[jira] [Closed] (FLINK-13205) Checkpoints/savepoints injection has loose ordering properties when a stop-with-savepoint is triggered

["Kostas Kloudas (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-13205?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kostas Kloudas closed FLINK-13205.
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    Resolution: Fixed

Merged on master with 0c8c1d4b827700d788f5b4ddbd8a21192165d039
and on release-1.9 with b5aa6792bb04eaabb86bf9d73f12ec8441153f77

> Checkpoints/savepoints injection has loose ordering properties when a stop-with-savepoint is triggered
> ------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-13205
>                 URL: https://issues.apache.org/jira/browse/FLINK-13205
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / Checkpointing
>    Affects Versions: 1.9.0
>            Reporter: Alex
>            Assignee: Alex
>            Priority: Minor
>
> When a stop-with-savepoint is triggered at a source task, the task's dispatcher ({{Task.asyncCallDispatcher}})'s thread pool is extended (from single-threaded, it becomes multi-threaded).
> This leads to a race of applying consequent checkpoints/savepoints from dispatcher's queue at the same time and checkpoints/savepoints would be not strictly ordered in the event stream.
> As the result, checkpoints/savepoints that injected later than they should, may be "silently subsumed": potentially, they would be ignored and won't be reported to checkpoint coordinator.
> *Proposed solution:*
> Revert {{Task.asyncCallDispatcher}} behavior to be single-threaded.
> For stop-with-savepoint feature, the dispatcher's thread that performs the synchronous savepoint doesn't need to be blocking and {{StreamTask.finishTask()}} invocation can be delegated to {{StreamTask.notifyCheckpointComplete()}}.
> *Note:* imo, the issue described here is not critical, but the proposed change should simplify implementation. This ticket can be considered as enhancement.



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