spark源码（二）Master recive方法

   Master recive全部方法

        一.case ElectedLeader => ......
        二.case CompleteRecovery => ......
        三.case RevokedLeadership => ......
        四.case WorkerDecommissioning => ......
        五.case DecommissionWorkers => ......
        六.case RegisterWorker => ......
        七.case RegisterApplication => ......
        八.case ExecutorStateChanged => ......
        九.case DriverStateChanged => ......
        十.case Heartbeat => ......
        十一.case MasterChangeAcknowledged => ......
        十二.case WorkerSchedulerStateResponse => ......
        十三.case WorkerLatestState => ......
        十四.case UnregisterApplication => ......
        十五.case CheckForWorkerTimeOut => ......

一.ElectedLeader 详解

    //下面这个方法，其实就是调用persistenceEngine 的方法的get属性 拿到driver，worker等信息
    //persistenceEngine的初始化是在onStart 方法上
    val (storedApps, storedDrivers, storedWorkers) = persistenceEngine.readPersistedData(rpcEnv)
    //如果driver和worker是空的，当前节点就是主节点，不是的化就是备份节点
    state = if (storedApps.isEmpty && storedDrivers.isEmpty && storedWorkers.isEmpty) {
        RecoveryState.ALIVE
    } else {
        RecoveryState.RECOVERING
    }
    logInfo("I have been elected leader! New state: " + state)
    if (state == RecoveryState.RECOVERING) {
        //开始主备切换的工作，下面详解
        beginRecovery(storedApps, storedDrivers, storedWorkers)
        //启动定时，定时给自己发送CompleteRecovery消息，CompleteRecovery下个详解
        recoveryCompletionTask = forwardMessageThread.schedule(new Runnable {
          override def run(): Unit = Utils.tryLogNonFatalError {
            self.send(CompleteRecovery)
          }
        }, workerTimeoutMs, TimeUnit.MILLISECONDS)
    }

1.1 start方法(zkFactory.createPersistenceEngine(), zkFactory.createLeaderElectionAgent(this)) 详解

    def createPersistenceEngine(): PersistenceEngine = {
        new ZooKeeperPersistenceEngine(conf, serializer)//再次往里走
    }

1.2 ZooKeeperPersistenceEngine 详解

    private[master] class ZooKeeperPersistenceEngine(conf: SparkConf, val serializer: Serializer)
        extends PersistenceEngine with Logging {

        private val workingDir = conf.get(ZOOKEEPER_DIRECTORY).getOrElse("/spark") + "/master_status"
        private val zk: CuratorFramework = SparkCuratorUtil.newClient(conf)

        SparkCuratorUtil.mkdir(zk, workingDir)
        //后面的方法其实全部是基于zk对象完成的，那总体来说就是读取了zk中的配置信息，来确定master
        .......
    }

1.3 beginRecovery(storedApps, storedDrivers, storedWorkers) 详解

    private def beginRecovery(storedApps: Seq[ApplicationInfo], storedDrivers: Seq[DriverInfo],
        storedWorkers: Seq[WorkerInfo]): Unit = {
        for (app <- storedApps) {
            logInfo("Trying to recover app: " + app.id)
            try {
                //把当前的不在addressToApp中的app都添加到现有变量中
                //apps，idToApp，endpointToApp，addressToApp，waitingApps  上面有详细的解释
                registerApplication(app)
                app.state = ApplicationState.UNKNOWN
                app.driver.send(MasterChanged(self, masterWebUiUrl))//后续解析driver的时候再看这个
            } catch {
                case e: Exception => logInfo("App " + app.id + " had exception on reconnect")
            }
        }

        for (driver <- storedDrivers) {//注册所有的driver
            drivers += driver
        }

        for (worker <- storedWorkers) {
            logInfo("Trying to recover worker: " + worker.id)
            try {
                //注册所有的worker到变量workers  idToWorker  addressToWorker里面
                //将所有的worker driver 全部移除
                registerWorker(worker)
                worker.state = WorkerState.UNKNOWN
                worker.endpoint.send(MasterChanged(self, masterWebUiUrl))
            } catch {
               se e: Exception => logInfo("Worker " + worker.id + " had exception on reconnect")
            }
        }
    }

1.3.1 beginRecovery 变量操作 详解

    当前Master 类初始化的时候，其实属性里面都没有值的。
    参数需要的(storedApps, storedDrivers, storedWorkers)也是从ZK里面拉取的，所以可以避免重复元素
    属性其实有很多都是hashset和hashmap,也可以避免重复

    函数里面操作了很多变量还有嵌套，但最后都是调用了 schedule() 方法，
    在这就列出来所有操作的变量和RPC请求
    操作的变量：
    registerApplication：
        applicationMetricsSystem.registerSource(app.appSource)
        apps += app
        idToApp(app.id) = app
        endpointToApp(app.driver) = app
        addressToApp(appAddress) = app
        waitingApps += app
    drivers += driver
    registerWorker：
        workers -= w
        workers += worker
        idToWorker(worker.id) = worker
        addressToWorker(workerAddress) = worker
    removeWorker：
        idToWorker -= worker.id
        addressToWorker -= worker.endpoint.address
    relaunchDriver：
        drivers.add(newDriver)
        waitingDrivers += newDriver
    removeDriver：
        drivers -= driver
        completedDrivers += driver
        driver.state = finalState
        driver.exception = exception
        driver.worker.foreach(w => w.removeDriver(driver))

    RPC请求：
        worker.send(MasterChanged())
        driver.send(MasterChanged())
        driver.send(ExecutorUpdated())
        driver.send(WorkerRemoved())

1.3.1.1 schedule() 详解

    //就是为一个application分配资源 其实这个方法 被调用了很多次
    private def schedule(): Unit = {
        if (state != RecoveryState.ALIVE) {//当前节点非活跃状态就退出
          return
        }
        val shuffledAliveWorkers = Random.shuffle(workers.toSeq.filter(_.state == WorkerState.ALIVE))
        val numWorkersAlive = shuffledAliveWorkers.size//找到所有还在活跃的worker
        var curPos = 0
        for (driver <- waitingDrivers.toList) {//循环所有worker
            var launched = false
            var isClusterIdle = true
            var numWorkersVisited = 0
            while (numWorkersVisited < numWorkersAlive && !launched) {
              val worker = shuffledAliveWorkers(curPos)
              isClusterIdle = worker.drivers.isEmpty && worker.executors.isEmpty
              numWorkersVisited += 1
              if (canLaunchDriver(worker, driver.desc)) {/*worker的资源是否满足driver启动条件*/
                val allocated = worker.acquireResources(driver.desc.resourceReqs)
                driver.withResources(allocated)
                launchDriver(worker, driver)/*启动driver程序  提交任务过多可能需要排队*/
                waitingDrivers -= driver
                launched = true
              }
              curPos = (curPos + 1) % numWorkersAlive
            }
            if (!launched && isClusterIdle) {
              logWarning(s"Driver ${driver.id} requires more resource than any of Workers could have.")
            }
        }
        startExecutorsOnWorkers()/*启动executor程序*/
    }

1.3.1.1.1 launchDriver(worker, driver) 详解

    private def launchDriver(worker: WorkerInfo, driver: DriverInfo): Unit = {
        logInfo("Launching driver " + driver.id + " on worker " + worker.id)
        worker.addDriver(driver)
        driver.worker = Some(worker)
        worker.endpoint.send(LaunchDriver(driver.id, driver.desc, driver.resources))
        driver.state = DriverState.RUNNING
    }//可以看到其实没有很多代码，主要是一个worker.send(LaunchDriver())这个方法等worker类的时候详解

1.3.1.1.2 startExecutorsOnWorkers() 详解

    private def startExecutorsOnWorkers(): Unit = {
        for (app <- waitingApps) {
            val coresPerExecutor = app.desc.coresPerExecutor.getOrElse(1)//默认是一个cpu
            if (app.coresLeft >= coresPerExecutor) {
                val usableWorkers = workers.toArray.filter(_.state == WorkerState.ALIVE)
                    .filter(canLaunchExecutor(_, app.desc))
                    .sortBy(_.coresFree).reverse  //找最空闲的节点  
                val appMayHang = waitingApps.length == 1 &&
                    waitingApps.head.executors.isEmpty && usableWorkers.isEmpty//这一块代码有点迷   最后一个app才判断嘛？不应该是全部都判断嘛
                if (appMayHang) {
                    logWarning(s"App ${app.id} requires more resource than any of Workers could have.")
                }
                val assignedCores = scheduleExecutorsOnWorkers(app, usableWorkers, spreadOutApps)//将可以执行的worker的进程数返回回来
                for (pos <- 0 until usableWorkers.length if assignedCores(pos) > 0) {/*分配CPU资源和启动Executor*/
                    allocateWorkerResourceToExecutors(
                        app, assignedCores(pos), app.desc.coresPerExecutor, usableWorkers(pos))
                }
            }
        }
    }

1.3.1.1.2.1 allocateWorkerResourceToExecutors()详解

    private def allocateWorkerResourceToExecutors(app: ApplicationInfo,assignedCores: Int,
          coresPerExecutor: Option[Int],worker: WorkerInfo): Unit = {
        val numExecutors = coresPerExecutor.map { assignedCores / _ }.getOrElse(1)
        val coresToAssign = coresPerExecutor.getOrElse(assignedCores)
        for (i <- 1 to numExecutors) {
          val allocated = worker.acquireResources(app.desc.resourceReqsPerExecutor)
          val exec = app.addExecutor(worker, coresToAssign, allocated)
          launchExecutor(worker, exec)/*启动Executor*/
          app.state = ApplicationState.RUNNING
        }
    }

1.3.1.1.2.1.1 launchExecutor 详解

    private def launchExecutor(worker: WorkerInfo, exec: ExecutorDesc): Unit = {
        worker.addExecutor(exec)
        worker.endpoint.send(LaunchExecutor(masterUrl, exec.application.id, exec.id,
          exec.application.desc, exec.cores, exec.memory, exec.resources))/*给worker发送启动Executor的程序*/
        exec.application.driver.send(
          ExecutorAdded(exec.id, worker.id, worker.hostPort, exec.cores, exec.memory))/*driver发送启动Executor的程序*/
    }
    其实最后就是两个消息：这一块其实是全部申请新资源，没有杀掉旧资源
    worker.send(LaunchExecutor)
    driver.send(ExecutorAdded)

二.CompleteRecovery 详解

    //上一步开始主备切换，但是没有杀掉旧的任务的情况其实在这里面
    private def completeRecovery(): Unit = {//这个方法其实就是主备切换完成的方法
        if (state != RecoveryState.RECOVERING) { return }
        state = RecoveryState.COMPLETING_RECOVERY
        workers.filter(_.state == WorkerState.UNKNOWN).foreach(
          removeWorker(_, "Not responding for recovery"))//worker去掉所有状态为UNKNOWN的
        apps.filter(_.state == ApplicationState.UNKNOWN).foreach(finishApplication)//app去掉所有状态为UNKNOWN的

        apps.filter(_.state == ApplicationState.WAITING).foreach(_.state = ApplicationState.RUNNING)//将所有app状态改为RUNNING

        drivers.filter(_.worker.isEmpty).foreach { d =>
          logWarning(s"Driver ${d.id} was not found after master recovery")
          if (d.desc.supervise) {
            logWarning(s"Re-launching ${d.id}")
            relaunchDriver(d)
          } else {
            removeDriver(d.id, DriverState.ERROR, None)
            logWarning(s"Did not re-launch ${d.id} because it was not supervised")
          }
        }

        state = RecoveryState.ALIVE
        schedule()
        logInfo("Recovery complete - resuming operations!")
    }

2.1 removeWorker 详解

    private def removeWorker(worker: WorkerInfo, msg: String): Unit = {
        logInfo("Removing worker " + worker.id + " on " + worker.host + ":" + worker.port)
        worker.setState(WorkerState.DEAD)
        idToWorker -= worker.id
        addressToWorker -= worker.endpoint.address//去除掉所有的旧worker 

        for (exec <- worker.executors.values) {
            logInfo("Telling app of lost executor: " + exec.id)
            exec.application.driver.send(ExecutorUpdated(
              exec.id, ExecutorState.LOST, Some("worker lost"), None, Some(worker.host)))//给所有的老的driver发送 ExecutorUpdated
            exec.state = ExecutorState.LOST
            exec.application.removeExecutor(exec)//去掉所有的老的任务的Executor 回收资源
        }
        for (driver <- worker.drivers.values) {
            if (driver.desc.supervise) {//两者的差别的是有没有新建driver
              logInfo(s"Re-launching ${driver.id}")
              relaunchDriver(driver)
            } else {
              logInfo(s"Not re-launching ${driver.id} because it was not supervised")
              removeDriver(driver.id, DriverState.ERROR, None)
            }
        }
        logInfo(s"Telling app of lost worker: " + worker.id)
        apps.filterNot(completedApps.contains(_)).foreach { app =>
            app.driver.send(WorkerRemoved(worker.id, worker.host, msg))//给所有driver发送WorkerRemoved 消息
        }
        persistenceEngine.removeWorker(worker)
        schedule()
    }

2.1.1 relaunchDriver 详解

    private def relaunchDriver(driver: DriverInfo): Unit = {
        removeDriver(driver.id, DriverState.RELAUNCHING, None)//移除driver 回收资源
        val newDriver = createDriver(driver.desc)//创建新的Driver
        persistenceEngine.addDriver(newDriver)
        drivers.add(newDriver)
        waitingDrivers += newDriver

        schedule()
    }

2.1.1.1 removeDriver 详解

    private def removeDriver(driverId: String,finalState: DriverState,exception: Option[Exception]): Unit = {
        drivers.find(d => d.id == driverId) match {
          case Some(driver) =>
            logInfo(s"Removing driver: $driverId")
            drivers -= driver
            if (completedDrivers.size >= retainedDrivers) {
              val toRemove = math.max(retainedDrivers / 10, 1)
              completedDrivers.trimStart(toRemove)
            }
            completedDrivers += driver
            persistenceEngine.removeDriver(driver)
            driver.state = finalState
            driver.exception = exception
            driver.worker.foreach(w => w.removeDriver(driver))//移除所有driver  回收driver资源
            schedule()
          case None =>
            logWarning(s"Asked to remove unknown driver: $driverId")
        }
    }