Dead and unused code can clutter your Java applications, slow performance, and increase maintenance costs. Dead code is executed but its results aren’t used, while unused code is never called at all—often remnants of old features or unreachable paths. Both types bloat your codebase and introduce technical debt. Regular testing, code reviews, refactoring, and feature flags help reduce this clutter. Azul Intelligence Cloud’s Code Inventory tool identifies unused code in production, giving developers visibility into what can safely be removed—streamlining maintenance, improving performance, and freeing teams to focus on building valuable new features.
What Is Dead and Unused Code?
When dealing with technical debt and maintaining code, you’re going to encounter dead code and unused code. Dead code is code that isn’t being used by your application. There should be no consequences to your application if you remove it. In fact, you’ll significantly reduce the burden of code maintenance, making it easier to understand your code. You’ll also have less code to test and maintain, which should provide a boost to your Java efficiency. See the webinar, Your Undead Code Is A Time Vampire.
Then what’s unused code, and how is it different from dead code?
Dead code is written and included in your application. It’s usually executed, but the results are never used either because the results are redundant (other code already completed the task), or the results are no longer needed by the rest of the program.
Unused code is also sometimes called unreachable code. This code, including functions variables, etc, is written but not called or referenced anywhere in the program. Unused code might not be executed due to conditional statements or similar logical conditions that never allow the code to run. Unused code could also be for features that were never deployed (or are no longer being used). It can end up bloating your codebase, which will make it harder to manage.
Both types of code lead to wasted CPU performance, maintenance challenges, and confusion (as new developers might waste time trying to figure out why it’s there). You can remove both types to improve the clarity and efficiency of your application.
Codebase maintenance can be very costly when your codebase is riddled with dead or unused code because it requires more developer hours to manage. You’ll want to free up those resources so that your development team can create new features and improve your product. The risk of bugs and unsecure code is increased based on the size and complexity of your codebase. A poorly structured or maintained codebase can lead to unreliable software and poor user experience. As the codebase grows, it becomes increasingly difficult to identify and resolve issues with dead and unused code, but there are tools and techniques that can help.
How Do You Remove and Reduce Dead and Unused Code?
IDEs won’t provide the insights you need to identify and remove dead code, and profilers can become so intensive that you might not be able to use them in production. Also, some build tools allow you to configure them to exclude unused code during the build process, but the code itself would still remain in the source-code repository. Ultimately, some type of code analysis will be necessary to identify dead and unused code.
For preventing and identifying dead and unused code, you can follow some best practices when creating or refining your Java applications:
- Automated testing is used for comprehensive unit testing and integration testing. Use this method to ensure all your code is being used.
- Code reviews with peer developers helps identify and remove unnecessary code. With diverse perspectives, a lot of help, and fresh eyes, many of these issues can be identified. For example, someone who hasn’t seen the code is more likely to question what it’s doing than someone who wrote the code.
- Refactoring in a regular cadence will help you refine the structure and readability of your code over time. You’re also far more likely to find redundant or unneeded code.
- Version control is used to flag and subsequently safely remove code, knowing that you can just revert your code back to a previous version, as needed. One method is to use Git to track your changes.
- Feature flags can be used to control the activation of specific code paths. This helps you identify deprecated or unused features so that you can remove the associated code.
- Documenting your code can help you (and your team) question what the code is doing, meaning you’re more likely to find the unused and dead code.
How Azul Intelligence Cloud Intelligence Addresses Dead and Unused Code
Azul Intelligence Cloud (IC) provides you with actionable intelligence and insights from your production Java runtime data. You can effectively prioritize vulnerable code that needs to be addressed, and you can identify unused code for removal. IC works with any JVM from any vendor or distribution.
You can use Code Inventory to identify and remove unused code in Java applications. Code Inventory catalogs your code that’s running in production across all your Java workloads. It offers a code-use analysis, with detailed insights into how the code’s being used. This process provides you with visibility into unused code. You can then eliminate the unused and dead code, which greatly reduces your maintenance efforts.
