[jira] [Commented] (ROCKETMQ-192) Move consumer group rebalance from client to server ??

["Jaskey Lam (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ROCKETMQ-192?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16040016#comment-16040016 ] 

Jaskey Lam commented on ROCKETMQ-192:
-------------------------------------

They may see different view in some specific time window, but rebalance will be trigger every 10 seconds, at last they will see the same clientid so the rebalance result will be consistent eventually.

Rebalance in client side is easy enough and be able to balance across all brokers instead of balance inside one broker and sum them up. 

Also, and easy to extend user's own allocate strategy, without more obvious benefits, I don't think it's necessary.

> Move consumer   group rebalance  from client  to server  ??
> -----------------------------------------------------------
>
>                 Key: ROCKETMQ-192
>                 URL: https://issues.apache.org/jira/browse/ROCKETMQ-192
>             Project: Apache RocketMQ
>          Issue Type: Improvement
>          Components: rocketmq-client
>    Affects Versions: 4.2.0-incubating
>            Reporter: zhaoziyan
>            Assignee: Xiaorui Wang
>             Fix For: 4.2.0-incubating
>
>         Attachments: TestConsumerQueue.java
>
>
> Consumer Started.
> Consumer Started.
> Consumer Started.
> Consumer Started.
> RunHello [i=0, num=281]{/192.168.185.172:10911@2=31, /192.168.185.172:10911@0=125, /192.168.185.172:10911@1=125}
> RunHello [i=1, num=250]{/192.168.185.172:10911@2=125, /192.168.185.172:10911@3=125}
> RunHello [i=2, num=250]{/192.168.186.131:10911@1=125, /192.168.186.131:10911@0=125}
> RunHello [i=3, num=250]{/192.168.186.131:10911@3=125, /192.168.186.131:10911@2=125}
> SIZE=1000
> 重复31
> Here is my test，I send 1000 msg to the topic. 
> The Test show the client may consume the same queue in some case. because of the current Group rebalance is doing by the consumer side,in some case , the consumer may have diffent view of All Consumer ids.
> for Example: the consumer id 1 see have 3 consumers,but the consumer id 2 only see 2 consumers, so the same queue may hold by two consumer.
> Kakfa 0.8.2 to 0.9 have redesign the client, move the Group rebalance to server side, have we need also move the Rebalance to server side ??



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