cpython/Doc/includes/mp_webserver.py

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#
# Example where a pool of http servers share a single listening socket
#
# On Windows this module depends on the ability to pickle a socket
# object so that the worker processes can inherit a copy of the server
# object. (We import `multiprocessing.reduction` to enable this pickling.)
#
# Not sure if we should synchronize access to `socket.accept()` method by
# using a process-shared lock -- does not seem to be necessary.
#
import os
import sys
from multiprocessing import Process, current_process, freeze_support
from http.server import HTTPServer
from http.server import SimpleHTTPRequestHandler
if sys.platform == 'win32':
import multiprocessing.reduction # make sockets pickable/inheritable
def note(format, *args):
sys.stderr.write('[%s]\t%s\n' % (current_process().name, format%args))
class RequestHandler(SimpleHTTPRequestHandler):
# we override log_message() to show which process is handling the request
def log_message(self, format, *args):
note(format, *args)
def serve_forever(server):
note('starting server')
try:
server.serve_forever()
except KeyboardInterrupt:
pass
def runpool(address, number_of_processes):
# create a single server object -- children will each inherit a copy
server = HTTPServer(address, RequestHandler)
# create child processes to act as workers
for i in range(number_of_processes-1):
Process(target=serve_forever, args=(server,)).start()
# main process also acts as a worker
serve_forever(server)
def test():
DIR = os.path.join(os.path.dirname(__file__), '..')
ADDRESS = ('localhost', 8000)
NUMBER_OF_PROCESSES = 4
print('Serving at http://%s:%d using %d worker processes' % \
(ADDRESS[0], ADDRESS[1], NUMBER_OF_PROCESSES))
print('To exit press Ctrl-' + ['C', 'Break'][sys.platform=='win32'])
os.chdir(DIR)
runpool(ADDRESS, NUMBER_OF_PROCESSES)
if __name__ == '__main__':
freeze_support()
test()