How can I include a python package with Hadoop streaming job?

Question

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\"

Answer 1

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,

Answer 2

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:

1. create an env by conda：

   conda create -n test python=2.7.12 numpy pandas

2. 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

3. 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

Answer 3

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.

Answer 4

You can use zip lib like this:

import sys
sys.path.insert(0, 'nltkandyaml.mod')
import ntlk
import yaml

Answer 5

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'))