Async Python Patterns

If you're building anything with FastAPI, aiohttp, or need to handle concurrent I/O operations without blocking, this gives you structured guidance on asyncio patterns. It covers the practical stuff like task management, queues, timeouts, and backpressure handling, plus points you to a playbook with concrete examples. The scope is appropriately narrow: it's honest about when not to use async (CPU-bound work, simple scripts) and focuses on I/O-heavy scenarios like web scrapers, WebSocket servers, and microservices. Good guardrails around testing and error handling for async code, which is where things usually get messy.