【原创】大叔经验分享（19）spark on yarn提交任务之后执行进度总是10%

spark 2.1.1

系统中希望监控spark on yarn任务的执行进度，但是监控过程发现提交任务之后执行进度总是10%，直到执行成功或者失败，进度会突然变为100%，很神奇，

下面看spark on yarn任务提交过程：

spark on yarn提交任务时会把mainClass修改为Client

childMainClass = "org.apache.spark.deploy.yarn.Client"

spark-submit过程详见：https://www.cnblogs.com/barneywill/p/9820684.html

下面看Client执行过程：

org.apache.spark.deploy.yarn.Client

  def main(argStrings: Array[String]) {
...
    val sparkConf = new SparkConf
    // SparkSubmit would use yarn cache to distribute files & jars in yarn mode,
    // so remove them from sparkConf here for yarn mode.
    sparkConf.remove("spark.jars")
    sparkConf.remove("spark.files")
    val args = new ClientArguments(argStrings)
    new Client(args, sparkConf).run()
...

  def run(): Unit = {
    this.appId = submitApplication()
...

  def submitApplication(): ApplicationId = {
...
      val containerContext = createContainerLaunchContext(newAppResponse)
...

  private def createContainerLaunchContext(newAppResponse: GetNewApplicationResponse)
    : ContainerLaunchContext = {
...
    val amClass =
      if (isClusterMode) {
        Utils.classForName("org.apache.spark.deploy.yarn.ApplicationMaster").getName
      } else {
        Utils.classForName("org.apache.spark.deploy.yarn.ExecutorLauncher").getName
      }

这里调用过程为Client.main->run->submitApplication->createContainerLaunchContext，然后会设置amClass，最终都会调用到ApplicationMaster，因为ExecutorLauncher内部也是调用ApplicationMaster，如下：

org.apache.spark.deploy.yarn.ExecutorLauncher

object ExecutorLauncher {

  def main(args: Array[String]): Unit = {
    ApplicationMaster.main(args)
  }

}

下面看ApplicationMaster：

org.apache.spark.deploy.yarn.ApplicationMaster

  def main(args: Array[String]): Unit = {
...
    SparkHadoopUtil.get.runAsSparkUser { () =>
      master = new ApplicationMaster(amArgs, new YarnRMClient)
      System.exit(master.run())
    }
...

  final def run(): Int = {
...
      if (isClusterMode) {
        runDriver(securityMgr)
      } else {
        runExecutorLauncher(securityMgr)
      }
...

  private def registerAM(
      _sparkConf: SparkConf,
      _rpcEnv: RpcEnv,
      driverRef: RpcEndpointRef,
      uiAddress: String,
      securityMgr: SecurityManager) = {
...
    allocator = client.register(driverUrl,
      driverRef,
      yarnConf,
      _sparkConf,
      uiAddress,
      historyAddress,
      securityMgr,
      localResources)

    allocator.allocateResources()
    reporterThread = launchReporterThread()
...
  private def launchReporterThread(): Thread = {
    // The number of failures in a row until Reporter thread give up
    val reporterMaxFailures = sparkConf.get(MAX_REPORTER_THREAD_FAILURES)

    val t = new Thread {
      override def run() {
        var failureCount = 0
        while (!finished) {
          try {
            if (allocator.getNumExecutorsFailed >= maxNumExecutorFailures) {
              finish(FinalApplicationStatus.FAILED,
                ApplicationMaster.EXIT_MAX_EXECUTOR_FAILURES,
                s"Max number of executor failures ($maxNumExecutorFailures) reached")
            } else {
              logDebug("Sending progress")
              allocator.allocateResources()
            }
...

这里调用过程为ApplicationMaster.main->run，run中会调用runDriver或者runExecutorLauncher，最终都会调用到registerAM，其中会调用YarnAllocator.allocateResources，然后在launchReporterThread中会启动一个thread，其中也会不断调用YarnAllocator.allocateResources，下面看YarnAllocator：

org.apache.spark.deploy.yarn.YarnAllocator

  def allocateResources(): Unit = synchronized {
    updateResourceRequests()

    val progressIndicator = 0.1f
    // Poll the ResourceManager. This doubles as a heartbeat if there are no pending container
    // requests.
    val allocateResponse = amClient.allocate(progressIndicator)

可见这里会设置进度为0.1，即10%，而且是硬编码，所以spark on yarn的执行进度一直为10%，所以想监控spark on yarn的任务进度看来是徒劳的；