Re: NullPointerExceptions when using val or broadcast on a standalone cluster.
Hi, I think this is a bug in Spark, because changing my program to using a main method instead of using the App trait fixes this problem. I've filed this as SPARK-2175, apologies if this turns out to be a duplicate. https://issues.apache.org/jira/browse/SPARK-2175 Regards, Brandon. -- View this message in context: http://apache-spark-user-list.1001560.n3.nabble.com/NullPointerExceptions-when-using-val-or-broadcast-on-a-standalone-cluster-tp7524p7797.html Sent from the Apache Spark User List mailing list archive at Nabble.com.
Re: NullPointerExceptions when using val or broadcast on a standalone cluster.
That stack trace is quite similar to the one that is generated when trying to do a collect within a closure. In this case, it feels "wrong" to collect in a closure, but I wonder what's reason behind the NPE. Curious to know whether they are related. Here's a very simple example: rrd1.flatMap(x=> rrd2.collect.flatMap(y=> List(y,x))) res7: org.apache.spark.rdd.RDD[Int] = FlatMappedRDD[10] at flatMap at :17 scala> res7.collect 14/06/13 01:11:48 INFO SparkContext: Starting job: collect at :19 14/06/13 01:11:48 INFO DAGScheduler: Got job 2 (collect at :19) with 3 output partitions (allowLocal=false) 14/06/13 01:11:48 INFO DAGScheduler: Final stage: Stage 4(collect at :19) 14/06/13 01:11:48 INFO DAGScheduler: Parents of final stage: List() 14/06/13 01:11:48 INFO DAGScheduler: Missing parents: List() 14/06/13 01:11:48 INFO DAGScheduler: Submitting Stage 4 (FlatMappedRDD[10] at flatMap at :17), which has no missing parents 14/06/13 01:11:48 INFO DAGScheduler: Submitting 3 missing tasks from Stage 4 (FlatMappedRDD[10] at flatMap at :17) 14/06/13 01:11:48 INFO TaskSchedulerImpl: Adding task set 4.0 with 3 tasks 14/06/13 01:11:48 INFO TaskSetManager: Starting task 4.0:0 as TID 16 on executor localhost: localhost (PROCESS_LOCAL) 14/06/13 01:11:48 INFO TaskSetManager: Serialized task 4.0:0 as 1850 bytes in 0 ms 14/06/13 01:11:48 INFO TaskSetManager: Starting task 4.0:1 as TID 17 on executor localhost: localhost (PROCESS_LOCAL) 14/06/13 01:11:48 INFO TaskSetManager: Serialized task 4.0:1 as 1850 bytes in 0 ms 14/06/13 01:11:48 INFO TaskSetManager: Starting task 4.0:2 as TID 18 on executor localhost: localhost (PROCESS_LOCAL) 14/06/13 01:11:48 INFO TaskSetManager: Serialized task 4.0:2 as 1850 bytes in 0 ms 14/06/13 01:11:48 INFO Executor: Running task ID 16 14/06/13 01:11:48 INFO Executor: Running task ID 17 14/06/13 01:11:48 INFO Executor: Running task ID 18 14/06/13 01:11:48 ERROR Executor: Exception in task ID 18 java.lang.NullPointerException at org.apache.spark.rdd.RDD.collect(RDD.scala:728) at $line45.$read$$iwC$$iwC$$iwC$$iwC$$anonfun$1.apply(:17) at $line45.$read$$iwC$$iwC$$iwC$$iwC$$anonfun$1.apply(:17) at scala.collection.Iterator$$anon$13.hasNext(Iterator.scala:371) at scala.collection.Iterator$class.foreach(Iterator.scala:727) at scala.collection.AbstractIterator.foreach(Iterator.scala:1157) at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48) at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:103) at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:47) at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:273) at scala.collection.AbstractIterator.to(Iterator.scala:1157) at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:265) at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1157) at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:252) at scala.collection.AbstractIterator.toArray(Iterator.scala:1157) at org.apache.spark.rdd.RDD$$anonfun$15.apply(RDD.scala:728) at org.apache.spark.rdd.RDD$$anonfun$15.apply(RDD.scala:728) at org.apache.spark.SparkContext$$anonfun$runJob$4.apply(SparkContext.scala:1079) at org.apache.spark.SparkContext$$anonfun$runJob$4.apply(SparkContext.scala:1079) at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:111) at org.apache.spark.scheduler.Task.run(Task.scala:51) at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:187) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:744) 14/06/13 01:11:48 ERROR Executor: Exception in task ID 16 ... same for each partition. Driver stacktrace: at org.apache.spark.scheduler.DAGScheduler.org $apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1037) at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1021) at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1019) at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59) at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47) at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1019) at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:637) at org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:637) at scala.Option.foreach(Option.scala:236) at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:637) at org.apache.spark.scheduler.DAGSchedulerEventProcessActor$$anonfun$receive$2.applyOrElse(DAGScheduler.scala:1211) 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.dispa
