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https://issues.apache.org/jira/browse/KAFKA-14639?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17706162#comment-17706162
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Guozhang Wang commented on KAFKA-14639:
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Had some chat with [~pnee] today regarding the client-side fix, I think a more
conservative fix may work, which is to only honor the old generation's owned
partitions if 1) it's the only participant claiming to own this partition, 2)
it's generation is no smaller than the current generation X minus 1. If its
generation is X-2 or less, then the above mentioned risk would materialize.
That being said, I still feel that the ultimate fix should touch on the broker
side, and hence would better be for the new rebalance protocol KIP.
> Kafka CooperativeStickyAssignor revokes/assigns partition in one rebalance
> cycle
> --------------------------------------------------------------------------------
>
> Key: KAFKA-14639
> URL: https://issues.apache.org/jira/browse/KAFKA-14639
> Project: Kafka
> Issue Type: Bug
> Components: clients, consumer
> Affects Versions: 3.2.1
> Reporter: Bojan Blagojevic
> Assignee: Philip Nee
> Priority: Major
> Attachments: consumers-jira.log
>
>
> I have an application that runs 6 consumers in parallel. I am getting some
> unexpected results when I use {{{}CooperativeStickyAssignor{}}}. If I
> understand the mechanism correctly, if the consumer looses partition in one
> rebalance cycle, the partition should be assigned in the next rebalance cycle.
> This assumption is based on the
> [RebalanceProtocol|https://kafka.apache.org/31/javadoc/org/apache/kafka/clients/consumer/ConsumerPartitionAssignor.RebalanceProtocol.html]
> documentation and few blog posts that describe the protocol, like [this
> one|https://www.confluent.io/blog/cooperative-rebalancing-in-kafka-streams-consumer-ksqldb/]
> on Confluent blog.
> {quote}The assignor should not reassign any owned partitions immediately, but
> instead may indicate consumers the need for partition revocation so that the
> revoked partitions can be reassigned to other consumers in the next rebalance
> event. This is designed for sticky assignment logic which attempts to
> minimize partition reassignment with cooperative adjustments.
> {quote}
> {quote}Any member that revoked partitions then rejoins the group, triggering
> a second rebalance so that its revoked partitions can be assigned. Until
> then, these partitions are unowned and unassigned.
> {quote}
> These are the logs from the application that uses
> {{{}protocol='cooperative-sticky'{}}}. In the same rebalance cycle
> ({{{}generationId=640{}}}) {{partition 74}} moves from {{consumer-3}} to
> {{{}consumer-4{}}}. I omitted the lines that are logged by the other 4
> consumers.
> Mind that the log is in reverse(bottom to top)
> {code:java}
> 2022-12-14 11:18:24 1 — [consumer-3] x.y.z.MyRebalanceHandler1 : New
> partition assignment: partition-59, seek to min common offset: 85120524
> 2022-12-14 11:18:24 1 — [consumer-3] x.y.z.MyRebalanceHandler2 : Partitions
> [partition-59] assigned successfully
> 2022-12-14 11:18:24 1 — [consumer-3] x.y.z.MyRebalanceHandler1 : Partitions
> assigned: [partition-59]
> 2022-12-14 11:18:24 1 — [consumer-3] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-3-my-client-id-my-group-id,
> groupId=my-group-id] Adding newly assigned partitions: partition-59
> 2022-12-14 11:18:24 1 — [consumer-3] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-3-my-client-id-my-group-id,
> groupId=my-group-id] Notifying assignor about the new
> Assignment(partitions=[partition-59])
> 2022-12-14 11:18:24 1 — [consumer-3] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-3-my-client-id-my-group-id,
> groupId=my-group-id] Request joining group due to: need to revoke partitions
> [partition-26, partition-74] as indicated by the current assignment and
> re-join
> 2022-12-14 11:18:24 1 — [consumer-3] x.y.z.MyRebalanceHandler2 : Partitions
> [partition-26, partition-74] revoked successfully
> 2022-12-14 11:18:24 1 — [consumer-3] x.y.z.MyRebalanceHandler1 : Finished
> removing partition data
> 2022-12-14 11:18:24 1 — [consumer-4] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-4-my-client-id-my-group-id,
> groupId=my-group-id] (Re-)joining group
> 2022-12-14 11:18:24 1 — [consumer-4] x.y.z.MyRebalanceHandler1 : New
> partition assignment: partition-74, seek to min common offset: 107317730
> 2022-12-14 11:18:24 1 — [consumer-4] x.y.z.MyRebalanceHandler2 : Partitions
> [partition-74] assigned successfully
> 2022-12-14 11:18:24 1 — [consumer-4] x.y.z.MyRebalanceHandler1 : Partitions
> assigned: [partition-74]
> 2022-12-14 11:18:24 1 — [consumer-4] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-4-my-client-id-my-group-id,
> groupId=my-group-id] Adding newly assigned partitions: partition-74
> 2022-12-14 11:18:24 1 — [consumer-4] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-4-my-client-id-my-group-id,
> groupId=my-group-id] Notifying assignor about the new
> Assignment(partitions=[partition-74])
> 2022-12-14 11:18:24 1 — [consumer-4] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-4-my-client-id-my-group-id,
> groupId=my-group-id] Request joining group due to: need to revoke partitions
> [partition-57] as indicated by the current assignment and re-join
> 2022-12-14 11:18:24 1 — [consumer-4] x.y.z.MyRebalanceHandler2 : Partitions
> [partition-57] revoked successfully
> 2022-12-14 11:18:24 1 — [consumer-4] x.y.z.MyRebalanceHandler1 : Finished
> removing partition data
> 2022-12-14 11:18:22 1 — [consumer-3] x.y.z.MyRebalanceHandler1 : Partitions
> revoked: [partition-26, partition-74]
> 2022-12-14 11:18:22 1 — [consumer-3] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-3-my-client-id-my-group-id,
> groupId=my-group-id] Revoke previously assigned partitions partition-26,
> partition-74
> 2022-12-14 11:18:22 1 — [consumer-3] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-3-my-client-id-my-group-id,
> groupId=my-group-id] Updating assignment with\n\tAssigned partitions:
> [partition-59]\n\tCurrent owned partitions: [partition-26,
> partition-74]\n\tAdded partitions (assigned - owned):
> [partition-59]\n\tRevoked partitions (owned - assigned): [partition-26,
> partition-74]
> 2022-12-14 11:18:22 1 — [consumer-3] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-3-my-client-id-my-group-id,
> groupId=my-group-id] Successfully synced group in generation
> Generation{generationId=640,
> memberId='partition-3-my-client-id-my-group-id-c31afd19-3f22-43cb-ad07-9088aa98d3af',
> protocol='cooperative-sticky'}
> 2022-12-14 11:18:22 1 — [consumer-3] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-3-my-client-id-my-group-id,
> groupId=my-group-id] Successfully joined group with generation
> Generation{generationId=640,
> memberId='partition-3-my-client-id-my-group-id-c31afd19-3f22-43cb-ad07-9088aa98d3af',
> protocol='cooperative-sticky'}
> 2022-12-14 11:18:22 1 — [consumer-4] x.y.z.MyRebalanceHandler1 : Partitions
> revoked: [partition-57]
> 2022-12-14 11:18:22 1 — [consumer-4] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-4-my-client-id-my-group-id,
> groupId=my-group-id] Revoke previously assigned partitions partition-57
> 2022-12-14 11:18:22 1 — [consumer-4] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-4-my-client-id-my-group-id,
> groupId=my-group-id] Updating assignment with\n\tAssigned partitions:
> [partition-74]\n\tCurrent owned partitions: [partition-57]\n\tAdded
> partitions (assigned - owned): [partition-74]\n\tRevoked partitions (owned -
> assigned): [partition-57]
> 2022-12-14 11:18:21 1 — [id-1] o.a.k.c.c.internals.ConsumerCoordinator :
> [Consumer clientId=partition-4-my-client-id-my-group-id, groupId=my-group-id]
> Successfully synced group in generation Generation{generationId=640,
> memberId='partition-4-my-client-id-my-group-id-ae2af665-edc9-4a8e-b658-98372d142477',
> protocol='cooperative-sticky'}
> 2022-12-14 11:18:21 1 — [consumer-4] o.a.k.c.c.internals.ConsumerCoordinator
> : [Consumer clientId=partition-4-my-client-id-my-group-id,
> groupId=my-group-id] Successfully joined group with generation
> Generation{generationId=640,
> memberId='partition-4-my-client-id-my-group-id-ae2af665-edc9-4a8e-b658-98372d142477',
> protocol='cooperative-sticky'} {code}
> Is this expected?
> Kafka client version is 3.2.1.
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