Running Consistent Applications Closer to Users with Radical for Lower Latency

Running applications close to users—in nearby datacenters, at edge points of presence, or in on-premises clusters—is attractive, as it reduces end-to-end latency. Moving strong consistent applications closer to users is difficult, as they incur high latencies either when accessing, or coordinating, their storage system. This restricts such applications to running co-located with their data, in a datacenter. Radical allows these applications to leverage the latency benefits that come from running near users. Radical uses its new LVI protocol to perform all necessary coordination in a single request. This request guarantees linearizability with a combination of locks, a validation step, and write intents. Radical hides the latency of the LVI request by overlapping it with speculative execution of the application. Our evaluation shows that Radical achieves 84–89% of the latency improvement obtainable by moving out of the datacenter, while providing Linearizability.