bug#30539: closed (26.0; `char-displayable-p' is much slower in Emacs 25 and 26)

[GNU bug Tracking System]

Your message dated Wed, 18 Nov 2020 10:30:08 -0800
with message-id 
<CADwFkmmtL=mZLofP_4a=0q6ro3MfDGYnLNwGVyJnaQjW-FL44w@mail.gmail.com>
and subject line Re: bug#30539: 26.0; `char-displayable-p' is much slower in 
Emacs 25 and 26
has caused the debbugs.gnu.org bug report #30539,
regarding 26.0; `char-displayable-p' is much slower in Emacs 25 and 26
to be marked as done.

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30539: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=30539
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--- Begin Message --- Subject: 26.0; `char-displayable-p' is much slower in Emacs 25 and 26 Date: Mon, 19 Feb 2018 14:07:40 -0800 (PST)

This is not from emacs -Q, and I do have many fonts installed.  I
repeated it from emacs -Q and I've attached those profiler reports
also.  But with emacs -Q the test code (`my-test') finished
immediately.  With my setup it took many seconds.  I use this font
by default - dunno whether that makes the difference:

(font . "-outline-Lucida 
Console-normal-normal-normal-mono-4-*-*-*-c-*-iso8859-1")
(font-parameter . "-*-Lucida Console-normal-r-*-*-14-*-*-*-c-*-iso8859-1")

Recipe I followed:

Evaluate the attached code (`throw-mule-bug.el'), then look at buffers
*CPU Profiler Report* and *Memory Profiler Report*.  I've attached these
reports as files:

throw-mule-bug-memory-report-E26-Q - Emacs 26 from emacs -Q
throw-mule-bug-cpu-report-E26-Q    - Emacs 26 from emacs -Q
throw-mule-bug-memory-report-E24 - Emacs 24.5 with my setup
throw-mule-bug-cpu-report-E24    - Emacs 24.5 with my setup
throw-mule-bug-memory-report-E26 - Emacs 26P2 with my setup
throw-mule-bug-cpu-report-E26    - Emacs 26P2 with my setup
 
In Emacs 25.3.1 and 26 `char-displayable-p' is MUCH slower
than it is in Emacs 24.5.  In 24.5 the evaluation of `my-test'
seems instantaneous.  In Emacs 26 it takes many seconds.

>From the reports, using my setup:

E26 memory:

- my-delete-if-not                         225,165,075  52%
 - let                                     222,218,069  51%
  - while                                  222,218,069  51%
   - if                                    222,218,069  51%
    - not                                  222,218,069  51%
     - funcall                             222,218,069  51%
      - my-char-displayable-p              222,218,069  51%
       - char-displayable-p                222,218,069  51%
        - cond                             222,218,069  51%
           let                             189,022,646  43%
 - while                                     2,947,006   0%
  - and                                      2,947,006   0%
   - not                                     2,947,006   0%
    - funcall                                2,947,006   0%
     - my-char-displayable-p                 2,947,006   0%
      - char-displayable-p                   2,947,006   0%
       - cond                                2,947,006   0%
          let                                1,836,898   0%

E26 cpu:

- my-delete-if-not                                1609  70%
 - let                                            1602  70%
  - while                                         1602  70%
   - if                                           1602  70%
    - not                                         1602  70%
     - funcall                                    1602  70%
      - my-char-displayable-p                     1602  70%
       - char-displayable-p                       1602  70%
        - cond                                    1602  70%
           let                                    1602  70%
 - while                                             7   0%
  - and                                              7   0%
   - not                                             7   0%
    - funcall                                        7   0%
     - my-char-displayable-p                         7   0%
      - char-displayable-p                           7   0%
       - cond                                        7   0%
          let                                        7   0%

In GNU Emacs 26.0.91 (build 1, x86_64-w64-mingw32)
 of 2018-01-22
Repository revision: 752fba992b793a74d202c9cfc3e1a92fd458e748
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''

throw-mule-bug-cpu-report-E26
Description: Binary data

throw-mule-bug-memory-report-E26-Q
Description: Binary data

throw-mule-bug-cpu-report-E26-Q
Description: Binary data

throw-mule-bug-memory-report-E24
Description: Binary data

throw-mule-bug-cpu-report-E24
Description: Binary data

throw-mule-bug-memory-report-E26
Description: Binary data

throw-mule-bug.el
Description: Binary data

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#30539: 26.0; `char-displayable-p' is much slower in Emacs 25 and 26
>
>
>
>
> Date: 
>
> Wed, 18 Nov 2020 10:30:08 -0800
>
>
>
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
> >> From: Stefan Kangas <stefan@marxist.se>
> >> Date: Wed, 18 Nov 2020 07:35:06 -0800
> >> Cc: 30539@debbugs.gnu.org
> >>
> >> > Doing (setq inhibit-compacting-font-caches t) brings back reasonable
> >> > performance.
> >> >
> >> > I can't reproduce on my GNU/Linux box, although that may just be due to
> >> > different fonts installed.  In particular, char-displayable-p never gave
> >> > me nil.
> >>
> >> Given this change:
> >>
> >> commit f34f49f35e5c000a6ee070678f43d2ca38b76cad
> >> Author: Eli Zaretskii <eliz@gnu.org>
> >> Date:   Sat Sep 7 12:26:08 2019 +0300
> >>
> >>     Set inhibit-compacting-font-caches to t by default on MS-Windows
> >>
> >> Is there anything left to do here, or should this bug be closed?
> >
> > If the problem doesn't happen on GNU/Linux, we can close this.
>
> I think this is Windows specific indeed.  Closing.
>
>
> --- End Message ---