Memory Leak with Tkinter Canvas (Python 2.5 Win32)

[frikk]

Hey everyone.  I have been working with python for a couple years now,
but just recently built my first program with a GUI.  I decided to
start with Tkinter since it is included with the base package,
although wxWindows will likely be my next choice.  Tkinter seems to be
pretty slow for my needs.

Anyway - I am building a genetic algorithm simulator.  I have a grid
where an Ant moves around.  It is infeasible for me to update the grid
every simulation step - so I just do it at the end.  But what I've
realized is that my program performs worse and worse when I update the
grid.  Turns out there is a memory leak somewhere and I don't think it
is in my code.  The memory leak occurs only when I write (via
create_rectangle) to the canvas widget.  I wrote the following small
script to demonstrate this problem (see below).  Every time the button
is pressed, _1040KB_ is added to the RAM of wpython.exe.  This adds up
FAST.   I have not verified this on my OS X box.

As you can see- I am doing nothing other than drawing a lot of
rectangles on the canvas.  I have two questions.

  1.  Is this a bug in my usage of Tkinter? Am I somehow leaving
objects laying around that aren't being deleted? Is create_rectangle
not the appropriate function to use?)
  2.  Is there a better, quicker way to update a "grid"-like object?

Thanks,
Blaine

Current System:
Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit
(Intel)] on win32
Windows XP SP2 - all recent patches and updates

Script:

from Tkinter import *

canv = None
HEIGHT=600
WIDTH=600
def clear_grid():
    for i in range(0,HEIGHT/10):
        for j in range(0, HEIGHT/10):
            canv.create_rectangle(i*10,j*10, \
                                  i*10+10, j*10+10, \
                                  fill = "white")

def draw_window(master):
    global canv
    frame = Frame(master)

    btn_grid = Button(frame, text="draw grid", command=clear_grid)
    btn_grid.pack(side=TOP)

    canv = Canvas(frame, height=HEIGHT, width=WIDTH, bg='white')
    canv.pack()
    frame.pack()

root = Tk()
draw_window(root)
mainloop()