Starlette and Socketio Improvements
I've made some improvements, especially to handle SIGINT (
c) properly. Additionally, I wanted to start background processes without waiting for a client to connect (this is a solution I saw online).
The core problem was that all async tasks should be on the same loop. The solution took some digging around uvicorn internals, but the following worked:
- Get the Uvicorn server as an awaitable;
- Join the awaitable with your background tasks and return when the first completes
- Run the composed application.
This properly responds to SIGINT and all processes start without waiting for outside interaction.
Background tasks are more like workers here. One-off tasks fall in two categories:
- Startup or shutdown: Use Starlette hooks for startup and shutdown to handle work there;
- Based on interactions from outside: Just call tasks when an API is called.
from app import app
from uvicorn.loops.uvloop import uvloop_setup
format="%(asctime)-15s %(levelname)-8s %(message)s"
""" Returns running the app in uvicorn as an awaitable to join the main
asyncio loop. """
config = uvicorn.Config(app, host='0.0.0.0', port=8000)
server = uvicorn.Server(config)
async def main(app):
""" Joins unicorn together with background tasks defined in the app. """
# Make the list with awaitables
aws = [uvicorn_task(),
# Run and return when the first completes or is cancelled
await asyncio.wait(aws, return_when=asyncio.FIRST_COMPLETED)
if __name__ == '__main__':
# Set up the loop
loop = asyncio.get_event_loop()
# Run the main loop