Spring Cloud Stream - Is there a way to customize the StreamThread thread name?

Question

I'm using Spring Cloud Stream (Kafka as the binder) in my current project and the default thread name for StreamThread keeps me bothered as it is very long.

Here's what it looks like:

<applicationId>-<GUID>-StreamThread-1
someEvent-578fb764-3fba-4a54-9a34-ea9796053530-StreamThread-1

With this long thread name, it is hard to see the actual log message.

Would like to know if there's a way to configure the thread name.

I already tried the one below but it is not working:

@Bean
public ListenerContainerCustomizer<AbstractMessageListenerContainer<?, ?>> listenerCustomizer() {
    return (container, destinationName, group) -> {
        // Format to "[group].[destination]
        container.setBeanName(String.format("%s.%s", group, destinationName));
    };
}

Maybe I'm in the wrong config?

Side note: I enjoy using Spring Cloud Stream, and it is quite popular from what I see. But it keeps me wondering why I can't get any good documentation.

Edit: Solved the issue by adding spring.kafka.client-id in application.properties.

Having the client-id present, KafkaStreams will use the user-defined client-id as the thread name.

Answer 1

Are you sure that you use plain Kafka binder, but not Kafka Streams binder? That StreamThread gets its name like final String threadId = clientId + "-StreamThread-" + threadIdx;. See StreamThread source code. So, you need to be sure what is that clientId propagated down to Kafka Streams.

See StreamsConfig.CLIENT_ID_CONFIG which you can configure via spring.cloud.stream.kafka.streams.binder.applicationId property.

UPDATE

OK. I found the logic in the KafkaStreams:

    // The application ID is a required config and hence should always have value
    final String userClientId = config.getString(StreamsConfig.CLIENT_ID_CONFIG);
    final String applicationId = config.getString(StreamsConfig.APPLICATION_ID_CONFIG);
    if (userClientId.length() <= 0) {
        clientId = applicationId + "-" + processId;
    } else {
        clientId = userClientId;
    }
   ...
   final String baseName = clientId + "-StreamThread-";

So, the final thread name is based on that clientId exactly.

If that StreamsConfig.CLIENT_ID_CONFIG is empty, then it is based on the applicationId plus that processId. which might be indeed a GUID you mention.

Therefore consider to set that StreamsConfig.CLIENT_ID_CONFIG instead of an applicationId.