Lianet Magrans created KAFKA-17116:
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Summary: New consumer may not send 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: consumer
Affects Versions: 3.8.0
Reporter: Lianet Magrans
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.
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