Timo Tijhof – [[WM:TECHBLOG]]

Flame graphs arrive in WikimediaDebug

The new “Excimer UI” option in WikimediaDebug generates flame graphs. What are flame graphs, and when do you need this?

Around the world: How Wikipedia became a multi-datacenter deployment

Learn why we transitioned the MediaWiki platform to serve traffic from multiple data centers, and the challenges we faced along the way.

Long exposure of highway with downtown skyscraper in the background of an unidentified city. There are green grass hills on both sides and a bright moon in the sky.

Perf Matters at Wikipedia in 2016

Looking back at our ups and downs.

Web Perf Hero: Valentín Gutierrez

Today we celebrate two numbers: 25% lower latency for ATS backend requests at the p75, and up to 1000X reduction of ATS disk read latency at the p999.

A graph of SPDY usage vs time to first paint

HTTP/2 performance revisited

Deploying HTTP/2 support to the Wikimedia CDN significantly changed how browsers negotiate and transfer data during the page load process. We found regressions in performance during the transition and are sharing the lessons we learned.

Profiling PHP in production at scale

We built an efficient sampling profiler for PHP. It runs continually in production on live requests, and generates trace logs and flame graphs.

WikimediaDebug v2 is here!

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.

Wikipedia’s JavaScript initialisation on a budget

This week saw the conclusion of a project that I’ve been shepherding on and off since September of last year. The goal was for the initialisation of our asynchronous JavaScript pipeline (at the time, 36 kilobytes in size) to fit within a budget of 28 KB – the size of two 14 KB bursts of Internet packets.