等待多个aiohttp请求导致“会话已关闭”错误

我正在编写一个帮助类,用于以异步方式处理多个url请求。代码如下。

class urlAsyncClient(object):
    def  __init__(self, url_arr):
        self.url_arr = url_arr

    async def async_worker(self):
        result = await self.__run()
        return result

    async def __run(self):
        pending_req = []
        async with aiohttp.ClientSession() as session:
            for url in self.url_arr:
                r = self.__fetch(session, url)
                pending_req.append(r)
        #Awaiting the results altogether instead of one by one
        result = await asyncio.wait(pending_req)
        return result

    @staticmethod
    async def __fetch(session, url):
        async with session.get(url) as response: #ERROR here
            status_code = response.status
            if status_code == 200:
                return await response.json()
            else:
                result = await response.text()
                print('Error ' + str(response.status_code) + ': ' + result)
                return {"error": result}

一个接一个地等待结果在异步中似乎毫无意义。我把他们排成一排,一起等 await asyncio.wait(pending_req) .

但似乎这不是正确的方法,因为我得到以下错误

使用会话获取异步。获取(url)作为响应:运行时错误:会话已关闭

我能知道正确的方法吗?谢谢。