[jira] [Closed] (FLINK-13063) AsyncWaitOperator shouldn't be releasing checkpointingLock

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

     [ https://issues.apache.org/jira/browse/FLINK-13063?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stefan Richter closed FLINK-13063.
----------------------------------
      Resolution: Fixed
    Release Note: This changes the default chaining behavior of the AsyncWaitOperator. By default, we now break chains so that the AsyncWaitOperator is never chained after another operator.

Merged in:
master: c773ce5

> AsyncWaitOperator shouldn't be releasing checkpointingLock
> ----------------------------------------------------------
>
>                 Key: FLINK-13063
>                 URL: https://issues.apache.org/jira/browse/FLINK-13063
>             Project: Flink
>          Issue Type: Bug
>          Components: API / DataStream
>    Affects Versions: 1.6.4, 1.7.2, 1.8.1, 1.9.0
>            Reporter: Piotr Nowojski
>            Assignee: Stefan Richter
>            Priority: Blocker
>              Labels: pull-request-available
>             Fix For: 1.9.0
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> 1.
> For the following setup of chained operators:
> {noformat}
> SourceOperator -> FlatMap -> AsyncOperator{noformat}
> Lets assume that input buffer of {{AsyncOperator}} is full. We start processing a record from the {{SourceOperator}}, we pass it to the {{FlatMap}}, which fan it out (multiplies it 10 times). First multiplied record reaches {{AsyncOperator}} and is special treated (stored in {{AsyncWaitOperator#pendingStreamElementQueueEntry}} ) and then {{AsyncWaitOperator}} waits (and releases) on the checkpoint lock (in {{AsyncWaitOperator#addAsyncBufferEntry}} . If a checkpoint is triggered now, both {{SourceOperator}} and {{FlatMap}} will be checkpointed assumed that all of those 10 multiplied records were processed, which is not true. Only the first one is checkpointed by the {{AsyncWatiOperator}}. Remaining 9 are not. So if we ever restore state from this checkpoint, we have lost those 9 records.
> 2.
> Similar issue (I think previously known) can happen if for example some upstream operator to the {{AsyncOperator}} fires a processing time timer, that emits some data. But in that case, {{AsyncWaitOperator#pendingStreamElementQueueEntry}} is being overwritten.
> 3.
> If upstream operator has the following pseudo code:
> {code:java}
> stateA = true
> output.collect(x)
> stateB = true{code}
> one would assume that stateA and stateB access/writes will be atomic from the perspective of the checkpoints. But again, because {{AsyncWaitOperator}} releases the checkpoint lock, they will not be.
> CC [~aljoscha] [~StephanEwen] [~srichter]



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