Python Forum

Hello. New to threading and appear to be loosing control of the threads and cant seem to figure out how to do this correctly.

I have an app (main) that reads a bunch of sensors and sleeps for a few minutes at a time. I have network sessions coming in and my understanding is that needs to be in a continuous loop. So I made that its own thread. When a client connects, it starts up a thread for each client in a handler. The issue is I can not figure out how to close the child/grandchild threads. If I 'control + c' my main app, it still can take connections somehow. Any help you could sent me on how to do this properly would be greatly appreciated. The code I have (for threading) has been taken in snippits from other code I have found along the way. In the example code below, the counting in the while loop at the bottom simulates my sensor reading main loop.

Im thinking, from what I have read, I need some way to send something to the threads to tell them to stop, so maybe a variable that can be passed to them that could control their while loop if they were a class instead of a def func. How could the main app know how many of the grandchild threads were created and have them exit?

Currently, if I close out the main thread, the client threads stay open until I think the TCP session times out. If I try to rerun the app too soon, it tells me the ports are already open and fails.

import socket 
import threading

HEADER = 64
PORT = 5050
SERVER = socket.gethostbyname(socket.gethostname())

ADDR = (SERVER, PORT)
FORMAT = 'utf-8'
DISCONNECT_MESSAGE = "!DISCONNECT"
tcount = 0

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(ADDR)

def handle_client(conn, addr):
   # print("[NEW CONNECTION] {%d} connected." % addr)

    connected = True
    while connected:
        msg_length = conn.recv(HEADER).decode(FORMAT)
        if msg_length:
            msg_length = int(msg_length)
            msg = conn.recv(msg_length).decode(FORMAT)
            if msg == DISCONNECT_MESSAGE:
                connected = False

            print("{%s}" % msg)
            conn.send("Msg received".encode(FORMAT))
            conn.close()
        

def listen():
    global tcount
    server.listen()
    print("[LISTENING] Server is listening on {%s}" % SERVER)
    while True:
        conn, addr = server.accept()
        thread = threading.Thread(target=handle_client, args=(conn, addr))
        thread.start()
        tcount = threading.activeCount() - 1
        #print("[ACTIVE CONNECTIONS] {%d}" % tcount)

try:
    
    print("[STARTING] server is starting...")
    t1 = threading.Thread(target=listen)
    t1.start()
    x = 1
    while (x > 0):
        print(x)
        print("[ACTIVE CONNECTIONS] {%d}" % tcount)
        x = x + 1
except KeyboardInterrupt:
    t1.join()
    thread.join()