bug#66221: 29.1; Animated webp image leaks memory

[Eli Zaretskii]

> Cc: Johan Claesson <johanwclaesson@bahnhof.se>, johanwclaesson@gmail.com
> From: Garjola Dindi <garjola@garjola.net>
> Date: Wed, 27 Sep 2023 19:47:43 +0200
> 
> 
> I run this on GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+
> Version 3.24.37, cairo version 1.16.0) of 2023-09-23 (built from master)
> with -Q option and got this message:
> 
> Stopping animation; animation possibly too big [10 times]
> memory increased 167716 KB
> 
> So I guess this confirms the leak.

I don't think there's a leak.  Emacs makes it hard to know when to
free the animation-related memory and which parts of it to remove,
because the low-level code which handles this memory doesn't have
anyway of knowing whether the animation will be reused.  See
bug#56546.  Maybe we have one more issue here.  Or maybe the memory
consumption is not due to the animation caches at all.  Or maybe if
you wait longer than image-cache-eviction-delay the memory does get
released.

Feel free to step through clear-image-cache and see what happens
there.