[Python-Dev] Better module shutdown procedure

[Neil Schemenauer]

The current shutdown code in pythonrun.c zaps module globals by
setting them to None (an attempt to break reference cycles). That
causes problems since __del__ methods can try to use the globals
after they have been set to None.

The procedure implemented by http://bugs.python.org/issue812369
seems to be a better idea. References to modules are replaced by
weak references and the GC is allowed to cleanup reference cycles.

I would like to commit this change but I'm not sure if it is a good
time in the development cycle or if anyone has objections to the
idea. Please speak up if you have input.

  Neil