001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.yarn.applications.distributedshell;
020    
021    import java.io.BufferedReader;
022    import java.io.IOException;
023    import java.io.InputStream;
024    import java.io.InputStreamReader;
025    import java.util.ArrayList;
026    import java.util.HashMap;
027    import java.util.List;
028    import java.util.Map;
029    import java.util.Vector;
030    
031    import org.apache.commons.cli.CommandLine;
032    import org.apache.commons.cli.GnuParser;
033    import org.apache.commons.cli.HelpFormatter;
034    import org.apache.commons.cli.Options;
035    import org.apache.commons.cli.ParseException;
036    import org.apache.commons.logging.Log;
037    import org.apache.commons.logging.LogFactory;
038    import org.apache.hadoop.classification.InterfaceAudience;
039    import org.apache.hadoop.classification.InterfaceStability;
040    import org.apache.hadoop.conf.Configuration;
041    import org.apache.hadoop.fs.FileStatus;
042    import org.apache.hadoop.fs.FileSystem;
043    import org.apache.hadoop.fs.Path;
044    import org.apache.hadoop.yarn.api.ApplicationConstants;
045    import org.apache.hadoop.yarn.api.ClientRMProtocol;
046    import org.apache.hadoop.yarn.api.protocolrecords.GetNewApplicationResponse;
047    import org.apache.hadoop.yarn.api.protocolrecords.KillApplicationRequest;
048    import org.apache.hadoop.yarn.api.records.ApplicationId;
049    import org.apache.hadoop.yarn.api.records.ApplicationReport;
050    import org.apache.hadoop.yarn.api.records.ApplicationSubmissionContext;
051    import org.apache.hadoop.yarn.api.records.ContainerLaunchContext;
052    import org.apache.hadoop.yarn.api.records.FinalApplicationStatus;
053    import org.apache.hadoop.yarn.api.records.LocalResource;
054    import org.apache.hadoop.yarn.api.records.LocalResourceType;
055    import org.apache.hadoop.yarn.api.records.LocalResourceVisibility;
056    import org.apache.hadoop.yarn.api.records.NodeReport;
057    import org.apache.hadoop.yarn.api.records.Priority;
058    import org.apache.hadoop.yarn.api.records.QueueACL;
059    import org.apache.hadoop.yarn.api.records.QueueInfo;
060    import org.apache.hadoop.yarn.api.records.QueueUserACLInfo;
061    import org.apache.hadoop.yarn.api.records.Resource;
062    import org.apache.hadoop.yarn.api.records.YarnApplicationState;
063    import org.apache.hadoop.yarn.api.records.YarnClusterMetrics;
064    import org.apache.hadoop.yarn.client.YarnClientImpl;
065    import org.apache.hadoop.yarn.conf.YarnConfiguration;
066    import org.apache.hadoop.yarn.exceptions.YarnRemoteException;
067    import org.apache.hadoop.yarn.util.ConverterUtils;
068    import org.apache.hadoop.yarn.util.Records;
069    
070    /**
071     * Client for Distributed Shell application submission to YARN.
072     * 
073     * <p> The distributed shell client allows an application master to be launched that in turn would run 
074     * the provided shell command on a set of containers. </p>
075     * 
076     * <p>This client is meant to act as an example on how to write yarn-based applications. </p>
077     * 
078     * <p> To submit an application, a client first needs to connect to the <code>ResourceManager</code> 
079     * aka ApplicationsManager or ASM via the {@link ClientRMProtocol}. The {@link ClientRMProtocol} 
080     * provides a way for the client to get access to cluster information and to request for a
081     * new {@link ApplicationId}. <p>
082     * 
083     * <p> For the actual job submission, the client first has to create an {@link ApplicationSubmissionContext}. 
084     * The {@link ApplicationSubmissionContext} defines the application details such as {@link ApplicationId} 
085     * and application name, user submitting the application, the priority assigned to the application and the queue 
086     * to which this application needs to be assigned. In addition to this, the {@link ApplicationSubmissionContext}
087     * also defines the {@link ContainerLaunchContext} which describes the <code>Container</code> with which 
088     * the {@link ApplicationMaster} is launched. </p>
089     * 
090     * <p> The {@link ContainerLaunchContext} in this scenario defines the resources to be allocated for the 
091     * {@link ApplicationMaster}'s container, the local resources (jars, configuration files) to be made available 
092     * and the environment to be set for the {@link ApplicationMaster} and the commands to be executed to run the 
093     * {@link ApplicationMaster}. <p>
094     * 
095     * <p> Using the {@link ApplicationSubmissionContext}, the client submits the application to the 
096     * <code>ResourceManager</code> and then monitors the application by requesting the <code>ResourceManager</code> 
097     * for an {@link ApplicationReport} at regular time intervals. In case of the application taking too long, the client 
098     * kills the application by submitting a {@link KillApplicationRequest} to the <code>ResourceManager</code>. </p>
099     *
100     */
101    @InterfaceAudience.Public
102    @InterfaceStability.Unstable
103    public class Client extends YarnClientImpl {
104    
105      private static final Log LOG = LogFactory.getLog(Client.class);
106    
107      // Configuration
108      private Configuration conf;
109    
110      // Application master specific info to register a new Application with RM/ASM
111      private String appName = "";
112      // App master priority
113      private int amPriority = 0;
114      // Queue for App master
115      private String amQueue = "";
116      // User to run app master as
117      private String amUser = "";
118      // Amt. of memory resource to request for to run the App Master
119      private int amMemory = 10; 
120    
121      // Application master jar file
122      private String appMasterJar = ""; 
123      // Main class to invoke application master
124      private String appMasterMainClass = "";
125    
126      // Shell command to be executed 
127      private String shellCommand = ""; 
128      // Location of shell script 
129      private String shellScriptPath = ""; 
130      // Args to be passed to the shell command
131      private String shellArgs = "";
132      // Env variables to be setup for the shell command 
133      private Map<String, String> shellEnv = new HashMap<String, String>();
134      // Shell Command Container priority 
135      private int shellCmdPriority = 0;
136    
137      // Amt of memory to request for container in which shell script will be executed
138      private int containerMemory = 10; 
139      // No. of containers in which the shell script needs to be executed
140      private int numContainers = 1;
141    
142      // log4j.properties file 
143      // if available, add to local resources and set into classpath 
144      private String log4jPropFile = "";    
145    
146      // Start time for client
147      private final long clientStartTime = System.currentTimeMillis();
148      // Timeout threshold for client. Kill app after time interval expires.
149      private long clientTimeout = 600000;
150    
151      // Debug flag
152      boolean debugFlag = false;    
153    
154      /**
155       * @param args Command line arguments 
156       */
157      public static void main(String[] args) {
158        boolean result = false;
159        try {
160          Client client = new Client();
161          LOG.info("Initializing Client");
162          boolean doRun = client.init(args);
163          if (!doRun) {
164            System.exit(0);
165          }
166          result = client.run();
167        } catch (Throwable t) {
168          LOG.fatal("Error running CLient", t);
169          System.exit(1);
170        }
171        if (result) {
172          LOG.info("Application completed successfully");
173          System.exit(0);                   
174        } 
175        LOG.error("Application failed to complete successfully");
176        System.exit(2);
177      }
178    
179      /**
180       */
181      public Client(Configuration conf) throws Exception  {
182        super();
183        this.conf = conf;
184        init(conf);
185      }
186    
187      /**
188       */
189      public Client() throws Exception  {
190        this(new Configuration());
191      }
192    
193      /**
194       * Helper function to print out usage
195       * @param opts Parsed command line options 
196       */
197      private void printUsage(Options opts) {
198        new HelpFormatter().printHelp("Client", opts);
199      }
200    
201      /**
202       * Parse command line options
203       * @param args Parsed command line options 
204       * @return Whether the init was successful to run the client
205       */
206      public boolean init(String[] args) throws ParseException {
207    
208        Options opts = new Options();
209        opts.addOption("appname", true, "Application Name. Default value - DistributedShell");
210        opts.addOption("priority", true, "Application Priority. Default 0");
211        opts.addOption("queue", true, "RM Queue in which this application is to be submitted");
212        opts.addOption("user", true, "User to run the application as");
213        opts.addOption("timeout", true, "Application timeout in milliseconds");
214        opts.addOption("master_memory", true, "Amount of memory in MB to be requested to run the application master");
215        opts.addOption("jar", true, "Jar file containing the application master");
216        opts.addOption("class", true, "Main class to  be run for the Application Master.");
217        opts.addOption("shell_command", true, "Shell command to be executed by the Application Master");
218        opts.addOption("shell_script", true, "Location of the shell script to be executed");
219        opts.addOption("shell_args", true, "Command line args for the shell script");
220        opts.addOption("shell_env", true, "Environment for shell script. Specified as env_key=env_val pairs");
221        opts.addOption("shell_cmd_priority", true, "Priority for the shell command containers");            
222        opts.addOption("container_memory", true, "Amount of memory in MB to be requested to run the shell command");
223        opts.addOption("num_containers", true, "No. of containers on which the shell command needs to be executed");
224        opts.addOption("log_properties", true, "log4j.properties file");
225        opts.addOption("debug", false, "Dump out debug information");
226        opts.addOption("help", false, "Print usage");
227        CommandLine cliParser = new GnuParser().parse(opts, args);
228    
229        if (args.length == 0) {
230          printUsage(opts);
231          throw new IllegalArgumentException("No args specified for client to initialize");
232        }           
233    
234        if (cliParser.hasOption("help")) {
235          printUsage(opts);
236          return false;
237        }
238    
239        if (cliParser.hasOption("debug")) {
240          debugFlag = true;
241    
242        }
243    
244        appName = cliParser.getOptionValue("appname", "DistributedShell");
245        amPriority = Integer.parseInt(cliParser.getOptionValue("priority", "0"));
246        amQueue = cliParser.getOptionValue("queue", "");
247        amUser = cliParser.getOptionValue("user", "");
248        amMemory = Integer.parseInt(cliParser.getOptionValue("master_memory", "10"));               
249    
250        if (amMemory < 0) {
251          throw new IllegalArgumentException("Invalid memory specified for application master, exiting."
252              + " Specified memory=" + amMemory);
253        }
254    
255        if (!cliParser.hasOption("jar")) {
256          throw new IllegalArgumentException("No jar file specified for application master");
257        }           
258    
259        appMasterJar = cliParser.getOptionValue("jar");
260        appMasterMainClass = cliParser.getOptionValue("class",
261            "org.apache.hadoop.yarn.applications.distributedshell.ApplicationMaster");              
262    
263        if (!cliParser.hasOption("shell_command")) {
264          throw new IllegalArgumentException("No shell command specified to be executed by application master");
265        }
266        shellCommand = cliParser.getOptionValue("shell_command");
267    
268        if (cliParser.hasOption("shell_script")) {
269          shellScriptPath = cliParser.getOptionValue("shell_script");
270        }
271        if (cliParser.hasOption("shell_args")) {
272          shellArgs = cliParser.getOptionValue("shell_args");
273        }
274        if (cliParser.hasOption("shell_env")) { 
275          String envs[] = cliParser.getOptionValues("shell_env");
276          for (String env : envs) {
277            env = env.trim();
278            int index = env.indexOf('=');
279            if (index == -1) {
280              shellEnv.put(env, "");
281              continue;
282            }
283            String key = env.substring(0, index);
284            String val = "";
285            if (index < (env.length()-1)) {
286              val = env.substring(index+1);
287            }
288            shellEnv.put(key, val);
289          }
290        }
291        shellCmdPriority = Integer.parseInt(cliParser.getOptionValue("shell_cmd_priority", "0"));
292    
293        containerMemory = Integer.parseInt(cliParser.getOptionValue("container_memory", "10"));
294        numContainers = Integer.parseInt(cliParser.getOptionValue("num_containers", "1"));
295    
296        if (containerMemory < 0 || numContainers < 1) {
297          throw new IllegalArgumentException("Invalid no. of containers or container memory specified, exiting."
298              + " Specified containerMemory=" + containerMemory
299              + ", numContainer=" + numContainers);
300        }
301    
302        clientTimeout = Integer.parseInt(cliParser.getOptionValue("timeout", "600000"));
303    
304        log4jPropFile = cliParser.getOptionValue("log_properties", "");
305    
306        return true;
307      }
308    
309      /**
310       * Main run function for the client
311       * @return true if application completed successfully
312       * @throws IOException
313       */
314      public boolean run() throws IOException {
315    
316        LOG.info("Running Client");
317        start();
318    
319        YarnClusterMetrics clusterMetrics = super.getYarnClusterMetrics();
320        LOG.info("Got Cluster metric info from ASM" 
321            + ", numNodeManagers=" + clusterMetrics.getNumNodeManagers());
322    
323        List<NodeReport> clusterNodeReports = super.getNodeReports();
324        LOG.info("Got Cluster node info from ASM");
325        for (NodeReport node : clusterNodeReports) {
326          LOG.info("Got node report from ASM for"
327              + ", nodeId=" + node.getNodeId() 
328              + ", nodeAddress" + node.getHttpAddress()
329              + ", nodeRackName" + node.getRackName()
330              + ", nodeNumContainers" + node.getNumContainers()
331              + ", nodeHealthStatus" + node.getNodeHealthStatus());
332        }
333    
334        QueueInfo queueInfo = super.getQueueInfo(this.amQueue);             
335        LOG.info("Queue info"
336            + ", queueName=" + queueInfo.getQueueName()
337            + ", queueCurrentCapacity=" + queueInfo.getCurrentCapacity()
338            + ", queueMaxCapacity=" + queueInfo.getMaximumCapacity()
339            + ", queueApplicationCount=" + queueInfo.getApplications().size()
340            + ", queueChildQueueCount=" + queueInfo.getChildQueues().size());               
341    
342        List<QueueUserACLInfo> listAclInfo = super.getQueueAclsInfo();                                
343        for (QueueUserACLInfo aclInfo : listAclInfo) {
344          for (QueueACL userAcl : aclInfo.getUserAcls()) {
345            LOG.info("User ACL Info for Queue"
346                + ", queueName=" + aclInfo.getQueueName()                   
347                + ", userAcl=" + userAcl.name());
348          }
349        }           
350    
351        // Get a new application id 
352        GetNewApplicationResponse newApp = super.getNewApplication();
353        ApplicationId appId = newApp.getApplicationId();
354    
355        // TODO get min/max resource capabilities from RM and change memory ask if needed
356        // If we do not have min/max, we may not be able to correctly request 
357        // the required resources from the RM for the app master
358        // Memory ask has to be a multiple of min and less than max. 
359        // Dump out information about cluster capability as seen by the resource manager
360        int minMem = newApp.getMinimumResourceCapability().getMemory();
361        int maxMem = newApp.getMaximumResourceCapability().getMemory();
362        LOG.info("Min mem capabililty of resources in this cluster " + minMem);
363        LOG.info("Max mem capabililty of resources in this cluster " + maxMem);
364    
365        // A resource ask has to be atleast the minimum of the capability of the cluster, the value has to be 
366        // a multiple of the min value and cannot exceed the max. 
367        // If it is not an exact multiple of min, the RM will allocate to the nearest multiple of min
368        if (amMemory < minMem) {
369          LOG.info("AM memory specified below min threshold of cluster. Using min value."
370              + ", specified=" + amMemory
371              + ", min=" + minMem);
372          amMemory = minMem; 
373        } 
374        else if (amMemory > maxMem) {
375          LOG.info("AM memory specified above max threshold of cluster. Using max value."
376              + ", specified=" + amMemory
377              + ", max=" + maxMem);
378          amMemory = maxMem;
379        }                           
380    
381        // Create launch context for app master
382        LOG.info("Setting up application submission context for ASM");
383        ApplicationSubmissionContext appContext = Records.newRecord(ApplicationSubmissionContext.class);
384    
385        // set the application id 
386        appContext.setApplicationId(appId);
387        // set the application name
388        appContext.setApplicationName(appName);
389    
390        // Set up the container launch context for the application master
391        ContainerLaunchContext amContainer = Records.newRecord(ContainerLaunchContext.class);
392    
393        // set local resources for the application master
394        // local files or archives as needed
395        // In this scenario, the jar file for the application master is part of the local resources                 
396        Map<String, LocalResource> localResources = new HashMap<String, LocalResource>();
397    
398        LOG.info("Copy App Master jar from local filesystem and add to local environment");
399        // Copy the application master jar to the filesystem 
400        // Create a local resource to point to the destination jar path 
401        FileSystem fs = FileSystem.get(conf);
402        Path src = new Path(appMasterJar);
403        String pathSuffix = appName + "/" + appId.getId() + "/AppMaster.jar";           
404        Path dst = new Path(fs.getHomeDirectory(), pathSuffix);
405        fs.copyFromLocalFile(false, true, src, dst);
406        FileStatus destStatus = fs.getFileStatus(dst);
407        LocalResource amJarRsrc = Records.newRecord(LocalResource.class);
408    
409        // Set the type of resource - file or archive
410        // archives are untarred at destination
411        // we don't need the jar file to be untarred for now
412        amJarRsrc.setType(LocalResourceType.FILE);
413        // Set visibility of the resource 
414        // Setting to most private option
415        amJarRsrc.setVisibility(LocalResourceVisibility.APPLICATION);          
416        // Set the resource to be copied over
417        amJarRsrc.setResource(ConverterUtils.getYarnUrlFromPath(dst)); 
418        // Set timestamp and length of file so that the framework 
419        // can do basic sanity checks for the local resource 
420        // after it has been copied over to ensure it is the same 
421        // resource the client intended to use with the application
422        amJarRsrc.setTimestamp(destStatus.getModificationTime());
423        amJarRsrc.setSize(destStatus.getLen());
424        localResources.put("AppMaster.jar",  amJarRsrc);
425    
426        // Set the log4j properties if needed 
427        if (!log4jPropFile.isEmpty()) {
428          Path log4jSrc = new Path(log4jPropFile);
429          Path log4jDst = new Path(fs.getHomeDirectory(), "log4j.props");
430          fs.copyFromLocalFile(false, true, log4jSrc, log4jDst);
431          FileStatus log4jFileStatus = fs.getFileStatus(log4jDst);
432          LocalResource log4jRsrc = Records.newRecord(LocalResource.class);
433          log4jRsrc.setType(LocalResourceType.FILE);
434          log4jRsrc.setVisibility(LocalResourceVisibility.APPLICATION);        
435          log4jRsrc.setResource(ConverterUtils.getYarnUrlFromURI(log4jDst.toUri()));
436          log4jRsrc.setTimestamp(log4jFileStatus.getModificationTime());
437          log4jRsrc.setSize(log4jFileStatus.getLen());
438          localResources.put("log4j.properties", log4jRsrc);
439        }                   
440    
441        // The shell script has to be made available on the final container(s)
442        // where it will be executed. 
443        // To do this, we need to first copy into the filesystem that is visible 
444        // to the yarn framework. 
445        // We do not need to set this as a local resource for the application 
446        // master as the application master does not need it.               
447        String hdfsShellScriptLocation = ""; 
448        long hdfsShellScriptLen = 0;
449        long hdfsShellScriptTimestamp = 0;
450        if (!shellScriptPath.isEmpty()) {
451          Path shellSrc = new Path(shellScriptPath);
452          String shellPathSuffix = appName + "/" + appId.getId() + "/ExecShellScript.sh";
453          Path shellDst = new Path(fs.getHomeDirectory(), shellPathSuffix);
454          fs.copyFromLocalFile(false, true, shellSrc, shellDst);
455          hdfsShellScriptLocation = shellDst.toUri().toString(); 
456          FileStatus shellFileStatus = fs.getFileStatus(shellDst);
457          hdfsShellScriptLen = shellFileStatus.getLen();
458          hdfsShellScriptTimestamp = shellFileStatus.getModificationTime();
459        }
460    
461        // Set local resource info into app master container launch context
462        amContainer.setLocalResources(localResources);
463    
464        // Set the necessary security tokens as needed
465        //amContainer.setContainerTokens(containerToken);
466    
467        // Set the env variables to be setup in the env where the application master will be run
468        LOG.info("Set the environment for the application master");
469        Map<String, String> env = new HashMap<String, String>();
470    
471        // put location of shell script into env
472        // using the env info, the application master will create the correct local resource for the 
473        // eventual containers that will be launched to execute the shell scripts
474        env.put(DSConstants.DISTRIBUTEDSHELLSCRIPTLOCATION, hdfsShellScriptLocation);
475        env.put(DSConstants.DISTRIBUTEDSHELLSCRIPTTIMESTAMP, Long.toString(hdfsShellScriptTimestamp));
476        env.put(DSConstants.DISTRIBUTEDSHELLSCRIPTLEN, Long.toString(hdfsShellScriptLen));
477    
478        // Add AppMaster.jar location to classpath          
479        // At some point we should not be required to add 
480        // the hadoop specific classpaths to the env. 
481        // It should be provided out of the box. 
482        // For now setting all required classpaths including
483        // the classpath to "." for the application jar
484        StringBuilder classPathEnv = new StringBuilder("${CLASSPATH}:./*");
485        for (String c : conf.get(YarnConfiguration.YARN_APPLICATION_CLASSPATH)
486            .split(",")) {
487          classPathEnv.append(':');
488          classPathEnv.append(c.trim());
489        }
490        classPathEnv.append(":./log4j.properties");
491    
492        // add the runtime classpath needed for tests to work
493        String testRuntimeClassPath = Client.getTestRuntimeClasspath();
494        classPathEnv.append(':');
495        classPathEnv.append(testRuntimeClassPath);
496    
497        env.put("CLASSPATH", classPathEnv.toString());
498    
499        amContainer.setEnvironment(env);
500    
501        // Set the necessary command to execute the application master 
502        Vector<CharSequence> vargs = new Vector<CharSequence>(30);
503    
504        // Set java executable command 
505        LOG.info("Setting up app master command");
506        vargs.add("${JAVA_HOME}" + "/bin/java");
507        // Set Xmx based on am memory size
508        vargs.add("-Xmx" + amMemory + "m");
509        // Set class name 
510        vargs.add(appMasterMainClass);
511        // Set params for Application Master
512        vargs.add("--container_memory " + String.valueOf(containerMemory));
513        vargs.add("--num_containers " + String.valueOf(numContainers));
514        vargs.add("--priority " + String.valueOf(shellCmdPriority));
515        if (!shellCommand.isEmpty()) {
516          vargs.add("--shell_command " + shellCommand + "");
517        }
518        if (!shellArgs.isEmpty()) {
519          vargs.add("--shell_args " + shellArgs + "");
520        }
521        for (Map.Entry<String, String> entry : shellEnv.entrySet()) {
522          vargs.add("--shell_env " + entry.getKey() + "=" + entry.getValue());
523        }                   
524        if (debugFlag) {
525          vargs.add("--debug");
526        }
527    
528        vargs.add("1>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/AppMaster.stdout");
529        vargs.add("2>" + ApplicationConstants.LOG_DIR_EXPANSION_VAR + "/AppMaster.stderr");
530    
531        // Get final commmand
532        StringBuilder command = new StringBuilder();
533        for (CharSequence str : vargs) {
534          command.append(str).append(" ");
535        }
536    
537        LOG.info("Completed setting up app master command " + command.toString());     
538        List<String> commands = new ArrayList<String>();
539        commands.add(command.toString());           
540        amContainer.setCommands(commands);
541    
542        // For launching an AM Container, setting user here is not needed
543        // Set user in ApplicationSubmissionContext
544        // amContainer.setUser(amUser);
545    
546        // Set up resource type requirements
547        // For now, only memory is supported so we set memory requirements
548        Resource capability = Records.newRecord(Resource.class);
549        capability.setMemory(amMemory);
550        amContainer.setResource(capability);
551    
552        // Service data is a binary blob that can be passed to the application
553        // Not needed in this scenario
554        // amContainer.setServiceData(serviceData);
555    
556        // The following are not required for launching an application master 
557        // amContainer.setContainerId(containerId);         
558    
559        appContext.setAMContainerSpec(amContainer);
560    
561        // Set the priority for the application master
562        Priority pri = Records.newRecord(Priority.class);
563        // TODO - what is the range for priority? how to decide? 
564        pri.setPriority(amPriority);
565        appContext.setPriority(pri);
566    
567        // Set the queue to which this application is to be submitted in the RM
568        appContext.setQueue(amQueue);
569        // Set the user submitting this application 
570        // TODO can it be empty? 
571        appContext.setUser(amUser);
572    
573        // Submit the application to the applications manager
574        // SubmitApplicationResponse submitResp = applicationsManager.submitApplication(appRequest);
575        // Ignore the response as either a valid response object is returned on success 
576        // or an exception thrown to denote some form of a failure
577        LOG.info("Submitting application to ASM");
578        super.submitApplication(appContext);
579    
580        // TODO
581        // Try submitting the same request again
582        // app submission failure?
583    
584        // Monitor the application
585        return monitorApplication(appId);
586    
587      }
588    
589      /**
590       * Monitor the submitted application for completion. 
591       * Kill application if time expires. 
592       * @param appId Application Id of application to be monitored
593       * @return true if application completed successfully
594       * @throws YarnRemoteException
595       */
596      private boolean monitorApplication(ApplicationId appId) throws YarnRemoteException {
597    
598        while (true) {
599    
600          // Check app status every 1 second.
601          try {
602            Thread.sleep(1000);
603          } catch (InterruptedException e) {
604            LOG.debug("Thread sleep in monitoring loop interrupted");
605          }
606    
607          // Get application report for the appId we are interested in 
608          ApplicationReport report = super.getApplicationReport(appId);
609    
610          LOG.info("Got application report from ASM for"
611              + ", appId=" + appId.getId()
612              + ", clientToken=" + report.getClientToken()
613              + ", appDiagnostics=" + report.getDiagnostics()
614              + ", appMasterHost=" + report.getHost()
615              + ", appQueue=" + report.getQueue()
616              + ", appMasterRpcPort=" + report.getRpcPort()
617              + ", appStartTime=" + report.getStartTime()
618              + ", yarnAppState=" + report.getYarnApplicationState().toString()
619              + ", distributedFinalState=" + report.getFinalApplicationStatus().toString()
620              + ", appTrackingUrl=" + report.getTrackingUrl()
621              + ", appUser=" + report.getUser());
622    
623          YarnApplicationState state = report.getYarnApplicationState();
624          FinalApplicationStatus dsStatus = report.getFinalApplicationStatus();
625          if (YarnApplicationState.FINISHED == state) {
626            if (FinalApplicationStatus.SUCCEEDED == dsStatus) {
627              LOG.info("Application has completed successfully. Breaking monitoring loop");
628              return true;        
629            }
630            else {
631              LOG.info("Application did finished unsuccessfully."
632                  + " YarnState=" + state.toString() + ", DSFinalStatus=" + dsStatus.toString()
633                  + ". Breaking monitoring loop");
634              return false;
635            }                         
636          }
637          else if (YarnApplicationState.KILLED == state     
638              || YarnApplicationState.FAILED == state) {
639            LOG.info("Application did not finish."
640                + " YarnState=" + state.toString() + ", DSFinalStatus=" + dsStatus.toString()
641                + ". Breaking monitoring loop");
642            return false;
643          }                 
644    
645          if (System.currentTimeMillis() > (clientStartTime + clientTimeout)) {
646            LOG.info("Reached client specified timeout for application. Killing application");
647            forceKillApplication(appId);
648            return false;                           
649          }
650        }                   
651    
652      }
653    
654      /**
655       * Kill a submitted application by sending a call to the ASM
656       * @param appId Application Id to be killed. 
657       * @throws YarnRemoteException
658       */
659      private void forceKillApplication(ApplicationId appId) throws YarnRemoteException {
660        // TODO clarify whether multiple jobs with the same app id can be submitted and be running at 
661        // the same time. 
662        // If yes, can we kill a particular attempt only?
663    
664        // Response can be ignored as it is non-null on success or 
665        // throws an exception in case of failures
666        super.killApplication(appId);       
667      }
668    
669      private static String getTestRuntimeClasspath() {
670    
671        InputStream classpathFileStream = null;
672        BufferedReader reader = null;
673        String envClassPath = "";
674    
675        LOG.info("Trying to generate classpath for app master from current thread's classpath");
676        try {
677    
678          // Create classpath from generated classpath
679          // Check maven ppom.xml for generated classpath info
680          // Works if compile time env is same as runtime. Mainly tests.
681          ClassLoader thisClassLoader =
682              Thread.currentThread().getContextClassLoader();
683          String generatedClasspathFile = "yarn-apps-ds-generated-classpath";
684          classpathFileStream =
685              thisClassLoader.getResourceAsStream(generatedClasspathFile);
686          if (classpathFileStream == null) {
687            LOG.info("Could not classpath resource from class loader");
688            return envClassPath;
689          }
690          LOG.info("Readable bytes from stream=" + classpathFileStream.available());
691          reader = new BufferedReader(new InputStreamReader(classpathFileStream));
692          String cp = reader.readLine();
693          if (cp != null) {
694            envClassPath += cp.trim() + ":";
695          }
696          // Put the file itself on classpath for tasks.
697          envClassPath += thisClassLoader.getResource(generatedClasspathFile).getFile();
698        } catch (IOException e) {
699          LOG.info("Could not find the necessary resource to generate class path for tests. Error=" + e.getMessage());
700        } 
701    
702        try {
703          if (classpathFileStream != null) {
704            classpathFileStream.close();
705          }
706          if (reader != null) {
707            reader.close();
708          }
709        } catch (IOException e) {
710          LOG.info("Failed to close class path file stream or reader. Error=" + e.getMessage());
711        } 
712        return envClassPath;
713      }                     
714    
715    }