Win32 fibers would probably not be a good match for potential .NET fibers. From the link in my previous comment, they seem to allocate the stack of the same siz

Win32 fibers would probably not be a good match for potential .NET fibers. From the link in my previous comment, they seem to allocate the stack of the same size as regular OS threads, making them not appropriate for the use case of keeping thousands or more fibers around. > Runtimes that choose to roll their own green threads, like Go, and I guess now also Java, are effectively stating that their convenience is worth the inability to interface well with async code outside of their runtime. You'd still be able to interop with async code outside of runtime, you can still model the API as callbacks for the interop purposes where needed. But yes, interop has sam trade-offs. Which are, IMO, entirely correct trade-offs to make for Go, Java and .NET (and overwhelmingly so). But they are probably not for (as an example) Rust, according to it's goals.