I have a Spring Boot application and it needs to process some Kafka streaming data. I added an infinite loop to a
CommandLineRunner
class that will run on startup. In there is a Kafka consumer that can be woken up. I added a shutdown hook with Runtime.getRuntime().addShutdownHook(new Thread(consumer::wakeup));
. Will I run into any problems? Is there a more idiomatic way of doing this in Spring? Should I use @Scheduled
instead? The code below is stripped of specific Kafka-implementation stuff but otherwise complete.import org.apache.kafka.clients.consumer.Consumer;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.errors.WakeupException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
import java.time.Duration;
import java.util.Properties;
@Component
public class InfiniteLoopStarter implements CommandLineRunner {
private final Logger logger = LoggerFactory.getLogger(this.getClass());
@Override
public void run(String... args) {
Consumer<AccountKey, Account> consumer = new KafkaConsumer<>(new Properties());
Runtime.getRuntime().addShutdownHook(new Thread(consumer::wakeup));
try {
while (true) {
ConsumerRecords<AccountKey, Account> records = consumer.poll(Duration.ofSeconds(10L));
//process records
}
} catch (WakeupException e) {
logger.info("Consumer woken up for exiting.");
} finally {
consumer.close();
logger.info("Closed consumer, exiting.");
}
}
}
--------------------------------------
You'll need the following dependency:
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka</artifactId>
<version>2.2.2.RELEASE</version>
</dependency>
Configuration is as easy adding the @EnableKafka
annotation to a config class and then setting up Listener and ConsumerFactory beans
Once configured you can setup a consumer easily as follows:
@KafkaListener(topics = "topicName")
public void listenWithHeaders(
@Payload String message,
@Header(KafkaHeaders.RECEIVED_PARTITION_ID) int partition) {
System.out.println("Received Message: " + message"+ "from partition: " + partition);
}
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