Problem wiht Kivy + MS Windows + multi processing - extra window popping up

[Brent Picasso]

Hello,

I am experiencing a fundamental problem with Kivy and multi-processing on windows.  (1.8.0  / Python 2.7).  When I run the code below, i'm seeing an kivy window pop up when the sub-process is created. From my research, it seems to be tied to kivy being referenced before the sub process is created. The example to repro is is simple, listed below:

What can I do to use multiprocessing successfully with kivy?

Thank you very much.

========File mptest.py==============

from time import sleep

import multiprocessing

   

def the_sub_process():

    for x in range(0,10):

        print("sub process")

        sleep(1)

class Mptest(object):

    def __init__(self, **kwargs):

        self.start_connection_process()

        

    def start_connection_process(self):

        connection_process = multiprocessing.Process(target=the_sub_process)

        connection_process.start()

========File main.py==============

#!/usr/bin/python

__version__ = "1.0.0"

from multiprocessing import freeze_support

from mptest import Mptest

if __name__ == '__main__':

    freeze_support()

    Mptest().start_connection_process()

from kivy.uix.label import Label

#as soon as this reference to a kivy widget is enabled, multiple windows open up.

Label()

[Brent Picasso]

I think I'm getting further. Seems that my app somewhere has some kivy code not being guarded by the if __name__ == '__main__'

this example works, with only one window.

#!/usr/bin/python

__version__ = "1.0.0"

from multiprocessing import freeze_support

from mptest import Mptest

import kivy

kivy.require('1.8.0')

from kivy.app import App

from kivy.uix.button import Button

class MyApp(App):

    def build(self):

        return Button(text='Hello World')

if __name__ == '__main__':

    freeze_support()

    Mptest().start_connection_process()

    MyApp().run()

[Brent Picasso]

So I have liberal use of Builder.load_file() which I believe is triggering this problem.  For example, the snippet below.

Where would an appropriate place be for loading this file - and making sure it's executed only once?

Thanks, 

Brent

=============================

Builder.load_file('iconbutton.kv')

class IconButton(Button):

    def __init__(self, **kwargs):

        super(IconButton, self).__init__(**kwargs)

class RoundedRect(BoxLayout):

    rect_color = ObjectProperty((0.5, 0.5, 0.5, 0.8))

    corners = ListProperty([0, 0, 0, 0])

    line_width = NumericProperty(1)

    resolution = NumericProperty(100)

=============================

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Brent Picasso

Autosport Labs

Technology for Race and Street

[Brent Picasso]

Fixed. I put all of the imports in my main.py in a guard block.