How does Uvicorn use asyncio to handle thousands of concurrent connections?
Tests async concurrency and the GIL. Great answers cover the event loop suspending coroutines at await, Uvicorn interleaving connections, and multi-process workers for parallelism. Red flag: claiming asyncio uses threads per request or bypasses the GIL.
This tests cooperative multitasking and the GIL. A strong answer describes the event loop as a single-threaded I/O multiplexer that suspends coroutines at await. It explains Uvicorn owns the loop, passes ASGI events to FastAPI, and interleaves thousands of connections during I/O waits. It also notes the GIL prevents multi-core execution in one process, so Uvicorn uses multiple workers for parallelism. Red flag: claiming asyncio spawns threads per connection or eliminates the GIL.
Read the original → fastapi.tiangolo.com
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- #asyncio
- #fastapi
- #uvicorn
- #concurrency
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