Updating a tk ProgressBar from a multiprocess.proccess in python3

Doing something similar, I ended up having to use a combination of threads and processes - the GUI front end had two threads: one for tkinter, and one reading from a multiprocessing.Queue and calling gui.update() - then the back-end processes would write updates into that Queue

This might be a strange approach, but it works for me. Copy and paste this code to a file and run it to see the result. It's ready to run.

I don't have the patience to explain my code right now, I might edit it another day.

Oh, and this is in Python 2.7 I started programming two months ago, so I have not idea if the difference is relevant.

# -*- coding: utf-8 -*-# threadsandprocesses.py# Importing modulesimport timeimport threadingimport multiprocessingimport Tkinter as tkiimport ttkclass Master(object):    def __init__(self):        self.mainw = tki.Tk()        self.mainw.protocol("WM_DELETE_WINDOW", self.myclose)        self.mainw.title("Progressbar")        self.mainw.geometry('300x100+300+300')        self.main = tki.Frame(self.mainw)        self.RunButton = ttk.Button(self.main, text='Run',                                    command=self.dostuff)        self.EntryBox = ttk.Entry(self.main)        self.EntryBox.insert(0, "Enter a number")        self.progress = ttk.Progressbar(self.main,                                        mode='determinate', value=0)        self.main.pack(fill=tki.BOTH, expand=tki.YES)        self.progress.pack(expand=tki.YES)        self.EntryBox.pack(expand=tki.YES)        self.RunButton.pack()        print "The Master was created"    def dostuff(self):        print "The Master does no work himself"        data = range(int(self.EntryBox.get()))        S = Slave(self, data)        print "The Master created a Slave to do his stuff"        print "The Slave gets told to start his work"        S.start()    def myclose(self):        self.mainw.destroy()        return    def nextstep(self):        print "Good job, Slave, I see the result is"        print Master.results.get()class Slave(threading.Thread):    def __init__(self, guest, data):        print "This is the Slave."        print "Nowdays, Work is outsourced!"        self.data = data        self.guest = guest        threading.Thread.__init__(self)    def run(self):        print "The Slave is outsourcing his work to Calcualte inc."        time.sleep(1)        Outsourcing = Calculate()        Results = Outsourcing.run(self.guest, self.data)        return Results# unwrapping outside a classdef calc(arg, **kwarg):    return Calculate.calculate(*arg, **kwarg)class Calculate(object):    def run(self, guest, data):        print"This is Calculate inc. ... how can I help you?"        time.sleep(1)        maximum = int(guest.EntryBox.get())        guest.progress.configure(maximum=maximum, value=0)        manager = multiprocessing.Manager()        queue = manager.Queue()        lock = manager.Lock()        print "Things are setup and good to go"        # Counting the number of available CPUs in System        pool_size = multiprocessing.cpu_count()        print "Your system has %d CPUs" % (pool_size)        # Creating a pool of processes with the maximal number of CPUs possible        pool = multiprocessing.Pool(processes=pool_size)        Master.results = pool.map_async(calc, (zip([self]*len(data), [lock]*len(data),                                        [queue]*len(data), data)))        for job in range(1, maximum+1):            queue.get()  # this is an abuse I think, but works for me            guest.progress.configure(value=job)        # Properly close and end all processes, once we're done        pool.close()        pool.join()        print "All done"        guest.nextstep()        return    def calculate(self, lock, queue, indata):        lock.acquire()        print 'Reading values and starting work'        lock.release()        time.sleep(3)  # some work        results = indata  # The works results        lock.acquire()        print 'Done'        lock.release()        queue.put("Finished!")        return resultsif __name__ == '__main__':    TheMaster = Master()    TheMaster.mainw.mainloop()