asyncio timeouts & cancellation

Always bound network calls with a timeout. Modern asyncio.timeout() (3.11+) is the cleanest way; on older Pythons use asyncio.wait_for.

import asyncio

async def slow():
    try:
        await asyncio.sleep(10)
    except asyncio.CancelledError:
        # cleanup: close sockets, release resources, then re-raise
        print("cancelled, cleaning up")
        raise

async def main():
    try:
        async with asyncio.timeout(0.05):   # 50 ms budget
            await slow()
    except TimeoutError:
        print("timed out")

await main()

**Patterns**

• asyncio.wait_for(coro, timeout=...) — same idea, returns the result.
• task.cancel() raises CancelledError inside the coroutine. Re-raise after cleanup.
• asyncio.shield(coro) — protect a critical section from outer cancellation.
• asyncio.TaskGroup (3.11+) — structured concurrency; cancels siblings on failure.