Avoid Large PRs... But Here's How to Manage Them if You Must

Pull requests (PRs) are crucial for integrating code changes. However, large pull requests can introduce several challenges that disrupt workflows and hinder project progress. Understanding these challenges and implementing team best practices can give teams the option to manage large PRs effectively.

Why You Should Avoid Large Pull Requests

Large pull requests are notoriously difficult to review. The sheer volume of changes makes it hard for reviewers to comprehend the full scope, leading to missed issues and less thorough reviews. Smaller PRs, in contrast, are more manageable and allow for detailed scrutiny, ensuring higher code quality. Additionally, large PRs increase the risk of bugs. With many changes bundled together, it's easier for bugs to slip through, and pinpointing their source becomes more challenging. By keeping PRs small, teams can test and validate individual changes more effectively.

Maintenance and rollback also become more complex with large PRs. If something goes wrong, reverting a large PR can be risky and time-consuming, potentially disrupting other ongoing work. Smaller PRs, however, are easier to manage and roll back if necessary. Another issue is delayed feedback. Large PRs require extensive review time, slowing down the development process and delaying valuable feedback. Regular, smaller PRs keep the feedback loop short, enhancing agility and responsiveness.

Effective Communication for Large PRs

Despite the challenges, large PRs can be managed successfully through several strategies. Effective communication is key, with detailed descriptions and annotated code to help reviewers understand changes. Regular updates and meetings ensure everyone is on the same page regarding the PR's progress and potential issues. Clear guidelines and standards streamline the review process, making it easier for reviewers to focus on critical aspects. Additionally, breaking down the PR into logical commits or smaller related PRs can mitigate many challenges, making it easier to review and test individual parts. Utilizing automated testing and continuous integration (CI) tools can catch issues early and maintain codebase stability. Commitment from all team members, coupled with good communication, ensures high code quality regardless of the PR size.

• • Determine Team Members: Identify who will work on the PR, including developers, reviewers, and any additional stakeholders. When speaking directly to the project leads and deciding who will manage this task, I like to ask these three questions to the senior team: 'Who wants to take on this task?', 'Who knows they can do this?', and 'Who is up to the challenge?'
• • Set a Schedule: Define a timeline for completing the PR, including key milestones and deadlines. A timeline will help leadership break the work into manageable pieces and integrate each piece into their current/pre-existing list of priorities. Milestones also provide a fun reason to celebrate progress and reflect on lessons learned, which can help in planning future tasks.
• • Organize Meetings: Schedule regular meetings to discuss the PR's progress, challenges, and next steps. Weekly progress updates may be sufficient, with ad-hoc meetings as needed. This is a great time to introduce document changes or team process changes, updates in coding standards/practices, and branch management strategies.
• • Break Down the PR: Divide the PR into smaller, logical commits or related smaller PRs. Each commit should represent a discrete piece of functionality or change, and hopefully, represent an easily testable integration point. This mitigates one of the biggest challenges with large branches: 'who did it?' A detailed PR description will help track the motivation and reasons behind the change.
• • Detailed Descriptions: Provide comprehensive descriptions for each PR. Clearly outline the purpose, scope, and key changes.
• • Annotate Code: Add comments on the PR to explain complex or non-obvious changes. This helps reviewers grasp the rationale behind each change, decide on testing strategies, and possibly strategize on how their contributions might fit in.
• • Document Changes: Maintain thorough documentation accompanying the PR. Include the rationale behind decisions, expected impacts, and relevant technical details. This serves as a permanent and company-wide way to communicate your work to everyone, including future engineers and management.
• • Regular Updates: Keep the PR updated with the current status and any new changes or fixes. This helps to make sure the team is all seeing the same thing and working with the latest changes with minimal effort and hassle to contributors.
• • Collaborative Review: Use pair programming for development and review. Involve multiple reviewers with different expertise to ensure comprehensive feedback. Hear it from the horses mouth: 'How did you envision integration with ...?', 'What did you intend with this bit of code?'
• • Automated Testing: Ensure automated tests are run frequently, addressing any issues immediately. Use CI tools to automatically test and build the project whenever changes are made. This will give confidence to any concerned parties who may be following along with the project.
• • Adhere to Standards: Follow consistent coding standards and guidelines to ensure readability and maintainability. Use a review checklist to cover all aspects of the PR. Establishing and following defined team best practices will help relieve ambiguity among contributors.

While large pull requests pose significant challenges and are advised against, they can be managed effectively through strategic planning and committing to team best practices. By clearly communicating and breaking down changes or updates, teams can ensure that their development process remains efficient, agile, and productive, even when dealing with extensive code changes.