Spark启动流程（Standalone）- master源码

Master源码

package org.apache.spark.deploy.master
//伴生类
private[deploy] class Master(
                                override val rpcEnv: RpcEnv,
                                address: RpcAddress,
                                webUiPort: Int,
                                val securityMgr: SecurityManager,
                                val conf: SparkConf)
    extends ThreadSafeRpcEndpoint with Logging with LeaderElectable
{
...
}
//伴生对象
private[deploy] object Master extends Logging{
    val SYSTEM_NAME = "sparkMaster"
    val ENDPOINT_NAME = "Master"
    
    // 启动 Master 的入口函数
    def main(argStrings: Array[String]) {
        Utils.initDaemon(log)
        val conf = new SparkConf
        // 构建用于参数解析的实例   
        //--host hadoop201 --port 7077 --webui-port 8080
        val args = new MasterArguments(argStrings, conf)
        // 启动 RPC 通信环境和 MasterEndPoint(通信终端)
       //<<1>>
        val (rpcEnv, _, _): (RpcEnv, Int, Option[Int]) = startRpcEnvAndEndpoint(args.host, args.port, args.webUiPort, conf)
        rpcEnv.awaitTermination()
    }
   ...
}

<< 1 >>、启动Mater返回一个三元组

    /**
      * Start the Master and return a three tuple of:
      * 启动 Master, 并返回一个三元组
      * (1) The Master RpcEnv
      * (2) The web UI bound port
      * (3) The REST server bound port, if any
      */
    def startRpcEnvAndEndpoint(
                                  host: String,
                                  port: Int,
                                  webUiPort: Int,
                                  conf: SparkConf): (RpcEnv, Int, Option[Int]) = {
        val securityMgr = new SecurityManager(conf)
        // 创建 Master 端的 RpcEnv 环境, 并启动 RpcEnv
        // 参数: sparkMaster hadoop201 7077 conf securityMgr
        // 返回值  的实际类型是: NettyRpcEnv
        //<< 1.1 >>
        val rpcEnv: RpcEnv = RpcEnv.create(SYSTEM_NAME, host, port, conf, securityMgr)
        // 创建 Master对象, 该对象就是一个 RpcEndpoint, 在 RpcEnv 中注册这个 RpcEndpoint
        // 返回该 RpcEndpoint 的引用, 使用该引用来接收信息和发送信息
        //<< 1.2 >>
        val masterEndpoint: RpcEndpointRef = rpcEnv.setupEndpoint(ENDPOINT_NAME,
            new Master(rpcEnv, rpcEnv.address, webUiPort, securityMgr, conf))
        // 向 Master 的通信终端发法请求，获取 BoundPortsResponse 对象
        // BoundPortsResponse 是一个样例类包含三个属性: rpcEndpointPort webUIPort restPort
        val portsResponse: BoundPortsResponse = masterEndpoint.askWithRetry[BoundPortsResponse](BoundPortsRequest)
        (rpcEnv, portsResponse.webUIPort, portsResponse.restPort)
    }

<< 1.1 >> RpcEnv的创建

def create(
              name: String,
              bindAddress: String,
              advertiseAddress: String,
              port: Int,
              conf: SparkConf,
              securityManager: SecurityManager,
              clientMode: Boolean): RpcEnv = {
    // 保存 RpcEnv 的配置信息
    val config = RpcEnvConfig(conf, name, bindAddress, advertiseAddress, port, securityManager,
        clientMode)
    // 创建 NettyRpcEvn
    //<< 1.1.1 >>
    new NettyRpcEnvFactory().create(config)
}

真正的创建是调用NettyRpcEnvFactory 的 create 方法创建

创建NettyRpcEnv的时候，会创建消息分发器，收件箱和存储远程地址与发件箱的Map

RpcEnv.scala

<< 1.1.1 >> NettyRpcEnvFactory （ NettyRpcEnv .scala）

private[rpc] class NettyRpcEnvFactory extends RpcEnvFactory with Logging {
    /*
    创建 NettyRpcEnv, 并且启动为后台程序
     */
    def create(config: RpcEnvConfig): RpcEnv = {
        val sparkConf: SparkConf = config.conf
        // Use JavaSerializerInstance in multiple threads is safe. However, if we plan to support
        // KryoSerializer in future, we have to use ThreadLocal to store SerializerInstance
        // 用于 Rpc传输对象时的序列化
        val javaSerializerInstance: JavaSerializerInstance = new JavaSerializer(sparkConf)
            .newInstance()
            .asInstanceOf[JavaSerializerInstance]
        // 实例化 NettyRpcEnv
        val nettyEnv = new NettyRpcEnv(
            sparkConf,
            javaSerializerInstance,
            config.advertiseAddress,
            config.securityManager)
        if (!config.clientMode) {
            // 定义 NettyRpcEnv 的启动函数
            val startNettyRpcEnv: Int => (NettyRpcEnv, Int) = { actualPort =>
                nettyEnv.startServer(config.bindAddress, actualPort)
                (nettyEnv, nettyEnv.address.port)
            }
            try {
                // 启动 NettyRpcEnv
                Utils.startServiceOnPort(config.port, startNettyRpcEnv, sparkConf, config.name)._1
            } catch {
                case NonFatal(e) =>
                    nettyEnv.shutdown()
                    throw e
            }
        }
        nettyEnv
    }
}

<< 1.2 >> Master伴生类(Master 端的 RpcEndpoint 启动)

Master是一个RpcEndpoint.

他的生命周期方法是: constructor -> onStart -> receive* -> onStop

onStart 主要代码片段

 // 创建 WebUI 服务器
 webUi = new MasterWebUI(this, webUiPort)


// 按照固定的频率去启动线程来检查 Worker 是否超时. 其实就是给自己发信息: CheckForWorkerTimeOut
// 默认是每分钟检查一次.
 checkForWorkerTimeOutTask = forwardMessageThread.scheduleAtFixedRate(new Runnable {
    override def run(): Unit = Utils.tryLogNonFatalError {
// 在 receive 方法中对 CheckForWorkerTimeOut 进行处理
       //<< 1.2.1 >>
        self.send(CheckForWorkerTimeOut)
    }
}, 0, WORKER_TIMEOUT_MS, TimeUnit.MILLISECONDS)


private val WORKER_TIMEOUT_MS = conf.getLong("spark.worker.timeout", 60) * 1000

<< 1.2.1 >> 检查并移除超时的worker

   /** Check for, and remove, any timed-out workers */
    private def timeOutDeadWorkers() {
        // Copy the workers into an array so we don't modify the hashset while iterating through it
        val currentTime = System.currentTimeMillis()
        //  把超时的 Worker 从 workers 中移除
//过滤出来要移除的worker：（上次心跳时间 小于 当前时间 减去 超时时间 ）即为超时
        val toRemove = workers.filter(_.lastHeartbeat < currentTime - WORKER_TIMEOUT_MS).toArray
        for (worker <- toRemove) {
            // 如果 worker 的状态不是 DEAD
            if (worker.state != WorkerState.DEAD) {
                logWarning("Removing %s because we got no heartbeat in %d seconds".format(
                    worker.id, WORKER_TIMEOUT_MS / 1000))
                removeWorker(worker) //
            } else {
                if (worker.lastHeartbeat < currentTime - ((REAPER_ITERATIONS + 1) * WORKER_TIMEOUT_MS)) {
                    workers -= worker // we've seen this DEAD worker in the UI, etc. for long enough; cull it
                }
            }
        }
    }