CODEWITHSUNDEEP
python-3.xsockets
b.tchman
b.tchman

Reputation: 112

why can't multiple clients be connected to a server in the same time? Python

So lets say I have a server.py and a client.py with the following code:

server.py

import socket

def listen():
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    host = "127.0.0.1"
    port = 5555

    s.bind((host, port))
    s.listen(128)

    print("LISTENING FOR INCOMING CONNECTIONS")

    c, addr = s.accept()
    print("GOT CONNECTION FROM", addr)

    while True:
        data = c.recv(1024)
        data = data.decode("utf-8")
        data = data.upper()
        c.send(data.encode("utf-8"))
listen()

and client.py

import socket

def connect():
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    host = "127.0.0.1"
    port = 5555

    s.connect((host, port))

    print("CONNECTED TO HOST")

    while True:
        command = input("command> ")
        s.send(command.encode("utf-8"))
        data = s.recv(1024)
        print(str(data.decode("utf-8")))
connect()

And now if I disconnect the client and try to reconnect to the server it won't work. (and by will not work I mean the connection won't get established)

Upvotes: 1

Views: 679

Answers (1)

Mark A
Mark A

Reputation: 948

In your listen function in server.py, you are only calling the accept function once. accept must be called for each client connection you want to accept. To resolve your problem, you can just put the latter part of the function in a loop:

def listen():
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    host = "127.0.0.1"
    port = 5555

    s.bind((host, port))
    s.listen(128)

    while True:
        print("Waiting for an incoming connection...")
        c, addr = s.accept()
        print("GOT CONNECTION FROM", addr)

        # Serve the connection
        try:
            while True:
                data = c.recv(1024)
                if len(data) == 0:
                    print("Client closed connection")
                    break
                data = data.decode("utf-8")
                data = data.upper()
                c.send(data.encode("utf-8"))
        except Exception as e:
            print("Connection died: {}".format(e))

This will mean that only 1 client can be connected at a time.

Instead of writing this type of code yourself, I'd highly recommend taking a look at SocketServer in the Python standard library. This library takes care of the boilerplate listen/accept stuff and also has some advanced features that lets you easily handle more than one client connection at the same time (if you need that)

https://docs.python.org/3/library/socketserver.html#socketserver-tcpserver-example

Upvotes: 1

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