async-python-patterns

# Async Python Patterns Comprehensive guidance for implementing asynchronous Python applications using asyncio, concurrent programming patterns, and async/await for building high-performance, non-blocking systems. ## When to Use This Skill - Building async web APIs (FastAPI, aiohttp, Sanic) - Implementing concurrent I/O operations (database, file, network) - Creating web scrapers with concurrent requests - Developing real-time applications (WebSocket servers, chat systems) - Processing multiple independent tasks simultaneously - Building microservices with async communication - Optimizing I/O-bound workloads - Implementing async background tasks and queues ## Sync vs Async Decision Guide Before adopting async, consider whether it's the right choice for your use case. | Use Case | Recommended Approach | |----------|---------------------| | Many concurrent network/DB calls | `asyncio` | | CPU-bound computation | `multiprocessing` or thread pool | | Mixed I/O + CPU | Offload CPU work with `asyncio.to_thread()` | | Simple scripts, few connections | Sync (simpler, easier to debug) | | Web APIs with high concurrency | Async frameworks (FastAPI, aiohttp) | **Key Rule:** Stay fully sync or fully async within a call path. Mixing creates hidden blocking and complexity. ## Core Concepts ### 1. Event Loop The event loop is the heart of asyncio, managing and scheduling asynchronous tasks. **Key characteristics:** - Single-threaded cooperative multitasking - Schedules coroutine...