Pull Request Size

Owned by Shir Koretski
Dec 20, 2024
3 min read

Managing Code Changes and Assessing Risk

Overview

Pull Request (PR) Size is an important metric that evaluates the magnitude of code changes within a pull request. It reflects how extensive the proposed changes are in terms of added, modified, or removed lines of code. Monitoring PR size is critical for identifying potential risks, as larger pull requests tend to be more complex, harder to review, and more prone to introducing bugs. By analyzing PR sizes, teams can better manage the balance between quality, review efficiency, and risk.

What Does This Metric Measure?

PR Size measures the volume of code changes made within a pull request. It is calculated based on the number of lines of code added, modified, or removed. The metric can provide insight into the scope of a PR, from small, incremental changes to larger, more substantial changes that affect multiple files or features. PR Size can indicate how much work is required to review and integrate the changes into the main codebase.

How Is This Metric Calculated?

PR Size is typically calculated by counting the number of lines of code (LOC) changed in a pull request. This includes:

  • Lines added: New lines of code that have been introduced.

  • Lines removed: Lines of code that have been deleted.

  • Lines modified: Lines of code that have been altered.

These counts are usually combined to give a total PR size. This can also be broken down into more specific categories, such as the number of files impacted or the types of changes made (e.g., refactoring vs. new features).

What Questions Can I Answer from This Data?

  1. How extensive are the code changes in each PR?
    By examining the total lines added, removed, or modified, you can determine the size of each PR and assess whether the changes are small and manageable or large and potentially risky. Large PRs may require more in-depth review and testing to avoid bugs or integration issues.

  2. Are there any trends in the size of PRs (e.g., very small vs. very large)?
    This data helps to identify whether your team typically submits small, focused PRs or larger, more comprehensive ones. Smaller PRs are generally easier to review and less prone to bugs, while larger PRs can signal complex changes that might introduce errors or require more review time.

  3. Has there been any noticeable trend in PR size over time?
    Tracking PR size over time helps to identify patterns. For example, you might see that PR sizes are growing, which could indicate that developers are taking on larger tasks or that the development process is changing. This could also highlight a shift in team practices or the complexity of features being developed.

What Should I Take Away from This Data?

  1. Trends Over Time
    Monitoring PR size trends can reveal whether the development process is becoming more efficient or the codebase is growing more complex. Consistently large PRs may indicate a need for better task breakdown and smaller, more frequent submissions.

  2. Distribution of Sizes
    The range of PR sizes offers insights into your team’s development practices. A dominance of small PRs suggests an efficient, incremental approach, while large PRs may signal a lack of task division or code modularity, pointing to opportunities for improvement.

  3. Risk Management
    Large PRs are riskier and harder to review, test, and integrate. Tracking PR size allows early identification of large PRs, enabling teams to break down tasks into smaller pieces and reduce integration risks.

  4. Improving Code Review Efficiency
    Large PRs can create bottlenecks. Encouraging smaller, well-defined PRs streamlines the review process, improves quality, and reduces integration issues.

Conclusion

Pull Request Size is a crucial metric for managing code changes and assessing potential risks. Tracking this metric helps identify trends, optimize workflows, and ensure smoother code reviews. Smaller PRs are easier to review and integrate, while larger ones may indicate the need for better task breakdown or additional resources. By monitoring PR size, you can improve development efficiency, reduce integration risks, and enhance team collaboration.