wazero VS gc

Wazero, Go-based

While I'm sure Goja is great for just JavaScript, using something like wazero allows your app to support more languages (anything that compiles to WASM) while keeping the benefits of CGO.

https://wazero.io/

I've used Wazero myself on C++ -> WASM code but I'm sure you could use Emscripten or something to compile JavaScript to WASM.

and for reference see how it's done in wazero https://github.com/tetratelabs/wazero/blob/c397a402ad17e495a...

https://github.com/tetratelabs/wazero/releases/tag/v1.7.0

This includes the final release of the new optimizing compiler, which is a big improvement over the previous one.

The new version also adds experimental support for threads and snapshot/restore (setjmp/longjmp).

This is already being used by go-pgquery, all will mean that sqlc won't need to ship to almost copies of wazero (these features had been implemented on a friendly fork, and have now been up-streamed).

> Go actually has one of the best WASM runtimes https://github.com/tetratelabs/wazero

Wazero looks super cool. I saw somewhere that programs can be run with a timeout, which sounds great for sandboxing. The program input is just a slice of bytes [1], so an interesting use case would be to use something like Nats [2] to distribute programs to different servers. Super simple distributed computing!

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1: https://github.com/tetratelabs/wazero/blob/main/examples/bas...

2: https://natsbyexample.com/examples/messaging/pub-sub/go

It is slower.

The WASM runtime wazero [1] uses a compiler on amd64 and arm64 (on Linux, macOS, Windows, and FreeBSD), but the current compiler is very fast (at compiling), but very naive (generates less than optimal code).

An optimizing compiler is currently being developed, and should be released in the coming months. I'm optimistic that this compiler will cover the performance gap between WASM and modernc.

[1]: https://wazero.io

with the wasm-gc proposal you get access to structs and arrays: https://github.com/WebAssembly/gc/blob/main/proposals/gc/Ove...

with the component model's wit you get higher level types like enums, option, result and generics: https://component-model.bytecodealliance.org/design/wit.html

Destructors? Destructors are fine as a feature. You're not supposed to use them as the first choice but they are a great "safety net" for disposable types that did not get dispose to ensure that production code stays resilient to unmanaged memory leaks when presented with bad code.

Either way, you can read through this issue: https://github.com/WebAssembly/gc/issues/77

Further discussion can be found here: https://github.com/dotnet/runtime/issues/94420

Turning off destructors will not help even a little because the biggest pain points are support for byref pointers and insufficient degree of control over object memory layout.

For the audience that would be looking to use the WASM Component Model, and not be an infrastructure implementer of it, whether or not they meet some definition of a method, the component model does define things called resources [1] that have "methods". You'll hold a "handle" to it like you would in your own programming language with the expected drop and/or GC semantics (once implemented [2]) because code is generated to access it like any other FFI like C/C++.

With that in mind, the other confusing thing one may come across is composition vs linking within your WASM runtime that supports the Component Model. When you hear "composition" think of compile-time merging of libraries such that the bundle may have less unresolved dependencies of WASM code/implemented component interfaces. Anything unresolved needs to be linked at runtime with your WASM runtime of choice, like wasmtime [3]. Pretty interesting reading/potential after reading if you ask me -- sounds like you could implement something like a custom Java classloader hierarchy.

But I'd agree with a statement saying it is still a long way for general usage.

[1] https://github.com/WebAssembly/component-model/blob/5a34794d...

[2] https://github.com/WebAssembly/gc

[3] https://github.com/bytecodealliance/wasmtime/blob/ba8131c6bf...

[4] https://www.digitalocean.com/community/tutorials/java-classl...

This post might help:

https://v8.dev/blog/wasm-gc-porting

See in particular the "getting started" section near the end:

https://v8.dev/blog/wasm-gc-porting#getting-started

At a lower level the overview in the WasmGC github repo is very good:

https://github.com/WebAssembly/gc/blob/main/proposals/gc/Ove...

It may take some time for WasmGC to be usable by .NET. Based on the discussions the first version of WasmGC does not have a good way to handle a few .NET specific scenarios, and said scenarios are "post-post-mvp". [0]

My concern, of course, is that there is not much incentive for those features to be added if .NET is the only platform that needs them... at that point having a form of 'include' (to where a specific GC version can just be cached and loaded by another WASM assembly) would be more useful, despite the pain it would create.

[0] - https://github.com/WebAssembly/gc/issues/77

Yes, that's definitely true: a single GC will not be optimal for everything, or even possible. Atm interior pointers are not supported at all, for example, but they are on the roadmap for later:

https://github.com/WebAssembly/gc/blob/main/proposals/gc/Pos...

What launched now is enough WasmGC to support a big and useful set of languages (Java, Kotlin, Dart, OCaml, Scheme), but a lot more work will be required here!

GC proposal is from 2018: https://github.com/WebAssembly/proposals/issues/16 and there’s code: https://github.com/WebAssembly/gc/blob/master/proposals/gc/O...

Seems like an awefully long time for progress to be made, given all the possibilities it would unlock.

First is the size. Writing a server-side and client-side program is possible with Rust, and the resulting WASM package will be small enough. At the same time, Microsoft Blazor converts C# code to WASM, but the client delivery has to include the reduced .NET runtime, taking several megabytes for a script. The same is true for GoLang, even with an attempt to reduce the runtime delivery in TinyGo WASM. Developers want to work with their favorite languages, whether it is Java, Kotlin, Dart, C#, F#, Swift, Ruby, Python, C, C++, GoLang, or Rust. These languages produce groups of runtimes. For example, JVM and .NET have many common parts, Ruby and Python are dynamically interpreted at runtime, and all mentioned depend on automatic garbage collection. For smaller WASM packages, browser vendors can include extended runtime implementations, for example, by delivering a general garbage collector as part of WASM. Garbage collection support by WASM is currently in progress: WASM GC, .NET WASM Notes.

My understanding is that the main limitation is technical. WASM doens't do GC or the host system calling conventions and cannot interact directly with object from Javascript because of this. However, this is being worked[0] on and will be solved eventually. Even without this the performance overhead of bridging to JS is low enough that WASM frameworks can beat out React.

0: https://github.com/WebAssembly/gc/blob/main/proposals/gc/Ove...

I’ve just watched a video on YouTube from Google I/O 2023 on Flutter for the web. Kevin Moore explains that Flutter can compile to Wasm, but now that GC support has been added to the standard and WasmGC is supported in Chromium and Firefox, I’m quite intrigued.