[jira] [Commented] (KAFKA-4229) Controller can't start after several zk expired event

["Guozhang Wang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-4229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15570973#comment-15570973 ] 

Guozhang Wang commented on KAFKA-4229:
--------------------------------------

I have assigned this JIRA to you [~pengwei]. BTW which version of Kafka were you testing? I saw the affected versions from 0.9.0.0 to 0.10.0.1, so not sure which version it is testing.

Also there are some known issues with the older versioned ZKClient such that events are not processed in exactly the firing order, and hence may cause various issues and cause some events be lost. ZkClient has been upgraded from older version to 0.10.0.x, I'm wondering if it has solved the problem or not.

> Controller can't start after several zk expired event
> -----------------------------------------------------
>
>                 Key: KAFKA-4229
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4229
>             Project: Kafka
>          Issue Type: Bug
>          Components: controller
>    Affects Versions: 0.9.0.0, 0.9.0.1, 0.10.0.0, 0.10.0.1
>            Reporter: Pengwei
>            Assignee: Pengwei
>
> We found the controller not started after several zk expired event in our test environment.  By analysing the log, I found the controller will handle the ephemeral node data delete event first and then the zk expired event , then the controller will gone.
> I can reproducer it on my develop env:
> 1. set up a one broker and one zk env, specify a very large zk timeout (20s)
> 2. stop the broker and remove the zk's /broker/ids/0  directory
> 3. restart the broker and make  a breakpoint in the zk client's event thread to queue the delete event.
> 4. after the /controller node gone the breakpoint will hit.
> 5. expired the current session(suspend the send thread) and create a new session s2
> 6. resume the event thread, then the controller will handle LeaderChangeListener.handleDataDeleted  and become leader
> 7. then controller will handle SessionExpirationListener.handleNewSession, it resign the controller and elect,  but when elect it found the /controller node is exist and not become the leader.  But the /controller node is created by current session s2 will not remove. So the controller is gone



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