服务器仅打印来自最近连接的客户端的消息

Question

I'm trying to create a server that accepts multiple clients. The clients can send messages to the server, and the server prints these messages. My code below produces a weird result where only the most recent connection has its messages accepted and printed by the server.

server.py

import socket
import _thread

HOST = "192.168.1.84"
PORT = 5000


def client_thread(conn):
    welcome_message = "Connected to server " + HOST + ":" + str(PORT) + "\n"
    conn.send(welcome_message.encode("ascii"))
    while True:
        data = connection.recv(2048)
        message = data.decode("ascii")
        if not data:
            break
        print("(" + address[0] + ":" + str(address[1]) + ") " + message)
    connection.close()


with socket.socket() as server_socket:
    try:
        server_socket.bind((HOST, PORT))
        server_socket.listen(10)
        print("Server hosted on " + HOST + ":" + str(PORT) + "\n")
        while True:
            connection, address = server_socket.accept()
            _thread.start_new_thread(client_thread, (connection,))
            print("Connection from " + address[0] + ":" + str(address[1]))

    except socket.error as error_message:
        print("Error: " + str(error_message))

client.py

import socket

HOST = "192.168.1.84"
PORT = 5000

with socket.socket() as client_socket:
    try:
        client_socket.connect((HOST, PORT))
        data = client_socket.recv(2048)
        print(data.decode("ascii"))
        while True:
            message = input()
            data = message.encode("ascii")
            client_socket.send(data)
    except socket.error as error_message:
        print("Error: " + str(error_message))

Problem Output Behavior:

Client 1 can connect to the server and send messages. The server receives and prints these messages fine.

Now when Client 2 connects to the server, Client 1's messages no longer is sent to the server. Now only Client 2 can send messages to the server and have it printed fine.

To further carry this out, Client 3 connects to the server. Now both Client 1's and Client 2's messages aren't sent to the server, only Client 3's messages are.

Answer 1

Your client_thread function has some issues. conn is the connection passed to the thread, but connection and address are being read from the global namespace. Instead, use the connection passed in and pass the address as well, so each thread is only referring to local variables for the connection/address pair it is responsible for:

def client_thread(conn,addr):
    welcome_message = "Connected to server " + HOST + ":" + str(PORT) + "\n"
    conn.send(welcome_message.encode("ascii"))
    while True:
        data = conn.recv(2048)
        message = data.decode("ascii")
        if not data:
            break
        print("(" + addr[0] + ":" + str(addr[1]) + ") " + message)
    conn.close()

In the main code:

_thread.start_new_thread(client_thread, (connection,address))