mod_wsgi/python sys.path.exend problems

I'm working on a mod_wsgi script.. at the beginning is:

sys.path.extend(map(os.path.abspath, ['/media/server/www/webroot/']))

But I've noticed, that every time I update the script the sys.path var keeps growing with duplicates of this extension:

['/usr/lib64/python25.zip'
'/usr/lib64/python2.5'
'/usr/lib64/python2.5/plat-linux2'
'/usr/lib64/python2.5/lib-tk'
'/usr/lib64/python2.5/lib-dynload'
'/usr/lib64/python2.5/site-packages'
'/usr/lib64/python2.5/site-packages/Numeric'
'/usr/lib64/python2.5/site-packages/gtk-2.0'
'/usr/lib64/python2.5/site-packages/scim-0.1'
'/usr/lib/python2.5/site-packages'
'/media/server/www/webroot'
'/media/server/www/webroot'
'/media/server/www/webroot'
'/media/server/www/webroot']

It resets every time I restart apache.. is there any way to make sure this doesn't happen? I want the module path to be loaded only once..

From stackoverflow

• One fairly simple way to do this is to check to see if the path has already been extended before extending it::

  path_extension = map(os.path.abspath,['/media/server/www/webroot/']) 
  if path_extension[0] not in sys.path:
      sys.path.extend(path_extension)
  

  This has the disadvantage, however, of always scanning through most of sys.path when checking to see if it's been extended. A faster, though more complex, version is below::

  path_extension = map(os.path.abspath,['/media/server/www/webroot/']) 
  if path_extension[-1] not in reversed(sys.path):
      sys.path.extend(path_extension)
  

  A better solution, however, is probably to either add the path extensions to your PYTHONPATH environment variable or put a .pth file into your site-packages directory:

  http://docs.python.org/install/index.html

  David Berger : +1 .pth files are awesome. So are environment variables set from apache config.

• No need to worry about checking or using abspath yourself. Use the ‘site’ module's built-in addsitedir function. It will take care of these issues and others (eg. pth files) automatically:

  import site
  site.addsitedir('/media/server/www/webroot/')
  

  (This function is only documented in Python 2.6, but it has pretty much always existed.)

• The mod_wsgi documentation on code reloading covers this.