CODEWITHSUNDEEP
spring-bootapache-kafkaspring-kafka
Szymon Zasada
Szymon Zasada

Reputation: 11

Spring Boot 3.3.3 Kafka Virtual Threads with custom Configuration

With Spring Boot 3.3.3 (spring.threads.virtual.enabled=true), the default Kafka autoconfiguration uses virtual threads. However, my custom Kafka bean configuration still uses platform threads. Could someone share a working example of how to configure a Kafka listener to use virtual threads? Specifically, I'm looking for configuration examples for:

@Bean
public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory(
        ConsumerFactory<String, String> consumerFactory) {
    // How to configure this to use virtual threads?
}

Upvotes: 1

Views: 68

Answers (1)

Artem Bilan
Artem Bilan

Reputation: 121542

So, if you have your own kafkaListenerContainerFactory, then Spring Boot's one is not going to be auto-configured:

@Bean
@ConditionalOnMissingBean(
    name = {"kafkaListenerContainerFactory"}
)
ConcurrentKafkaListenerContainerFactory<?, ?> kafkaListenerContainerFactory(

To enable virtual threads on your custom container factory, you have to modify its bean like this:

@Bean
public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory(
        ConsumerFactory<String, String> consumerFactory) {
        ConcurrentKafkaListenerContainerFactory<Object, Object> factory = new ConcurrentKafkaListenerContainerFactory();
        ...
        SimpleAsyncTaskExecutor executor = new SimpleAsyncTaskExecutor("kafka-");
        executor.setVirtualThreads(true);
        factory.getContainerProperties().setListenerTaskExecutor(executor);
}

This mimics what is there in Spring Boot auto-configuration.

NOTE: Apache Kafka uses new Thread() internally a lot, so assigning virtual threads for the listener container might not help too much.

Upvotes: 0

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