为什么 pywin32 服务没有正确停止？

Question

我想将 websocket 服务器作为 Windows 服务运行。 通过从 Python 角落复制和修改用于创建服务的代码，我能够创建一个简单的回显服务器：

https://www.thepythoncorner.com/2018/08/how-to-create-a-windows-service-in-python/

我使用了这里的代码：

https://websockets.readthedocs.io/en/stable/intro.html

创建 websocket 回显服务器。

我可以安装服务：

python create_service.py install

启动服务：

python create_service.py start

套接字服务器正常运行。但是当我尝试像这样停止服务时：

python create_service.py stop

和：

python create_service.py remove

我得到确认

stopping service

和

Service removed

在控制台中。但是在状态下的任务管理器中，它说：停止挂起。 此外，websocket 仍在响应客户端。所以，显然它挂了。

最终我可以使用 taskkill 杀死它，但肯定有问题。 我只能通过 websocket 看到这种行为。像原始示例中的其他代码启动和停止都很好。所以我猜它与python的asyncio有关。 有没有人有这个问题的经验或更深入了解这里发生的事情？

复制的基类代码（service_base.py）：

'''
SMWinservice
by Davide Mastromatteo

Base class to create winservice in Python
-----------------------------------------

Instructions:

1. Just create a new class that inherits from this base class
2. Define into the new class the variables
   _svc_name_ = "nameOfWinservice"
   _svc_display_name_ = "name of the Winservice that will be displayed in scm"
   _svc_description_ = "description of the Winservice that will be displayed in scm"
3. Override the three main methods:
    def start(self) : if you need to do something at the service initialization.
                      A good idea is to put here the inizialization of the running condition
    def stop(self)  : if you need to do something just before the service is stopped.
                      A good idea is to put here the invalidation of the running condition
    def main(self)  : your actual run loop. Just create a loop based on your running condition
4. Define the entry point of your module calling the method "parse_command_line" of the new class
5. Enjoy
'''

import socket

import win32serviceutil

import servicemanager
import win32event
import win32service


class SMWinservice(win32serviceutil.ServiceFramework):
    '''Base class to create winservice in Python'''

    _svc_name_ = 'pythonService'
    _svc_display_name_ = 'Python Service'
    _svc_description_ = 'Python Service Description'

    @classmethod
    def parse_command_line(cls):
        '''
        ClassMethod to parse the command line
        '''
        win32serviceutil.HandleCommandLine(cls)

    def __init__(self, args):
        '''
        Constructor of the winservice
        '''
        win32serviceutil.ServiceFramework.__init__(self, args)
        self.hWaitStop = win32event.CreateEvent(None, 0, 0, None)
        socket.setdefaulttimeout(60)

    def SvcStop(self):
        '''
        Called when the service is asked to stop
        '''
        self.stop()
        self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING)
        win32event.SetEvent(self.hWaitStop)

    def SvcDoRun(self):
        '''
        Called when the service is asked to start
        '''
        self.start()
        servicemanager.LogMsg(servicemanager.EVENTLOG_INFORMATION_TYPE,
                              servicemanager.PYS_SERVICE_STARTED,
                              (self._svc_name_, ''))
        self.main()

    def start(self):
        '''
        Override to add logic before the start
        eg. running condition
        '''
        pass

    def stop(self):
        '''
        Override to add logic before the stop
        eg. invalidating running condition
        '''
        pass

    def main(self):
        '''
        Main class to be ovverridden to add logic
        '''
        pass

# entry point of the module: copy and paste into the new module
# ensuring you are calling the "parse_command_line" of the new created class
if __name__ == '__main__':
    SMWinservice.parse_command_line()

我修改后的服务创建者（create_service.py）：

import time
import random
from pathlib import Path
from service_base import SMWinservice

import asyncio
import websockets

async def hello(websocket, path):
    name = await websocket.recv()
    print(f"< {name}")

    greeting = f"Hello {name}!"

    await websocket.send(greeting)
    print(f"> {greeting}")


class MyService(SMWinservice):
    _svc_name_ = "_MyService"
    _svc_display_name_ = "Winservice Example"
    _svc_description_ = "Simple example for a service"

    def start(self):
        self.isrunning = True

    def stop(self):
        self.isrunning = False

    def main(self):
        start_server = websockets.serve(hello, "localhost", 8765)
        asyncio.get_event_loop().run_until_complete(start_server)
        asyncio.get_event_loop().run_forever()

if __name__ == '__main__':
    MyService.parse_command_line()

websocket 客户端（client.py）：

import asyncio
import websockets

async def hello():
    uri = "ws://localhost:8765"
    async with websockets.connect(uri) as websocket:
        name = input("What's your name? ")

        await websocket.send(name)
        print(f"> {name}")

        greeting = await websocket.recv()
        print(f"< {greeting}")

asyncio.get_event_loop().run_until_complete(hello())

Answer 1

您对stop() 方法的实现除了设置一个标志，表明您的其余代码不会以任何方式检查之外，不会做任何事情。

stop() 的实现实际上应该停止服务，在您的情况下通过停止事件循环。这可以通过调用loop.stop() 来完成，注意使用线程安全API，因为stop() 可能是从不同的线程调用的。例如，您可以：

• 修改main分配self.loop = asyncio.get_event_loop()，和
• 修改stop调用self.loop.call_soon_threadsafe(self.loop.stop)。