Aaron Davidson created SPARK-1769: ------------------------------------- Summary: Executor loss can cause race condition in Pool Key: SPARK-1769 URL: https://issues.apache.org/jira/browse/SPARK-1769 Project: Spark Issue Type: Bug Components: Spark Core Affects Versions: 1.0.0 Reporter: Aaron Davidson
Loss of executors (in this case due to OOMs) exposes a race condition in Pool.scala, evident from this stack trace: {code} 14/05/08 22:41:48 ERROR OneForOneStrategy: java.lang.NullPointerException at org.apache.spark.scheduler.Pool$$anonfun$executorLost$1.apply(Pool.scala:87) at org.apache.spark.scheduler.Pool$$anonfun$executorLost$1.apply(Pool.scala:87) at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59) at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47) at org.apache.spark.scheduler.Pool.executorLost(Pool.scala:87) at org.apache.spark.scheduler.Pool$$anonfun$executorLost$1.apply(Pool.scala:87) at org.apache.spark.scheduler.Pool$$anonfun$executorLost$1.apply(Pool.scala:87) at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59) at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47) at org.apache.spark.scheduler.Pool.executorLost(Pool.scala:87) at org.apache.spark.scheduler.TaskSchedulerImpl.removeExecutor(TaskSchedulerImpl.scala:412) at org.apache.spark.scheduler.TaskSchedulerImpl.executorLost(TaskSchedulerImpl.scala:385) at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend$DriverActor.removeExecutor(CoarseGrainedSchedulerBackend.scala:160) at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend$DriverActor$$anonfun$receive$1$$anonfun$applyOrElse$5.apply(CoarseGrainedSchedulerBackend.scala:123) at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend$DriverActor$$anonfun$receive$1$$anonfun$applyOrElse$5.apply(CoarseGrainedSchedulerBackend.scala:123) at scala.Option.foreach(Option.scala:236) at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend$DriverActor$$anonfun$receive$1.applyOrElse(CoarseGrainedSchedulerBackend.scala:123) at akka.actor.ActorCell.receiveMessage(ActorCell.scala:498) at akka.actor.ActorCell.invoke(ActorCell.scala:456) at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:237) at akka.dispatch.Mailbox.run(Mailbox.scala:219) at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:386) at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) {code} Note that the line of code that throws this exception is here: {code} schedulableQueue.foreach(_.executorLost(executorId, host)) {code} By the stack trace, it's not schedulableQueue that is null, but an element therein. As far as I could tell, we never add a null element to this queue. Rather, I could see that there removeSchedulable() and executorLost() were called at about the same time (via log messages), and suspect that since this ArrayBuffer is in no way synchronized, that we iterate through the list while it's in an incomplete state. -- This message was sent by Atlassian JIRA (v6.2#6252)