Memory leak in Tkinter?????

klappnase klappnase at
Sun Jul 25 02:01:12 CEST 2004

elbertlev at (Elbert Lev) wrote in message news:<9418be08.0407231106.42f0bdde at>...
> #When I'm running this script on my windows NT4.0 box, 
> #every time dialog box is reopened there is memory growth 384K.
> #Bellow is the text I sent to Stephen Ferg (author of easygui) 
> # I have tested the pure Tkinter, 
> # by modifiing on of the examples in the distribution.
> # This little guy also exibits the same behaviour. 
> # Namely: every time the window is closed and reoppend,
> # there is memory leak of several hundreds 384K
> # (good number??? 256 + 128??? or it's windows?)
> # del root does not help at all.
> # Anyway, I don't think that this leak is in easygui. 
> # The leak (if any is in TKinter (or it's windows implementation).
> # I'm not runnin linux in my shop, so I will ask my friends to tes it on linux,
> # will keep you posted.

I don't see a memory leak here on my linux box; there's a noticeable
increase of memory use if I close/reopen the window a few times within
a couple of seconds, but after about 5 seconds it disappears, so it
looks like python's garbage collection works properly (are you aware
that calling "del" does not free the memory immediately but just
remove the reference to the deleted object so it can be garbage
collected later on).

> from Tkinter import *
> import string 
> # This program  shows how to use a simple type-in box

I'm not sure what you want to do with this program, looks rather like
a useless type-in box to me.

> class App(Frame):
>     def __init__(self, master=None):
>         Frame.__init__(self, master)
>         self.pack()
>         self.entrythingy = Entry()
>         self.entrythingy.pack()
>         # and here we get a callback when the user hits return. we could
>         # make the key that triggers the callback anything we wanted to.
>         # other typical options might be <Key-Tab> or <Key> (for anything)
>         self.entrythingy.bind('<Key-Return>', self.print_contents)
>     def print_contents(self, event):
>         print "hi. contents of entry is now ---->", self.entrythingy.get()
> while 1:
>     root = App()
>     root.master.title("Foo")
>     root.mainloop()
>     del root

Why do you use the "while 1" condition to create your "dialog box"?
Notice that you create and endless loop without any "break" condition,
there's no way to stop the program from the gui itself which is
definitely no good idea.
Besides this you should be very careful using "while 1" statements in
any case.
For example try this:

>>> def test():
...     l = []
...     while 1:
...         l.append(1)
>>> test()

The result is of course not a python bug but a programmer's mistake.

> #I found this memory leak while working with easygui. 
> #Initially I thought, that the leak is caused by the way easygui opens 
> #and closes the window/application.
> #But plain Tkinter also has leaks. What is wrong? 

I don't have windows or mac here, but on my linux box it looks like
the only thing that's wrong is the code.

> #A friend of mine ran this script on his MAC and here is his reply:
> ##Yep, I'm seeing a .32 MB leak whenever I close the window and it 
> ##reopens.   Also seeing a high number of page faults for that process 
> ##that increase when it is closed, so I think the memory for the window 
> ##is not being deallocated, then Python hits an exception after it page 
> ##faults trying to access it, and it then spawns a new one.


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