CODEWITHSUNDEEP
pythonpython-3.xasync-awaitaiohttp
MatrixTXT
MatrixTXT

Reputation: 2502

Awaiting multiple aiohttp requests cause 'Session is closed' error

I am writing a helper class for handling multiple urls request in asynchronous way. The code is following.

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}

As awaiting the result one by one seems meaningless in asynchronous. I put them into an array and wait together by await asyncio.wait(pending_req).

But seems like it is not the correct way to do it as I get the following error

in __fetch async with session.get(url) as response: RuntimeError: Session is closed

May I know the correct way to do it? Thanks.

Upvotes: 0

Views: 2943

Answers (1)

Kr.98
Kr.98

Reputation: 106

because session has closed before you await it

  async with aiohttp.ClientSession() as session:
        for url in self.url_arr:
            r = self.__fetch(session, url)
            pending_req.append(r)
  #session closed hear

you can make session an argument to __run, like this

async def async_worker(self):
    async with aiohttp.ClientSession() as session:
        result = await self.__run(session)
        return result
    # session will close hear

async def __run(self, session):
    pending_req = []
    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

Upvotes: 1

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