Cilk++

[Rein Halbersma]

But with Cilk you have access to a process number, let's say it's the thread ID although I don't remember what it's called. So you can tag each state with this and make the state copy only when you know that the state has been stolen by another processor or thread.

I think Cilk++ can do this with what is called a "reducer hyperobject": a variable with a local view per thread that is only copied/synced when actually needed.