通过套接字关闭服务器时通知客户端

Question

I'm creating a socket program. The server is always listening to client request and send a response. When user click button in GUI, the client will send a request to server.

My problem is I want to notify the client that server has been closed when I click close button in GUI in server. I have come up with an idea that create a new connection to client always listen to server, but I think it is wasting resources.

server.py

while True:
    try:
        request = client.recv(BUFSIZE).decode('utf-8')
    except ConnectionResetError:
        logging.info(str(client.getsockname()) + ' has exited')
        break
    except Exception as e:
        continue
    if request:
        try:
            request = json.loads(request)
            response = self.__handle_request(request, client).encode()
            client.send(response)

client.py

# when user client button
sock.send(request)
response = sock.recv().decode()
render(response)

Answer 1

The client socket IS notified when the server socket closes. Your client's sock.recv call will return a zero-length packet, the only instance in which it does so.