async 运行多线程时报错RuntimeError: There is no current event loop in thread ‘Thread-2（webui中也遇到）
原来使用：
loop = asyncio.get_event_loop()
task = asyncio.ensure_future(do_work(checker))
loop.run_until_complete(asyncio.wait([task]))
st = task.result()
添加了
new_loop = asyncio.new_event_loop()
asyncio.set_event_loop(new_loop)
添加后如下：
new_loop = asyncio.new_event_loop()
asyncio.set_event_loop(new_loop)
loop = asyncio.get_event_loop()
task = asyncio.ensure_future(do_work(checker))
loop.run_until_complete(asyncio.wait([task]))
st = task.result()
然后会报RuntimeError: There is no current event loop in thread 'Thread-2
根本原因在源码中：
def get_event_loop(self):
"""Get the event loop.
This may be None or an instance of EventLoop.
"""
if (self._local._loop is None and
not self._local._set_called and
isinstance(threading.current_thread(), threading._MainThread)):
self.set_event_loop(self.new_event_loop())
if self._local._loop is None:
raise RuntimeError('There is no current event loop in thread %r.'
% threading.current_thread().name)
return self._local._loop
在主线程中，调用get_event_loop总能返回属于主线程的event loop对象，如果是处于非主线程中，还需要调用set_event_loop方法指定一个event loop对象，这样get_event_loop才会获取到被标记的event loop对象：
def set_event_loop(self, loop):
"""Set the event loop."""
self._local._set_called = True
assert loop is None or isinstance(loop, AbstractEventLoop)
self._local._loop = loop
官方文档： https://docs.python.org/3/library/asyncio-eventloop.html
我只截取上述用到的部分,具体详情请前往官方 https://docs.python.org/3/library/asyncio-eventloop.html
参考：
https://github.com/AUTOMATIC1111/stable-diffusion-webui/issues/9441
https://github.com/AUTOMATIC1111/stable-diffusion-webui/issues/9046