Re: Emacs memory management and sluggishness

[Eli Zaretskii <eliz@gnu.org>]

> From: Óscar Fuentes <ofv@wanadoo.es>
> Date: Fri, 26 Jul 2019 21:20:17 +0200
> 
> Since a week or two typing normal text (i.e. writing this message) even
> in Fundamental Mode shows an annoying lag betwenn the keypress and the
> character showing on the screen. Sometimes it affects entire key
> sequences, and I'm no fast typist.

Is there any correlation between the lag and the GC cycles?  (Turn on
garbage-collection-messages to see.)  If it does, then there's only
one problem to investigate: why you have frequent GC cycles.

And what is your value of gc-cons-threshold?

> So my questions are: do we have a problem with memory fragmentation?

We shouldn't have.  However, there's a question whether the particular
development snapshot of a month ago you are using had some
memory-related bug.

> ((conses 16 4505904 1124616)
>  (symbols 48 76877 18)
>  (strings 32 340997 83083)
>  (string-bytes 1 10456288)
>  (vectors 16 688370)
>  (vector-slots 8 24140524 2173062)
>  (floats 8 1621 1825)
>  (intervals 56 112123 94665)
>  (buffers 992 449))
> 
> I wonder how this ends using 1.1 GB of RSS.

It doesn't.  But all these measures don't include the memory we
allocate directly, not via Lisp objects.

Also, can you tell how many bytes of text do you have in all your
buffers?  E.g., with this toy program:

  (let ((stext 0))
    (dolist (b (buffer-list))
      (setq stext (+ stext (buffer-size))))
    stext)

Having said all that, it isn't clear to me that an RSS of 1.1 GB per
se is something exceptional in a long-running session.  E.g., the
Emacs 26.2.90 session where I'm typing this, which is running for 44
days, shows an RSS of 360 MB with VM Size of 514 MB, and this is a
32-bit build of Emacs --with-wide-int.  So your 1.1 GB is not
necessarily a sign of a problem.