我在vmware的ubuntu 12.04单节点环境中运行hadoop wordcount示例。我像这样运行这个例子:——
hadoop@master:~/hadoop$ hadoop jar hadoop-examples-1.0.4.jar wordcount
/home/hadoop/gutenberg/ /home/hadoop/gutenberg-output
我在下面的位置有一个输入文件:
/home/hadoop/gutenberg
和输出文件的位置是:
/home/hadoop/gutenberg-output
当我运行单词计数程序时，我得到以下错误:——
13/04/18 06:02:10 INFO mapred.JobClient: Cleaning up the staging area
hdfs://localhost:54310/home/hadoop/tmp/mapred/staging/hadoop/.staging/job_201304180554_0001
13/04/18 06:02:10 ERROR security.UserGroupInformation: PriviledgedActionException
as:hadoop cause:org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory
/home/hadoop/gutenberg-output already exists
org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory
/home/hadoop/gutenberg-output already exists at
org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.j
ava:137) at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:887) at
org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:850) at
java.security.AccessController.doPrivileged(Native Method) at
javax.security.auth.Subject.doAs(Subject.java:416) at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121) at
org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:850) at
org.apache.hadoop.mapreduce.Job.submit(Job.java:500) at
org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:530) at
org.apache.hadoop.examples.WordCount.main(WordCount.java:67) at
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616) at
org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139) at
org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:64) 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:616) at
org.apache.hadoop.util.RunJar.main(RunJar.java:156) hadoop@master:~/hadoop$ bin/stop-
all.sh Warning: $HADOOP_HOME is deprecated. stopping jobtracker localhost: stopping
tasktracker stopping namenode localhost: stopping datanode localhost: stopping
secondarynamenode hadoop@master:~/hadoop$
删除已经存在的输出文件，或者输出到其他文件
(我有点好奇您认为错误消息的其他解释是什么。)
就像Dave(和例外情况)所说的那样，您的输出目录已经存在。您要么需要输出到不同的目录，要么首先删除现有的目录，使用:
hadoop fs -rmr /home/hadoop/gutenberg-output
如果您已经创建了自己的.jar并试图运行它，请注意:
为了运行你的作业，你必须写这样的东西:
hadoop jar <jar-path> <package-path> <input-in-hdfs-path> <output-in-hdfs-path>
但是如果你仔细看看你的驱动程序代码，你会发现你已经设置了arg[0]作为输入，arg[1]作为输出…我将显示它:
FileInputFormart.addInputPath(conf, new Path(args[0]));
FileOutFormart.setOutputPath(conf, new Path(args[1]));
但是，hadoop将arg[0]作为<package-path>而不是<input-in-hdfs-path>，将arg[1]作为<input-in-hdfs-path>而不是<output-in-hdfs-path>
所以，为了使它工作，你应该使用:
FileInputFormart.addInputPath(conf, new Path(args[1]));
FileOutFormart.setOutputPath(conf, new Path(args[2]));
用arg[1]和arg[2]，所以它会得到正确的东西!：）希望对你有所帮助。欢呼。
检查是否存在" tmp "文件夹
hadoop fs -ls/如果您看到输出文件夹或'tmp'，请删除它们(考虑没有正在运行的活动作业)
hadoop fs -rmr/tmp