Question

我试图按照此页面上的说明操作： http://www.michael-noll.com/tutorials/writing-an-hadoop-mapreduce-program-in-python/

$bin/hadoop jar contrib/streaming/hadoop-streaming-1.0.4.jar -input /user/root/wordcountpythontxt -output /user/root/wordcountpythontxt-output -mapper /user/root/wordcountpython/mapper.py -reducer /user/root/wordcountpython/reducer.py -file /user/root/mapper.py -file /user/root/reducer.py

它说

File: /user/root/mapper.py does not exist, or is not readable.
Streaming Command Fail

当我浏览网址时：jobdetails.jsp /

我发现很多例外

java.lang.RuntimeException: Error in configuring object
    at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:93)
    at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:64)
    at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117)
    at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:432)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:372)
    at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:396)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
    at org.apache.hadoop.mapred.Child.main(Child.java:249)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:88)
    ... 9 more
Caused by: java.lang.RuntimeException: Error in configuring object
    at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:93)
    at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:64)
    at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117)
    at org.apache.hadoop.mapred.MapRunner.configure(MapRunner.java:34)
    ... 14 more
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:88)
    ... 17 more
Caused by: java.lang.RuntimeException: configuration exception
    at org.apache.hadoop.streaming.PipeMapRed.configure(PipeMapRed.java:230)
    at org.apache.hadoop.streaming.PipeMapper.configure(PipeMapper.java:66)
    ... 22 more
Caused by: java.io.IOException: Cannot run program "/user/root/wordcountpython/mapper.py": error=2, No such file or directory
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:460)
    at org.apache.hadoop.streaming.PipeMapRed.configure(PipeMapRed.java:214)
    ... 23 more
Caused by: java.io.IOException: error=2, No such file or directory
    at java.lang.UNIXProcess.forkAndExec(Native Method)
    at java.lang.UNIXProcess.<init>(UNIXProcess.java:53)
    at java.lang.ProcessImpl.start(ProcessImpl.java:91)
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:453)
    ... 24 more

我无法修复它请帮助我运行python pgm。

Answer 1

如果您在link上仔细查看说明，

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

它清楚地表明没有必要将mapper.py和reducer.py复制到HDFS，你可以链接来自本地文件系统的两个文件：as / path / to / mapper。我相信你可以避免上述错误。

Answer 2

你可能想要在＃之后检查你没有dos风格的新行！ mapper.py中的行。如果你这样做，hadoop可能无法找到你的python解释器，因为它会看到额外的CR。例如。 / usr / local / bin / python ^ M而不是/ usr / local / bin / python其中^ M是CR。在mapper和reducer上尝试dos2unix命令。

Answer 3

似乎问题在线。

Caused by: java.io.IOException: Cannot run program "/user/root/wordcountpython/mapper.py": error=2, No such file or directory

请检查文件/user/root/wordcountpython/mapper.py是否存在。如果它存在，那么该文件的权限是什么。

运行hadoop的用户是否有权执行和读取此文件？

在Hadoop上运行Python代码失败

3 个答案: