Spring 卡夫卡监听器

Question

I am using KafkaListener to listen multiple topics and each topic has 20 partitions and below is my configuration. So here Does each topic will share same 20 threads (OR) each topic will get its own 20 threads?

import org.springframework.kafka.annotation.KafkaListener;

KafkaListener(topics = { "topic1", "topic2","topic3"},
        concurrency = "20",
        clientIdPrefix = "client1",
        groupId = "group1")

Answer 1

There will be 20 threads, each consuming from one partition of each topic.

If you want separate threads, you can add 3 @KafkaListener annotations to the method, each configured with 1 topic, or set the concurrency to 60 and use a custom partition assignor to make sure each consumer only gets one partition.