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https://issues.apache.org/jira/browse/FLINK-33092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17812778#comment-17812778
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Maximilian Michels commented on FLINK-33092:
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+1 waiting on resources in the Executing state.
I think we need to just change the ScalingControler to delay triggering the
actual rescale process:
[https://github.com/apache/flink/blob/cb9e220c2291088459f0281aa8e8e8584436a9b2/flink-runtime/src/main/java/org/apache/flink/runtime/scheduler/adaptive/scalingpolicy/RescalingController.java#L37]
Right now, it triggers immediately on parallelism change. [~dmvk] can probably
answer this.
> Improve the resource-stabilization-timeout mechanism when rescale a job for
> Adaptive Scheduler
> ----------------------------------------------------------------------------------------------
>
> Key: FLINK-33092
> URL: https://issues.apache.org/jira/browse/FLINK-33092
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Coordination
> Reporter: Rui Fan
> Assignee: Rui Fan
> Priority: Major
> Attachments: image-2023-09-15-14-43-35-104.png
>
>
> !image-2023-09-15-14-43-35-104.png|width=916,height=647!
> h1. 1. Propose
> The above is the state transition graph when rescale a job in Adaptive
> Scheduler.
> In brief, when we trigger a rescale, the job will wait
> _*resource-stabilization-timeout*_ in WaitingForResources State when it has
> sufficient resources and it doesn't have the desired resource.
> If the _*resource-stabilization-timeout mechanism*_ is moved into the
> Executing State, the rescale downtime will be significantly reduced.
> h1. 2. Why the downtime is long?
> Currently, when rescale a job:
> * The Executing will transition to Restarting
> * The Restarting will cancel this job first.
> * The Restarting will transition to WaitingForResources after the whole job
> is terminal.
> * When this job has sufficient resources and it doesn't have the desired
> resource, the WaitingForResources needs to wait
> _*resource-stabilization-timeout*_ .
> * WaitingForResources will transition to CreatingExecutionGraph after
> resource-stabilization-timeout.
> The problem is the job isn't running during the
> resource-stabilization-timeout phase.
> h1. 3. How to reduce the downtime?
> We can move the _*resource-stabilization-timeout mechanism*_ into the
> Executing State when trigger a rescale. It means:
> * When this job has desired resources, the Executing can rescale directly.
> * When this job has sufficient resources and it doesn't have the desired
> resource, we can rescale after _*resource-stabilization-timeout.*_
> * The WaitingForResources will ignore the resource-stabilization-timeout
> after this improvement.
> The resource-stabilization-timeout works before cancel job, so the rescale
> downtime will be significantly reduced.
>
> Note: the resource-stabilization-timeout still works in WaitingForResources
> when start a job. It's just changed when rescale a job.
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