We built an efficient sampling profiler for PHP. It runs continually in production on live requests, and generates trace logs and flame graphs.
WikimediaDebug is a set of tools for debugging and profiling MediaWiki web requests in a production environment. WikimediaDebug can be used through the accompanying browser extension, or from the command-line. This post highlights changes we made to WikimediaDebug over the past year, and explains more generally how its capabilities work.
Here is how we measure and interpret load times on Wikipedia. Let’s also look at what real-user metrics are, and how percentiles work.