CODEWITHSUNDEEP
pythonpython-3.xpython-asyncioaiohttp
brillenheini
brillenheini

Reputation: 963

RuntimeError: Event loop is closed (and I don't know why)

I know, this has been asked maybe a hundred times, but I still cannot figure out why this always draws an error at the end.

import asyncio
import aiohttp

async def read_index_page():
    async with aiohttp.ClientSession() as session:
        async with session.get('https://some/api/url') as resp:
            print(resp.status)

async def main():
    loop = asyncio.get_event_loop()

    task = loop.create_task(read_index_page())

    await asyncio.gather(task)

if __name__ == '__main__':
    asyncio.run(main())

This reports the well known runtime error for the event look is closed. I run this code on a Windows 10 machine.

From my point of view I do things right but I'm a totally beginner in using asyncio. So, please be gentle. :)

Regards, Thomas

Upvotes: 1

Views: 3430

Answers (1)

Artiom Kozyrev
Artiom Kozyrev

Reputation: 3836

Try to set another loop implementation for your app, on the other hand I should say that I have no error on my Windows 10 Home, tested on Python 3.6 (with Aiohttp 3.4.4) and Python 3.9. (with Aiohttp 3.7.4.post())

import asyncio
from aiohttp import ClientSession

URL = "http://..."


async def send_req(session: ClientSession):
    async with session.get(URL) as resp:
        if resp.status == 200:
            r = await resp.json()
            print(r)
        else:
            print(resp.status)


async def main():
    # check what loop is really running in our Main Thread now
    loop = asyncio.get_running_loop()
    print(loop)
    # no need to create ClientSession for all send_req, you need only one ClientSession
    async with ClientSession() as session:
        # asyncio gather creates tasks itself, no need to create tasks outside
        await asyncio.gather(*[send_req(session) for _ in range(8)])

if __name__ == '__main__':
    # set another loop implementation:
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
    asyncio.run(main())

Upvotes: 2

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