Bug: Multiple Topics in @KafkaListener Stops Working After Upgrading to 3.3.2

[Andre-Satorres]

Affected Version

• Works in: 3.3.1
• Fails in: 3.3.2

Description

After upgrading from Spring Kafka 3.3.1 to 3.3.2, a @KafkaListener annotated method listening to multiple topics stopped working properly in tests.

I have two topics configured:

@Component
class EventKafkaConsumer(private val eventProcessor: EventProcessor) {

    @KafkaListener(topics = ["\${kafka.consumer.topic-a}", "\${kafka.consumer.topic-b}"])
    suspend fun listen(events: List<Event>) {
        eventProcessor.process(events)
    }
}

Observed Behavior

• I have two tests, each producing messages to a different topic.
• I have a single assert to check if any message was consumed by the application. I also added logs right under the KafkaListener method.
• When running both tests together, the second test always fails. There is no logs for the failed one, but I can see in the kafka the message there. It's just never consumed at all. Not even the deserializer is invoked.
• Running the second test alone, it passes. Proof that my implementation is correct, and it only fails when both run together.
• If I split the single @KafkaListener method into two separate methods, each with its own @KafkaListener, one for the first topic and another for the second topic, both tests pass.
• If I revert back to 3.3.1, keeping the single @KafkaListener for multiple topics, both tests pass.

Expected Behavior

• The same @KafkaListener should continue consuming from both topics in ** 3.3.2**, just like it does in 3.3.1.
• Running tests for both topics should not interfere with each other.

Steps to Reproduce

1. Use Spring Kafka 3.3.2.
2. Create a single @KafkaListener method listening to multiple topics.
3. Write two test cases, each producing messages to one of the topics, asserting that the messge was consumed.
4. Run both tests together: the second test always fails.
5. Run the second test alone: it passes.
6. Change to two separate @KafkaListener methods, one for each topic: both tests pass.
7. Downgrade to 3.3.1: both tests pass with a single @KafkaListener.

Additional Information

• Using "io.projectreactor.kafka:reactor-kafka"

Could this be a bug introduced in Spring Kafka or related to how Kafka consumers are initialized in 3.3.2?

[artembilan]

Any chances to have a simple project from you where we can reproduce the problem?
Thanks.