asyncio 多线程附加协程，在一个线程内运行一个事件循环

使用threading.Thread 和asyncio.new_event_loop 我们可以创建具有唯一事件循环实例的线程实例。

import asyncio
import threading


def creat_event_loop_thread(worker, *args, **kwargs):
    """"""

    def _worker(*args, **kwargs):
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)

        try:
            loop.run_until_complete(worker(*args, **kwargs))
        finally:
            loop.close()

    return threading.Thread(target=_worker, args=args, kwargs=kwargs)


async def print_coro(*args, **kwargs):
    print(f'Inside the print coro on {threading.get_ident()}', (args, kwargs))


def start_threads(*threads):
    [thread.start() for thread in threads if isinstance(thread, threading.Thread)]


def join_threads(*threads):
    [thread.join() for thread in threads if isinstance(thread, threading.Thread)]


def main():
    workers = [creat_event_loop_thread(print_coro, 22, a=33) for _ in range(10)]
    start_threads(*workers)
    join_threads(*workers)


if __name__ == '__main__':
    main()
    
   
打印
Inside the print coro on 6154842112 ((22,), {'a': 33})
Inside the print coro on 6171668480 ((22,), {'a': 33})
Inside the print coro on 6154842112 ((22,), {'a': 33})
Inside the print coro on 6205321216 ((22,), {'a': 33})
Inside the print coro on 6188494848 ((22,), {'a': 33})
Inside the print coro on 6171668480 ((22,), {'a': 33})
Inside the print coro on 6154842112 ((22,), {'a': 33})
Inside the print coro on 6205321216 ((22,), {'a': 33})
Inside the print coro on 6188494848 ((22,), {'a': 33})
Inside the print coro on 6171668480 ((22,), {'a': 33})

DefaultLoopPolicy检查每个线程的循环，并且不允许通过asyncio.get_event_loop在主线程之外创建循环。

因此，我们必须通过asyncio.set_event_loop(asyncio.new_event_loop()) 创建一个线程的本地事件循环。