I'm trying to get python-gasp working on Windows, but when I do import gasp; gasp.begin_graphics() I get the following traceback:
File "C:\Python26\lib\site-packages\gasp\backend.py", line 142, in create_screen
screen.updater.start()
File "C:\Python26\lib\multiprocessing\process.py", line 104, in start
self._popen = Popen(self)
File "C:\Python26\lib\multiprocessing\forking.py", line 239, in __init__
dump(process_obj, to_child, HIGHEST_PROTOCOL)
File "C:\Python26\lib\multiprocessing\forking.py", line 162, in dump
ForkingPickler(file, protocol).dump(obj)
File "C:\Python26\lib\pickle.py", line 224, in dump
self.save(obj)
File "C:\Python26\lib\pickle.py", line 331, in save
self.save_reduce(obj=obj, *rv)
File "C:\Python26\lib\pickle.py", line 419, in save_reduce
save(state)
File "C:\Python26\lib\pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "C:\Python26\lib\pickle.py", line 649, in save_dict
self._batch_setitems(obj.iteritems())
File "C:\Python26\lib\pickle.py", line 681, in _batch_setitems
save(v)
File "C:\Python26\lib\pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "C:\Python26\lib\pickle.py", line 725, in save_inst
save(stuff)
File "C:\Python26\lib\pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "C:\Python26\lib\pickle.py", line 649, in save_dict
self._batch_setitems(obj.iteritems())
File "C:\Python26\lib\pickle.py", line 681, in _batch_setitems
save(v)
File "C:\Python26\lib\pickle.py", line 331, in save
self.save_reduce(obj=obj, *rv)
File "C:\Python26\lib\pickle.py", line 396, in save_reduce
save(cls)
File "C:\Python26\lib\pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "C:\Python26\lib\pickle.py", line 748, in save_global
(obj, module, name))
PicklingError: Can't pickle <class 'multiprocessing.process._MainProcess'>: it's not found as multiprocessing.process._MainProcess
Any idea why I'm getting this error on Windows XP but not on Ubuntu Linux 9.04?
It looks like screen.updater is an instance of Updater(multiprocessing.Process) (def), if that helps. The file in question is at http://bazaar.launchpad.net/~gasp-dev/gasp-core/main/annotate/head%3A/gasp/backend.py
Your Updater class has a member screen, which itself has a member process which receives the value of multiprocessing.current_process().
When you call updater.start(), it tries to pickle the updater. This only happens on Windows because Linux uses fork() instead of pickling. However, the current-process object cannot be pickled and the exception is raised.
To fix this, you can remove the process member.