Tkinter - Creating a responsive GUI with a progressbar

Question

Using PyGubu (tool to create Tkinter interfaces) I obtained the following GUI:

Current situation:

When I click the Button "Create", a function is called. This function takes quite some time, and the graphical interfaces is just frozen. As I would like to keep the graphical interface and the functional part as much separated as possible, I don't want to update the Progress Bar or the interface in general from the function I call

Desired situation

The best case for me would be a solution without Threading: I would like, upon clicking "Create", that my function runs, while the Progress Bar updates itself (just to show a feedback to the user, and to tell him "look, I am doing something") and the interface remains responsive, so the user can actually interact with it while the function finish.

Current attempts

I tried to solve this using Threading:

#I have this code in my main.py:
from threading import Thread 
from queue import Queue, Empty
my_queue=Queue()

#And this is a simplified version of the Command of the "Create" Button:
def create_command(self):
    #Show the progress bar and start it
    self.show_item(self.progress)
    self.progress.start()

    #Run the big function
    thrd = Thread(target = my_big_function, args=(some_arguments, my_queue))
    thrd.start()

    
    do_retry = True
    while do_retry:                      #Repeat until you have a result
        try:
            result = my_queue.get(False) #If you have a result, exit loop. Else, throw Empty
            do_retry = False
        except Empty:                    #Queue is still empty
            self.progress_var.set(self.progress_var.get()+1)
            sleep(0.05)
            self.mainwindow.update()     #Update the progress bar
 
    q.task_done()                        
    self.progress.stop()

Problem of the current attempt

As I am not used to work with threads, I am facing two problems:

1. In some runs (not all of them, just some) I have a RuntimeError stating

   RuntimeError: main thread is not in main loop I tried to overcome this looking at other question in StackOverflow, but now it just happens randomly, and I don't know how to avoid it. The module mtTinker is no more maintained for python 3.x (there is a vague attempt full of ToDoes and blood)

2. If there is some kind of exception in the big function, I don't know how to handle it. The program would just run forever waiting for a result that will never come back

So

How can I obtain my desired outcome? Thanks in advance

Answer 1

You can try adding root.update() inside the function you call, inside the main loop. Hope that's helpful!