tkinter progress bar with joblib parallel

Question

I would like to make a GUI progress bar to show the progress of Joblib.

Here below is what I have done now:

import tkinter as tk
from tkinter import ttk
from tqdm import tqdm
from joblib import Parallel, delayed

def fun(_):
    return _ ** 2
def main():
    result = Parallel(n_jobs=-1, backend='threading')(delayed(fun)(_) for _ in tqdm(range(1024 ** 2)))
    print(result)

root = tk.Tk()
progress_bar = ttk.Progressbar(root, mode='determinate')
progress_bar.pack()
button = tk.Button(root, text='start', command=main)
button.pack()
root.mainloop()

Now it is able to show the progress in the terminal with the tqdm module. But I would like to ask, how can I make it to show the progress with the progress bar in tkinter window?

I have tried to call progress_bar.step() in fun(), but the program just freeze. Sorry that I am unfamiliar with tkinter.

Answer 1

I have kind of solved the question, but I know this is definitely not the best method. Here is my code:

import tkinter as tk
from tkinter import ttk
from tqdm import tqdm
from joblib import Parallel, delayed
from threading import Thread

n = 0

def fun(_):
    global n
    n += 1
    return _ ** 2

def main():
    def parallel():
        nonlocal result
        result = Parallel(n_jobs=-1, backend='threading')(delayed(fun)(_) for _ in range(1024 ** 2))
    
    result = None
    progress_bar['maximum'] = 1024 ** 2  # number of items that loops in Parallel
    process = Thread(target=parallel, daemon=True)
    process.start()
    """
    update progress bar
    """
    while progress_bar['value'] < 1024 ** 2:
        progress_bar['value'] = n
        root.update_idletasks()
        root.update()  # prevent freezing
    process.join()

    print(result)

root = tk.Tk()
progress_bar = ttk.Progressbar(root, mode='determinate')
progress_bar.pack()
button = tk.Button(root, text='start', command=main)
button.pack()
root.mainloop()

For this method, I have used a global variable n to track the progress of Joblib. Also, it is important that the Joblib's task should be a subprocess, otherwise, it will freeze the tk window. I know that using a global variable is not a good habit, but seems the overhead of a global variable in fun() is not high. At least with this method, the progress bar is functionable.