Lianet Magrans created KAFKA-18095:
--------------------------------------

             Summary: Consider allowing member to join without subscription 
under new consumer protocol
                 Key: KAFKA-18095
                 URL: https://issues.apache.org/jira/browse/KAFKA-18095
             Project: Kafka
          Issue Type: Improvement
          Components: group-coordinator
            Reporter: Lianet Magrans
            Assignee: David Jacot
             Fix For: 4.0.0


With the new consumer group protocol we currently enforce that members must 
provide subscribed topics or a regex when joining the group. This prevents 
members to join in cases where it subscribes to a java pattern for which the 
client-side resolution finds no matching topics.

If we relax this validation, we would end up with a more consistent behaviour 
for the regex subscriptions under the new protocol, given that currently, if 
the regex is resolved on the broker and finds no matching topics, the member is 
still allowed in the group (with no assignments), but if resolved on the client 
it doesn't join.

Also, the consumer could continue to guarantee that it joins after 
subscribe(Pattern), no matter if there are matching topics or not.

If we implement this change on the group coordinator, we also need to update 
the new consumer to actually attempt to join after a call to subscribe(Pattern) 
if no matching topics found (related jira)



--
This message was sent by Atlassian Jira
(v8.20.10#820010)

Reply via email to