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https://issues.apache.org/jira/browse/KAFKA-2729?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17396210#comment-17396210
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Jun Rao commented on KAFKA-2729:
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[~axrj]: If broker 5's ZK session expires and gets re-established, its broker
epoch will change. So, it's possible for broker 5 to receive and reject a
LeaderAndIsr request from the controller temporarily. The question is whether
broker 5 eventually receives the LeaderAndIsr request when the controller has
detected the new broker registration. This can be verified from the controller
and the state-change log.
> Cached zkVersion not equal to that in zookeeper, broker not recovering.
> -----------------------------------------------------------------------
>
> Key: KAFKA-2729
> URL: https://issues.apache.org/jira/browse/KAFKA-2729
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.8.2.1, 0.9.0.0, 0.10.0.0, 0.10.1.0, 0.11.0.0, 2.4.1
> Reporter: Danil Serdyuchenko
> Assignee: Onur Karaman
> Priority: Critical
> Fix For: 1.1.0
>
>
> After a small network wobble where zookeeper nodes couldn't reach each other,
> we started seeing a large number of undereplicated partitions. The zookeeper
> cluster recovered, however we continued to see a large number of
> undereplicated partitions. Two brokers in the kafka cluster were showing this
> in the logs:
> {code}
> [2015-10-27 11:36:00,888] INFO Partition
> [__samza_checkpoint_event-creation_1,3] on broker 5: Shrinking ISR for
> partition [__samza_checkpoint_event-creation_1,3] from 6,5 to 5
> (kafka.cluster.Partition)
> [2015-10-27 11:36:00,891] INFO Partition
> [__samza_checkpoint_event-creation_1,3] on broker 5: Cached zkVersion [66]
> not equal to that in zookeeper, skip updating ISR (kafka.cluster.Partition)
> {code}
> For all of the topics on the effected brokers. Both brokers only recovered
> after a restart. Our own investigation yielded nothing, I was hoping you
> could shed some light on this issue. Possibly if it's related to:
> https://issues.apache.org/jira/browse/KAFKA-1382 , however we're using
> 0.8.2.1.
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