[jira] [Commented] (SPARK-2666) Always try to cancel running tasks when a stage is marked as zombie

["Thomas Graves (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-2666?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15176149#comment-15176149 ] 

Thomas Graves commented on SPARK-2666:
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[~lianhuiwang] were you going to work on this?  I'm running into this and I think its a bad idea to keep running the old tasks.  It all depends on what and how long those tasks are running.  In my case those tasks run a very long time doing an expensive shuffle. We should kill those tasks immediately to allow tasks from the newer retry Stage to run.

Did you run into issues with your pr or just needed rebase?

> Always try to cancel running tasks when a stage is marked as zombie
> -------------------------------------------------------------------
>
>                 Key: SPARK-2666
>                 URL: https://issues.apache.org/jira/browse/SPARK-2666
>             Project: Spark
>          Issue Type: Bug
>          Components: Scheduler, Spark Core
>            Reporter: Lianhui Wang
>
> There are some situations in which the scheduler can mark a task set as a "zombie" before the task set has completed all of its tasks.  For example:
> (a) When a task fails b/c of a {{FetchFailed}}
> (b) When a stage completes because two different attempts create all the ShuffleMapOutput, though no attempt has completed all its tasks (at least, this *should* result in the task set being marked as zombie, see SPARK-10370)
> (there may be others, I'm not sure if this list is exhaustive.)
> Marking a taskset as zombie prevents any *additional* tasks from getting scheduled, however it does not cancel all currently running tasks.  We should cancel all running to avoid wasting resources (and also to make the behavior a little more clear to the end user).  Rather than canceling tasks in each case piecemeal, we should refactor the scheduler so that these two actions are always taken together -- canceling tasks should go hand-in-hand with marking the taskset as zombie.
> Some implementation notes:
> * We should change {{taskSetManager.isZombie}} to be private and put it behind a method like {{markZombie}} or something.
> * marking a stage as zombie before the all tasks have completed does *not* necessarily mean the stage attempt has failed.  In case (a), the stage attempt has failed, but in stage (b) we are not canceling b/c of a failure, rather just b/c no more tasks are needed.
> * {{taskScheduler.cancelTasks}} always marks the task set as zombie.  However, it also has some side-effects like logging that the stage has failed and creating a {{TaskSetFailed}} event, which we don't want eg. in case (b) when nothing has failed.  So it may need some additional refactoring to go along w/ {{markZombie}}.
> * {{SchedulerBackend}}'s are free to not implement {{killTask}}, so we need to be sure to catch the {{UnsupportedOperationException}} s
> * Testing this *might* benefit from SPARK-10372



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