Re: Emacs design and architecture. How about copy-on-write?

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: yantar92@posteo.net,  emacs-devel@gnu.org
> Date: Thu, 21 Sep 2023 08:55:49 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > And don't forget that the globals defined in globals.h are just those
> > we define in C.  There are many globals defined in Lisp.
> 
> Those don't contribute to the size of struct thread_state; an alist
> between threads and its local value is dynamically allocated when a
> symbol is bound locally.

I'm not sure I understand: what is the difference between a global
variable defined in C and a global variable defined, say, in
simple.el?