原文：http://hadoop.apache.org/common/docs/r0.23.0/hadoop-yarn/hadoop-yarn-site/WritingYarnApplications.html
目的
这个文档从比较高的层面上描述了如何编写一个YARN应用概念和流程
首先说的概念是“Application Submission Client”他负责将“Application”提交到YARN的Resource Manager.客户端通过ClientRMProtocol协议与ResourceManager联系，如果需要Client会通过ClientRPProtocol::getNewApplication来获取新的ApplicationId，然后通过ClientRMProtocol::submitApplication将应用提交运行。作为ClientRMProtocol::submitApplication调用的一部分，客户端需要足够的信息给ResourceManager来运行应用的第一个container也就是Applicationmaster.你需要提供如下一些信息：你的应用程序运行时所需要的local file/jars,执行时所运行的命令（包括必要的命令参数），Unix环境变量设置（可选的）等等。实际上你需要为ApplicationMaster提供Unix进程的描述信息。
YARN的ResourceManager会在一个获得的container上启动ApplicationMaster。ApplicationMaster然后通过AMRMProtocol协议与ResourceManager通讯，首先ApplicationMaster需要将自身注册到ResouceManager。ApplicationMaster为了完成交给他的任务，他会通过AMRMProtocol::allocate来申请containers。如果获得了container，ApplicationMaster会通过ContainerManager::startContainer和NodeManager联系，来为任务启动一个container。作为启动container的一部分，ApplicationMaster需要指定ContainerLaunchContext，ContainerLaunchContext和ApplicationSubmissionContext相似，包括了一些启动时需要的信息，诸如：命令行命令、环境变量等。一旦任务完成，ApplicationMaster会通过AMRMProtocol::finishApplicationMaster来通知ResourceManager任务完成。
与此同时，client可以通过查询ResourceManager来获取application的状态信息，或者如果ApplicationMaster支持也可以直接从ApplicationMaster查询信息。如果需要，client可以通过ClientRMProtocol::forceKillApplication来kill掉application。
接口
你可能关心的接口包括以下这些：
ClientRMProtocol -- Client <--> ResourceManager
这是client和ResourceManager通讯来启动一个新的application（这个application是ApplicationMaster等）的协议，可以通过这个协议查询或kill application。例如：a job-client将使用这个协议。
AMRMProtocol -- ApplicationMaster <-->ResourceManager
这个协议用于ApplicationManager向ResourceManager注册和注销自己，同时包括从Scheduler申请资源来完成任务。
ContainerManager - ApplicationMaster <-->NodeManager
这个协议用于ApplicationMaster和NodeManager来开始或停止一个container，或者获取container的状态更新信息。
写一个简单的Yarn应用
写一个简单的client
第一步是client连接到ResourceManager或者更具体一点说，连接到ResourceManager的ApplicationManager（AsM）接口
ClientRMProtocol applicationsManager;
YarnConfiguration yarnConf = new YarnConfiguration(conf);
InetSocketAddress rmAddress =
NetUtils.createSocketAddr(yarnConf.get(
YarnConfiguration.RM_ADDRESS,
YarnConfiguration.DEFAULT_RM_ADDRESS));
LOG.info("Connecting to ResourceManager at " + rmAddress);
configuration appsManagerServerConf = new Configuration(conf);
appsManagerServerConf.setClass(
YarnConfiguration.YARN_SECURITY_INFO,
ClientRMSecurityInfo.class, SecurityInfo.class);
applicationsManager = ((ClientRMProtocol) rpc.getProxy(
ClientRMProtocol.class, rmAddress, appsManagerServerConf)); 一旦ASM的handler获得后，client需要从ResourceManager获取一个ApplicationId
GetNewApplicationRequest request =
Records.newRecord(GetNewApplicationRequest.class);
GetNewApplicationResponse response =
applicationsManager.getNewApplication(request);
LOG.info("Got new ApplicationId=" + response.getApplicationId());从ASM返回的response也包含一些整个集群的信息，诸如minimum/maximum资源容量等。有了这些信息才能够适当的设置container的一些参数使得ApplicationMaster能够在这个container上运行。可以参考GetNewApplicationResponse获得更多细节信息。
client的一个关键工作就是设置ApplicationSubmissionContext，使得ResourceManager能够启动ApplicationMaster。client需要设置下面的一些context：
- Application Info：id和name
- 队列（Queue)，优先级信息（Priority info）：application将被提交到的队列，以及application被设定的优先级
- User：提交application的用户
- ContainerLaunchContext：ApplicationMaster被启动的container的一些信息。ContainerLaunchContext正如前面所描述的，定义了启动ApplicationMaster需要的信息包括local resource（binary,jars,files等等），security tokens，environment setting（CLASSPATH等）和被执行的command。
// Create a new ApplicationSubmissionContext
ApplicationSubmissionContext appContext =
Records.newRecord(ApplicationSubmissionContext.class);
// set the ApplicationId
appContext.setApplicationId(appId);
// set the application name
appContext.setApplicationName(appName);
// Create a new container launch context for the AM's container
ContainerLaunchContext amContainer =
Records.newRecord(ContainerLaunchContext.class);
// Define the local resources required
Map<String, LocalResource> localResources =
new HashMap<String, LocalResource>();
// Lets assume the jar we need for our ApplicationMaster is available in
// HDFS at a certain known path to us and we want to make it available to
// the ApplicationMaster in the launched container
Path jarPath; // <- known path to jar file
FileStatus jarStatus = fs.getFileStatus(jarPath);
LocalResource amJarRsrc = Records.newRecord(LocalResource.class);
// Set the type of resource - file or archive
// archives are untarred at the destination by the framework
amJarRsrc.setType(LocalResourceType.FILE);
// Set visibility of the resource
// Setting to most private option i.e. this file will only
// be visible to this instance of the running application
amJarRsrc.setVisibility(LocalResourceVisibility.APPLICATION);
// Set the location of resource to be copied over into the
// working directory
amJarRsrc.setResource(ConverterUtils.getYarnUrlFromPath(jarPath));
// Set timestamp and length of file so that the framework
// can do basic sanity checks for the local resource
// after it has been copied over to ensure it is the same
// resource the client intended to use with the application
amJarRsrc.setTimestamp(jarStatus.getModificationTime());
amJarRsrc.setSize(jarStatus.getLen());
// The framework will create a symlink called AppMaster.jar in the
// working directory that will be linked back to the actual file.
// The ApplicationMaster, if needs to reference the jar file, would
// need to use the symlink filename.
localResources.put("AppMaster.jar", amJarRsrc);
// Set the local resources into the launch context
amContainer.setLocalResources(localResources);
// Set up the environment needed for the launch context
Map<String, String> env = new HashMap<String, String>();
// For example, we could setup the classpath needed.
// Assuming our classes or jars are available as local resources in the
// working directory from which the command will be run, we need to append
// "." to the path.
// By default, all the hadoop specific classpaths will already be available
// in $CLASSPATH, so we should be careful not to overwrite it.
String classPathEnv = "$CLASSPATH:./*:";
env.put("CLASSPATH", classPathEnv);
amContainer.setEnvironment(env);
// Construct the command to be executed on the launched container
String command =
"${JAVA_HOME}" + /bin/java" +
" MyAppMaster" +
" arg1 arg2 arg3" +
" 1>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stdout" +
" 2>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stderr";
List<String> commands = new ArrayList<String>();
commands.add(command);
// add additional commands if needed
// Set the command array into the container spec
amContainer.setCommands(commands);
// Define the resource requirements for the container
// For now, YARN only supports memory so we set the memory
// requirements.
// If the process takes more than its allocated memory, it will
// be killed by the framework.
// Memory being requested for should be less than max capability
// of the cluster and all asks should be a multiple of the min capability.
Resource capability = Records.newRecord(Resource.class);
capability.setMemory(amMemory);
amContainer.setResource(capability);
// Set the container launch content into the ApplicationSubmissionContext
appContext.setAMContainerSpec(amContainer);进程信息设置完成后，client已经最终准备好提交任务到ASM
// Create the request to send to the ApplicationsManager
SubmitApplicationRequest appRequest =
Records.newRecord(SubmitApplicationRequest.class);
appRequest.setApplicationSubmissionContext(appContext);
// Submit the application to the ApplicationsManager
// Ignore the response as either a valid response object is returned on
// success or an exception thrown to denote the failure
applicationsManager.submitApplication(appRequest);这时，ResourceManager将接受这个application并且在后台根据设定的参数获取container并且在container上启动ApplicationManager
有多种办法client能够track progress的状态
client可以通过ClientRMProtocol::getApplicationReport和ResourceManager通讯来获取application的report
GetApplicationReportRequest reportRequest =
Records.newRecord(GetApplicationReportRequest.class);
reportRequest.setApplicationId(appId);
GetApplicationReportResponse reportResponse =
applicationsManager.getApplicationReport(reportRequest);
ApplicationReport report = reportResponse.getApplicationReport();从ResourceManager获取的ApplicationReport包含下面这些信息：
- 一般性application information：ApplicationId，application被提交到的queue，提交application的user，application开始的时间
- ApplicationMaster的详细信息：ApplicationMaster运行的主机，提供给client连接的rpc端口，以及client与ApplicationManager通讯需要的一个token
- Application tracking information：如果application支持某种类型的progress tracking，他可以设置监控的url，client可以通过ApplicationReport::getTrackingUrl来获取url并通过这个url来监控progress的状态
- ApplicationStatus：ResourceManager能够看到的一些application的状态，可以通过Application::getYarnApplicationState得到是否YarnApplicationState被设置为FINISHED，client可以通过ApplicationReport::getFinalApplicationStatus来check application的success/failure。在failures时，ApplicationReport::getDiagnostics可以提供一些关于failure的一些信息。
在特定条件下，如果应用花费了太长时间或者其他因素，client可能希望kill掉application。ClientRMProtocol支持forceKillApplication调用通过ResourceManager给Application发送一个kill消息。ApplicationMaster也可以通过设计为client提供abort调用，client通过rpc方式来调用。
KillApplicationRequest killRequest =
Records.newRecord(KillApplicationRequest.class);
killRequest.setApplicationId(appId);
applicationsManager.forceKillApplication(killRequest); 编写ApplicationMaster
ApplicationMaster是job的实际持有者，他由client通过ResouceManager启动，并被提供了job运行需要的必要的信息和资源，负责task的监督管理和相关工作的完成。
ApplicationMaster在多用户环境下可能与其他container运行在相同的物理主机上，因此假设他使用哪个预先配置的端口来监听都是不合理的。
当ApplicationMaster启动时，他可以通过环境变量来获得一些参数，诸如：ApplicationMaster所在container的ContainerId，application提交的时间，以及运行 ApplicationMaster的NodeManger host的细节信息，这些信息可以查阅ApplicationConstants来获得参数名称。
所有与ResouceManager的交互需要一个ApplicationAttemptId(如果任务失败可能会有多次尝试)，ApplicationAttemptId能够通过ApplicationMaster的containerId来获得，有相应的API可以完成从环境变量获得的字符串到对象的转换。
Map<String, String> envs = System.getenv();
String containerIdString =
envs.get(ApplicationConstants.AM_CONTAINER_ID_ENV);
if (containerIdString == null) {
// container id should always be set in the env by the framework
throw new IllegalArgumentException(
"ContainerId not set in the environment");
}
ContainerId containerId = ConverterUtils.toContainerId(containerIdString);
ApplicationAttemptId appAttemptID = containerId.getApplicationAttemptId();ApplicationMaster初始化完成后，可以通过ARMRMProtocol::registerApplicationMaster来向ResourceManager注册，ApplicationMaster通过ResouceManager的Scheduler接口来进行通讯。
// Connect to the Scheduler of the ResourceManager.
YarnConfiguration yarnConf = new YarnConfiguration(conf);
InetSocketAddress rmAddress =
NetUtils.createSocketAddr(yarnConf.get(
YarnConfiguration.RM_SCHEDULER_ADDRESS,
YarnConfiguration.DEFAULT_RM_SCHEDULER_ADDRESS));
LOG.info("Connecting to ResourceManager at " + rmAddress);
AMRMProtocol resourceManager =
(AMRMProtocol) rpc.getProxy(AMRMProtocol.class, rmAddress, conf);
// Register the AM with the RM
// Set the required info into the registration request:
// ApplicationAttemptId,
// host on which the app master is running
// rpc port on which the app master accepts requests from the client
// tracking url for the client to track app master progress
RegisterApplicationMasterRequest appMasterRequest =
Records.newRecord(RegisterApplicationMasterRequest.class);
appMasterRequest.setApplicationAttemptId(appAttemptID);
appMasterRequest.setHost(appMasterHostname);
appMasterRequest.setRpcPort(appMasterRpcPort);
appMasterRequest.setTrackingUrl(appMasterTrackingUrl);
// The registration response is useful as it provides information about the
// cluster.
// Similar to the GetNewApplicationResponse in the client, it provides
// information about the min/mx resource capabilities of the cluster that
// would be needed by the ApplicationMaster when requesting for containers.
RegisterApplicationMasterResponse response =
resourceManager.registerApplicationMaster(appMasterRequest);ApplicationMaster需要发出心跳通知ResouceManager，告知ApplicationMaster is alive and still running。在ResouceManager端设置的超时时间可以通过YarnConfiguration.RM_AM_EXPIRY_INTERVAL_MS来访问，缺省值定义下YarnConfiguration.DEFAULT_RM_AM_EXPIRY_INTERVAL_MS。对ResouceManager的AMRMProtocol::allocate调用可以算所是heatbeats，它还包含发送进程进展的相关信息。
依据任务的需求，ApplicationMaster可以申请一系列containers来运行任务。ApplicationMaster使用ResouceRequest类来指定container的specifications。具体包括：
- hostname：如果container需要host在特定的rack或主机上，需要设定这个参数，其中“*”代表container可以分配在任何主机上。
- Resouce capability：目前，YARN只支持Memeory base的资源需求分配，因此request只需要定义application需要多少memory。Memory的值以MB为单位，并且必须小于机群的max容量，并且是min容量的整数倍。内存是以物理内存使用来设定限制的。
- Priority：当申请到一些container时，ApplicationMaster可以给不同组的container设置不同的优先级，举例来说，对于Map-Reduce任务来说，ApplicationMaster可以给map container指定比较高的优先级，而给reduce container指定比较低的优先级。
// Resource Request
ResourceRequest rsrcRequest = Records.newRecord(ResourceRequest.class);
// setup requirements for hosts
// whether a particular rack/host is needed
// useful for applications that are sensitive
// to data locality
rsrcRequest.setHostName("*");
// set the priority for the request
Priority pri = Records.newRecord(Priority.class);
pri.setPriority(requestPriority);
rsrcRequest.setPriority(pri);
// Set up resource type requirements
// For now, only memory is supported so we set memory requirements
Resource capability = Records.newRecord(Resource.class);
capability.setMemory(containerMemory);
rsrcRequest.setCapability(capability);
// set no. of containers needed
// matching the specifications
rsrcRequest.setNumContainers(numContainers);定义了container requirement以后，ApplicationMaster需要构建AllocateRequest发送到ResourceManager。AllocateRequest包括：
- Requested containers：container specification和ApplicationMaster从ResourceManager处申请的container的数量
- Released containers：在有些情况下，ApplicationMaster可能申请了过多的container，它可以返还这些不用的container给ResourceManager，这些container可以分配给其他的应用使用。
- ResponseId：在allocate调用时保持在response当中的response id
- Progress update information：ApplicationMaster可以发送进程更新信息给ResourceManager，取值为0-1
List<ResourceRequest> requestedContainers;
List<ContainerId> releasedContainers
AllocateRequest req = Records.newRecord(AllocateRequest.class);
// The response id set in the request will be sent back in
// the response so that the ApplicationMaster can
// match it to its original ask and act appropriately.
req.setResponseId(rmRequestID);
// Set ApplicationAttemptId
req.setApplicationAttemptId(appAttemptID);
// Add the list of containers being asked for
req.addAllAsks(requestedContainers);
// If the ApplicationMaster has no need for certain
// containers due to over-allocation or for any other
// reason, it can release them back to the ResourceManager
req.addAllReleases(releasedContainers);
// Assuming the ApplicationMaster can track its progress
req.setProgress(currentProgress);
AllocateResponse allocateResponse = resourceManager.allocate(req); ResourceManager返回的AllocateResponse通过AMResponse对象包含了下面这些信息：
- Reboot flag：如果ApplicationMaster失去了和ResourceManager同步，则需要reboot
- Allocated containers：分配给ApplicationMaster的containers
- Headroom：整个机群的余量资源，基于这个信息和自己的资源需求，ApplicationMaster可以智能的决定调整子任务的优先度利用已经获得的containers，或者如果没有可获得的resource时，能够快速的脱困。
- Completed containers：当ApplicationMaster启动了一个获得的container后，当这个container完成后，它将接收到来自ResourceManager的更新信息。ApplicationMaster能够查看完成的container的状态信息，采取适当的行动，比如如果任务失败则重试执行。
// Get AMResponse from AllocateResponse
AMResponse amResp = allocateResponse.getAMResponse();
// Retrieve list of allocated containers from the response
// and on each allocated container, lets assume we are launching
// the same job.
List<Container> allocatedContainers = amResp.getAllocatedContainers();
for (Container allocatedContainer : allocatedContainers) {
LOG.info("Launching shell command on a new container."
+ ", containerId=" + allocatedContainer.getId()
+ ", containerNode=" + allocatedContainer.getNodeId().getHost()
+ ":" + allocatedContainer.getNodeId().getPort()
+ ", containerNodeURI=" + allocatedContainer.getNodeHttpAddress()
+ ", containerState" + allocatedContainer.getState()
+ ", containerResourceMemory"
+ allocatedContainer.getResource().getMemory());
// Launch and start the container on a separate thread to keep the main
// thread unblocked as all containers may not be allocated at one go.
LaunchContainerRunnable runnableLaunchContainer =
new LaunchContainerRunnable(allocatedContainer);
Thread launchThread = new Thread(runnableLaunchContainer);
launchThreads.add(launchThread);
launchThread.start();
}
// Check what the current available resources in the cluster are
Resource availableResources = amResp.getAvailableResources();
// Based on this information, an ApplicationMaster can make appropriate
// decisions
// Check the completed containers
// Let's assume we are keeping a count of total completed containers,
// containers that failed and ones that completed successfully.
List<ContainerStatus> completedContainers =
amResp.getCompletedContainersStatuses();
for (ContainerStatus containerStatus : completedContainers) {
LOG.info("Got container status for containerID= "
+ containerStatus.getContainerId()
+ ", state=" + containerStatus.getState()
+ ", exitStatus=" + containerStatus.getExitStatus()
+ ", diagnostics=" + containerStatus.getDiagnostics());
int exitStatus = containerStatus.getExitStatus();
if (0 != exitStatus) {
// container failed
// -100 is a special case where the container
// was aborted/pre-empted for some reason
if (-100 != exitStatus) {
// application job on container returned a non-zero exit code
// counts as completed
numCompletedContainers.incrementAndGet();
numFailedContainers.incrementAndGet();
}
else {
// something else bad happened
// app job did not complete for some reason
// we should re-try as the container was lost for some reason
// decrementing the requested count so that we ask for an
// additional one in the next allocate call.
numRequestedContainers.decrementAndGet();
// we do not need to release the container as that has already
// been done by the ResourceManager/NodeManager.
}
}
else {
// nothing to do
// container completed successfully
numCompletedContainers.incrementAndGet();
numSuccessfulContainers.incrementAndGet();
}
}
}当container分配给ApplicationMaster以后，ApplicationMaster需要follow Client相似的过程来为最终的task设置ContainerLaunchContext，使得task能够在获取到的container上运行。一旦ContainerLaunchContext被定义了，ApplicationMaster能够与ContainerManager进行通信启动这个allocated container。
//Assuming an allocated Container obtained from AMResponse
Container container;
// Connect to ContainerManager on the allocated container
String cmIpPortStr = container.getNodeId().getHost() + ":"
+ container.getNodeId().getPort();
InetSocketAddress cmAddress = NetUtils.createSocketAddr(cmIpPortStr);
ContainerManager cm =
(ContainerManager)rpc.getProxy(ContainerManager.class, cmAddress, conf);
// Now we setup a ContainerLaunchContext
ContainerLaunchContext ctx =
Records.newRecord(ContainerLaunchContext.class);
ctx.setContainerId(container.getId());
ctx.setResource(container.getResource());
try {
ctx.setUser(UserGroupInformation.getCurrentUser().getShortUserName());
} catch (IOException e) {
LOG.info(
"Getting current user failed when trying to launch the container",
+ e.getMessage());
}
// Set the environment
Map<String, String> unixEnv;
// Setup the required env.
// Please note that the launched container does not inherit
// the environment of the ApplicationMaster so all the
// necessary environment settings will need to be re-setup
// for this allocated container.
ctx.setEnvironment(unixEnv);
// Set the local resources
Map<String, LocalResource> localResources =
new HashMap<String, LocalResource>();
// Again, the local resources from the ApplicationMaster is not copied over
// by default to the allocated container. Thus, it is the responsibility
// of the ApplicationMaster to setup all the necessary local resources
// needed by the job that will be executed on the allocated container.
// Assume that we are executing a shell script on the allocated container
// and the shell script's location in the filesystem is known to us.
Path shellScriptPath;
LocalResource shellRsrc = Records.newRecord(LocalResource.class);
shellRsrc.setType(LocalResourceType.FILE);
shellRsrc.setVisibility(LocalResourceVisibility.APPLICATION);
shellRsrc.setResource(
ConverterUtils.getYarnUrlFromURI(new URI(shellScriptPath)));
shellRsrc.setTimestamp(shellScriptPathTimestamp);
shellRsrc.setSize(shellScriptPathLen);
localResources.put("MyExecShell.sh", shellRsrc);
ctx.setLocalResources(localResources);
// Set the necessary command to execute on the allocated container
String command = "/bin/sh ./MyExecShell.sh"
+ " 1>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stdout"
+ " 2>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stderr";
List<String> commands = new ArrayList<String>();
commands.add(command);
ctx.setCommands(commands);
// Send the start request to the ContainerManager
StartContainerRequest startReq = Records.newRecord(StartContainerRequest.class);
startReq.setContainerLaunchContext(ctx);
cm.startContainer(startReq);正如前面所描述的，通过AMRMProtocol::allocate调用的返回信息，ApplicationMaster能够得到完成情况的更新信息，他也能够通过查询ContainerManager的状态来主动监测launched container。
GetContainerStatusRequest statusReq =
Records.newRecord(GetContainerStatusRequest.class);
statusReq.setContainerId(container.getId());
GetContainerStatusResponse statusResp = cm.getContainerStatus(statusReq);
LOG.info("Container Status"
+ ", id=" + container.getId()
+ ", status=" + statusResp.getStatus());FAQ
1、我如何能够将我的application的jars部署到需要这些jars的全部的节点上？
你可以利用LocalResource将需要的resource添加进去。这将使YARN分发这些资源到ApplicationMaster node。如果资源类型是tgz，zip或者jar，你可以让YARN去unzip他们。你需要做的只是将unziped的folder添加到你的classpath中。举例来说，当你像下面这样创建你的application request：
File packageFile = new File(packagePath);
Url packageUrl = ConverterUtils.getYarnUrlFromPath(
FileContext.getFileContext.makeQualified(new Path(packagePath)));
packageResource.setResource(packageUrl);
packageResource.setSize(packageFile.length());
packageResource.setTimestamp(packageFile.lastModified());
packageResource.setType(LocalResourceType.ARCHIVE);
packageResource.setVisibility(LocalResourceVisibility.APPLICATION);
resource.setMemory(memory)
containerCtx.setResource(resource)
containerCtx.setCommands(ImmutableList.of(
"java -cp './package/*' some.class.to.Run "
+ "1>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stdout "
+ "2>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/stderr"))
containerCtx.setLocalResources(
Collections.singletonMap("package", packageResource))
appCtx.setApplicationId(appId)
appCtx.setUser(user.getShortUserName)
appCtx.setAMContainerSpec(containerCtx)
request.setApplicationSubmissionContext(appCtx)
applicationsManager.submitApplication(request)正如你所看到的，setLocalResource命令通过一个map建立了names和resources的映射，name成为一个sym链接进入你应用的cwd，因此通过使用“./package*."，你就可以使用这些设施了（artifacts）
注意：Java‘s classpath参数是非常sensitive的，一定要保证你使用的语法正确。
一旦你的package被部署到你的ApplicationMaster，无论何时ApplicationMaster启动一个新的container，你只要follow这个相同的过程（假设你希望resource被发送到你的container）。这段代码是完全相同的，你只要确信你给你的ApplicationMaster package path（无论是HDFS或者local），这样它可以随着container的ctx一起发送resource URL。
2、我如何获得ApplicationMaster的ApplicationAttemptId？
通过环境变量，ApplicationAttemptId将被发送给ApplicationMaster，从环境变量获得的值通过ConverterUtils辅助函数能够转化为ApplicationAttemptId对象。
3、我的container被NodeManager kill了
这可能是因为比较高的内存消耗超出了你的container的memory size。有一系列的原因可能产生这种现象，首先当container被kill时，可以产看node manager dump出来的process tree。你需要关注的是physical memory和virtual memory。如果你超出了physical memory限制，你的application使用了太多的physical memory，如果你运行一个Java app，你可以使用 -hprof来什么占用了堆里的空间。如果你超出了虚拟内存的限制，你需要增加机群范围的配置变量yarn.nodemanager.vmem-pmem-ratio.
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