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大数据之(3)Hadoop环境MapReduce程序验证及hdfs常用命令

程序员文章站 2022-04-30 17:23:30
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一、MapReduce验证

  1. 本地创建一个test.txt文件
    vim test.txt
    输入一些英文句子如下:
Beijing is the capital of China
I love Beijing
I love China
  1. 上传test.txt到hdfs系统的 ouput目录
  • hdfs dfs -mkdir /user
  • hdfs dfs -mkdir /user/input
  • hdfs dfs -put test.txt /user/input
  1. 执行MapReduce例子程序
  • /hadoop/hadoop-2.9.0/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.9.0.jar替换成自己的对应目录。
hadoop jar /hadoop/hadoop-2.9.0/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.9.0.jar wordcount /user/input/test.txt output
  • 执行命令正常输出如下结果,map先从0-100然后reduce从0-100.
18/11/08 16:18:48 INFO client.RMProxy: Connecting to ResourceManager at master.hadoop/172.16.16.15:8032
18/11/08 16:18:49 INFO input.FileInputFormat: Total input files to process : 1
18/11/08 16:18:49 INFO mapreduce.JobSubmitter: number of splits:1
18/11/08 16:18:49 INFO Configuration.deprecation: yarn.resourcemanager.system-metrics-publisher.enabled is deprecated. Instead, use yarn.system-metrics-publisher.enabled
18/11/08 16:18:49 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1541665050140_0001
18/11/08 16:18:49 INFO impl.YarnClientImpl: Submitted application application_1541665050140_0001
18/11/08 16:18:49 INFO mapreduce.Job: The url to track the job: http://master.hadoop:8088/proxy/application_1541665050140_0001/
18/11/08 16:18:49 INFO mapreduce.Job: Running job: job_1541665050140_0001
18/11/08 16:18:55 INFO mapreduce.Job: Job job_1541665050140_0001 running in uber mode : false
18/11/08 16:18:55 INFO mapreduce.Job:  map 0% reduce 0%
18/11/08 16:19:00 INFO mapreduce.Job:  map 100% reduce 0%
18/11/08 16:19:05 INFO mapreduce.Job:  map 100% reduce 100%
18/11/08 16:19:06 INFO mapreduce.Job: Job job_1541665050140_0001 completed successfully
18/11/08 16:19:06 INFO mapreduce.Job: Counters: 49
	File System Counters
		FILE: Number of bytes read=106
		FILE: Number of bytes written=404235
		FILE: Number of read operations=0
		FILE: Number of large read operations=0
		FILE: Number of write operations=0
		HDFS: Number of bytes read=175
		HDFS: Number of bytes written=64
		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
		Rack-local map tasks=1
		Total time spent by all maps in occupied slots (ms)=1945
		Total time spent by all reduces in occupied slots (ms)=1574
		Total time spent by all map tasks (ms)=1945
		Total time spent by all reduce tasks (ms)=1574
		Total vcore-milliseconds taken by all map tasks=1945
		Total vcore-milliseconds taken by all reduce tasks=1574
		Total megabyte-milliseconds taken by all map tasks=1991680
		Total megabyte-milliseconds taken by all reduce tasks=1611776
	Map-Reduce Framework
		Map input records=3
		Map output records=12
		Map output bytes=107
		Map output materialized bytes=106
		Input split bytes=116
		Combine input records=12
		Combine output records=9
		Reduce input groups=9
		Reduce shuffle bytes=106
		Reduce input records=9
		Reduce output records=9
		Spilled Records=18
		Shuffled Maps =1
		Failed Shuffles=0
		Merged Map outputs=1
		GC time elapsed (ms)=88
		CPU time spent (ms)=890
		Physical memory (bytes) snapshot=513982464
		Virtual memory (bytes) snapshot=4242575360
		Total committed heap usage (bytes)=316145664
	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=59
	File Output Format Counters 
		Bytes Written=64

  • 查看结果
    hdfs dfs -ls output
Found 2 items
-rw-r--r--   1 root supergroup          0 2018-11-08 16:19 output1/_SUCCESS
-rw-r--r--   1 root supergroup         64 2018-11-08 16:19 output1/part-r-00000

hdfs dfs -cat output/part-r-00000

Beijing	2
China	2
I	2
capital	1
is	1
love	2
of	1
the	1

-下载到本地output目录看结果
hdfs dfs -get output output
cat ouput/part-r-00000
输出同样的结果

二、hdfs常用命令

图中显示了很多命令选项信息。以上截图不全,我在表格4-1中完整地列出了支持的命令选项。

选项名称 使用格式 含义
-ls -ls <路径> 查看指定路径的当前目录结构
-lsr -lsr <路径> 递归查看指定路径的目录结构
-du -du <路径> 统计目录下个文件大小
-dus -dus <路径> 汇总统计目录下文件(夹)大小
-count -count [-q] <路径> 统计文件(夹)数量
-mv -mv <源路径><目的路径> 移动
-cp -cp <源路径> <目的路径> 复制
-rm -rm [-skipTrash] <路径> 删除文件/空白文件夹
-rmr -rmr [-skipTrash] <路径> 递归删除
-put -put <多个linux上的文件> <hdfs路径> 上传文件
-copyFromLocal -copyFromLocal <多个linux上的文件> <hdfs路径> 从本地复制
-moveFromLocal -moveFromLocal <多个linux上的文件> <hdfs路径> 从本地移动
-getmerge -getmerge <源路径> <linux路径> 合并到本地
-cat -cat <hdfs路径> 查看文件内容
-text -text <hdfs路径> 查看文件内容
-copyToLocal -copyToLocal [-ignoreCrc] [-crc] [hdfs源路径] [linux目的路径] 从本地复制
-moveToLocal -moveToLocal [-crc] <hdfs源路径> <linux目的路径> 从本地移动
-mkdir -mkdir <hdfs路径> 创建空白文件夹
-setrep -setrep [-R] [-w] <副本数> <路径> 修改副本数量
-touchz -touchz <文件路径> 创建空白文件
-stat -stat [format] <路径> 显示文件统计信息
-tail -tail [-f] <文件> 查看文件尾部信息
-chmod -chmod [-R] <权限模式> [路径] 修改权限
-chown -chown [-R] [属主][:[属组]] 路径 修改属主
-chgrp -chgrp [-R] 属组名称 路径 修改属组
-help -help [命令选项] 帮助

注意:以上表格中路径包括hdfs中的路径和linux中的路径。对于容易产生歧义的地方,会特别指出“linux路径”或者“hdfs路径”。如果没有明确指出,意味着是hdfs路径。