Thursday, May 7, 2009

Technical Debt is like a steep hill, not a brick wall

[This was originally posted at]

Overtime, bad software decisions (design, coding, process) get compounded, like interest on a loan, and effectively presents the team with a "technical debt" that yearns to be repaid. This debt weighs down the system, making it harder and harder to make changes or add new features. One way to measure technical debt is by lines of code that require maintenance. Therefore you can reduce debt by reducing lines of code (codeGen, refactor, automate, buy instead of build, etc...).

For example, a developer may copy and paste duplicate code a hundred times (like in HTML or SQL), or create thousands of lines of tedious plumbing code, or create an army of brittle JavaScript files, or write an entire app with no code coverage. Many of the best practices out there are designed to explicitly reduce technical debt.

One thing to note is that technical debt is like a steep hill that can go infinitely high. You can go fast bicycling on a flat road, but as that road turns into a steep hill that gets gradually steeper, you slow down. In software terms, because code may have been copied to 10 different places, making a single change requires 10 separate updates - so it takes longer.

I don't think technical debt is like a brick wall - where suddenly at a specific point you're blocked and you simply cannot go further. And that's part of the problem. As long as you're moving, albeit slower and slower, it's seductive to think that you can still keep making "enough" progress so you don't need to change yet. The stubborn leader can just keep pushing on: "longer hours, more developers..." There are two choices to make: keep going forward, or turn around. However, if you were to hit that brick wall, then it forces you to stop and reevaluate. It's easier in the sense that you now only have one choice - you must "turn around".

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