bug#43016: closed (replace-region-contents takes a lot of time when called from json-pretty-print-buffer)

[GNU bug Tracking System]

Your message dated Tue, 25 Aug 2020 11:19:47 -0700
with message-id <eea085ce-e664-7256-3c5b-4fe804c62412@cs.ucla.edu>
and subject line Re: bug#43016: replace-region-contents takes a lot of time 
when called from json-pretty-print-buffer
has caused the debbugs.gnu.org bug report #43016,
regarding replace-region-contents takes a lot of time when called from 
json-pretty-print-buffer
to be marked as done.

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43016: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=43016
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--- Begin Message --- Subject: replace-region-contents takes a lot of time when called from json-pretty-print-buffer Date: Mon, 24 Aug 2020 08:25:14 +0000

I have a code which pretty prints data in json:

...

  (with-temp-buffer

    (insert data)

    (json-pretty-print-buffer)

    (write-file "data.json"))

...

This code runs for several minutes (I didn't time it, but it's about 1-2 minutes) with Emacs 27.1  It takes several seconds with Emacs 26.  Data is about 1MB on disk in pretty printed elisp format.

I tried profiling with this result:

          - progn                                                7486  98%

           - json-pretty-print-buffer                            7438  98%

            - json-pretty-print                                  7438  98%

             - replace-region-contents                           7438  98%

              + #<compiled 0x3854909>                             198   2%

           + insert                                                43   0%

           + write-file                                             5   0%

Apparently, replace-region-contents  takes 98% of the CPU time.

Using Windows version from GNU ftp :

GNU Emacs 27.1 (build 1, x86_64-w64-mingw32) of 2020-08-12

--- End Message ---

> --- Begin Message ---
>
>
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> Subject: 
>
> Re: bug#43016: replace-region-contents takes a lot of time when called from json-pretty-print-buffer
>
>
>
>
> Date: 
>
> Tue, 25 Aug 2020 11:19:47 -0700
>
>
>
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> User-agent: 
>
> Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0
>
>
>
>
> On 8/25/20 10:30 AM, Tassilo Horn wrote:
>
> > Seems to work fine for me too with all three files of this report and
> > the large one from bug#42931.  It seems like the early abort will now
> > happen shortly after MAX-SECS bounds.
>
> Thanks for checking; closing the Emacs bug report.
>
>
> --- End Message ---