[jira] [Updated] (FLINK-14375) Refactor task state updating to only notify scheduler about state changes that really happened

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

     [ https://issues.apache.org/jira/browse/FLINK-14375?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zhu Zhu updated FLINK-14375:
----------------------------
    Summary: Refactor task state updating to only notify scheduler about state changes that really happened  (was: Avoid to trigger failover on a non-effective task failure notification)

> Refactor task state updating to only notify scheduler about state changes that really happened
> ----------------------------------------------------------------------------------------------
>
>                 Key: FLINK-14375
>                 URL: https://issues.apache.org/jira/browse/FLINK-14375
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Runtime / Coordination
>    Affects Versions: 1.10.0
>            Reporter: Zhu Zhu
>            Assignee: Zhu Zhu
>            Priority: Major
>             Fix For: 1.10.0
>
>
> The DefaultScheduler triggers failover if a task is notified to be FAILED. However, in the case the multiple tasks in the same region fail together, it will trigger multiple failovers. The later triggered failovers are useless, lead to concurrent failovers and will increase the restart attempts count.
> I think the deep reason for this issue is that some fake state changes are notified to the DefaultScheduler.
> The case above is a FAILED state change from TM will turn a CANCELING vertex to CANCELED, and the actual state transition is to CANCELED. But a FAILED state is notified to DefaultScheduler.
> And there can be another possible issue caused by it, that a FINISHED state change is notified from TM when a vertex is CANCELING. The vertex will become CANCELED, while its FINISHED state change will be notified to DefaultScheduler which may trigger downstream task scheduling.
> I'd propose to fix it like this. 
>  - The DefaultScheduler does not handle the state update in SchedulerBase#updateTaskExecutionState.
>  - It only handles state transitions that really happened in ExecutionGraph (on Execution#transitionState or vertex reset).
> Besides avoiding fake state update, it also has a few other benefits:
> 1. we can get rid of the hack code in Execution#processFail
> 2. all states are possible to be notified to SchedulingStrategy, i.e. it solves FLINK-14233
> Here's the POC of this proposal https://github.com/zhuzhurk/flink/commits/refactor_state_update.



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