On Sat, Jun 6, 2020 at 11:27 PM Aleix Conchillo Flaqué <aconchi...@gmail.com> wrote:
> Hi, > > in the latest guile-json, 4.1.0. I changed some code to use > for-each+string->list. The performance seemed nice and I released it. > > Christopher Lam pointed out that I could have used string-for-each > instead. I made the change but the performance degraded a lot: > > string-for-each: > > scheme@(json parser)> ,t (->bool (scm->json-string json)) > $19 = #t > ;; 17.909537s real time, 18.063382s run time. 0.207281s spent in GC. > > vs > > for-each + string->list: > > scheme@(json parser)> ,t (->bool (scm->json-string json)) > $20 = #t > ;; 2.998381s real time, 3.319349s run time. 0.471969s spent in GC. > > string-for-each is implemented in scheme here, if Im not wrong: > > http://git.savannah.gnu.org/cgit/guile.git/tree/module/rnrs/base.scm#n89 > > string->list and for-each would use C. > > Is that huge gap expected? > > This is with Guile 3.0.2. > > Forgot to mention that Chritopher also pointed out that string->list has an optimization for narrow strings: http://git.savannah.gnu.org/cgit/guile.git/tree/libguile/srfi-13.c#n294 which means it doesn't use string_ref where the scheme code has to do it. So, it might be due to this? Aleix
