What’s new with Robinhood, our in-house load balancing service
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 service’s fleet, which inevitably increased our hardware spend—a pricey and avoidable headache.
Robinhood solves these long-standing load balancing problems at Dropbox scale, across our entire global data center footprint. Last year, we introduced the latest iteration to Robinhood: By leveraging proportional–integral–derivative (PID) controllers, Robinhood can now more quickly and effectively manage load imbalances. This has not only improved the reliability of our infrastructure, but yielded significant hardware cost savings. And with an increase in AI workloads that power our latest intelligent features, effectively managing demands on our GPU resources is more critical to the business than ever.
Our in-house service discovery system can scale to hundreds of thousands of hosts across multiple data centers around the globe. Some Dropbox services have millions of clients; however, we cannot allow each client to create connections to every server instance. This approach puts too much memory pressure on servers, and TLS handshakes during server restarts can overwhelm servers. Instead, we can use a service discovery system, which gives each client a subset of servers to connect to.
