[jira] [Created] (FLINK-19692) Can't restore feedback channel from savepoint

[Shang Yuanchun (Jira)]

Antti Kaikkonen created FLINK-19692:
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             Summary: Can't restore feedback channel from savepoint
                 Key: FLINK-19692
                 URL: https://issues.apache.org/jira/browse/FLINK-19692
             Project: Flink
          Issue Type: Bug
          Components: API / DataStream, API / State Processor, Stateful Functions
    Affects Versions: 1.11.2
            Reporter: Antti Kaikkonen


When using the new statefun-flink-datastream integration the following error is thrown by the *feedback -> union* task when trying to restore from a savepoint:
{code:java}
java.lang.Exception: Exception while creating StreamOperatorStateContext.
    at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.streamOperatorStateContext(StreamTaskStateInitializerImpl.java:204)
    at org.apache.flink.streaming.api.operators.AbstractStreamOperator.initializeState(AbstractStreamOperator.java:247)
    at org.apache.flink.streaming.runtime.tasks.OperatorChain.initializeStateAndOpenOperators(OperatorChain.java:290)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$beforeInvoke$0(StreamTask.java:479)
    at org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$1.runThrowing(StreamTaskActionExecutor.java:47)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.beforeInvoke(StreamTask.java:475)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:528)
    at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:721)
    at org.apache.flink.runtime.taskmanager.Task.run(Task.java:546)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.io.IOException: java.io.IOException: position out of bounds
    at org.apache.flink.runtime.state.StatePartitionStreamProvider.getStream(StatePartitionStreamProvider.java:58)
    at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.internalTimeServiceManager(StreamTaskStateInitializerImpl.java:235)
    at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.streamOperatorStateContext(StreamTaskStateInitializerImpl.java:167)
    ... 9 more
Caused by: java.io.IOException: position out of bounds
    at org.apache.flink.runtime.state.memory.ByteStreamStateHandle$ByteStateHandleInputStream.seek(ByteStreamStateHandle.java:124)
    at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl$KeyGroupStreamIterator.next(StreamTaskStateInitializerImpl.java:442)
    at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl$KeyGroupStreamIterator.next(StreamTaskStateInitializerImpl.java:395)
    at org.apache.flink.streaming.api.operators.StreamTaskStateInitializerImpl.internalTimeServiceManager(StreamTaskStateInitializerImpl.java:228)
    ... 10 more
{code}
 The error is only thrown when the feedback channel has been used.

I have tested with the [example application|https://github.com/apache/flink-statefun/blob/master/statefun-examples/statefun-flink-datastream-example/src/main/java/org/apache/flink/statefun/examples/datastream/Example.java] and the error is thrown only if it is modified to actually use the feedback channel. I simply modified the invoke method to sometimes forward the greeting to a random name:
{code:java}
@Override
public void invoke(Context context, Object input) {
  int seen = seenCount.updateAndGet(MyFunction::increment);
  context.send(GREETINGS, String.format("Hello %s at the %d-th time", input, seen));
  String[] names = {"Stephan", "Igal", "Gordon", "Seth", "Marta"};
  ThreadLocalRandom random = ThreadLocalRandom.current();
  int index = random.nextInt(names.length);
  final String name2 = names[index];
  if (random.nextDouble() < 0.5) context.send(new Address(GREET, name2), input);
}
{code}



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