python服务器中进程之间的共享列表 [英] Share list between process in python server
问题描述
我有简单的 UDPServer ,它可以与多处理一起使用.
I have simple UDPServer, which works with multiprocessing.
我想创建一个列表,其中包含有关所有客户端的信息.
I want to create a list, that contains information about all clients.
我使用 Manager ,但是我不明白如何在列表中添加信息-我需要传输Manager的对象来处理,但是如何处理?我使用新属性的方法行不通.
I use Manager, but I don't understand, how to append information in list - I need transfer Manager`s object to handle, but how? My way with new attribute does not work.
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()
该如何解决?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
推荐答案
问题是,启动工作进程后,您让主进程立即完成其执行.创建multiprocessing.Manager
的进程完成执行后,Manager
服务器将关闭,这意味着您的共享列表对象现在无用了.发生这种情况是因为Manager
对象在multiprocessing
模块中将其shutdown
函数注册为"finalizer",这意味着它将在进程退出之前运行.这是在BaseManager.__init__
中注册它的代码:
The problem is that you're letting the main process finish its execution immediately after you start the worker process. When the process that created the multiprocessing.Manager
finishes its execution, the Manager
server gets shut down, which means your shared list object is now useless. This happens because the Manager
object registers it's shutdown
function as a "finalizer" with the multiprocessing
module, which means it will be run just before the process exits. Here's the code that registers it, in 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
)
以下是实际执行关闭操作的代码:
Here's the code that actually does the shut down:
@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-通过调用server_process.join()
,不要在启动运行UDP服务器的进程后立即让主进程完成:
The fix is simple - don't let the main process complete immediately you start the process that runs the UDP server, by calling 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.
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