How to run an infinite loop on Menu?

Thomas Jollans tjol at
Mon Dec 3 04:03:40 EST 2018

On 03/12/2018 08:58, huey.y.jiang at wrote:
> Hi Folks,
> I need to run an infinite loop on a Menu button, like this:
> from Tkinter import *
> def run_job():
>     i = 0
>     while 1:
>         i = i + 1
>         if i > 100:
>             break
>      .......
> root = Tk()
> menu = Menu(root)
> root.config(menu=menu)
> filemenu = Menu(menu)
> menu.add_cascade(label="Jobs", menu=filemenu)
> filemenu.add_command(label="Run", command=run_job)
> mainloop()
> In fact, the def run_job has more things to do. But, it is an infinite loop in essence. It works. However, when the def run_job is running, the menu will be hang there. I have no way to stop it. Even if I raise it with Key-Interupt, the thing was the same: the infinite loop cannot be stopped nicely. The only way was to wait until the Python interpreter notice the problem, and popped out an error message, then I can kill the running program.

Basic rule of thumb for GUI programming: never block the main (GUI)
thread, i.e. never run any long-running task in the main thread.

If you want to start a long-running task from a GUI event, start a
worker thread; from there, you could then perhaps update a progress bar
in your loop. If you want to be able to stop the task from the GUI,
you'll want something like a "stop the task ASAP please" flag/variable
set by the stop button that the loop periodically checks.

> Can anybody tell me how to handle this? I wish when variable i reached 100, the run_job will be end, and the Menu "Run" will be free.
> Thanks in advance. 

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