kivy multiprocessing, je ne comprend pas comment sa marche

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.tabbedpanel import TabbedPanel
from kivy.uix.tabbedpanel import TabbedPanelItem
from kivy.clock import Clock
from functools import partial

import multiprocessing


def worker():
    print('calculator')
    x = 2
    Clock.schedule_interval(partial(func, x), 1)


def func(x, dt):
    print("x={0}, dt={1}".format(x, dt))
    x * x
    print("x * x = {}".format(x * x))


class MyApp(App):
    # layout
    def build(self):
        layout = BoxLayout(orientation='vertical')

        tab=TabbedPanel(do_default_tab=False)
        self.tabitem1=TabbedPanelItem(text='tab1')
        self.tabitem2=TabbedPanelItem(text='tab2')
        self.tabitem3=TabbedPanelItem(text='tab3')
        tab.add_widget(self.tabitem1)
        tab.add_widget(self.tabitem2)
        tab.add_widget(self.tabitem3)
        layout.add_widget(tab)

        #load tab in other core cpu ?
        #self.tab1()

        p = multiprocessing.Process(target=self.tab1())
        p.start()

        p2 = multiprocessing.Process(target=worker())
        p2.start()

        return layout

    def tab1(self):
        layout1 = BoxLayout(orientation='vertical')

        btn = Button(text='btn1', font_size=24)
        btn.bind(on_press=self.click_button)
        layout1.add_widget(btn)

        btn2 = Button(text='btn2', font_size=24)
        btn2.bind(on_press=self.click_button)
        layout1.add_widget(btn2)

        self.tabitem1.add_widget(layout1)

    def click_button(self, btn):
        print(btn.text)


if __name__ == "__main__":
    MyApp().run()