Running Flink's python examples

Question

I'm trying to run the python examples that come with Apache Flink 1.14.0 but keep getting errors. I installed per the instructions, and the .jar examples work fine, so I'm not sure what the issue is with the python.

For instance, the command ./bin/flink run --python /Users/[...]/flink-1.14.0/examples/python/datastream/word_count.py generates the following exception:

2021-11-05 23:04:11 org.apache.flink.runtime.JobException: Recovery is suppressed by NoRestartBackoffTimeStrategy at org.apache.flink.runtime.executiongraph.failover.flip1.ExecutionFailureHandler.handleFailure(ExecutionFailureHandler.java:138) at org.apache.flink.runtime.executiongraph.failover.flip1.ExecutionFailureHandler.getFailureHandlingResult(ExecutionFailureHandler.java:82) at org.apache.flink.runtime.scheduler.DefaultScheduler.handleTaskFailure(DefaultScheduler.java:228) at org.apache.flink.runtime.scheduler.DefaultScheduler.maybeHandleTaskFailure(DefaultScheduler.java:218) at org.apache.flink.runtime.scheduler.DefaultScheduler.updateTaskExecutionStateInternal(DefaultScheduler.java:209) at org.apache.flink.runtime.scheduler.SchedulerBase.updateTaskExecutionState(SchedulerBase.java:679) at org.apache.flink.runtime.scheduler.SchedulerNG.updateTaskExecutionState(SchedulerNG.java:79) at org.apache.flink.runtime.jobmaster.JobMaster.updateTaskExecutionState(JobMaster.java:444) at jav a.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564) at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.lambda$handleRpcInvocation$1(AkkaRpcActor.java:316) at org.apache.flink.runtime.concurrent.akka.ClassLoadingUtils.runWithContextClassLoader(ClassLoadingUtils.java:83) at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRpcInvocation(AkkaRpcActor.java:314) at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRpcMessage(AkkaRpcActor.java:217) at org.apache.flink.runtime.rpc.akka.FencedAkkaRpcActor.handleRpcMessage(FencedAkkaRpcActor.java:78) at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleMessage(AkkaRpcActor.java:163) at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:24) a t akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:20) at scala.PartialFunction.applyOrElse(PartialFunction.scala:123) at scala.PartialFunction.applyOrElse$(PartialFunction.scala:122) at akka.japi.pf.UnitCaseStatement.applyOrElse(CaseStatements.scala:20) at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171) at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:172) at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:172) at akka.actor.Actor.aroundReceive(Actor.scala:537) at akka.actor.Actor.aroundReceive$(Actor.scala:535) at akka.actor.AbstractActor.aroundReceive(AbstractActor.scala:220) at akka.actor.ActorCell.receiveMessage(ActorCell.scala:580) at akka.actor.ActorCell.invoke(ActorCell.scala:548) at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:270) at akka.dispatch.Mailbox.run(Mailbox.scala:231) at akka.dispatch.Mailbox.exec(Mailbox.scala:243) at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290) at java. base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016) at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665) at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598) at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183) Caused by: java.lang.ExceptionInInitializerError at org.apache.flink.streaming.api.runners.python.beam.BeamPythonFunctionRunner.createPythonExecutionEnvironment(BeamPythonFunctionRunner.java:401) at org.apache.flink.streaming.api.runners.python.beam.BeamPythonFunctionRunner.lambda$open$0(BeamPythonFunctionRunner.java:243) at org.apache.flink.runtime.memory.MemoryManager.lambda$getSharedMemoryResourceForManagedMemory$5(MemoryManager.java:539) at org.apache.flink.runtime.memory.SharedResources.createResource(SharedResources.java:126) at org.apache.flink.runtime.memory.SharedResources.getOrAllocateSharedResource(SharedResources.java:72) at org.apache.flink.runti me.memory.MemoryManager.getSharedMemoryResourceForManagedMemory(MemoryManager.java:555) at org.apache.flink.streaming.api.runners.python.beam.BeamPythonFunctionRunner.open(BeamPythonFunctionRunner.java:246) at org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.open(AbstractPythonFunctionOperator.java:131) at org.apache.flink.streaming.api.operators.python.AbstractOneInputPythonFunctionOperator.open(AbstractOneInputPythonFunctionOperator.java:116) at org.apache.flink.streaming.api.operators.python.PythonProcessOperator.open(PythonProcessOperator.java:59) at org.apache.flink.streaming.runtime.tasks.RegularOperatorChain.initializeStateAndOpenOperators(RegularOperatorChain.java:110) at org.apache.flink.streaming.runtime.tasks.StreamTask.restoreGates(StreamTask.java:711) at org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.call(StreamTaskActionExecutor.java:100) at org.apache.flink.streaming.runtime.tasks.Strea mTask.restoreInternal(StreamTask.java:687) at org.apache.flink.streaming.runtime.tasks.StreamTask.restore(StreamTask.java:654) at org.apache.flink.runtime.taskmanager.Task.runWithSystemExitMonitoring(Task.java:958) at org.apache.flink.runtime.taskmanager.Task.restoreAndInvoke(Task.java:927) at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:766) at org.apache.flink.runtime.taskmanager.Task.run(Task.java:575) at java.base/java.lang.Thread.run(Thread.java:832) Caused by: java.lang.UnsupportedOperationException: unsupported Java version: 14 at org.apache.beam.runners.core.construction.Environments$JavaVersion.forSpecification(Environments.java:106) at org.apache.beam.runners.core.construction.Environments.getJavaVersion(Environments.java:355) at org.apache.beam.runners.core.construction.Environments.getDefaultJavaSdkHarnessContainerUrl(Environments.java:402) at org.apache.beam.runners.core.construction.Environments.(Environments.java:119) ... 20 more

Answer 1

Have you followed the installation instructions ? For me, once I did

python -m pip install apache-flink==1.14.0

the examples ran successfully.

Answer 2

java.lang.UnsupportedOperationException: unsupported Java version: 14

The Java version seems to be wrong. Try installing another version.