json-benchmark VS image-png

I don’t really understand what this is trying to prove:

- you don’t seem to specify the size of the input. This is the most important omission

- you are constructing an optimised representation (in this case, strict with fields in the right places) instead of a generic ‘dumb’ representation that is more like a tree of python dicts

- rust is not a ‘moderately fast language’ imo (though this is not a very important point. It’s more about how optimised the parser is, and I suspect that serde_json is written in an optimised way, but I didn’t look very hard).

I found[1], which gives serde_json to a dom 300-400MB/s on a somewhat old laptop cpu. A simpler implementation runs at 100-200, a very optimised implementation gets 400-800. But I don’t think this does that much to confirm what I said in the comment you replied to. The numbers for simd json are a bit lower than I expected (maybe due to the ‘dom’ part). I think my 50MB/a number was probably a bit off but maybe the python implementation converts json to some C object and then converts that C object to python objects. That might half your throughput (my guess is that this is what the ‘strict parse’ case for rustc_serialise is roughly doing).

[1] https://github.com/serde-rs/json-benchmark

But the code OP posted deserializes JSON without knowing anything about the structure, which is known to be slow in serde-json and doesn't appear to be the focus for the library. The json and json-deserializer crates should perform much better in that scenario.

Of course that doesnt mean that in practice the available libraries are as optimized. Did you try actix? It tends to be faster than rocket. Also json-rust and simd-json are usually faster than serde-json, when you don't deserialize a known structure. Here are some benchmarks: https://github.com/serde-rs/json-benchmark

The data for the test is taken from here: https://github.com/serde-rs/json-benchmark/tree/master/data

Here are some benchmarks https://github.com/serde-rs/json-benchmark

I found two projects: * https://github.com/djkoloski/rust_serialization_benchmark - doesn't use Serde zero copy * https://github.com/serde-rs/json-benchmark - has copy vs borrowed, but the results were the same for both, so something's off there

Rust has a good enough standard library (I’d say comparable to C++), that you don’t really need packages for a lot of stuff. Most of my projects have 1 or 2 dependencies. Most of the time I am pulling in a JS parser (serde) and a parallelization library (rayon). These are both high performance libraries that make writing very fast (serde can handle 850 MB/s on a 5 year old laptop cpu per their benchmarks). Rayon is one of the best parallelism libraries I’ve worked with.

Encoding images to PNG with the "fast" compression mode is now an order of magnitude faster. This is achieved using a custom Zlib compression implementation that leverages assumptions about the patterns in PNG data to get reasonable compression ratios at phenomenal speeds.

However, the latest release of the png crate - published less than a day ago - has an ultrafast compression mode that's slightly faster than the QOI reference implementation at a comparable compression ratio. So basically you get the properties of QOI in a much more widely used image format.

In other areas, miniz_oxide is faster than miniz, Symphonia is faster than ffmpeg on most codecs, the not-yet-announced zune-png beats both libpng and the more heavily optimized libspng, and the png crate is getting considerable improvements too and also beats libpng.

gif, png, zune-jpeg are on par with their C counterparts in terms of performance

Fun fact: libpng-sys was so difficult to create safe Rust wrapper for that people just wrote their own, 100% safe Rust PNG decoder: https://github.com/image-rs/image-png

I didn't get time to finish the full spec for my attempt at a PNG decoder but it was working on common cases and was faster than image-png at the time https://users.rust-lang.org/t/new-rust-png-decoding-library/30952. I suspect it's not the case anymore since it changes it's deflate crate usage. Here is the perf issue on the image crate https://github.com/image-rs/image-png/issues/114. My code was way simpler than the one in the image crate so that might still be worth a read if you are interested.

The crate actually forbids unsafe. There's nothing necessarily wrong with unsafe code, but not having it provides a nice assurance. Plus if you are willing to tolerate (well audited) unsafe code then you may well be better off just using libpng.