Code Reviewing in the Trenches: Challenges and Best Practices

Code review has been widely adopted by and adapted to open source and industrial projects. Code review practices have undergone extensive research, with most studies relying on trace data from tool reviews, sometimes augmented by surveys and interviews. Several recent industrial research studies, along with blog posts and white papers, have revealed additional insights on code reviewing “from the trenches.” Unfortunately, the lessons learned about code reviewing are widely dispersed and poorly summarized by the existing literature. In particular, practitioners wishing to adopt or reflect on an existing or new code review process might have difficulty determining what challenges to expect and which best practices to adopt for their development context. Building on the existing literature, this article adds insights from a recent large-scale study of Microsoft developers to summarize the challenges that code-change authors and reviewers face, suggest best code-reviewing practices, and discuss tradeoffs that practitioners should consider. This article is part of a theme issue on Process Improvement.