I'm not super sure what was meant here, but I could add one point of info, FWIW: Go is creating extra OS threads for blocking system calls. In fact, sometimes m

I'm not super sure what was meant here, but I could add one point of info, FWIW: Go is creating extra OS threads for blocking system calls. In fact, sometimes more than one thread per such (for taking care of stdin and stdout, I think). I have been able to create at least 4999 go-routines with blocking system calls though (Two OS threads were created per go-routine / syscall), so not a problem you will run into quickly.