Coding Bugs and Expensive Lessons in Technical Debt



Coding Bugs and Expensive Lessons in Technical Debt


The Unexpected Massive Discount

Meet Sarah, an e-commerce entrepreneur who prides herself on offering competitive pricing. One day, a loyal customer emails her, thanking her for an "amazing surprise discount" on their order. Puzzled, Sarah reviews the pricing logs and discovers that her system applied a 50% discount to several items in the customer's cart—unintentionally.


The root cause? A logical bug buried deep in her pricing algorithm. During a recent feature update, a developer inadvertently introduced a condition that applied the maximum discount to any cart containing more than five items, instead of only for specific promotional categories. The bug didn’t crash the system, and most customers didn’t notice the discrepancy. However, once Sarah realized the mistake, she had to scramble to fix the issue, refund overcharges to non-affected customers (to retain trust), and audit months of past transactions.


This seemingly harmless oversight became an expensive lesson in technical debt. Sarah vowed never to skip detailed testing or code reviews again.


The Definition of Technical Debt

Technical debt is the accumulation of hidden costs in a system or codebase caused by shortcuts, compromises, or deferred maintenance, which eventually lead to greater complexity, errors, and effort to resolve.


The Leaky Server: A Memory Leak Nightmare

On the other side of the tech spectrum, let’s meet Alex, a backend engineer managing a high-traffic IoT platform. The platform processes millions of sensor updates daily, feeding data into analytics dashboards for clients. Everything seems fine until, after a few weeks, Alex starts receiving complaints about sluggish dashboard performance.


Investigating the issue, Alex notices that the server’s memory usage keeps climbing steadily over time. Restarting the service temporarily fixes the problem, but the trend continues. Using a tool like Valgrind, Alex discovers the culprit: a memory leak in a function that processes incoming sensor data. A small block of memory allocated for every sensor update wasn’t being freed after use.


The memory leak, while tiny for each individual event, compounded into a massive resource drain. Fixing it required not only identifying the leak but also restructuring parts of the code to prevent future occurrences. In hindsight, Alex realized this was technical debt accrued from rushing to deploy a new feature without fully reviewing the memory management code.


The Takeaway: Avoiding These Scenarios

These imagined scenarios illustrate how logical bugs and memory leaks can turn into costly technical debt. Sarah’s pricing error disrupted customer trust and sales records, while Alex’s memory leak degraded system performance, risking client dissatisfaction. Both could have been mitigated with preventative measures, like better testing, code reviews, and static analysis tools.


Conclusion

For developers, the lesson is clear: every shortcut taken to "save time" during coding can lead to a long-term liability. By investing in thorough testing, maintaining clear documentation, and prioritizing maintainability, you can minimize the risk of logical bugs, memory leaks, and other forms of technical debt.



Image: Gundula Vogel from Pixabay

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