小记--------spark的Master的Application注册机制源码分析及Master的注册机制原理分析

原理图解：

Master类位置所在：spark-core_2.11-2.1.0.jar的org.apache.spark.deploy.master下的Master类

 

//截取了部分代码
//处理Application注册的请求
case RegisterApplication(description, driver) =>
  //如果master的状态是standby，也就是当前这个master，是standby master，不是active master
  //那么Application来请求注册，什么都不会干
  // TODO Prevent repeated registrations from some driver
  if (state == RecoveryState.STANDBY) {
    // ignore, don't send response
  } else {
    logInfo("Registering app " + description.name)
    //用ApplicationDescription信息，创建ApplicationInfo
    val app = createApplication(description, driver)
    //注册Application
    //将ApplicationInfo加入缓存，将Application加入等待调度的队列--waitingApps
    registerApplication(app)//详细代码见：代码1
    logInfo("Registered app " + description.name + " with ID " + app.id)
    //使用持久化引擎，将ApplicationInfo进行持久化
    persistenceEngine.addApplication(app)
        //反向，向SparkDeploySchedulerBackend的APPClient的ClientActor，发送消息，也就是RegisteredApplication
    driver.send(RegisteredApplication(app.id, self))
    schedule()//schedule 重新调度，--至此Application注册完成
  }
代码1
private def registerApplication(app: ApplicationInfo): Unit = {
  val appAddress = app.driver.address
  if (addressToApp.contains(appAddress)) {
    logInfo("Attempted to re-register application at same address: " + appAddress)
    return
  }
 
  applicationMetricsSystem.registerSource(app.appSource)
 
//这里其实就是将APP的信息加入内存缓存中
  apps += app
  idToApp(app.id) = app
  endpointToApp(app.driver) = app
  addressToApp(appAddress) = app
 
//将APP加入等待调度的队列中 waitingApps就是一个ArrayBuffer
  waitingApps += app
  if (reverseProxy) {
    webUi.addProxyTargets(app.id, app.desc.appUiUrl)
  }
}