Sanic和Motor使用不同的事件循环

我是Sanic的新手，我正试图让它与Motor合作 . 我确实设法让所有东西都在一个文件中工作，但是，当我在我的项目结构中尝试时，我遇到了以下问题 .

[2018-02-28 17:26:58 +0530] [3720] [ERROR] Traceback (most recent call 
last):
File "/usr/local/lib/python3.6/site-packages/sanic/app.py", line 556, in 
handle_request
response = await response
File "/usr/src/Python-3.6.4/Lib/asyncio/coroutines.py", line 129, in throw
return self.gen.throw(type, value, traceback)
File "/home/msambare/Documents/Projects/Snippets/Sanic-Motor-
Issue/IAC/src/MyPackgae/REST/user_REST.py", line 42, in post
request.json['last']
File "/usr/src/Python-3.6.4/Lib/asyncio/coroutines.py", line 129, in throw
return self.gen.throw(type, value, traceback)
File "/home/msambare/Documents/Projects/Snippets/Sanic-Motor-
Issue/IAC/src/MyPackgae/DAO/user_DAO.py", line 40, in register_user
result = await db.users.insert_one(serialized_user)
RuntimeError: Task <Task pending coro=<Sanic.handle_request() running at 
/usr/local/lib/python3.6/site-packages/sanic/app.py:556> created at 
/usr/local/lib/python3.6/site-packages/sanic/server.py:299> got Future 
<Future pending cb=[run_on_executor.<locals>._call_check_cancel() at 
/usr/local/lib/python3.6/site-
packages/motor/frameworks/asyncio/__init__.py:85]> attached to a different 
loop

我做了一些研究，正如Sanic的GitHub页面所提到的，尝试了db setup的'before-server-block'部分 . 这适用于单个文件，但不适用于我的项目结构 .

我的项目结构看起来像：

Project Structure

以下是我的代码 . 我已经在一个更简单的结构中重新创建了这个问题，而没有失去本质 .

SRC / MyPackage的/型号/ user.py

class User(object):
def __init__(self, first, last):
    self.first = first
    self.last = last

SRC / MyPackage的/ UC / user_uc.py

from Model import User
from DAO import User_DAO


class User_UC(object):
    def __init__(self):
        self._user = None

    def create_user(self, first, last):
        self._user = User(first, last)
        ud = User_DAO()
        id = ud.register_user(
            {
                'first': first,
                'last': last
            }
        )
        return id

SRC / DAO / motor_connection.py

import uvloop
import asyncio
import motor.motor_asyncio


asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())


class Motor_Connection(object):
    """ Provides a MongoDB connection and sets the DB to be used.

    The class implements the Singleton pattern.
    """

    __instance = None

    def __new__(cls):
        if Motor_Connection.__instance is None:
            Motor_Connection.__instance = object.__new__(cls)

            Motor_Connection.__instance.client = \
                motor.motor_asyncio.AsyncIOMotorClient(
                    'localhost',
                    27017,
                    io_loop=asyncio.get_event_loop()
                )

            Motor_Connection.__instance.db = \
                Motor_Connection.__instance.client.test_database

        return Motor_Connection.__instance.db

SRC / DAO / user_DAO.py

from DAO import Motor_Connection


db = Motor_Connection()


class User_DAO(object):
    async def register_user(self, serialized_user):
        result = await db.users.insert_one(serialized_user)
        return result.inserted_id

SRC / MyPackage的/ REST / user_REST.py

from sanic.views import HTTPMethodView
from sanic.response import text
from UC import User_UC


class User_REST(HTTPMethodView):
    async def post(self, request):
        user_uc = User_UC()
        id = await user_uc.create_user(
            request.json['first'],
            request.json['last']
        )
        return text(id)

最后是主程序......

SRC / MyPackage的/ main.py

from sanic import Sanic
from DAO import Motor_Connection
from REST import User_REST


app = Sanic()


@app.listener('before_server_start')
def init(sanic, loop):
    global db
    db = Motor_Connection()


app.add_route(User_REST.as_view(), '/')


if __name__ == "__main__":
    app.run(host="0.0.0.0", port=8000, workers=3, debug=True)

我没有包含任何子包的 init .py文件 . 我在这些文件中唯一做的就是将类带到子包级别 .

从我能够弄清楚的，当导入User_Rest类时，似乎在main.py中导入了导入User_DAO类的User_UC类，而User_DAO类又导入了Motor_Connection类 - 这就是混乱发生的地方 . 这将创建一个单独的事件循环，Sanic不会共享该循环 .

因此，如果我的理解是正确的，那么所有链接的导入类都使用一个事件循环，而Sanic使用另一个事件循环 . 我知道我们不能有2个事件循环，但我无法弄清楚需要做些什么才能解决这个问题 .

请帮忙 . 提前致谢 .