How the Wikimedia Foundation Successfully Migrated to PHP7

Effie Mouzeli, a Site Reliability Engineer (SRE) at the Wikimedia Foundation, discussed the steps taken to migrate Wikipedia from HVVM (HipHop Virtual Machine) to PHP7 while serving 100,000 requests per second and 17 billion page views per month. The migration involved cross-team collaboration, testing in production, and community support. Despite thorough pre-production testing, the team still encountered issues during live deployment, emphasizing the importance of testing in production to catch unforeseen user behavior.