A few years ago, I assumed that if my tests passed and everything worked in staging, I didn’t have much to worry about.
Then I started working on applications with real traffic.
That’s when I realized some bugs have nothing to do with incorrect business logic. They’re caused by two perfectly valid requests trying to update the same data at the same time. The result can be anything from overwritten data to deadlocks that only appear under load, making them frustrating to reproduce and debug.
What surprised me most is that the fix often isn’t rewriting your application code. It’s understanding how your database handles concurrency and knowing when transactions or row-level locking are the right tools for the job.
I came across this article while reading about Django concurrency. It does a good job of explaining race conditions and deadlocks with practical examples instead of only covering the theory.
<a href="https://www.kubeblogs.com/avoid-race-conditions-and-deadlocks-in-django-step-by-step-guide/" target="_blank" rel="noopener nofollow">https://www.kubeblogs.com/avoid-race-conditions-and-deadlocks-in-django-step-by-step-guide/</a>

Divyansh

Race conditions and deadlocks in web applications often have nothing to do with incorrect business logic — they emerge when two valid requests try to update the same data simultaneously. The fix usually lies in understanding how your database handles concurrency and knowing when to use transactions or row-level locking. A linked Django-focused guide covers these issues with practical examples rather than pure theory.

The Bug Wasn't in Our Code. It Was Two Requests Hitting It at the Same Time.

These are very difficult to find and debug… Also what doesn’t help is the flakiness of such issues.