I'm reading data from a database using JdbcRDD, in Java, and I have an
implementation of Function0<Connection> whose instance I supply as the
'getConnection' parameter into the JdbcRDD constructor. Compiles fine.
The definition of the class/function is as follows:
public class GetDbConnection extends AbstractFunction0<Connection>
implements Serializable
where scala.runtime.AbstractFunction0 extends scala.Function0.
At runtime, I get an exception as below. Does anyone have an idea as to how
to resolve this/work around it? Thanks.
I'm running Spark 1.2.1 built for Hadoop 2.4.
Exception in thread "main" org.apache.spark.SparkException: Job aborted due
to stage failure: Task 3 in stage 0.0 failed 1 times, most recent failure:
Lost task 3.0 in stage 0.0 (TID 3, localhost): java.lang.ClassCastException:
cannot assign instance of com.kona.motivis.spark.proto.GetDbConnection to
field
org.apache.spark.rdd.JdbcRDD.org$apache$spark$rdd$JdbcRDD$$getConnection of
type scala.Function0 in instance of org.apache.spark.rdd.JdbcRDD
at
java.io.ObjectStreamClass$FieldReflector.setObjFieldValues(ObjectStreamClass.java:2083)
at
java.io.ObjectStreamClass.setObjFieldValues(ObjectStreamClass.java:1261)
at
java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1996)
at
java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
at
java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
at
java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
at
java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
at
java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
at
java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
at
java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
at
org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:62)
at
org.apache.spark.serializer.JavaSerializerInstance.deserialize(JavaSerializer.scala:87)
at
org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:57)
at org.apache.spark.scheduler.Task.run(Task.scala:56)
at
org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:200)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Driver stacktrace:
at
org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1214)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1203)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1202)
at
scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
at
scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
at
org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1202)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:696)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:696)
at scala.Option.foreach(Option.scala:236)
at
org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:696)
at
org.apache.spark.scheduler.DAGSchedulerEventProcessActor$$anonfun$receive$2.applyOrElse(DAGScheduler.scala:1420)
at akka.actor.Actor$class.aroundReceive(Actor.scala:465)
at
org.apache.spark.scheduler.DAGSchedulerEventProcessActor.aroundReceive(DAGScheduler.scala:1375)
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)
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