Spark 0.9.0
Hi Spark devs,
I'm pretty sure this stacktrace is a bug in the way Spark is using the type
system but I don't quite know what it is. Something to do with type bounds
judging from my Googling.
Can someone with more Scala-foo than me please take a look? In the
meantime I'll be avoiding top() for a bit.
Thanks!
Andrew
This stracktrace came about when I called
val myRDD: RDD[(String,Int)] = ...
myRDD.reduceByKey(_+_).top(100)
But my toy example doesn't trigger the repro:
sc.parallelize(Seq( ("A",10), ("B",5), ("A",4), ("C", 15)
)).reduceByKey(_+_).top(2)
14/02/14 03:15:07 ERROR OneForOneStrategy:
scala.collection.immutable.$colon$colon cannot be cast to
org.apache.spark.util.BoundedPriorityQueue
java.lang.ClassCastException: scala.collection.immutable.$colon$colon
cannot be cast to org.apache.spark.util.BoundedPriorityQueue
at org.apache.spark.rdd.RDD$$anonfun$top$2.apply(RDD.scala:873)
at org.apache.spark.rdd.RDD$$anonfun$6.apply(RDD.scala:671)
at org.apache.spark.rdd.RDD$$anonfun$6.apply(RDD.scala:668)
at
org.apache.spark.scheduler.JobWaiter.taskSucceeded(JobWaiter.scala:56)
at
org.apache.spark.scheduler.DAGScheduler.handleTaskCompletion(DAGScheduler.scala:859)
at
org.apache.spark.scheduler.DAGScheduler.processEvent(DAGScheduler.scala:616)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$start$1$$anon$2$$anonfun$receive$1.applyOrElse(DAGScheduler.scala:207)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:498)
at akka.actor.ActorCell.invoke(ActorCell.scala:456)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:237)
at akka.dispatch.Mailbox.run(Mailbox.scala:219)
at
akka.dispatch.ForkJoinExecutorConfigurator$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)
