[
https://issues.apache.org/jira/browse/KAFKA-10643?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17225073#comment-17225073
]
A. Sophie Blee-Goldman commented on KAFKA-10643:
------------------------------------------------
Can you be a little more specific about the actual problem you're experiencing?
Is it just that the group seems to be rebalancing more often than you expected,
or are you concerned about the stuck rebalance and think that the "Preparing to
rebalance group..." log message is related to that? Either way, please upload
the broker and client side logs so we can better understand what's happening
I doubt that you hit KAFKA-9752 since that should be resolved in 2.6.0, unless
you saw that stuck rebalance on an older version. But there could be something
similar that hasn't been found yet. If you have the logs (both client and
broker) from that occurrence, that might help uncover the root cause.
Re: the DisconnectException, I suspect that it's unrelated especially if the
occurrence is not correlated with anything else you're seeing. It might suggest
an unstable network connection that should be looked into, but probably it's
not causing any harm
> Static membership - repetitive PreparingRebalance with updating metadata for
> member reason
> ------------------------------------------------------------------------------------------
>
> Key: KAFKA-10643
> URL: https://issues.apache.org/jira/browse/KAFKA-10643
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 2.6.0
> Reporter: Eran Levy
> Priority: Major
>
> Kafka streams 2.6.0, brokers version 2.6.0. Kafka nodes are healthy, kafka
> streams app is healthy.
> Configured with static membership.
> Every 10 minutes (I assume cause of topic.metadata.refresh.interval.ms), I
> see the following group coordinator log for different stream consumers:
> INFO [GroupCoordinator 2]: Preparing to rebalance group **--**-stream in
> state PreparingRebalance with old generation 12244 (__consumer_offsets-45)
> (reason: Updating metadata for member
> ****-stream-11-1-013edd56-ed93-4370-b07c-1c29fbe72c9a)
> (kafka.coordinator.group.GroupCoordinator)
> and right after that the following log:
> INFO [GroupCoordinator 2]: Assignment received from leader for group
> **-**-stream for generation 12246 (kafka.coordinator.group.GroupCoordinator)
>
> Looked a bit on the kafka code and Im not sure that I get why such a thing
> happening - is this line described the situation that happens here re the
> "reason:"?[https://github.com/apache/kafka/blob/7ca299b8c0f2f3256c40b694078e422350c20d19/core/src/main/scala/kafka/coordinator/group/GroupCoordinator.scala#L311]
> I also dont see it happening too often in other kafka streams applications
> that we have.
> The only thing suspicious that I see around every hour that different pods of
> that kafka streams application throw this exception:
> {"timestamp":"2020-10-25T06:44:20.414Z","level":"INFO","thread":"**-**-stream-94561945-4191-4a07-ac1b-07b27e044402-StreamThread-1","logger":"org.apache.kafka.clients.FetchSessionHandler","message":"[Consumer
>
> clientId=**-**-stream-94561945-4191-4a07-ac1b-07b27e044402-StreamThread-1-restore-consumer,
> groupId=null] Error sending fetch request (sessionId=34683236, epoch=2872)
> to node
> 3:","context":"default","exception":"org.apache.kafka.common.errors.DisconnectException:
> null\n"}
> I came across this strange behaviour after stated to investigate a strange
> stuck rebalancing state after one of the members left the group and caused
> the rebalance to stuck - the only thing that I found is that maybe because
> that too often preparing to rebalance states, the app might affected of this
> bug - KAFKA-9752 ?
> I dont understand why it happens, it wasn't before I applied static
> membership to that kafka streams application (since around 2 weeks ago).
> Will be happy if you can help me
>
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
