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Jun Rao commented on KAFKA-2434: -------------------------------- [~andy_k], thanks for the patch. It seems the algorithm is following: during the round-robin iteration of all the partitions, it just skips over consumers not subscribing to a topic. While this seems to guarantee consistent assignment, it doesn't seem to guarantee uniform distribution. For example, consider the following case. There are 3 consumers c1, c2, and c3. c1 and c2 subscribe to topics t1, t2, and t3, and c3 subscribes to topic t1 only. Each topic has 2 partitions. The algorithm will sort the partitions in the following order: t1-p1, t2-p1, t3-p1, t1-p2, t2-p2, t3-p2, and iterate the consumers in the order of c1, c2, c3. In the end, it seems that t1-p1, t3-p1, t2-p2 will be assigned to c1 and t2-p1, t1-p2, t3-p2 will be assigned to c2, and c3 won't get any partitions. > remove roundrobin identical topic constraint in consumer coordinator (old API) > ------------------------------------------------------------------------------ > > Key: KAFKA-2434 > URL: https://issues.apache.org/jira/browse/KAFKA-2434 > Project: Kafka > Issue Type: Sub-task > Reporter: Andrew Olson > Assignee: Andrew Olson > Attachments: KAFKA-2434.patch > > > The roundrobin strategy algorithm improvement made in KAFKA-2196 should be > applied to the original high-level consumer API as well. -- This message was sent by Atlassian JIRA (v6.3.4#6332)