Not sure I'm running a thread properly

Question

I am running a thread to constantly monitor temperature, and update a global variable that other functions call upon to perform their tasks accordingly. Everything works now, and I could live with it. But I wanted to reach out and see if anyone has a smarter way to keep this going until the mainloop ends. Here is how the thread is started...

thread1 = Thread(target = test)
try:
    thread1.start()
except (KeyboardInterrupt, SystemExit):
    thread1.stop()
    sys.exit()

I guess I could make a small script just to let it run. Sorry...

import time
import tkinter
from tkinter import *
from threading import Thread

root = Tk()

timer = True

global counter
counter = 0
var1 = StringVar()
var1.set(counter)

def test():
    global counter
    while timer:
        counter += 1
        var1.set(counter)
        root.update
        time.sleep(1)

testtext = Label(root,textvariable=var1,font='Consolas 24 bold')
testtext.grid(row=1,column=1,sticky="N,S,E,W",padx=10,pady=0)
testtext2 = Label(root,text="SECONDS",font='Consolas 18 bold')
testtext2.grid(row=2,column=1,sticky="N,S,E,W",padx=10,pady=0)

thread1 = Thread(target = test)
try:
    thread1.start()
except (KeyboardInterrupt, SystemExit):
    thread1.stop()
    sys.exit()

root.mainloop()

As you will see, after you close the window, the thread does end, but not very cleanly.

Any ideas?

score 1 · Answer 1 · answered Feb 07 '19 at 17:07

Tkinter supports protocol handlers.

The most commonly used protocol is called WM_DELETE_WINDOW, and is used to define what happens when the user explicitly closes a window using the window manager.

import time
import tkinter
from tkinter import *
from threading import Thread

def on_closing():
    thread1.close()
    root.destroy()

def test():
    global counter
    while timer:
        counter += 1
        var1.set(counter)
        root.update
        time.sleep(1)

root = Tk()

timer = True

global counter
counter = 0
var1 = StringVar()
var1.set(counter)

testtext = Label(root,textvariable=var1,font='Consolas 24 bold')
testtext.grid(row=1,column=1,sticky="N,S,E,W",padx=10,pady=0)
testtext2 = Label(root,text="SECONDS",font='Consolas 18 bold')
testtext2.grid(row=2,column=1,sticky="N,S,E,W",padx=10,pady=0)

global thread1 = Thread(target = test)
try:
    thread1.start()
except (KeyboardInterrupt, SystemExit):
    thread1.stop()
    sys.exit()

root.protocol("WM_DELETE_WINDOW", on_closing)
root.mainloop()

Basically, the program listens to the close event and decides what to do as the window is killed in the functuon on_closing().

Bruh, what a waste of time. Good luck. – Daniel Reyhanian Feb 07 '19 at 17:38 — Daniel Reyhanian, Feb 07 '19 at 17:38
os._exit(1) Thank you @Daniel Reyhanian for all the help! – FatherPhipps Feb 07 '19 at 18:11 — FatherPhipps, Feb 07 '19 at 18:11

score 1 · Answer 2 · answered Feb 07 '19 at 18:09

1

Got it. Thank you Daniel Reyhanian for pointing me toward the

root.protocol("WM_DELETE_WINDOW", on_closing)

thing. Never seen that before.

Here is the final bit using: os._exit(1)

import os
import time
import tkinter
from tkinter import *
from threading import Thread

root = Tk()

timer = True

global counter
counter = 0
var1 = StringVar()
var1.set(counter)

def on_closing():
    os._exit(1)

def test():
    global counter
    while timer:
        counter += 1
        var1.set(counter)
        root.update
        time.sleep(1)

testtext = Label(root,textvariable=var1,font='Consolas 24 bold')
testtext.grid(row=1,column=1,sticky="N,S,E,W",padx=10,pady=0)
testtext2 = Label(root,text="SECONDS",font='Consolas 18 bold')
testtext2.grid(row=2,column=1,sticky="N,S,E,W",padx=10,pady=0)

thread1 = Thread(target = test)
thread1.start()

root.protocol("WM_DELETE_WINDOW", on_closing)
root.mainloop()

answered Feb 07 '19 at 18:09

FatherPhipps

39
6

Glad to hear so, apparently it wasn't a total waste of time. Keep it up! – Daniel Reyhanian Feb 07 '19 at 18:12
Would be much nicer if you could add an explanation about os._exit(1) – Daniel Reyhanian Feb 07 '19 at 18:13
[https://docs.python.org/3.4/library/os.html?highlight=os%20_exit#os._exit] It seems like it basically smashes any and all and doesn't care to even look for errors to report them. – FatherPhipps Feb 07 '19 at 18:19
I haven't tested this on the device it's intended for (RaspberryPi) But on windows, I can't find any evidence of any left over processes floating in the system. If it does in fact leave it in limbo then yes we have an issue, but if not, then this is exactly what I'm wanting. I will update you in the morning. – FatherPhipps Feb 07 '19 at 19:15
Plus explain what is limbo in the morning ;) GN! – Daniel Reyhanian Feb 07 '19 at 19:23
And how can u actually run stuff on RaspberryPi? How it works?? – Daniel Reyhanian Feb 07 '19 at 19:25
Limbo? Guess it's my way of saying in the background. And I couldn't wait. The processes do in fact die. – FatherPhipps Feb 07 '19 at 19:48
I was talking about the Raspberry thing. It's a good thing then isn't it? – Daniel Reyhanian Feb 07 '19 at 19:52
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/188076/discussion-between-fatherphipps-and-daniel-reyhanian). – FatherPhipps Feb 07 '19 at 19:58

Not sure I'm running a thread properly

2 Answers2