How do I fix session closed error when using asyncio library

Question

I'm trying write a python script that makes a bunch of parallel http requests. Here is what I have so far.

async def deleteLinkRecords(req_headers):
  async with aiohttp.ClientSession(trust_env=True) as session:
   idm_url = "https://example.com"

   tasks = []
   for id in linkIdArr:
     del_url = idm_url + id
     tasks.append(make_request(session, del_url, req_headers))

  results = await asyncio.gather(*tasks)
  print(results)

async def make_request(session, url, req_headers):
    async with session.delete(url = url, headers = req_headers) as resp:
     return await resp.json()

my_headers = {
   "Authorization": "Bearer XXX"
}

linkIdArr = ["abc", "def"....]

asyncio.run(deleteLinkRecords(req_headers = my_headers))

When I run this script, I am getting the following error.

Traceback (most recent call last):
  File "C:\Users\mycode.py", line 48, in <module>
    asyncio.run(deleteLinkRecords(req_headers = my_headers))
  File "C:\Users\AppData\Local\Programs\Python\Python39\lib\asyncio\runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "C:\Users\AppData\Local\Programs\Python\Python39\lib\asyncio\base_events.py", line 642, in run_until_complete
    return future.result()
  File "C:\Users\mycode.py", line 20, in deleteLinkRecords
    results = await asyncio.gather(*tasks)
  File "C:\Users\mycode.py", line 28, in make_requests
    async with session.delete(url = url, headers = req_headers) as resp:
  File "C:\Users\AppData\Local\Programs\Python\Python39\lib\site-packages\aiohttp\client.py", line 1197, in __aenter__
    self._resp = await self._coro
  File "C:\Users\AppData\Local\Programs\Python\Python39\lib\site-packages\aiohttp\client.py", line 428, in _request
    raise RuntimeError("Session is closed")
RuntimeError: Session is closed

How can I fix this issue?

fogelman · Accepted Answer · 2024-06-18 01:54:03Z

1

If you want to reuse the ClientSession then you must add the asyncio.gather inside the same context manager.

async def deleteLinkRecords(req_headers):
  async with aiohttp.ClientSession(trust_env=True) as session:
   idm_url = "https://example.com"

   tasks = []
   for id in linkIdArr:
     del_url = idm_url + id
     tasks.append(make_request(session, del_url, req_headers))

   results = await asyncio.gather(*tasks)
   print(results)

async def make_request(session, url, req_headers):
    async with session.delete(url = url, headers = req_headers) as resp:
     return await resp.json()

my_headers = {
   "Authorization": "Bearer XXX"
}

linkIdArr = ["abc", "def"....]

asyncio.run(deleteLinkRecords(req_headers = my_headers))

answered Jun 18, 2024 at 1:54

fogelman

261 bronze badge

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unp1ng46l3 · Accepted Answer · 2024-06-18 02:08:07Z

1

Check out this post. Because you are using with to handle your sessions, it closes as soon as it is done. So when you try to use it later it has already been closed.

So for example, instead of

async with aiohttp.ClientSession(trust_env=True) as session:

and

async with session.delete(url = url, headers = req_headers) as resp:

just store the session in a variable like this:

session = aiohttp.ClientSession(trust_env=True)

resp = session.delete(url = url, headers = req_headers)

edited Jun 18, 2024 at 2:08

answered Jun 18, 2024 at 1:55

unp1ng46l3

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