[jira] [Created] (KAFKA-6609) Offset commit reordering possible on coordinator disconnect

["Jason Gustafson (JIRA)" <ji...@apache.org>]

Jason Gustafson created KAFKA-6609:
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             Summary: Offset commit reordering possible on coordinator disconnect
                 Key: KAFKA-6609
                 URL: https://issues.apache.org/jira/browse/KAFKA-6609
             Project: Kafka
          Issue Type: Improvement
          Components: consumer
            Reporter: Jason Gustafson


When reconnecting to the coordinator following a disconnect, it is possible for offset commits sent prior to the disconnect to be received _after_ offset commits sent on the new connection. This is rare in practice because offset commits are not sent that frequently and there is some latency following a coordinator disconnect in order to rediscover the coordinator. I have, however, observed this happening in a failing system test. We were more likely to hit it in the test scenario due to KAFKA-6606, which caused more inflight offset commit requests than we would usually see.

I am not sure how important it is to fix this since the scenario is unlikely in practice, but one solution would be to steal a page from the the idempotent producer and add sequence numbers to offset commit requests.



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