Why is Uvicorn advised to run through gunicorn?

Question

Python

Hey!

Does anyone know why the Uvicorn documentation advises running an ASGI application through gunicorn using uvicorn workers? Is this purely due to process management or is uvicorn not considered reliable for live environments...? And if the application is launched inside a docker container (by means of docker-compose) - do you need process management from gunicorn at all if docker-compose does this? Maybe in this case it's worth running uvicorn directly? Thank you!

Answer 1

Because uvicorn is not a process manager. It launches exactly one process, in which there will be one event loop, which will spin everything on one core. If you have a 4-core CPU on the server, then you need to run at least 4 such uvicorns to fully utilize the resources. That's what gunicorn is for.

Answer 2

Uvicorn runs in multiple threads ( config.workers )

server = Server(Config)
if server.config.workers > 1:
  app = Multiprocess(server.config, target=server.run, sockets=[server.config.bind_socket()]).run
else:
  app = server.run

app()