In fast-paced software development, code is frequently updated, adjusted, and improved to meet evolving requirements and enhance functionality. However, not all the changes are signs of positive progress. Frequent changes to the same code without progress indicate requirements ambiguity, design flows, and developer struggles.
While it’s normal for developers to revisit and update code to improve efficiency or add functionality, identifying parts of the code that undergo frequent changes can help teams address potential problems early. This is where the code churn metric comes into play.
What Is Code Churn?
Code churn is a key software development metric that tracks how often code is modified, rewritten, and deleted after it’s been written. Code churn is considered healthy to some extent, as it indicates progress and improvement.
However, a high code churn value can signal deeper issues in your development process and code quality. Therefore, by tracking and monitoring code churn, the development team can find areas of concern and take proactive steps to increase the code stability, quality, and efficiency.
Why Does Code Churn Happen?
The code churn value can increase due to several reasons.
- Lack of skill and knowledge of the developers can lead to mistakes and inefficiencies in the code.
- Poor communication between the team and the client can make requirements unclear and doubtful.
- Poor design and architectural issues can increase the difficulty of maintaining, reading, or extending the code.
- Tight deadlines and a focus on quick delivery can lead to cutting corners and accumulating technical debt.
- Changes in project scope or priorities during development can lead to significant rework.
- Code that is too complex or not well-documented can confuse developers, leading to mistakes or misunderstandings.
Why Is High Code Churn a Problem?
High code churn often indicates that there are issues in the code and process that are being followed. Here are some common examples.
1. Ineffective Testing
Even though an organization has a testing process, many defects can go unnoticed. Those defects must be fixed repeatedly, which means the organization’s testing and review process has issues that need to be fixed.
2. Technical Debt
When there is high code churn, there is a possibility of technical debt being accumulated in the process. This happens when the team prioritizes speed over quality, leading to rushed solutions that require frequent revisions later.
3. Poor Design
Code churn analysis can highlight poor design and architecture issues in the code. For example, frequent changes to a class might indicate that it does not follow the single responsibility principle in SOLID and is handling too many tasks without focusing on one.
4. Complex and Unreadable Code
High churn can also suggest that the code is overly complex or poorly documented, making it difficult for developers to understand. This leads to mistakes, misunderstandings, and frequent rework.
How Do You Manage Code Churn?
Keeping code churn under control is essential to ensure a smooth development process. Here are a few best practices to follow.
1. Track and Measure
- Code churn metrics provide a qualitative way to manage code churn.
- They help to understand and identify the areas and processes that need to be improved to reduce unnecessary code changes.
- Tools like GitPrime, CodeClimate, and SonarQube calculate these metrics using defined code churn formulas.
- Churn Rate: Calculates the percentage of churn relative to the total lines of code in the codebase.
- Churn Density: Measures how concentrated the churn is within a specific module or file.
- Rework Ratio: The proportion of changes that are rework rather than new development.
2. Address Root Causes
- High code churn often stems from underlying issues in the development process.
- Refactor the code to follow best practices like SOLID principles and modular design, making it easier to maintain and extend.
- Ensure clear communication between the team and stakeholders to prevent misunderstandings and unclear requirements.
- Tools like Structure101 and ArchUnit assist in analyzing and improving software architecture.
3. Conduct Regular Code Reviews
- Regular peer reviews ensure the code meets quality standards and adheres to best practices. Platforms like Qodo support automatic PR reviews.
- Simplify and improve complex or legacy code to make it more understandable and less prone to errors.
4. Robust Testing
- Automate unit tests and integration tests to quickly identify and fix bugs.
- Integrate code changes frequently to minimize conflicts and ensure stability.
- Testing frameworks like JUnit, pytest, and Mocha can be used to automate unit testing.
- Tools like Jenkins, GitHub Actions, and CircleCI streamline testing in CI/CD pipelines.
Is Code Churn Always a Problem?
Code churn is not always a problem. It is natural and common to undergo revisions and updates to the code in the development process. For example, developers refining a feature based on user feedback or fixing bugs that emerge during testing is a healthy sign of the development process. These changes increase the system’s overall functionality, performance, and usability. Therefore, having this type of code churn is a positive sign of a well-maintained and evolving codebase.
However, rewriting the same code repeatedly without any progress could result in high code churn, which could be a significant issue in the future.
By tracking metrics, improving processes, and addressing root causes, teams can ensure efficient, high-quality software development while maintaining lower code churn.
