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TengYao Chi commented on KAFKA-17116: ------------------------------------- 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. -- This message was sent by Atlassian Jira (v8.20.10#820010)