如何抑制来自 aiohttp 的这些虚假警告？

Question

I've got some code that makes requests to remote sites using asyncio and aiohttp .

import aiohttp, asyncio

async def f():
    session = aiohttp.ClientSession()
    async with session.get('https://httpbin.org/get') as response:
        pass

asyncio.run(f())

When I run it, it produces

Unclosed client session
client_session: <aiohttp.client.ClientSession object at 0x7f56796b3d68>
Unclosed connector
connections: ['[(<aiohttp.client_proto.ResponseHandler object at 0x7f56793836a8>, 0.0)]']
connector: <aiohttp.connector.TCPConnector object at 0x7f56796b3f98>

Now, the way I make requests is not recommended (for various reasons), which is why I'm getting those messages. However, they sure won't stop me, and so I just wish to never see them again.

I reasonably assumed that they are normal warnings and tried disabling them via the -Wignore command line option, as well as by putting the following code at the start of the script

import warnings
warnings.filterwarnings('ignore')

but the messages kept appearing. How come? How can I suppress them?

Answer 1

Turns out, aiohttp not only emits normal warnings with that text, but also calls the exception handler of the loop with the same message during the unexceptional __del__ invocation.

Source for ClientSession :

def __del__(self, _warnings: Any=warnings) -> None:
    if self._protocol is not None:
        ...
        _warnings.warn('Unclosed connection {!r}'.format(self),
                       ResourceWarning,
                       **kwargs)
        ...
        context = {'client_connection': self,
                   'message': 'Unclosed connection'}
        ...
        self._loop.call_exception_handler(context) # <---

Thus, if you only want to suppress the warnings that come from the aiohttp library and through the loop's exception handler, you have to either

Replace the loop's default exception handler

For example, with a no-op function:

async def f():
    asyncio.get_running_loop().set_exception_handler(lambda loop, context: None)
    ...

# No output

or

Change the logging level for the whole asyncio module

Because the loop's default exception handler logs the exception messages with the logging.ERROR level, you will have to set the level to logging.CRITICAL

import logging

async def f():
    logging.getLogger('asyncio').setLevel(logging.CRITICAL)
    ...

# No output