Question

I’m new to tkinter and have traced a memory leak in a project I’m doing down to a clock in my code. It turns out the memory leak happens when updating a label, the simplest example I’ve got it down to in code is:

import Tkinter as tk

class Display:
    def __init__(self, master):
        self.master = master
        self.tick()

    def tick(self):
        self.label = tk.Label(self.master, text = 'a')
        self.label.place(x=0,y=0)
        self.master.after(50, self.tick)

root = tk.Tk()
disp = Display(root)

If somebody could tell me why this leaks memory I’d be grateful.

Thanks, Matt

Answer 1

The problem appears to be that you are creating Labels without destroying them. Each time you create a new label and place it over the old one, so it is still being referenced and thus can’t be garbage collected.

Here is a slightly revised version that doesn’t leak….

import Tkinter as tk

class Display:
    def __init__(self, master):
        self.label = None
        self.master = master
        self.tick()

    def tick(self):
        if self.label:
            self.label.destroy()
        self.label = tk.Label(self.master, text = 'a')
        self.label.place(x=0,y=0)
        self.master.after(50, self.tick)

root = tk.Tk()
disp = Display(root)