在eclipse中调试Hadoop遇到的问题

14/09/10 15:42:55 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable

14/09/10 15:42:55 ERROR security.UserGroupInformation: PriviledgedActionException as:hadoop cause:java.io.IOException: Failed to set permissions of path: \tmp\hadoop-hadoop\mapred\staging\hadoop-1275750701\.staging to 0700

Exception in thread "main" java.io.IOException: Failed to set permissions of path: \tmp\hadoop-hadoop\mapred\staging\hadoop-1275750701\.staging to 0700

at org.apache.hadoop.fs.FileUtil.checkReturnValue(FileUtil.java:689)

at org.apache.hadoop.fs.FileUtil.setPermission(FileUtil.java:662)

at org.apache.hadoop.fs.RawLocalFileSystem.setPermission(RawLocalFileSystem.java:509)

at org.apache.hadoop.fs.RawLocalFileSystem.mkdirs(RawLocalFileSystem.java:344)

at org.apache.hadoop.fs.FilterFileSystem.mkdirs(FilterFileSystem.java:189)

at org.apache.hadoop.mapreduce.JobSubmissionFiles.getStagingDir(JobSubmissionFiles.java:116)

at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:918)

at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:912)

at java.security.AccessController.doPrivileged(Native Method)

at javax.security.auth.Subject.doAs(Subject.java:415)

at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1149)

at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:912)

at org.apache.hadoop.mapreduce.Job.submit(Job.java:500)

at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:530)

at hadoop.run.HadoopMain.run(HadoopMain.java:43)

at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)

at hadoop.run.HadoopMain.main(HadoopMain.java:89)

解决方案：

程序打成jar包可以在Hadoop中运行，但是在eclipse中出现上述问题。此问题是window下的权限问题，因为在window下是虚拟的Hadoop运行环境，所以解决方式也比较粗暴。

将window下的/hadoop-1.0.2/src/core/org/apache/hadoop/fs/FileUtil.java里面的checkReturnValue方法体注释掉如下：

private static void checkReturnValue(boolean rv, File p,                                        FsPermission permission                                       ) throws IOException {    /**	if (!rv) {      throw new IOException("Failed to set permissions of path: " + p +                             " to " +                             String.format("%04o", permission.toShort()));    }	**/  }

重新编译打包hadoop-core-1.0.2.jar，替换掉hadoop-1.0.2根目录下的hadoop-core-1.0.2.jar即可

不会编译hadoop-core-1.0.2.jar的可以采用另一种方式，仅编译/hadoop-1.0.2/src/core/org/apache/hadoop/fs/FileUtil.java即可；步骤如下：
使用eclipse工具，新建一个MapReduce项目；然后将/hadoop-1.0.2/src/core下面的org文件夹以及org下所以子目录复制到MapReduce项目的src下找到[code]/hadoop-1.0.2/src/core/org/apache/hadoop/fs/FileUtil.java按照上述修改更改保存后，到workspace下面找到该项目编译后的.class文件（FileUtil$CygPathCommand.class和
FileUtil.class），然后找到hadoop-core-1.0.2.jar，双击打开，将这个文件替换即可。