Tcl_异步删除多线程Python错误

Question

我听说Python中的线程不容易处理，而且它们与tkinter的关系更加复杂。

我有以下问题。我有两个类，一个用于GUI，另一个用于无限进程（我必须同时使用这两个类）。首先，我启动GUI类，然后启动无限进程类。我希望当您关闭GUI时，它也会完成无限过程，程序也会结束。

代码的简化版本如下所示：

import time, threading
from tkinter import *
from tkinter import messagebox

class Interface(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)
        self.attrib1 = "Attrib from Interface class"

    def run(self): 
        #Main Window
        self.mainWindow = Tk()
        self.mainWindow.geometry("200x200")
        self.mainWindow.title("My GUI Title")
        self.mainWindow.protocol("WM_DELETE_WINDOW", self.quit)
        #Label
        lbCommand = Label(self.mainWindow, text="Hello world", font=("Courier New", 16)).place(x=20, y=20)
        #Start
        self.mainWindow.mainloop()

    #The Interface class contains methods that use attributes from itself and attributes from Process class.
    def method1(self): 
        print(self.attrib1)
        print(SecondThread.attrib2)

    def quit(self):
        if messagebox.askyesno('App','Are you sure you want to quit?'):
            #In order to use quit function, mainWindow MUST BE an attribute of Interface. 
            self.mainWindow.destroy()
            self.mainWindow.quit()  

class Process(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)
        self.attrib2 = "Attrib from Process class"

    def run(self):
        global finish
        while not finish:
            print("Proceso infinito")
            #Inside the infinite process a method from Interface class is used.
            GUI.method1()
            time.sleep(3)

finish = False  
#Starts the GUI
GUI = Interface()
GUI.start()
#Starts the infinity process
SecondThread = Process()
SecondThread.start()    
#Waits until GUI is closed
GUI.join()
print("When GUI is closed this message appears")
#When GUI is closed we set finish to True, so SecondThread will be closed.
finish = True
#After all the program should finish but it raises the error: Tcl_AsyncDelete: async handler deleted by the wrong thread

谢谢你的帮助！

Answer 1

我使用垃圾收集进行了粗略的修改。

import time, threading, gc
from tkinter import *
from tkinter import messagebox

class Interface(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)
        self.attrib1 = "Attrib from Interface class"

    def run(self):
        #Main Window
        self.mainWindow = Tk()
        self.mainWindow.geometry("200x200")
        self.mainWindow.title("My GUI Title")
        self.mainWindow.protocol("WM_DELETE_WINDOW", self.quit)
        #Label
        lbCommand = Label(self.mainWindow, text="Hello world", font=("Courier New", 16)).place(x=20, y=20)
        #Start
        self.mainWindow.mainloop()

    #The Interface class contains methods that use attributes from itself and attributes from Process class.
    def method1(self):
        print(self.attrib1)
        print(SecondThread.attrib2)

    def quit(self):
        global finish
        if messagebox.askyesno('App','Are you sure you want to quit?'):
            #In order to use quit function, mainWindow MUST BE an attribute of Interface.
            self.mainWindow.destroy()
            del self.mainWindow
            gc.collect()
            finish = True

class Process(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)
        self.attrib2 = "Attrib from Process class"

    def run(self):
        global finish
        while not finish:
            print("Proceso infinito")
            #Inside the infinite process a method from Interface class is used.
            GUI.method1()
            time.sleep(3)

finish = False
#Starts the GUI
GUI = Interface()
GUI.start()
#Starts the infinity process
SecondThread = Process()
SecondThread.start()
#Waits until GUI is closed
GUI.join()
#print("When GUI is closed this message appears")
#When GUI is closed we set finish to True, so SecondThread will be closed.
#finish = True

Answer 2

出现这种情况是因为您在线程上创建了Tk主窗口，而您没有在进程主线程上运行UI。退出进程时，将从进程主线程执行清理。对于您的示例，最简单的解决方案是在主线程（进程默认线程）上创建UI，并且仅使用另一个线程执行辅助任务。如果您的实际应用程序无法在主线程上创建UI，则需要研究从自己的线程终止Tk。删除Tcl解释器可能会为您做到这一点。

我修改了示例代码，以显示将UI保留在主线程上可以避免此错误消息。因为您希望在UI创建后但在运行之前创建辅助角色，所以一旦Tk主循环运行，我们可以使用Tk后方法启动辅助角色。

import time, threading
from tkinter import *
from tkinter import messagebox

class Interface:
    def __init__(self):
        #threading.Thread.__init__(self)
        self.attrib1 = "Attrib from Interface class"
        #Main Window
        self.mainWindow = Tk()
        self.mainWindow.geometry("200x200")
        self.mainWindow.title("My GUI Title")
        self.mainWindow.protocol("WM_DELETE_WINDOW", self.quit)
        #Label
        lbCommand = Label(self.mainWindow, text="Hello world", font=("Courier New", 16)).place(x=20, y=20)

    #def run(self): 

    def start(self): #Start
        self.mainWindow.mainloop()

    #The Interface class contains methods that use attributes from itself and attributes from Process class.
    def method1(self): 
        print(self.attrib1)
        print(SecondThread.attrib2)

    def quit(self):
        if messagebox.askyesno('App','Are you sure you want to quit?'):
            #In order to use quit function, mainWindow MUST BE an attribute of Interface. 
            self.mainWindow.destroy()
            self.mainWindow.quit()  

class Process(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)
        self.attrib2 = "Attrib from Process class"

    def run(self):
        global finish
        while not finish:
            print("Proceso infinito")
            #Inside the infinite process a method from Interface class is used.
            GUI.method1()
            time.sleep(3)

finish = False
#Starts the GUI

GUI = Interface()
#Starts the infinity process
SecondThread = Process()
GUI.mainWindow.after(50, SecondThread.start)   
#Waits until GUI is closed
GUI.start()
#GUI.join()
print("When GUI is closed this message appears")
#When GUI is closed we set finish to True, so SecondThread will be closed.
finish = True
#After all the program should finish but it raises the error: Tcl_AsyncDelete: async handler deleted by the wrong thread