每当我单击重新启动按钮更新notification1（标签）的文本时

from tkinter import *
import tkinter as tk
from multiprocessing import Process

def notify(text):
    notify_heading_text.set(f"App : {text}")
    
    
def on_restart():
    notify("This text will be updated")
    t1 = Process(target=print_hi)
    t1.daemon = True
    t1.start()
    
    
def print_hi():
    notify("Hi There")


if __name__ == '__main__':
    root = Tk()
    root.geometry('400x400')
    root.resizable(0, 0)
    global notify_heading_text
    notify_heading_text = tk.StringVar()

    notification1 = Label(height=1, textvariable=notify_heading_text, bd=0)
    notification1.pack(fill=X, side=TOP)
    notification1.configure(bg='white', fg='black', font=('Helvetica', 12, 'bold'), pady=10)
    bind3 = tk.StringVar()
    b3 = Button(root, borderwidth=0, fg="white", activebackground='#40556a', activeforeground='white', bg="black",
                textvariable=bind3, command=on_restart, font=('Helvetica', 12, 'bold'), padx=10, pady=6)
    bind3.set('Restart')
    b3.pack(side=RIGHT)

    root.mainloop()

我收到此错误

Process Process-1:
Traceback (most recent call last):
  File "C:\Users\prana\AppData\Local\Programs\Python\Python39\lib\multiprocessing\process.py", line 315, in _bootstrap
    self.run()
  File "C:\Users\prana\AppData\Local\Programs\Python\Python39\lib\multiprocessing\process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\prana\PycharmProjects\tkinter\main.py", line 18, in print_hi
    notify("Hi There")
  File "C:\Users\prana\PycharmProjects\tkinter\main.py", line 7, in notify
    notify_heading_text.set(f"App : {text}")
NameError: name 'notify_heading_text' is not defined

**on_restart（）方法中的notify("This text will be updated")工作正常并更新文本，但print_hi（）**方法中的相同方法不更新Tkinter窗口的文本，称'notify_heading_text'未定义，尽管它被声明为全局变量。由于某些原因，我无法使用root.after()，它更新Tkinter窗口的显示时没有错误，工作正常，但我想线程化。