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Miles Crawford edited comment on SPARK-18838 at 8/7/17 5:41 PM: ---------------------------------------------------------------- Can I get specific direction on the logs you'd like to see? I see bursts of lines like this: 2017-08-07 17:33:45,911 WARN org.apache.spark.scheduler.LiveListenerBus: Dropped 48996 SparkListenerEvents since Mon Aug 07 17:32:45 UTC 2017 2017-08-07 17:34:45,911 WARN org.apache.spark.scheduler.LiveListenerBus: Dropped 86057 SparkListenerEvents since Mon Aug 07 17:33:45 UTC 2017 And after a while we get in a state where every executor is idle, and the driver appears to still be waiting for results from executors, right in the middle of a stage. was (Author: milesc): Can I get specific direction on the logs you'd like to see? I see bursts of lines like this: bq. 2017-08-07 17:33:45,911 WARN org.apache.spark.scheduler.LiveListenerBus: Dropped 48996 SparkListenerEvents since Mon Aug 07 17:32:45 UTC 2017 bq. 2017-08-07 17:34:45,911 WARN org.apache.spark.scheduler.LiveListenerBus: Dropped 86057 SparkListenerEvents since Mon Aug 07 17:33:45 UTC 2017 bq. And after a while we get in a state where every executor is idle, and the driver appears to still be waiting for results from executors, right in the middle of a stage. > High latency of event processing for large jobs > ----------------------------------------------- > > Key: SPARK-18838 > URL: https://issues.apache.org/jira/browse/SPARK-18838 > Project: Spark > Issue Type: Improvement > Affects Versions: 2.0.0 > Reporter: Sital Kedia > Attachments: perfResults.pdf, SparkListernerComputeTime.xlsx > > > Currently we are observing the issue of very high event processing delay in > driver's `ListenerBus` for large jobs with many tasks. Many critical > component of the scheduler like `ExecutorAllocationManager`, > `HeartbeatReceiver` depend on the `ListenerBus` events and this delay might > hurt the job performance significantly or even fail the job. For example, a > significant delay in receiving the `SparkListenerTaskStart` might cause > `ExecutorAllocationManager` manager to mistakenly remove an executor which is > not idle. > The problem is that the event processor in `ListenerBus` is a single thread > which loops through all the Listeners for each event and processes each event > synchronously > https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/scheduler/LiveListenerBus.scala#L94. > This single threaded processor often becomes the bottleneck for large jobs. > Also, if one of the Listener is very slow, all the listeners will pay the > price of delay incurred by the slow listener. In addition to that a slow > listener can cause events to be dropped from the event queue which might be > fatal to the job. > To solve the above problems, we propose to get rid of the event queue and the > single threaded event processor. Instead each listener will have its own > dedicate single threaded executor service . When ever an event is posted, it > will be submitted to executor service of all the listeners. The Single > threaded executor service will guarantee in order processing of the events > per listener. The queue used for the executor service will be bounded to > guarantee we do not grow the memory indefinitely. The downside of this > approach is separate event queue per listener will increase the driver memory > footprint. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org