Doc/includes/mp_webserver.py

   1 #
   2 # Example where a pool of http servers share a single listening socket
   3 #
   4 # On Windows this module depends on the ability to pickle a socket
   5 # object so that the worker processes can inherit a copy of the server
   6 # object.  (We import `multiprocessing.reduction` to enable this pickling.)
   7 #
   8 # Not sure if we should synchronize access to `socket.accept()` method by
   9 # using a process-shared lock -- does not seem to be necessary.
  10 #
  11 # Copyright (c) 2006-2008, R Oudkerk
  12 # All rights reserved.
  13 #
  14
  15 import os
  16 import sys
  17
  18 from multiprocessing import Process, current_process, freeze_support
  19 from BaseHTTPServer import HTTPServer
  20 from SimpleHTTPServer import SimpleHTTPRequestHandler
  21
  22 if sys.platform == 'win32':
  23     import multiprocessing.reduction    # make sockets pickable/inheritable
  24
  25
  26 def note(format, *args):
  27     sys.stderr.write('[%s]\t%s\n' % (current_process().name, format%args))
  28
  29
  30 class RequestHandler(SimpleHTTPRequestHandler):
  31     # we override log_message() to show which process is handling the request
  32     def log_message(self, format, *args):
  33         note(format, *args)
  34
  35 def serve_forever(server):
  36     note('starting server')
  37     try:
  38         server.serve_forever()
  39     except KeyboardInterrupt:
  40         pass
  41
  42
  43 def runpool(address, number_of_processes):
  44     # create a single server object -- children will each inherit a copy
  45     server = HTTPServer(address, RequestHandler)
  46
  47     # create child processes to act as workers
  48     for i in range(number_of_processes-1):
  49         Process(target=serve_forever, args=(server,)).start()
  50
  51     # main process also acts as a worker
  52     serve_forever(server)
  53
  54
  55 def test():
  56     DIR = os.path.join(os.path.dirname(__file__), '..')
  57     ADDRESS = ('localhost', 8000)
  58     NUMBER_OF_PROCESSES = 4
  59
  60     print 'Serving at http://%s:%d using %d worker processes' % \
  61           (ADDRESS[0], ADDRESS[1], NUMBER_OF_PROCESSES)
  62     print 'To exit press Ctrl-' + ['C', 'Break'][sys.platform=='win32']
  63
  64     os.chdir(DIR)
  65     runpool(ADDRESS, NUMBER_OF_PROCESSES)
  66
  67
  68 if __name__ == '__main__':
  69     freeze_support()
  70     test()