quart/lobby

Discussion of Quart and related topics

Jorge Escobar

@esfoobar

Hi @pgjones -- I've been dealing with a very weird issue with the SSE application I mentioned earlier. The whole code is here: https://github.com/esfoobar/quart-feed. But what's happening is that once I get into the SSE page (the home page) and I reload several times manually, I eventually get to this error:

ages/aiomysql/cursors.py", line 457, in _query
quartfeed_web_1 |     await conn.query(q)
quartfeed_web_1 |   File "/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/aiomysql/connection.py", line 428, in query
quartfeed_web_1 |     await self._read_query_result(unbuffered=unbuffered)
quartfeed_web_1 |   File "/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/aiomysql/connection.py", line 622, in _read_query_result
quartfeed_web_1 |     await result.read()
quartfeed_web_1 |   File "/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/aiomysql/connection.py", line 1105, in read
quartfeed_web_1 |     first_packet = await self.connection._read_packet()
quartfeed_web_1 |   File "/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/aiomysql/connection.py", line 561, in _read_packet
quartfeed_web_1 |     packet_header = await self._read_bytes(4)
quartfeed_web_1 |   File "/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/aiomysql/connection.py", line 598, in _read_bytes
quartfeed_web_1 |     data = await self._reader.readexactly(num_bytes)
quartfeed_web_1 |   File "/usr/local/lib/python3.8/asyncio/streams.py", line 723, in readexactly
quartfeed_web_1 |     await self._wait_for_data('readexactly')
quartfeed_web_1 |   File "/usr/local/lib/python3.8/asyncio/streams.py", line 503, in _wait_for_data
quartfeed_web_1 |     raise RuntimeError(
quartfeed_web_1 | RuntimeError: readexactly() called while another coroutine is already waiting for incoming data

Any ideas why this is happening?

Phil Jones

@pgjones

Hmm, looks like aiomysql needs a lock or to use a connection pool?

Ah yea, aio-libs/aiomysql#179 points to https://github.com/aio-libs/aiomysql/blob/master/examples/example_pool.py

Jorge Escobar

@esfoobar

That's what I thought, but I tried returning a pool connection here: https://github.com/esfoobar/quart-feed/blob/master/db.py#L16-L24

However that conn2 object is different from the engine.acquire() here: https://github.com/esfoobar/quart-feed/blob/master/db.py#L14

Do you know of a snippet that has a pool that's compatible with SqlAlchemy?

Jorge Escobar

@esfoobar

I'm using SQLAlchemy Core so that pool implementation doesn't work

Tigran Tch

@NargiT

The ASGI root_path should work for this, could you try with hypercorn and see if it narrows down the bug to uvicorn or Quart?

root_path does not add in the url the path. Do I have to setup a proxy and rewrite url in order to redirect to "/" ?

Phil Jones

@pgjones

This may be a bug, I'll try find some time to investigate

@esfoobar have you tried using Databases?

Jorge Escobar

@esfoobar

I have read about it -- I can try implementing -- I just wish I knew it was going to fix the issue

But I appreciate your help @pgjones

Phil Jones

@pgjones

I use it, and it seems to setup connection pools

Jorge Escobar

@esfoobar

Awesome, I'll see if I can hook it up quickly and will let you know

Phil Jones

@pgjones

@NargiT I think ASGI servers have a bug, django/asgiref#229

Jorge Escobar

@esfoobar

@pgjones I'm SO HAPPY! The move to databases made all the difference. It's now rock solid, reloading as fast I can throws no errors!

And the SSE experience feels near-instantaneous, thanks!

Phil Jones

@pgjones

:+1:

Nice

Phil Jones

@pgjones

@NargiT The Hypercorn master branch should work as you expect with the root-path if you can try it out

pgjones/hypercorn@c9dd670

Jorge Escobar

@esfoobar

Hi @pgjones , I am now seeing a new error on tests that I hadn't seen before.

In my conftest I have the following fixture:

@pytest.fixture(scope="module")
async def create_test_app(create_db):
    app = create_app(**create_db)
    await app.startup()
    yield app
    await app.shutdown()

It seems app.shutdown() is throwing this error:

/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/six.py:703:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/six.py:703: in reraise
    raise value
/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/six.py:703: in reraise
    raise value
/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/pytest_asyncio/plugin.py:93: in finalizer
    loop.run_until_complete(async_finalizer())
/usr/local/lib/python3.8/asyncio/base_events.py:616: in run_until_complete
    return future.result()
/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/pytest_asyncio/plugin.py:85: in async_finalizer
    await gen_obj.__anext__()
conftest.py:67: in create_test_app
    await app.shutdown()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <quart.app.Quart object at 0x7f9947998dc0>

    async def shutdown(self) -> None:
        for func in self.after_serving_funcs:
            await func()
        app_ctx = _app_ctx_stack.top
>       await app_ctx.pop(None)

/root/.local/share/virtualenvs/quartfeed_app-1k77iZGH/lib/python3.8/site-packages/quart/app.py:2155: AttributeError
================================================================ short test summary info =================================================================
ERROR relationship/test_relationship.py::test_succesful_follow - AttributeError: 'NoneType' object has no attribute 'pop'
ERROR user/test_user.py::test_profile_edit - AttributeError: 'NoneType' object has no attribute 'pop'

Any ideas what is going on?

I'm using:

pytest = "==6.2.1"
pytest-asyncio = "==0.14.0"

On the application.py I have these:

    @app.before_serving
    async def create_db_conn():
        database = await db_connection()
        await database.connect()
        app.dbc = database

    @app.after_serving
    async def close_db_conn():
        await app.dbc.disconnect()

Phil Jones

@pgjones

It should work again if you use master, or if you utilise the test_app

Jorge Escobar

@esfoobar

That worked, but now I have an issue with context?

I have on the tests:

    # check that the user was created on the database itself
    async with create_test_app.app_context():

and I'm getting:

E       AttributeError: 'TestApp' object has no attribute 'app_context'

Phil Jones

@pgjones

You can still yield the app, just within the test_app context,

@pytest.fixture(scope="module")
async def create_test_app(create_db):
    app = create_app(**create_db)
    async with app.test_app():
        yield app

Jorge Escobar

@esfoobar

Amazing, that worked! Thanks!

TheHolyRoger

@TheHolyRoger

@pgjones forgive my vagueness because I'm reporting an issue I had a while back now - I was trying to run quart in a separate thread but would always get the "signal only works in main thread" error - I think it's something to do with the autoloader, which I did disable without any success?

Phil Jones

@pgjones

It is the usage of the shutdown_trigger that I think is the issue for you. This is set by default to be a signal (Ctrl-C), but as noted this is only works if Quart is run on the main thread. Instead you can specify your own shutdown_trigger and use the run_task method. The shutdown_trigger should be an awaitable that is done when you want the app to shutdown.

sferdi0

@sferdi0

I've noticed that CTRL-C'ing hypercorn takes a second or two to quit, possibly related to some cleanup process... Can I somehow replace this with a SIGKILL, in favor of quickly being able to start/stop hypercorn?

(For development purposes)

sferdi0

@sferdi0

await asyncio.sleep(config.graceful_timeout)

I FOUND YOU

sferdi0

@sferdi0

Any side-effects with setting this to 0?

Phil Jones

@pgjones

None

This is on my todo list to improve, I need to somehow early exit if the relevant tasks have completed.

McSinyx

@McSinyx:matrix.org

[m]

in case hypercorn runs on trio, does nursery/cancel scope makes it any easier?

Phil Jones

@pgjones

Hopefully, although I haven't got it right so far

Vito De Tullio

@ZeeD

Hi.
I've just updated quart, quart-trio and hypercorn and I'm having this mypy error:

: error: Argument 1 to "serve" has incompatible type "QuartTrio"; expected "Union[Type[ASGI2Protocol], Callable[[Union[HTTPScope, WebsocketScope, LifespanScope], Callable[[], Awaitable[Union[HTTPRequestEvent, HTTPDisconnectEvent, WebsocketConnectEvent, WebsocketReceiveEvent, WebsocketDisconnectEvent, LifespanStartupEvent, LifespanShutdownEvent]]], Callable[[Union[HTTPResponseStartEvent, HTTPResponseBodyEvent, HTTPServerPushEvent, HTTPDisconnectEvent, WebsocketAcceptEvent, WebsocketSendEvent, WebsocketResponseStartEvent, WebsocketResponseBodyEvent, WebsocketCloseEvent, LifespanStartupCompleteEvent, LifespanStartupFailedEvent, LifespanShutdownCompleteEvent, LifespanShutdownFailedEvent]], Awaitable[None]]], Awaitable[None]]]"
moves\web\__init__.py:85: error: Argument 1 to "serve" has incompatible type "QuartTrio"; expected "Union[Type[ASGI2Protocol], Callable[[Union[HTTPScope, WebsocketScope, LifespanScope], Callable[[], Awaitable[Union[HTTPRequestEvent, HTTPDisconnectEvent, WebsocketConnectEvent, WebsocketReceiveEvent, WebsocketDisconnectEvent, LifespanStartupEvent, LifespanShutdownEvent]]], Callable[[Union[HTTPResponseStartEvent, HTTPResponseBodyEvent, HTTPServerPushEvent, HTTPDisconnectEvent, WebsocketAcceptEvent, WebsocketSendEvent, WebsocketResponseStartEvent, WebsocketResponseBodyEvent, WebsocketCloseEvent, LifespanStartupCompleteEvent, LifespanStartupFailedEvent, LifespanShutdownCompleteEvent, LifespanShutdownFailedEvent]], Awaitable[None]]], Awaitable[None]]]"

the "incriminated" line is await hypercorn.trio.serve(app, config), where I have

app = cast(quart_trio.QuartTrio,
               quart_cors.cors(quart_trio.QuartTrio(__name__),
                               allow_origin='*',
                               allow_methods=['POST'],
                               allow_headers=['content-type']))

Phil Jones

@pgjones

Best to ignore this at the moment, will be fixed in an upcoming release

1 reply

TheHolyRoger

@TheHolyRoger

It is the usage of the shutdown_trigger that I think is the issue for you. This is set by default to be a signal (Ctrl-C), but as noted this is only works if Quart is run on the main thread. Instead you can specify your own shutdown_trigger and use the run_task method. The shutdown_trigger should be an awaitable that is done when you want the app to shutdown.

Thanks!

paulinechane

@PaulineChane

It is the usage of the shutdown_trigger that I think is the issue for you. This is set by default to be a signal (Ctrl-C), but as noted this is only works if Quart is run on the main thread. Instead you can specify your own shutdown_trigger and use the run_task method. The shutdown_trigger should be an awaitable that is done when you want the app to shutdown.

Thanks!

hello! apologies for poorly phrased questions in advance, i am very new to python frameworks and asyncio!

i am still having a hard time to get this to work -- trying to run a quart app to be used on a website along with bot that runs 24/7 on discord. my understanding is that this run_task() method would be run for the quart app?

Baran Yildirim

@baranyildirim

Is it possible to make Quart work with React via templates? I would like to have a quart application where I use React components, but I do not want a single page application. I also don't want to run node and quart simultaneously.

Phil Jones

@pgjones

Yes, you can just embed React as you need into the templates (via a script tag).

I typically build a SPA and serve that with Quart

Ernesto Ruge

@the-infinity

I usually use React + Quart or Fask partly jinja2-rendered, partly React-rendered. It works really fine (but Quart / Flask has not much to do with the React part, it just feeds it via API).

It even works as a single page application including deeplinks and React Router if you set your endpoints in a correct way

Phil Jones

@pgjones

@PaulineChane I'll try and write something up for this soon - short of time.
Yes though, the run_task method would run the quart app.

TheHolyRoger

@TheHolyRoger

hey @pgjones do you have plans to add "call_on_close" similar to flask to quart?

https://stackoverflow.com/questions/48994440/execute-a-function-after-flask-returns-response

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