Performance of std.json

[Masahiro Nakagawa via Digitalmars-d]

On Monday, 2 June 2014 at 00:18:19 UTC, David Soria Parra wrote:
> Hi,
>
> I have recently had to deal with large amounts of JSON data in 
> D. While doing that I've found that std.json is remarkable slow 
> in comparison to other languages standard json implementation. 
> I've create a small and simple benchmark parsing a local copy 
> of a github API call 
> "https://api.github.com/repos/D-Programming-Language/dmd/pulls" 
> and parsing it 100% times and writing the title to stdout.
>
> My results as follows:
>   ./d-test > /dev/null  3.54s user 0.02s system 99% cpu 3.560 
> total
>   ./hs-test > /dev/null  0.02s user 0.00s system 93% cpu 0.023 
> total
>   python test.py > /dev/null  0.77s user 0.02s system 99% cpu 
> 0.792 total
>
> The concrete implementations (sorry for my terrible haskell 
> implementation) can be found here:
>
>    https://github.com/dsp/D-Json-Tests/
>
> This is comapring D's std.json vs Haskells Data.Aeson and 
> python standard library json. I am a bit concerned with the 
> current state of our JSON parser given that a lot of 
> applications these day use JSON. I personally consider a high 
> speed implementation of JSON a critical part of a standard 
> library.
>
> Would it make sense to start thinking about using ujson4c as an 
> external library, or maybe come up with a better 
> implementation. I know Orvid has something and might add some 
> analysis as to why std.json is slow. Any ideas or pointers as 
> to how to start with that?

BTW, my acquaintance points out your haskell code is different 
from other samples.
Your haskell code parses JSON array only once. This is why so 
fast.
He uploads same behaviour code which parses JSON array at each 
loop. Please check it.

https://gist.github.com/maoe/e5f72c3cf3687610fe5c

On my env result:

% time ./new_test > /dev/null
./new_test > /dev/null  1.13s user 0.02s system 99% cpu 1.144 
total
% time ./test > /dev/null
./test > /dev/null  0.02s user 0.00s system 91% cpu 0.023 total