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https://issues.apache.org/jira/browse/YARN-7913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17009329#comment-17009329
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Wilfred Spiegelenburg commented on YARN-7913:
---------------------------------------------
The ACL test case did not fail in the expected way when reversing the fix as
ACLs were not correctly setup in the test config.
Updating patch with the proper config. [^YARN-7913.003.patch]
> Improve error handling when application recovery fails with exception
> ---------------------------------------------------------------------
>
> Key: YARN-7913
> URL: https://issues.apache.org/jira/browse/YARN-7913
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: resourcemanager
> Affects Versions: 3.0.0
> Reporter: Gergo Repas
> Assignee: Wilfred Spiegelenburg
> Priority: Major
> Attachments: YARN-7913.000.poc.patch, YARN-7913.001.patch,
> YARN-7913.002.patch, YARN-7913.003.patch
>
>
> There are edge cases when the application recovery fails with an exception.
> Example failure scenario:
> * setup: a queue is a leaf queue in the primary RM's config and the same
> queue is a parent queue in the secondary RM's config.
> * When failover happens with this setup, the recovery will fail for
> applications on this queue, and an APP_REJECTED event will be dispatched to
> the async dispatcher. On the same thread (that handles the recovery), a
> NullPointerException is thrown when the applicationAttempt is tried to be
> recovered
> (https://github.com/apache/hadoop/blob/55066cc53dc22b68f9ca55a0029741d6c846be0a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FairScheduler.java#L494).
> I don't see a good way to avoid the NPE in this scenario, because when the
> NPE occurs the APP_REJECTED has not been processed yet, and we don't know
> that the application recovery failed.
> Currently the first exception will abort the recovery, and if there are X
> applications, there will be ~X passive -> active RM transition attempts - the
> passive -> active RM transition will only succeed when the last APP_REJECTED
> event is processed on the async dispatcher thread.
> _The point of this ticket is to improve the error handling and reduce the
> number of passive -> active RM transition attempts (solving the above
> described failure scenario isn't in scope)._
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