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https://issues.apache.org/jira/browse/SPARK-19502?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kay Ousterhout closed SPARK-19502.
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Resolution: Not A Problem
This code actually is currently needed to handle cases where a ShuffleMapTask
succeeds on an executor, but that executor was marked as failed (so the task
needs to be re-run), as described in this comment:
https://github.com/apache/spark/pull/16620#issuecomment-279125227
> Remove unnecessary code to re-submit stages in the DAGScheduler
> ---------------------------------------------------------------
>
> Key: SPARK-19502
> URL: https://issues.apache.org/jira/browse/SPARK-19502
> Project: Spark
> Issue Type: Bug
> Components: Scheduler
> Affects Versions: 1.1.1
> Reporter: Kay Ousterhout
> Assignee: Kay Ousterhout
> Priority: Minor
>
> There are a [few lines of code in the
> DAGScheduler](https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala#L1215)
> to re-submit shuffle map stages when some of the tasks fail. My
> understanding is that there should be a 1:1 mapping between pending tasks
> (which are tasks that haven't completed successfully) and available output
> locations, so that code should never be reachable. Furthermore, the approach
> taken by that code (to re-submit an entire stage as a result of task
> failures) is not how we handle task failures in a stage (the lower-level
> scheduler resubmits the individual tasks) which is what the 5-years-old TODO
> on that code seems to be implying should be done.
> The big caveat is that there's a bug being fixed in SPARK-19263 that means
> there is *not* a 1:1 relationship between pendingTasks and available
> outputLocations, so that code is serving as a (buggy) band-aid. This should
> be fixed once we resolve SPARK-19263.
> cc [~imranr] [~markhamstra] [[email protected]] (let me know if any of you
> see any reason we actually do need that code)
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