Hadoop MapReduce Wordcount python 执行错误

Question

我正在尝试执行 python MapReduce wordcount 程序

我取自writing a Hadoop MapReduce program in python 只是想了解它是如何工作的，但问题总是作业不成功！

我在 Cloudera VM

中使用这个库执行 mapper.py 和 reducer.py

/usr/lib/hadoop-0.20-mapreduce/contrib/streaming/hadoop-streaming-2.6.0-mr1-cdh5.12.0.jar

执行命令：

hadoop jar /usr/lib/hadoop-0.20-mapreduce/contrib/streaming/hadoop-streaming-2.6.0-mr1-cdh5.12.0.jar
-Dmaperd.reduce, tasks=1
-file wordcount/mapper.py 
-mapper mapper.py -file wordcount/reducer.py
-reducer reducer.py
-input myinput/test.txt
-output output

Answer 1

问题出在文件 mapper.py 的路径上，reducer.py 必须来自本地

但输入文件必须来自 hdfs 路径

首先，必须使用

在本地测试 python 代码

cat <input file> | python <path from>/mapper.py | python <path from local>/reducer.py

然后在 hdfs

hadoop jar /usr/lib/hadoop-0.20-mapreduce/contrib/streaming/hadoop-streaming-2.6.0-mr1-cdh5.12.0.jar 

-Dmaperd.reduce,tasks=1 -file <path of local>/mapper.py 

-mapper "python <path from local>/mapper.py" 

-file <path from local>/reducer.py -

reducer "python <path of local>/reducer.py" 

-input <path from hdfs>/myinput/test.txt 

-output output

Hadoop MapReduce Wordcount python 执行错误

Hadoop MapReduce Wordcount python execution error

python

hadoop

mapreduce

cloudera

word-count