bug#31138: Native json slower than json.el

[Eli Zaretskii]

> From: yyoncho <yyoncho@gmail.com>
> Date: Sat, 23 Mar 2019 15:31:39 +0200
> Cc: Sébastien Chapuis <sebastien@chapu.is>, 
>       31138@debbugs.gnu.org
> 
> Take a look at the following piece of code:
> 
> https://gist.github.com/yyoncho/9e9c4e14734fdd9a22d6600a88a27ae1
> (with the latest emacs compiled from master)

OK.

> Unfortunately, I wasn't unable to reproduce the behaviour with "emacs -q" and 
> even it does not reproduce
> right after I load my emacs configuration but after doing some 
> navigation/coding.

Sorry, I don't think I understand what behavior you were unable to
reproduce.  Please elaborate.

> I believe that native parsing is
> calling some function list defined in the elisp space but I am unable to 
> track down this.

Maybe so, but I don't think I see a Lisp function called from json.c code.

> Please, let me know what I can do to help to diagnose this issue.

Are we still talking about too-slow performance of json-parse-string?
If so, and if you think some Lisp code is responsible for that, then
running your benchmark test under profiler.el would be the first thing
I'd suggest.