[
https://issues.apache.org/jira/browse/KAFKA-17154?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Kirk True updated KAFKA-17154:
------------------------------
Component/s: clients
> New consumer subscribe may join group without a call to consumer.poll
> ---------------------------------------------------------------------
>
> Key: KAFKA-17154
> URL: https://issues.apache.org/jira/browse/KAFKA-17154
> Project: Kafka
> Issue Type: Bug
> Components: clients, consumer
> Affects Versions: 3.8.0
> Reporter: Lianet Magrans
> Priority: Major
> Labels: kip-848-client-support
> Fix For: 4.0.0
>
>
> With the new consumer, a call to consumer.subscribe will update the client
> subscription state via a SubscriptionChangedEvent. This will be picked up by
> the background thread, and will send a Heartbeat RPC on the next poll of the
> background thread (without requiring a consumer.poll). This is a change in
> behaviour with the legacy consumer, that breaks the consumer#subscribe
> contract for "rebalances will only occur during an active call to \{@link
> #poll(Duration)}", so it should be fixed.
> In the legacy its a similar principle but different behaviour: subscribe
> changes the subscription state, and the coordinator picks it up to send the
> JoinRequest on the next poll of the coordinator (but this happens only as
> part of a consumer.poll)
> We should make the new consumer join (send HB to join) only on consumer.poll
> after a call to subscribed. We could consider having the
> SubscriptionChangedEvent only signal to the background that the subscription
> changed without doing the transition to JOINING that triggers the HB
> (membershipMgr#onSubscriptionUpdated could simply flip a flag, no
> transition), and then do the actual transition to JOINING when processing a
> PollEvent if the flag is on (flipping it back). (Just first simple approach
> that comes to mind, we should think about it a bit more and consider other
> interactions that could happen in between, like unsubscribe, close, etc).
> We should add test coverage to ensure the common behaviour with the legacy.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
