Closing aiohttp.ClientSession on parent object destruction

Question

I'm writing a CLI for accessing REST API. I have defined aiohttp.ClientSession class field _client_session in async init method.

How do I close the aiohttp.ClientSession properly? If I do:

import asyncio
import aiohttp


class Profile:                                                                    
    def __init__(self, loop):                                                     
        self._loop = loop                                                         
        self._client_session = None                                               

    def __del__(self):                                                            
        self._loop.run_until_complete(self._client_session.close())              

    async def async_init(self):
        self._client_session = aiohttp.ClientSession()                           

    @classmethod
    async def create(cls, loop):
        self = cls(loop)
        await self.async_init()
        return self


loop = asyncio.get_event_loop()
profile = loop.run_until_complete(Profile.create(loop))                          
loop.close()

I get this:

Exception ignored in: <bound method Profile.__del__ of <profile.Profile object at 0x7f8ab82e15c0>>
Traceback (most recent call last):
File "/home/rominf/projects/profile/profile/__init__.py", line 197, in __del__
File "/home/rominf/.pyenv/versions/3.6.6/lib/python3.6/asyncio/base_events.py", line 444, in run_until_complete
File "/home/rominf/.pyenv/versions/3.6.6/lib/python3.6/asyncio/base_events.py", line 358, in _check_closed
RuntimeError: Event loop is closed
sys:1: RuntimeWarning: coroutine 'ClientSession.close' was never awaited
Unclosed client session
client_session: <aiohttp.client.ClientSession object at 0x7f8ab43bf588>
Unclosed connector
connections: ['[(<aiohttp.client_proto.ResponseHandler object at 0x7f8ab28a06a8>, 11519.944147989)]']
connector: <aiohttp.connector.TCPConnector object at 0x7f8ab43bf3c8>

I understand this happens for a reason: I close the loop before garbage collector deletes profile. The solution is to delete it manually with del, but I don't want to do this.

It there a way to register the future for execution just before event loop closing?

Answer 1

asyncio doesn't support IO in destructors. The same for constructors and properties.

The recommended way is adding async with Profile or await profile.close() support.