Missing traceId in Kafka listener when consuming in batches

Trace info is lost and current span is null when consuming in batches from a KafkaListener.

I’m working with

• Spring Boot 2.3.3
• Spring Kafka 2.5.5
• Spring Cloud Starter Sleuth 2.4.4

I have a listener like

@KafkaListener(topics = "topic")
public void receiveMessage(List<String> messages) {
        messages.forEach(log::info);
}

And following property in application.yml: spring.kafka.listener.type: batch

If I remove the property then traceId is back

[jonatan-ivanov]

@KostasD21 I was able to repro this issue using your sample project, thanks for that (btw here’s some help for local Kafka).

As I was debugging it, I found that the batch and the non-batch scenarios are handled differently (see: KafkaMessageListenerContainer). This is so different that there are two different components that are calling your @KafkaListener.

The root cause is that the non-batch listener is decorated by Sleuth, while the batch listener is not. If you stop the execution in KafkaMessageListenerContainer where the listener or the batchListener is used you will see that one of them is proxied, the other one is not (by MessageListenerMethodInterceptor):

org.springframework.kafka.listener.adapter.RecordMessagingMessageListenerAdapter$$EnhancerBySpringCGLIB$$2296d4d9
org.springframework.kafka.listener.adapter.BatchMessagingMessageListenerAdapter

This explains why batch does not have traceIds so I looked into where the proxy is set-up: https://github.com/spring-cloud/spring-cloud-sleuth/blob/6b0ceb7ede2a8e3d842be72350c728628d199407/spring-cloud-sleuth-brave/src/main/java/org/springframework/cloud/sleuth/brave/instrument/messaging/SleuthKafkaAspect.java#L105-L109

Unfortunately this scenario is not supported which does make some sense since if there are 10 incoming messages with different traceIDs, which traceId would you pick to propagate to the consumer? If you would like this feature to be implemented, could you please open a new issue as a feature request (please reference this one)?

[jonatan-ivanov]

@Johny-Ch No, currently this is not supported. If there are 10 incoming messages with different traceIDs, which traceId would you pick to propagate to the consumer?