Hadoop基础教程-第2章 Hadoop快速入门（2.5 WordContent简单应用）

第2章 Hadoop快速入门

2.5 WordContent简单应用

Hadoop的HelloWorld程序

2.5.1 创建HDFS目录

hdfs命令位于bin目录下，通过hdfs dfs -mkdir命令可以创建一个目录。

[root@node1 hadoop-2.7.3]# bin/hdfs dfs -mkdir -p input

hdfs创建的目录默认会放到/user/{username}/目录下面，其中{username}是当前用户名。所以input目录应该在/user/root/下面。
下面通过｀hdfs dfs -ls｀命令可以查看HDFS目录文件

[root@node1 hadoop-2.7.3]# bin/hdfs dfs -ls /

2.5.2 上传文件到HDFS

在本地新建一个文本文件
vi /root/words.txt

[root@node1 hadoop-2.7.3]# vi /root/words.txt

随便输入几个单词，保存退出。

将本地文件/root/words.txt上传到HDFS
bin/hdfs dfs -put /root/words.txt input
bin/hdfs dfs -ls input

2.5.3 运行WordContent

执行下面命令：
bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar wordcount input output

[root@node1 hadoop-2.7.3]# bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar wordcount input output17/05/12 09:04:39 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:803217/05/12 09:04:41 INFO input.FileInputFormat: Total input paths to process : 117/05/12 09:04:41 INFO mapreduce.JobSubmitter: number of splits:117/05/12 09:04:42 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1494590593576_000117/05/12 09:04:43 INFO impl.YarnClientImpl: Submitted application application_1494590593576_000117/05/12 09:04:43 INFO mapreduce.Job: The url to track the job: http://node1:8088/proxy/application_1494590593576_0001/17/05/12 09:04:43 INFO mapreduce.Job: Running job: job_1494590593576_000117/05/12 09:05:08 INFO mapreduce.Job: Job job_1494590593576_0001 running in uber mode : false17/05/12 09:05:08 INFO mapreduce.Job:  map 0% reduce 0%17/05/12 09:05:19 INFO mapreduce.Job:  map 100% reduce 0%17/05/12 09:05:31 INFO mapreduce.Job:  map 100% reduce 100%17/05/12 09:05:32 INFO mapreduce.Job: Job job_1494590593576_0001 completed successfully17/05/12 09:05:32 INFO mapreduce.Job: Counters: 49    File System Counters        FILE: Number of bytes read=54        FILE: Number of bytes written=237325        FILE: Number of read operations=0        FILE: Number of large read operations=0        FILE: Number of write operations=0        HDFS: Number of bytes read=163        HDFS: Number of bytes written=32        HDFS: Number of read operations=6        HDFS: Number of large read operations=0        HDFS: Number of write operations=2    Job Counters         Launched map tasks=1        Launched reduce tasks=1        Data-local map tasks=1        Total time spent by all maps in occupied slots (ms)=8861        Total time spent by all reduces in occupied slots (ms)=8430        Total time spent by all map tasks (ms)=8861        Total time spent by all reduce tasks (ms)=8430        Total vcore-milliseconds taken by all map tasks=8861        Total vcore-milliseconds taken by all reduce tasks=8430        Total megabyte-milliseconds taken by all map tasks=9073664        Total megabyte-milliseconds taken by all reduce tasks=8632320    Map-Reduce Framework        Map input records=3        Map output records=9        Map output bytes=91        Map output materialized bytes=54        Input split bytes=108        Combine input records=9        Combine output records=4        Reduce input groups=4        Reduce shuffle bytes=54        Reduce input records=4        Reduce output records=4        Spilled Records=8        Shuffled Maps =1        Failed Shuffles=0        Merged Map outputs=1        GC time elapsed (ms)=249        CPU time spent (ms)=2950        Physical memory (bytes) snapshot=303017984        Virtual memory (bytes) snapshot=4157116416        Total committed heap usage (bytes)=165810176    Shuffle Errors        BAD_ID=0        CONNECTION=0        IO_ERROR=0        WRONG_LENGTH=0        WRONG_MAP=0        WRONG_REDUCE=0    File Input Format Counters         Bytes Read=55    File Output Format Counters         Bytes Written=32

2.5.4 查看结果

bin/hdfs dfs -ls output
bin/hdfs dfs -cat output/part-r-00000

[root@node1 hadoop-2.7.3]# bin/hdfs dfs -ls output/Found 2 items-rw-r--r--   1 root supergroup          0 2017-05-12 09:05 output/_SUCCESS-rw-r--r--   1 root supergroup         32 2017-05-12 09:05 output/part-r-00000[root@node1 hadoop-2.7.3]# bin/hdfs dfs -cat output/part-r-00000Hadoop  3Hello   2Java    2World   2[root@node1 hadoop-2.7.3]#