RequestHandler.finish() future not resolving

[sbrandtb]

Just tried Tornado 5.1 for the first time and am wondering if I'm doing something wrong when waiting for the future of the finish method:

import tornado.ioloop
import tornado.web

class MainHandler(tornado.web.RequestHandler):
    async def get(self):
        print('before')
        await self.finish("Hello, world")
        print('after')

def make_app():
    return tornado.web.Application([
        (r"/", MainHandler),
    ])

if __name__ == "__main__":
    app = make_app()
    app.listen(8888)
    tornado.ioloop.IOLoop.current().start()

It seems like the future is never resolved. after is not printed and interrupting the application outputs:

KeyboardInterrupt
ERROR:asyncio:Task was destroyed but it is pending!
task: <Task pending coro=<MainHandler.get() running at main.py:7> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f0cb0b25e28>()]> cb=[IOLoop.add_future.<locals>.<lambda>() at /home/sebastian/.virtualenvs/tempenv-2fc3210213e1f/lib/python3.6/site-packages/tornado/ioloop.py:719]>

Python 3.6, Ubuntu

[garenchan]

I give a PR to solve this problem in #2449.

[sbrandtb]

@garenchan Thanks!

[bdarnell]

Fixed by #2449

[cramosc]

@garenchan This bug hasn't been completely fixed in #2449
If you try with the following modification of the code above, the future RequestHandler.finish() is still not resolving

import tornado.ioloop
import tornado.web


class MainHandler(tornado.web.RequestHandler):
    async def get(self):
        self.write('first')
        await self.flush('first')
        print('before finish')
        await self.finish('second')
        print('finished')


def make_app():
    return tornado.web.Application([
        (r"/", MainHandler),
    ])


if __name__ == "__main__":
    app = make_app()
    app.listen(8888)
    tornado.ioloop.IOLoop.current().start()

The fix on HTTP1Connection.write_headers() should also be applied to HTTP1Connection.write() since the latter is the one called in the second call to RequestHandler.flush() (after the headers have been written).

[garenchan]

@cramosc, Thank you very much! You are right and I left out the changes to the other branch.