Standalone client模式下的提交spark程序

standalone client模式下，使用ClientApp提交spark程序。

此類在deploy/Client.scala文件中。

private[spark] class ClientApp extends SparkApplication {
  override def start(args: Array[String], conf: SparkConf): Unit = {
    val driverArgs = new ClientArguments(args)
    val rpcEnv =
      RpcEnv.create("driverClient", Utils.localHostName(), 0, conf, new SecurityManager(conf))
    val masterEndpoints = driverArgs.masters.map(RpcAddress.fromSparkURL).
      map(rpcEnv.setupEndpointRef(_, Master.ENDPOINT_NAME))
    rpcEnv.setupEndpoint("client", new ClientEndpoint(rpcEnv, driverArgs, masterEndpoints, conf))
    rpcEnv.awaitTermination()
  }
}

代碼很簡單。start方法就是建立一個ClientEndpoint，而後與Master交互。

ClientEndpoint的主要功能和方法：

override def onStart(): Unit = {
    driverArgs.cmd match {
      case "launch" =>
        // TODO: We could add an env variable here and intercept it in `sc.addJar` that would
        //       truncate filesystem paths similar to what YARN does. For now, we just require
        //       people call `addJar` assuming the jar is in the same directory.
        val mainClass = "org.apache.spark.deploy.worker.DriverWrapper"

        val classPathConf = config.DRIVER_CLASS_PATH.key
        val classPathEntries = getProperty(classPathConf, conf).toSeq.flatMap { cp =>
          cp.split(java.io.File.pathSeparator)
        }

        val libraryPathConf = config.DRIVER_LIBRARY_PATH.key
        val libraryPathEntries = getProperty(libraryPathConf, conf).toSeq.flatMap { cp =>
          cp.split(java.io.File.pathSeparator)
        }

        val extraJavaOptsConf = config.DRIVER_JAVA_OPTIONS.key
        val extraJavaOpts = getProperty(extraJavaOptsConf, conf)
          .map(Utils.splitCommandString).getOrElse(Seq.empty)

        val sparkJavaOpts = Utils.sparkJavaOpts(conf)
        val javaOpts = sparkJavaOpts ++ extraJavaOpts
        val command = new Command(mainClass,
          Seq("{{WORKER_URL}}", "{{USER_JAR}}", driverArgs.mainClass) ++ driverArgs.driverOptions,
          sys.env, classPathEntries, libraryPathEntries, javaOpts)
        val driverResourceReqs = ResourceUtils.parseResourceRequirements(conf,
          config.SPARK_DRIVER_PREFIX)
        val driverDescription = new DriverDescription(
          driverArgs.jarUrl,
          driverArgs.memory,
          driverArgs.cores,
          driverArgs.supervise,
          command,
          driverResourceReqs)
        asyncSendToMasterAndForwardReply[SubmitDriverResponse](
          RequestSubmitDriver(driverDescription))

      case "kill" =>
        val driverId = driverArgs.driverId
        asyncSendToMasterAndForwardReply[KillDriverResponse](RequestKillDriver(driverId))
    }

封裝一個org.apache.spark.deploy.worker.DriverWrapper類，而後將DriverDescription消息發送給Master，在Master上啓動這個DriverWrapper。DriverWrapper很簡單了，這裏就不細說了，做用就是起一個線程，執行咱們的spark程序的main方法。