GNU bug report logs - #43016
replace-region-contents takes a lot of time when called from json-pretty-print-buffer

Previous Next

Full log

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: ljell <laszlomail <at> protonmail.com>
To: "bug-gnu-emacs <at> gnu.org" <bug-gnu-emacs <at> gnu.org>
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

[Message part 1 (text/plain, inline)]

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

[Message part 2 (text/html, inline)]

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.