> An there you have the answer. It's really very simple :-) I'm fairly skeptical that it actually works. If the different Python interpreters all import the same extension module (say, _socket.pyd), windows won't load the DLL twice, but only one time. So you end up with a single copy of _socket, which will have a single copy of socket.error, socket.socket, and so on.
The single copy of socket.error will inherit from one specific copy of IOError. So if you import socket in a different interpreter, and raise socket.error there, and try to catch IOError, the exception won't be caught - because *that* IOError is then not a base class of socket.error. A more general approach similar to this one is known as ".NET appdomains" or "Java isolates". It requires the VM to refrain from having any global state, and to associate all "global" state with the appdomain or isolate. Python can't easily support that kind of model, because extension modules have global state all the time. Even if Python supported appdomains, you still wouldn't get any object sharing out of it. As soon as you start to share some object (but not their types), your entire type hierarchy gets messed up. FWIW, Tcl implements this model precisely: Tcl is not thread-safe in itself, but supports a interpreter-per-thread model. I'm also skeptical that this is any better than the GIL. Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
