[FLINK-9149] The creation of the ExecutionPlan fails when you combine a SideOutput with an SplitStream.

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: 1.4.2
• Component/s: API / DataStream
• Assignee: Unassigned
• Reporter: Fred Teunissen
• Created: 09/Apr/18 09:06
• Updated: 09/Apr/18 19:44
• Resolved: 09/Apr/18 19:44

Description

The creation of the ExecutionPlan fails when you combine a SideOutput with an SplitStream.

Code:

import org.apache.flink.streaming.api.functions.ProcessFunction
import org.apache.flink.streaming.api.scala._
import org.apache.flink.util.Collector

object SideOutputTest {
  def main(args: Array[String]) {
    val env = StreamExecutionEnvironment.getExecutionEnvironment
    env.setParallelism(3)

    val inputLongStream = env.generateSequence(0L, 100L)

    val filteredLongStream = inputLongStream.process(new LogFilterFunction)
    val splittedLongStream = filteredLongStream.split(l => Seq((l%4).toString))
    // workaround
    //  val splittedLongStream = filteredLongStream.map(x=>x).split(l => Seq((l%4).toString))

    val oneStream = splittedLongStream.select("1").map(l => l+1000)
    val twoStream = splittedLongStream.select("2").map(l => l+2000)
    val threeStream = splittedLongStream.select("3").map(l => l+3000)

    oneStream.union(twoStream, threeStream).print()

    val loggingStream = filteredLongStream.getSideOutput(loggingOutputTag)
    loggingStream.print()

    println(env.getExecutionPlan)

    env.execute()
  }

  val loggingOutputTag = OutputTag[String]("loggingStream")
}

class LogFilterFunction extends ProcessFunction[Long, Long] {
  override def processElement(value: Long, ctx: ProcessFunction[Long, Long]#Context, out: Collector[Long]): Unit = {
    if (value % 4 == 0) {
      ctx.output(SideOutputTest.loggingOutputTag, s"LogFilterFunction logging for $value")
    }    else {
      out.collect(value)
    }
  }
}

Exception:

Exception in thread "main" org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply$mcV$sp(JobManager.scala:897)
at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply(JobManager.scala:840)
at org.apache.flink.runtime.jobmanager.JobManager$$anonfun$handleMessage$1$$anonfun$applyOrElse$6.apply(JobManager.scala:840)
at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:39)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:415)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Caused by: java.lang.NullPointerException
at org.apache.flink.streaming.api.collector.selector.DirectedOutput.<init>(DirectedOutput.java:74)
at org.apache.flink.streaming.runtime.tasks.OperatorChain.createOutputCollector(OperatorChain.java:331)
at org.apache.flink.streaming.runtime.tasks.OperatorChain.createChainedOperator(OperatorChain.java:346)
at org.apache.flink.streaming.runtime.tasks.OperatorChain.createOutputCollector(OperatorChain.java:282)
at org.apache.flink.streaming.runtime.tasks.OperatorChain.<init>(OperatorChain.java:126)
at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:231)
at org.apache.flink.runtime.taskmanager.Task.run(Task.java:718)
at java.lang.Thread.run(Thread.java:748)

Workaround:

add a redundant map(x=>x) before the split function.

Issue Links

• duplicates: FLINK-9141 Calling getSideOutput() and split() on one DataStream causes NPE