[jira] [Closed] (FLINK-13635) Unexpectedly interrupted in AsyncFunction#timeout

["Biao Liu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-13635?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Biao Liu closed FLINK-13635.
----------------------------
    Resolution: Won't Fix

This scenario should not exist anymore after integrating AsyncWaitOperator with mailbox threading model. [~arvid.heise@gmail.com]

> Unexpectedly interrupted in AsyncFunction#timeout
> -------------------------------------------------
>
>                 Key: FLINK-13635
>                 URL: https://issues.apache.org/jira/browse/FLINK-13635
>             Project: Flink
>          Issue Type: Improvement
>          Components: API / DataStream
>    Affects Versions: 1.9.0
>            Reporter: Biao Liu
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.10.0
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> Currently the way of handling {{AsyncFunction#timeout}} is a bit weird in {{AsyncWaitOperator#processElement}}.
>  
> There are two methods in {{AsyncFunction}}, {{asyncInvoke}} and {{timeout}}. The {{asyncInvoke}} is executed in task thread, while the {{timeout}} is executed in system time service. When the {{asyncInvoke}} finished, it might complete the {{ResultFuture}}. Then it cancels the registered timer of {{timeout}}. However there is no any synchronization between the {{asyncInvoke}}, {{timeout}} and the cancelation. Moreover this cancelation is with interruption enabled.
> The {{timeout}} must be implemented very carefully. Because when the {{timeout}} is executing, there might be an interruption triggered at the same time (due to a completion of {{ResultFuture}}). That means the {{timeout}} must handle {{InterruptedException}} well everywhere if there is any operation reacting with this exception.
> My proposals are described below.
> 1. It should be written down in document that the {{asyncInvoke}} and {{timeout}} might be invoked at the same time.
> 2. This interruption of {{timeout}} should be avoided. There should be a synchronization between cancelation and {{timeout}}. If the {{timeout}} is executing, the cancelation should be avoided. If the cancelation has been invoked, this {{timeout}} should not be invoked anymore. Or we could simply cancel the timer without an interruption.
> CC [~kkl0u], [~till.rohrmann]



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