MAPREDUCE-6824. TaskAttemptImpl#createCommonContainerLaunchContext is longer than 150 lines. Contributed by Chris Trezzo.

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/TaskAttemptImpl.java

@@ -755,7 +755,7 @@ private static ContainerLaunchContext createCommonContainerLaunchContext(
         new HashMap<String, LocalResource>();
     
     // Application environment
-    Map<String, String> environment = new HashMap<String, String>();
+    Map<String, String> environment;
 
     // Service data
     Map<String, ByteBuffer> serviceData = new HashMap<String, ByteBuffer>();
@@ -763,9 +763,65 @@ private static ContainerLaunchContext createCommonContainerLaunchContext(
     // Tokens
     ByteBuffer taskCredentialsBuffer = ByteBuffer.wrap(new byte[]{});
     try {
-      FileSystem remoteFS = FileSystem.get(conf);
 
-      // //////////// Set up JobJar to be localized properly on the remote NM.
+      configureJobJar(conf, localResources);
+
+      configureJobConf(conf, localResources, oldJobId);
+
+      // Setup DistributedCache
+      MRApps.setupDistributedCache(conf, localResources);
+
+      taskCredentialsBuffer =
+          configureTokens(jobToken, credentials, serviceData);
+
+      addExternalShuffleProviders(conf, serviceData);
+
+      environment = configureEnv(conf);
+
+    } catch (IOException e) {
+      throw new YarnRuntimeException(e);
+    }
+
+    // Construct the actual Container
+    // The null fields are per-container and will be constructed for each
+    // container separately.
+    ContainerLaunchContext container =
+        ContainerLaunchContext.newInstance(localResources, environment, null,
+            serviceData, taskCredentialsBuffer, applicationACLs);
+
+    return container;
+  }
+
+  private static Map<String, String> configureEnv(Configuration conf)
+      throws IOException {
+    Map<String, String> environment = new HashMap<String, String>();
+    MRApps.addToEnvironment(environment, Environment.CLASSPATH.name(),
+        getInitialClasspath(conf), conf);
+
+    if (initialAppClasspath != null) {
+      MRApps.addToEnvironment(environment, Environment.APP_CLASSPATH.name(),
+          initialAppClasspath, conf);
+    }
+
+    // Shell
+    environment.put(Environment.SHELL.name(), conf
+        .get(MRJobConfig.MAPRED_ADMIN_USER_SHELL, MRJobConfig.DEFAULT_SHELL));
+
+    // Add pwd to LD_LIBRARY_PATH, add this before adding anything else
+    MRApps.addToEnvironment(environment, Environment.LD_LIBRARY_PATH.name(),
+        MRApps.crossPlatformifyMREnv(conf, Environment.PWD), conf);
+
+    // Add the env variables passed by the admin
+    MRApps.setEnvFromInputString(environment,
+        conf.get(MRJobConfig.MAPRED_ADMIN_USER_ENV,
+            MRJobConfig.DEFAULT_MAPRED_ADMIN_USER_ENV),
+        conf);
+    return environment;
+  }
+
+  private static void configureJobJar(Configuration conf,
+      Map<String, LocalResource> localResources) throws IOException {
+    // Set up JobJar to be localized properly on the remote NM.
     String jobJar = conf.get(MRJobConfig.JAR);
     if (jobJar != null) {
       final Path jobJarPath = new Path(jobJar);
@@ -786,30 +842,31 @@ private static ContainerLaunchContext createCommonContainerLaunchContext(
       LOG.info("Job jar is not present. "
           + "Not adding any jar to the list of resources.");
     }
-      // //////////// End of JobJar setup
+  }
 
-      // //////////// Set up JobConf to be localized properly on the remote NM.
+  private static void configureJobConf(Configuration conf,
-      Path path =
+      Map<String, LocalResource> localResources,
-          MRApps.getStagingAreaDir(conf, UserGroupInformation
+      final org.apache.hadoop.mapred.JobID oldJobId) throws IOException {
-              .getCurrentUser().getShortUserName());
+    // Set up JobConf to be localized properly on the remote NM.
-      Path remoteJobSubmitDir =
+    Path path = MRApps.getStagingAreaDir(conf,
-          new Path(path, oldJobId.toString());
+        UserGroupInformation.getCurrentUser().getShortUserName());
+    Path remoteJobSubmitDir = new Path(path, oldJobId.toString());
     Path remoteJobConfPath =
         new Path(remoteJobSubmitDir, MRJobConfig.JOB_CONF_FILE);
-      localResources.put(
+    FileSystem remoteFS = FileSystem.get(conf);
-          MRJobConfig.JOB_CONF_FILE,
+    localResources.put(MRJobConfig.JOB_CONF_FILE,
-          createLocalResource(remoteFS, remoteJobConfPath,
+        createLocalResource(remoteFS, remoteJobConfPath, LocalResourceType.FILE,
-              LocalResourceType.FILE, LocalResourceVisibility.APPLICATION));
+            LocalResourceVisibility.APPLICATION));
     LOG.info("The job-conf file on the remote FS is "
         + remoteJobConfPath.toUri().toASCIIString());
-      // //////////// End of JobConf setup
+  }
-
-      // Setup DistributedCache
-      MRApps.setupDistributedCache(conf, localResources);
 
+  private static ByteBuffer configureTokens(Token<JobTokenIdentifier> jobToken,
+      Credentials credentials,
+      Map<String, ByteBuffer> serviceData) throws IOException {
     // Setup up task credentials buffer
-      LOG.info("Adding #" + credentials.numberOfTokens()
+    LOG.info("Adding #" + credentials.numberOfTokens() + " tokens and #"
-          + " tokens and #" + credentials.numberOfSecretKeys()
+        + credentials.numberOfSecretKeys()
         + " secret keys for NM use for launching container");
     Credentials taskCredentials = new Credentials(credentials);
 
@@ -818,10 +875,10 @@ private static ContainerLaunchContext createCommonContainerLaunchContext(
     TokenCache.setJobToken(jobToken, taskCredentials);
 
     DataOutputBuffer containerTokens_dob = new DataOutputBuffer();
-      LOG.info("Size of containertokens_dob is "
+    LOG.info(
-          + taskCredentials.numberOfTokens());
+        "Size of containertokens_dob is " + taskCredentials.numberOfTokens());
     taskCredentials.writeTokenStorageToStream(containerTokens_dob);
-      taskCredentialsBuffer =
+    ByteBuffer taskCredentialsBuffer =
         ByteBuffer.wrap(containerTokens_dob.getData(), 0,
             containerTokens_dob.getLength());
 
@@ -835,83 +892,47 @@ private static ContainerLaunchContext createCommonContainerLaunchContext(
           + " Using job token as shuffle secret.");
       shuffleSecret = jobToken.getPassword();
     }
-      Token<JobTokenIdentifier> shuffleToken = new Token<JobTokenIdentifier>(
+    Token<JobTokenIdentifier> shuffleToken =
-          jobToken.getIdentifier(), shuffleSecret, jobToken.getKind(),
+        new Token<JobTokenIdentifier>(jobToken.getIdentifier(), shuffleSecret,
-          jobToken.getService());
+            jobToken.getKind(), jobToken.getService());
     serviceData.put(ShuffleHandler.MAPREDUCE_SHUFFLE_SERVICEID,
         ShuffleHandler.serializeServiceData(shuffleToken));
+    return taskCredentialsBuffer;
+  }
 
+  private static void addExternalShuffleProviders(Configuration conf,
+      Map<String, ByteBuffer> serviceData) {
     // add external shuffle-providers - if any
     Collection<String> shuffleProviders = conf.getStringCollection(
         MRJobConfig.MAPREDUCE_JOB_SHUFFLE_PROVIDER_SERVICES);
-      if (! shuffleProviders.isEmpty()) {
+    if (!shuffleProviders.isEmpty()) {
-        Collection<String> auxNames = conf.getStringCollection(
+      Collection<String> auxNames =
-            YarnConfiguration.NM_AUX_SERVICES);
+          conf.getStringCollection(YarnConfiguration.NM_AUX_SERVICES);
 
       for (final String shuffleProvider : shuffleProviders) {
-          if (shuffleProvider.equals(ShuffleHandler.MAPREDUCE_SHUFFLE_SERVICEID)) {
+        if (shuffleProvider
-            continue; // skip built-in shuffle-provider that was already inserted with shuffle secret key
+            .equals(ShuffleHandler.MAPREDUCE_SHUFFLE_SERVICEID)) {
+          continue; // skip built-in shuffle-provider that was already inserted
+                    // with shuffle secret key
         }
         if (auxNames.contains(shuffleProvider)) {
-                LOG.info("Adding ShuffleProvider Service: " + shuffleProvider + " to serviceData");
+          LOG.info("Adding ShuffleProvider Service: " + shuffleProvider
+              + " to serviceData");
           // This only serves for INIT_APP notifications
-                // The shuffle service needs to be able to work with the host:port information provided by the AM
+          // The shuffle service needs to be able to work with the host:port
-                // (i.e. shuffle services which require custom location / other configuration are not supported)
+          // information provided by the AM
+          // (i.e. shuffle services which require custom location / other
+          // configuration are not supported)
           serviceData.put(shuffleProvider, ByteBuffer.allocate(0));
-          }
+        } else {
-          else {
+          throw new YarnRuntimeException("ShuffleProvider Service: "
-            throw new YarnRuntimeException("ShuffleProvider Service: " + shuffleProvider +
+              + shuffleProvider
-            " was NOT found in the list of aux-services that are available in this NM." +
+              + " was NOT found in the list of aux-services that are "
-            " You may need to specify this ShuffleProvider as an aux-service in your yarn-site.xml");
+              + "available in this NM. You may need to specify this "
+              + "ShuffleProvider as an aux-service in your yarn-site.xml");
         }
       }
     }
-
-      MRApps.addToEnvironment(
-          environment,  
-          Environment.CLASSPATH.name(), 
-          getInitialClasspath(conf), conf);
-
-      if (initialAppClasspath != null) {
-        MRApps.addToEnvironment(
-            environment,  
-            Environment.APP_CLASSPATH.name(), 
-            initialAppClasspath, conf);
-      }
-    } catch (IOException e) {
-      throw new YarnRuntimeException(e);
-    }
-
-    // Shell
-    environment.put(
-        Environment.SHELL.name(), 
-        conf.get(
-            MRJobConfig.MAPRED_ADMIN_USER_SHELL, 
-            MRJobConfig.DEFAULT_SHELL)
-            );
-
-    // Add pwd to LD_LIBRARY_PATH, add this before adding anything else
-    MRApps.addToEnvironment(
-        environment, 
-        Environment.LD_LIBRARY_PATH.name(), 
-        MRApps.crossPlatformifyMREnv(conf, Environment.PWD), conf);
-
-    // Add the env variables passed by the admin
-    MRApps.setEnvFromInputString(
-        environment, 
-        conf.get(
-            MRJobConfig.MAPRED_ADMIN_USER_ENV, 
-            MRJobConfig.DEFAULT_MAPRED_ADMIN_USER_ENV), conf
-        );
-
-    // Construct the actual Container
-    // The null fields are per-container and will be constructed for each
-    // container separately.
-    ContainerLaunchContext container =
-        ContainerLaunchContext.newInstance(localResources, environment, null,
-          serviceData, taskCredentialsBuffer, applicationACLs);
-
-    return container;
   }
 
   static ContainerLaunchContext createContainerLaunchContext(