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

程裕强

发布于 2022-05-06 18:31:30

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发布于 2022-05-06 18:31:30

文章被收录于专栏：大数据学习笔记

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 output
17/05/12 09:04:39 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:8032
17/05/12 09:04:41 INFO input.FileInputFormat: Total input paths to process : 1
17/05/12 09:04:41 INFO mapreduce.JobSubmitter: number of splits:1
17/05/12 09:04:42 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1494590593576_0001
17/05/12 09:04:43 INFO impl.YarnClientImpl: Submitted application application_1494590593576_0001
17/05/12 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_0001
17/05/12 09:05:08 INFO mapreduce.Job: Job job_1494590593576_0001 running in uber mode : false
17/05/12 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 successfully
17/05/12 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-00000
Hadoop  3
Hello   2
Java    2
World   2
[root@node1 hadoop-2.7.3]#