在python服务器进程之间共享列表

Question

我有简单的UDPServer,它适用于多处理.

我想创建一个列表,其中包含有关所有客户端的信息.

我使用Manager,但我不明白,如何在列表中添加信息 - 我需要转移Manager的对象来处理,但是如何处理？我的新属性方式不起作用.

import multiprocessing
from socketserver import UDPServer, ForkingMixIn, DatagramRequestHandler
from socket import socket, AF_INET, SOCK_DGRAM
from settings import host, port, number_of_connections

class ChatHandler(DatagramRequestHandler):

    def handle(self):
        cur_process = multiprocessing.current_process()
        data = self.request[0].strip()
        socket = self.request[1]
        ChatHandler.clients.append(self.client_address) # error here
        print(ChatHandler.clients)


class ChatServer(ForkingMixIn, UDPServer):
    pass


if __name__ == '__main__':
    server = ChatServer((host, port), ChatHandler)
    ChatHandler.clients = multiprocessing.Manager().list()
    server_process = multiprocessing.Process(target=server.serve_forever)
    server_process.daemon = False
    server_process.start()

如何解决？谢谢!

输出:

Exception happened during processing of request from ('127.0.0.1', 55679)
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/managers.py", line 724, in _callmethod
    conn = self._tls.connection
AttributeError: 'ForkAwareLocal' object has no attribute 'connection'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/socketserver.py", line 584, in process_request
    self.finish_request(request, client_address)
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/socketserver.py", line 344, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/socketserver.py", line 665, in __init__
    self.handle()
  File "server.py", line 15, in handle
    ChatHandler.clients.append(self.client_address)
  File "<string>", line 2, in append
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/managers.py", line 728, in _callmethod
    self._connect()
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/managers.py", line 715, in _connect
    conn = self._Client(self._token.address, authkey=self._authkey)
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/connection.py", line 495, in Client
    c = SocketClient(address)
  File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/connection.py", line 624, in SocketClient
    s.connect(address)
FileNotFoundError: [Errno 2] No such file or directory

Answer 1

问题是您在启动工作进程后立即让主进程完成执行.当创建的进程multiprocessing.Manager完成其执行时,Manager服务器将关闭,这意味着您的共享列表对象现在无用.发生这种情况是因为该Manager对象将其shutdown函数注册为multiprocessing模块的"终结器" ,这意味着它将在进程退出之前运行.这是注册它的代码,在BaseManager.__init__:

    # register a finalizer
    self._state.value = State.STARTED
    self.shutdown = util.Finalize(
        self, type(self)._finalize_manager,
        args=(self._process, self._address, self._authkey,
              self._state, self._Client),
        exitpriority=0
        )

这是实际关闭的代码:

@staticmethod
def _finalize_manager(process, address, authkey, state, _Client):
    '''
    Shutdown the manager process; will be registered as a finalizer
    '''
    if process.is_alive():
        util.info('sending shutdown message to manager')
        try:
            conn = _Client(address, authkey=authkey)
            try:
                dispatch(conn, None, 'shutdown')
            finally:
                conn.close()
        except Exception:
            pass

        process.join(timeout=1.0)
        if process.is_alive():
            util.info('manager still alive')
            if hasattr(process, 'terminate'):
                util.info('trying to `terminate()` manager process')
                process.terminate()
                process.join(timeout=0.1)
                if process.is_alive():
                    util.info('manager still alive after terminate')

    state.value = State.SHUTDOWN
    try:
        del BaseProxy._address_to_local[address]
    except KeyError:
        pass

修复很简单 - 不要让主进程立即完成启动运行UDP服务器的进程,方法是调用server_process.join():

import multiprocessing
from socketserver import UDPServer, ForkingMixIn, DatagramRequestHandler
from socket import socket, AF_INET, SOCK_DGRAM
from settings import host, port, number_of_connections

class ChatHandler(DatagramRequestHandler):

    def handle(self):
        cur_process = multiprocessing.current_process()
        data = self.request[0].strip()
        socket = self.request[1]
        ChatHandler.clients.append(self.client_address) # error here
        print(ChatHandler.clients)


class ChatServer(ForkingMixIn, UDPServer):
    pass


if __name__ == '__main__':
    server = ChatServer((host, port), ChatHandler)
    ChatHandler.clients = multiprocessing.Manager().list()
    server_process = multiprocessing.Process(target=server.serve_forever)
    server_process.daemon = False
    server_process.start()
    server_process.join() # This fixes the issue.