Kafka Architecture

Kafka 主函数在kafka.Kafka.scala 如下：

      val serverConfig = new KafkaConfig(props)
      KafkaMetricsReporter.startReporters(serverConfig.props)
      val kafkaServerStartble = new KafkaServerStartable(serverConfig)
      
      kafkaServerStartble.startup

读取命令行中第一个参数作为配置文件

bin/zookeeper-server-start.sh config/zookeeper.properties

kafka.utils.Utils从中读取配置项 生成props 作为KafkaConfig参数

KafkaConfig构造函数还是已VerifiableProperties作为参数

KafkaMetricsReporter调用startReporters(props) 

class KafkaServerStartable(val serverConfig: KafkaConfig) extends Logging {
  private var server: KafkaServer = null

  def startup() {
      server.startup()
  }
}

KafkaServerStartable看上去就是一个KafkaServer ……  直接看kafka.server.KafkaServer吧

    /* start scheduler */
    kafkaScheduler.startup()

    /* setup zookeeper */
    zkClient = initZk()

    /* start log manager */
    logManager = createLogManager(zkClient)
    logManager.startup()

    socketServer = new SocketServer(config.brokerId,
      config.hostName,
      config.port,
      config.numNetworkThreads,
      config.queuedMaxRequests,
      config.socketSendBufferBytes,
      config.socketReceiveBufferBytes,
      config.socketRequestMaxBytes)
    socketServer.startup()

    replicaManager = new ReplicaManager(config, 
      time, 
      zkClient, 
      kafkaScheduler, 
      logManager, 
      isShuttingDown)
    kafkaController = new KafkaController(config, zkClient)

    /* start processing requests */
    apis = new KafkaApis(socketServer.requestChannel, 
      replicaManager, 
      zkClient, 
      config.brokerId, 
      config, kafkaController)
      
    requestHandlerPool = new KafkaRequestHandlerPool(config.brokerId, 
      socketServer.requestChannel, 
      apis, 
      config.numIoThreads)

    Mx4jLoader.maybeLoad()
    replicaManager.startup()
    kafkaController.startup()

    topicConfigManager = new TopicConfigManager(zkClient, logManager)
    topicConfigManager.startup()

    /* tell everyone we are alive */
    kafkaHealthcheck = new KafkaHealthcheck(config.brokerId, 
      config.advertisedHostName, 
      config.advertisedPort, 
      config.zkSessionTimeoutMs, 
      zkClient)
      
    kafkaHealthcheck.startup()

    registerStats()
    startupComplete.set(true);

读kafka源码到了这里，突然间有一种豁然开朗的感觉，

在这里先后启动了

KafkaScheduler、LogManager、SocketServer、ReplicaManager、KakfaController、KafkaApi ....

好戏~ 就此上演 待我~ 细说从头