tokio VS async-std

Being able to control nondeterminism is particularly useful for testing and debugging. This allows creating reproducible test environments, as well as discrete-event simulation for faster-than-real-time simulation of time delays. For example, Cardano uses a simulation environment for the IO monad that closely follows core Haskell packages; Sui has a simulator based on madsim that provides an API-compatible replacement for the Tokio runtime and intercepts various POSIX API calls in order to enforce determinism. Both allow running the same code in production as in the simulator for testing.

tokio / hyper / toml / serde / serde_json / json5 / console

tokio - An asynchronous runtime for Rust

3. Tokio

The AWS SDK makes use of the async capabilities in the Tokio library. So when you see async in front of a fn that function is capable of executing asynchronously.

Petar is also looking at implementing concurrency the way it is in Go to have a fully functional virtual machine as it is in the spec. This would likely attract more external contributors to developing the VM. One advantage of Rust is that, with the concurrency model, there is already an extensive library called Tokio which he can use. Petar stresses that this isn’t easy, but he believes it’s achievable, at least as a research topic around determinism and concurrency.

Another thing to point out is that async is a thing in Rust. I'm not going to begin to dive into this paradigm in this article, but know it's handled by the awesome Tokio framework.

So I started by using Tokio, a popular async runtime. The docs and samples helped me get a simple outbound TCP connection working. The Rust async book also had a lot of good explanations, both practical and digging into the details of what a runtime does.

Regarding the quote:

> The Original Sin of Rust async programming is making it multi-threaded by default. If premature optimization is the root of all evil, this is the mother of all premature optimizations, and it curses all your code with the unholy Send + 'static, or worse yet Send + Sync + 'static, which just kills all the joy of actually writing Rust.

Agree about the melodramatic tone. I also don't think removing the Send + Sync really makes that big a difference. It's the 'static that bothers me the most. I want scoped concurrency. Something like <https://github.com/tokio-rs/tokio/issues/2596>.

Another thing I really hate about Rust async right now is the poor instrumentation. I'm having a production problem at work right now in which some tasks just get stuck. I wish I could do the equivalent of `gdb; thread apply all bt`. Looking forward to <https://github.com/tokio-rs/tokio/issues/5638> landing at least. It exists right now but is experimental and in my experience sometimes panics. I'm actually writing a PR today to at least use the experimental version on SIGTERM to see what's going on, on the theory that if it crashes oh well, we're shutting down anyway.

Neither of these complaints would be addressed by taking away work stealing. In fact, I could keep doing down my list, and taking away work stealing wouldn't really help with much of anything.

The PHP <-> Rust bindings are provided by https://github.com/Nicelocal/ext-php-rs/ (our fork of https://github.com/davidcole1340/ext-php-rs with a bunch of UX improvements :).

php-tokio's integrates the https://revolt.run event loop with the https://tokio.rs event loop; async functionality is provided by the two event loops, in combination with PHP fibers through revolt's suspension API (I could've directly used the PHP Fiber API to provide coroutine suspension, but it was a tad easier with revolt's suspension API (https://revolt.run/fibers), since it also handles the base case of suspension in the main fiber).

But maybe check out the discussion here https://github.com/async-rs/async-std/pull/631 or something (the blog post was linked on the end of it)

Have a look at these: https://github.com/async-rs/async-std/tree/main/examples

In fact, there are a lot of crates in Rust where in other programming languages, it would be included in the standard library. Examples are regex, random number generators, additional iterator methods, macros for other collections, num traits, loggers, HTTP libraries, error handling, async runtimes, serialization and deserialization, date and time, and many more.

Two major projects (non std lib but extremely commonly used) stand out in the area of async programming: Async std and Tokio - no doubt familiar to anyone that has turned an eye towards Rust for a second too long. Async architecture in general is likely very familiar to JavaScript programmers but in Rust there are some extra considerations (like ownership of the data that is thrown into an async function). Tokio is fast becoming a heavily supported and road tested async framework, with a thread scheduling runtime "baked in" that has learned from the history of Go, Erlang, and Java thread schedulers.

Ah... https://github.com/tokio-rs/tokio and https://github.com/async-rs/async-std ?

async-std: Basically a Tokio alternative with a few different design decisions.

Go's solution is for the scheduler to notice after a while when a goroutine has blocked execution and to shift goroutines waiting their turn to another thread. async-std pondered a similar approach with tasks, but it proved controversial and was never merged.

This indicates curl, zlib, openssl, and libnghttp2 as well as a bunch of WASM-related things are being dynamically linked into my executable. To resolve this, I looked at the build features exposed by surf and found that it selects the "curl_client" feature by default, which can be turned off and replaced with "h1-client-rustls" which uses an HTTP client backed by rustls and async-std and no dynamically linked libraries. Enabling this build feature removed all -sys dependencies from androidx-release-watcher, allowing me to build static executables of it.

And also, the actual PR never got merged.

Async in rust needs a runtime (aka executor) to run. You can maybe get a better description from the rust docs. As an example, Tokio attempts to provide an interface for a developer that is minimal change to the more common blocking code. So you'd end up putting #[tokio::main] above your main function to spin up the executor and most of the rest of the code is similar to a non-async version with a few sprinkles of .await, which you can see in the hello world for tokio. In contrast, async-std provides a more hands-on/low-level approach. If you are unlucky enough to have libraries that choose different stacks to work on, you'll possibly (probably?) have to handle both.