On 2025-06-10 09:39, John O'Hagan wrote:
Hi list
I noticed this issue with a long-running application that displays
information from a variable number of sources by opening an embedded
window on a Text widget for each new source, and closing it when the
source is completed. To prevent increasing memory use, the widgets
inside the windows are "recycled", i.e. hidden using a tag and cached
when the window is closed, to be re-used when needed. New widgets are
only created when the cache is empty.
The code below demonstrates the issue by rapidly creating and hiding a
window containing the same Label widget. On my machine, each
create_window call initially takes < 1 ms, but a few minutes later
increases to several ms. After several hours, it takes a few seconds
for each operation.
If the commented line removing the tag is used instead of the
window_create call, there is no slowdown. Unfortunately this is not
useful in the real program, which requires that new windows open in a
specified position. AFAIK there is no way to move an embedded window on
a Text widget other than by re-calling window_create (but I'd be glad
to be wrong about that).
Any insights or suggestions?
-------------------------------
from time import time
from tkinter import *
root = Tk()
button = Button(root, text='Run')
text = Text(root)
text.tag_config('hide', elide=True)
label=Label(text, text='running')
def show_and_hide():
if button['text']=='Stop':
if text.tag_names(label):
t = time()
#this line gradually gets slower:
text.window_create(END, window=label)
#this line doesn't:
#text.tag_remove('hide', label)
print(round((time() - t) * 1000))
else:
text.tag_add('hide', label)
button.after(10, show_and_hide)
def run():
if button['text']=='Run':
button['text'] = 'Stop'
text.window_create(END, window=label)
show_and_hide()
else:
button['text'] = 'Run'
text.tag_add('hide', label)
button['command'] = run
button.pack()
text.pack()
mainloop()
If you look at the memory usage, you'll see that it rises.
I think that's because 'window_create' adds the label each time, so the
number of them (well, references to the single label, to be exact) in
the text widget increases.
It's interesting that listing them with 'window_names' shows only 1,
perhaps because they are all the same label and therefore have the same
name. Strange though.
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