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Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Note this is a joint worked work proposed by David Jacot, guozhang Wang and Jason Gustafson.

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public final class ConfigResource {
    /**
     * Type of resource.
     */
    public enum Type {
         GROUP((byte) 16), BROKER_LOGGER((byte) 8), BROKER((byte) 4), TOPIC((byte) 2), UNKNOWN((byte) 0);
    }
}

kafka-consumer-groups

--type 

The kafka-consumer-group command line tool will be extended to support the –type filter which allows to list or to describe groups implementing a specific type.

kafka-consumer-groups.sh -–bootstrap-server localhost:9092 -–list -–type <comma separated list of types>

kafka-consumer-groups.sh -–bootstrap-server localhost:9092 -–describe -–type <comma separated list of types>

--validate-regex 

The kafka-consumer-group command line tool will be extended to support the –validate-regex which allows to verify the regular expression use by a group to subscribe to topics.

kafka-consumer-groups.sh -–bootstrap-server localhost:9092 -–validate-regex <pattern>

Case Studies

Basic

Let’s look at a few examples to illustrate the rebalance logic. Let’s assume that the group is subscribed to the topic foo which has 3 partitions.

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• Group (epoch=0)
• Empty
• Target Assignment (epoch=0)
• Empty
• Member Assignment
• Empty

* The above format represents the group state as it is persisted in the __consumer_offsets topic.

Member A joins the group. The coordinator bumps the group epoch to 1, adds A to the group, and creates an empty member assignment.

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At this point B can transitions to epoch 1 but cannot get foo-2 until A revokes it. Note that the persisted target assignment of B already includes foo-2 here but B does not get it yet.

When A heartbeats, the group coordinator instructs him to revoke foo-2.

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