Python Async: A Practical Guide

Use asyncio when you're I/O bound — HTTP calls, DB queries, file I/O. Don't reach for it for CPU-bound work; use multiprocessing or Rust extensions instead.

import asyncio, httpx

async def fetch(url):
    async with httpx.AsyncClient() as c:
        r = await c.get(url)
        return r.text

async def main():
    urls = [f"https://example.com/{i}" for i in range(50)]
    results = await asyncio.gather(*(fetch(u) for u in urls))
    print(len(results))

asyncio.run(main())