[jira] [Comment Edited] (FLINK-6319) Add timeout when shutting SystemProcessingTimeService down

["Till Rohrmann (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-6319?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15974260#comment-15974260 ] 

Till Rohrmann edited comment on FLINK-6319 at 4/19/17 7:50 AM:
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I totally understand the reasoning because you don't want a random timer task halting the shut down process of a {{Task}}. But this would then mean that we cannot guarantee that the {{LocalBufferPool}} is only shut down after the latency marker emission timer task has been completed (even with a small timeout this could still happen, but is much less likely).


was (Author: till.rohrmann):
This would then mean that we cannot guarantee that the {{LocalBufferPool}} is only shut down after the latency marker emission timer task has been completed (even with a small timeout this could still happen, but is much less likely).

> Add timeout when shutting SystemProcessingTimeService down
> ----------------------------------------------------------
>
>                 Key: FLINK-6319
>                 URL: https://issues.apache.org/jira/browse/FLINK-6319
>             Project: Flink
>          Issue Type: Improvement
>          Components: Local Runtime
>    Affects Versions: 1.3.0
>            Reporter: Till Rohrmann
>            Priority: Minor
>
> A user noted that we simply call {{shutdownNow}} on the {{SystemProcessingTimeService's}} {{ScheduledThreadpoolExecutor}} when calling {{SystemProcessingTimeService.shutdownService}}. {{shutdowNow}} will halt all waiting tasks but it won't wait until the currently running tasks have been completed. This can lead to unwanted runtime behaviours such as wrong termination orders when shutting down tasks (as reported in https://issues.apache.org/jira/browse/FLINK-4973?focusedCommentId=15965884&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15965884).
> I propose to add a small timeout to wait for currently running tasks to complete. Even though this problem cannot be completely solved since timer tasks might take longer than the specified timeout, a timeout for waiting for running tasks to complete will mitigate the problem.
> We can do this by calling {{timerServicer.awaitTermination(timeout, timeoutUnit);}} after the {{shutdowNow}} call.



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