Hi,folks

I wrote some spark jobs and these jobs could ran successfully when I ran them one by one. But if I ran them concurrently, for example 12 jobs parallel running, I met the following error. Could anybody tell me what cause this? How to solve it? Many Thanks!

Exception in thread "main" akka.actor.ActorNotFound: Actor not found for: ActorSelection[Anchor(akka.tcp://sparkDriver@130.1.10.108:23600/), Path(/user/MapOutputTracker)]
at akka.actor.ActorSelection$$anonfun$resolveOne$1.apply(ActorSelection.scala:65)
at akka.actor.ActorSelection$$anonfun$resolveOne$1.apply(ActorSelection.scala:63)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32)
at akka.dispatch.BatchingExecutor$Batch$$anonfun$run$1.processBatch$1(BatchingExecutor.scala:67)
at akka.dispatch.BatchingExecutor$Batch$$anonfun$run$1.apply$mcV$sp(BatchingExecutor.scala:82)
at akka.dispatch.BatchingExecutor$Batch$$anonfun$run$1.apply(BatchingExecutor.scala:59)
at akka.dispatch.BatchingExecutor$Batch$$anonfun$run$1.apply(BatchingExecutor.scala:59)
at scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:72)
at akka.dispatch.BatchingExecutor$Batch.run(BatchingExecutor.scala:58)
at akka.dispatch.ExecutionContexts$sameThreadExecutionContext$.unbatchedExecute(Future.scala:74)
at akka.dispatch.BatchingExecutor$class.execute(BatchingExecutor.scala:110)
at akka.dispatch.ExecutionContexts$sameThreadExecutionContext$.execute(Future.scala:73)
at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:40)
at scala.concurrent.impl.Promise$DefaultPromise.tryComplete(Promise.scala:248)
at akka.pattern.PromiseActorRef.$bang(AskSupport.scala:267)
at akka.remote.DefaultMessageDispatcher.dispatch(Endpoint.scala:89)
at akka.remote.EndpointReader$$anonfun$receive$2.applyOrElse(Endpoint.scala:937)
at akka.actor.Actor$class.aroundReceive(Actor.scala:465)
at akka.remote.EndpointActor.aroundReceive(Endpoint.scala:415)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516)
at akka.actor.ActorCell.invoke(ActorCell.scala:487)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:238)
at akka.dispatch.Mailbox.run(Mailbox.scala:220)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:393)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)