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Hey HN, one of the creators here! I made it at Cruise because it was super painful to develop https://webviz.io https://webviz.io with manual memory management

Hey HN, one of the creators here! I made it at Cruise because it was super painful to develop https://webviz.io https://webviz.io with manual memory management (lots of ArrayBuffers), WebWorkers, etc. I thought that there must be a better way. Very curious to hear stories from other folks building intensive stuff in the browser. How are you dealing with performance issues in Javascript? Have you tried using Rust or C++ with WebAssembly for parts of your apps? How did you make 2d/3d rendering faster? Would you want to use something like Zaplib? (You may have seen my blog yesterday about the subtleties about Wasm vs JS/TS: https://zaplib.com/docs/blog_ts++.html https://zaplib.com/docs/blog_ts++.html)

tylerhou 5y ago
Curious as to what the JS bridge overhead is like for both latency and throughput. What would the performance look like if you tried to serialize DOM updates over the bridge and replay them on the JavaScript side so that you could build DOM UIs? Have you measured # of updates per ~16ms? (I know there is some proposal that might allow WASM to interact with the DOM directly too, but I don't know how likely it will be merged.)
- janpaul123 5y ago
  Overhead of calling into JS from Wasm is very low; DOM calls are no problem since the DOM call itself is much slower than the overhead of switching from Wasm to JS. See e.g. this article from ~4 years ago: https://hacks.mozilla.org/2018/10/calls-between-javascript-and-webassembly-are-finally-fast-%F0%9F%8E%89/ https://hacks.mozilla.org/2018/10/calls-between-javascript-a... There are even some libraries that try to mimic React directly from Rust, such as https://yew.rs/ https://yew.rs/ (though in my experience they can be a bit harder to use than Zaplib, since they require you to learn about traits, closures, etc, and tend to also run into borrow checker issues more often -- all of those are things we try to avoid having to learn in Zaplib!)
pjmlp 5y ago
> How did you make 2d/3d rendering faster? Using the obvious way, GL shaders. The amount of time spent on the CPU side is mostly irrelevant, preparing buffers that can only be done from JS code anyway.

tylerhou 5y ago

Curious as to what the JS bridge overhead is like for both latency and throughput. What would the performance look like if you tried to serialize DOM updates over the bridge and replay them on the JavaScript side so that you could build DOM UIs? Have you measured # of updates per ~16ms? (I know there is some proposal that might allow WASM to interact with the DOM directly too, but I don't know how likely it will be merged.)

janpaul123 5y ago
Overhead of calling into JS from Wasm is very low; DOM calls are no problem since the DOM call itself is much slower than the overhead of switching from Wasm to JS. See e.g. this article from ~4 years ago: https://hacks.mozilla.org/2018/10/calls-between-javascript-and-webassembly-are-finally-fast-%F0%9F%8E%89/ https://hacks.mozilla.org/2018/10/calls-between-javascript-a... There are even some libraries that try to mimic React directly from Rust, such as https://yew.rs/ https://yew.rs/ (though in my experience they can be a bit harder to use than Zaplib, since they require you to learn about traits, closures, etc, and tend to also run into borrow checker issues more often -- all of those are things we try to avoid having to learn in Zaplib!)

pjmlp 5y ago

> How did you make 2d/3d rendering faster? Using the obvious way, GL shaders. The amount of time spent on the CPU side is mostly irrelevant, preparing buffers that can only be done from JS code anyway.