在前一篇文章中，介绍了一写常见问题的解决方法。
但是，当我重装系统，再次按照前面一篇文章( http://winseclone.iteye.com/blog/1734737 ) 安装cygwin和hadoop-1时，发现伪分布式环境使用mapred时，总是报错。（忘了，但是好像当时没有遇到过这种情况。就当是安装win8送给自己的礼物吧！）。
怀疑了很多东西，配置有问题，重新自定hadoop.tmp.dir，把hadoop-1.1.0换成hadoop-1.0.0等等。
错误日志如下：
$ hhadoop fs -rmr /test/output ; hhadoop jar hadoop-examples-1.0.0.jar wordcount /test/input /test/output
Deleted hdfs://WINSE:9000/test/output
13/03/23 22:46:07 INFO input.FileInputFormat: Total input paths to process : 1
13/03/23 22:46:08 INFO mapred.JobClient: Running job: job_201303232144_0002
13/03/23 22:46:09 INFO mapred.JobClient: map 0% reduce 0%
13/03/23 22:46:16 INFO mapred.JobClient: Task Id : attempt_201303232144_0002_m_000002_0, Status : FAILED
java.lang.Throwable: Child Error
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:272)
Caused by: java.io.IOException: Task process exit with nonzero status of -1.
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:259)
13/03/23 22:46:16 WARN mapred.JobClient: Error reading task outputhttp://WINSE:50060/tasklog?plaintext=true&attemptid=attempt_201303232144_0002_m_000002_0&filter=stdout
13/03/23 22:46:16 WARN mapred.JobClient: Error reading task outputhttp://WINSE:50060/tasklog?plaintext=true&attemptid=attempt_201303232144_0002_m_000002_0&filter=stderr
13/03/23 22:46:22 INFO mapred.JobClient: Task Id : attempt_201303232144_0002_m_000002_1, Status : FAILED
经过修改原来，不断的修改，加入sysout打印，算是最终找出程序出现错误的地方！
org.apache.hadoop.mapred.DefaultTaskController.java #launchTask
org.apache.hadoop.mapred.JvmManager.java #runChild
org.apache.hadoop.mapred.TaskRunner.java #launchJvmAndWait
org.apache.hadoop.fs.FileUtil.java #checkReturnValue
org.apache.hadoop.fs.RawLocalFileSystem.java #setPermission #mkdirs
发现在org.apache.hadoop.fs.RawLocalFileSystem.mkdirs(Path)方法中，建立文件的路径方法检查attempt_201303232144_0002_m_000001_0是否为文件夹会失败！
而在cygwin中查看：
Winseliu@WINSE ~/hadoop/logs/userlogs/job_201303232144_0002 $ ll 总用量 9 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000001_0 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000001_0 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000001_1 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000001_1 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000001_2 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000001_2 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000001_3 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000001_3 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000002_0 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000002_0 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000002_1 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000002_1 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000002_2 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000002_2 lrwxrwxrwx 1 Winseliu None 89 3月 23 22:46 attempt_201303232144_0002_m_000002_3 -> /cluster/mapred/local/userlogs/job_201303232144_0002/attempt_201303232144_0002_m_000002_3 -rwxr-xr-x 1 Winseliu None 404 3月 23 22:46 job-acls.xml
对于linux来说，这些就是引用到另一个文件夹，它本身应该也是文件夹！但是window的jdk不认识这些东西！
public boolean mkdirs(Path f) throws IOException {
Path parent = f.getParent();
File p2f = pathToFile(f);
return (parent == null || mkdirs(parent)) &&
(p2f.mkdir() || p2f.isDirectory());
}
所以在判断p2f.isDirectory()返回false，然后会抛出IOException，最终以-1的状态退出Map Child的程序！
使用org.apache.hadoop.mapred.TaskRunner.prepareLogFiles(TaskAttemptID, boolean)方法来制定了输出的日志输出的位置。在最终执行的会在shell命令中把输出的sysout和syserr输出到日志文件中。userlogs的父目录是使用hadoop.log.dir系统属性来配置的！
mapred.DefaultTaskController.launchTask()
|--mapred.TaskLog.buildCommandLine()
临时解决方法：
把hadoop.log.dir定位到真正mapred日志的目录( mapred.local.dir : ${hadoop.tmp.dir}/mapred/local )！
export HADOOP_LOG_DIR=/cluster/mapred/local
把windows的/cluster映射到cygwin(linux)的/cluster:
Winseliu@WINSE ~/hadoop $ ll /cygdrive/c | grep cluster drwxr-xr-x+ 1 Winseliu None 0 3月 24 00:08 cluster Winseliu@WINSE ~/hadoop $ ll / | grep cluster lrwxrwxrwx 1 Winseliu None 19 3月 23 09:39 cluster -> /cygdrive/c/cluster
但是，运行wordcount的例子时，还是不正常！查看tasktracker的日志时，发现有String装成Integer的NumberFormatException异常!
修改org.apache.hadoop.mapred.JvmManager.JvmManagerForType.JvmRunner.kill()方法。添加pidStr为空字符串的检查！
String pidStr = jvmIdToPid.get(jvmId);
if (pidStr != null && !pidStr.isEmpty()) {
然后，终于看到Finish咯！在/test/output/part-r-00000中也看到了结果。
其他一些简化处理，即配置文件：
alias startCluster="~/hadoop/bin/start-all.sh" alias stopCluster="~/hadoop/bin/stop-all.sh; ~/hadoop/bin/stop-all.sh" alias hhadoop="~/hadoop/bin/hadoop"
Winseliu@WINSE ~ $ ll | grep hadoop lrwxrwxrwx 1 Winseliu None 12 3月 23 10:44 hadoop -> hadoop-1.0.0 drwx------+ 1 Winseliu None 0 3月 24 00:06 hadoop-1.0.0
<!-- core-site.xml --> <configuration> <property> <name>fs.default.name</name> <value>hdfs://WINSE:9000</value> </property> <property> <name>hadoop.tmp.dir</name> <value>/cluster</value> </property> </configuration> <!-- hdfs-site.xml --> <configuration> <property> <name>dfs.replication</name> <value>1</value> </property> <property> <name>dfs.permissions</name> <value>false</value> </property> <property> <name>dfs.permissions.supergroup</name> <value>None</value> </property> <property> <name>dfs.safemode.extension</name> <value>1000</value> </property> </configuration> <!-- mapred-site.xml --> <configuration> <property> <name>mapred.job.tracker</name> <value>WINSE:9001</value> </property> </configuration>
关于查看启动的进程，看可以通过任务管理器来查看：
