Over the course of nearly a year, we migrated Pinterest’s primary systems from Python2 to Python3. A large, tightly coupled codebase with over 2 million lines of code, the Pinterest codebase contained nearly every edge case that might exist in a Py2 to Py3 migration. We’ll cover our approach, gotchas, and tools, and the incredible impact our migration has made on infra spend and code quality. Slides can be found at: https://speakerdeck.com/pycon2019 and …