yarnCluster运行源码(3)

上一阶段   在nm上运行了  CoarseGrainedExecutorBackend （消息通讯体），其实就是和dirver的

CoarseGrainedSchedulerBackend 来通讯的

CoarseGrainedExecutorBackend 的main方法

run(driverUrl, executorId, hostname, cores, appId, workerUrl, userClassPath)

CoarseGrainedExecutorBackend的run方法就是准备了 配置和环境

它是一个endpoint  

关注onstart方法

 override def onStart() {
    logInfo("Connecting to driver: " + driverUrl)
    rpcEnv.asyncSetupEndpointRefByURI(driverUrl).flatMap { ref =>
      // This is a very fast action so we can use "ThreadUtils.sameThread"
//获得driver的联系
      driver = Some(ref)
//向driver注册，可以到dirver的ScheduleBackEnd 的receive方法 case RegisterExecutor
      ref.ask[Boolean](RegisterExecutor(executorId, self, hostname, cores, extractLogUrls))
    }(ThreadUtils.sameThread).onComplete {
      // This is a very fast action so we can use "ThreadUtils.sameThread"
      case Success(msg) =>
        // Always receive `true`. Just ignore it
      case Failure(e) =>
        exitExecutor(1, s"Cannot register with driver: $driverUrl", e, notifyDriver = false)
    }(ThreadUtils.sameThread)
  }

receive方法

override def receive: PartialFunction[Any, Unit] = {
//driver 注册注册成功
    case RegisteredExecutor =>
      logInfo("Successfully registered with driver")
      try {
//new一个 executor   是一个对象
        executor = new Executor(executorId, hostname, env, userClassPath, isLocal = false)
      } catch {
        case NonFatal(e) =>
          exitExecutor(1, "Unable to create executor due to " + e.getMessage, e)
      }

    case RegisterExecutorFailed(message) =>
      exitExecutor(1, "Slave registration failed: " + message)
//如果driver发送 launchTask 那么就反序列化 然后执行任务
    case LaunchTask(data) =>
      if (executor == null) {
        exitExecutor(1, "Received LaunchTask command but executor was null")
      } else {
        val taskDesc = ser.deserialize[TaskDescription](data.value)
        logInfo("Got assigned task " + taskDesc.taskId)
        executor.launchTask(this, taskId = taskDesc.taskId, attemptNumber = taskDesc.attemptNumber,
          taskDesc.name, taskDesc.serializedTask)
      }

    case KillTask(taskId, _, interruptThread) =>
      if (executor == null) {
        exitExecutor(1, "Received KillTask command but executor was null")
      } else {
        executor.killTask(taskId, interruptThread)
      }

    case StopExecutor =>
      stopping.set(true)
      logInfo("Driver commanded a shutdown")
      // Cannot shutdown here because an ack may need to be sent back to the caller. So send
      // a message to self to actually do the shutdown.
      self.send(Shutdown)

    case Shutdown =>
      stopping.set(true)
      new Thread("CoarseGrainedExecutorBackend-stop-executor") {
        override def run(): Unit = {
          // executor.stop() will call `SparkEnv.stop()` which waits until RpcEnv stops totally.
          // However, if `executor.stop()` runs in some thread of RpcEnv, RpcEnv won't be able to
          // stop until `executor.stop()` returns, which becomes a dead-lock (See SPARK-14180).
          // Therefore, we put this line in a new thread.
          executor.stop()
        }
      }.start()
  }