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https://issues.apache.org/jira/browse/MAPREDUCE-5877?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Karthik Kambatla updated MAPREDUCE-5877:
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Attachment: repro-mr-5877.patch
repro-mr-5877 helps reproduce the issue. Apply the patch, start the JT, restart
the JT and run a sample MR job.
> Inconsistency between JT/TT for tasks taking a long time to launch
> ------------------------------------------------------------------
>
> Key: MAPREDUCE-5877
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5877
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: jobtracker, tasktracker
> Affects Versions: 1.2.1
> Reporter: Karthik Kambatla
> Assignee: Karthik Kambatla
> Priority: Critical
> Attachments: repro-mr-5877.patch
>
>
> For the tasks that take too long to launch (for genuine reasons like large
> distributed caches), JT expires the task. Depending on whether job recovery
> is enabled and the JT's restart state, another attempt is launched or not
> even when the JT is not restarted. The status of the attempt changes to
> "Error launching task". Meanwhile, the TT is not informed of this task expiry
> and eventually launches the task. Also, the "new" attempt might be assigned
> to the same TT leading to more inconsistent behavior.
> To avoid this, one can bump up the mapred.tasktracker.expiry.interval, but
> leading to long TT failure discovery times.
> We should have a per-job timeout for task launches/ heartbeat and JT/TT
> should be consistent in what they say.
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