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https://issues.apache.org/jira/browse/KAFKA-1387?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Flavio Junqueira updated KAFKA-1387:
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Attachment: KAFKA-1387.patch
Given that it isn't clear that we will be getting curator as a dependency, I
started a fix that pretty much relies on the ZK handle that ZkClient creates.
Here is a preliminary patch that fixes the issues we have been discussing for
the consumer registration by simply not retrying the creation of the
registration znode across sessions. Given that I'm not using the ZkClient API,
there is a bit of wiring to be done, but I hope it is ok.
> Kafka getting stuck creating ephemeral node it has already created when two
> zookeeper sessions are established in a very short period of time
> ---------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: KAFKA-1387
> URL: https://issues.apache.org/jira/browse/KAFKA-1387
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.8.1.1
> Reporter: Fedor Korotkiy
> Assignee: Flavio Junqueira
> Priority: Blocker
> Labels: newbie, patch, zkclient-problems
> Attachments: KAFKA-1387.patch, kafka-1387.patch
>
>
> Kafka broker re-registers itself in zookeeper every time handleNewSession()
> callback is invoked.
> https://github.com/apache/kafka/blob/0.8.1/core/src/main/scala/kafka/server/KafkaHealthcheck.scala
>
> Now imagine the following sequence of events.
> 1) Zookeeper session reestablishes. handleNewSession() callback is queued by
> the zkClient, but not invoked yet.
> 2) Zookeeper session reestablishes again, queueing callback second time.
> 3) First callback is invoked, creating /broker/[id] ephemeral path.
> 4) Second callback is invoked and it tries to create /broker/[id] path using
> createEphemeralPathExpectConflictHandleZKBug() function. But the path is
> already exists, so createEphemeralPathExpectConflictHandleZKBug() is getting
> stuck in the infinite loop.
> Seems like controller election code have the same issue.
> I'am able to reproduce this issue on the 0.8.1 branch from github using the
> following configs.
> # zookeeper
> tickTime=10
> dataDir=/tmp/zk/
> clientPort=2101
> maxClientCnxns=0
> # kafka
> broker.id=1
> log.dir=/tmp/kafka
> zookeeper.connect=localhost:2101
> zookeeper.connection.timeout.ms=100
> zookeeper.sessiontimeout.ms=100
> Just start kafka and zookeeper and then pause zookeeper several times using
> Ctrl-Z.
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