[jira] [Created] (KAFKA-2565) Offset Commit is not working if multiple consumers try to commit the offset

["Sreenivasulu Nallapati (JIRA)" <ji...@apache.org>]

Sreenivasulu Nallapati created KAFKA-2565:
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             Summary: Offset Commit is not working if multiple consumers try to commit the offset
                 Key: KAFKA-2565
                 URL: https://issues.apache.org/jira/browse/KAFKA-2565
             Project: Kafka
          Issue Type: Bug
          Components: consumer
    Affects Versions: 0.8.2.1, 0.8.1, 0.8.2.2
            Reporter: Sreenivasulu Nallapati
            Assignee: Neha Narkhede



We are seeing some strange behaviour with commitOffsets() method of kafka.javaapi.consumer.ConsumerConnector. We committing the offsets to zookeeper at the end of the consumer batch. We are running multiple consumers for the same topic.

Test details: 
1.	Created a topic with three partitions
2.	Started three consumers (cronjob) at the same time. The aim is that each consumer to process one partition.
3.	Each consumer at the end of the batch, it will call the commitOffsets() method on kafka.javaapi.consumer.ConsumerConnector
4.	The offsets are getting properly updated in zookeeper if we run the consumers for small set (say 1000 messages) of messages.
5.	But for larger number of messages, commit offset is not working as expected…sometimes only two offsets are properly committing and other one remains as it was.
6.	Please see the below example

Partition: 0 Latest Offset: 1057585
Partition: 1 Latest Offset: 1057715
Partition: 2 Latest Offset: 1057590
Earliest Offset after all consumers completed: {0=1057585, 1=724375, 2=1057590}

Highlighted in red supposed to be committed as 1057715 but it did not.

Please check if it is bug with multiple consumers. When multiple consumers are trying to update the same path in Zookeper, is there any synchronization issue?

Kafka Cluster details
1 zookeeper
3 brokers




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