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https://issues.apache.org/jira/browse/SPARK-2666?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14902459#comment-14902459
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Lianhui Wang edited comment on SPARK-2666 at 9/22/15 12:22 PM:
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[~imranr] thanks, i have take a look at https://github.com/squito/spark/pull/4.
this PR do not cancel running tasks of completed stage. i think when one
taskSet of stage has finished in TaskSchedulerImpl.taskSetFinished, running
tasks of this stage should be killed.
was (Author: lianhuiwang):
[~imranr] thanks, i have take a look at https://github.com/squito/spark/pull/4.
And i think that's logic is right.
> 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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