debug reload no work

[tkzczen]

import asyncio
import tornado


class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world")


settings = {
    'template_path':'template',
    'static_path': 'static',
    'debug':True,
}

def make_app():
    return tornado.web.Application([
        (r"/", MainHandler),
        (r"/run", MainHandler1),
    ],**settings)

async def main():
    app = make_app()
    app.listen(2022)
    await asyncio.Event().wait()

if __name__ == "__main__":
    asyncio.run(main())

[yelinaung]

@tkzczen Let's say if you add something like this

if __name__ == "__main__":
    import time
    print(f"Starting at {time.strftime('%X %x %Z')}")
    app = make_app()
    app.listen(2022)
    tornado.ioloop.IOLoop.current().start()

and you save the files a few times, do you see the timestamp change ? (example on my system)

❯ uv run app.py
Starting at 22:24:02 02/15/25 +08
Starting at 22:24:09 02/15/25 +08
Starting at 22:24:10 02/15/25 +08
Starting at 22:24:11 02/15/25 +08

[bdarnell]

How exactly are you running this program? Which version of python, tornado, etc? The sample is incomplete (undefined reference to MainHandler1); is anything else missing?

[tkzczen]

How exactly are you running this program? Which version of python, tornado, etc? The sample is incomplete (undefined reference to MainHandler1); is anything else missing?

• python 3.8.10
• tornado 6.4.2

Before this , I used set settings = { 'debug':True}, The web server been auto restart the code when I change the web server code.But Now, I use asyncio and change web sever code,the sever not auto restart,every time I must close the program and run again.

[bdarnell]

How exactly are you running it? Just python3 app.py? Something integrated into your editor? (Pycharm users have reported problems with autoreload, but since I don't use pycharm I don't know anything about that: #2243)

What platform? I'm not sure how well autoreload works on windows. Very old versions of MacOS used to have problems too but as far as I know that was fixed many years ago.

It's possible that you're hitting an error before the autoreload starts: If you use the code above you'll get an error for the undefined reference to MainHandler1, and because this is before the app is started with debug=True, it won't go into autoreload mode. To fix this, you need to use the autoreload command-line wrapper: python3 -m tornado.autoreload app.py.

[tkzczen]

How exactly are you running it? Just python3 app.py? Something integrated into your editor? (Pycharm users have reported problems with autoreload, but since I don't use pycharm I don't know anything about that: #2243)

What platform? I'm not sure how well autoreload works on windows. Very old versions of MacOS used to have problems too but as far as I know that was fixed many years ago.

It's possible that you're hitting an error before the autoreload starts: If you use the code above you'll get an error for the undefined reference to MainHandler1, and because this is before the app is started with debug=True, it won't go into autoreload mode. To fix this, you need to use the autoreload command-line wrapper: python3 -m tornado.autoreload app.py.

I found that the web did not restart due to a problem with my code. In my other code, it is not the same as the example above. I will modify it to tornado.web Application was set as a variable and then returned with a method, causing debug to not work. I modified the code and now the problem is solved. The original error code is as follows.

application = tornado.web.Application([
        (r"/", MainHandler),
        (r"/run", MainHandler1),
    ],**settings)
def make_app():
    return application

async def main():
    app = make_app()
    app.listen(2022)
    await asyncio.Event().wait()

There are no more issues now