[ https://issues.apache.org/jira/browse/SPARK-26755?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Imran Rashid resolved SPARK-26755. ---------------------------------- Resolution: Fixed Fix Version/s: 3.0.0 Issue resolved by pull request 23677 [https://github.com/apache/spark/pull/23677] > Optimize Spark Scheduler to dequeue speculative tasks more efficiently > ---------------------------------------------------------------------- > > Key: SPARK-26755 > URL: https://issues.apache.org/jira/browse/SPARK-26755 > Project: Spark > Issue Type: Improvement > Components: Scheduler > Affects Versions: 3.0.0 > Reporter: Parth Gandhi > Assignee: Parth Gandhi > Priority: Minor > Fix For: 3.0.0 > > Attachments: Screen Shot 2019-01-28 at 11.21.05 AM.png, Screen Shot > 2019-01-28 at 11.21.25 AM.png, Screen Shot 2019-01-28 at 11.22.42 AM.png > > > Currently, Spark Scheduler takes quite some time to dequeue speculative tasks > for larger tasksets within a stage(like 100000 or more) when speculation is > turned on. On further analysis, it was found that the "task-result-getter" > threads remain blocked on one of the dispatcher-event-loop threads holding > the lock on TaskSchedulerImpl object > {code:java} > def resourceOffers(offers: IndexedSeq[WorkerOffer]): > Seq[Seq[TaskDescription]] = synchronized { > {code} > which takes quite some time to execute the method "dequeueSpeculativeTask" > in TaskSetManager.scala, thus, slowing down the overall running time of the > spark job. We were monitoring the time utilization of that lock for the whole > duration of the job and it was close to 50% i.e. the code within the > synchronized block would run for almost half the duration of the entire spark > job. The screenshots of the thread dump have been attached below for > reference. -- This message was sent by Atlassian JIRA (v7.6.14#76016) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org