How Google does code review

Google employs two internal code review tools, Critique and Gerrit, to manage and streamline their code review process. Critique, primarily used internally, features a customizable dashboard to track in-flight changes, while Gerrit, open-sourced for public projects like Chromium and Android, provides a detailed overview of change lists. Both tools offer unique functionalities such as test coverage metrics, commit message as a reviewable entity, and visual differentiation for moved code lines. A distinctive aspect of Google's code review is the "attention set," which indicates whose action is needed to progress a change list. To ensure high standards, changes must pass three levels of approval: LGTM, code owners, and a Google-specific readability review. Google's rigorous review process emphasizes not only functionality but also adherence to coding standards and best practices, contributing to a culture where code review is prioritized and thoroughness is valued, resulting in a median review time significantly shorter than industry averages.