[Enhancement] Unnecessary broker back notification (notifyConsumerIdsChanged) in broadcast mode

[yx9o]

Before Creating the Enhancement Request

• I have confirmed that this should be classified as an enhancement rather than a bug/feature.

Summary

Hi, community, recently I found an unnecessary broker reverse notification (notifyConsumerIdsChanged) in broadcast mode.

Background: In one of our online incident investigations, there were thousands of single group broadcast clients, and it was found that the broker had been sending notifyConsumerIdsChanged requests to the broadcast clients.

Motivation

Analysis: In broadcast mode, each Consumer consumes complete data, and its rebalance operation only updates the messagequeue information, which is also updated by a scheduled task and has nothing to do with the change in the number of Consumers. So I think that in broadcast mode, if there is any change in Consumer, there is no need to send notifyConsumerIdsChanged requests to all broadcast clients.

Describe the Solution You'd Like

Modification: When sending ConsumerGroupEvent.CHANGE events in ConsumerManager, it is sent only when it is determined to be in non-broadcast mode.

Describe Alternatives You've Considered

No

Additional Context

No response