Kivy GUI Freezes

Question

My KIVY-GUI freezes randomly and im not too sure why. I change a couple of widgets from python-side (i.e. enabling checkboxes, changing textinput texts and so on), sometimes from loops (i.e. enabling 6 checkboxes one after another). I think the freeze happens mainly when i disable a lot of widgets at once, however it also happens when changing only one widget. By going to the shell window and pressing CTRL+C i can unfreeze the GUI again. Sometimes the GUI then crashes with the following error:

[INFO   ] [Base        ] Leaving application in progress...
 Traceback (most recent call last):
   File "GUI_MELC.py", line 637, in <module>
     GUI_MELC().run()
   File "C:\Python37\lib\site-packages\kivy\app.py", line 855, in run
     runTouchApp()
   File "C:\Python37\lib\site-packages\kivy\base.py", line 504, in runTouchApp
     EventLoop.window.mainloop()
   File "C:\Python37\lib\site-packages\kivy\core\window\window_sdl2.py", line 747, in mainloop
     self._mainloop()
   File "C:\Python37\lib\site-packages\kivy\core\window\window_sdl2.py", line 479, in _mainloop
     EventLoop.idle()
   File "C:\Python37\lib\site-packages\kivy\base.py", line 339, in idle
     Clock.tick()
   File "C:\Python37\lib\site-packages\kivy\clock.py", line 563, in tick
     current = self.idle()
   File "C:\Python37\lib\site-packages\kivy\clock.py", line 543, in idle
     usleep(1000000 * sleeptime)
   File "C:\Python37\lib\site-packages\kivy\clock.py", line 727, in usleep
     _usleep(microseconds, self._sleep_obj)
   File "C:\Python37\lib\site-packages\kivy\clock.py", line 405, in _usleep
     _kernel32.WaitForSingleObject(obj, 0xffffffff)
 KeyboardInterrupt

Some sample code of how i disable widgets (this is probably the most clock-intensive, if you can call it like that):

    guiElements = []
    temp=['redAll', 'greenAll', 'blueAll']
    guiElements.extend(temp)

    for i in range(6):
        temp1='red'+str(i)
        temp2='gre'+str(i)
        temp3='blu'+str(i)
        temp4='red'+str(i)+'Val'
        temp5='gre'+str(i)+'Val'
        temp6='blu'+str(i)+'Val'
        tempList=[temp1, temp2, temp3, temp4, temp5, temp6]
        guiElements.extend(tempList)

    def disableMainBoxGUI(self, status):
        #self.getGUIElements()
        for i in self.guiElements:
            self.ids[i].disabled = status

Is there a way to avoid freezing of the GUI? Do i have to add time.sleep(XX) or something?

Answer 1

Just some simple advice- learn to use threading. It's not that complicated and it will help a lot for running through long loops. I suggest reading this to familiarize yourself. Threading will speed up your applications and eliminate GUI freezing. I use a ThreadPoolExececutor in almost every one of my projects, but all you need is a simple daemon thread. Hope this helped!