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https://issues.apache.org/jira/browse/KAFKA-345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14213469#comment-14213469
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Jiangjie Qin commented on KAFKA-345:
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Updated reviewboard https://reviews.apache.org/r/28025/diff/
 against branch origin/trunk

> Add a listener to ZookeeperConsumerConnector to get notified on rebalance 
> events
> --------------------------------------------------------------------------------
>
>                 Key: KAFKA-345
>                 URL: https://issues.apache.org/jira/browse/KAFKA-345
>             Project: Kafka
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 0.7, 0.8.0
>            Reporter: Peter Romianowski
>         Attachments: KAFKA-345.patch, KAFKA-345.patch, 
> KAFKA-345_2014-11-15_01:00:55.patch
>
>
> A sample use-case
> In our scenario we partition events by userid and then apply these to some 
> kind of state machine, that modifies the actual state of a user. So events 
> trigger state transitions. In order to avoid the need of loading user's state 
> upon each event processed, we cache that. But if a user's partition is moved 
> to another consumer and then back to the previous consumer we have stale 
> caches and hell breaks loose. I guess the same kind of problem occurs in 
> other scenarios like counting numbers by user, too.



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