hadoop测试worldcount

hadoop测试worldcount，统计每个单词出现的个数

一、首先创建新目录testFiles，并在目录下创建两个测试数据文本文件如下：
[code="shell"]# mkdir testFiles
# cd testFiles/
# echo "hello world, bye bye, world." > file1.txt
# echo "hello hadoop, how are you? hadoop." > file2.txt[/code]

二、将本地文件系统上的./testFiles目录拷贝到HDFS的根目录下，目录名为input。
[color=darkred]遇到问题，报错信息如下：[/color]
[code="shell"]# bin/hadoop dfs -put ./testFiles input
put: org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot create directory /user/root/input. Name node is in safe mode.[/code]
问题说明hadoop的namenode处在安全模式下，通过以下方式就可以离开安全模式，再次执行拷贝就成功了：
[code="shell"]# bin/hadoop dfsadmin -safemode leave
Safe mode is OFF
# bin/hadoop dfs -put ./testFiles input[/code]

三、执行测试任务，输出到output：
[code="shell"]# bin/hadoop jar hadoop-examples-1.0.3.jar wordcount input output
12/08/31 09:21:34 INFO input.FileInputFormat: Total input paths to process : 2
12/08/31 09:21:34 INFO util.NativeCodeLoader: Loaded the native-hadoop library
12/08/31 09:21:34 WARN snappy.LoadSnappy: Snappy native library not loaded
12/08/31 09:21:35 INFO mapred.JobClient: Running job: job_201208310909_0001
12/08/31 09:21:36 INFO mapred.JobClient: map 0% reduce 0%
12/08/31 09:21:57 INFO mapred.JobClient: map 50% reduce 0%
12/08/31 09:22:00 INFO mapred.JobClient: map 100% reduce 0%
12/08/31 09:22:12 INFO mapred.JobClient: map 100% reduce 100%
12/08/31 09:22:16 INFO mapred.JobClient: Job complete: job_201208310909_0001
12/08/31 09:22:16 INFO mapred.JobClient: Counters: 29
12/08/31 09:22:16 INFO mapred.JobClient: Job Counters
12/08/31 09:22:16 INFO mapred.JobClient: Launched reduce tasks=1
12/08/31 09:22:16 INFO mapred.JobClient: SLOTS_MILLIS_MAPS=27675
12/08/31 09:22:16 INFO mapred.JobClient: Total time spent by all reduces waiting after reserving slots (ms)=0
12/08/31 09:22:16 INFO mapred.JobClient: Total time spent by all maps waiting after reserving slots (ms)=0
12/08/31 09:22:16 INFO mapred.JobClient: Launched map tasks=2
12/08/31 09:22:16 INFO mapred.JobClient: Data-local map tasks=2
12/08/31 09:22:16 INFO mapred.JobClient: SLOTS_MILLIS_REDUCES=14460
12/08/31 09:22:16 INFO mapred.JobClient: File Output Format Counters
12/08/31 09:22:16 INFO mapred.JobClient: Bytes Written=78
12/08/31 09:22:16 INFO mapred.JobClient: FileSystemCounters
12/08/31 09:22:16 INFO mapred.JobClient: FILE_BYTES_READ=136
12/08/31 09:22:16 INFO mapred.JobClient: HDFS_BYTES_READ=278
12/08/31 09:22:16 INFO mapred.JobClient: FILE_BYTES_WRITTEN=64909
12/08/31 09:22:16 INFO mapred.JobClient: HDFS_BYTES_WRITTEN=78
12/08/31 09:22:16 INFO mapred.JobClient: File Input Format Counters
12/08/31 09:22:16 INFO mapred.JobClient: Bytes Read=64
12/08/31 09:22:16 INFO mapred.JobClient: Map-Reduce Framework
12/08/31 09:22:16 INFO mapred.JobClient: Map output materialized bytes=142
12/08/31 09:22:16 INFO mapred.JobClient: Map input records=2
12/08/31 09:22:16 INFO mapred.JobClient: Reduce shuffle bytes=142
12/08/31 09:22:16 INFO mapred.JobClient: Spilled Records=22
12/08/31 09:22:16 INFO mapred.JobClient: Map output bytes=108
12/08/31 09:22:16 INFO mapred.JobClient: CPU time spent (ms)=3480
12/08/31 09:22:16 INFO mapred.JobClient: Total committed heap usage (bytes)=411828224
12/08/31 09:22:16 INFO mapred.JobClient: Combine input records=11
12/08/31 09:22:16 INFO mapred.JobClient: SPLIT_RAW_BYTES=214
12/08/31 09:22:16 INFO mapred.JobClient: Reduce input records=11
12/08/31 09:22:16 INFO mapred.JobClient: Reduce input groups=10
12/08/31 09:22:16 INFO mapred.JobClient: Combine output records=11
12/08/31 09:22:16 INFO mapred.JobClient: Physical memory (bytes) snapshot=447000576
12/08/31 09:22:16 INFO mapred.JobClient: Reduce output records=10
12/08/31 09:22:16 INFO mapred.JobClient: Virtual memory (bytes) snapshot=1634324480
12/08/31 09:22:16 INFO mapred.JobClient: Map output records=11[/code]

四、查看结果：
[code="shell"]# bin/hadoop dfs -cat output/*
are 1
bye 1
bye, 1
hadoop, 1
hadoop. 1
hello 2
how 1
world, 1
world. 1
you? 1
cat: File does not exist: /user/root/output/_logs[/code]

将结果从HDFS复制到本地再查看：
[code="shell"]# bin/hadoop dfs -get output output
# cat output/*
cat: output/_logs: 是一个目录
are 1
bye 1
bye, 1
hadoop, 1
hadoop. 1
hello 2
how 1
world, 1
world. 1
you? 1[/code]


备注：bin/hadoop dfs –help 可以了解各种 HDFS命令的使用。