flink-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-8532) RebalancePartitioner should use Random value for its first partition
Date Tue, 21 Aug 2018 16:09:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-8532?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16587661#comment-16587661

ASF GitHub Bot commented on FLINK-8532:

Guibo-Pan commented on issue #6544: [FLINK-8532] [Streaming] modify RebalancePartitioner to
use a random partition as its first partition
URL: https://github.com/apache/flink/pull/6544#issuecomment-414729790
   Hi @tillrohrmann , does this PR look good to you, and could you help advance it? thanks.

This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:

> RebalancePartitioner should use Random value for its first partition
> --------------------------------------------------------------------
>                 Key: FLINK-8532
>                 URL: https://issues.apache.org/jira/browse/FLINK-8532
>             Project: Flink
>          Issue Type: Improvement
>          Components: DataStream API
>            Reporter: Yuta Morisawa
>            Assignee: Guibo Pan
>            Priority: Major
>              Labels: pull-request-available
> In some conditions, RebalancePartitioner doesn't balance data correctly because it
use the same value for selecting next operators.
> RebalancePartitioner initializes its partition id using the same value in every threads,
so it indeed balances data, but at one moment the amount of data in each operator is skew.
> Particularly, when the data rate of  former operators is equal , data skew becomes severe.
> Example:
> Consider a simple operator chain.
> -> map1 -> rebalance -> map2 ->
> Each map operator(map1, map2) contains three subtasks(subtask 1, 2, 3, 4, 5, 6).
> map1          map2
>  st1              st4
>  st2              st5
>  st3              st6
> At the beginning, every subtasks in map1 sends data to st4 in map2 because they use the
same initial parition id.
> Next time the map1 receive data st1,2,3 send data to st5 because they increment its partition
id when they processed former data.
> In my environment,  it takes twice the time to process data when I use RebalancePartitioner 
as long as I use other partitioners(rescale, keyby).
> To solve this problem, in my opinion, RebalancePartitioner should use its own operator
id for the initial value.

This message was sent by Atlassian JIRA

View raw message