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https://issues.apache.org/jira/browse/KAFKA-9232?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16983116#comment-16983116
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ASF GitHub Bot commented on KAFKA-9232:
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ableegoldman commented on pull request #7753: KAFKA-9232: Coordinator new
member heartbeat completion does not work for JoinGroup v3
URL: https://github.com/apache/kafka/pull/7753
The v3 JoinGroup logic does not properly complete the initial heartbeat for
new members, which then expires after the static 5 minute timeout. The core
issue is in the `shouldKeepAlive` method, which returns false when it should
return true.
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> Coordinator new member 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
> Priority: Major
>
> 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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