How should I close the TCP server when I close the QMainWindow?

Question

I have a QMainWindow application launched from shell, when it is launched I want it to also run the tcpserver, so I used multiprocess. Next I wanted when I close the QMainWindow it should also close the tcp server process. but instead it stays open. I have tried to use close_event initialised at the module level. but that did not help.

import os
import multiprocessing
import sys
from remote_tcp import main as _run_server
exit_event = multiprocessing.Event()


class MyQMainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self._init_ui()
        # self.triggers()
        self.connections()

    def _init_ui(self):
        loader = QUiLoader()
        app_path = os.path.dirname(__file__)
        ui_file = QFile(os.path.join(app_path, "resources", "utex.ui"))
        ui_file.open(QFile.ReadOnly)
        self.ui = loader.load(ui_file)
        ui_file.close()
        self.setCentralWidget(self.ui)


    def closeEvent(self, event):
        exit_event.set()
        super().closeEvent(event)

def app_launcher(event):
    app = QApplication(sys.argv)
    window = MyQMainWindow()
    window.closeEvent = lambda event: exit_event.set()
    window.show()
    app.exec_()


def tcp_server_launcher(event):
    os.environ["PROMETHEUS_MULTIPROC_DIR"] = "/tmp/"
    event.set()
    _run_tcp_server()


def main():
    tcp_server_process = multiprocessing.Process(target=tcp_server_launcher, args=(exit_event,))
    main_window_process = multiprocessing.Process(target=app_launcher, args=(exit_event,))

    # Start the processes
    tcp_server_process.start()
    main_window_process.start()

    # Wait for the QMainWindow to close or exit_event to be set
    main_window_process.join()

    # Signal the Obex server to exit
    exit_event.set()

    # Wait for the TCP server to finish
    tcp_server_process.join()

    print("You are offline.")

if __name__ == "__main__":
    sys.exit(main())