MAPREDUCE-5484. YarnChild unnecessarily loads job conf twice (Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1518858 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -25,6 +25,8 @@ Release 2.3.0 - UNRELEASED
 
   OPTIMIZATIONS
 
+    MAPREDUCE-5484. YarnChild unnecessarily loads job conf twice (Sandy Ryza)
+
   BUG FIXES
 
     MAPREDUCE-5316. job -list-attempt-ids command does not handle illegal

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapred/YarnChild.java

@@ -75,9 +75,9 @@ class YarnChild {
     Thread.setDefaultUncaughtExceptionHandler(new YarnUncaughtExceptionHandler());
     LOG.debug("Child starting");
 
-    final JobConf defaultConf = new JobConf();
-    defaultConf.addResource(MRJobConfig.JOB_CONF_FILE);
-    UserGroupInformation.setConfiguration(defaultConf);
+    final JobConf job = new JobConf();
+    job.addResource(MRJobConfig.JOB_CONF_FILE);
+    UserGroupInformation.setConfiguration(job);
 
     String host = args[0];
     int port = Integer.parseInt(args[1]);
@@ -111,7 +111,7 @@ class YarnChild {
       @Override
       public TaskUmbilicalProtocol run() throws Exception {
         return (TaskUmbilicalProtocol)RPC.getProxy(TaskUmbilicalProtocol.class,
-            TaskUmbilicalProtocol.versionID, address, defaultConf);
+            TaskUmbilicalProtocol.versionID, address, job);
       }
     });
 
@@ -140,7 +140,7 @@ class YarnChild {
       YarnChild.taskid = task.getTaskID();
 
       // Create the job-conf and set credentials
-      final JobConf job = configureTask(task, credentials, jt);
+      configureTask(job, task, credentials, jt);
 
       // Initiate Java VM metrics
       JvmMetrics.initSingleton(jvmId.toString(), job.getSessionId());
@@ -254,11 +254,10 @@ class YarnChild {
     job.set(MRJobConfig.JOB_LOCAL_DIR,workDir.toString());
   }
 
-  private static JobConf configureTask(Task task, Credentials credentials,
-      Token<JobTokenIdentifier> jt) throws IOException {
-    final JobConf job = new JobConf(MRJobConfig.JOB_CONF_FILE);
+  private static void configureTask(JobConf job, Task task,
+      Credentials credentials, Token<JobTokenIdentifier> jt) throws IOException {
     job.setCredentials(credentials);
-
+    
     ApplicationAttemptId appAttemptId =
         ConverterUtils.toContainerId(
             System.getenv(Environment.CONTAINER_ID.name()))
@@ -300,7 +299,6 @@ class YarnChild {
     writeLocalJobFile(localTaskFile, job);
     task.setJobFile(localTaskFile.toString());
     task.setConf(job);
-    return job;
   }
 
   /**