Event Loop Starvation in CPU-Bound Python Workloads

A frequent architectural misconception when designing asynchronous Python services with FastAPI or aiohttp is assuming that declaring async endpoints guarantees non-blocking execution across all workloads.

While asyncio provides high-concurrency cooperative multitasking for I/O-bound operations (database sockets, external HTTP requests, and network streams), the event loop executes on a single OS thread . Whenever an async coroutine invokes synchronous CPU-bound operations—such as deserializing large payloads, executing local computer vision inference, or rendering binary reports—the event loop blocks entirely.…