Tech Debt is Silly
A lot of developers bandy about the metaphor of technical debt like it's a real thing. This in turn
leads to some serious problems in communication. Never forget that
tech debt is a metaphor.
Its goal is to provide some sort of analogy for a thing someone else doesn't understand. If you
cargo cult a metaphor and keep repeating it all the time, the metaphor replaces the real thing in
the audience's head.
Physicists deal with this all the time when dealing with invisible forces. Electricity is water in a pipe. Uncertainty is a cat in a box. Electrons spin like little billiard balls (and have up and down spins, funny that). These and many like them are just metaphors for real mathematical equations describing observed phenomena. But metaphors get treated like ground truth in people's heads if they never really learn what lies behind them. Spoiler alert, your non-technical colleagues will likely never understand software development like you do. So repeating a metaphor is going to make your life harder than it already is. Especially if you choose a poor metaphor.
Comparing Real Debt to Tech Debt
Why is it a bad metaphor? What makes a good metaphor? A metaphor allows someone to link a new concept to existing understanding by leveraging what they already understand to make assumptions about this unfamiliar concept. Notice how that is a double edged deal. If someone's got a lay understanding, this may work, but it often breaks down fast if the person really understands the other concept.
A good metaphor then would be one that goes far on that understanding before breaking down. Tech
debt does not. Tech debt almost immediately doesn't work the same as real debt. It only barely holds
if your understanding of debt is that,
debt is bad, and that you can sometimes say we don't
have time and move on with the assumption that you'll,
pay it back later. So, let's examine
how debt works and how tech debt just doesn't. Here's a couple totally normal debt related things
that just don't map.
What's The ROI For Tech Debt?
When a non-technical person thinks about debt, that immediately means it has a value. Sure a value with amortized cost, but it implies that I can sign on for a bunch of this debt and just have the company pay it back in the future. Yeah, business thinking people do really consider debt this way. Debt is a way to race against return on investment and accelerate profits. The problem is these people are not accountants. It's the bean counters job to track whether or not we can actually repay these obligations. Debt is free money subject to accounting review.
This immediately runs into problems with tech debt. What's the value of this debt? I don't have a metric to give it a debt to dollars conversion, do you? What even is a tech debt unit? How do we quantify it? If we're going to use the language of finance to talk about developing software you better believe there needs to be hard numbers involved.
How's The Interest Rate?
Similarly, what's the interest rate on this debt? We haven't quantified what a debt unit is, how can we calculate the cost of the time sink it's becoming and track it over time? Does this cost increase? Is it linear, exponential, or constant? How does interest fluctuate? How does interest impact yield? Interest rates are a core concept to debt but make no sense at all to technical debt. There's no obvious comparison. Well, there is one…
Don't even mention bit rot. Is that different than tech debt? How is rotting related to debt? They're completely different balance sheet items. How do digital items decay anyway? I thought only analogue goods could. See, this simplifies nothing and is really a stretch. It's also got a completely different name. I mean, bit rot's also a bad metaphor, but that's not this article.
Notice how a bad metaphor not only links incorrect assumptions to the concept, but also makes it harder to link related concepts to the poor metaphor.
We're Either Solvent or Bankrupt
Another problem with tech debt is that it implies solvency. There are higher and lower debt loads, but as long as you keep meeting payments, you're fine. It eats into profits, but the accountants already did the math. The debt is fine because we're likely going to make more with it than without it. Even with a lower than projected revenue we'll have no problem paying these obligations.
Developers aren't making these same calculated trade-offs. We still don't have a unit for this imaginary debt. Who's tracking if we're about to bankrupt the company by failing to meet contractual obligations or by delivering insecure software leading to litigation? How can you express the debt load? It's high because I feel like it's high? If an accountant tried that they'd be laughed out of the room. If we chose financial language to describe a complexity problem, don't be surprised when financial analysis is what people reach for to understand the problem.
Quick, name drop a refactor like anyone understands that and walk away.
So you've let it snowball into full blown ball of mud and the company's technologically bust. What do you do? Well assuming the company isn't actually bankrupt because of your poor decisions, it's laying off many of those responsible and starting a rewrite. Yeah, rewrites turn out to be something you can sort of indefinitely put off. Sure it takes days to do even basic things and we're now losing a developer every other week, but that's not my problem as a non-developer. What on earth is institutional knowledge? You'd better be documenting things down there in product development!
See, you're flying blind. You have no idea if you're about to bankrupt the company for failure to meet contractual obligations. You've no idea if a competitor is about to launch a killer design that you simply cannot pivot in time to counteroffer. There's no risk profile that a dev is about to add an authentication bypass to your product because there's 4 different legacy authentication APIs and they'll pick the wrong one for the job.
If you cannot measure it, you cannot manage it.
The Job Shop and Cleanliness
So debt barely works. What are we really trying to capture? It's the need to periodically rewrite small chunks of the software to take advantage of what you've learned about it and what it'll need to most likely do going forward. It's replacing 40 copy pasted chunks of code with a single function. It's going back to fix that time you raced the clock hacking together the demo for Monday morning last week. It's upgrading parts to take advantage of the state of the art to prevent people tripping over the unexpectedly inconsistent behaviour.
After thinking about this for a while, I think a much better metaphor is working in a job shop. A job shop is the department (on site or outsourced) in a physical engineering focused organization where one-off or at least uncommon components are made. It's a highly flexible environment where needs are met mostly on demand. There's a lot of machinery that often sits idle but each is vital to executing certain types of tasks. If not managed correctly, the complexity of changing requests and the shop itself can begin to conflict leading to inefficacy. You have to take care to fix broken machines, but in proportion to utilization. There's trade-offs to the entire process, and all the time you have to take workplace safety seriously.
I think this better captures both how developers see themselves and how non-developers see the code
monkeys. For developers, it reflects the dynamic nature of the job. The
outsiders don't really see (machinery and workflows) and reflects better why it's important to take
cleanliness seriously. The metaphor is the messy job shop. When you don't take time to clean up, bad
Sure, you can go fast by just leaving the scraps where they land, leaving your tools everywhere between jobs, and just doing the minimum to get the prototype ready. Someone will end up with a workplace injury as a result. Sure code usually doesn't maim people (robotics, defence, and some embedded devs obviously aside), but there are definitely statistically likely consequences to letting a code base's complexity spiral out of control.
For example, you don't have to take the time to remove the old authentication flows after the new one's in place (it's a lot of work to clean up after all), but some dev will trip on it and we'll have to deploy the public relations team to cover for us when all our customer's data hits the web. Security degrades when developers don't fully understand what the code they're writing can do when an attacker attempts to abuse it.
Another more mundane mess, it takes a dozen files over three code bases to add that button because you have to climb over half a dozen legacy decisions that left tools in all the wrong places. All that moving about takes time. It makes parts far more complicated and the work take much longer. Then the workflow dictates you get others to also crawl over all that to review the changes before we ship. If we just took time to clean up the mess, now and in the future you only need one (or maybe two) changes to do something this simple. Remove what you no longer need to be laying around (prevent trips and spills). Likewise, keep machines often used together, physically near (reduce the time spent moving between parts of the code).
Most people can only stand working in a mess for so long. People who take pride in an orderly environment will leave if things get too insane. Finding a zip tie holding the breaker closed after someone used a jigsaw to cut an I-beam because the belt saw's been broken for the last month and you're going to debate quitting to work elsewhere. Same thing if you constantly get pressured into shipping too fast, cutting corners, and making only half understood changes to the product.
When people leave, they take domain expertise with them. Even if you can teach a new hire this complex mess, it's much harder when you have to stop and explain why we keep the saws behind the ceiling tiles. You see, it's because at one point the product… And we had to… Which meant… Obviously! Hope you're as excited to work here as we are to have the help. No, we don't have time to clean up the saws, now help me cut the trigger guard off this angle grinder so we can ship by end of day.
There Is Such a Thing As Too Clean
Unlike debt (where no debt is reasonable), it's not reasonable to keep the workshop a class 10,000 cleanroom capable of aerospace manufacturing unless that's what you're really doing all day. Some systems require an extreme amount of cleanliness (human safety systems, security critical systems, payment processing, compilers, libraries, etc.) but every single one still requires care and attention. Clean up the broken glass, install safety bumpers on sharp edges, put out the spill sign to document the big stuff for now, secure the flammables, and sweep the floors every so often.
Will our customers notice? Well, if you don't have time to get it right because you're actively ignoring the mess, maybe? Other teams at other companies who keep a clean shop can just turn around faster. You've also potentially got a talent problem. Turnover is expensive. If other shops are tidier, where you can place your hand on a hammer when you need one, why would you keep putting up with this nonsense? Mission sure, but your experience is dictated by the worst part. If that's hours a day wrestling with your build systems, nobody's happy. Fix it! Passion is always noticeable in the results.
That's why I think a job shop's cleanliness is a much more apt metaphor than debt. Cleanliness is not a business trade-off, it's a human trade-off. You trade-off safety and sanity for speed. Cleaning up a mess that's grown out of control is much more work than cleaning as you go. There are limits to clean, but they're best defined by those who work in it through standards and negotiation. If we don't get it right, regulation will likely step in to cover cases where our mess is hurting people by imposing bureaucratic checkboxes. That won't improve morale, but will reduce direct harms. Yay, TPS reports and DFMEA meetings.