multiconn_client.py

import sys 
import socket
import selectors
import types

sel = selectors.DefaultSelector()
messages = [b"Message from client 1", b"Message from client 2"]

def start_connection(host, port, num_conns):
    server_addr = (host, port)
    for i in range(0, num_conns):
        connid = i + 1
        print(f"Starting connection to {connid}")
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.setblocking(False)
        sock.connect_ex(server_addr)
        events = selectors.EVENT_READ |selectors.EVENT_WRITE
        data = types.SimpleNamespace(
            connid = connid,
            msg_total = sum(len(m) for m in messages),
            recv_total = 0,
            messages = messages.copy(),
            outb = b"",
        )
        sel.register(sock, events, data=data)

def service_connection(key, mask):
    sock = key.fileobj
    data = key.data
    if mask & selectors.EVENT_READ:
        recv_data = sock.recv(1024) # Should be ready to read
        if recv_data:
            print(f"Recived {recv_data!r} from connection {data.connid}")
            data.recv_total += len(recv_data)
        if not recv_data or data.recv_total == data.msg_total:
            print(f"Closing connection {data.connid}")
            sel.unregister(sock)
            sock.close()
    if mask & selectors.EVENT_WRITE:
        if not data.outb and data.messages:
            data.outb = data.messages.pop(0)
        if data.outb:
            print(f"Sending {data.outb!r} to connection {data.connid}")
            sent = sock.send(data.outb) # Should be ready to write
            data.outb = data.outb[sent:]