In my experience by far the most widespread solution for directing requests is randomly. Round robin is pretty popular. Everything more sophisticated than that

In my experience by far the most widespread solution for directing requests is randomly. Round robin is pretty popular. Everything more sophisticated than that is vanishingly rare outside of large organizations. Look in gRPC. What client side load balancers does it come with? Pick_first and round_robin. Weighted round robin has some traction but even in engineering groups with lots of experience and talent the complexity of measuring CPU rate utilization is underappreciated.