New submission from pen hill <imbenh...@gmail.com>:
When I run the following listing (server_multi.py) by using multiprocessing
module of python, it runs successfully on a Linux machine. However, on a 64-bit
windows machine I get the following error:
pickle.PicklingError: Can't pickle <built-in method recvfrom_into of
_socket.socket object at 0x0000000002D2CF10>: it's not found as
__main__.recvfrom_into
This module is from the book Foundations of Python Network Programming, 2nd
Edition. I am pasting the code with the permission of the author. It seems that
socket "listen_sock" cannot be pickled under 64-bit
Windows, however it can be pickled under Linux. How can we remove this issue on
Windows? It is interesting that if I use the threading module, it works for
both Windows and Linux. Thanks.
server_multi.py :
#usage: $ python server_multi.py localhost process
#!/usr/bin/env python
# Foundations of Python Network Programming - Chapter 7 - server_multi.py
# Using multiple threads or processes to serve several clients in parallel.
import sys, time, lancelot
from multiprocessing import Process
from server_simple import server_loop
from threading import Thread
WORKER_CLASSES = {'thread': Thread, 'process': Process}
WORKER_MAX = 10
def start_worker(Worker, listen_sock):
worker = Worker(target=server_loop, args=(listen_sock,))
worker.daemon = True # exit when the main process does
worker.start()
return worker
if __name__ == '__main__':
if len(sys.argv) != 3 or sys.argv[2] not in WORKER_CLASSES:
print >>sys.stderr, 'usage: server_multi.py interface thread|process'
sys.exit(2)
Worker = WORKER_CLASSES[sys.argv.pop()] # setup() wants len(argv)==2
# Every worker will accept() forever on the same listening socket.
listen_sock = lancelot.setup()
workers = []
for i in range(WORKER_MAX):
workers.append(start_worker(Worker, listen_sock))
# Check every two seconds for dead workers, and replace them.
while True:
time.sleep(2)
for worker in workers:
if not worker.is_alive():
print worker.name, "died; starting replacement worker"
workers.remove(worker)
workers.append(start_worker(Worker, listen_sock))
lancelot.py:
#!/usr/bin/env python
# Foundations of Python Network Programming - Chapter 7 - lancelot.py
# Constants and routines for supporting a certain network conversation.
import socket, sys
PORT = 1060
qa = (('What is your name?', 'My name is Sir Lancelot of Camelot.'),
('What is your quest?', 'To seek the Holy Grail.'),
('What is your favorite color?', 'Blue.'))
qadict = dict(qa)
def recv_until(sock, suffix):
message = ''
while not message.endswith(suffix):
data = sock.recv(4096)
if not data:
raise EOFError('socket closed before we saw %r' % suffix)
message += data
return message
def setup():
if len(sys.argv) != 2:
print >>sys.stderr, 'usage: %s interface' % sys.argv[0]
exit(2)
interface = sys.argv[1]
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind((interface, PORT))
sock.listen(128)
print 'Ready and listening at %r port %d' % (interface, PORT)
return sock
server_simple.py:
#!/usr/bin/env python
# Foundations of Python Network Programming - Chapter 7 - server_simple.py
# Simple server that only serves one client at a time; others have to wait.
import lancelot
def handle_client(client_sock):
try:
while True:
question = lancelot.recv_until(client_sock, '?')
answer = lancelot.qadict[question]
client_sock.sendall(answer)
except EOFError:
client_sock.close()
def server_loop(listen_sock):
while True:
client_sock, sockname = listen_sock.accept()
handle_client(client_sock)
if __name__ == '__main__':
listen_sock = lancelot.setup()
server_loop(listen_sock)
----------
components: None
messages: 127922
nosy: pen hill
priority: normal
severity: normal
status: open
title: Passing a socket to a process (multiprocessing module)
type: crash
versions: Python 2.7
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue11119>
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