Asyncio

This is your reference for Python's async/await concurrency model, covering everything from basic coroutines to production patterns with aiohttp and FastAPI. You get practical examples of asyncio.gather() for parallel tasks, proper error handling with return_exceptions, and the often misunderstood event loop mechanics. The blocking I/O section with run_in_executor is especially useful since mixing sync and async code trips up most people. It includes the primitives you actually need like locks and queues, plus real world patterns for async HTTP clients, database connections, and WebSocket handling. The code examples are complete and runnable, not fragments. Honestly, this covers about 90% of what you'll encounter in async Python work, and the progressive disclosure summary is a solid quick reference when you forget the syntax.