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https://issues.apache.org/jira/browse/YARN-1210?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13775746#comment-13775746
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Jian He commented on YARN-1210:
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Here's the proposed new workflow of RMApp and RMAppAttempt recovery
- After RM restarts, on RECOVER event, RMApp moves to ACCEPTED state instead of
starting a new attempt, and only the last RMAppAttempt moves to LAUNCHED state,
other attempts still move to RECOVERED state.
- when the old AM talks to the new RM, the old AM will crash because of
Exception that Application doesn't exist in cache.
- RMAppAttempt then goes to FAILED state either on AM CONTAINER_FINISHED event
sent by NM or EXPIRED event
- RMApp will then be notified, and during AttemptFailedTransition of RMApp,
restarts a new attempt depending on the number of max-am-retry.
> During RM restart, RM should start a new attempt only when previous attempt
> exits for real
> ------------------------------------------------------------------------------------------
>
> Key: YARN-1210
> URL: https://issues.apache.org/jira/browse/YARN-1210
> Project: Hadoop YARN
> Issue Type: Sub-task
> Reporter: Vinod Kumar Vavilapalli
> Assignee: Jian He
>
> When RM recovers, it can wait for existing AMs to contact RM back and then
> kill them forcefully before even starting a new AM. Worst case, RM will start
> a new AppAttempt after waiting for 10 mins ( the expiry interval). This way
> we'll minimize multiple AMs racing with each other. This can help issues with
> downstream components like Pig, Hive and Oozie during RM restart.
> In the mean while, new apps will proceed as usual as existing apps wait for
> recovery.
> This can continue to be useful after work-preserving restart, so that AMs
> which can properly sync back up with RM can continue to run and those that
> don't are guaranteed to be killed before starting a new attempt.
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