Overview

Uvicorn 0.19, released on October 19, 2022, adds official Python 3.11 support and improves ASGI lifespan handling.

Main Features

Python 3.11 support

Python 3.11 is officially supported, with significant performance gains from CPython optimizations.

python 
# Python 3.11 brings ~25% performance gain
import uvicorn

uvicorn.run(
    'app:app',
    host='0.0.0.0',
    port=8000,
    loop='asyncio',  # optimized asyncio loop in 3.11
)

ASGI lifespan

ASGI lifespan event handling is improved with better error propagation on startup and shutdown.

python 
from contextlib import asynccontextmanager
from starlette.applications import Starlette

@asynccontextmanager
async def lifespan(app):
    print('Starting...')
    yield
    print('Shutting down...')

app = Starlette(lifespan=lifespan)

Sources