[jira] [Commented] (KAFKA-12487) Sink connectors do not work with the cooperative consumer rebalance protocol

["Konstantine Karantasis (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-12487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17377785#comment-17377785 ] 

Konstantine Karantasis commented on KAFKA-12487:
------------------------------------------------

Just a note that for tickets that need to target a specific version, it's highly recommended (if not necessary) to add the fix versions field. Marked the issue as blocker for 3.0 and will be taking a look before code freeze, which approaches quickly. 

> Sink connectors do not work with the cooperative consumer rebalance protocol
> ----------------------------------------------------------------------------
>
>                 Key: KAFKA-12487
>                 URL: https://issues.apache.org/jira/browse/KAFKA-12487
>             Project: Kafka
>          Issue Type: Bug
>          Components: KafkaConnect
>    Affects Versions: 3.0.0, 2.4.2, 2.5.2, 2.8.0, 2.7.1, 2.6.2
>            Reporter: Chris Egerton
>            Assignee: Chris Egerton
>            Priority: Blocker
>             Fix For: 3.0.0
>
>
> The {{ConsumerRebalanceListener}} used by the framework to respond to rebalance events in consumer groups for sink tasks is hard-coded with the assumption that the consumer performs rebalances eagerly. In other words, it assumes that whenever {{onPartitionsRevoked}} is called, all partitions have been revoked from that consumer, and whenever {{onPartitionsAssigned}} is called, the partitions passed in to that method comprise the complete set of topic partitions assigned to that consumer.
> See the [WorkerSinkTask.HandleRebalance class|https://github.com/apache/kafka/blob/b96fc7892f1e885239d3290cf509e1d1bb41e7db/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerSinkTask.java#L669-L730] for the specifics.
>  
> One issue this can cause is silently ignoring to-be-committed offsets provided by sink tasks, since the framework ignores offsets provided by tasks in their {{preCommit}} method if it does not believe that the consumer for that task is currently assigned the topic partition for that offset. See these lines in the [WorkerSinkTask::commitOffsets method|https://github.com/apache/kafka/blob/b96fc7892f1e885239d3290cf509e1d1bb41e7db/connect/runtime/src/main/java/org/apache/kafka/connect/runtime/WorkerSinkTask.java#L429-L430] for reference.
>  
> This may not be the only issue caused by configuring a sink connector's consumer to use cooperative rebalancing. Rigorous unit and integration testing should be added before claiming that the Connect framework supports the use of cooperative consumers with sink connectors.



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