RuntimeError: threads can only be started once

[Raysz]

Like this:

import tkinter as tk
import schedule
import time
import threading


def job():
    print("I'm working...")  # this is just for testing
    return schedule.CancelJob  # remove it from the scheduler


def time_up():
    schedule.clear()
    print('time has elapsed')  # this is just for testing


def schedule_time():
    """Add a job to the scheduler"""
    schedule.every().day.at(start_time.get()).do(job)
    schedule.every().day.at(stop_time.get()).do(time_up)


def schedule_thread():
    """Run pending jobs."""
    while running:
        # For debugging, print list of pending jobs.
        time.sleep(10)
        print(schedule.get_jobs())
        schedule.run_pending()


def end_program():
    """End schedule thread so program can exit."""
    global running
    running = False
    root.destroy()


root = tk.Tk()
root.protocol("WM_DELETE_WINDOW", end_program)
start_time = tk.StringVar()
tk.Label(root, text='Start (HH:MM[:SS]):').grid(row=0, column=0, padx=10, pady=10)
tk.Entry(root, width=8, textvariable=start_time).grid(row=0, column=1, padx=10)
stop_time = tk.StringVar()
tk.Label(root, text='Stop (HH:MM[:SS]):').grid(row=1, column=0, padx=10, pady=10)
tk.Entry(root, width=8, textvariable=stop_time).grid(row=1, column=1, padx=10)
tk.Button(
    root, text="Run", command=schedule_time
).grid(row=2, column=0, columnspan=2, padx=10, pady=10, sticky="news")

running = True
scheduler_thread = threading.Thread(target=schedule_thread)
scheduler_thread.start()

root.mainloop()

At the start of the program create a thread that runs the schedule. This thread runs for the entirety of the program. The run button adds a new job to the schedule. Scheduling a job does not start a new thread. When shutting down the program you need to stop the scheduler thread.

Thank you very much for your help it does work the way it's supposed to I appreciate it
I will look it over and compare with what I have and see where I made the error
it's a great learning tool thank you very much

So I do see the difference and I think my problem was threading I didn't quite understand how it worked
I am curious though I was always taught to put my window root = tk.Tk() at the top of my script I'm curious to know why
you put yours on the bottom is that just preference