Why asyncio loop cant stop?

Question

I have a piece of code like this:

import asyncio import aiohttp from time import process_time ts = process_time() asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy()) async def bot(s): async with s.get('https://httpbin.org/uuid') as r: resp = await r.json() print(resp['uuid'][0]) if resp['uuid'][0] == '0': print("EUREEKA") return async def main(): async with aiohttp.ClientSession() as s: await asyncio.gather(*[bot(s) for _ in range(0, 1000)]) if __name__ == "__main__": asyncio.run(main()) te = process_time() print(te-ts)

I want to stop the loop process when "EUREEKA" appears. I use return but it doesn't stop either. What is the correct way to stop it? result of code

It stops, but you're creating multiple tasks, not just one. — Łukasz Kwieciński
– Łukasz Kwieciński, Commented May 30, 2021 at 9:15

user4815162342 · Accepted Answer · 2021-05-30 18:47:24Z

asyncio.gather will wait for all tasks to complete. If you want to stop on first task that reaches the finish line, you can use asyncio.wait with FIRST_COMPLETED:

async def main(): async with aiohttp.ClientSession() as s: done, pending = await asyncio.wait( [bot(s) for _ in range(0, 1000)], return_when=asyncio.FIRST_COMPLETED ) # ensure we notice if the task that is done has actually raised for t in done: await t # cancel the tasks that haven't finished, so they exit cleanly for t in pending: t.cancel()

@AlfianAP In both loops t holds instances of asyncio.Task, itself a subclass of asyncio.Future.

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