[jira] [Commented] (FLINK-15325) Input location preference which affects task distribution may make certain job performance worse

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

    [ https://issues.apache.org/jira/browse/FLINK-15325?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16999895#comment-16999895 ] 

Zhu Zhu commented on FLINK-15325:
---------------------------------

[~trohrmann] do you think we should have such a config to switch on/off input location preferences, so that there is a way to force tasks to be evenly distributed with it as well as "cluster.evenly-spread-out-slots"?

> Input location preference which affects task distribution may make certain job performance worse 
> -------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-15325
>                 URL: https://issues.apache.org/jira/browse/FLINK-15325
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / Coordination
>    Affects Versions: 1.10.0
>            Reporter: Zhu Zhu
>            Priority: Major
>         Attachments: D58ADB03-7187-46B1-B077-91E5005FD463.png
>
>
> When running TPC-DS jobs in a session cluster, we observed that sometimes tasks are not evenly distributed in TMs. The root cause turned out to be that the downstream tasks tend to be TM or host local with its input tasks. This helps to reduce network shuffle. 
> However, in certain cases, like the topology presented in the attached image, jamming the input task's TM and machine with downstream tasks would affect the performance. In this case, respecting input location preferences is causing troubles more than bringing benefits.
> So I'm wondering whether we should introduce a config so that users can disable input location preferences?



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