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：

[root@SC-026 hadoop-1.0.3]# mkdir testFiles
[root@SC-026 hadoop-1.0.3]# cd testFiles/
[root@SC-026 testFiles]# echo "hello world, bye bye, world." > file1.txt
[root@SC-026 testFiles]# echo "hello hadoop, how are you? hadoop." > file2.txt

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。
遇到问题，报错信息如下：

[root@SC-026 hadoop-1.0.3]# 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.

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：

[root@SC-026 hadoop-1.0.3]# bin/hadoop dfsadmin -safemode leave
Safe mode is OFF
[root@SC-026 hadoop-1.0.3]# bin/hadoop dfs -put ./testFiles input

三、执行测试任务，输出到output：

[root@SC-026 hadoop-1.0.3]# 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

四、查看结果：

[root@SC-026 hadoop-1.0.3]# 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

将结果从HDFS复制到本地再查看：

[root@SC-026 hadoop-1.0.3]# bin/hadoop dfs -get output output
[root@SC-026 hadoop-1.0.3]# 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

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