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https://issues.apache.org/jira/browse/MAPREDUCE-5079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13607299#comment-13607299
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Siddharth Seth commented on MAPREDUCE-5079:
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I like the approach as well. Having to explicitly change recovery to intercept
additional events when J/T/TA transitions start generating additional events
can get complicated fast.
Considering this is a reasonable change, the patch is simpler than expected -
bonus for the approach.
Haven't taken a comprehensive look at the patch, but some comments (some are
likely separate jiras).
- Handling FAILED / KILLED tasks from previous runs (Some jobs allow a
percentage of tasks to fail)
- For Successful tasks, if recovery fails for the successful attempt (committer
failure, etc) - should this be considered as a failure, and count towards the
max-attempt limit ?
- Speculator info from the previous run could be recovered as well.
> Recovery should restore task state from job history info directly
> -----------------------------------------------------------------
>
> Key: MAPREDUCE-5079
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5079
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: mr-am
> Affects Versions: 0.23.7
> Reporter: Jason Lowe
> Assignee: Jason Lowe
> Attachments: MAPREDUCE-5079.patch
>
>
> We've encountered a lot of hanging issues during MR-AM recovery because the
> state machines don't always end up in the same states after recovery. This
> is especially true when speculative execution is enabled. It should be
> straightforward to restore task and task attempt states directly from the
> TaskInfo and TaskAttemptInfo records in the job history file to avoid relying
> on the task state machines ending up in the proper states with the proper
> number of attempts.
> This should be a more robust solution that would also give us the option of
> recovering start time and log locations for tasks that were in-progress when
> the AM crashed.
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