hyperia VS tokio

This actually can be at the level of a missed optimization. A run queue with a lock-shared queue amongs all the threads scales even worse than the tokio version. Sharding the run queues and changing the notification algorithm, even while keeping locks on the sharded queues improves throughput drastically.

Tokio is an async runtime, but I don't see why being an async runtime should make it worse from a throughput perspective for a thread pool. I actually started on a Rust version [0] to test out this theory of whether async-rust was the culprit, but realized that I was being nerd-sniped [1] at this point and I should continue my Zig work instead. If you're still interested, I'm open to receiving PRs and questions on that if you want to see that in action.

It's still correct to benchmark and compare tokio here given the scheduler I was designing was mean to be used with async tasks: a bunch of concurrent and small-executing work units. I mention this in the second paragraph of "Why Build Your Own?".

The thread pool in the post is meant to be used to distribute I/O bound work. A friend of mine hooked up cross-platform I/O abstractions to the thread pool [2], benchmarked it against tokio to be have greater throughput and slightly worse tail latency under a local load [3]. The thread pool serves it's purpose and the quicksort benchmark is to show how schedulers behave under relatively concurrent work-loads. I could've used a benchmark with smaller tasks than the cpu-bound partition()/insertion_sort() but this worked as a common example.

I've already mentioned why rayon isn't a good comparison: 1. It doesn't support async root concurrency. 2. scoped() waits for tasks to complete by either blocking the OS thread or using similar inline-scheduler-loop optimizations. This risks stack overflow and isn't available as a use case in other async runtimes due to primarily being a fork-join optimization.

[0]: https://github.com/kprotty/zap/blob/blog-rust/src/thread_poo...

[1]: https://xkcd.com/356/

[2]: https://github.com/lithdew/hyperia

[3]: https://gist.github.com/kprotty/5a41e9612657de00788478a7dde4...

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).