[jira] [Commented] (KAFKA-4704) Group coordinator cache loading fails if groupId is used first for consumer groups and then for simple consumer

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-4704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15840637#comment-15840637 ] 

ASF GitHub Bot commented on KAFKA-4704:
---------------------------------------

GitHub user hachikuji opened a pull request:

    https://github.com/apache/kafka/pull/2455

    KAFKA-4704: Coordinator cache loading fails if groupId is reused for offset storage after group is removed

    

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/hachikuji/kafka KAFKA-4704

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/kafka/pull/2455.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #2455
    
----
commit 166e0d95dba89ba7ed9ff975b8353968316248bd
Author: Jason Gustafson <ja...@confluent.io>
Date:   2017-01-26T22:51:08Z

    KAFKA-4704: Coordinator cache loading fails if groupId is reused for offset storage after group is removed

----


> Group coordinator cache loading fails if groupId is used first for consumer groups and then for simple consumer
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: KAFKA-4704
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4704
>             Project: Kafka
>          Issue Type: Bug
>    Affects Versions: 0.10.0.0, 0.10.0.1, 0.10.1.0, 0.10.1.1
>            Reporter: Jason Gustafson
>            Assignee: Jason Gustafson
>             Fix For: 0.10.2.0
>
>
> When all the members in a consumer group have died and all of its offsets have expired, we write a tombstone to __consumer_offsets so that its group metadata is cleaned up. It is possible that after this happens, the same groupId is then used only for offset storage (i.e. by "simple" consumers). Our current cache loading logic, which is triggered when a coordinator first takes over control of a partition, does not account for this scenario and would currently fail.
> This is probably an unlikely scenario to hit in practice, but it reveals the lack of test coverage around the cache loading logic. We should improve this.



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