kowshik commented on a change in pull request #9001:
URL: https://github.com/apache/kafka/pull/9001#discussion_r468101982
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File path: core/src/main/scala/kafka/controller/KafkaController.scala
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@@ -977,14 +1179,30 @@ class KafkaController(val config: KafkaConfig,
/**
* Send the leader information for selected partitions to selected brokers
so that they can correctly respond to
- * metadata requests
+ * metadata requests. Particularly, when feature versioning is enabled, we
filter out brokers with incompatible
+ * features from receiving the metadata requests. This is because we do not
want to activate incompatible brokers,
+ * as these may have harmful consequences to the cluster.
Review comment:
Good question. Yes, the broker will shut itself down. But still there is
a possible race condition that needs to be handled to prevent an incompatible
broker from causing damage to cluster. The race condition is described in the
KIP-584 [in this
section](https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Incompatiblebrokerlifetimeracecondition).
Please let me know your thoughts.
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