Kafka Java 消费者从未收到任何消息

我正在尝试设置一个基本的 Java 消费者来接收来自 Kafka 主题的消息。我已经跟踪了样本 -https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example https://cwiki.apache.org/confluence/display/KAFKA/Consumer+Group+Example- 并且有这个代码：

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 正在相关 EC2 主机上运行，​​我可以使用 kafka-console- Producer.sh 和 kafka-console-consumer.sh 工具发送和接收有关主题“test”的消息。端口 2181 是开放的，可以从运行消费者的机器上使用（9092 也是如此，但这似乎也没有帮助）。

不幸的是，当我运行这个时，我从未在我的消费者中收到任何消息。既没有关于该主题的现有消息，也没有在消费者运行时使用 kafka-console- Producer.sh 发送的新发送的消息。

这是使用在 CentOS 6.4 x64 上运行的 Kafka 0.8.1.1，使用 OpenJDK 1.7.0_65。

编辑：FWIW，当消费者程序启动时，我看到这个 Zookeeper 输出：

[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)

知道这会发生什么吗？非常感谢任何和所有的帮助。

我自己为后代回答这个问题，以防其他人遇到类似的问题。

问题是这样的：Kafka 代理和 Zookeeper 位于 EC2 节点上，而消费者则在我本地运行的笔记本电脑上。连接到 Zookeeper 时，客户端会收到对“ip-10-0-x-x.ec2.internal”的引用，该引用不会（默认情况下）从 EC2 外部解析。当我在客户端上正确配置 log4j 并获取所有日志消息后，这一点就变得很清楚了。

解决方法是在我的 /etc/hosts 文件中添加一个条目，将 ec2 内部主机名映射到公共可路由 IP 地址。