终于成功运行第一个Hadoop程序
之前一直只在Windows上玩 为了Hadoop 只好迁移到Ubuntu上～记录一下自己的历程：
1. 在Windows上安装Ubuntu
方法就是通过wubi安装，全自动化，非常傻瓜，太适合我这种linux小白了！
wubi可以直接在官网下载，当时我不知道，使用的还是从iso之中解压出来的程序 哈哈
下载地址：http://www.ubuntu.com/download/desktop/windows-installer
自己选择合适的来用啊
2. 进行各种配置，包括： JDK Hadoop, 当然也包括安装一个拼音输入法。。。。
JDK以及配置Hadoop的方法，完全参考的：http://os.iyunv.com/art/201211/364167.htm
Note: 跟着上面的步骤走下来我才知道，这个实际上是伪分布式～
3. 开始跑一个例子程序吧～
hadoop自带的例子程序 就在解压出来的hadoop文件夹之中，但是一开始一直遇到一个很奇怪的问题：报错如下：
13/07/06 20:10:59 ERROR security.UserGroupInformation: PriviledgedActionException as:hadoop cause:org.apache.hadoop.mapreduce.lib.input.InvalidInputException: Input path does not exist: hdfs://localhost:9000/usr/local/hadoop/input
org.apache.hadoop.mapreduce.lib.input.InvalidInputException: Input path does not exist: hdfs://localhost:9000/usr/local/hadoop/input
at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.listStatus(FileInputFormat.java:235)
at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.getSplits(FileInputFormat.java:252)
at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:1054)
at org.apache.hadoop.mapred.JobClient.writeSplits(JobClient.java:1071)
at org.apache.hadoop.mapred.JobClient.access$700(JobClient.java:179)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:983)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:936)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1190)
at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:936)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:550)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:580)
at org.apache.hadoop.examples.WordCount.main(WordCount.java:82)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java: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:606)
at org.apache.hadoop.util.RunJar.main(RunJar.java:160)
在各种google之后才知道，hdfs里面还没有把input这个文件夹加上去
敲入命令：
hadoop@ubuntu:/usr/local/hadoop$ bin/hadoop dfs -put input input
这样之后，通过dfs的-ls命令终于能找到input文件夹：
hadoop@ubuntu:/usr/local/hadoop$ bin/hadoop dfs -ls
Found 1 items
drwxr-xr-x - hadoop supergroup 0 2013-07-06 20:12 /user/hadoop/input
这个时候再次执行运行例子程序的命令，就没有之前遇到的异常：
Input path does not exist: hdfs://localhost:9000/usr/local/hadoop/input
最后正确执行的log如下：
hadoop@ubuntu:/usr/local/hadoop$ bin/hadoop jar hadoop-examples-1.2.0.jar wordcount input wc_output2
13/07/06 20:12:39 INFO input.FileInputFormat: Total input paths to process : 1
13/07/06 20:12:39 INFO util.NativeCodeLoader: Loaded the native-hadoop library
13/07/06 20:12:39 WARN snappy.LoadSnappy: Snappy native library not loaded
13/07/06 20:12:40 INFO mapred.JobClient: Running job: job_201307061937_0006
13/07/06 20:12:41 INFO mapred.JobClient: map 0% reduce 0%
13/07/06 20:12:46 INFO mapred.JobClient: map 100% reduce 0%
13/07/06 20:12:53 INFO mapred.JobClient: map 100% reduce 33%
13/07/06 20:12:55 INFO mapred.JobClient: map 100% reduce 100%
13/07/06 20:12:55 INFO mapred.JobClient: Job complete: job_201307061937_0006
13/07/06 20:12:56 INFO mapred.JobClient: Counters: 29
13/07/06 20:12:56 INFO mapred.JobClient: Job Counters
13/07/06 20:12:56 INFO mapred.JobClient: Launched reduce tasks=1
13/07/06 20:12:56 INFO mapred.JobClient: SLOTS_MILLIS_MAPS=4785
13/07/06 20:12:56 INFO mapred.JobClient: Total time spent by all reduces waiting after reserving slots (ms)=0
13/07/06 20:12:56 INFO mapred.JobClient: Total time spent by all maps waiting after reserving slots (ms)=0
13/07/06 20:12:56 INFO mapred.JobClient: Launched map tasks=1
13/07/06 20:12:56 INFO mapred.JobClient: Data-local map tasks=1
13/07/06 20:12:56 INFO mapred.JobClient: SLOTS_MILLIS_REDUCES=8917
13/07/06 20:12:56 INFO mapred.JobClient: File Output Format Counters
13/07/06 20:12:56 INFO mapred.JobClient: Bytes Written=24591
13/07/06 20:12:56 INFO mapred.JobClient: FileSystemCounters
13/07/06 20:12:56 INFO mapred.JobClient: FILE_BYTES_READ=34471
13/07/06 20:12:56 INFO mapred.JobClient: HDFS_BYTES_READ=46619
13/07/06 20:12:56 INFO mapred.JobClient: FILE_BYTES_WRITTEN=180119
13/07/06 20:12:56 INFO mapred.JobClient: HDFS_BYTES_WRITTEN=24591
13/07/06 20:12:56 INFO mapred.JobClient: File Input Format Counters
13/07/06 20:12:56 INFO mapred.JobClient: Bytes Read=46510
13/07/06 20:12:56 INFO mapred.JobClient: Map-Reduce Framework
13/07/06 20:12:56 INFO mapred.JobClient: Map output materialized bytes=34471
13/07/06 20:12:56 INFO mapred.JobClient: Map input records=561
13/07/06 20:12:56 INFO mapred.JobClient: Reduce shuffle bytes=34471
13/07/06 20:12:56 INFO mapred.JobClient: Spilled Records=4992
13/07/06 20:12:56 INFO mapred.JobClient: Map output bytes=77170
13/07/06 20:12:56 INFO mapred.JobClient: Total committed heap usage (bytes)=219152384
13/07/06 20:12:56 INFO mapred.JobClient: CPU time spent (ms)=2450
13/07/06 20:12:56 INFO mapred.JobClient: Combine input records=7804
13/07/06 20:12:56 INFO mapred.JobClient: SPLIT_RAW_BYTES=109
13/07/06 20:12:56 INFO mapred.JobClient: Reduce input records=2496
13/07/06 20:12:56 INFO mapred.JobClient: Reduce input groups=2496
13/07/06 20:12:56 INFO mapred.JobClient: Combine output records=2496
13/07/06 20:12:56 INFO mapred.JobClient: Physical memory (bytes) snapshot=280190976
13/07/06 20:12:56 INFO mapred.JobClient: Reduce output records=2496
13/07/06 20:12:56 INFO mapred.JobClient: Virtual memory (bytes) snapshot=2009939968
13/07/06 20:12:56 INFO mapred.JobClient: Map output records=7804
最后，查看运行完成之后的结果：
bin/hadoop dfs -cat wc_output2/* | more
备注：
几个GUI管理网址：［目前我知道的］
http://localhost:50070/dfshealth.jsp
http://localhost:50030/jobtracker.jsp
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