async-python-patterns_skill

Overview

This skill teaches practical patterns for building asynchronous Python applications with asyncio, async/await, and concurrent programming primitives. It focuses on non-blocking I/O, task management, synchronization, and real-world integrations like HTTP clients, databases, and WebSocket servers. Expect clear, copy-pasteable patterns that scale from simple scripts to production services.

How this skill works

The skill inspects common async building blocks: event loop behavior, coroutines, tasks, futures, and synchronization primitives (locks, semaphores, queues). It shows how to compose these primitives with patterns such as gather(), create_task(), producer-consumer queues, timeouts, async context managers, and async iterators. Examples demonstrate error handling, rate limiting, safe resource cleanup, and integrating async HTTP clients and databases.

When to use it

• Building async web APIs (FastAPI, aiohttp, Sanic)
• Running many concurrent I/O-bound operations (HTTP, DB, files)
• Implementing real-time systems (WebSocket servers, chat, notifications)
• Creating web scrapers with concurrent requests
• Coordinating background workers, queues, or microservice communication

Best practices

• Prefer asyncio.run() for top-level program entry and avoid mixing multiple event loops
• Use asyncio.create_task() for background work and keep strong references to tasks you need to await or cancel
• Use asyncio.gather(..., return_exceptions=True) or explicit try/except to surface and handle task failures
• Apply semaphores or connection pools to enforce rate limits and prevent resource exhaustion
• Always use async context managers for resources (sessions, connections) to ensure deterministic cleanup

Example use cases

• Concurrent HTTP scraping with aiohttp and rate limiting via Semaphore
• Fetching users, orders, and profiles concurrently from an async DB client using gather()
• Background task processing with producer-consumer queues for workers and graceful shutdown
• Implementing WebSocket broadcast servers that send messages concurrently to many clients
• Using async iterators to stream paginated API results without blocking the event loop