Re: Question about memory usage

[Michał Kondraciuk]

On 04/04/2018 08:55 AM, Eli Zaretskii wrote:
> > > Did you try not setting buffer-undo-list at all?  What did you see
> > > then?
> >
> > Emacs behaves as expected, i.e. memory usage is ~20MB all the time.
>
> OK, so what is your question now?  Are you asking, like Stefan, why
> setting buffer-undo-list to nil in this case makes a difference, or
> are you asking a more general question (and if the latter, what are
> you asking)?

I found out what the problem was:

(while t
  (with-temp-buffer
    (setq buffer-undo-list nil)
    (insert "a")
    (print (length undo-auto--undoably-changed-buffers)
           #'external-debugging-output)))

The variable undo-auto--undoably-changed-buffers was storing a lot of 
killed buffers. There's a timer that periodically clears this variable, 
but it didn't get a chance to run, since Emacs was never idle. Calling 
sit-for inside the loop solves this - not that it matters, because this 
is not "normal" code. Thanks for the responses.