I've taken over somebody's code for a fairly large project. I'm trying to save program state, and there's one massive object which stores pretty much all the other objects. I'm trying to pickle this object, but I get this error:

pickle.PicklingError: Can't pickle : it's not found as builtin.module

From what I can find on google, this is because somewhere I'm importing something outside of python init, or that a class attribute is referencing a module. So, I've got a two questions:

1. Can anybody confirm that that's why this error is being given? Am I looking for the right things in my code?

2. Is there a way to find what line of code/object member is causing the difficulties in pickle? The traceback only gives the line in pickle where the error occurs, not the line of the object being pickled.

2) You can subclass pickle.Pickler and monkey-patch it to show a log of what it's pickling. This should make it easier to trace where the problem is.

import pickle
class MyPickler (pickle.Pickler):def save(self, obj):print 'pickling object', obj, 'of type', type(obj)pickle.Pickler.save(self, obj)

This will only work with the Python implementation of pickle.Pickler. In Python 3.x, the pickle module uses the C implementation by default, the pure-Python version of Pickler is called _Pickler.

# Python 3.x
import pickle
class MyPickler (pickle._Pickler):def save(self, obj):print ('pickling object  {0} of type {1}'.format(obj, type(obj))pickle._Pickler.save(self, obj)