为什么在这种情况下事件循环会关闭？

Question

我正在使用aiohttp==2.3.10，python3.5，Django==2.1.3

我的目录结构如下：

├─project1
   ├─app1
     ├─management
       ├─commands
         └─pull_campaign_list_every_15m.py 

我的主要代码：

class Command(BaseCommand):
    help = "pull campaign data"

    def handle(self, *args, **options):

       # get related data here 

        task_list = []
        for account_info in account_data_list:
            #...
            campaign_list = [campaign_list_data,...,] # get from http request
            task_list.extend([
                    asyncio.ensure_future(
                        _handle_campaign_list(related_param)) for campaign in
                    campaign_list if campaign_list
                ])
        loop = asyncio.get_event_loop()
        try:
            loop.run_until_complete(asyncio.wait(task_list))
        except Exception as e:
            info_logger.info(e)
        finally:
            loop.close()

async def _handle_campaign_list(realated_param):
    # do something here batch handle list data
    try:
        async with  aiohttp.ClientSession() as session:
            async with session.get(url) as response:
                result = await response.text()
            temp_data = json.loads(result)

            # save data here using Django ORM

    except aiohttp.client_exceptions.ClientConnectorError:
        info_logger.info("bad request connect error")

    except asyncio.TimeoutError:
        info_logger.info("server timeout")

当我调用python manage.py pull_campaign_list_every_15m之类的命令时，出现如下错误：

    Traceback (most recent call last):
      File "manage.py", line 15, in <module>
        execute_from_command_line(sys.argv)
      File "/home/.virtualenvs/project1/lib/python3.5/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
        utility.execute()
      File "/home/.virtualenvs/project1/lib/python3.5/site-packages/django/core/management/__init__.py", line 375, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/home/.virtualenvs/project1/lib/python3.5/site-packages/django/core/management/base.py", line 316, in run_from_argv
        self.execute(*args, **cmd_options)
      File "/home/.virtualenvs/project1/lib/python3.5/site-packages/django/core/management/base.py", line 353, in execute
        output = self.handle(*args, **options)
      File "/home/project1/app1/management/commands/pull_campaign_list_every_15m.py", line 77, in handle
        campaign_list if campaign_list
      File "/home/project1/app1/management/commands/pull_campaign_list_every_15m.py", line 77, in <listcomp>
        campaign_list if campaign_list
      File "/usr/local/lib/python3.5/asyncio/tasks.py", line 547, in ensure_future
        task = loop.create_task(coro_or_future)
      File "/usr/local/lib/python3.5/asyncio/base_events.py", line 259, in create_task
        self._check_closed()
      File "/usr/local/lib/python3.5/asyncio/base_events.py", line 334, in _check_closed
        raise RuntimeError('Event loop is closed')
    RuntimeError: Event loop is closed
    sys:1: RuntimeWarning: coroutine '_handle_campaign_list' was never awaited

为什么在这种情况下事件循环关闭？任何帮助或见识将不胜感激，非常感谢。