Flee VS runtimelab

If I understand it correctly, can it replace this library ?

Off the top of my head, NCalc, Jace, and Flee. Probably others, but these are the ones I know of.

For everyone reading this blog post I caution that the conclusions there are at best creative interpretations of the notes written down here: https://github.com/dotnet/runtimelab/blob/feature/async2-exp...

It is quite literally impossible to draw conclusions on e.g. memory consumption until the work on this, which is underway, makes it into mainline runtime. It's important to understand that the experiment was first and foremost a research to look into modernizing async implementation, and was a massive success. Now once that is proven, the tuned and polished implementation will be made.

Once it is done and makes into a release (it could even be as early as .NET 10), then further review will be possible.

This FAQ is a bit outdated in places, and is not something most users should worry about in practice.

JVM Green Threads here serve predominantly back-end scenarios, where most of the items on the list are not of concern. This list also exists to address bad habits that carried over from before the tasks were introduced, many years ago.

In general, the perceived want of green threads is in part caused by misunderstanding of that one bad article about function coloring. And that one bad article about function coloring also does not talk about the way you do async in C#.

Async/await in C# is just a better model with explicit understanding where a method returns an operation that promises to complete in the future or not, and composting tasks for easy (massive) concurrency is significantly more idiomatic than doing so with green threads or completable futures that existed in Java before these.

Also one change to look for is "Runtime Handled Tasks" project in .NET that will replace Roslyn-generated state machine code with runtime-provided suspension mechanism which will only ever suspend at true suspension points where task's execution actually yields asynchronously. So far numbers show at least 5x decrease in overhead, which is massive and will bring performance of computation heavy async paths in line with sync ones: https://github.com/dotnet/runtimelab/blob/feature/async2-exp...

Async/await is not a tight corner as showcased by a multitude of languages adopting the pattern: Rust, Python, JavaScript and Swift.

In fact, it is a clean abstraction where future progress is possible while retaining the convenience of its concurrency syntax and task composition.

Green threads experiment proved net negative in terms of benefit but its the follow-up work on modernizing the implementation detail was very successful: https://github.com/dotnet/runtime/issues/94620 / https://github.com/dotnet/runtimelab/blob/feature/async2-exp...

It also seems that common practices in Java indicate that properties are not a mistake as showcased by popularity of Lombok and dozens of other libraries to generate builders and property-like methods (or, worse, Java developers having to write them by hand).

There was a "green thread" experiment for dotnet a while ago, here is the conclusion: https://github.com/dotnet/runtimelab/issues/2398

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.

Yeah, it kind of is. There are quite a few of experiments that are conducted to see if they show promise in the prototype form and then are taken further for proper integration if they do.

Unfortunately, object stack allocation was not one of them even though DOTNET_JitObjectStackAllocation configuration knob exists today, enabling it makes zero impact as it almost never kicks in. By the end of the experiment[0], it was concluded that before investing effort in this kind of feature becomes profitable given how a lot of C# code is written, there are many other lower hanging fruits.

To contrast this, in continuation to green threads experiment, a runtime handled tasks experiment[1] which moves async state machine handling from IL emitted by Roslyn to special-cased methods and then handling purely in runtime code has been a massive success and is now being worked on to be integrated in one of the future version of .NET (hopefully 10?)

[0] https://github.com/dotnet/runtime/issues/11192

[1] https://github.com/dotnet/runtimelab/blob/feature/async2-exp...

Unlike these folks from dotnet, which tested directly on ASP for real workload

  https://github.com/dotnet/runtimelab/issues/2398?darkschemeovr=1

[1] https://github.com/dotnet/runtimelab/issues/2398

The only way to avoid it is to not build on top of Java or not adding any features on top of Java.

> To give another example with C#, there has been a lot of recent discussion about finding potential alternatives to their async-await concurrency model. They cite the level of effort it takes to maintain the async await style code and the costs that come from this.

I had a very different take-away. They did PoC with virtual threads and decided it's not worth the switch now and async-await that they have is good enough.

https://github.com/dotnet/runtimelab/issues/2398

> Some of the languages it gets compared too aren't even that old yet.

C# is old enough to drink and Scala just had its 20th birthday this week :)