在Tkinter中正确使用after（）

Question

我要执行的操作是运行另一个文件（文件1进程），并且在运行该文件时，我想检查本地目录中是否存在文件。 如果该文件不存在，那么一切都会继续运行，并在30秒后再次检查。 如果文件确实存在，我想将内容打印到标签上并停止file1进程。

我的下面代码使Tkinter擦除了所有标签并冻结了GUI，而发生了延迟。 我要去哪里错了？

def turnOn():
  global proc
  if proc is None:
    window.after(5000,file_chk) 
    print('Starting Beacon')
    proc = subprocess.Popen(["python3", "/home/pi/FLBeacon/FLBeaconout.py"])
    label1 = Label(window,text ="Beacon is Running")
    label1.configure(bg='green')
    label1.place(x= 350, y=10, width=150)
    global  label2
    label2 = Label(window,text = full_message)
    label2.configure(bg='green')
    label2.place(x=50, y=90, width=550)

def file_chk():    
    filelist = ['FLBeaconRecieved.txt']
    while True:
        list1 = []
        for file in filelist:
            list1.append(os.path.isfile(file))

        if all(list1):
           #all elements are true
           file = open("FLBeaconRecieved.txt")
           data = file.read()
           file.close()
           Results = Label(window, text = data)
           Results.place(x = 50, y = 350)
           print('Beacon Stopped')
           proc.terminate()
           proc = None
           label1 = Label(window,text = "Beacon is not running")
           label1.configure(bg='red')
           label1.place(x= 350, y=10, width=150)
           label2.destroy()
           break
        else:
          #time.sleep(30)
          print("there is no file")




on = Button(window, borderwidth=2, text = "Start Beacon", width=15, pady=5, command = turnOn)
off = Button(window, borderwidth=2, text = "Stop Beacon", width=15, pady=5, command = turnOff)
on.place(x=215,y=300)
 off.place(x=380,y=300)


def stop():
   window.destroy()
   #Top.destroy()

b = Button(window, borderwidth=2, text="Update Beacon", width=15, pady=5, command=enter)
b.place(x=50,y=300)
b = Button(window, borderwidth=2, text="Exit", width=12, pady=5, command = combine_funcs(turnOff, stop))
b.place(x=250,y=550)

window.mainloop()

Answer 1

与其在file_chk中使用循环来反复检查所需文件， file_chk使函数一次检查文件，并在文件尚未准备好时重新安排自身：

def file_chk():    
    # ... (note, there should be no "while True" loop any more)

    if all(list1):  # check the condition just once
        # ...
    else:
        window.after(30000, file_chk) # if it failed, reschedule yourself