CODEWITHSUNDEEP
javaspring-bootapache-kafkaspring-kafka
yifei
yifei

Reputation: 601

How to read 2 Kafka topics sequentially in one consumer class using spring boot?

I have 2 Kafka topics A and B. I want that every time when my consumer starts up, it goes to topic A first. Topic A contains information about topic B, and I'll depend on that information to fetch data from topic B.

So essentially I need to read topic A first before going to topic B, and I just need to do this once upon every restart of my program.

Things I can think of like:

@KafkaListener(topics = {"A" , "B"})

Or:

@KafkaListener(topics = "A")
public void receive() {}

@KafkaListener(topics = "B")
public void receive() {}

Both don't guarantee the sequence of reading.

How can I enforce my program to read topic A first, and only go to topic B after finishing the latest updates on topic A?

Upvotes: 0

Views: 1043

Answers (1)

Gary Russell
Gary Russell

Reputation: 174769

Use something like this...

@KafkaListener(id = "bReceiver", autoStartup = "false, topics = "B")
public void receive() {}

Set the idleEventInterval and add

@Autowired
KafkaListenerEndpointRegistry registry;

@EventListener(condition = "event.listenerId == 'aReceiver`)
public void eventListener(ListenerContainerIdleEvent event) {
    this.registry.getListenerContainer("aReceiver").stop(() -> { });
    this.registry.getListenerContainer("bReceiver").start();
}

Upvotes: 1

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