add the multiprocessing package to fulfill PEP 371

Doc/includes/mp_webserver.py

@@ -0,0 +1,67 @@
+#
+# 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 BaseHTTPServer import HTTPServer
+from SimpleHTTPServer 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().get_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()