Tornado: asyncio.wait_for not working

[argaen]

Hi, I know there are some incompatibilities with asyncio and I'm writing here to double check. I have the following code that is hanging indefinitely in python3.5.2 and also in python3.6.0b3:

import asyncio
import tornado.web
import tornado.ioloop
from datetime import datetime

class MainHandler(tornado.web.RequestHandler):

    async def time(self):
        return datetime.now().isoformat()

    async def get(self):
        await asyncio.wait_for(self.time(), 5)     # Here I'll hang
        self.write(await self.time())


if __name__ == "__main__":
    tornado.ioloop.IOLoop.configure('tornado.platform.asyncio.AsyncIOLoop')
    app = tornado.web.Application([(r"/", MainHandler)])
    app.listen(8888)
    tornado.ioloop.IOLoop.current().start()

is this expected behavior? I'm maintaining https://github.com/argaen/aiocache and would like to support asyncio Tornado too.

Thanks

[argaen]

Looks like with Python 3.6.0+ (3.6:ea87e00a3e89, Dec 28 2016, 12:22:26) works

[jonathansp]

Just realized that it has also happened with aioredis.

[dpereira]

Looks like to be caused by the same reason as #1543

[bdarnell]

I think this is a bit different from #1543. That issue is about the differences between the tornado and asyncio event loops (tornado allows a loop to be closed while running, but asyncio doesn't). This looks like the difference between AsyncIOMainLoop and AsyncIOLoop. I think you almost always want to use AsyncIOMainLoop. Tornado 5.0 will default to asyncio when available and include other changes to reduce this friction.

[bdarnell]

The changes to unify the two event loops for Tornado 5.0 are complete (in the master branch). Now this example should just work without doing anything to configure the IOLoop.