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https://issues.apache.org/jira/browse/KAFKA-4696?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16512722#comment-16512722
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Richard Yu commented on KAFKA-4696:
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Hi, I will probably restart my work on this.
> Streams standby task assignment should be state-store aware
> -----------------------------------------------------------
>
> Key: KAFKA-4696
> URL: https://issues.apache.org/jira/browse/KAFKA-4696
> Project: Kafka
> Issue Type: Sub-task
> Components: streams
> Affects Versions: 0.10.2.0, 0.11.0.0
> Reporter: Damian Guy
> Assignee: Richard Yu
> Priority: Major
>
> Task Assignment is currently not aware of which tasks have State Stores. This
> can result in uneven balance of standby task assignment as all tasks are
> assigned, but only those tasks with state-stores are ever created by
> {{StreamThread}}. So what seems like an optimal strategy during assignment
> time could be sub-optimal post-assignment.
> For example, lets say we have 4 tasks (2 with state-stores), 2 clients,
> numStandbyReplicas = 1. Each client would get 2 active and 2 standby tasks.
> One of the clients may end up with both state-store tasks, while the other
> has none.
> Further to this, standby task configuration is currently "all or nothing". It
> might make sense to allow more fine grained configuration, i.e., the ability
> to specify the number of standby replicas individually for each stateful
> operator.
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