Re: JSON encoding and decoding performance

[Eli Zaretskii <eliz@gnu.org>]

> From: Clément Pit--Claudel <cpitcla@mit.edu>
> Date: Sat, 15 Apr 2017 01:35:45 -0400
> 
> I'm running into performance issues with JSON encoding and decoding.  I have a language mode whose eldoc function makes a call to a language server running as a subprocess, and small lags tend to be visible when moving quickly around the buffer.  Profiling suggests that roughly 25 percent of the time is spent encoding and decoding JSON strings.

Can you show the profiles?  IME, the devil is almost always in the
details.

> Would there be strong objections to supporting a C JSON library in addition to the current ELisp implementation?  This was suggested at one point in https://lists.gnu.org/archive/html/bug-gnu-emacs/2015-03/msg00770.html .  It would be similar in spirit to supporting libxml-parse-region along xml-parse-region, and it could provide nice speed boosts to json-heavy ELisp programs.

Since we have modules now, something that wasn't available back then,
you could roll your own library, right?

Anyway, I think more details about the bottlenecks would be necessary
to make the decision on what would be the best course of action.

Thanks.