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https://issues.apache.org/jira/browse/SPARK-13279?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Owen updated SPARK-13279:
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Priority: Minor (was: Major)
Issue Type: Improvement (was: Bug)
> Spark driver stuck holding a global lock when there are 200k tasks submitted
> in a stage
> ---------------------------------------------------------------------------------------
>
> Key: SPARK-13279
> URL: https://issues.apache.org/jira/browse/SPARK-13279
> Project: Spark
> Issue Type: Improvement
> Components: Spark Core
> Affects Versions: 1.6.0
> Reporter: Sital Kedia
> Priority: Minor
>
> While running a large pipeline with 200k tasks, we found that the executors
> were not able to register with the driver because the driver was stuck
> holding a global lock in TaskSchedulerImpl.submitTasks function.
> jstack of the driver - http://pastebin.com/m8CP6VMv
> executor log - http://pastebin.com/2NPS1mXC
> From the jstack I see that the thread handing the resource offer from
> executors (dispatcher-event-loop-9) is blocked on a lock held by the thread
> "dag-scheduler-event-loop", which is iterating over an entire ArrayBuffer
> when adding a pending tasks. So when we have 200k pending tasks, because of
> this o(n2) operations, the driver is just hung for more than 5 minutes.
> Solution - In addPendingTask function, we don't really need a duplicate
> check. It's okay if we add a task to the same queue twice because
> dequeueTaskFromList will skip already-running tasks.
> Please note that this is a regression from Spark 1.5.
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