This is an implementation of InterpreterPoolExecutor that builds on ThreadPoolExecutor.
(Note that this is not tied to PEP 734, which is strictly about adding a new stdlib module.)
Possible future improvements:
* support passing a script for the initializer or to submit()
* support passing (most) arbitrary functions without pickling
* support passing closures
* optionally exec functions against __main__ instead of the their original module
Future.set_result and Future.set_exception now raise InvalidStateError
if the futures are not pending or running. This mirrors the behavior
of asyncio.Future, and prevents AssertionErrors in asyncio.wrap_future
when set_result is called multiple times.
Eric Snow