Distributed Latency Profiling through Critical Path Tracing

Low latency is an important feature for many Google applications such as Search, and latency-analysis tools play a critical role in sustaining low latency at scale. For complex distributed systems that include services that constantly evolve in functionality and data, keeping overall latency to a minimum is a challenging task. In large, real-world distributed systems, existing tools such as RPC telemetry, CPU profiling, and distributed tracing are valuable to understand the subcomponents of the overall system, but are insufficient to perform end-to-end latency analyses in practice. Scalable and accurate fine-grain tracing has made Critical Path Tracing the standard approach for distributed latency analysis for many Google applications, including Google Search.