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https://issues.apache.org/jira/browse/KAFKA-16984?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kirk True updated KAFKA-16984:
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Labels: kip-848 kip-848-client-support (was: kip-848)
> New consumer should not complete leave operation until it gets a response
> -------------------------------------------------------------------------
>
> Key: KAFKA-16984
> URL: https://issues.apache.org/jira/browse/KAFKA-16984
> Project: Kafka
> Issue Type: Bug
> Components: clients, consumer
> Affects Versions: 3.8.0
> Reporter: Lianet Magrans
> Assignee: Lianet Magrans
> Priority: Major
> Labels: kip-848, kip-848-client-support
> Fix For: 3.9.0
>
>
> When the new consumer attempts to leave a group, it sends a leave group
> request in a fire-and-forget mode, so, as soon as the request is generated,
> it will:
> 1. transitions to UNSUBSCRIBED
> 2. complete the leaveGroup operation future
> This task focus on point 2, which has the undesired side-effect that whatever
> might have been waiting for the leave to do something else, will carry on,
> ex. consumer close, leading to responses to disconnected clients we've seen
> when running stress tests)
> When leaving a group while closing a consumer, the member sends the leave
> request and moves on to next operation, which is closing the network thread,
> so we end up with disconnected client receiving responses from the server. We
> should send leave group heartbeat, and transition to UNSUBSCRIBE, but only
> complete the leave operation when we get a response for it, which is a much
> more accurate confirmation that the consumer left the group and can move on
> with other operations.
> Note that the legacy consumer does wait for a leave response before closing
> down the coordinator (see
> [AbstractCoordinator|https://github.com/apache/kafka/blob/25230b538841a5e7256b1b51725361dd59435901/clients/src/main/java/org/apache/kafka/clients/consumer/internals/AbstractCoordinator.java#L1135-L1140]),
> we we are looking to have the same behaviour on the new consumer.
> Note that with this task we'll only focus on changing the behaviour for the
> leave operation completion (point 2 above) to tidy up the close flow. We are
> not changing the transition to UNSUBSCRIBED, as it would require further
> consideration if ever needed.
>
> This is also a building block for future improvements around error handling
> for the leave request, which we don't have at the moment (related Jira linked)
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