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https://issues.apache.org/jira/browse/KAFKA-3042?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15618260#comment-15618260
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Martin Nowak commented on KAFKA-3042:
-------------------------------------
Out of curiosity, why does the controller data also use an epoch, instead of
relying on ZooKeeper's data version and conditional updates of that?
While I understand the benefit of using epochs for partitions to reduce ZK load
[¹], moving the concurrency handling of the single /controller znode into Kafka
seems overly complex for no benefit.
[¹]:
https://cwiki.apache.org/confluence/display/KAFKA/Kafka+replication+detailed+design+V2
> updateIsr should stop after failed several times due to zkVersion issue
> -----------------------------------------------------------------------
>
> Key: KAFKA-3042
> URL: https://issues.apache.org/jira/browse/KAFKA-3042
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.8.2.1
> Environment: jdk 1.7
> centos 6.4
> Reporter: Jiahongchao
> Fix For: 0.10.2.0
>
> Attachments: controller.log, server.log.2016-03-23-01,
> state-change.log
>
>
> sometimes one broker may repeatly log
> "Cached zkVersion 54 not equal to that in zookeeper, skip updating ISR"
> I think this is because the broker consider itself as the leader in fact it's
> a follower.
> So after several failed tries, it need to find out who is the leader
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