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https://issues.apache.org/jira/browse/FLINK-7949?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aljoscha Krettek updated FLINK-7949:
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Priority: Critical (was: Major)
> AsyncWaitOperator is not restarting when queue is full
> ------------------------------------------------------
>
> Key: FLINK-7949
> URL: https://issues.apache.org/jira/browse/FLINK-7949
> Project: Flink
> Issue Type: Bug
> Components: Streaming
> Affects Versions: 1.3.2
> Reporter: Bartłomiej Tartanus
> Priority: Critical
> Original Estimate: 0.25h
> Remaining Estimate: 0.25h
>
> Issue was describe here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Checkpoint-was-declined-tasks-not-ready-td16066.html
> Issue - AsyncWaitOperator can't restart properly after failure (thread is
> waiting forever)
> Scenario to reproduce this issue:
> 1. The queue is full (let's assume that its capacity is N elements)
> 2. There is some pending element waiting, so the
> pendingStreamElementQueueEntry field in AsyncWaitOperator is not null and
> while-loop in addAsyncBufferEntry method is trying to add this element to
> the queue (but element is not added because queue is full)
> 3. Now the snapshot is taken - the whole queue of N elements is being
> written into the ListState in snapshotState method and also (what is more
> important) this pendingStreamElementQueueEntry is written to this list too.
> 4. The process is being restarted, so it tries to recover all the elements
> and put them again into the queue, but the list of recovered elements hold
> N+1 element and our queue capacity is only N. Process is not started yet, so
> it can not process any element and this one element is waiting endlessly.
> But it's never added and the process will never process anything. Deadlock.
> 5. Trigger is fired and indeed discarded because the process is not running
> yet.
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