HOW GOOGLE MIGRATED BILLIONS OF LINES OF CODE FROM PERFORCE TO PIPER

Summary from the TLDR Web Dev newsletter

Google's source control system initially relied on a single Perforce server and faced scalability issues as the company grew. To address this, Google engineers developed Piper, a distributed source control system designed for massive scale. The migration from Perforce to Piper took over four years due to the deep integration of Perforce into Google's software ecosystem and the need to avoid disrupting production. However, the migration was successful and Piper is still used at Google today.