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https://issues.apache.org/jira/browse/SPARK-30511?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zebing Lin updated SPARK-30511:
-------------------------------
External issue ID: SPARK-2840
> Spark marks ended speculative tasks as pending leads to holding idle executors
> ------------------------------------------------------------------------------
>
> Key: SPARK-30511
> URL: https://issues.apache.org/jira/browse/SPARK-30511
> Project: Spark
> Issue Type: Bug
> Components: Scheduler
> Affects Versions: 2.3.0
> Reporter: Zebing Lin
> Priority: Major
>
> *TL;DR*
> When speculative tasks finished/failed/got killed, they are still considered
> as pending and count towards the calculation of number of needed executors.
> h3. Symptom
> In one of our production job (where it's running 4 tasks per executor), we
> found that it was holding 6 executors at the end with only 2 tasks running (1
> speculative). With more logging enabled, we found the job printed:
> {code:java}
> pendingTasks is 0 pendingSpeculativeTasks is 17 totalRunningTasks is 2
> {code}
> while the job only had 1 speculative task running and 16 speculative tasks
> intentionally killed because of corresponding original tasks had finished.
> h3. The Bug
> Upon examining the code of _pendingSpeculativeTasks_:
> {code:java}
> stageAttemptToNumSpeculativeTasks.map { case (stageAttempt, numTasks) =>
> numTasks -
> stageAttemptToSpeculativeTaskIndices.get(stageAttempt).map(_.size).getOrElse(0)
> }.sum
> {code}
> where _stageAttemptToNumSpeculativeTasks(stageAttempt)_ is incremented on
> _onSpeculativeTaskSubmitted_, but never decremented.
> _stageAttemptToNumSpeculativeTasks -= stageAttempt_ is performed on stage
> completion. *This means Spark is marking ended speculative tasks as pending,
> which leads to Spark to hold more executors that it actually needs!*
> I will have a PR ready to fix this issue, along with SPARK-2840 too
>
>
>
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