threaded_decorator.py

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import StringProperty
from kivy.clock import mainthread

import threading
import time

def threaded(callback):
    def wrapper(*args):
        thread = threading.Thread(target=callback, args=args)
        thread.start()
        return thread
    return wrapper


class MyBL(BoxLayout):
    counter = 0
    data_label = StringProperty("Nothing yet!")

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.get_data()

    @threaded
    def get_data(self):
        while App.get_running_app().running:
            # get data here
            # sock.recv(1024) or how you do it
            time.sleep(1)

            # if you change the UI you need to do it on main thread
            self.set_data_label(self.counter)

            self.counter += 1

    @mainthread
    def set_data_label(self, data):
        self.data_label = str(data)

KV = """
MyBL:
    Label:
        font_size: "30sp"
        text: "Some Data"
    Label:
        font_size: "30sp"
        text: root.data_label
"""


class MyApp(App):
    running = True

    def build(self):
        return Builder.load_string(KV)

    def on_stop(self):
        self.running = False

MyApp().run()