XHProfLive: Continuous function-level performance stats from production

What this post added

This post introduces XHProfLive, a system for collecting and analyzing continuous function-level performance statistics from production. It addresses the need for near real-time, detailed performance data to pinpoint regressions. The post highlights the development of XHProf, a lightweight instrumentation-based callgraph profiler, and its integration into XHProfLive for aggregating and visualizing performance data. It also announces the open-sourcing of XHProf, making this powerful profiling tool available to the wider community.