is a system-wide performance monitoring system in use at Badoo that is built on top of XHProf or its forks (Uprofiler or Tideways).
Live Profiler continually gathers function-level profiler data from production tier by running a sample of page requests under XHProf.
Live profiler UI
then aggregates the profile data corresponding to individual requests by various dimensions such a time, page type, and can help answer a variety of questions such as: What is the function-level profile for a specific page? How expensive is function "foo" across all pages, or on a specific page? What functions regressed most in the last day/week/month?
What is the historical trend for execution time of a page/function? and so on.