[jelambs]

Author here, that’s a great question! We approach this by ensuring that there are always multiple people that can review a given codebase or service. In practice what this looks like is we have teams that own our different services. Rather than just assign a random person from that team if you’re making a PR for one of their services, we utilize what we call “open” slack channels, where any one can ask questions of the team. So you’ll go to the teams’s slack and ask for someone to review. We recommend @ mentioning the people who’ve most recently made significant changes to the code you’re working in as they’re most likely to be the best reviewers. But by sharing the responsibility across each team, that ensures there’s no piece of code that only one person across the whole engineering organization is qualified to review. For projects within a team, there will generally be one or two dedicated reviewers and we utilize stand ups to check in and make sure no one is overloaded with reviews. And since the whole team has familiarity with the project, it’s easy to swap out a reviewer if someone is overwhelmed or on vacation.