Why You Should Care About Pull Request Size + Best Practices

Introduction

Developers often face challenges when determining the optimal size for their pull requests. This can lead to inefficient code reviews, slower feedback cycles, and potential quality issues. 

Measuring pull request size holds the key for you to unlock smoother code reviews, faster feedback loops, and better overall project outcomes. It will also enable you to gauge the extent of code changes within a single request.

In this article, we will explore the intricacies of measuring pull request size and delve into its significance. You will be equipped with practical strategies to optimize your development process and elevate your code to new heights of excellence.

What is the pull request size

Pull request size is a software development metric that measures the amount of code changes made in a single pull request. It reflects the size or scope of the changes introduced by a developer.

The size of a pull request can have a significant impact on the development process. Large pull requests with extensive changes can be more challenging to review, comprehend, and test. They can introduce a higher risk of errors and conflicts with other parts of the codebase.

On the other hand, smaller pull requests are generally easier to understand and review. They allow for faster feedback cycles and make it simpler to isolate and fix issues.

It is advisable to keep pull requests small and focused, addressing a specific task or change. This approach promotes better collaboration, improves code quality, and reduces the time it takes to merge changes into the main codebase.

Benefits of improving pull request size

Improving  pull request size can have several benefits for your software development team and company as a whole. Here are five of them:

Enhanced review process

Smaller pull requests are easier to review and understand. By keeping the changes focused and concise, your reviewers can provide more targeted feedback. This leads to faster and more effective code reviews. In fact, you will reduce the chances of missing important issues or introducing bugs. It also encourages collaboration and knowledge sharing among team members.

Quicker feedback cycles

With smaller pull requests, you can significantly accelerate feedback loops. Your developers will receive prompt responses from reviewers. It will enable them to iterate and improve their code more rapidly. Shorter feedback cycles facilitate continuous integration and deployment, making it easier to identify and address issues early in the development cycle.

Reduced merge conflicts

Large pull requests can introduce conflicts with other changes made in parallel. By keeping pull requests small, the chances of merge conflicts decrease. This ensures smoother integration of changes and minimizes the effort required to resolve conflicts. Consequently, your development team can maintain a steady pace of progress and avoid time-consuming conflicts.

Improved code quality

Smaller pull requests promote better code quality. By focusing on smaller, independent units of work, your developers can maintain cleaner and more modular codebases. This reduces the risk of introducing bugs, enhances maintainability, and makes it easier to track down issues if they arise. Overall, smaller pull requests contribute to a healthier and more robust codebase.

Agile and incremental development:

Breaking down tasks into smaller pull requests aligns well with agile and incremental development methodologies. It will allow you to deliver value in smaller increments, enabling stakeholders to see progress more frequently. Smaller pull requests also offer greater flexibility, making it easier to adapt to changing requirements and iterate on features.

Risks of focusing on pull request size

While measuring pull request size can provide you with valuable insights, it's important that you are  aware of potential risks and limitations. Here are five risks to consider when basing decisions solely on pull request size results:

Oversimplification of complexity

Pull request size alone may oversimplify the complexity of changes. If you focus solely on size, you may fail to consider the intricacies of code modifications, dependencies, and overall system impact. Ignoring these aspects can lead to a false sense of simplicity and undermine the quality of decision-making.

Neglecting contextual factors

Pull request size does not capture the contextual factors surrounding a change. Each feature or bug fix may have unique considerations and challenges that are not reflected in size alone. Ignoring these contextual factors can result in suboptimal decisions and compromises that may negatively impact the product.

Disregarding code quality

Emphasizing pull request size as the primary metric can divert your attention from code quality. Developers may be incentivized to focus solely on making smaller changes without giving due importance to maintainability, scalability, and overall code cleanliness. This approach can lead you to technical debt and reduce the long-term viability of the codebase.

Potential fragmentation of work

Overemphasizing pull request size may encourage excessive fragmentation of work. Your developers might feel pressured to make smaller, isolated changes to meet size targets, disregarding the overall coherence and efficiency of the codebase. This fragmentation can impede holistic understanding, hinder collaboration, and introduce unnecessary complexity.

Ignoring user value

Measuring pull request size alone may overlook the ultimate goal of delivering value to users. While you can enhance the development process with smaller pull requests, the size metric does not directly correlate with the impact on end-users. Prioritizing size over user value may result in missed opportunities to address critical user needs and deliver impactful features.

How to measure pull request size?

Measuring pull request size will allow your team to assess the scope and impact of code changes. Let's explore this measurement method using an example:

Suppose a developer, Alice, is working on a new feature for a web application. She creates a pull request to merge her changes into the main codebase. To measure the pull request size, we can consider the following:

Number of files modified

Count the total number of files that Alice has modified in her pull request. For example, she may have made changes to five files, including HTML templates, CSS stylesheets, and JavaScript files.

Lines of code added/removed

Calculate the number of lines of code Alice has added or removed in her pull request. For instance, she added 150 lines of code and removed 50 lines of code across the modified files.

By combining these measurements, you can determine the overall pull request size. In this example, Alice's pull request has a size of 5 files modified, with a net addition of 100 lines of code.

<span class="colorbox1" fs-test-element="box1"><p> It's important to note that measuring pull request size is not limited to just files and lines of code. The complexity of the changes, the impact on system behavior, and other contextual factors should also be considered to gain a more comprehensive understanding. </p></span>

Alternatives to pull request size

While measuring pull request size can provide valuable insights, it's important to consider alternative approaches that complement or provide additional perspectives. Here are a few main alternatives to pull request size:

Code complexity analysis

Instead of focusing solely on the size of pull requests, your team can analyze the complexity of code changes. Tools like cyclomatic complexity metrics or static code analysis can help evaluate the intricacy and potential risks associated with modifications. This approach provides a deeper understanding of the impact on code quality and maintainability. 

<span class="colorbox1" fs-test-element="box1"><p>Choose code complexity analysis when you seek to assess the intricacy and potential risks of code changes beyond their size. </p></span>

Test coverage

Evaluating the test coverage associated with pull requests offers an alternative perspective. It measures the extent to which the modified code is covered by automated tests. Higher test coverage indicates more confidence in the changes and reduces the risk of regressions. Test coverage analysis helps ensure code quality and stability. 

<span class="colorbox1" fs-test-element="box1"><p> Opt for test coverage evaluation when prioritizing the reliability and resilience of code changes. </p></span>

User value and impact

Assessing the user value and impact of pull requests focuses on the value they bring to end-users or the business. It involves considering factors like user feedback, customer requests, or business goals. By prioritizing value-driven changes, your team will ensure that their efforts align with the needs and expectations of stakeholders. 

<span class="colorbox1" fs-test-element="box1"><p> Choose user value and impact analysis when prioritizing features or changes based on their direct impact on users or business objectives. </p></span>

Peer review feedback

Instead of relying solely on metrics, your team can emphasize the feedback and insights provided during peer code reviews. Human judgment and expertise play a crucial role in evaluating code changes. Peer reviews provide an opportunity for knowledge sharing, identifying potential issues, and enhancing overall code quality. 

<span class="colorbox1" fs-test-element="box1"><p> Leverage peer review feedback when seeking a comprehensive evaluation that incorporates human insights and expertise. </p></span>

Next steps

Measuring pull request size provides teams with valuable insights into the magnitude of changes introduced. It helps assess the review effort required, potential risks, and the impact on the codebase. By tracking and analyzing pull request sizes, teams can optimize their development processes, promote collaboration, and deliver high-quality software products efficiently. However, metrics should always be adjusted to product and business goals, and every team should compose a set of metrics that works best for their specific case.

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To learn more about a variety of metrics, check out our articles and start building a comprehensive set of metrics for your product today.