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How to use multi-threading to play/pause BG Music in tkinter app?

A part of what I am doing, needs me to have background music in a tkinter game I created long time ago. I am using playsound.playsound{ Docs Here } to play music . I could use any other tool if needed to achieve what I intend like pyglet.media or pygame.mixer.
As the actual program was about 1k lines, I have tried adding an MCVE below.
Desired behavior & issue
The BGM (Background Music) should start when the app is launched - of course alongside a GUI, I would have a button to stop the BGM OR more preferably pause/play - I do think I need to use anything other than playsound.playsound for pause/play behavior.
The issue:: I can't seem to figure out how to make that communication between both the threads so that I can stop the music from playing or perhaps terminate the thread playing BGM - I could create a new thread when needed.
What I Have Tried
First up, I created two classes for GUI and BGM, each inheriting from threading.Thread - overridden the constructor and run() methods to do what I intend. Like this -
import tkinter as tk
import threading
from playsound import playsound
class BGM(threading.Thread):
def __init__(self, stopSignal):
threading.Thread.__init__(self)
self.stopSignal = stopSignal
def run(self):
while not self.stopSignal:
playsound('LoL.mp3') # to make this function play asynchronously, pass in False as second arg.
class GUI(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
self.root = tk.Tk()
def run(self):
tk.Button(self.root, text='stop').pack()
if __name__ == '__main__':
guiThread = GUI()
guiThread.start()
musicThread = BGM(0)
musicThread.start()
guiThread.root.mainloop()
But as you can see, it will just continue to play the song infinitely as long as the app is alive. There is no communication ( or active sync ) between GUI ( the button to stop song ) and BGM thread.
Now I tried using threading.Event() objects. The official docs on threading.Event() quotes:
This is one of the simplest mechanisms for communication between
threads: one thread signals an event and other threads wait for it.
An event object manages an internal flag that can be set to true with
the set() method and reset to false with the clear() method. The
wait() method blocks until the flag is true.
I'm not sure if this is useful for me to achieve what I intend but using threading.Event() did not do anything for me (or maybe I wasn't able to make use of it properly)
Now
What would you suggest to do to implement a BGM thread which can be stopped ( or paused/played preferably ) with a button(s) in the GUI thread.
Thank You For Any help Or Suggestions :)

Python - Run next thread when the previous one is finished

I'm writing a tkinter app.
I want to use Thread to avoid the tkinter window freezing but actually I did not find solution.
A quick part of my code (simplify):
from threading import Thread
import tkinter as tk
class App(tk.Tk):
def __init__(self):
super().__init__()
search_button = tk.Button(self, text='Print', command=self.Running)
search_button.grid(row=0, column=0)
def funct1(self):
print('One')
def funct2(self):
print('Two')
def CreateThread(self, item):
self.item = item
t = Thread(target=self.item)
t.start()
def Running(self):
self.CreateThread(self.funct1)
# How to wait for the end of self.CreateThread(self.funct1) ?
self.CreateThread(self.funct2)
if __name__ == '__main__':
myGUI = App()
myGUI.mainloop()
How to wait for the self.CreateThread(self.funct1) ending before running self.CreateThread(self.funct2).
With a queue ?
With something else ?
I already have take a look to Thread.join() but it freez the tkinter window.
Hope you can help me :)

IMO you should think differently about what "Thread" means. A thread is not a thing that you run. A thread is a thing that runs your code. You have two tasks (i.e., things that need to be done), and you want those tasks to be performed sequentially (i.e., one after the other).
The best way to do things sequentially is to do them in the same thread. Instead of creating two separate threads, why not create a single thread that first calls funct1() and then calls funct2()?
def thread_main(self):
funct1()
funct2()
def Running(self):
Threead(target=self.thread_main).start()
P.S.: This could be a mistake:
def CreateThread(self, item):
self.item = item
t = Thread(target=self.item)
t.start()
The problem is, both of the threads are going to assign and use the same self.item attribute, and the value that is written by the first thread may be over-written by the second thread before the first thread gets to used it. Why not simply do this?
def CreateThread(self, item):
Thread(target=item).start()
Or, since the function body reduces to a single line that obviously creates and starts a thread, why even bother to define CreateThread(...) at all?

You can synchronize threads using locks. Hard to give a concrete answer without knowing what needs to be done with these threads. But, locks will probably solve your problem. Here's an article on synchronizing threads.

Tcl_AsyncDelete Error. Unable to terminate Tk

I am using Tkinter in a ROS node to create a GUI and publish the scale values to another ROS Node. I have accomplished this. The problem comes when I try to close this GUI and rerun the node. The log message that I get is as follows:
Exception RuntimeError: 'main thread is not in main loop' in <bound method DoubleVar.__del__ of <Tkinter.DoubleVar instance at 0x7f19ea0c3ab8>> ignored
Tcl_AsyncDelete: async handler deleted by the wrong thread
Aborted (core dumped)
According to this, I think I will have to terminate Tk from its own thread. But I do not know how to do this. My code is as follows:
#!/usr/bin/env python
import rospy
from std_msgs.msg import Float64MultiArray
from Tkinter import *
from calibration_camera_lidar.msg import Euler_val
import tkMessageBox
class slider():
def __init__(self):
rospy.loginfo("init")
rospy.init_node('slider', anonymous=True, disable_signals=True)
self.spub = rospy.Publisher('Slider_values', Euler_val, queue_size=10)
self.final_ev = Euler_val()
self.listener()
def listener(self):
rospy.Subscriber("Euler_values", Float64MultiArray, self.callback)
rospy.spin()
def callback(self, data):
self.eulerval = list(data.data)
self.final_ev.Euler_angles = [self.eulerval[0], self.eulerval[1], self.eulerval[2]]
self.spub.publish(self.final_ev)
rospy.loginfo(self.final_ev)
self.slider_value()
def callback_exit(self):
if tkMessageBox.askokcancel("Quit", "Do you really wish to quit?"):
self.root.destroy()
self.root.quit()
rospy.signal_shutdown("shutdown")
def slider_value(self):
self.root = Tk()
self.root.title("fine tune")
self.root.protocol("WM_DELETE_WINDOW", self.callback_exit)
self.y_var = DoubleVar()
self.y_scale = Scale( self.root, from_=self.eulerval[0]-1, to=self.eulerval[0]+1, length=300, label="yaw", resolution=0.0000000000001, variable = self.y_var, orient=HORIZONTAL, command=self.pub_y)
self.y_scale.set(self.eulerval[0])
self.y_scale.pack(anchor=CENTER)
self.label = Label(self.root)
self.label.pack()
self.root.mainloop()
def pub_y(self, val_y):
self.eulerval[0] = float(self.y_scale.get())
self.final_ev.Euler_angles = [self.eulerval[0], self.eulerval[1], self.eulerval[2]]
self.spub.publish(self.final_ev)
rospy.loginfo(self.final_ev)
if __name__ == '__main__':
try:
slider()
except:
rospy.loginfo("Node terminated.")
I would be grateful if you could help. Thanks!

The problem is that rospy is internally multithreaded yet Tk is very keen on only being used from a single thread. (Technically, it's possible to use Tk from multiple threads — by appropriate quarantining of window objects and so on — but it's really tricky to get right and you probably don't want that.)
The easiest approach in general is to make two classes, one that just handles Tk (with incoming and outgoing messages all queued) and the other which does the bridging into the rest of the code. Then, when you want the Tk GUI to appear you run a thread that just does that and then talk to that thread just by its queues. Which sounds like a lot more work, but you can't defeat Tk's internal awareness of threads other than by keeping it strictly on one thread.
However, it might be enough to change the shutdown sequence a bit to be like this.
def callback_exit(self):
if tkMessageBox.askokcancel("Quit", "Do you really wish to quit?"):
self.root.destroy()
rospy.signal_shutdown("shutdown")
sys.exit(0)
Assuming that you're in the correct thread. If not, you'll need a direct os._exit(0) instead and that's considered dangerous for good reason (yet it might be necessary).

Infinite loops in Python threads

So I have two python threads running from inside a class. I have checked using
threading.active_count()
and it says both threads are running. The first thread includes a tkinter window which works fine. The second thread I am using as an event manager for the first window, which also works okay by itself. However, when I run the second thread alongside the first thread, the first thread does not work, ie. the window does not appear. This is even if the first thread is executed first. When I remove the infinite loop from the second thread, the first thread works again, can anyone explain this to me? Here is the class:
class Quiz(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
def show(self, question):
self.question = quiz[question][0]
self.correct = quiz[question][1]
self.incorrectA = quiz[question][2]
self.incorrectB = quiz[question][3]
self.ref = quiz[question][4]
questionDisplay.config(text=self.question)
correctButton = "answer" + str(self.ref[0])
eval(correctButton).config(text=self.correct, command=lambda : check(True))
incorrect1 = "answer" + str(self.ref[1])
eval(incorrect1).config(text=self.incorrectA, command= lambda : check(False))
incorrect2 = "answer" + str(self.ref[2])
eval(incorrect2).config(text=self.incorrectB, command= lambda : check(False))
return self.correct
def run(self):
print("thread started")
print(threading.active_count())
while True:
print(questionQueue.qsize())
if questionQueue.qsize() >= 1:
pass
else:
pass
print("looped")
Thanks

From the code as currently shown it is not obvious where the problem lies. But keep the following in mind;
Tk is event-driven like basically all GUI toolkits. So for the GUI to work you need to run Tk's mainloop. The only pieces of your code that it runs in the main loop are the various callbacks attached to things like buttons, menus and timers.
Like most GUI toolkits Tk isn't thread-safe because of the overhead that would require. To keep it working properly, you should only call Tk functions and methods from one thread.
Python's threads are operating system threads. This means they are subject to operating system scheduling. And the OS sometimes gives more time to threads that are busy. So if a thread that is spinning in a busy-loop is pre-empted (as is done regularly), chances are that it ends up being run again instead of the GUI thread.

Using Python Tk as a front-end for threaded code

I know that Python’s Tk interface has some problems when using threads, and I’ve already run into problems with it. My idea is now to use a Queue.Queue to somehow pass events to the Tk mainloop, similarly to the following example.
from Tkinter import *
import Queue
import time
# this queue will be filled by other threads
queue = Queue.Queue()
queue.put("Helloooo!")
queue.put("hi there, everyone!")
class Application(Frame):
def update(self):
while True:
try:
text = queue.get(False)
self.hi_there["text"] = text
time.sleep(3)
except Queue.Empty:
self.quit()
def create_widgets(self):
self.hi_there = Label(self)
self.hi_there["text"] = "Hello"
self.hi_there.pack({"side": "left"})
def __init__(self, master=None):
Frame.__init__(self, master)
self.pack()
self.create_widgets()
root = Tk()
app = Application(master=root)
app.update()
app.mainloop()
Of course, I must not call update myself (this will execute everything before the UI is even shown) but need Tk to handle that during its mainloop.
Is there any foolproof way to accomplish that with Tk which will not break under certain circumstances? Or should I just resort to Qt for that?

As a general rule of thumb a GUI application should never, ever call sleep, should never have an infinite loop (except for the event loop), and you should never call 'update'. The only exception to never calling update is that is is ok only when you truly understand why you should not.
Create a method that does two things: check the queue, and then use 'after' to call itself after some small period of time. Then, call this method once at the beginning of your program just before starting the event loop, after all other initialization has taken place.
For a working example of such a function, see How to create a timer using tkinter?