Scalable client server communication

Question

import socket,time
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('',0))
port=s.getsockname()[1]
s.setblocking(0)
lines=[]
while True:
 try:
 data, addr = s.recvfrom(1024)
 if addr not in clients:
 clients.append(addr)
 if not lines:
 for client in clients:
 s.sendto(lines, client)
 except:
 pass
s.close()

I have paint application, in which the server sends the co-ordinates to a set of clients. I use the above code for sending, launching on a separate thread. This sends data to each client sequentially. This will cause a delay to the clients at the end of the list. Launching a separate thread for each client has scalability issues. Is there is scalabe way to write the above code maybe using async.io?

Answer 1

You cannot use recvfrom with a TCP socket (SOCK_STREAM). You don't see the error, because of your wrong exception handling. Never ignore all exceptions! Don't write your own server, use the appropriate interface from asyncio.

• Abhishek Bhatia: It should be recvinstead? Which interface are talking about, please tell.
• Daniel: What do you want?
• Abhishek Bhatia: I want it to send data to all clients asynchronously.