Re: I created a faster JSON parser

[Herman , Géza]

Eli Zaretskii <eliz@gnu.org> writes:

> > From: Herman, Géza <geza.herman@gmail.com>
> > Date: Fri, 08 Mar 2024 11:27:16 +0100
> >
> > This parser runs 8-9x faster than the jansson based parser on 
> > my
> > machine (tested on clangd language server messages).
>
> How does it do that?  Can you summarize the main ideas of your
> implementation, which make it so much faster?

My parser creates Lisp objects during parsing, there is no 
intermediate step as Emacs has with jansson.  With jansson, there 
are a lot of allocations, which my parser doesn't have (my parser 
has only two buffers, which exponentially grow. There are no other 
allocations).  But even ignoring performance loss because of 
mallocs (on my dataset, 40% of CPU time goes into malloc/free), I 
think parsing should be faster, so maybe jansson is not a fast 
parser in the first place.