Das commented on HADOOP-5394:
-------------------------------------

I suggest we move to the model of moving to the model where the restart count is based on
the number of times the JobTracker got restarted rather than associating the count with a
per job restart (as it is today). The restart-count read/update could be the first thing that
the JT ever does as soon as it starts up.

> JobTracker might schedule 2 attempts of the same task with the same attempt id across
restarts
> ----------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-5394
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5394
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>            Reporter: Amar Kamat
>            Assignee: Amar Kamat
>            Priority: Critical
>
> This can happen when the jobtracker gets restarted more than once. In such cases, the
jobtracker depends on the jobhistory file for the next restart count. If the new restart-count
is not flushed to the file then there is a fair chance that upon next restart, the jobtracker
might schedule a new attempt with an existing id. This can cause problems not only with the
side-effect files but also can cause the jobtracker to be in an inconsistent state.

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