Hi Binglin, thanks for your explanation, now it makes sense. However, I'm not sure how to implement suggested method with.
First of all, I found out that `-cachArchive` option is deprecated, so I had to use `-archives` instead. I put my `lib.py` to directory `lib` and then zipped it to `lib.zip`. After that I uploaded archive to HDFS and linked it in call to Streaming API as follows: hadoop jar /usr/lib/hadoop-mapreduce/hadoop-streaming.jar -files main.py *-archives hdfs://hdfs-namenode/user/me/lib.jar* -mapper "./main.py map" -reducer "./main.py reduce" -combiner "./main.py combine" -input input -output output But script failed, and from logs I see that lib.jar hasn't been unpacked. What am I missing? On Mon, Aug 12, 2013 at 11:33 AM, Binglin Chang <decst...@gmail.com> wrote: > Hi, > > The problem seems to caused by symlink, hadoop uses file cache, so every > file is in fact a symlink. > > lrwxrwxrwx 1 root root 65 Aug 12 15:22 lib.py -> > /root/hadoop3/data/nodemanager/usercache/root/filecache/13/lib.py > lrwxrwxrwx 1 root root 66 Aug 12 15:23 main.py -> > /root/hadoop3/data/nodemanager/usercache/root/filecache/12/main.py > [root@master01 tmp]# ./main.py > Traceback (most recent call last): > File "./main.py", line 3, in ? > import lib > ImportError: No module named lib > > This should be a python bug: when using import, it can't handle symlink > > You can try to use a directory containing lib.py and use -cacheArchive, > so the symlink actually links to a directory, python may handle this case > well. > > Thanks, > Binglin > > > > On Mon, Aug 12, 2013 at 2:50 PM, Andrei <faithlessfri...@gmail.com> wrote: > >> (cross-posted from >> StackOverflow<http://stackoverflow.com/questions/18150208/how-to-import-custom-module-in-mapreduce-job?noredirect=1#comment26584564_18150208> >> ) >> >> I have a MapReduce job defined in file *main.py*, which imports module >> lib from file *lib.py*. I use Hadoop Streaming to submit this job to >> Hadoop cluster as follows: >> >> hadoop jar /usr/lib/hadoop-mapreduce/hadoop-streaming.jar >> >> -files lib.py,main.py >> -mapper "./main.py map" -reducer "./main.py reduce" >> -input input -output output >> >> In my understanding, this should put both main.py and lib.py into >> *distributed >> cache folder* on each computing machine and thus make module lib available >> to main. But it doesn't happen - from log file I see, that files *are >> really copied* to the same directory, but main can't import lib, throwing >> *ImportError*. >> >> Adding current directory to the path didn't work: >> >> import sys >> sys.path.append(os.path.realpath(__file__))import lib# ImportError >> >> though, loading module manually did the trick: >> >> import imp >> lib = imp.load_source('lib', 'lib.py') >> >> But that's not what I want. So why Python interpreter can see other .py >> files >> in the same directory, but can't import them? Note, I have already tried >> adding empty __init__.py file to the same directory without effect. >> >> >> >
