Jason Gustafson created KAFKA-9232:
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Summary: Coordinator heartbeat completion does not work for
JoinGroup v3
Key: KAFKA-9232
URL: https://issues.apache.org/jira/browse/KAFKA-9232
Project: Kafka
Issue Type: Bug
Reporter: Jason Gustafson
Assignee: Sophie Blee-Goldman
For older versions of the JoinGroup API, the coordinator implements a static
timeout for new members of 5 minutes. This timeout is implemented using the
heartbeat purgatory and we expect that the delayed operation will be force
completed if the member successfully joins. This is implemented in
GroupCoordinator with the following logic:
{code:scala}
group.maybeInvokeJoinCallback(member, joinResult)
completeAndScheduleNextHeartbeatExpiration(group, member)
member.isNew = false
{code}
However, heartbeat completion depends on this check:
{code:scala}
def shouldKeepAlive(deadlineMs: Long): Boolean = {
if (isAwaitingJoin)
!isNew || latestHeartbeat + GroupCoordinator.NewMemberJoinTimeoutMs >
deadlineMs
else awaitingSyncCallback != null ||
latestHeartbeat + sessionTimeoutMs > deadlineMs
}
{code}
Since we invoke the join callback first, we will fall to the second branch.
This will only return true when the latest heartbeat plus session timeout
exceeds the deadline. The deadline in this case depends only on the statically
configured new member timeout, which means the heartbeat cannot complete until
about 5 minutes have passed. If the member falls out of the group before then,
then the heartbeat ultimately expires, which may trigger a spurious rebalance.
Newer versions of the protocol are not affected by this bug because we return
immediately the first time a member joins the group.
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