解析spark源码yarn-cluster模式任务提交
目录
一，运行命令
二，任务提交流程图
三，启动脚本
四，程序入口类org.apache.spark.deploy.SparkSubmit
五，org.apache.spark.deploy.yarn.YarnClusterApplication类
六， org.apache.spark.deploy.yarn.ApplicationMaster 类。
一，运行命令
bin/spark-submit \
--master yarn \
--deploy-mode cluster \
--class org.apache.spark.examples.SparkPi \
examples/jars/spark-examples_2.11-2.3.1.3.0.1.0-187.jar
二，任务提交流程图
查看spark-submit 脚本文件，程序入口为
exec "${SPARK_HOME}"/bin/spark-class org.apache.spark.deploy.SparkSubmit "$@“
查看${SPARK_HOME}"/bin/spark-class可知该脚本执行了java -cp main-class 命令启动了一个java进程,进程名为SparkSubmit，main函数在主类org.apache.spark.deploy.SparkSubmit中。
实际执行的具体命令为：
/etc/alternatives/jre/bin/java -Dhdp.version=3.0.1.0-187 -cp /usr/hdp/3.0.1.0-187/spark2/conf/:/usr/hdp/3.0.1.0-187/spark2/jars/*:/usr/hdp/3.0.1.0-187/hadoop/conf/ -Xmx1g org.apache.spark.deploy.SparkSubmit --master yarn --class org.apache.spark.examples.SparkPi examples/jars/spark-examples_2.11-2.3.1.3.0.1.0-187.jar
四，程序入口类org.apache.spark.deploy.SparkSubmit
该类有个伴生对象，其中有main函数,创建了SparkSubmit对象并执行doSubmit()；
override def main(args: Array[String]): Unit = {
val submit = new SparkSubmit() {...}
submit.doSubmit(args)
}
doSubmit 解析args参数，封装到appArgs:SparkSubmitArguments对象中，然后执行submit(appArgs, uninitLog)。
def doSubmit(args: Array[String]): Unit = {
// Initialize logging if it hasn't been done yet. Keep track of whether logging needs to
// be reset before the application starts.
val uninitLog = initializeLogIfNecessary(true, silent = true)
val appArgs = parseArguments(args)
if (appArgs.verbose) {
logInfo(appArgs.toString)
}
appArgs.action match {
case SparkSubmitAction.SUBMIT => submit(appArgs, uninitLog)
case SparkSubmitAction.KILL => kill(appArgs)
case SparkSubmitAction.REQUEST_STATUS => requestStatus(appArgs)
case SparkSubmitAction.PRINT_VERSION => printVersion()
}
}
submit(appArgs, uninitLog) 调用 runMain(args: SparkSubmitArguments, uninitLog: Boolean)
private def runMain(args: SparkSubmitArguments, uninitLog: Boolean): Unit = {
val (childArgs, childClasspath, sparkConf, childMainClass) = prepareSubmitEnvironment(args)
.
.
.
try {
mainClass = Utils.classForName(childMainClass)
} catch {...}
val app: SparkApplication = if (classOf[SparkApplication].isAssignableFrom(mainClass)) {
mainClass.getConstructor().newInstance().asInstanceOf[SparkApplication]
} else {
new JavaMainApplication(mainClass)
}
.
.
.
try {
app.start(childArgs.toArray, sparkConf)
} catch {
case t: Throwable =>
throw findCause(t)
}
}
这里mainClass十分重要，先判读mainClass是否是SparkApplication的子类，如果是则通过反射调用其构造器创建对象；
如果不是则创建一个JavaMainApplication（是SparkApplication的子类）对象并在其override def start(args: Array[String], conf: SparkConf)函数中利用反射执行mainClass中main函数。
SparkApplication创建完毕后执行其start(childArgs.toArray, sparkConf) 方法。
/**
* Entry point for a Spark application. Implementations must provide a no-argument constructor.
*/
private[spark] trait SparkApplication {
def start(args: Array[String], conf: SparkConf): Unit
}
/**
* Implementation of SparkApplication that wraps a standard Java class with a "main" method.
*
* Configuration is propagated to the application via system properties, so running multiple
* of these in the same JVM may lead to undefined behavior due to configuration leaks.
*/
private[deploy] class JavaMainApplication(klass: Class[_]) extends SparkApplication {
override def start(args: Array[String], conf: SparkConf): Unit = {
val mainMethod = klass.getMethod("main", new Array[String](0).getClass)
if (!Modifier.isStatic(mainMethod.getModifiers)) {
throw new IllegalStateException("The main method in the given main class must be static")
}
val sysProps = conf.getAll.toMap
sysProps.foreach { case (k, v) =>
sys.props(k) = v
}
mainMethod.invoke(null, args)
}
}
如果**–deploy-mode** 是client mainClass的值由命令行参数 –class 决定，也就是org.apache.spark.examples.SparkPi。
这种情况下会在当前虚拟机中执行客户端代码，如果是其它条件情况会比较复杂。
以上文指定的运行命令为例，这里mainClass是org.apache.spark.deploy.yarn.YarnClusterApplication类class对象。
private[deploy] val YARN_CLUSTER_SUBMIT_CLASS =
"org.apache.spark.deploy.yarn.YarnClusterApplication"
...
if (isYarnCluster) {
childMainClass = YARN_CLUSTER_SUBMIT_CLASS
if (args.isPython) {
childArgs += ("--primary-py-file", args.primaryResource)
childArgs += ("--class", "org.apache.spark.deploy.PythonRunner")
} else if (args.isR) {
val mainFile = new Path(args.primaryResource).getName
childArgs += ("--primary-r-file", mainFile)
childArgs += ("--class", "org.apache.spark.deploy.RRunner")
} else {
if (args.primaryResource != SparkLauncher.NO_RESOURCE) {
childArgs += ("--jar", args.primaryResource)
}
childArgs += ("--class", args.mainClass)
}
if (args.childArgs != null) {
args.childArgs.foreach { arg => childArgs += ("--arg", arg) }
}
}
五，org.apache.spark.deploy.yarn.YarnClusterApplication类
该类在spark-yarn包中。
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-yarn_${scala.version}</artifactId>
<version>${spark.version}</version>
</dependency>
开始执行其override def start(args: Array[String], conf: SparkConf) 方法。
private[spark] class YarnClusterApplication extends SparkApplication {
override def start(args: Array[String], conf: SparkConf): Unit = {
// SparkSubmit would use yarn cache to distribute files & jars in yarn mode,
// so remove them from sparkConf here for yarn mode.
conf.remove(JARS)
conf.remove(FILES)
new Client(new ClientArguments(args), conf, null).run()
}
}
SparkSubmi进程中创建一个客户端Client，该类是一个代理类其中包括YarnClient，执行run() 方法。
提交Application给yarn集群ResourceManager，提交成功后返回appid，
如果spark.submit.deployMode=cluster&&spark.yarn.submit.waitAppCompletion=true，
SparkSubmit进程会定期输出appId日志直到任务结束(monitorApplication(appId))，否则会输出一次日志然后退出。
def run(): Unit = {
this.appId = submitApplication()
if (!launcherBackend.isConnected() && fireAndForget) {
val report = getApplicationReport(appId)
val state = report.getYarnApplicationState
logInfo(s"Application report for $appId (state: $state)")
logInfo(formatReportDetails(report))
if (state == YarnApplicationState.FAILED || state == YarnApplicationState.KILLED) {
throw new SparkException(s"Application $appId finished with status: $state")
}
} else {
val YarnAppReport(appState, finalState, diags) = monitorApplication(appId)
if (appState == YarnApplicationState.FAILED || finalState == FinalApplicationStatus.FAILED) {
diags.foreach { err =>
logError(s"Application diagnostics message: $err")
}
throw new SparkException(s"Application $appId finished with failed status")
}
if (appState == YarnApplicationState.KILLED || finalState == FinalApplicationStatus.KILLED) {
throw new SparkException(s"Application $appId is killed")
}
if (finalState == FinalApplicationStatus.UNDEFINED) {
throw new SparkException(s"The final status of application $appId is undefined")
}
}
}
继续跟踪submitApplication()
def submitApplication(): ApplicationId = {
ResourceRequestHelper.validateResources(sparkConf)
var appId: ApplicationId = null
try {
launcherBackend.connect()
yarnClient.init(hadoopConf)
yarnClient.start()
logInfo("Requesting a new application from cluster with %d NodeManagers"
.format(yarnClient.getYarnClusterMetrics.getNumNodeManagers))
// Get a new application from our RM
val newApp = yarnClient.createApplication()
val newAppResponse = newApp.getNewApplicationResponse()
appId = newAppResponse.getApplicationId()
// The app staging dir based on the STAGING_DIR configuration if configured
// otherwise based on the users home directory.
val appStagingBaseDir = sparkConf.get(STAGING_DIR)
.map { new Path(_, UserGroupInformation.getCurrentUser.getShortUserName) }
.getOrElse(FileSystem.get(hadoopConf).getHomeDirectory())
stagingDirPath = new Path(appStagingBaseDir, getAppStagingDir(appId))
new CallerContext("CLIENT", sparkConf.get(APP_CALLER_CONTEXT),
Option(appId.toString)).setCurrentContext()
// Verify whether the cluster has enough resources for our AM
verifyClusterResources(newAppResponse)
// Set up the appropriate contexts to launch our AM
val containerContext = createContainerLaunchContext(newAppResponse)
val appContext = createApplicationSubmissionContext(newApp, containerContext)
// Finally, submit and monitor the application
logInfo(s"Submitting application $appId to ResourceManager")
yarnClient.submitApplication(appContext)
launcherBackend.setAppId(appId.toString)
reportLauncherState(SparkAppHandle.State.SUBMITTED)
appId
} catch {
case e: Throwable =>
if (stagingDirPath != null) {
cleanupStagingDir()
}
throw e
}
该方法做了如下工作（对应于任务提交流程图中的1，2，3）：
1，向ResourceManager发送请求创建Application，获取全局唯一的
appId。
2，根据配置的缓存目录信息+appId信息，创建运行Application运行的缓存目录stagingDirPath。
3，verifyClusterResources 验证集群中是否有足够资源可用，没有的话抛出异常。
4，createContainerLaunchContext 创建Container，其中封装了Container进程的启动命令。
5，提交appContext。
查看createContainerLaunchContext(newAppResponse) 代码。
val amClass =
if (isClusterMode) {
Utils.classForName("org.apache.spark.deploy.yarn.ApplicationMaster").getName
} else {
Utils.classForName("org.apache.spark.deploy.yarn.ExecutorLauncher").getName
}
...
// Command for the ApplicationMaster
val commands = prefixEnv ++
Seq(Environment.JAVA_HOME.$$() + "/bin/java", "-server") ++
javaOpts ++ amArgs ++
Seq(
"1>", ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stdout",
"2>", ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stderr")
// TODO: it would be nicer to just make sure there are no null commands here
val printableCommands = commands.map(s => if (s == null) "null" else s).toList
amContainer.setCommands(printableCommands.asJava)
六， org.apache.spark.deploy.yarn.ApplicationMaster 类。Container的启动代码大概为
bin/java -server org.apache.spark.deploy.yarn.ApplicationMaster --class …
yarn集群某一个NodeManager收到ResourceManager的命令，启动ApplicationMaster进程，对应任务提交流程图中的步骤4.
查看ApplicationMaster 伴生对象中的main方法。
def main(args: Array[String]): Unit = {
SignalUtils.registerLogger(log)
val amArgs = new ApplicationMasterArguments(args)
val sparkConf = new SparkConf()
if (amArgs.propertiesFile != null) {
Utils.getPropertiesFromFile(amArgs.propertiesFile).foreach { case (k, v) =>
sparkConf.set(k, v)
}
}
// Set system properties for each config entry. This covers two use cases:
// - The default configuration stored by the SparkHadoopUtil class
// - The user application creating a new SparkConf in cluster mode
//
// Both cases create a new SparkConf object which reads these configs from system properties.
sparkConf.getAll.foreach { case (k, v) =>
sys.props(k) = v
}
val yarnConf = new YarnConfiguration(SparkHadoopUtil.newConfiguration(sparkConf))
master = new ApplicationMaster(amArgs, sparkConf, yarnConf)
val ugi = sparkConf.get(PRINCIPAL) match {
// We only need to log in with the keytab in cluster mode. In client mode, the driver
// handles the user keytab.
case Some(principal) if master.isClusterMode =>
val originalCreds = UserGroupInformation.getCurrentUser().getCredentials()
SparkHadoopUtil.get.loginUserFromKeytab(principal, sparkConf.get(KEYTAB).orNull)
val newUGI = UserGroupInformation.getCurrentUser()
if (master.appAttemptId == null || master.appAttemptId.getAttemptId > 1) {
// Re-obtain delegation tokens if this is not a first attempt, as they might be outdated
// as of now. Add the fresh tokens on top of the original user's credentials (overwrite).
// Set the context class loader so that the token manager has access to jars
// distributed by the user.
Utils.withContextClassLoader(master.userClassLoader) {
val credentialManager = new HadoopDelegationTokenManager(sparkConf, yarnConf, null)
credentialManager.obtainDelegationTokens(originalCreds)
}
}
// Transfer the original user's tokens to the new user, since it may contain needed tokens
// (such as those user to connect to YARN).
newUGI.addCredentials(originalCreds)
newUGI
case _ =>
SparkHadoopUtil.get.createSparkUser()
}
ugi.doAs(new PrivilegedExceptionAction[Unit]() {
override def run(): Unit = System.exit(master.run())
})
}
创建了ApplicationMaster对象并执行其run() 方法。
final def run(): Int = {
try {
val attemptID = if (isClusterMode) {
// Set the web ui port to be ephemeral for yarn so we don't conflict with
// other spark processes running on the same box
System.setProperty(UI_PORT.key, "0")
// Set the master and deploy mode property to match the requested mode.
System.setProperty("spark.master", "yarn")
System.setProperty(SUBMIT_DEPLOY_MODE.key, "cluster")
// Set this internal configuration if it is running on cluster mode, this
// configuration will be checked in SparkContext to avoid misuse of yarn cluster mode.
System.setProperty("spark.yarn.app.id", appAttemptId.getApplicationId().toString())
Option(appAttemptId.getAttemptId.toString)
} else {
None
}
new CallerContext(
"APPMASTER", sparkConf.get(APP_CALLER_CONTEXT),
Option(appAttemptId.getApplicationId.toString), attemptID).setCurrentContext()
logInfo("ApplicationAttemptId: " + appAttemptId)
// This shutdown hook should run *after* the SparkContext is shut down.
val priority = ShutdownHookManager.SPARK_CONTEXT_SHUTDOWN_PRIORITY - 1
ShutdownHookManager.addShutdownHook(priority) { () =>
val maxAppAttempts = client.getMaxRegAttempts(sparkConf, yarnConf)
val isLastAttempt = appAttemptId.getAttemptId() >= maxAppAttempts
if (!finished) {
// The default state of ApplicationMaster is failed if it is invoked by shut down hook.
// This behavior is different compared to 1.x version.
// If user application is exited ahead of time by calling System.exit(N), here mark
// this application as failed with EXIT_EARLY. For a good shutdown, user shouldn't call
// System.exit(0) to terminate the application.
finish(finalStatus,
ApplicationMaster.EXIT_EARLY,
"Shutdown hook called before final status was reported.")
}
if (!unregistered) {
// we only want to unregister if we don't want the RM to retry
if (finalStatus == FinalApplicationStatus.SUCCEEDED || isLastAttempt) {
unregister(finalStatus, finalMsg)
cleanupStagingDir(new Path(System.getenv("SPARK_YARN_STAGING_DIR")))
}
}
}
if (isClusterMode) {
runDriver()
} else {
runExecutorLauncher()
}
} catch {
case e: Exception =>
// catch everything else if not specifically handled
logError("Uncaught exception: ", e)
finish(FinalApplicationStatus.FAILED,
ApplicationMaster.EXIT_UNCAUGHT_EXCEPTION,
"Uncaught exception: " + StringUtils.stringifyException(e))
} finally {
try {
metricsSystem.foreach { ms =>
ms.report()
ms.stop()
}
} catch {
case e: Exception =>
logWarning("Exception during stopping of the metric system: ", e)
}
}
exitCode
}
执行runDriver()方法。
userClassThread = startUserApplication() 启动了一个名为Driver的线程，该线程中通过反射执行命令行中**–class指定的类（org.apache.spark.examples.SparkPi）中的main**函数，初始化SparkContext。主线程唤醒后，向ResourceManager注册ApplicationMaster，步骤5；
private def runDriver(): Unit = {
addAmIpFilter(None, System.getenv(ApplicationConstants.APPLICATION_WEB_PROXY_BASE_ENV))
userClassThread = startUserApplication()
// This a bit hacky, but we need to wait until the spark.driver.port property has
// been set by the Thread executing the user class.
logInfo("Waiting for spark context initialization...")
val totalWaitTime = sparkConf.get(AM_MAX_WAIT_TIME)
try {
val sc = ThreadUtils.awaitResult(sparkContextPromise.future,
Duration(totalWaitTime, TimeUnit.MILLISECONDS))
if (sc != null) {
val rpcEnv = sc.env.rpcEnv
val userConf = sc.getConf
val host = userConf.get(DRIVER_HOST_ADDRESS)
val port = userConf.get(DRIVER_PORT)
registerAM(host, port, userConf, sc.ui.map(_.webUrl), appAttemptId)
val driverRef = rpcEnv.setupEndpointRef(
RpcAddress(host, port),
YarnSchedulerBackend.ENDPOINT_NAME)
createAllocator(driverRef, userConf, rpcEnv, appAttemptId, distCacheConf)
} else {
// Sanity check; should never happen in normal operation, since sc should only be null
// if the user app did not create a SparkContext.
throw new IllegalStateException("User did not initialize spark context!")
}
resumeDriver()
userClassThread.join()
} catch {
case e: SparkException if e.getCause().isInstanceOf[TimeoutException] =>
logError(
s"SparkContext did not initialize after waiting for $totalWaitTime ms. " +
"Please check earlier log output for errors. Failing the application.")
finish(FinalApplicationStatus.FAILED,
ApplicationMaster.EXIT_SC_NOT_INITED,
"Timed out waiting for SparkContext.")
} finally {
resumeDriver()
}
}
private def startUserApplication(): Thread = {
logInfo("Starting the user application in a separate Thread")
var userArgs = args.userArgs
if (args.primaryPyFile != null && args.primaryPyFile.endsWith(".py")) {
// When running pyspark, the app is run using PythonRunner. The second argument is the list
// of files to add to PYTHONPATH, which Client.scala already handles, so it's empty.
userArgs = Seq(args.primaryPyFile, "") ++ userArgs
}
if (args.primaryRFile != null &&
(args.primaryRFile.endsWith(".R") || args.primaryRFile.endsWith(".r"))) {
// TODO(davies): add R dependencies here
}
val mainMethod = userClassLoader.loadClass(args.userClass)
.getMethod("main", classOf[Array[String]])
val userThread = new Thread {
override def run(): Unit = {
try {
if (!Modifier.isStatic(mainMethod.getModifiers)) {
logError(s"Could not find static main method in object ${args.userClass}")
finish(FinalApplicationStatus.FAILED, ApplicationMaster.EXIT_EXCEPTION_USER_CLASS)
} else {
mainMethod.invoke(null, userArgs.toArray)
finish(FinalApplicationStatus.SUCCEEDED, ApplicationMaster.EXIT_SUCCESS)
logDebug("Done running user class")
}
} catch {
case e: InvocationTargetException =>
e.getCause match {
case _: InterruptedException =>
// Reporter thread can interrupt to stop user class
case SparkUserAppException(exitCode) =>
val msg = s"User application exited with status $exitCode"
logError(msg)
finish(FinalApplicationStatus.FAILED, exitCode, msg)
case cause: Throwable =>
logError("User class threw exception: " + cause, cause)
finish(FinalApplicationStatus.FAILED,
ApplicationMaster.EXIT_EXCEPTION_USER_CLASS,
"User class threw exception: " + StringUtils.stringifyException(cause))
}
sparkContextPromise.tryFailure(e.getCause())
} finally {
// Notify the thread waiting for the SparkContext, in case the application did not
// instantiate one. This will do nothing when the user code instantiates a SparkContext
// (with the correct master), or when the user code throws an exception (due to the
// tryFailure above).
sparkContextPromise.trySuccess(null)
}
}
}
userThread.setContextClassLoader(userClassLoader)
userThread.setName("Driver")
userThread.start()
userThread
}
注册完成后，主线程处理yarn返回的资源createAllocator(driverRef, userConf, rpcEnv, appAttemptId, distCacheConf)。
private def createAllocator(
driverRef: RpcEndpointRef,
_sparkConf: SparkConf,
rpcEnv: RpcEnv,
appAttemptId: ApplicationAttemptId,
distCacheConf: SparkConf): Unit = {
// In client mode, the AM may be restarting after delegation tokens have reached their TTL. So
// always contact the driver to get the current set of valid tokens, so that local resources can
// be initialized below.
if (!isClusterMode) {
val tokens = driverRef.askSync[Array[Byte]](RetrieveDelegationTokens)
if (tokens != null) {
SparkHadoopUtil.get.addDelegationTokens(tokens, _sparkConf)
}
}
val appId = appAttemptId.getApplicationId().toString()
val driverUrl = RpcEndpointAddress(driverRef.address.host, driverRef.address.port,
CoarseGrainedSchedulerBackend.ENDPOINT_NAME).toString
val localResources = prepareLocalResources(distCacheConf)
// Before we initialize the allocator, let's log the information about how executors will
// be run up front, to avoid printing this out for every single executor being launched.
// Use placeholders for information that changes such as executor IDs.
logInfo {
val executorMemory = _sparkConf.get(EXECUTOR_MEMORY).toInt
val executorCores = _sparkConf.get(EXECUTOR_CORES)
val dummyRunner = new ExecutorRunnable(None, yarnConf, _sparkConf, driverUrl, "<executorId>",
"<hostname>", executorMemory, executorCores, appId, securityMgr, localResources,
ResourceProfile.DEFAULT_RESOURCE_PROFILE_ID)
dummyRunner.launchContextDebugInfo()
}
allocator = client.createAllocator(
yarnConf,
_sparkConf,
appAttemptId,
driverUrl,
driverRef,
securityMgr,
localResources)
// Initialize the AM endpoint *after* the allocator has been initialized. This ensures
// that when the driver sends an initial executor request (e.g. after an AM restart),
// the allocator is ready to service requests.
rpcEnv.setupEndpoint("YarnAM", new AMEndpoint(rpcEnv, driverRef))
allocator.allocateResources()
val ms = MetricsSystem.createMetricsSystem(MetricsSystemInstances.APPLICATION_MASTER,
sparkConf, securityMgr)
val prefix = _sparkConf.get(YARN_METRICS_NAMESPACE).getOrElse(appId)
ms.registerSource(new ApplicationMasterSource(prefix, allocator))
// do not register static sources in this case as per SPARK-25277
ms.start(false)
metricsSystem = Some(ms)
reporterThread = launchReporterThread()
}
只看关键代码allocator.allocateResources()，处理分配的资源。
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)
val allocatedContainers = allocateResponse.getAllocatedContainers()
allocatorBlacklistTracker.setNumClusterNodes(allocateResponse.getNumClusterNodes)
if (allocatedContainers.size > 0) {
logDebug(("Allocated containers: %d. Current executor count: %d. " +
"Launching executor count: %d. Cluster resources: %s.")
.format(
allocatedContainers.size,
runningExecutors.size,
numExecutorsStarting.get,
allocateResponse.getAvailableResources))
handleAllocatedContainers(allocatedContainers.asScala)
}
val completedContainers = allocateResponse.getCompletedContainersStatuses()
if (completedContainers.size > 0) {
logDebug("Completed %d containers".format(completedContainers.size))
processCompletedContainers(completedContainers.asScala)
logDebug("Finished processing %d completed containers. Current running executor count: %d."
.format(completedContainers.size, runningExecutors.size))
}
}
如果分配的Container数量大于0，调用** handleAllocatedContainers(allocatedContainers.asScala)**
def handleAllocatedContainers(allocatedContainers: Seq[Container]): Unit = {
val containersToUse = new ArrayBuffer[Container](allocatedContainers.size)
// Match incoming requests by host
val remainingAfterHostMatches = new ArrayBuffer[Container]
for (allocatedContainer <- allocatedContainers) {
matchContainerToRequest(allocatedContainer, allocatedContainer.getNodeId.getHost,
containersToUse, remainingAfterHostMatches)
}
// Match remaining by rack. Because YARN's RackResolver swallows thread interrupts
// (see SPARK-27094), which can cause this code to miss interrupts from the AM, use
// a separate thread to perform the operation.
val remainingAfterRackMatches = new ArrayBuffer[Container]
if (remainingAfterHostMatches.nonEmpty) {
var exception: Option[Throwable] = None
val thread = new Thread("spark-rack-resolver") {
override def run(): Unit = {
try {
for (allocatedContainer <- remainingAfterHostMatches) {
val rack = resolver.resolve(allocatedContainer.getNodeId.getHost)
matchContainerToRequest(allocatedContainer, rack, containersToUse,
remainingAfterRackMatches)
}
} catch {
case e: Throwable =>
exception = Some(e)
}
}
}
thread.setDaemon(true)
thread.start()
try {
thread.join()
} catch {
case e: InterruptedException =>
thread.interrupt()
throw e
}
if (exception.isDefined) {
throw exception.get
}
}
// Assign remaining that are neither node-local nor rack-local
val remainingAfterOffRackMatches = new ArrayBuffer[Container]
for (allocatedContainer <- remainingAfterRackMatches) {
matchContainerToRequest(allocatedContainer, ANY_HOST, containersToUse,
remainingAfterOffRackMatches)
}
if (remainingAfterOffRackMatches.nonEmpty) {
logDebug(s"Releasing ${remainingAfterOffRackMatches.size} unneeded containers that were " +
s"allocated to us")
for (container <- remainingAfterOffRackMatches) {
internalReleaseContainer(container)
}
}
runAllocatedContainers(containersToUse)
logInfo("Received %d containers from YARN, launching executors on %d of them."
.format(allocatedContainers.size, containersToUse.size))
}
这里会根据主机host，机架rack等信息队container进行分配。完成后启动Container，runAllocatedContainers(containersToUse)。
private val launcherPool = ThreadUtils.newDaemonCachedThreadPool(
"ContainerLauncher", sparkConf.get(CONTAINER_LAUNCH_MAX_THREADS))
创建线程池launcherPool。
/**
* Launches executors in the allocated containers.
*/
private def runAllocatedContainers(containersToUse: ArrayBuffer[Container]): Unit = {
for (container <- containersToUse) {
executorIdCounter += 1
val executorHostname = container.getNodeId.getHost
val containerId = container.getId
val executorId = executorIdCounter.toString
assert(container.getResource.getMemory >= resource.getMemory)
logInfo(s"Launching container $containerId on host $executorHostname " +
s"for executor with ID $executorId")
def updateInternalState(): Unit = synchronized {
runningExecutors.add(executorId)
numExecutorsStarting.decrementAndGet()
executorIdToContainer(executorId) = container
containerIdToExecutorId(container.getId) = executorId
val containerSet = allocatedHostToContainersMap.getOrElseUpdate(executorHostname,
new HashSet[ContainerId])
containerSet += containerId
allocatedContainerToHostMap.put(containerId, executorHostname)
}
if (runningExecutors.size() < targetNumExecutors) {
numExecutorsStarting.incrementAndGet()
if (launchContainers) {
launcherPool.execute(() => {
try {
new ExecutorRunnable(
Some(container),
conf,
sparkConf,
driverUrl,
executorId,
executorHostname,
executorMemory,
executorCores,
appAttemptId.getApplicationId.toString,
securityMgr,
localResources,
ResourceProfile.DEFAULT_RESOURCE_PROFILE_ID // use until fully supported
).run()
updateInternalState()
} catch {
case e: Throwable =>
numExecutorsStarting.decrementAndGet()
if (NonFatal(e)) {
logError(s"Failed to launch executor $executorId on container $containerId", e)
// Assigned container should be released immediately
// to avoid unnecessary resource occupation.
amClient.releaseAssignedContainer(containerId)
} else {
throw e
}
}
})
} else {
// For test only
updateInternalState()
}
} else {
logInfo(("Skip launching executorRunnable as running executors count: %d " +
"reached target executors count: %d.").format(
runningExecutors.size, targetNumExecutors))
}
}
}
查看ExecutorRunnable 类，其中nmClient = NMClient.createNMClient()， NodeManager客户端，负责于NodeManager交互；其prepareCommand() 方法拼接了一个进程启动命令，大体格式为：
bin/java -server org.apache.spark.executor.YarnCoarseGrainedExecutorBackend ...
ApplicationMaster进程中的launcherPool线程池，会根据Container的个数挨个启动线程ExecutorRunnable，ExecutorRunnable中的NMClient会将拼接好的jvm启动命令发送给相关的NodeManager，启动Container进程，进程名为YarnCoarseGrainedExecutorBackend。
ExecutorRunnable完整代码：
private[yarn] class ExecutorRunnable(
container: Option[Container],
conf: YarnConfiguration,
sparkConf: SparkConf,
masterAddress: String,
executorId: String,
hostname: String,
executorMemory: Int,
executorCores: Int,
appId: String,
securityMgr: SecurityManager,
localResources: Map[String, LocalResource],
resourceProfileId: Int) extends Logging {
var rpc: YarnRPC = YarnRPC.create(conf)
var nmClient: NMClient = _
def run(): Unit = {
logDebug("Starting Executor Container")
nmClient = NMClient.createNMClient()
nmClient.init(conf)
nmClient.start()
startContainer()
}
def launchContextDebugInfo(): String = {
val commands = prepareCommand()
val env = prepareEnvironment()
s"""
|===============================================================================
|Default YARN executor launch context:
| env:
|${Utils.redact(sparkConf, env.toSeq).map { case (k, v) => s" $k -> $v\n" }.mkString}
| command:
| ${Utils.redactCommandLineArgs(sparkConf, commands).mkString(" \\ \n ")}
|
| resources:
|${localResources.map { case (k, v) => s" $k -> $v\n" }.mkString}
|===============================================================================""".stripMargin
}
def startContainer(): java.util.Map[String, ByteBuffer] = {
val ctx = Records.newRecord(classOf[ContainerLaunchContext])
.asInstanceOf[ContainerLaunchContext]
val env = prepareEnvironment().asJava
ctx.setLocalResources(localResources.asJava)
ctx.setEnvironment(env)
val credentials = UserGroupInformation.getCurrentUser().getCredentials()
val dob = new DataOutputBuffer()
credentials.writeTokenStorageToStream(dob)
ctx.setTokens(ByteBuffer.wrap(dob.getData()))
val commands = prepareCommand()
ctx.setCommands(commands.asJava)
ctx.setApplicationACLs(
YarnSparkHadoopUtil.getApplicationAclsForYarn(securityMgr).asJava)
// If external shuffle service is enabled, register with the Yarn shuffle service already
// started on the NodeManager and, if authentication is enabled, provide it with our secret
// key for fetching shuffle files later
if (sparkConf.get(SHUFFLE_SERVICE_ENABLED)) {
val secretString = securityMgr.getSecretKey()
val secretBytes =
if (secretString != null) {
// This conversion must match how the YarnShuffleService decodes our secret
JavaUtils.stringToBytes(secretString)
} else {
// Authentication is not enabled, so just provide dummy metadata
ByteBuffer.allocate(0)
}
ctx.setServiceData(Collections.singletonMap("spark_shuffle", secretBytes))
}
// Send the start request to the ContainerManager
try {
nmClient.startContainer(container.get, ctx)
} catch {
case ex: Exception =>
throw new SparkException(s"Exception while starting container ${container.get.getId}" +
s" on host $hostname", ex)
}
}
private def prepareCommand(): List[String] = {
// Extra options for the JVM
val javaOpts = ListBuffer[String]()
// Set the JVM memory
val executorMemoryString = executorMemory + "m"
javaOpts += "-Xmx" + executorMemoryString
// Set extra Java options for the executor, if defined
sparkConf.get(EXECUTOR_JAVA_OPTIONS).foreach { opts =>
val subsOpt = Utils.substituteAppNExecIds(opts, appId, executorId)
javaOpts ++= Utils.splitCommandString(subsOpt).map(YarnSparkHadoopUtil.escapeForShell)
}
// Set the library path through a command prefix to append to the existing value of the
// env variable.
val prefixEnv = sparkConf.get(EXECUTOR_LIBRARY_PATH).map { libPath =>
Client.createLibraryPathPrefix(libPath, sparkConf)
}
javaOpts += "-Djava.io.tmpdir=" +
new Path(Environment.PWD.$$(), YarnConfiguration.DEFAULT_CONTAINER_TEMP_DIR)
// Certain configs need to be passed here because they are needed before the Executor
// registers with the Scheduler and transfers the spark configs. Since the Executor backend
// uses RPC to connect to the scheduler, the RPC settings are needed as well as the
// authentication settings.
sparkConf.getAll
.filter { case (k, v) => SparkConf.isExecutorStartupConf(k) }
.foreach { case (k, v) => javaOpts += YarnSparkHadoopUtil.escapeForShell(s"-D$k=$v") }
// Commenting it out for now - so that people can refer to the properties if required. Remove
// it once cpuset version is pushed out.
// The context is, default gc for server class machines end up using all cores to do gc - hence
// if there are multiple containers in same node, spark gc effects all other containers
// performance (which can also be other spark containers)
// Instead of using this, rely on cpusets by YARN to enforce spark behaves 'properly' in
// multi-tenant environments. Not sure how default java gc behaves if it is limited to subset
// of cores on a node.
/*
else {
// If no java_opts specified, default to using -XX:+CMSIncrementalMode
// It might be possible that other modes/config is being done in
// spark.executor.extraJavaOptions, so we don't want to mess with it.
// In our expts, using (default) throughput collector has severe perf ramifications in
// multi-tenant machines
// The options are based on
// http://www.oracle.com/technetwork/java/gc-tuning-5-138395.html#0.0.0.%20When%20to%20Use
// %20the%20Concurrent%20Low%20Pause%20Collector|outline
javaOpts += "-XX:+UseConcMarkSweepGC"
javaOpts += "-XX:+CMSIncrementalMode"
javaOpts += "-XX:+CMSIncrementalPacing"
javaOpts += "-XX:CMSIncrementalDutyCycleMin=0"
javaOpts += "-XX:CMSIncrementalDutyCycle=10"
}
*/
// For log4j configuration to reference
javaOpts += ("-Dspark.yarn.app.container.log.dir=" + ApplicationConstants.LOG_DIR_EXPANSION_VAR)
val userClassPath = Client.getUserClasspath(sparkConf).flatMap { uri =>
val absPath =
if (new File(uri.getPath()).isAbsolute()) {
Client.getClusterPath(sparkConf, uri.getPath())
} else {
Client.buildPath(Environment.PWD.$(), uri.getPath())
}
Seq("--user-class-path", "file:" + absPath)
}.toSeq
YarnSparkHadoopUtil.addOutOfMemoryErrorArgument(javaOpts)
val commands = prefixEnv ++
Seq(Environment.JAVA_HOME.$$() + "/bin/java", "-server") ++
javaOpts ++
Seq("org.apache.spark.executor.YarnCoarseGrainedExecutorBackend",
"--driver-url", masterAddress,
"--executor-id", executorId,
"--hostname", hostname,
"--cores", executorCores.toString,
"--app-id", appId,
"--resourceProfileId", resourceProfileId.toString) ++
userClassPath ++
Seq(
s"1>${ApplicationConstants.LOG_DIR_EXPANSION_VAR}/stdout",
s"2>${ApplicationConstants.LOG_DIR_EXPANSION_VAR}/stderr")
// TODO: it would be nicer to just make sure there are no null commands here
commands.map(s => if (s == null) "null" else s).toList
}
private def prepareEnvironment(): HashMap[String, String] = {
val env = new HashMap[String, String]()
Client.populateClasspath(null, conf, sparkConf, env, sparkConf.get(EXECUTOR_CLASS_PATH))
System.getenv().asScala.filterKeys(_.startsWith("SPARK"))
.foreach { case (k, v) => env(k) = v }
sparkConf.getExecutorEnv.foreach { case (key, value) =>
if (key == Environment.CLASSPATH.name()) {
// If the key of env variable is CLASSPATH, we assume it is a path and append it.
// This is kept for backward compatibility and consistency with hadoop
YarnSparkHadoopUtil.addPathToEnvironment(env, key, value)
} else {
// For other env variables, simply overwrite the value.
env(key) = value
}
}
env
}
}
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