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https://issues.apache.org/jira/browse/KAFKA-12984?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17368542#comment-17368542
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A. Sophie Blee-Goldman commented on KAFKA-12984:
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[~mjsax] Technically yes, the issue with the SubscriptionState potentially
providing invalid "ownedPartitions" input can affect Kafka Streams as well.
However the impact for Streams is be considerably less severe, as the
assignment algorithm it doesn't make any assumptions about the previous
assignment being valid. The worst that should happen to a Streams application
is that the assignment could be slightly sub-optimal, with a partition/active
task being assigned to a member that had dropped out of the group since being
assigned that partition, instead of its true current owner.
> Cooperative sticky assignor can get stuck with invalid SubscriptionState
> input metadata
> ---------------------------------------------------------------------------------------
>
> Key: KAFKA-12984
> URL: https://issues.apache.org/jira/browse/KAFKA-12984
> Project: Kafka
> Issue Type: Bug
> Components: consumer
> Reporter: A. Sophie Blee-Goldman
> Assignee: A. Sophie Blee-Goldman
> Priority: Blocker
> Fix For: 3.0.0, 2.8.1
>
>
> Some users have reported seeing their consumer group become stuck in the
> CompletingRebalance phase when using the cooperative-sticky assignor. Based
> on the request metadata we were able to deduce that multiple consumers were
> reporting the same partition(s) in their "ownedPartitions" field of the
> consumer protocol. Since this is an invalid state, the input causes the
> cooperative-sticky assignor to detect that something is wrong and throw an
> IllegalStateException. If the consumer application is set up to simply retry,
> this will cause the group to appear to hang in the rebalance state.
> The "ownedPartitions" field is encoded based on the ConsumerCoordinator's
> SubscriptionState, which was assumed to always be up to date. However there
> may be cases where the consumer has dropped out of the group but fails to
> clear the SubscriptionState, allowing it to report some partitions as owned
> that have since been reassigned to another member.
> We should (a) fix the sticky assignment algorithm to resolve cases of
> improper input conditions by invalidating the "ownedPartitions" in cases of
> double ownership, and (b) shore up the ConsumerCoordinator logic to better
> handle rejoining the group and keeping its internal state consistent. See
> KAFKA-12983 for more details on (b)
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