kafka发送消息分区策略详解_kafka 分区后没起作用,消息还是存储到了某一个分区

背景：

     一个简单的用scala往kafka里写数据demo,每次运行只往一个分区写入数据，下次运行又选另一个分区一直写入。

发送例子：

 def main(args: Array[String]): Unit = {
    val topic = "test02"
    val brokers = "demo169.test.com:6667,demo167.test.com:6667,demo168.test.com:6667"
    val props = new Properties()
    props.put("metadata.broker.list", brokers)
    props.put("serializer.class", "kafka.serializer.StringEncoder")
    props.put("request.required.acks", "1")
 
    val kafkaConfig = new ProducerConfig(props)
    val producer = new Producer[String, String](kafkaConfig)
 
    while(true) {
      // prepare event data
      val event = new JSONObject()
      event
        .put("uid", getUserID)
        .put("event_time", System.currentTimeMillis.toString)
        .put("os_type", "Android")
        .put("click_count", click)
 
      // produce event message
     // producer.send(new KeyedMessage[String, String](topic,getUserID, event.toString))
      producer.send(new KeyedMessage[String, String](topic, event.toString))
      println("Message sent: " + event)
      Thread.sleep(1000)
    }
  }

原因探索:

 KeyedMessage有两种实例化方式导致：

def this(topic: String, message: V) = this(topic, null.asInstanceOf[K], null, message)

def this(topic: