AsyncEx VS AspNetCoreDiagnosticScenarios

PS: You may want to look at the other in-memory concurrency structures available. You may find something that perfectly fits the specific problem you are trying to solve. https://learn.microsoft.com/en-us/dotnet/api/system.threading?view=net-7.0, https://learn.microsoft.com/en-us/dotnet/api/system.collections.concurrent?view=net-7.0, and https://github.com/StephenCleary/AsyncEx

Async Lock.

If you haven't seen it before, there's an excellent async util library on nuget by Stephen Cleary called Nito.AsyncEx.Coordination. It contains a number of classes to help with async synchronization, giving options beyond SemaphoreSlim. It might be worth checking out.

and if you need ReaderWriterLock behavior in an async context, Stephen Cleary has an implementation

Pessimistic concurrency - you can use something like AsyncLock from Nito.AsyncEx package, to lock around each db access.

This library has class that will allow you to safely run async code in Sync-context enabled environment.

Nito.AsyncEx:

This one is a pretty decent guide - https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/blob/master/AsyncGuidance.md

The C# (mostly applicat community has e.g. https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/blob/master/AsyncGuidance.md written by one of the Asp.Net architects. I found this in this lovely thread https://news.ycombinator.com/item?id=36785691 which expresses my views/confusion more clearly than I can express.

No it doesn't, hence why there are best practices guidelines written by the .NET architects, and there was a research project to add Go/Java co-routines as well.

https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/b...

https://twitter.com/davidfowl/status/1532880744732758018?lan...

https://github.com/dotnet/runtimelab/issues/2057

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

They don't work just fine in C#, there is a reason why one of ASP.NET architects has written a guide of best practices.

https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/b...

Many that praise async/await in C#, kind of forget it took about 10 years to spread across all the layer of the language and runtime, since it was done via IL rewriting, it caused several issues with F# async tasks, due to the age of the ecosystem plenty of code isn't async/await friendly and needs to be wrapped into Task.Run() or similar.

There is a best practices guideline from one of the ASP.NET architects, https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/b...

During last year they researched adding Go/Java's approach to .NET, but now it is too late. See the ASP.NET Q&A session at BUILD 2023.

The best guidance I have found was from here: AsyncGuidance.md

To expand upon this thought, here is the AsyncGuidance doc[1] on why not to use .Result to get the return value of a completed Task in C#.

To make this simple they introduced async Main[2] a few years ago.

[1]: https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/b...

Async Guidance