[jira] [Created] (KAFKA-13359) Round Robin Kafka Producer Routes to only half the partitions when even number of partitions

["David G (Jira)" <ji...@apache.org>]

David G created KAFKA-13359:
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             Summary: Round Robin Kafka Producer Routes to only half the partitions when even number of partitions
                 Key: KAFKA-13359
                 URL: https://issues.apache.org/jira/browse/KAFKA-13359
             Project: Kafka
          Issue Type: Bug
          Components: producer 
    Affects Versions: 3.0.0, 2.7.0
            Reporter: David G


When you have 1 message per batch, in the round robin Partitioner. The messages go only to half the partitions beacuse it always skips 1 partition. This works out for odd number of partitions because skipping 1 will mean all partitions get a hit eventually, but with an even number half the partitions never get selected.

 

So if you have partitions 1, 2, 3, 4 

Message 1: Partion 1

Message 2: Partion 3

Message 3: Partion 1 ... so on. [ Here 2 and 4 are never selected]

 

If you have partitions 1, 2, 3

Message 1: Partion 1

Message 2: Partion 3

Message 3: Partion 2 .. so on

 



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