Problem using SocketServer.ThreadingTCPServer on Windows?
Panu A Kalliokoski
pkalliok at cc.helsinki.fi
Thu May 31 07:26:31 EDT 2001
xtian <xtian at paradise.net.nz> wrote:
> Obviously, the only way to get more than one connection at a time to a
> server using synchronous sockets is by using multithreading.
Ah! You're planning on using threads. I didn't understand that, it didn't
cross my mind at all... I'm so used to using select(). It's a lot easier
to use, if you ask me.
People use the words synchronous and asynchronous very misleadingly. In
today's world, there are at least four alternatives to make a multiplexing
- synchronous one-socket server with UDP; has to do the bookkeeping of
open UDP "connections" itself
- asynchronous threaded server with synchronous, non-multiplexed threads
with one socket each (your choice, if I understand correctly)
- syncronous, threaded multiplexed server with select() (my choice)
- asynchronous multiplexed server with data delivery notifications,
> Granted, an asynchronous framework would give better scalability, but
> the concepts are a bit more complicated, as far as I've seen. There
It's all about how you're used to doing it. Threaded servers bring subtle
race conditions in inter-thread communications and locking. It's not an
insoluble problem, but neither is select()ing. For me, select()ing is both
better scalable and easier to use.
> are lots of examples in Java using the same structure I'm using,
> presumably because they're conceptually very simple.
For me, it seems simple on the I/O side and very complex on the internal
communications side. But this is a standard holy war issue, so no point
arguing (I hope I'm not doing that).
> Actually, I hadn't even looked at asynchat - it might be just what I
> need. I've downloaded your selecting package - can you give examples
> of how it might be used? I'm not really familiar with asynchronous
The TCPServer is used like this:
class MyChannelHandler (ChannelHandler):
def receive(s, data):
# do something with data
def reg_conn(s, conn):
s.conn = conn
def send(s, data):
mgr = SelectManager()
mgr.add_channel(ServerSocket(('', SERVER_PORT), MyHandlerFactory())
Everytime the ServerSocket gets a connection, it builds a new channel with
a new channel handler (which you get to define in MyChannelHandler). The
receive() callback of the channel handlers is called upon reception of
data. Any data can be sent back to the connection by calling the channel
handler's send() (which moves the data forth to connection's write()). And
this all happens in one thread, so that you can know there's only one
receive() call taking place at any time.
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