channels: Using uvicorn + gunicorn as ASGI server fails to boot

With latest update of twisted 21.2.0 the app stops to inicialize when using gunicorn + uvicorn as ASGI server.

• Your OS and runtime environment, and browser if applicable Using docker image python:3.9.2-slim-buster

• A pip freeze output showing your package versions

aioredis==1.3.1
appnope==0.1.2
asgiref==3.3.1
async-timeout==3.0.1
attrs==20.3.0
autobahn==21.2.2
Automat==20.2.0
backcall==0.2.0
cffi==1.14.5
channels==3.0.3
channels-redis==3.2.0
click==7.1.2
constantly==15.1.0
coverage==5.4
cryptography==3.4.6
daphne==3.0.1
decorator==4.4.2
Django==3.1.7
django-cors-headers==3.7.0
django-redis==4.12.1
djangorestframework==3.12.2
drf-extensions==0.7.0
factory-boy==3.2.0
Faker==6.5.0
freezegun==1.1.0
gunicorn==20.0.4
h11==0.12.0
hiredis==1.1.0
httptools==0.1.1
hyperlink==21.0.0
idna==3.1
incremental==17.5.0
iniconfig==1.1.1
ipdb==0.13.4
ipython==7.21.0
ipython-genutils==0.2.0
jedi==0.18.0
msgpack==1.0.2
munch==2.5.0
packaging==20.9
parso==0.8.1
pexpect==4.8.0
pickleshare==0.7.5
pluggy==0.13.1
prompt-toolkit==3.0.16
psycopg2==2.8.6
ptyprocess==0.7.0
py==1.10.0
pyasn1==0.4.8
pyasn1-modules==0.2.8
pycparser==2.20
Pygments==2.8.0
pyOpenSSL==20.0.1
pyparsing==2.4.7
pytest==6.2.2
pytest-cov==2.11.1
pytest-django==4.1.0
pytest-freezegun==0.4.2
python-dateutil==2.8.1
python-dotenv==0.15.0
pytz==2021.1
PyYAML==5.4.1
redis==3.5.3
service-identity==18.1.0
six==1.15.0
sqlparse==0.4.1
text-unidecode==1.3
toml==0.10.2
traitlets==5.0.5
Twisted==21.2.0
txaio==21.2.1
uvicorn==0.13.4
uvloop==0.15.2
watchgod==0.7
wcwidth==0.2.5
websockets==8.1
zope.interface==5.2.0

• What you expected to happen vs. what actually happened I expect to server boot up.

• How you’re running Channels (runserver? daphne/runworker? Nginx/Apache in front?) gunicorn -w 4 -b 0.0.0.0:8000 -k uvicorn.workers.UvicornWorker asgi:application

• Console logs and full tracebacks of any errors

[2021-03-01 12:48:40 +0000] [7] [INFO] Worker exiting (pid: 7)
[2021-03-01 12:48:40 +0000] [7] [ERROR] Exception in worker process
Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/gunicorn/arbiter.py", line 583, in spawn_worker
worker.init_process()
File "/usr/local/lib/python3.9/site-packages/uvicorn/workers.py", line 63, in init_process
super(UvicornWorker, self).init_process()
File "/usr/local/lib/python3.9/site-packages/gunicorn/workers/base.py", line 119, in init_process
self.load_wsgi()
File "/usr/local/lib/python3.9/site-packages/gunicorn/workers/base.py", line 144, in load_wsgi
self.wsgi = self.app.wsgi()
File "/usr/local/lib/python3.9/site-packages/gunicorn/app/base.py", line 67, in wsgi
self.callable = self.load()
File "/usr/local/lib/python3.9/site-packages/gunicorn/app/wsgiapp.py", line 49, in load
return self.load_wsgiapp()
File "/usr/local/lib/python3.9/site-packages/gunicorn/app/wsgiapp.py", line 39, in load_wsgiapp
return util.import_app(self.app_uri)
File "/usr/local/lib/python3.9/site-packages/gunicorn/util.py", line 358, in import_app
mod = importlib.import_module(module)
File "/usr/local/lib/python3.9/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 790, in exec_module
File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
File "/app/asgi.py", line 17, in <module>
django_asgi_application = get_asgi_application()
File "/usr/local/lib/python3.9/site-packages/django/core/asgi.py", line 12, in get_asgi_application
django.setup(set_prefix=False)
File "/usr/local/lib/python3.9/site-packages/django/__init__.py", line 24, in setup
apps.populate(settings.INSTALLED_APPS)
File "/usr/local/lib/python3.9/site-packages/ddtrace/contrib/trace_utils.py", line 48, in wrapper
return func(mod, pin, wrapped, instance, args, kwargs)
File "/usr/local/lib/python3.9/site-packages/ddtrace/contrib/django/patch.py", line 166, in traced_populate
ret = func(*args, **kwargs)
File "/usr/local/lib/python3.9/site-packages/django/apps/registry.py", line 91, in populate
app_config = AppConfig.create(entry)
File "/usr/local/lib/python3.9/site-packages/django/apps/config.py", line 116, in create
mod = import_module(mod_path)
File "/usr/local/lib/python3.9/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 790, in exec_module
File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
File "/usr/local/lib/python3.9/site-packages/channels/apps.py", line 4, in <module>
import daphne.server
File "/usr/local/lib/python3.9/site-packages/daphne/server.py", line 20, in <module>
asyncioreactor.install(twisted_loop)
File "/usr/local/lib/python3.9/site-packages/twisted/internet/asyncioreactor.py", line 307, in install
reactor = AsyncioSelectorReactor(eventloop)
File "/usr/local/lib/python3.9/site-packages/twisted/internet/asyncioreactor.py", line 60, in __init__
raise TypeError(
TypeError: SelectorEventLoop required, instead got: <uvloop.Loop running=False closed=False debug=False>