Question

I need the consumer to read messages from the topic not immediately, but after a certain time interval. In my case, this time = 10 seconds.

I made a KafkaConfig in which I specified the properties and added them to the DefaultKafkaConsumerFactory:

I tried through

factory.getContainerProperties().setIdleBetweenPolls(10000);
I also tried via

props.put(ConsumerConfig.MAX_POLL_INTERVAL_MS_CONFIG, 10000);
I also tried via

props.put(ConsumerConfig.FETCH_MIN_BYTES_CONFIG, "999999999"); props.put(ConsumerConfig.FETCH_MAX_WAIT_MS_CONFIG, "10000")

But none of the above works :(

I am sad.

I found similar cases here, they are very similar to my solution from the internet, but they don t work either.

Example of my code below:

@Slf4j
@EnableKafka
@Configuration
@ConditionalOnProperty(
    value = "exclude.kafka",
    havingValue = "false",
    matchIfMissing = true
)
@RequiredArgsConstructor
public class MyKafkaConfig {

    @Bean
    public ConcurrentKafkaListenerContainerFactory<String, String> concurrentKafkaListenerContainerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<>();
        factory.setConsumerFactory(consumerFactory());

        factory.getContainerProperties().setIdleBetweenPolls(10000);

        return factory;
    }

    private ConsumerFactory<String, String> consumerFactory() {
        return new DefaultKafkaConsumerFactory<>(consumerConfig());
    }

    private Map<String, Object> consumerConfig() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "batchId");
//        props.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, "500");
//        props.put(ConsumerConfig.MAX_POLL_INTERVAL_MS_CONFIG, 10000);
        props.put(ConsumerConfig.FETCH_MIN_BYTES_CONFIG, "999999999");
//        props.put(ConsumerConfig.FETCH_MAX_WAIT_MS_CONFIG, "10000");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        return props;
    }
}

Does anyone have any ideas how to make Kafka work (read messages after 10 seconds, not as soon as they hit the topic) ?

Answer 1

There is no built in message delay - see more about this here.

You can however, leverage the pause and resume methods from the KafkaConsumer API

Which states the following

Kafka supports dynamic controlling of consumption flows by using pause(Collection) and resume(Collection) to pause the consumption on the specified assigned partitions and resume the consumption on the specified paused partitions respectively in the future poll(long) calls.

This seem to me as the go to solution after reading this

So Java code would be as following, more or less, this is a sketch:

Set<TopicPartition> partitions = consumer.assignment();
consumer.pause(partitions);
Thread.sleep(10000); // 10 Seconds in millis
...
consumer.resume(partitions)

Disclaimer: I haven t tested it.

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