design VS pyodide

First of all, a quick rundown of what WASM is. It stands for Web Assembly. In essence, similar to how Java compiles down to a bytecode that is interpreted by a Java Virtual Machine, Web Assembly is a different bytecode interpreted by the browser. Many different languages can compile into WASM, and Javascript can interface with it like a module. In my case, I wrote a lot of the source code in Rust and compiled it down to a WASM module, then called into it from Javascript.

WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed as a portable compilation target for programming languages, enabling deployment on the web for client and server applications. - https://webassembly.org

With WebAssembly we can compile our C++ codebase into a wasm module for the browser. So when you look at a SciChart.js chart you're actually seeing our C++ graphics engine wrapped for JavaScript.

I should add, however, that the unmentioned elephant in the room is V8 JIT (TurboFan), which simply doesn't handle irreducible control flow. While there are some valid theoretical arguments around the current arrangement in Wasm, looking at the history of the associated discussions makes it pretty obvious that having V8 support Wasm and generate fast code similar to what it can do for asm.js was an overriding concern in many cases. And Google straight up said that if Wasm has ICF, they will not bother supporting such cases, so it will be done by a much slower fallback:

https://github.com/WebAssembly/design/issues/796#issuecommen...

AFAIK no other Wasm implementation has the same constraint - the rest generally tend to desugar everything to jumps and then proceed from there. So this is, at least to some extent, yet another case of a large company effectively forcing an open standard to be more convenient for them specifically.

https://github.com/WebAssembly/design/issues/1397

> Currently allocating more than ~300MB of memory is not reliable on Chrome on Android without resorting to Chrome-specific workarounds, nor in Safari on iOS.

That's about allocating CPU memory but the GPU memory situation is similar.

As far as I can tell (5 minutes of internet research) this was to allow easier compilation to JavaScript as a fallback in the days when WASM wasn't widely supported.

"Please add goto" issue has been open since 2016:

https://github.com/WebAssembly/design/issues/796

Most interesting comment:

> The upcoming Go 1.11 release will have experimental support for WebAssembly. This will include full support for all of Go's features, including goroutines, channels, etc. However, the performance of the generated WebAssembly is currently not that good.

> This is mainly because of the missing goto instruction. Without the goto instruction we had to resort to using a toplevel loop and jump table in every function. Using the relooper algorithm is not an option for us, because when switching between goroutines we need to be able to resume execution at different points of a function. The relooper can not help with this, only a goto instruction can.

> It is awesome that WebAssembly got to the point where it can support a language like Go. But to be truly the assembly of the web, WebAssembly should be equally powerful as other assembly languages. Go has an advanced compiler which is able to emit very efficient assembly for a number of other platforms. This is why I would like to argue that it is mainly a limitation of WebAssembly and not of the Go compiler that it is not possible to also use this compiler to emit efficient assembly for the web.

^ https://github.com/WebAssembly/design/issues/796#issuecommen...

When I implemented a WASM compiler, the only source of float-based non-determinism I found was in the exact byte representation of NaN. Floating point math is deterministic. See https://webassembly.org/docs/faq/#why-is-there-no-fast-math-... and https://github.com/WebAssembly/design/blob/main/Nondetermini....

> To work with GC, you need some way to track if the GC'd object is accessible in WASM itself.

I've never heard of a GC with that kind of API. Usually any native code that holds a GC reference would either mark that reference as a root explicitly (eg. https://github.com/WebAssembly/design/issues/1459) or ensure that it can be traced from a parent object. Either way, this should prevent collection of the object. I agree that explicitly checking whether a GC'd object has been freed would not make any sense.

> The reason why you probably need a custom string type is so you can actually embed string literals without relying on interop with the environment.

WASM already has ways of embedding flat string data. This can be materialized into GC/heap objects at module startup. This must happen in some form anyway, as all GC-able objects must be registered with the GC upon creation, for them to be discoverable as candidates for collection.

Overall I still don't understand the issue. There is so much prior art for these patterns in native extensions for Python, PHP, Ruby, etc.

Giving you a buffer that grows is the allocation approach I am talking about. This is not how your OS works. Your OS itself works with an allocator that does a pretty good job making sure that your memory ends up not fragmented. Because WASM is in between, the OS is not in control of the memory, and instead the browser is. The browser implementation of "bring your own allocator" is cute but realistically just a waste of time for everybody who wants to deploy a wasm app because whatever allocator you bring is crippled by the overarching allocator of the browser messing everything up.

It seems like the vendors are recognizing this though, with firefox now having a discard function aparently!

https://github.com/WebAssembly/design/issues/1397

We implemented an in-browser Python editor/interpreter built on Pyodide over at Comet (our users are data scientists who need to build custom visualizations quite often, and the most familiar language for most of them is Python).

One of the issues you'll run into is that Pyodide only works by default with packages that have pure Python wheels available. The team has developed support for some libraries with C dependencies (like scikit-learn, I believe), but frameworks like PyTorch are particularly thorny (see this issue: https://github.com/pyodide/pyodide/issues/1625 )

We ended up rolling out a new version of our Python visualizations that runs off-browser, in order to support enough libraries/get the performance we need: https://www.comet.com/docs/v2/guides/comet-ui/experiment-man...

Thank you! Yes, one of the items in the Roadmap is support for Pyodide (https://github.com/pyodide/pyodide) for running in-browser python on the results of each of the code blocks! This should allow most ML libs to be usable in-browser! This is pretty high-up on our priority list.

If I understand correctly, WASM only makes sense for compiled languages, you can run the python interpreter in WASM of course[1], but that will be at a significant performance disadvantage to the native javascript interpreter, and it's also something that has to be loaded every time you load the website.

[1]: https://github.com/pyodide/pyodide

If you absolutely need something comparable to Sympy, then one option might be to figure out how to best call Sympy from Rust. e.g. - RustPython, although it seems like Sympy isn't supported yet - Pyodide, and figuring out how to run it outside of a web browser. Probably also not very easy. - PyPy, and having a pretty simple Python binary for every platform - ...

For running programming languages other than JavaScript in the browser there is Emscripten and WebAssembly. There is v86, where a Linux build is compiled to WASM. Folks have written QuickJS into a Linux build compiled to WASM, Node.js into the Linux buildroot https://github.com/cemalgnlts/now, so Python or CPython can be written to the image and loaded into the browser as WASM as well https://github.com/pyodide/pyodide.

There's a Python runtime that runs on WebAssembly (https://github.com/pyodide/pyodide). I have no idea what it's like, I've never used it.

Still in a quest to provide some tooling to quickly compose documentation websites: https://github.com/synw/docdundee . As I have tons of libs to document and was tired of managing restructured language for readthedocs I started with this, and now it has executable Python examples in the frontend via a Pyodide wrapper composable: usePython

This project's brand new and a lil hacky, but I've already reached out to the scikit-learn team, and they recommended that I experiment with using Pyodide as an alternative backend for the Python bridge.