Am Sat, 17 Oct 2015 16:27:06 +0000
schrieb Sean Kelly <s...@invisibleduck.org>:

> On Saturday, 17 October 2015 at 16:14:01 UTC, Andrei Alexandrescu 
> wrote:
> > On 10/17/15 6:43 PM, Sean Kelly wrote:
> >> If this is the benchmark I'm remembering, the bulk of the time 
> >> is spent
> >> parsing the floating point numbers. So it isn't a test of JSON 
> >> parsing
> >> in general so much as the speed of scanf.
> >
> > In many cases the use of scanf can be replaced with drastically 
> > faster methods, as I discuss in my talks on optimization 
> > (including Brasov recently). I hope they'll release the videos 
> > soon. -- Andrei
> 
> Oh absolutely. My issue with the benchmark is just that it claims 
> to be a JSON parser benchmark but the bulk of CPU time is 
> actually spent parsing floats. I'm on my phone though so perhaps 
> this is a different benchmark--I can't easily check. The one I 
> recall came up a year or so ago and was discussed on D.general.

1/4 to 1/3 of the time is spent parsing numbers in highly
optimized code. You see that in a profiler the number parsing
shows up on top, but the benchmark also exercises the
structural parsing a lot. It is not a very broad benchmark
though, lacking serialization, UTF-8 decoding, validation of
results etc. I believe the author didn't realize how over time
it became the go-to performance test. The author of RapidJSON
has a very in-depth benchmark suite, but it would be a bit of
work to get something non-C++ integrated:
https://github.com/miloyip/nativejson-benchmark
It includes conformance tests as well.

-- 
Marco

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