Re: MPS: weak hash tables

[Eli Zaretskii <eliz@gnu.org>]

> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: gerd.moellmann@gmail.com,  pipcet@protonmail.com,  emacs-devel@gnu.org
> Date: Sat, 06 Jul 2024 18:20:02 +0200
> 
> On Sat, Jul 06 2024, Eli Zaretskii wrote:
> 
> >> What else could cause it in ert-test-run-tests-batch-expensive?
> >
> > I don't know, and I don't see why we should guess.  Run that under a
> > debugger with a breakpoint in balance_an_interval that shows the
> > backtrace, and you will see the answer very quickly.
> 
> Here are the flame graphs; recorded with
> 
>   perf record -g -o ../src/emacs -Q --batch -f igc--collect \
>   -l lisp/emacs-lisp/ert-tests.el --eval \
>   '(ert-run-tests-batch-and-exit
>   "ert-test-\\(parse\\|plist\\|record\\|run-tests-batch-exp\\)")'
> 
> Both the MPS and non-MPS version compiled with -g -O2
> -fno-omit-frame-pointer.  I don't see the anything very quickly.

AFAIU, we call buffer-string, which then must copy the interval tree
of the buffer to the interval tree of the string we create.

Is that what you wanted to know and understand?