[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=17679249#comment-17679249 ] 

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

I created a pull request to resolve this problem. For a consumer execution vertex, when one of its consumed partition groups has a very large consumer vertex group (e.g. 1 v.s. 16, or 2 v.s. 32), this input will be ignored when computing the input locality.

> 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: Improvement
>          Components: Runtime / Coordination
>    Affects Versions: 1.16.0, 1.14.6, 1.15.3
>            Reporter: Zhu Zhu
>            Assignee: Zhu Zhu
>            Priority: Major
>              Labels: pull-request-available
>         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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