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I have the following code which I'm trying to run to get data from an api asynchronously, using asyncio and aiohttp:

import asyncio
import aiohttp

api = "...some api..."
apps = [
    ...list of api parameters...
]

def getTasks(sess):
    tasks = list()
    for app in apps:
        tasks.append(asyncio.create_task(sess.get(api+app, ssl = False)))
    return tasks

async def main():
    results = list()
    async with aiohttp.ClientSession() as atpSession:
        tasks = getTasks(atpSession)
        responses = await asyncio.gather(*tasks)
        for response in responses:
            results.append(await response.json())
    print(results[-1])
    print("Done!")

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

Though I'm getting the response data, but the following error keeps popping up:

Exception ignored in: <function _ProactorBasePipeTransport.__del__ at 0x000001C5D98F7490>
Traceback (most recent call last):
  File "C:\Program Files\Python310\lib\asyncio\proactor_events.py", line 116, in __del__
    self.close()
  File "C:\Program Files\Python310\lib\asyncio\proactor_events.py", line 108, in close
    self._loop.call_soon(self._call_connection_lost, None)
  File "C:\Program Files\Python310\lib\asyncio\base_events.py", line 750, in call_soon
    self._check_closed()
  File "C:\Program Files\Python310\lib\asyncio\base_events.py", line 515, in _check_closed
    raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed

And there are multiple such similar tracebacks shown one by one.

Now another way I tried this was by removing asyncio.run(main()) and just using some different lines of code:

import asyncio
import aiohttp

api = "...some api..."
apps = [
    ...list of api parameters...
]

def getTasks(sess):
    tasks = list()
    for app in apps:
        tasks.append(asyncio.create_task(sess.get(api+app, ssl = False)))
    return tasks

async def main():
    results = list()
    async with aiohttp.ClientSession() as atpSession:
        tasks = getTasks(atpSession)
        responses = await asyncio.gather(*tasks)
        for response in responses:
            results.append(await response.json())
    print(results[-1])
    print("Done!")

if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

Using the following did not give me the prior error but gave me:

DeprecationWarning: There is no current event loop
  loop = aio.get_event_loop()

Although, it did give me the responses, my question is, why are these differences arising? Being an absolute beginner with asyncio, I had read that as application developers, we should be using the high level apis like asyncio.run() instead of the low level apis, so why is asyncio.run() creating such problems?

Biswadeep Sarkar
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  • Can you please post a [Minimal Reproducible Example](https://stackoverflow.com/help/minimal-reproducible-example) and an exact error traceback? – matszwecja Feb 21 '23 at 15:56
  • To add to the above, where and how are you running your code? There are known Jupyter Notebook versions where the asyncio loop is opened & closed before user code execution. – felipe Feb 22 '23 at 08:42
  • I've edited and put the entire code and traceback there. Nothing more to it, that's just all. – Biswadeep Sarkar Feb 22 '23 at 13:06
  • And also, I'm not using jupyter notebook, I'm plainly using the vscode editor and the git bash terminal – Biswadeep Sarkar Feb 22 '23 at 13:10

1 Answers1

0

You don't need the asyncio.create_task() and this is likely the cause of the error. Take a look at this answer for a working example of AsyncIO + AIOHTTP.

Louis Lac
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  • 1
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  • Tried to run the code in the answer that you mentioned. Still getting the same traceback as I mentioned in my question: RuntimeError: Event loop is closed. – Biswadeep Sarkar Feb 23 '23 at 09:15
  • Works fine on my side, what Python version are you using? How do you launch the program? What is your OS? – Louis Lac Feb 23 '23 at 11:04
  • Python 3.10.5 running the program through the gitbash terminal OS is windows – Biswadeep Sarkar Feb 23 '23 at 11:21
  • Weird. Try running the code in an isolated Python environment (with pyenv, venv or conda for instance). Also try with another version of Python. – Louis Lac Feb 23 '23 at 17:18