Why choose async/await over threads?

• FrameworkBenchmarks

  366 7,384 9.8 Java

  Source for the TechEmpower Framework Benchmarks project

  

Eh. Async and to a lesser extent green threads are the only solutions to slowloris HTTP attacks. I suppose your other option is to use a thread pool in your server - but then you need to but hide your web server behind nginx to keep it safe. (And it is safe because uses async IO).

Async is also usually wildly faster for networked services than blocking IO + thread pools. Look at some of the winners of the techempower benchmarks. All of the top results use some form of non blocking IO. (Though a few honourable mentions use go - with presumably a green thread per request):

https://www.techempower.com/benchmarks/

I’ve also never seen Python or Ruby get anywhere near the performance of nodejs (or C#) as a web server. A lot of the difference is probably how well tuned v8 and .net are, but I’m sure the async-everywhere nature of javascript makes a huge difference.

• may

  17 1,720 8.2 Rust

  rust stackful coroutine library

https://github.com/Xudong-Huang/may

The project has some serious restrictions and unsound footguns (e.g. around TLS), but otherwise it's usable enough. There are also a number of C/C++ libraries, but I can not comment on those.

• WorkOS

  workos.com sponsored

  The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.

  

• .NET Runtime

  607 14,091 10.0 C#

  .NET is a cross-platform runtime for cloud, mobile, desktop, and IoT apps.

  

We might not be that far away already. There is this issue[1] on Github, where Microsoft and the community discuss some significant changes.

There is still a lot of questions unanswered, but initial tests look promising.

Ref: https://github.com/dotnet/runtime/issues/94620

• cargo-call-stack

  5 554 0.0 Rust

  Whole program static stack analysis

Yes, it's what I wrote about in the last paragraph. If you can compute maximum stack size of a function, then you can avoid dynamic allocation with fibers as well. You are right that such implementations do not exist in right now, but I think it's technically possible as demonstrated by tools such as https://github.com/japaric/cargo-call-stack The main stumbling block here is FFI, historically shared libraries do not have any annotations about stack usage, so functions with bounded stack usage would not be able to use even libc.

• samsara

  6 64 10.0 Rust

  a reference-counting cycle collection library in rust

> Just for example: "it needs a GC" could be the heart of such an argument

Rust can actually support high-performance concurrent GC, see https://github.com/chc4/samsara for an experimental implementation. But unlike other languages it gives you the option of not using it.

• embassy

  70 4,377 9.9 Rust

  Modern embedded framework, using Rust and async.

  

thanks. looked that up. for the curious: https://embassy.dev/

• dazzlefruit

  1 2 7.7 Rust

[2] https://github.com/DanielCausebrook/dazzlefruit/blob/master/...

• InfluxDB

  www.influxdata.com sponsored

  Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.

  

• runtimelab

  52 1,331 4.6

  This repo is for experimentation and exploring new ideas that may or may not make it into the main dotnet/runtime repo.

  

Experiment result write-up: https://github.com/dotnet/runtimelab/blob/e69dda51c7d796b812...

TLDR: The green threads experiment was a failure as it found (expected and obvious) issues that the Java applications are now getting to enjoy, joining their Go colleagues, while also requiring breaking changes. It, however, gave inspiration to subsequent re-examination of current async/await implementation and whether it can be improved by moving state machine generation and execution away from IL completely to runtime. It was a massive success as evidenced by preliminary overhead estimations in the results.

• asyncly

  2 27 4.6 C++

  C++ concurrent programming library

  

One of the main benefits of async/await in Rust is that it can work in situations where you don't even have threads or dynamic memory. You can absolutely use it to write very concise code that's waiting on an interrupt on your microcontroller to have read some data coming in over I2C from some buffer. It's a higher level abstraction that allows your code to use concurrency (mostly) without having tons of interactions with the underlying runtime.

Every major piece of software that I have worked on has implemented this in one form or another (even in non-modern C++ where you don't have any coroutine concepts, Apple's grand central dispatch,). If you don't then your business logic will either be very imperformantly block on IO, have a gazillion of threads that make development/debugging a living hell, or be littered with implementation details of the underlying runtime or a combination of all 3.

If you don't use existing abstractions in the language (or through some library), you will end up building them yourselves, which is hard and probably overall inferior to widely used ones (if there are any). I have done so in the past, see https://github.com/goto-opensource/asyncly.

Suggest a related project