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Apache Kafka: MultiThreaded High Level Consumer

By Dinesh
Below code depicts an example of multi-threaded high level api consumer:

package learning.kafka;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import kafka.consumer.Consumer;
import kafka.consumer.ConsumerConfig;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;
import kafka.message.MessageAndMetadata;

public class MultiThreadHLConsumer {

       private ExecutorService executorService;
       private final ConsumerConnector consumer;
       private final String topic;

       public MultiThreadHLConsumer(String topicName) {
              Properties props = new Properties();
              props.put("zookeeper.connect", "192.168.56.101:2181");
              props.put("group.id", "testgroup");
              props.put("zookeeper.session.timeout.ms", "500");
              props.put("zookeeper.sync.time.ms", "250");
              props.put("auto.commit.interval.ms", "1000");

              ConsumerConfig config = new ConsumerConfig(props);

              consumer = Consumer.createJavaConsumerConnector(config);
              topic = topicName;
       }

       public void shutdown() throws InterruptedException {
              if (consumer != null)
                     consumer.shutdown();

              if (executorService != null){
                     executorService.shutdown();
                     executorService.awaitTermination(10000, TimeUnit.MILLISECONDS);
              }
       }

       private void testMultiThreadConsumer(int threadCount) {
              Map<String, Integer> topicMap = new HashMap<String, Integer>();

              topicMap.put(topic, new Integer(threadCount));

              Map<String, List<KafkaStream<byte[], byte[]>>> consumerStreamsMap = consumer
                           .createMessageStreams(topicMap);

              List<KafkaStream<byte[], byte[]>> streamList = consumerStreamsMap
                           .get(topic);

              executorService = Executors.newFixedThreadPool(threadCount);

              int count = 0;

              for (final KafkaStream sL : streamList) {
                     final int threadNumber = count;
                     executorService.submit(new Runnable() {

                           @Override
                           public void run() {
                                  try {
                                         ConsumerIterator<byte[], byte[]> conumeItr = sL.iterator();
                                         while (conumeItr.hasNext()) {
                                                MessageAndMetadata out =conumeItr.next();
                                                System.out.print("---:Partition:"+out.partition()+"---");
                                                System.out.println("Thread Number " + threadNumber
                                                              + ": "
                                                              + new String((byte[])out.message()));
                                               
                                         }
                                         System.out.println("Shutting down Thread Number: "
                                                       + threadNumber);
                                  } catch (Exception e) {
                                         e.printStackTrace();
                                  }
                           }
                     });
                     count++;
              }

       }

       public static void main(String[] args) throws InterruptedException {
              MultiThreadHLConsumer consumer = new MultiThreadHLConsumer("replicated-kafkatopic");
              consumer.testMultiThreadConsumer(10);
              System.out.println("........");
              java.util.Scanner s= new java.util.Scanner(System.in);
              while(!s.next().equals("yes")){
                     //wait              
              }
              consumer.shutdown();
              System.out.println("DS:End");
       }
}


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