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https://issues.apache.org/jira/browse/KAFKA-17116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17869536#comment-17869536
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TengYao Chi commented on KAFKA-17116:
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Hello folks,
This is a very interesting discussion, and I have learned a lot from it. The
diverse perspectives shared here have been incredibly enlightening.
In my opinion, I think option_1 is the easier solution for this issue. As
[~chia7712] mentioned, it would be a challenge to deal with compatibility if we
select option_2, and it also needs additional logic to distinguish the member
state.
I’m also wondering if it is possible to achieve this without changing the
protocol. I think an additional field might be necessary.
The reason I support option_1 is that I have tried to implement a similar
solution in the current
[PR|https://github.com/apache/kafka/pull/16649/commits/9ee0e4e747fc1e851d736b173fdf881f844ba888#diff-0986b8c04dc1682e67717eb5e4a513e36d5fb9a3ab5ff4b90dd7efcd9b105712].
Compared to option_2, the solution is quite simple, and it could be even
simpler if we leverage `taggedFields` to send the temporary ID. In this way, we
also don’t need to change the protocol. We only need to add some simple logic
to handle the leave heartbeat without a correct memberId. The only concern will
be the UUID generation from the client side (according to [~chia7712] , maybe
this is not the case now).
> New consumer may not send effective leave group if member ID received after
> close
> ----------------------------------------------------------------------------------
>
> Key: KAFKA-17116
> URL: https://issues.apache.org/jira/browse/KAFKA-17116
> Project: Kafka
> Issue Type: Bug
> Components: clients, consumer
> Affects Versions: 3.8.0
> Reporter: Lianet Magrans
> Assignee: TengYao Chi
> Priority: Major
> Labels: kip-848-client-support
> Fix For: 3.9.0
>
>
> If the new consumer is closed after sending a HB to join, but before
> receiving the response to it, it will send a leave group request but without
> member ID (will simply fail with UNKNOWN_MEMBER_ID). This will make that the
> broker will have a registered new member, for which it will never receive a
> leave request for it.
> # consumer.subscribe -> sends HB to join, transitions to JOINING
> # consumer.close -> will transition to LEAVING and send HB with epoch -1
> (without waiting for in-flight requests)
> # consumer receives response to initial HB, containing the assigned member
> ID. It will simply ignore it because it's not in the group anymore
> (UNSUBSCRIBED)
> Note that the expectation, with the current logic, and main downsides of this
> are:
> # If the case was that the member received partitions on the first HB, those
> partitions won't be re-assigned (broker waiting for the closed consumer to
> reconcile them), until the rebalance timeout expires.
> # Even if no partitions were assigned to it, the member will remain in the
> group from the broker point of view (but not from the client POV). The member
> will be eventually kicked out for not sending HBs, but only when it's session
> timeout expires.
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