Learning A Codebase - What I Learned After 4+ Years At Meta

Learning a massive codebase can be challenging, but new engineers are expected to become productive within a few months. Avoid excessive reading and overreliance on documentation; instead, adopt a hands-on approach, use debugging tools generously, and engage in pair programming. Focus on understanding the critical 20% of the codebase that has the most impact by consulting experts, analyzing code history, and monitoring code reviews. Small achievements, like mastering the release process and contributing to documentation, can build confidence and accelerate your learning curve.