On 2021-02-26 23:59, John O'Hagan wrote:
> On Fri, 26 Feb 2021 08:19:14 +0100
> Christian Gollwitzer <aurio...@gmx.de> wrote:
>
>> Am 26.02.21 um 06:15 schrieb John O'Hagan:
> [...]
>> >
>> > I've followed your suggestions as per my last post, and can
>> > confirm the same freezing behaviour when running your code
>> > directly as a tclsh script on Debian Testing, Tcl 8.6.11.
>>
>> You might report this as a bug to the Tcl bugtracker
>> https://core.tcl-lang.org/tk/ticket
>>
>> I guess the problem is with the steady creation of widgets. Tk was
>> not meant to be used like that. Tkinter creates new widget names
>> for each widget with random numbers, just like the Tcl code above
>> does, whereas in a usual Tcl/Tk program the names are given by the
>> programmer.
>
> Thanks, I will make the bug report. However, based on your comments
> above, it looks similar to this one, closed as invalid 16 years ago:
>
> https://core.tcl-lang.org/tk/tktview/1173484fffffffffffff
>
> This was also related to memory "creep" caused by Tk's cache of
> names, which AIUI is a Tk design feature (but I don't know Tk!).
>
>> Can you also check this program, which reuses the same widget path
>> name, albeit does the creation/destruction in cycles:
>>
>> ======================
>> package require Tk
>>
>> proc randint {} {
>> expr {int(rand()*10000000)}
>> }
>>
>> proc display {label} {
>> destroy $label
>> set label [label .l -text [randint]]
>> pack $label
>> after 100 [list display $label]
>> }
>>
>> display [label .l]
>> ========================
>>
>
> I have tried this overnight and it is still running, not frozen and
> with no apparent increase in memory use. I guess that is likely the
> issue. I don't know Tcl/Tk - is there a way to emulate the above
> approach of re-using the widget name in tkinter?
>
>> As mentioned by others, typically you wouldn't continuously
>> recreate new widgets, but either update the text of the widget
>> (label['text']="New text") or attaching a StringVar() )
>>
>> or, if you must rearrange the widgets, you pack_forget() them and
>> then repack them.
>>
>> Christian
>
> This is possible of course, but will require more than a repack. In
> my use case, each widget is an attribute of a Python object,
> intended control and display data about that object, and there is an
> indeterminate number of such objects at any given time. I had
> assumed I could just destroy the widget and let the object go out of
> scope to be garbage collected. I'll need to redesign this
> altogether if I can't rely on Tk to manage memory.
>
> IMHO it's quite surprising if .destroy doesn't free all the
> resources used by a widget!
>
I've look in Lib\tkinter\__init__.py and it appears that you can give
it a name, so:
from tkinter import *
from random import randint
root = Tk()
def display(label):
label.destroy()
label = Label(name='my_label', text=randint(0, 9))
label.pack()
root.after(1, display, label)
display(Label(name='my_label'))
mainloop()
When I do that I'm not seeing a memory rise.
