Testing Encyclopedias in Production

Tuesday, December 08, 2020 - 10:00 am10:40 am

Effie Mouzeli and Giuseppe Lavagetto, Wikimedia Foundation


At Wikimedia, we are running one of the top 15 traffic websites on the internet! Our infrastructure is powered by free software, with MediaWiki at its core. To improve performance, in 2014 we happily migrated from mod-php to Facebook's HHVM (Hip Hop virtual machine), and everything was well until September 2017: when Facebook announced that it would be dropping PHP support.

This is the story of the long project to migrate our application clusters from HHVM to php-fpm, and the application itself from PHP5 to PHP7, while serving billions of page views per month. We want to share the good, the bad, the ugly, and the questionable decisions we made in order to successfully migrate and give the SRE perspective of a complex migration, broken down into small pieces. Moreover, the centerpiece of this talk is how we benefited from testing in production, which played a key role during this project.

Effie Mouzeli, Wikimedia Foundation

Effie studied physics and distributed scientific computing but didn't turn out to be a physicist or a scientific computer scientist. She has worked as a systems engineer/SRE at a number of startups and small organizations (most of which are not with us anymore), where her responsibilities were usually automation, infrastructure architecture, and working closely with developers. Currently, she is on the SRE team that takes care of Wikipedia and its sister projects at the Wikimedia Foundation.

Giuseppe Lavagetto, Wikimedia Foundation

Giuseppe is an astrophysicist turned wannabe technologist. He has worked for the last 12 years on the infrastructure of large-scale websites, and for the last 6 on the infrastructure of your favourite free encyclopedia.

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@inproceedings {262208,
author = {Effie Mouzeli and Giuseppe Lavagetto},
title = {Testing Encyclopedias in Production},
booktitle = {SREcon20 Americas (SREcon20 Americas)},
year = {2020},
url = {https://www.usenix.org/conference/srecon20americas/presentation/mouzeli},
publisher = {USENIX Association},
month = dec

Presentation Video