Python3 asyncio-在自己的线程中运行两个服务器

Question

我有从BaseServer继承的服务器类：

class BaseServer(object):

    def __init__(self, host, port):
        self.loop = asyncio.new_event_loop()
        asyncio.set_event_loop(self.loop)

        self.instance = asyncio.start_server(self.handle_connection, host = host, port = port)

    async def handle_connection(self, reader: StreamReader, writer: StreamWriter):
        pass

    def start(self):
        # wrapping coroutine into ensure_future to allow it to call from call_soon
        # wrapping into lambda to make it callable
        callback = asyncio.ensure_future(self.instance)
        self.loop.call_soon(lambda: callback)
        self.loop.run_forever()
        self.loop.close()

    def stop(self):
        self.loop.call_soon_threadsafe(self.loop.stop)

    @staticmethod
    def get_instance():
        return BaseServer(None, None)

我需要在自己的线程中运行的两个服务器来并行处理请求。 但是，当我尝试根据需要运行它们时，只有第一台服务器正在运行。 下面是我的运行方式：

if __name__ == '__main__':
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)

    async def run():
        pool = ThreadPoolExecutor(max_workers=cpu_count())

        await loop.run_in_executor(pool, Server1.get_instance().start)
        await loop.run_in_executor(pool, Server2.get_instance().start)

    loop.run_until_complete(run())

1. 我究竟做错了什么？ 如何在自己的线程中运行每个服务器？
2. 当asyncio.set_event_loop从调用def __init__我得到了一个错误：

RuntimeError：线程“ Thread-1”中没有当前事件循环。

但是，如果我从def __init__删除asyncio.set_event_loop并将其移至def start错误将消失。 为什么会这样？

Answer 1

跟进OP的评论：

但是在同一个循环中通过run_until_complete运行两个服务器，其中一个服务器处理对另一个服务器的请求，不是吗？ 如何正确运行两台服务器？

这是python 3.5的asyncio文档中TCP服务器示例的修改版本：

# Start server 1
coro1 = asyncio.start_server(handle_echo, '127.0.0.1', 8888, loop=loop)
server1 = loop.run_until_complete(coro1)
print('Serving 1 on {}'.format(server1.sockets[0].getsockname()))

# Start server 2
coro2 = asyncio.start_server(handle_echo, '127.0.0.1', 8889, loop=loop)
server2 = loop.run_until_complete(coro2)
print('Serving 2 on {}'.format(server2.sockets[0].getsockname()))

# Serve requests until Ctrl+C is pressed
try:
    loop.run_forever()
except KeyboardInterrupt:
    pass

# Close the servers
server1.close()
loop.run_until_complete(server1.wait_closed())
server2.close()
loop.run_until_complete(server2.wait_closed())

# Close the loop
loop.close()

请注意，使用python 3.7对asyncio的添加，它看起来会更好 ：

async def main():
    server1 = await asyncio.start_server(
        handle_echo, '127.0.0.1', 8888)

    addr1 = server1.sockets[0].getsockname()
    print(f'Serving 1 on {addr1}')

    server2 = await asyncio.start_server(
        handle_echo, '127.0.0.1', 8889)

    addr2 = server2.sockets[0].getsockname()
    print(f'Serving 2 on {addr2}')

    async with server1, server2:
        await asyncio.gather(
            server1.serve_forever(), server2.serve_forever())

asyncio.run(main())