How can I include a python package with Hadoop streaming job?
I am trying include a python package (NLTK) with a Hadoop streaming job, but am not sure how to do this without including every file manually via the CLI argument, "-file".
Edit: One solution would be to install this package on all the slaves, but I don't have that option currently开发者_高级运维.
Just came across this gem of a solution: http://blog.cloudera.com/blog/2008/11/sending-files-to-remote-task-nodes-with-hadoop-mapreduce/
first create zip w/ the libraries desired
zip -r nltkandyaml.zip nltk yaml
mv ntlkandyaml.zip /path/to/where/your/mapper/will/be/nltkandyaml.mod
next, include via Hadoop stream "-file" argument:
hadoop -file nltkandyaml.zip
finally, load the libaries via python:
import zipimport
importer = zipimport.zipimporter('nltkandyaml.mod')
yaml = importer.load_module('yaml')
nltk = importer.load_module('nltk')
Additionally, this page summarizes how to include a corpus: http://www.xcombinator.com/2009/11/18/how-to-use-cascading-with-hadoop-streaming/
download and unzip the wordnet corpus
cd wordnet
zip -r ../wordnet-flat.zip *
in python:
wn = WordNetCorpusReader(nltk.data.find('lib/wordnet-flat.zip'))
I would zip up the package into a .tar.gz
or a .zip
and pass the entire tarball or archive in a -file
option to your hadoop command. I've done this in the past with Perl but not Python.
That said, I would think this would still work for you if you use Python's zipimport
at http://docs.python.org/library/zipimport.html, which allows you to import modules directly from a zip.
You can use zip lib like this:
import sys
sys.path.insert(0, 'nltkandyaml.mod')
import ntlk
import yaml
An example of loading external python package nltk
refer to the answer
Running extrnal python lib like (NLTK) with hadoop streaming
I followed following approach and ran the nltk package in with hadoop streaming successfully.
Assumption, you have already your package or (nltk in my case)in your system
first:
zip -r nltk.zip nltk
mv ntlk.zip /place/it/anywhere/you/like/nltk.mod
Why any where will work?
Ans :- Because we will provide path to this .mod zipped file through command line, we don't need to worry much about it.
second:
changes in your mapper or .py file
#Hadoop cannot unzip files by default thus you need to unzip it
import zipimport
importer = zipimport.zipimporter('nltk.mod')
nltk = importer.load_module('nltk')
#now import what ever you like from nltk
from nltk import tree
from nltk import load_parser
from nltk.corpus import stopwords
nltk.data.path += ["."]
third: command line argument to run map-reduce
hadoop jar /usr/lib/hadoop-mapreduce/hadoop-streaming.jar \
-file /your/path/to/mapper/mapper.py \
-mapper '/usr/local/bin/python3.4 mapper.py' \
-file /your/path/to/reducer/reducer.py \
-reducer '/usr/local/bin/python3.4 reducer.py' \
-file /your/path/to/nltkzippedmodfile/nltk.mod \
-input /your/path/to/HDFS/input/check.txt -output /your/path/to/HDFS/output/
Thus, above step solved my problem and I think it should solve others as well.
cheers,
If you are using much more complex libs such as numpy、pandas, virtualenv is a better way. You can add -archives to send the env to cluster.
Refer to the writing: https://henning.kropponline.de/2014/07/18/virtualenv-hadoop-streaming/
Updated:
I tried above virtualenv in our online env, and find some problems.In the cluster,there is some errors like "Could not find platform independent libraries "。Then i tried the conda to create python env, it worked well.
If you are Chinese, you can look this:https://blog.csdn.net/Jsin31/article/details/53495423
If not, i can translate it briefly:
create an env by conda:
conda create -n test python=2.7.12 numpy pandas
Go to the conda env path.You can find it by cmd:
conda env list
Then,you can pack it:
tar cf test.tar test
- submit the job through hadoop stream:
hadoop jar /usr/lib/hadoop/hadoop-streaming.jar \
-archives test.tar \
-input /user/testfiles \
-output /user/result \
-mapper "test.tar/test/bin/python mapper.py" \
-file mapper.py \
-reducer"test.tar/test/bin/python reducer.py" \
-file reducer.py
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