actix VS bastion

Similarly, in the Rust ecosystem, frameworks like Actix and Ractor emerge, leveraging Rust’s safety guarantees while aiming to mimic BEAM’s ability to manage failures with supervision hierarchies. I don’t think Actix allows easy communication across nodes, but Ractor is actively working to get a production-ready cluster module.

9. Actix

I think it's fairer to say the language got so much more powerful that there wasn't any point making actors a language feature when they can be built from existing orthogonal language features. You're probably looking for actix (not actix-web, just actix). There's also Lunatic built in Rust but supporting any actors compiled to WebAssembly.

Actix is an actor framework for developing concurrent applications built on top of the Tokio asynchronous runtime. It allows multiple actors to run on a single thread, but also allows actors to run on multiple threads via Arbiters. Actors can communicate with each other by sequentially exchanging typed messages.

I’ve seen frameworks for c++ (https://seastar.io/) and rust (https://github.com/actix/actix) which support what you’re describing out of the box.

The actix repository on github doesn't seem to be very active, and everyone seems to be focused on actix-web instead, is anyone out there using plain actix or any other actor-model implementation in Rust?

Rust is also another possibility: it's basically C++ but more modern with added features and safety. It can be tricky to write mathematical stuff in it, because you may not care too much about all the safety concerns Rust forces you to handle, but it can be useful to catch bugs ahead of times. Sadly, Rust seems to have no library for running programs on clusters of PCs, except maybe this one, which takes the Actor model implemented by Actix and runs it on a cluster. I don't know how tricky it is to use the Actor model for a scientific simulation, tho.

How is this better / different than https://github.com/bastion-rs/bastion ?

There are attempts to implement an Erlang/BEAM-inspired reactor/runtime/executor/ecosystem for Rust's Async, in particular Bastion. (There are also Lumen, Lunatic and Async-Backplane/Async-Supervisor.)

I would be interested in an example showing how to build a robust runtime like bastion with fault tolerance.

But the issue you're referring to, building a fault-tolerant web server where you can have granular control over killing background jobs regardless if they're blocked on a syscall, totally requires using this kind of software architecture. See Bastion.

Bastion, a Rust async runtime inspired by the beam distribution and supervision model

I don't really know much about erlang, but I think this may be along the lines of what you are thinking of: https://github.com/bastion-rs/bastion

(I also don't really think the linux kernel people would be interested...)

This reminds me of bastion. Looks like it attempts to fulfill the same needs, though I guess Lunatic has native WASM support whereas bastion might require some tweaking to have it work? Haven't worked with bastion, so that part of harder time with WASM is just a wild speculation. On the other hand bastion looks much more mature. Probably /u/vertexclique could give a more informed opinion about the difference between the two ;) I really like what these projects are putting forward.