【原】 Spark中Worker源码分析（二）

继续前一篇的内容。前一篇内容为：
Spark中Worker源码分析（一）http://www.cnblogs.com/yourarebest/p/5300202.html

4.receive方法，
receive方法主要分为以下14种情况：

（1）worker向master注册成功后，详见代码
（2）worker向master发送心跳消息，如果还没有注册到master上，该消息将被忽略，详见代码
（3）worker的工作空间的清理，详见代码
（4）更换master，详见代码
（5）worker注册失败，详见代码
（6）再次连接worker，详见代码
（7）创建executor，详见代码
（8）executor的转态发生改变时，详见代码
（9）kill executor，详见代码
（10）创建driver，详见代码
（11）kill driver，详见代码
（12）driver的状态发生变化时，详见代码
（13）将worker注册到master上，详见代码
（14）app执行完毕，详见代码
worker与master相关的交互为（1）（2）（4）（6）（13）
worker与driver相关的交互为（10）（11）（12）
worker与executor相关的交互为（3）（7）（8）（9）（14），需要说明的是（3）（14）它们的完成都与executor有着密切的联系。

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<code>
override def receive: PartialFunction[Any, Unit] = {
    //(1)注册成功的Woker
    case RegisteredWorker(masterRef, masterWebUiUrl) =>
      logInfo("Successfully registered with master " + masterRef.address.toSparkURL)
      registered = true
      changeMaster(masterRef, masterWebUiUrl)
      //守护线程15s发送一次心跳消息
      forwordMessageScheduler.scheduleAtFixedRate(new Runnable {
        override def run(): Unit = Utils.tryLogNonFatalError {
          self.send(SendHeartbeat)
        }
      }, 0, HEARTBEAT_MILLIS, TimeUnit.MILLISECONDS)
      //如果允许清理
      if (CLEANUP_ENABLED) {
        logInfo(s"Worker cleanup enabled; old application directories will be deleted in: $workDir")
        forwordMessageScheduler.scheduleAtFixedRate(new Runnable {
          override def run(): Unit = Utils.tryLogNonFatalError {
            //守护线程30min清理app文件夹
            self.send(WorkDirCleanup)
          }
        }, CLEANUP_INTERVAL_MILLIS, CLEANUP_INTERVAL_MILLIS, TimeUnit.MILLISECONDS)
      }
    //（2）worker向master发送心跳消息，如果还没有注册到master上，该消息将被忽略
    case SendHeartbeat =>
      if (connected) { sendToMaster(Heartbeat(workerId, self)) }
    //（3）worker的工作空间的清理
    case WorkDirCleanup =>
         //为了加快独立将来独立线程的清理工作，不要占用worker rpcEndpoint的端口号，拷贝ids所以它可以被清理线程使用
      val appIds = executors.values.map(_.appId).toSet
      val cleanupFuture = concurrent.future {
        val appDirs = workDir.listFiles()
        if (appDirs == null) {
          throw new IOException("ERROR: Failed to list files in " + appDirs)
        }
        appDirs.filter { dir =>
          //目录正在被app使用-当清理时检查app是否在运行
          val appIdFromDir = dir.getName
          val isAppStillRunning = appIds.contains(appIdFromDir)
          dir.isDirectory && !isAppStillRunning &&
          !Utils.doesDirectoryContainAnyNewFiles(dir, APP_DATA_RETENTION_SECONDS)
        }.foreach { dir =>
          logInfo(s"Removing directory: ${dir.getPath}")
          Utils.deleteRecursively(dir)
        }
      }(cleanupThreadExecutor)
      cleanupFuture.onFailure {
        case e: Throwable =>
          logError("App dir cleanup failed: " + e.getMessage, e)
      }(cleanupThreadExecutor)
    //（4）更换master
    case MasterChanged(masterRef, masterWebUiUrl) =>
      logInfo("Master has changed, new master is at " + masterRef.address.toSparkURL)
      changeMaster(masterRef, masterWebUiUrl)
      val execs = executors.values.
        map(e => new ExecutorDescription(e.appId, e.execId, e.cores, e.state))
      masterRef.send(WorkerSchedulerStateResponse(workerId, execs.toList, drivers.keys.toSeq))
    //（5）worker注册失败
    case RegisterWorkerFailed(message) =>
      if (!registered) {
        logError("Worker registration failed: " + message)
        System.exit(1)
      }
    //（6）再次连接Worker
    case ReconnectWorker(masterUrl) =>
      logInfo(s"Master with url $masterUrl requested this worker to reconnect.")
      //再次将worker注册到masters上
      registerWithMaster()
    //（7）创建Executor
    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))
          //创建executor的工作目录
          val executorDir = new File(workDir, appId + "/" + execId)
          if (!executorDir.mkdirs()) {
            throw new IOException("Failed to create directory " + executorDir)
          }
          //为executors创建本地目录，通过SPARK_EXECUTOR_DIRS环境变量设置，当app执行完后并删除
          val appLocalDirs = appDirectories.get(appId).getOrElse {
            Utils.getOrCreateLocalRootDirs(conf).map { dir =>
              val appDir = Utils.createDirectory(dir, namePrefix = "executor")
              Utils.chmod700(appDir)
              appDir.getAbsolutePath()
            }.toSeq
          }
          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.LOADING)
          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))
          }
        }
      }
    //（8）executor的转态发生改变时
    case executorStateChanged @ ExecutorStateChanged(appId, execId, state, message, exitStatus) =>
      handleExecutorStateChanged(executorStateChanged)
    //（9）kill executor
    case KillExecutor(masterUrl, appId, execId) =>
      if (masterUrl != activeMasterUrl) {
        logWarning("Invalid Master (" + masterUrl + ") attempted to launch executor " + execId)
      } else {
        val fullId = appId + "/" + execId
        executors.get(fullId) match {
          case Some(executor) =>
            logInfo("Asked to kill executor " + fullId)
            executor.kill()
          case None =>
            logInfo("Asked to kill unknown executor " + fullId)
        }
      }
    //（10）创建Driver
    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
    }
    //（11）kill Driver
    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")
      }
    }
    //（12）driver的状态发生变化时
    case driverStateChanged @ DriverStateChanged(driverId, state, exception) => {
      handleDriverStateChanged(driverStateChanged)
    }
    //（13）将worker注册到master上
    case ReregisterWithMaster =>
      reregisterWithMaster()
    //（14）app执行完毕
    case ApplicationFinished(id) =>
      finishedApps += id
      //删除执行完的app在执行过程中创建的本地文件
      maybeCleanupApplication(id)
  }
</code>

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