Python API, objects, globals, and forking.

[David M. Wilson]

Hello,

I have a C program embedding the Python interpreter, and loading a new
module like so:

   exim_module = PyImport_ExecCodeModule("__exim__", compiled_module);


The program then forks a little while later, PyOS_AfterFork() gets
called, and everything appears to be honkey dory. However, given the
__exim__ module of:

    foo = 1

    def a():
        print foo

    def b():
        print foo


When the program calls a(), "1" is printed as expected, but on the
second Python function call, "None" would be printed. Both calls occur
after the fork. Looking at globals(), all my user objects (foo, etc.)
are set to None, with the only object remaining untouched being
__builtins__. Interestingly, even the active function's reference in
globals() is set to None - suggesting the change occurs after my C
program does:

   while (...)
      root = PyObject_GetAttrString(last, pos);
      /* succeeds in looking up the b() function object. */

   ...

   result = PyObject_Call(callable, py_args, NULL);


The only other Python API calls I make in between these two are
PyTuple_New, PyTuple_SET_ITEM, PyObject_DECREF, and
PyString_FromString.

Stuffing some user variables into __builtins__ and testing for them
later appears to work - so it looks like something is specifically
cleaning out the globals. Can someone shed any light on this?


David.