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https://issues.apache.org/jira/browse/KAFKA-345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14211834#comment-14211834
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Neha Narkhede commented on KAFKA-345:
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[~becket_qin] Given that we are close to starting development on the new
consumer that exposes such a listener, just wondering what is the motivation
behind including one in the older consumer at this moment?
> 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
>
>
> 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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