[FLINK-19692] Can't restore feedback channel from savepoint

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: statefun-2.0.0, statefun-2.1.0, statefun-2.2.0
• Fix Version/s: statefun-2.2.1
• Component/s: Stateful Functions
• Labels: pull-request-available
• Assignee: Igal Shilman
• Reporter: Antti Kaikkonen
• Created: 18/Oct/20 05:34
• Updated: 11/Nov/20 09:01
• Resolved: 29/Oct/20 03:39

Description

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:

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

 The error is only thrown when the feedback channel has been used.

I have tested with the example application 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:

@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);
}

Issue Links

• is caused by: FLINK-19741 InternalTimeServiceManager fails to restore due to corrupt reads if there are other users of raw keyed state streams
• is caused by: FLINK-19748 KeyGroupRangeOffsets#KeyGroupOffsetsIterator should skip key groups that don't have a defined offset
• links to: GitHub Pull Request #168