Debugging in software development explained

Debugging is the art of identifying bugs and issues in software code to ensure a seamless and reliable user experience.

In this post, we’ll dive deeper into debugging and understand various types of debugging approaches you can use. You’ll also learn how to use debugging tools to troubleshoot your code more effectively.

What is debugging?

Debugging is the process of analyzing code or software to identify and detect bugs. A bug is anything that can cause unwanted behavior in a program.

In the life cycle of developing software, debugging is crucial at every step, from planning the software to developing it and releasing it for production. Typically, all types of software developers involved in the development and release of the software are responsible for debugging.

DevOps teams may also be responsible, depending on in which phase of the software life cycle debugging is needed. Moreover, dedicated QA (quality assurance) teams may also perform extensive debugging during the testing phase of the software before it’s released to the users.

Debugging is a crucial process for ensuring that you offer a seamless and reliable experience to your end users. It assists engineers and developers on your team in narrowing down the cause of a bug or an issue, which further helps in its timely resolution.

In the life cycle of developing software, debugging is crucial at every step, from planning the software to developing it and releasing it for production.

Types of debugging

There are several approaches one can take to effectively debug their code. Each approach has its benefits and works well with certain use cases.

Backtracking

Backtracking involves tracing the path of the occurrence of a bug to identify the source. Instead of checking directly in the code, you go backward from the bug to narrow down the part of the code that caused the bug.

Backtracking is useful in pinpointing what changes to a codebase caused a bug, and hence can be a great technique to debug any issues caused by recent code changes. For instance, if a specific release crashed an application, using backtracking, developers can narrow down the commit that likely caused the change.

Cause elimination

This technique is used to eliminate multiple plausible causes and is often helpful in situations where a bug could have many seemingly similar causes associated with it. Using cause elimination, you can methodically go through each possible cause and eliminate the ones that don’t seem relevant to the bug. This helps in isolating the root cause of the bug, which also simplifies resolution.

Consider a scenario where you’re trying to debug the cause of why your frontend application performs slower than expected. Using cause elimination, you can eliminate any database performance, API latency, or response times as possible causes and narrow down to a specific feature, page, or interaction on the client side that could be causing the performance issues.

Divide and conquer

You can use divide and conquer to break a specific part of your codebase into smaller and more manageable components. Each component can then be divided further, and the process goes on till you can narrow down the smallest piece of code that likely caused the bug.

This strategy is effective for complex and larger systems where bugs are difficult to trace due to lots of moving parts. For instance, if you’re trying to troubleshoot a memory leak in a backend application, you can break or divide your monolith into individual services, and then further divide or break these services into functions, and so on until you narrow down a single function that was causing the memory leak.

You can use divide and conquer to break a specific part of your codebase into smaller and more manageable components.

Print and log debugging

Using print statements and logging code outputs is the most straightforward type of debugging. Here, you can add print statements where you can print values of variables, their types, and also log timestamps and references to variables to narrow down the cause of a bug. This technique is most helpful in debugging runtime bugs in your application.

Rubber duck debugging

The rubber duck debugging technique is a classic technique to explain code, and in turn, dry run it by explaining it to an inanimate object, like a rubber duck. This technique is extremely helpful in situations where developers experience knowledge bias or mental fatigue during time-sensitive debugging sessions. It allows them to logically address mistakes in the code by verbalizing them.

For instance, a developer can use the rubber duck debugging technique to understand why the base case of a recursive code block can lead to an infinite loop bug that can cause the application to crash. A popular example of this is re-rendering a frontend component indefinitely due to state updates mistakenly set in an infinite loop.

Automated debugging

Automated debugging tools such as debuggers in terminals, integrated into IDEs, or debugger logs presented on the console or in the browser can be extremely helpful in initiating a debugging session where you’re unsure of which approach or technique to take, or for bugs where manual debugging techniques can be cumbersome to implement.

Brute force debugging

Brute force debugging involves checking every case or condition in a code block to identify which condition causes the bug. Due to its time-intensive nature, it’s often the last resort developers adopt when all other techniques fail. It can also be helpful for stubborn bugs that aren’t easily captured in a logical analysis or issues that occur without any general pattern.

Debugging process

Following a structured approach during debugging can help you reap the benefits of debugging effectively. The following steps can be performed as part of the debugging process.

Reproduce the issue

Before you can start debugging the issue, you need to experience it firsthand. You can reproduce the issue by replicating the exact conditions under which it occurs. Reproducing the issue gives you more clarity in understanding it, which can help in the subsequent steps of debugging as well. It may also induce empathy for your users, which can lead to a better resolution.

Identify the bug

Identifying the bug means locating precisely where the bug occurs. This step may be performed after or before you reproduce the issue. For instance, you can identify if the bug happens on the client side or server side, or which file it occurs in, which function it belongs to, etc. This step helps you narrow down the target code that you need to analyze for debugging.

Determine the root cause

The heart of debugging lies in determining the root cause. However, oftentimes, developers ask themselves, “How can I effectively identify the root cause of a bug in my code?”

Once you’ve identified the bug and successfully reproduced it, you can use one or more of the debugging techniques described in the previous section to determine the exact root cause of the bug. This step helps you understand why the bug occurs and will simplify the solution you choose for its resolution.

Choosing the right technique based on the debugging scenario and time constraints can greatly help in identifying the root cause of the bug.

Implement the fix

Determining the root cause gives you a clear sense of what you can do to fix the bug. In this step, you should think through possible fixes for resolving the bug and implement the fix that makes the most sense.

If you’re not directly involved in the resolution process, you can also share your possible solutions with the desired team to save time.

Validate the fix

Using the same conditions or test cases that led you to reproduce the bug, you should validate the fix to ensure the bug has been successfully resolved. You can also go beyond this and write any test cases to make the fix more foolproof or perform more thorough testing to ensure the fix doesn’t introduce a new bug of its own.

Document the process

Recording how and why the bug occurred, what debugging technique helped, the resolution selected, and so on can help deliver the relevant knowledge to other teammates. It can also act as a reference for future debugging processes.

Identifying the bug means locating precisely where the bug occurs.

What are the common tools used for debugging in software development?

The entire process of debugging can be simplified to a great extent using dedicated debugging tools. You should pick a debugging tool that you’re most familiar with and comfortable with, since using a tool that involves a learning curve can prolong the debugging process and delay the resolution.

The following are some of the common tools used for debugging by developers:

• IDEs: Visual Studio Code, Atom, and IntelliJ IDEA provide built-in debugging tools that you can use from within your codebase to inspect code and pinpoint errors.
• Debuggers: For client-side debugging, browsers offer a built-in debugger where you can pause and run your code based on a debugger line that you can add to your code. This helps with root cause detection by allowing you to focus on the specific lines of code that you suspect may be at fault.
• Logging Utilities: Logging tools provide detailed logs of your applications at both runtime and compile time. Moreover, logging functions, either custom built or open source, can help log code outputs that can facilitate the debugging process.
• Static Code Analyzers: A static code analyzer inspects your code for any potential bugs or issues without actually running it. It can help you flag potential bugs before they’re released in production. It’s a commonly used technique in white box testing to identify errors in static code.

Benefits of debugging

Debugging has numerous benefits, such as:

• Improved software reliability: It ensures your software functions and performs more reliably for your users.
• Enhanced performance: Bugs and unwanted issues may hamper your application’s performance. Debugging allows you to eliminate these bugs and, in turn, improve the performance of your application.
• Improved user experience: The end-user impact of debugging is creating a more user-friendly software usage experience that leaves a good impression on your customers.
• Improved costs: Debugging crucial bugs that can lead to downtime or complete software crashes can save costs for your company and avoid a negative impact on your business.

Challenges of debugging

Debugging by itself poses certain challenges that can be difficult to navigate even if you use the most effective debugging technique. With the increasing complexity of modern software, debugging may become more complex too. Standard debugging techniques may not prove to be effective, so you should always try to evolve these techniques as your software evolves in complexity.

It’s also important to note that debugging by itself can be a monotonous and time-consuming process. It can drain the mental bandwidth of your engineering teams. Sometimes, seeking a fresh perspective from a teammate or tackling debugging sessions with a relaxed and well-rested mind can help overcome this challenge.

What strategies can I use to reduce the occurrence of bugs in my software?

“Everyone knows that debugging is twice as hard as writing a program in the first place. So if you’re as clever as you can be when you write it, how will you ever debug it?”
– Brian Kernighan, renowned computer scientist and author of The Elements of Programming Style

By following the given strategies, you can reduce the occurrence of bugs in your software to simplify and, in some cases, even eliminate your debugging sessions.

• Write clear and maintainable code that’s easy to understand and work on top of.
• Follow thorough code reviews to ensure code quality amongst your team.
• Implement rigorous testing, both manual and automated, to catch bugs before they’re released.

Conclusion

Debugging is a crucial part of software development. Using the right debugging technique coupled with the right set of tools, you can improve your customer satisfaction and your business outcomes, in addition to the numerous other benefits that debugging offers.

This post was written by Siddhant Varma. Siddhant is a full stack JavaScript developer with expertise in frontend engineering. He’s worked with scaling multiple startups in India and has experience building products in the Ed-Tech and healthcare industries. Siddhant has a passion for teaching and a knack for writing. He’s also taught programming to many graduates, helping them become better future developers.