Question

I use subprocess.Popen in one of the my views:

path = os.path.join(os.path.dirname(__file__), 'foo/bar.py')
subprocess.Popen(["python",path])

In my wsgi file, I have

import os
import sys

ppath = '/home/socialsense/ss/src'
if ppath not in sys.path:
        sys.path.append(ppath)

os.environ['DJANGO_SETTINGS_MODULE'] = 'ss.settings'

import django.core.handlers.wsgi
application = django.core.handlers.wsgi.WSGIHandler()

and under src i have ss, my django project.

But when I check my log file, bar.py encountered an error, ImportError: No module named ss.discovery.models. Now it seems that the module ss itself is not in sys.path when using Popen…

anything i did wrongly here?

Answer 1

It will only be in sys.path for the current Python instance. To get it for another, use the env argument to Popen with os.pathsep:

import subprocess
import os
import sys
subprocess.Popen(["python",path], env = {'PYTHONPATH': os.pathsep.join(sys.path)})

You should really look into the multiprocessing module for running multiple instances of Python.

Edit: @Graham pointed out in a comment that you might want to run this external script with a different version of Python than the one you’re calling it from. That sounds unlikely to me, but if so, you’d need most of PYTHONPATH to be different for it to work, so you’d need to just add /home/socialsense/ss/src.