aiohttp - How to save a persistent session in class namespace - python-3.7

Question

I am trying to use aiohttp in one of my projects and struggling to figure out how to create a persistent aiohttp.ClientSession object. I have gone through the official aiohttp documentation but did not find it help in this context.
I have looked through other online forums and noticed that a lot has changed ever since aiohttp was created. In some examples on github, the aiohttp author is shown to be creating a ClientSession outside a coroutine functions (i.e. class Session: def __init__(self): self.session = aiohttp.ClientSession()). I also found that one should not create a ClientSession outside coroutine.
I have tried the following:
class Session:
def __init__(self):
self._session = None
async def create_session(self):
self._session = aiohttp.ClientSession()
async fetch(self, url):
if self._session is None:
await self.create_session()
async with self._session.get(url) as resp:
return await resp.text()
I am getting a lot of warning about UnclosedSession and connector. I also frequently get SSLError. I also noticed that 2 out of three calls gets hung and I have to CTRL+C to kill it.
With requests I can simply initialize the session object in __init__, but it's not as simple as this with aiohttp.
I do not see any issues if I use the following (which is what I see as example all over the place) but unfortunately here I end up creating ClientSession with every request.
def fetch(url):
async with aiohttp.ClientSession() as session:
async with session.get(url) as resp:
return await resp.text()
I can wrap aiohttp.ClientSession() in another function and use that as context-manager, but then too I would end up creating a new session object every time I call the wrapper function. I am trying to figure how to save a aiohttp.ClientSession in class namespace and reuse it.
Any help would be greatly appreciated.

Answer 1

Here is working example:
from aiohttp import ClientSession, TCPConnector
import asyncio
class CS:
_cs: ClientSession
def __init__(self):
self._cs = ClientSession(connector=TCPConnector(verify_ssl=False))
async def get(self, url):
async with self._cs.get(url) as resp:
return await resp.text()
async def close(self):
await self._cs.close()
async def func():
cs = CS()
print(await cs.get('https://google.com'))
await cs.close() # you must close session
loop = asyncio.get_event_loop()
loop.run_until_complete(func())

Answer 2

You can do it.
I implemented a way to share session when writing Django programs (using asgi).Use pid to mark the session of different processes, which is convenient for django to call between different processes.
After actual testing, I can directly call the shared session.
Django 3.2
uvicorn
aiohttp.py
import os
import asyncio
import aiohttp
import logging
session_list = {}
logger = logging.getLogger(__name__)
class Req:
#property
def set_session(self):
try:
loop = asyncio.get_running_loop()
except:
loop = asyncio.get_event_loop()
asyncio.set_event_loop(loop)
session = aiohttp.ClientSession(loop=loop)
session_list.update({os.getpid(): session})
return session
def __init__(self):
if session_list.get(os.getpid()):
self.session = session_list.get(os.getpid())
else:
self.session = self.set_session
async def test(self):
if session_list:
session = session_list.get(os.getpid())
if session and session.closed:
session_list.pop(os.getpid())
session = self.set_session
else:
session = self.set_session
if not session or session.loop.is_running():
session = self.set_session
logger.warning("session abnormal")
result = await session.get("http://httpbing.org/get")
print(result.status)
req = Req()
views.py
from django.http import HttpResponse
from django.shortcuts import render # noqa
from django.views.generic import View
from django.utils.decorators import classonlymethod
import asyncio
class TTT(View):
#classonlymethod
def as_view(cls, **initkwargs):
view = super().as_view(**initkwargs)
view._is_coroutine = asyncio.coroutines._is_coroutine
return view
async def get(self, request):
await req.test()
return HttpResponse("ok")