async/await. Where is continuation of awaitable part of method performed?

Question

I am really curious how async/await enables your program not to be halted. I really like the way how Stephen Cleary explains async/await: \"I like to think of \"await\"

Answer 1

In general the continuation (the part of your method after await) can run anywhere. In practice it tends to run on the UI thread (e.g. in a Windows application) or on the thread pool (e.g. in an ASP .NET server). It can also run synchronously on the caller thread in some cases ... really it depends on what kind of API you're calling and what synchronization context is being used.

The blog article you linked does not say that continuations are not run on thread pool threads, it merely says that marking a method as async does not magically cause invocations of the method to run on a separate thread or on the thread pool.

That is, they're just trying to tell you that if you have a method void Foo() { Console.WriteLine(); }, changing that to async Task Foo() { Console.WriteLine(); } doesn't suddenly cause an invocation of Foo(); to behave any differently at all – it'll still be executed synchronously.