>> >> Simply because the concurrent future returned by executor.submit does >> not implement __await__ and so it cannot be awaited for. > I get that, but what happens if you try wrapping the executor.submit > call with tornado.gen.convert_yielded as the tornado docs suggest and > as I suggested above? Thanks, it did the right thing. :-) (The tornado docs needs to be updated where it talks about changing normal coroutines to native coroutines.)
>> Of course, asyncio should not care if the executor is doing the task in >> a different thread or a different process. All I'm saying is that >> concurrent.futures.Future should implement the __await__ method, and >> asyncio should be able to use it. > I found this in the original PEP at > http://legacy.python.org/dev/peps/pep-3156/#futures: > > """ > In the future (pun intended) we may unify asyncio.Future and > concurrent.futures.Future, e.g. by adding an __iter__() method to the > latter that works with yield from. To prevent accidentally blocking > the event loop by calling e.g. result() on a Future that's not done > yet, the blocking operation may detect that an event loop is active in > the current thread and raise an exception instead. However the current > PEP strives to have no dependencies beyond Python 3.3, so changes to > concurrent.futures.Future are off the table for now. > """ I was not aware of this. Thank you for pointing out. > > Maybe we're now far enough into the future that this could be > reconsidered. In the meantime, the user does have other options: > > 1) For tornado, use tornado.gen.convert_yielded. > > 2) For asyncio, create an asyncio future and link them by setting a > callback on the concurrent future that propagates the result (using > call_soon_threadsafe since the callback may run in another thread). > > 3) Better, don't use concurrent.futures directly in the first place; > instead use > https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.AbstractEventLoop.run_in_executor > which runs a function in an Executor and wraps it up via #2 > transparently. That is the best. I have discovered another anomaly: asyncio names this "run_in_executor" but tornado names it "run_on_executor" ( http://www.tornadoweb.org/en/stable/concurrent.html#tornado.concurrent.run_on_executor ) I hope eventually they will become fully compatible. :-) Thanks for your help! Laszlo -- https://mail.python.org/mailman/listinfo/python-list
