o_18ufhmfmq19t513t3lgmn5l1qa8a.pdf

CHAPTER 14 ■ NETWORK PROGRAMMING 305
Forking and Threading with SocketServers
Creating a forking or threading server with the SocketServer framework is so simple it hardly needs
any explanation. Listings 14-4 and 14-5 show you how to make the server from Listing 14-3 forking
and threading, respectively. The forking and threading behavior is, of course, only useful if the
handle method takes a long time to finish. Note that forking doesn’t work in Windows.
Listing 14-4. A Forking Server
from SocketServer import TCPServer, ForkingMixIn, StreamRequestHandler
class Server(ForkingMixIn, TCPServer): pass
class Handler(StreamRequestHandler):
def handle(self):
addr = self.request.getpeername()
print 'Got connection from', addr
self.wfile.write('Thank you for connecting')
server = Server(('', 1234), Handler)
server.serve_forever()
Listing 14-5. A Threading Server
from SocketServer import TCPServer, ThreadingMixIn, StreamRequestHandler
class Server(ThreadingMixIn, TCPServer): pass
class Handler(StreamRequestHandler):
def handle(self):
addr = self.request.getpeername()
print 'Got connection from', addr
self.wfile.write('Thank you for connecting')
server = Server(('', 1234), Handler)
server.serve_forever()
Asynchronous I/O with select and poll
When a server communicates with a client, the data it receives from the client may come in fits
and spurts. If you’re using forking and threading, that’s not a problem. While one parallel waits
for data, other parallels may continue dealing with their own clients. Another way to go, however,
is to deal only with the clients that actually have something to say at a given moment. You don’t
even have to hear them out—you just hear (or, rather, read) a little bit, and then put it back in
line with the others.