OpenCV imread hanging when called from a web request

Question

This is probably one of the strangest errors that I have ever ran into when using OpenCV. There is a lot going on, so let me try to explain this to the best of my ability.

Answer 1

Wrong

imagePath = os.path.dirname(__file__) + "/1.jpg"

Right

from os.path import abspath, join, dirname

imagePath = abspath( join(dirname(__file__), "1.jpg") )

Answer 2

I had a similar issue and found a fix -> just add to your apache configuration:

WSGIScriptAlias application-group=%{GLOBAL}

Apparently it happens when you have an extension module not designed to work in sub interpreter. The above forces it to run in main interpreter.

Sources: django apache mod-wsgi hangs on importing a python module from .so file http://blog.rtwilson.com/how-to-fix-flask-wsgi-webapp-hanging-when-importing-a-module-such-as-numpy-or-matplotlib/