[jira] [Created] (FLINK-8385) Fix exceptions in AbstractEventTimeWindowCheckpointingITCase

["Stefan Richter (JIRA)" <ji...@apache.org>]

Stefan Richter created FLINK-8385:
-------------------------------------

             Summary: Fix exceptions in AbstractEventTimeWindowCheckpointingITCase
                 Key: FLINK-8385
                 URL: https://issues.apache.org/jira/browse/FLINK-8385
             Project: Flink
          Issue Type: Bug
          Components: State Backends, Checkpointing
    Affects Versions: 1.4.0
            Reporter: Stefan Richter
            Assignee: Stefan Richter
             Fix For: 1.5.0


When running all `AbstractEventTimeWindowCheckpointingITCase` with debug logging, I noticed two types of logged exceptions that should not happen:

1)
{code}
java.util.concurrent.RejectedExecutionException: Task org.apache.flink.runtime.state.SharedStateRegistry$AsyncDisposalRunnable@49258e6c rejected from java.util.concurrent.ThreadPoolExecutor@47e27938[Terminated, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 24]
	at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
	at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
	at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
	at org.apache.flink.runtime.state.SharedStateRegistry.scheduleAsyncDelete(SharedStateRegistry.java:197)
	at org.apache.flink.runtime.state.SharedStateRegistry.unregisterReference(SharedStateRegistry.java:162)
	at org.apache.flink.runtime.state.IncrementalKeyedStateHandle.discardState(IncrementalKeyedStateHandle.java:180)
	at org.apache.flink.util.LambdaUtil.applyToAllWhileSuppressingExceptions(LambdaUtil.java:51)
	at org.apache.flink.runtime.state.StateUtil.bestEffortDiscardAllStateObjects(StateUtil.java:54)
	at org.apache.flink.runtime.checkpoint.OperatorSubtaskState.discardState(OperatorSubtaskState.java:187)
	at org.apache.flink.runtime.checkpoint.OperatorState.discardState(OperatorState.java:108)
	at org.apache.flink.util.LambdaUtil.applyToAllWhileSuppressingExceptions(LambdaUtil.java:51)
	at org.apache.flink.runtime.state.StateUtil.bestEffortDiscardAllStateObjects(StateUtil.java:54)
	at org.apache.flink.runtime.checkpoint.CompletedCheckpoint.doDiscard(CompletedCheckpoint.java:229)
	at org.apache.flink.runtime.checkpoint.CompletedCheckpoint.discardOnShutdown(CompletedCheckpoint.java:198)
	at org.apache.flink.runtime.checkpoint.ZooKeeperCompletedCheckpointStore$2.apply(ZooKeeperCompletedCheckpointStore.java:351)
	at org.apache.flink.runtime.zookeeper.ZooKeeperStateHandleStore$RemoveBackgroundCallback.processResult(ZooKeeperStateHandleStore.java:640)
	at org.apache.curator.framework.imps.Backgrounding$1$1.run(Backgrounding.java:150)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
{code}

The cause of this exception is that disposal of an incremental state handle is triggered in another async thread and the shutdown proceeds to close the I/O Executor pool. This leads to RejectedExecutionException once the async deletes are triggered inside the registry. We need to wait for all pending ZK deletes before closing the I/O Executor pool.

2)
{code}
java.lang.Exception: Could not properly cancel managed keyed state future.
	at org.apache.flink.streaming.api.operators.OperatorSnapshotResult.cancel(OperatorSnapshotResult.java:91)
	at org.apache.flink.streaming.runtime.tasks.StreamTask$CheckpointingOperation.executeCheckpointing(StreamTask.java:1090)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.checkpointState(StreamTask.java:685)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.performCheckpoint(StreamTask.java:621)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpointOnBarrier(StreamTask.java:574)
	at org.apache.flink.streaming.runtime.io.BarrierBuffer.notifyCheckpoint(BarrierBuffer.java:380)
	at org.apache.flink.streaming.runtime.io.BarrierBuffer.processBarrier(BarrierBuffer.java:230)
	at org.apache.flink.streaming.runtime.io.BarrierBuffer.getNextNonBlocked(BarrierBuffer.java:185)
	at org.apache.flink.streaming.runtime.io.StreamInputProcessor.processInput(StreamInputProcessor.java:225)
	at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:69)
	at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:278)
	at org.apache.flink.runtime.taskmanager.Task.run(Task.java:724)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.concurrent.CancellationException
	at java.util.concurrent.FutureTask.report(FutureTask.java:121)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at org.apache.flink.util.FutureUtil.runIfNotDoneAndGet(FutureUtil.java:43)
	at org.apache.flink.runtime.state.StateUtil.discardStateFuture(StateUtil.java:69)
	at org.apache.flink.streaming.api.operators.OperatorSnapshotResult.cancel(OperatorSnapshotResult.java:89)
	... 12 more
{code}

This exception can be expected when the snapshot task is cancelled by closing the streams in blocking I/O. As an expected and safe exception, it should not be logged because it can easily confuse users.



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