Despite the author's obvious enthusiasm: WASM has a long way to go before it is really useful. From my humble perspective there was not much progress since the 1.0 release. As long as every access to the host (especially the GUI) is tunneled via JavaScript, one shouldn't be surprised about the low performance and the enormous memory consumption. See what happens behind the scenes when you set a pixel in the SDL API when running a WASM app in the browser. And there are plenty of good alternatives for the desktop already.
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It does feel like WebAssembly development has stalled after the initial release. There are proposals for reference types, garbage collection, and host bindings that would greatly expand a WebAssembly binary's capabilities, but they haven't been implemented in any browser, much less standardized yet.
WebAssembly proposals tracker: https://github.com/WebAssembly/proposals
WebAssembly reference types (https://github.com/WebAssembly/reference-types/blob/master/p...) looks like the blocker for a lot of things, and it's in the final spec phase at least.
In Chrome, it's behind a flag since 78, which went stable in Oct 22 2019: https://chromestatus.com/features/5166497248837632 But also under active development? https://bugs.chromium.org/p/v8/issues/detail?id=7581
Supposedly implemented in Firefox two years ago: https://bugzilla.mozilla.org/show_bug.cgi?id=1444925
Nothing in Safari, of course.
Where is it now though?
> but they haven't been implemented in any browser, much less standardized yet.
Reference types already implemented. GC is not really needed for non-managed languages like C++ or Rust. Interface types in progress.
See this: https://webassembly.org/roadmap
That is also my impression.
And the fact that Mozilla has problems and has to realign is certainly not helping.
I'm still waiting for tail call optimization. By not having support for it, a bunch of languages are either forced to not bother with WASM, or have to do something like trampolines and give up performance.
>WASM has a long way to go before it is really useful.
I disagree.
I can already write decent C# applications that run in browser while using already existing C# libraries for e.g parsing text and it will run fine.
So, WebAssembly allows me to use existing code C# and move it to the browser while developing in my fancy language instead of Javascript and I think it (dropping js) is very solid pros
I just think tooling (visual studio, vs code, rider, etc...) around C#'s Blazor has to mature in order to make this kind of development worth considering, but I wouldnt call that "long way to go"
> I can already write decent C# applications that run in browser .. it will run fine.
It is undoubtedly technically possible, but not really practicable, unless you accept an exorbitant speed-down and much higher memory consumption than e.g. when running in DotNet. Personally, I don't find that attractive in any way, nor do I find it particularly efficient.
I've been trying it on small CRUDs, so nothing impressive was happening on the front side, so I didn't really notice those problems.
I think DLLs size and lack of DOM access was the biggest problem at the moment I've been testing it
Try with a representative application where a whole JS based single page app is implemented in another language than JS (e.g. C++/Qt), which is one of the core benefit propositions made by WASM.
I think you have the performance differences backwards, wasm is usually quite a bit faster than comparable javascript. While it's true that right now there are additional overhead costs for browser APIs, that's changing, but it's also misunderstanding the value proposition of wasm. You can write an entire front end web application if you want, but it really shines for library code and computationally expensive code. And of course, the distribution benefits mentioned in the article.
> wasm is usually quite a bit faster than comparable javascript
Even if true, it doesn't help much if you have to marshall through JS for nearly every call.
> You can write an entire front end web application if you want
One of the core benefit propositions was the possibility to write browser applications in any language, not just JS.
I think you're just misunderstanding what wasm is. Writing browser applications in any language was never a "core benefit proposition", it was just something that you could do with the tooling. The value has always been in the library/platform layer. Objectively pure wasm is faster than pure javascript, subjectively the additional type safety from writing in Rust (which is practically speaking what most people shipping wasm write their source code in) makes people more confident that their complex code works.
Outside of a few hobbyists, nobody is writing entire web applications in wasm. We already have great frameworks for dealing with UI/DOM stuff.
To quote from https://webassembly.org/:
"Wasm is designed as a portable compilation target for programming languages, enabling deployment on the web for client and server applications."
So did they mean only GUI-less client applications?
EDIT: also e.g. this source https://developer.mozilla.org/en-US/docs/WebAssembly/Concept... makes it clear that porting e.g. C++ GUI applications is an intended feature, not just a silly idea of some hobbyists.
Browser API calls add 1us of overhead. If your code is conscious of this, then it won’t be a problem. Much of the thought process behind react is to update the dom as little as possible, because it usually takes a while to repaint. Similarly, your WASM code will have this small overhead, but even 1000 calls is just 1ms. Regardless, there is still much more performance gains to be had by WASM-compatible languages when providing computationally expensive features.
My favorite example is Rapier http://rapier.rs/, check out the 3D demos. It blows every JS physics engine out of the water, and it’s using Conrod, a native gui library which has a webgl backend.
Looks like a nice physics engine, but I wouldn't say it blows JS engines out of the water performance wise. They are surprisingly fast these days.
Ammo js: http://kripken.github.io/ammo.js/examples/webgl_demo/ammo.ht...
Ammo wasm: http://kripken.github.io/ammo.js/examples/webgl_demo/ammo.wa...
They can be faster, but it is still insane how fast JS interpreters have become. So for smaller application it might be ok to stay in JS land.
Thanks for the link. I tried the cubes 3d demo which takes about 45 seconds on my laptop until no cube moves anymore (around step 590); probably not the expected performance; if I find time I will run the Rust version locally.
I tried the same thing and it took 4 seconds on my 8 year old computer.
>Even if true, it doesn't help much if you have to marshall through JS for nearly every call.
If your particular front end code is dominated by many calls to the DOM, then WASM may be a net performance loss currently, yes.
In cases where you are doing something computationally heavy then periodically updating the dom with results, then WASM can be a huge win.
In cases where the performance is fine either way, being able to use one language server and client is a huge win. I am already doing useful things with WASM and Rust. It is a very very nice workflow.
I've rewritten hot loops (decompression & texture detiling) from JavaScript into specialized AssemblyScript and seen a decent (2-3x) perf boost? I'm not sure how much of that is "running hot" in JS, since in the examples back then I was probably only doing it for ~100 textures. I can't imagine beating JS with a giant STL-using app with a clang-based toolchain, but the AOT nature helps a lot for hot loops; the kind of stuff you'd write custom asm for in a game engine.
Of course I was making sure to do as minimal memory transfer as possible, and I already use a lot of weird patterns to try to minimize GC in JS.
https://github.com/magcius/noclip.website/blob/master/src/gx...
https://github.com/magcius/noclip.website/blob/master/src/as...
> Even if true, it doesn't help much if you have to marshall through JS for nearly every call.
If you're doing a lot of cheap calls, it's probably not the optimal way to get a performance boost. I think Web Assembly shines at taking an expensive function, and doing it faster. For example, let's say I wanted to multiple a few large matricies of values. In Javascript this would be VERY slow. In Web Assembly it would be a bit faster, but then Web Assembly plus Web GPU allows me to do it REALLY fast. Yes, I'd then have to marshal the end result back to javascript but that's still cheaper then trying to do all that math natively in Javascript.
Webassembly is not designed to replace javascript. It works along side it.
Calling from WASM to JS is "reasonably fast" now, of course it doesn't make any sense to make such a call for setting a single pixel, but this doesn't make sense anywhere else either.
IMHO the current main problem of WASM running in browsers is not WASM, but that most "HTML5 APIs" are too high level, too specialized, and built under the assumption that Javascript is too slow to allow lower level, more general APIs (worst example of this outdated thinking is WebAudio).
The next problem is: browser updates regularly break things, often unintended, but sometimes intended (like Chrome's splendid decision to start WebAudio contexts muted, which broke pretty much every WebAudio demo on the web).
And finally: Features behind "security gates", some features just show a passive popup - but not that different browsers could ever agree on what the best UX is for this, each one behaves differently), other features show a popup that requires a user interaction. Other feature can only be used from within in a "short-lived input event handler". Yet other features only work over a HTTPS connection. And yet other features require specific response headers to be set by the web servers (like SharedArrayBuffer support in Firefox, and probably soon-ish Chrome).
Please browser vendors I beg of you, make up your damn mind already about how to handle such security-sensitive features in a consistent way.
Then there's the always lingering deprecation threat, like WebAudio's ScriptProcessorNode, despite it working perfectly fine for situations where audio samples must be generated on the browser thread and audio synthesis can't be moved into the audio thread)
All of this combined makes the browser platform a quite frustrating platform to work on for anything that isn't very simple webpages. Not as bad as Android development (which is at the bottom of my list), but it's starting to get close.
PS: Despite my ranting, I do actually like writing WASM stuff and putting it up on the web, at least this can be done without going through hoops like on closed platforms (e.g. Android or iOS). But it really could be better. Most of the actual problems are not something the people working on WASM can do anything about though.
> but this doesn't make sense anywhere else either
But that's exactly what happens when you draw into an SDL raster window. Even when you have vector drawing operations on higher level, eventually pixels are modified; you can of course combine drawing operations and transport a patch of the screen to the host, but this still goes through an impressive machinery with a lot of copying.
> All of this combined makes the browser platform a quite frustrating platform to work on for anything that isn't very simple webpages
Well, eventually we're on the same page.
SDL also does other weird things (or at least did), like rendering each 2D sprite in its own draw call.
The way to handle something like setting unique pixels is to keep a pixel buffer in memory on the WASM side, set the pixels in there, and then once per frame copy this pixel buffer into a WebGL texture and render this through a single WebGL draw call, or blit the pixel buffer to a 2D canvas if WebGL is not an option (also once per frame).
Unfortunately with WASM we don't have so many other ways to migrate a desktop GUI application at the moment. If I have to redesign the whole existing GUI application to run on WASM, the technology is not really attractive.
Microsoft is betting on (the not yet mature) Blazor [1,2] framework for porting .NET applications to WASM. Here's a CRUD app WASM example [3] -- there's an initial load time, but once loaded the app seems pretty responsive. There's a bunch more demos here [4] to get a sense of the performance.
There's even a HN clone built on Blazor [5]. This very thread can be found there.
[1] https://dotnet.microsoft.com/apps/aspnet/web-apps/blazor
[2] https://devblogs.microsoft.com/aspnet/blazor-webassembly-3-2...
[3] https://becksblazor.azurewebsites.net
[4] https://github.com/StevenTCramer/awesome-blazor#samples-and-...
> low performance and the enormous memory consumption
That has not been what I've seen from it. People have made video editors and ported game into web pages. You make a lot of claims in this thread about speed and memory but don't back any of them up.
Here are some examples: https://www.qt.io/qt-examples-for-webassembly ; some of them don't even start on my 32 bit machine because more than 2GB RAM would need to be allocated.
EDIT: I'm using Firefox 78.0.2 on Linux i386.
Just tried the pizza shop example on my desktop. Linux x86-64 (i7 quad core, 8GB RAM, Firefox 80.0.1)
FF memory usage: blank page = 285MB, peak = 839MB, steady-state = 340MB. Load time: ~6s wall clock time.
Tried it with my Windows 10 Desktop too (i7 quad core, 32GB RAM, Firefox 80.0.1).
FF memory usage: blank page = 215MB, peak = 1015MB, steady-state = 658MB. Load time: ~3s wall clock time.
Once loaded, the UI was very responsive.
Thanks for the measurements. That's much faster indeed than on my laptop and even quite decent (besides the peak memory use). Compared to the C++ native version of similar apps on my Linux i386 and Windows x86 this is about factor 10/20 (Linux/Windows) more RAM in steady state and factor 25/30 (Linux/Windows) in peak. Start time of the C++ apps (not QML) is factor 6/3 (Linux/Windows) slower.
Btw. I noticed that on my machine memory use is higher on Chromium and performance even worse than with Firefox. So it seems to depend on browser type/version, and someone in this thread said that there is no support for Safari.
These load in about 1 second for me and everything is almost instant and fluid on firefox 80. The firefox process running them uses 284MB of memory.
On which OS? Have you watched peak memory use, or is this steady state?
True, but we have a user-case where we have a library we could conceivably rewrite in e.g Rust and run multithreaded on the server or single-threaded inside a Webworker compiled as Wasm.
This is for a pure logic component of course
Wasn't it the primary intention of WASM/Emscripten that you precisely don't have to rewrite existing libraries, but simply compile them for WASM and reuse them in the browser?
Google seems to think it is currently useful. They have a WASM back end to tensorflow.js to use when WebGL isn’t available and you only have CPUs to run on
https://blog.tensorflow.org/2020/03/introducing-webassembly-...