How to implement consumer Thread Safety with Spring-Kafka

Question

I'm using spring boot 2.1.7.RELEASE and spring-kafka 2.2.7.RELEASE.And I'm using @KafkaListener annotation to create a consumer and I'm using all default settings for the consumer.

Here is my consumer configuration :

@Configuration
@EnableKafka
public class KafkaConsumerCommonConfig implements KafkaListenerConfigurer {

      @Bean
      public <K,V> ConcurrentKafkaListenerContainerFactory<String, Object> kafkaListenerContainerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, Object> factory = new ConcurrentKafkaListenerContainerFactory<>();
        factory.setConsumerFactory(primaryConsumerFactory());
        factory.getContainerProperties().setMissingTopicsFatal(false);
        return factory;
      }

      @Bean
      public DefaultKafkaConsumerFactory<Object, Object> primaryConsumerFactory() {
        return new DefaultKafkaConsumerFactory<>(sapphireKafkaConsumerConfig.getConfigs());
      }

}

Because of some reasons, I've multiple consumers in the same application as shown below.

@KafkaListener(topics = "TEST_TOPIC1")
public void consumer1(){

}

@KafkaListener(topics = "TEST_TOPIC2")
public void consumer2(){

}

@KafkaListener(topics = "TEST_TOPIC3")
public void consumer3(){

}

With that said, as per the confluent document on 'Consumer Thread Safety'

You can’t have multiple consumers that belong to the same group in one thread and you can’t have multiple threads safely use the same consumer. One consumer per thread is the rule. To run mul‐ tiple consumers in the same group in one application, you will need to run each in its own thread. It is useful to wrap the con‐ sumer logic in its own object and then use Java’s ExecutorService to start multiple threads each with its own consumer.

Now my question is, should i do anything extra when using the above code using spring-kafka to address this scenario or Doesn't matter because the group would be generated randomly as I didn't specify? Please suggest.

Answer 1

All your listeners are configured for different topics. So, their group fully doesn't matter. The group comes to the scene when you have several consumers for the same topic.