[jira] [Commented] (ROCKETMQ-214) Improvement to help client to switch balance strategy smoothly

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ROCKETMQ-214?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16071191#comment-16071191 ] 

ASF GitHub Bot commented on ROCKETMQ-214:
-----------------------------------------

Github user lqjack commented on the issue:

    https://github.com/apache/incubator-rocketmq/pull/122
  
    yes


> Improvement to help client to switch balance strategy smoothly
> --------------------------------------------------------------
>
>                 Key: ROCKETMQ-214
>                 URL: https://issues.apache.org/jira/browse/ROCKETMQ-214
>             Project: Apache RocketMQ
>          Issue Type: Improvement
>          Components: rocketmq-client
>            Reporter: Jaskey Lam
>            Assignee: Xiaorui Wang
>
> In current implementations, rocketmq consumer will allocate message queue in client itself by fetching all clientid and all mq.
> While when user hopes to switch balance strategy,  some problem will be suffered in the intermediate state before all client instance have been change to the same new strategy.
> Say there are there clients with Strategy `AllocateMessageQueueAveragely`, when users needs to use their own `AllocateMessageQueueStrategy`, and they upgrade the client1 , and some mq will be missing to allocate or some mq allocate to multiple client instances, which will result in message duplication or message accumulation that fail to be consumed



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