And almost a decade earlier, in the context of private cloud, was implemented in Sun's Niagara line of processors: https://en.wikipedia.org/wiki/UltraSPARC_T1

The UltraSPARC T1 was designed from scratch as a multi-threaded, special-purpose processor, and thus introduced a whole new architecture for obtaining performance. Rather than try to make each core as intelligent and optimized as they can, Sun's goal was to run as many concurrent threads as possible, and maximize utilization of each core's pipeline.