Python read file as stream from HDFS

Question

I have a python read file in HDFS which I need to run, but due to some reasons or issues in my HDFS, I am unable to run it. I am getting a warning which says not enough to fit all in memory.

I wish to clear all cache and process this read file. I am searching for a method to do it without using any of the additional libraries. I was thinking to do this using the standard "Hadoop" command line tools using the Python subprocess module, but I can't seem to be able to do what I need since there are no command line tools that would do my processing and I would like to execute a Python function for every line in a streaming fashion.

Is there a way to apply Python functions as right operands of the pipes using the subprocess module? Or even better, open it like a file as a generator so I could process each line easily?

Answer 1

I could redirect to a Python library which should help you fix the issue If it does not work, then, I can suggest you get the stdout pipe from your Popen object. 

#cat = subprocess.Popen(["hadoop", "fs", "-cat", "/path/to/myfile"], stdout=subprocess.PIPE)
#for line in cat.stdout:
#print line