[jira] [Commented] (KAFKA-3890) Kafka Streams: task assignment is not maintained on cluster restart or rolling restart

["Henry Cai (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-3890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15343209#comment-15343209 ] 

Henry Cai commented on KAFKA-3890:
----------------------------------

PR: https://github.com/apache/kafka/pull/1538

> Kafka Streams: task assignment is not maintained on cluster restart or rolling restart
> --------------------------------------------------------------------------------------
>
>                 Key: KAFKA-3890
>                 URL: https://issues.apache.org/jira/browse/KAFKA-3890
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>            Reporter: Henry Cai
>            Assignee: Henry Cai
>              Labels: api, newbie
>
> Currently the task assignment in TaskAssignor is not deterministic.  During cluster restart or rolling restart, even though the participating worker nodes are the same, but the TaskAssignor is not able to maintain a deterministic mapping, so about 20% partitions will be reassigned which would cause state repopulation on cluster restart time.
> When the participating worker nodes are not changed, we really just want to keep the old task assignment.



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