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Changing state of started or joined application is deprecated....grrrr #1947

samuelcolvin opened this issue Jun 2, 2017 · 6 comments


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@samuelcolvin samuelcolvin commented Jun 2, 2017

Long story short

I very often want to set items on "frozen" app. I'm getting depreciation warnings for this and in future (presumably) this will fail outright. This is very frustrating.

This is made worse by pytest 3.1 which prints all warnings making this harder to ignore.

Expected behaviour

app['database'] = await create_my_database(...)

In a startup function should not cause deprecation warnings.

Actual behaviour

I'm getting warnings in lots of setups which I would have thought sensible.


in unit tests setting up a secondary server:

def mock_external_server(loop, test_server):
    app = Application()
    app.router.add_post('/whatever.json', handler)
    server = loop.run_until_complete(test_server(app))
    app['server_name'] = f'http://localhost:{server.port}'
    return server

This causes a warning because I'm setting the server_name item on an app which is started.

using startup function:

async def startup(app: web.Application):
    app['pg_engine'] = await create_engine(pg_dsn(app['database']), loop=app.loop)


app = web.Application()

(real life example here)

This again causes warnings setting pg_engine in a startup script.


Surely this warning is wrong? If not what workaround should I use?

The only solution I can think of is an ugly bodge:

async def startup(app: web.Application):
    app['data']['pg_engine'] = await create_engine(pg_dsn(app['database']), loop=app.loop)


app = web.Application(middlewares=middleware)
app['data'] = {}
@samuelcolvin samuelcolvin added the server label Jun 2, 2017
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@asvetlov asvetlov commented Jun 3, 2017

Initial intention for 'freezing' was prevention on route table modification after initialization phase.
After that I've though that freezing global state after on_startup is also good idea.

As I see in code for run_app this sequence is supported: .freeze() is called on first server socket creation, all on_startup signals are finished at this time.

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@samuelcolvin samuelcolvin commented Jun 3, 2017

import pytest
from aiohttp import web

async def startup(app):
    app['foobar'] = 123

async def handle(request):
    return web.Response(text='hello')

def create_app():
    app = web.Application()
    app.router.add_get('/', handle)
    return app

def cli(loop, test_client):
    app = create_app()
    return loop.run_until_complete(test_client(app))

async def test_hello(cli):
    resp = await cli.get('/')
    assert resp.status == 200
    text = await resp.text()
    assert 'o' in text

Then run

pytest --pythonwarnings=error

gives: DeprecationWarning: Changing state of started or joined application is deprecated

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@asvetlov asvetlov commented Jun 14, 2017

The error was in aiohttp.test_utils. aiohttp.web.run_app was working as expected.
Fixed. Thanks for report.

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@asvetlov asvetlov commented Jun 14, 2017

Ooop, something is wrong with run_app too. I'll fix it.

@asvetlov asvetlov reopened this Jun 14, 2017
@asvetlov asvetlov closed this in 8f3d8f2 Jun 14, 2017
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@asvetlov asvetlov commented Jun 14, 2017

Finally fixed

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@lock lock bot commented Oct 28, 2019

This thread has been automatically locked since there has not been
any recent activity after it was closed. Please open a new issue for
related bugs.

If you feel like there's important points made in this discussion,
please include those exceprts into that new issue.

@lock lock bot added the outdated label Oct 28, 2019
@lock lock bot locked as resolved and limited conversation to collaborators Oct 28, 2019
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