Several places in the documentation claim that Py_Finalize will release all memory: http://docs.python.org/api/embedding.html says that literally, and http://docs.python.org/api/initialization.html#l2h-778 suggests it is a bug when memory is not freed in Py_Finalize. This has left people to believe that this is a bug: https://sourceforge.net/tracker/index.php?func=detail&aid=1445210&group_id=5470&atid=105470 However, I don't see any chance to make this promise even remotely. Objects allocated in extension modules, and held in global variables (e.g. socketmodule.c:socket_error, socket_herror, socket_gaierror, socket_timeout) will never be released, right? And because of the small objects allocator, their pool will remain allocated, right? And, then, the arena. So ISTM that invoking Py_Finalize after importing socket will yield atleast 256KiB garbage. Of course, that's not real garbage, because the next Py_Initialize'd interpreter will continue to allocate from the arenas. But still, the actual objects that the modules hold on to will not be reclaimed until the process terminates. Please correct me if I'm wrong. Regards, Martin