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本期內(nèi)容:
1、數(shù)據(jù)接收架構(gòu)設(shè)計(jì)模式
2、數(shù)據(jù)接收源碼徹底研究
1、Receiver接受數(shù)據(jù)的過(guò)程類似于MVC模式:
Receiver,ReceiverSupervisor和Driver的關(guān)系相當(dāng)于Model,Control,View,也就是MVC。
Model就是Receiver,存儲(chǔ)數(shù)據(jù)Control,就是ReceiverSupervisor,Driver是獲得元數(shù)據(jù),也就是View。
2、數(shù)據(jù)的位置信息會(huì)被封裝到RDD里面。
3、Receiver接受數(shù)據(jù),交給ReceiverSupervisor去存儲(chǔ)數(shù)據(jù)。
4、ReceiverTracker是通過(guò)發(fā)送一個(gè)又一個(gè)的Job,每個(gè)Job只有一個(gè)Task,每個(gè)Task里面就只有一個(gè)ReceiverSupervisor,用這個(gè)函數(shù)啟動(dòng)每一個(gè)Receiver。
下面我們簡(jiǎn)單的看下Receiver啟動(dòng)流程,應(yīng)用程序首先通過(guò)JobScheduler的start方法來(lái)啟動(dòng)receiverTracker的start方法:
def start(): Unit = synchronized { if (eventLoop != null) return // scheduler has already been started logDebug("Starting JobScheduler") eventLoop = new EventLoop[JobSchedulerEvent]("JobScheduler") { override protected def onReceive(event: JobSchedulerEvent): Unit = processEvent(event) override protected def onError(e: Throwable): Unit = reportError("Error in job scheduler", e) } eventLoop.start() // attach rate controllers of input streams to receive batch completion updates for { inputDStream <- ssc.graph.getInputStreams rateController <- inputDStream.rateController } ssc.addStreamingListener(rateController) listenerBus.start(ssc.sparkContext) receiverTracker = new ReceiverTracker(ssc) inputInfoTracker = new InputInfoTracker(ssc) receiverTracker.start() //receiver啟動(dòng) jobGenerator.start() logInfo("Started JobScheduler") }
通過(guò)調(diào)用receiverTracker.start()方法來(lái)進(jìn)行一系列的操作:
/** Start the endpoint and receiver execution thread. */ def start(): Unit = synchronized { if (isTrackerStarted) { throw new SparkException("ReceiverTracker already started") } if (!receiverInputStreams.isEmpty) { endpoint = ssc.env.rpcEnv.setupEndpoint( "ReceiverTracker", new ReceiverTrackerEndpoint(ssc.env.rpcEnv)) //Rpc消息通信,獲取receiver的狀態(tài) if (!skipReceiverLaunch) launchReceivers() //啟動(dòng)receiver logInfo("ReceiverTracker started") trackerState = Started } }
下面通過(guò)畫圖簡(jiǎn)單的描述下Receiver啟動(dòng)的內(nèi)部機(jī)制:
參考博客:http://blog.csdn.net/hanburgud/article/details/51471047
http://lqding.blog.51cto.com/9123978/1774426
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