spark源码--worker启动原理和源码

worker启动一般包含两大部分：DriverRunner和ExcetorRunner。

worker启动driver的几个基本原理，最核心的是。worker内部会启动一个线程，这个线程可以理解为driverRunner。然后DriverRunner会去负责启动driver进程，并在之后对driver进程进行管理。

worker的启动步骤：

1- master要求worker启动driver和Excetor、launchDriver‘launchExcetor。

2- worker在内部launchDriver启动了一个线程DriverRunner；创建driver的工作目录； 封装启动driver的命令，用processBuilder启动Driver。

3- worker在内部通过LaunchExector启动一个ExectorRunner；创建Excetor的工作目录，封装启动Excetor的命令，用ProcessBuilder启动Excetor。

4- Excetor找到对应的driver，去反向注册自己。

LaunchDriver源码如下：

    case LaunchDriver(driverId, driverDesc) =>
      logInfo(s"Asked to launch driver $driverId")
      val driver = new DriverRunner(
        conf,
        driverId,
        workDir,
        sparkHome,
        driverDesc.copy(command = Worker.maybeUpdateSSLSettings(driverDesc.command, conf)),
        self,
        workerUri,
        securityMgr)
      drivers(driverId) = driver
      driver.start()

      coresUsed += driverDesc.cores
      memoryUsed += driverDesc.mem

    case KillDriver(driverId) =>
      logInfo(s"Asked to kill driver $driverId")
      drivers.get(driverId) match {
        case Some(runner) =>
          runner.kill()
        case None =>
          logError(s"Asked to kill unknown driver $driverId")
      }

    case driverStateChanged @ DriverStateChanged(driverId, state, exception) =>
      handleDriverStateChanged(driverStateChanged)

    case ReregisterWithMaster =>
      reregisterWithMaster()

    case ApplicationFinished(id) =>
      finishedApps += id
      maybeCleanupApplication(id)
  }

LaunchExecutor的源码如下：

 case LaunchExecutor(masterUrl, appId, execId, appDesc, cores_, memory_) =>
      if (masterUrl != activeMasterUrl) {
        logWarning("Invalid Master (" + masterUrl + ") attempted to launch executor.")
      } else {
        try {
          logInfo("Asked to launch executor %s/%d for %s".format(appId, execId, appDesc.name))

          // Create the executor's working directory
          val executorDir = new File(workDir, appId + "/" + execId)
          if (!executorDir.mkdirs()) {
            throw new IOException("Failed to create directory " + executorDir)
          }

          // Create local dirs for the executor. These are passed to the executor via the
          // SPARK_EXECUTOR_DIRS environment variable, and deleted by the Worker when the
          // application finishes.
          val appLocalDirs = appDirectories.getOrElse(appId, {
            val localRootDirs = Utils.getOrCreateLocalRootDirs(conf)
            val dirs = localRootDirs.flatMap { dir =>
              try {
                val appDir = Utils.createDirectory(dir, namePrefix = "executor")
                Utils.chmod700(appDir)
                Some(appDir.getAbsolutePath())
              } catch {
                case e: IOException =>
                  logWarning(s"${e.getMessage}. Ignoring this directory.")
                  None
              }
            }.toSeq
            if (dirs.isEmpty) {
              throw new IOException("No subfolder can be created in " +
                s"${localRootDirs.mkString(",")}.")
            }
            dirs
          })
          appDirectories(appId) = appLocalDirs
          val manager = new ExecutorRunner(
            appId,
            execId,
            appDesc.copy(command = Worker.maybeUpdateSSLSettings(appDesc.command, conf)),
            cores_,
            memory_,
            self,
            workerId,
            host,
            webUi.boundPort,
            publicAddress,
            sparkHome,
            executorDir,
            workerUri,
            conf,
            appLocalDirs, ExecutorState.RUNNING)
          executors(appId + "/" + execId) = manager
          manager.start()
          coresUsed += cores_
          memoryUsed += memory_
          sendToMaster(ExecutorStateChanged(appId, execId, manager.state, None, None))
        } catch {
          case e: Exception =>
            logError(s"Failed to launch executor $appId/$execId for ${appDesc.name}.", e)
            if (executors.contains(appId + "/" + execId)) {
              executors(appId + "/" + execId).kill()
              executors -= appId + "/" + execId
            }
            sendToMaster(ExecutorStateChanged(appId, execId, ExecutorState.FAILED,
              Some(e.toString), None))
        }
      }

拓展：中华石杉--spark从入门到精通-第49讲