It is blocking, but this reminded me of a kind of a neat little wrapper I guy I know put around gevent, which fell back to eventlet, and then threads if neither of those two were present. You can add functions to data structures that resemble either dicts or lists and as soon as the functions are added they are executed in the background and have the values returned from the functions be available in place of the functions as soon as they're done executing. It's here.
