Subject: bug#43389: 28.0.50; Emacs memory leaks using hard disk all time

From: Stefan Monnier <[email-masked]>
Date: Thu, 10 Dec 2020 14:21:16 -0500

> Trevor reported several times that automatic GC is fast as usual, but
> manual invocations of "M-x garbage-collect" take much longer, many
> minutes.  I don't understand how this could happen, because both
> methods of invoking GC do exactly the same job.

Indeed, that makes no sense.  The only thing that comes to mind is that
when they do `M-x garbage-collect` the 15 minutes aren't actually spent
in the GC but in some pre/post command hook or something like that
(e.g. in `execute-extended-command--shorter`)?

Do we have a `profiler-report` available for those 15 minutes?
I've taken a quick look at the massive threads in that bug report,
but haven't had the time to read in detail.  AFAICT we don't have a
profiler output for those 15minutes, so it would be good to try:

    M-x profiler-start RET RET
    M-x garbage-collect RET     ;; This should presumably take several minutes
    M-x profiler-report RET

and then shows us this report (using C-u RET on the top-level elements
to unfold them).

        Stefan