Tkinter long-running window freezes

[Christian Gollwitzer]

Am 24.02.21 um 12:35 schrieb John O'Hagan:
> Hi list
> 
> I have a 3.9 tkinter interface that displays data from an arbitrary
> number of threads, each of which runs for an arbitrary period of time.
> A frame opens in the root window when each thread starts and closes
> when it stops. Widgets in the frame and the root window control the
> thread and how the data is displayed.
> 
> This works well for several hours, but over time the root window
> becomes unresponsive and eventually freezes and goes grey. No error
> messages are produced in the terminal.
> 
> Here is some minimal, non-threaded code that reproduces the problem on
> my system (Xfce4 on Debian testing):
> 
> from tkinter import *
> from random import randint
> 
> root = Tk()
> 
> def display(label):
>      label.destroy()
>      label = Label(text=randint(0, 9))
>      label.pack()
>      root.after(100, display, label)
> 
> display(Label())
> mainloop()
>   
> This opens a tiny window that displays a random digit on a new label
> every .1 second. (Obviously I could do this by updating the text rather
> than recreating the label, but my real application has to destroy
> widgets and create new ones).
> 
> This works for 3-4 hours, but eventually the window freezes.


I think it is not yet clear, if this is a bug in Tkinter or in Tcl/Tk, 
the underlying scripting language. It might also be platform dependent. 
Are you on Windows? Here is an equivalent Tcl program:

======================
package require Tk

proc randint {} {
	expr {int(rand()*10000000)}
}

proc display {label} {
	destroy $label
	set id [randint]
	set label [label .l$id -text [randint]]
	pack $label
	after 100 [list display $label]
}

display [label .l]
========================


Can you run this and check that the freeze also occurs? If you can't 
execute the Tcl that is used by Python directly, you may also do 
something like


root = Tk()
root.eval('Here comes the Tcl code')
root.mainloop()

Can you also find out what version of Tcl/Tk you are using? Try

root.eval('info patchlevel')

	Christian