Aiohttp，Asyncio：RuntimeError：事件循环已关闭

Question

我有两个脚本，scraper.py 和 db_control.py。在 scraper.py 我有这样的东西：

...
def scrape(category, field, pages, search, use_proxy, proxy_file):
    ...
    loop = asyncio.get_event_loop()

    to_do = [ get_pages(url, params, conngen) for url in urls ]
    wait_coro = asyncio.wait(to_do)
    res, _ = loop.run_until_complete(wait_coro)
    ...
    loop.close()
    
    return [ x.result() for x in res ]

...

在 db_control.py 中：

from scraper import scrape
...
while new < 15:
    data = scrape(category, field, pages, search, use_proxy, proxy_file)
    ...
...

理论上，scraper 应该启动未知次数，直到获得足够的数据。但是当new不是imidiatelly > 15时就会出现这个错误：

  File "/usr/lib/python3.4/asyncio/base_events.py", line 293, in run_until_complete
self._check_closed()
  File "/usr/lib/python3.4/asyncio/base_events.py", line 265, in _check_closed
raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed

但如果我只运行一次 scrape()，脚本就可以正常工作。所以我想重新创建loop = asyncio.get_event_loop() 存在一些问题，我尝试过this 但没有任何改变。我该如何解决这个问题？当然这些只是我的代码的 sn-ps，如果您认为问题可能出在其他地方，完整代码可用here。

Answer 1

方法run_until_complete、run_forever、run_in_executor、create_task、call_at显式检查 循环并在关闭时抛出异常。

引用自文档 - BaseEvenLoop.close:

这是幂等且不可逆的

---

除非你有一些（好的）理由，否则你可以简单地省略结束行：

def scrape(category, field, pages, search, use_proxy, proxy_file):
    #...
    loop = asyncio.get_event_loop()

    to_do = [ get_pages(url, params, conngen) for url in urls ]
    wait_coro = asyncio.wait(to_do)
    res, _ = loop.run_until_complete(wait_coro)
    #...
    # loop.close()
    return [ x.result() for x in res ]

如果你想每次都有一个全新的循环，你不必手动创建它并设置为默认值：

def scrape(category, field, pages, search, use_proxy, proxy_file):
    #...
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)    
    to_do = [ get_pages(url, params, conngen) for url in urls ]
    wait_coro = asyncio.wait(to_do)
    res, _ = loop.run_until_complete(wait_coro)
    #...
    return [ x.result() for x in res ]