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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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Sital Kedia updated SPARK-13279:
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Description:
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 - Instead of an ArrayBuffer, we can use a LinkedHashSet which will
provide us o(1) lookup and also maintain the ordering.
was:
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 - Instead of an ArrayBuffer, we can use a LinkedHashSet which will
provide us o(1) lookup and also maintain the ordering.
> 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: Bug
> Components: Spark Core
> Affects Versions: 1.6.0
> Reporter: Sital Kedia
> Fix For: 1.6.0
>
>
> 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 - Instead of an ArrayBuffer, we can use a LinkedHashSet which will
> provide us o(1) lookup and also maintain the ordering.
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