安装完Hadoop2版本后，启动测试程序报如下异常：

/04/14 15:29:16 INFO mapreduce.Job: Job job_1398669840354_0003 failed with state FAILED due to: Application application_1398669840354_0003 failed 2 times due to AM Container for appattempt_1398669840354_0003_000002 exited with  exitCode: 1 due to: Exception from container-launch: org.apache.hadoop.util.Shell$ExitCodeException:org.apache.hadoop.util.Shell$ExitCodeException:
	at org.apache.hadoop.util.Shell.runCommand(Shell.java:505)
	at org.apache.hadoop.util.Shell.run(Shell.java:418)
	at org.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:650)
	at org.apache.hadoop.yarn.server.nodemanager.DefaultContainerExecutor.launchContainer(DefaultContainerExecutor.java:195)
	at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:283)
	at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:79)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)Container exited with a non-zero exit code 1.Failing this attempt.. Failing the application./04/28 15:29:16 INFO mapreduce.Job: Counters: 0Job Finished in 5.2 seconds
java.io.FileNotFoundException: File does not exist: hdfs://192.168.1.23:8020/user/hadoop/QuasiMonteCarlo_1398670150085_932896136/out/reduce-out
	at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1128)
	at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1120)
	at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
	at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1120)
	at org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1749)
	at org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1773)
	at org.apache.hadoop.examples.QuasiMonteCarlo.estimatePi(QuasiMonteCarlo.java:314)
	at org.apache.hadoop.examples.QuasiMonteCarlo.run(QuasiMonteCarlo.java:354)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
	at org.apache.hadoop.examples.QuasiMonteCarlo.main(QuasiMonteCarlo.java:363)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:72)
	at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144)
	at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:74)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.hadoop.util.RunJar.main(RunJar.java:212)

修改 mapred-site.xml，添加如下配置

mapreduce.application.classpath 
$HADOOP_CONF_DIR,$HADOOP_COMMON_HOME/*, 
$HADOOP_COMMON_HOME/lib/*, 
$HADOOP_HDFS_HOME/*, 
$HADOOP_HDFS_HOME/lib/*, 
$HADOOP_MAPRED_HOME/*, 
$HADOOP_MAPRED_HOME/lib/*, 
$HADOOP_YARN_HOME/*, 
$HADOOP_YARN_HOME/lib/*