Addictive points when displaying logs with Tk.text

at first

I found an unexpected trap when I was investigating a memory leak problem at work, so I will post it. I think it will be a bit random, but please forgive me.

environment

OS:Windows10

Anaconda PowerShell Prompt

(base) PS C:\Users\95315> python -V
Python 3.6.10 :: Anaconda, Inc.
(base) PS C:\Users\95315> conda -V
conda 4.9.2
(base) PS C:\Users\95315>conda list
…
tk                        8.6.8                hfa6e2cd_0
…

What i wanted to do

https://tkdocs.com/tutorial/text.html I'd like you to refer to the Example: Logging Window section on the above page, but I made a program that pulls the contents of the logger and displays it in Tk.text. The point is the code below.

python

from tkinter import *
from tkinter import ttk

root = Tk()
log = Text(root, state='disabled', width=80, height=24, wrap='none')
log.grid()

def writeToLog(msg):
    numlines = int(log.index('end - 1 line').split('.')[0])
    log['state'] = 'normal'
    if numlines==24:
        log.delete(1.0, 2.0)
    if log.index('end-1c')!='1.0':
        log.insert('end', '\n')
    log.insert('end', msg)
    log['state'] = 'disabled'

What happened

I deleted it from my head when the number of lines displayed by the logger exceeded a certain number, but even so, the memory consumption increased and eventually it fell due to lack of memory for each PC, which is a headache problem. Was out ...

What was wrong

When I searched for various things, the following reference described the cause of the slightly old one. https://anzeljg.github.io/rin2/book2/2405/docs/tkinter/text-undo-stack.html

The Text widget has a built-in mechanism that allows you to implement undo and redo operations that can cancel or >reinstate changes to the text within the widget.

In short, Tk.text has an optional undo/redo stack. It's convenient. Yeah. I wish I hadn't turned it on and behaved like an unlimited number of stacks.

So how did you fix it

All you have to do is disable the stack. In the code I mentioned earlier, I'll fix it.

python

from tkinter import *
from tkinter import ttk

root = Tk()
log = Text(root, state='disabled', width=80, height=24, wrap='none',undo=False)
log.grid()

def writeToLog(msg):
    numlines = int(log.index('end - 1 line').split('.')[0])
    log['state'] = 'normal'
    if numlines==24:
        log.delete(1.0, 2.0)
    if log.index('end-1c')!='1.0':
        log.insert('end', '\n')
    log.insert('end', msg)
    log['state'] = 'disabled'

Just add undo = False. ~~ How much time do I have for this party ... ~~ Well, it was a rather nasty story, so let's write it in the article. ~~ Otherwise, drinking will not go down. ~~ That's why I wrote an article.

At the end

Even TKDocs, which is linked from the official, has this kind of thing, so what can I trust anymore ... For the time being, I thought it was important to explore various things, not just one source. So Tkinter doesn't mean shit or anything like that. I mean, there are various GUIs in Python, and I think it's okay to use Tkinter, which is provided as standard. If you are worried that some of these troubles are buried, you may consider using a good library. After that, I think it's okay to write in Qiita's article that there was such a trouble with collective intelligence. When I have a hard trouble, I feel a little refreshed if I think that I have made a story to write on Qiita. ~~ So it's a scary story from here, but there is still one more memory leak factor left and I have to find and crush it too ... Well, I don't think there are many people who get caught, so I hope you can think that there is such a thing as a reading material. Thank you for reading this far.