Robinhood is the internal Dropbox load balancing service we deployed in 2020. It is responsible for routing all our internal traffic between servers to balance service load. Before we built Robinhood, most Dropbox services suffered from uneven load distribution among backends. Hardware differences throughout our fleet and the limitations of our prior load balancing algorithms led to reliability issues due to overloaded instances. In order to solve this problem, we often had to over-provision a s...