我正在使用 Kafka 0.8.0 并尝试实现下面提到的场景。

JCA API(充当生产者并将数据发送到)-----> 消费者------> HBase

我在使用 JCA 客户端获取数据后立即将每条消息发送给消费者。例如，一旦生产者发送消息 1 ，我想从消费者那里获取相同的消息并将其“放入” HBase 中。但是我的消费者在一些随机的 n 条消息之后开始获取消息。我想让生产者和消费者同步，以便他们都开始一起工作。

我用过:

1 经纪人

1 个主题

1 个单一生产者和高级消费者

谁能建议我需要做什么才能达到同样的效果？

编辑:

添加一些相关的代码片段。

消费者.java

public class Consumer extends Thread {
    private final ConsumerConnector consumer;
    private final String topic;
    PrintWriter pw = null;
    int t = 0;
    StringDecoder kd = new StringDecoder(null);
    Map<String, Integer> topicCountMap = new HashMap<String, Integer>();
    Map<String, List<KafkaStream<String, Signal>>> consumerMap;
    KafkaStream<String, Signal> stream;
    ConsumerIterator<String, Signal> it;

    public Consumer(String topic) {
        consumer = kafka.consumer.Consumer.createJavaConsumerConnector(createConsumerConfig());

        this.topic = topic;
        topicCountMap.put(topic, new Integer(1));
        consumerMap = consumer.createMessageStreams(topicCountMap, kd, new Serializer(
                new VerifiableProperties()));
        stream = consumerMap.get(topic).get(0);
        it = stream.iterator();

    }

    private static ConsumerConfig createConsumerConfig() {
        Properties props = new Properties();
        props.put("zookeeper.connect", KafkaProperties.zkConnect);
        props.put("group.id", KafkaProperties.groupId);
        props.put("zookeeper.session.timeout.ms", "400");
        props.put("zookeeper.sync.time.ms", "200");
        props.put("auto.commit.interval.ms", "1000");
        props.put("fetch.size", "1024");

        return new ConsumerConfig(props);

    }

    synchronized public void run() {

        while (it.hasNext()) {
            t = (it.next().message()).getChannelid();
            System.out.println("In Consumer received msg" + t);
        }
    }
}

producer.java

public class Producer {
    public final kafka.javaapi.producer.Producer<String, Signal> producer;
    private final String topic;
    private final Properties props = new Properties();

    public Producer(String topic)
    {
        props.put("serializer.class", "org.bigdata.kafka.Serializer");
        props.put("key.serializer.class", "kafka.serializer.StringEncoder");
        props.put("metadata.broker.list", "localhost:9092");
        // Use random partitioner. Don't need the key type. Just set it to Integer.
        // The message is of type userdefined Object .
        producer = new kafka.javaapi.producer.Producer<String,Signal(newProducerConfig(props));
        this.topic = topic;
    }
}

KafkaProperties.java

public interface KafkaProperties {
    final static String zkConnect = "127.0.0.1:2181";
    final static String groupId = "group1";
    final static String topic = "test00";
    final static String kafkaServerURL = "localhost";
    final static int kafkaServerPort = 9092;
    final static int kafkaProducerBufferSize = 64 * 1024;
    final static int connectionTimeOut = 100000;
    final static int reconnectInterval = 10000;
    final static String clientId = "SimpleConsumerDemoClient";
}

这就是消费者在前 10 条消息中的行为方式，它没有系统化消费者收到的那条消息，但从第 11 条消息开始，它开始正常运行。

     producer sending msg1

     producer sending msg2

     producer sending msg3

     producer sending msg4

     producer sending msg5

     producer sending msg6

     producer sending msg7

     producer sending msg8

     producer sending msg9

     producer sending msg10

     producer sending msg11

     producer sending msg12
     In Consumer received msg12

     producer sending msg13
     In Consumer received msg13

     producer sending msg14
     In Consumer received msg14

     producer sending msg15
     In Consumer received msg15

     producer sending msg16
     In Consumer received msg16

     producer sending msg17
     In Consumer received msg17

     producer sending msg18
     In Consumer received msg18

     producer sending msg19
     In Consumer received msg19

     producer sending msg20
     In Consumer received msg20

     producer sending msg21
     In Consumer received msg21

已编辑:添加生产者向消费者发送消息的监听器功能。而且我使用的是默认的生产者配置，没有覆盖它

public synchronized void onValueChanged(final MonitorEvent event_) {


    // Get the value from the DBR
    try {
        final DBR dbr = event_.getDBR();

        final String[] val = (String[]) dbr.getValue();

        producer1.producer.send(new KeyedMessage<String, Signal>         
                    (KafkaProperties.topic,new Signal(messageNo)));
        System.out.println("producer sending msg"+messageNo);

        messageNo++;


    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

最佳答案

1. 尝试将 props.put("request.required.acks", "1") 添加到生产者配置中。默认情况下，生产者不等待确认，并且不保证消息传递。因此，如果您在测试之前启动代理，生产者可能会在代理完全初始化之前开始发送消息，并且前几条消息可能会丢失。

2. 尝试将 props.put("auto.offset.reset", "smallest") 添加到消费者配置中。相当于kafka-console-consumer.sh的--from-beginning选项。如果您的消费者启动时间晚于生产者并且 Zookeeper 中没有保存偏移量数据，则默认情况下它将仅开始消费新消息(请参阅文档中的 Consumer configs)。

关于java - 消费者在 Apache Kafka 中消费消息的延迟，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21727150/