I could actually use some feedback when it comes to the design of the parallelism model for UVM. I have a few ideas but it's not my area of expertise, so I would welcome feedback and suggestions.

I have experience as a user, implementation is way over my head. Depending on the minimum host supported, you could only use lightweight threads or write a scheduler. IIRC, JVM started using its own thread implementation and later used the one provided by the host OS, when available.

Best of luck!

At the moment I have an event-driven system where you can set up callbacks and timers. It's not green threads but it makes it easy to have multiple different update events running at different rates, for example: https://github.com/maximecb/uvm/blob/main/ncc/examples/attac...

For parallelism I'd expect something like Cilk (or Rayon, which was inspired by it), where there's some syscalls for spawning and then joining on tasks, but the VM handles starting and managing the thread pool.

For concurrency it's a lot harder to make a good interface

> For concurrency it's a lot harder to make a good interface

Can you elaborate?