async-python-patternslisted

# 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. ## 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 coroutines for execution - Handles I/O operations without blocking - Manages callbacks and futures ### 2. Coroutines Functions defined with `async def` that can be paused and resumed. **Syntax:** ```python async def my_coroutine(): result = await some_async_operation() return result ``` ### 3. Tasks Scheduled coroutines that run concurrently on the event loop. ### 4. Futures Low-level objects representing eventual results of async operations.