Speeding up code review with `small-change`

Imprint's engineers are now merging four times more pull requests (PRs) than two years ago. Among this growth, two teams have merged ten times more PRs than their peers two years ago. For instance, one engineer now merges 25 PRs per week compared to the average engineer two years ago. This surge in PRs has led to a 42% decrease in incidents and a whopping 78% drop in critical incidents. While the team acknowledges that the quality/velocity tradeoff is no longer a useful construct, the improved quality is undeniable.

However, the team has faced challenges with the review process, particularly with pull request reviews. Two years ago, a PR review took about 33 minutes, but now it takes around 77 minutes. The team decided to tackle this issue and introduced the "small-change" review process. This approach addresses the four main reasons for reviewing PRs.

The "review-pr-cluster," which reviews batches of PRs, has identified common themes and suggested ways to discuss and add verifications. This method has been implemented quickly and aims to expand the percentage of small-changes that can be approved fast.

The "small-change" review process simplifies the review by only providing an approval or ignoring the PR, avoiding the "meat proxy review" which acts as a bottleneck. The team believes that finding narrow and contained ways to validate new practices is the key to moving fast. They plan to continuously iterate and improve the verification mechanisms to handle the high scale-complexity and low domain-complexity software. Although the results are early, the core concept of the small-change review process is showing promise.