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bug#36566: 27.0.50; debug is sometimes horribly slow
From: |
Michael Heerdegen |
Subject: |
bug#36566: 27.0.50; debug is sometimes horribly slow |
Date: |
Thu, 11 Jul 2019 00:46:00 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
Noam Postavsky <npostavs@gmail.com> writes:
> > sometimes it takes 10 or 20 seconds until the debugger pops up. I
> > debugged code using widgets (who are complicated long lists). But both
> > the number of frames and the length of the printed lists were not
> > exorbitant - a quite normal situation.
>
> Can you give an example recipe that produces the slowness? It's not
> usually slow, right? (When I trigger the debugger in master right now,
> I don't notice problem.)
I investigated a bit and found that the main factor of the sluggishness
seems to be my private (global) setting of print-gensym -> t: I can
toggle sluggishness in both the Emacs with my setup and emacs -Q just by
toggling this variable. My debugger use case involves gensyms (see
later). Ok, so it's probably mainly a printing issue.
Here is my use case: load the attached file (don't compile, I made it
contain a bug). M-x find-cmd-widget, and insert a "links" expression
by hitting the INS button and select "links" with the "expr" button.
With print-gemsym -> nil, the debugger needs approx. 2 seconds here to
pop up, and with print-gemsym -> t, approx. 12. So I wonder why this
setting makes it that slow - I would expect a small time penalty, but
such a big difference?
BTW, extra points if the debugger provided commands/ a menu to tune such
settings (like printing variables) live when using it.
find-cmd-widget.el
Description: application/emacs-lisp
Thanks,
Michael.