问题描述

来自 本指南，我已经成功运行了示例练习.但是在运行我的 mapreduce 作业时，我收到以下错误
ERROR streaming.StreamJob:作业不成功！
2016 年 10 月 12 日 17:13:38 信息流.StreamJob:killJob...
流式传输作业失败！
来自日志文件的错误

From this guide, I have successfully run the sample exercise. But on running my mapreduce job, I am getting the following error
ERROR streaming.StreamJob: Job not Successful!
10/12/16 17:13:38 INFO streaming.StreamJob: killJob...
Streaming Job Failed!
Error from the log file

java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 2
at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:311)
at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:545)
at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:132)
at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:57)
at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:358)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:307)
at org.apache.hadoop.mapred.Child.main(Child.java:170)

映射器.py

import sys

i=0

for line in sys.stdin:
    i+=1
    count={}
    for word in line.strip().split():
        count[word]=count.get(word,0)+1
    for word,weight in count.items():
        print '%s	%s:%s' % (word,str(i),str(weight))

reducer.py

Reducer.py

import sys

keymap={}
o_tweet="2323"
id_list=[]
for line in sys.stdin:
    tweet,tw=line.strip().split()
    #print tweet,o_tweet,tweet_id,id_list
    tweet_id,w=tw.split(':')
    w=int(w)
    if tweet.__eq__(o_tweet):
        for i,wt in id_list:
            print '%s:%s	%s' % (tweet_id,i,str(w+wt))
        id_list.append((tweet_id,w))
    else:
        id_list=[(tweet_id,w)]
        o_tweet=tweet

[edit] 运行作业的命令:

[edit] command to run the job:

hadoop@ubuntu:/usr/local/hadoop$ bin/hadoop jar contrib/streaming/hadoop-0.20.0-streaming.jar -file /home/hadoop/mapper.py -mapper /home/hadoop/mapper.py -file /home/hadoop/reducer.py -reducer /home/hadoop/reducer.py -input my-input/* -output my-output

输入是任意随机序列的句子.

Input is any random sequence of sentences.

谢谢，

推荐答案

你的 -mapper 和 -reducer 应该只是脚本名称.

Your -mapper and -reducer should just be the script name.

hadoop@ubuntu:/usr/local/hadoop$ bin/hadoop jar contrib/streaming/hadoop-0.20.0-streaming.jar -file /home/hadoop/mapper.py -mapper mapper.py -file /home/hadoop/reducer.py -reducer reducer.py -input my-input/* -output my-output

当您的脚本位于 hdfs 内另一个文件夹中的作业中时，该作业与执行为."的尝试任务相关.(仅供参考，如果您想要添加另一个文件，例如查找表，您可以在 Python 中打开它，就好像它与您的脚本在同一目录中一样，而您的脚本在 M/R 作业中)

When your scripts are in the job that is in another folder within hdfs which is relative to the attempt task executing as "." (FYI if you ever want to ad another -file such as a look up table you can open it in Python as if it was in the same dir as your scripts while your script is in M/R job)

还要确保你有 chmod a+x mapper.py 和 chmod a+x reducer.py

also make sure you have chmod a+x mapper.py and chmod a+x reducer.py

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