I'm trying to setup a basic Java consumer to receive messages from a Kafka topic. I've followed the sample at - https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example - and have this code:
package org.example.kafka.client;
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 kafka.consumer.ConsumerConfig;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;
public class KafkaClientMain
{
private final ConsumerConnector consumer;
private final String topic;
private ExecutorService executor;
public KafkaClientMain(String a_zookeeper, String a_groupId, String a_topic)
{
this.consumer = kafka.consumer.Consumer.createJavaConsumerConnector(
createConsumerConfig(a_zookeeper, a_groupId));
this.topic = a_topic;
}
private static ConsumerConfig createConsumerConfig(String a_zookeeper, String a_groupId) {
Properties props = new Properties();
props.put("zookeeper.connect", a_zookeeper);
props.put("group.id", a_groupId);
props.put("zookeeper.session.timeout.ms", "1000");
props.put("zookeeper.sync.time.ms", "1000");
props.put("auto.commit.interval.ms", "1000");
props.put("auto.offset.reset", "smallest");
return new ConsumerConfig(props);
}
public void shutdown() {
if (consumer != null) consumer.shutdown();
if (executor != null) executor.shutdown();
}
public void run(int a_numThreads) {
Map<String, Integer> topicCountMap = new HashMap<String, Integer>();
topicCountMap.put(topic, new Integer(a_numThreads));
Map<String, List<KafkaStream<byte[], byte[]>>> consumerMap = consumer.createMessageStreams(topicCountMap);
List<KafkaStream<byte[], byte[]>> streams = consumerMap.get(topic);
System.out.println( "streams.size = " + streams.size() );
// now launch all the threads
//
executor = Executors.newFixedThreadPool(a_numThreads);
// now create an object to consume the messages
//
int threadNumber = 0;
for (final KafkaStream stream : streams) {
executor.submit(new ConsumerTest(stream, threadNumber));
threadNumber++;
}
}
public static void main(String[] args)
{
String zooKeeper = "ec2-whatever.compute-1.amazonaws.com:2181";
String groupId = "group1";
String topic = "test";
int threads = 1;
KafkaClientMain example = new KafkaClientMain(zooKeeper, groupId, topic);
example.run(threads);
}
}
and
package org.example.kafka.client;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
public class ConsumerTest implements Runnable
{
private KafkaStream m_stream;
private int m_threadNumber;
public ConsumerTest(KafkaStream a_stream, int a_threadNumber)
{
m_threadNumber = a_threadNumber;
m_stream = a_stream;
}
public void run()
{
System.out.println( "calling ConsumerTest.run()" );
ConsumerIterator<byte[], byte[]> it = m_stream.iterator();
while (it.hasNext())
{
System.out.println("Thread " + m_threadNumber + ": " + new String(it.next().message()));
}
System.out.println("Shutting down Thread: " + m_threadNumber);
}
}
Kafka is running on the EC2 host in question, and I can send and receive messages on the topic "test" using the kafka-console-producer.sh and kafka-console-consumer.sh tools. Port 2181 is open and available from the machine where the consumer is running (and so is 9092 for good measure, but that didn't seem to help either).
Unfortunately, I never receive any messages in my consumer when I run this. Neither existing messages on the topic, nor newly sent messages that I send using kafka-console-producer.sh, while the consumer is running.
This is using Kafka 0.8.1.1 running on CentOS 6.4 x64, using OpenJDK 1.7.0_65.
Edit: FWIW, when the consumer program starts, I see this Zookeeper output:
[2014-08-01 15:56:38,045] INFO Accepted socket connection from /98.101.159.194:24218 (org.apache.zookeeper.server.NIOServerCnxn)
[2014-08-01 15:56:38,049] INFO Client attempting to establish new session at /98.101.159.194:24218 (org.apache.zookeeper.server.NIOServerCnxn)
[2014-08-01 15:56:38,053] INFO Established session 0x1478e963fb30008 with negotiated timeout 6000 for client /98.101.159.194:24218 (org.apache.zookeeper.server.NIOServerCnxn)
Any idea what might be going on with this? Any and all help is much appreciated.