> Rather than a single, serialized scheduler, we run a fleet of scheduling servers which handle sandbox creation requests concurrently. To handle a creation request, a scheduling server runs a fast scheduling algorithm against in-memory cached data. The result is that scheduling scales horizontally, and looks more like load balancing than traditional container scheduling.

What does this mean? You bucket requests on some attribute and use that to route the request (or create an ordered list of routes to try)?

We make a probabilistic routing decision based on worker load and attributes of the sandbox request. I compare to a load balancer because it's essentially just forwarding an HTTP request.