Python 3 Client/server using multiprocessing with asynchronous pipes

MPClient.py

import multiprocessing as mp

import time

import MPServer

if __name__ == "__main__":
    #mp.set_start_method('fork')
    
    print("[Client] start")

    request, reply = mp.Pipe()
    serv = mp.Process(target=MPServer.run_server, args=(reply,))
    serv.start()
    print("[Client] launched server")

    #time.sleep(3)
    print("[Client] send 'test'")
    request.send("test")

    print("[Client] wait loop")
    avail = False
    while not avail:
        print("[Client] wait 1 second")
        avail = request.poll(1)

    msg = request.recv()
    print("[Client] receives '{}'".format(msg))
    print("[Client] terminates server")
    serv.terminate() 
    serv.join()
    print("[Client] stop")

    

MPServer.py

import multiprocessing as mp

import tkinter as tk

def run_server(reply):
    
    print("[Server] started")
    
    req = reply.recv()
    print("[Server] received '{}'".format(req))

    window = tk.Tk()
    button = tk.Button(window, text=str(req), command=quit_server(reply))
    button.pack()
    
    window.mainloop()

def quit_server(reply):
    def callback():
        print("[Server] send 'quit'")
        reply.send('quit')
        print("[Server] wait for termination")

    return callback