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https://issues.apache.org/jira/browse/KAFKA-3068?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15084478#comment-15084478
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Guozhang Wang commented on KAFKA-3068:
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Even without this caching, we can still potentially hit this issue if Kafka
nodes are migrating to a different cluster but with the same host, right?
> NetworkClient may connect to a different Kafka cluster than originally
> configured
> ---------------------------------------------------------------------------------
>
> Key: KAFKA-3068
> URL: https://issues.apache.org/jira/browse/KAFKA-3068
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 0.9.0.0
> Reporter: Jun Rao
>
> In https://github.com/apache/kafka/pull/290, we added the logic to cache all
> brokers (id and ip) that the client has ever seen. If we can't find an
> available broker from the current Metadata, we will pick a broker that we
> have ever seen (in NetworkClient.leastLoadedNode()).
> One potential problem this logic can introduce is the following. Suppose that
> we have a broker with id 1 in a Kafka cluster. A producer client remembers
> this broker in nodesEverSeen. At some point, we bring down this broker and
> use the host in a different Kafka cluster. Then, the producer client uses
> this broker from nodesEverSeen to refresh metadata. It will find the metadata
> in a different Kafka cluster and start producing data there.
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