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https://issues.apache.org/jira/browse/FLINK-18451?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17171468#comment-17171468
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Till Rohrmann commented on FLINK-18451:
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How do you know on how many {{TaskManagers}} you have to wait before you can 
say that you have seen all task information?

> Flink HA on yarn may appear TaskManager double running when HA is restored
> --------------------------------------------------------------------------
>
>                 Key: FLINK-18451
>                 URL: https://issues.apache.org/jira/browse/FLINK-18451
>             Project: Flink
>          Issue Type: Bug
>          Components: Deployment / YARN
>    Affects Versions: 1.9.0
>            Reporter: ming li
>            Priority: Major
>              Labels: high-availability
>
> We found that when NodeManager is lost, the new JobManager will be restored 
> by Yarn's ResourceManager, and the Leader node will be registered on 
> Zookeeper. The original TaskManager will find the new JobManager through 
> Zookeeper and close the old JobManager connection. At this time, all tasks of 
> the TaskManager will fail. The new JobManager will directly perform job 
> recovery and recover from the latest checkpoint.
> However, during the recovery process, when a TaskManager is abnormally 
> connected to Zookeeper, it is not registered with the new JobManager in time. 
> Before the following timeout:
> 1. Connect with Zookeeper
> 2. Heartbeat with JobManager/ResourceManager
> Task will continue to run (assuming that Task can run independently in 
> TaskManager). Assuming that HA recovers fast enough, some Task double runs 
> will occur at this time.
> Do we need to make a persistent record of the cluster resources we allocated 
> during the runtime, and use it to judge all Task stops when HA is restored?



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