This seems to be a minimal program to reproduce the problem:


import sys
import os
import platform

platform.mac_ver()

if sys.version_info[0] == 2:
    import urllib
else:
    import urllib.request

if os.fork() == 0:
    print ("about to call getproxies !")
    if sys.version_info[0] == 2:
        print (urllib.getproxies())
    else:
        print (urllib.request.getproxies())
    print ("getproxies has completed !")

else:
    os.wait()

The call to platform.mac_ver is essential, without that call the problem goed away.

This explains why my 2.7 build doesn't crash: I've committed a patch at the EuroPython sprints that replaces the platform.mac_ver implementation by one that reads the OSX version from an XML file instead of calling low-level Apple APIs, and those lowlevel APIs somehow cause the breakage (see also issue #7895)

This means that the problem should go away in the next release for all branches.

mike: are you able to test if the problem goes away when you build python from source using a subversion checkout?



Note that this doesn't mean that the underlying problem is gone, you'll probably still run into problems when the main program is a GUI program that using multiprocessing to start work in the background.