Set the number of kafka consumers in Springboot

You can configure the number of kafka consumers by “setConsumerFactory” method when creating factory

@Bean
public ConcurrentKafkaListenerContainerFactory<String, Crawler>
crawlJobKafkaListenerContainerFactory() {
    ConcurrentKafkaListenerContainerFactory<String, Crawler> factory
            = new ConcurrentKafkaListenerContainerFactory<>();
    factory.setConcurrency(3);
    factory.setConsumerFactory(crawlJobConsumerFactory());
    return factory;
}

# kafka-consumer-groups.sh — bootstrap-server localhost:9092 — describe — group job-group

Stay with the number of consumers not bigger than # of partitions.