Thursday 29 April 2010

Technical Debt Credit Rating

A while back I wrote about how closely technical debt paralleled financial debt and then a short follow-up post with the meta-message that, through the right reductionism, certain things will always cost you an inescapable minimum and the decision that you really have is about where you choose to make that payment (I argued that you either pay through the correct design and build initially, or you pay through unnecessarily increased maintenance costs later).

Outlawing technical debt is as foolhardy as always cutting corners - sometimes the right thing to do is to take a hit to get something out sooner or in a certain shape - the problem is in the repayments; in other words, they often don't exist. And if you don't go back and sort your hacks out early they tend to accumulate in the system and before you know it developing on it is like moving through treacle (and the treacle occasionally catches fire). Everything else you do takes that much longer and is that much more expensive (and those are business metrics) and can have unintended consequences - it's a crippling burden just like its financial counterpart.

I have a rule - no one is allowed to take technical shortcuts through a project [where that = incur some technical debt] without showing where, in the same plan, they go back to do some refactoring so that our long-term assets remain sustainable. We're pretty lucky at Sporting Index; most of our stakeholders value technology and recognize how critical it is to the business, so it's a conversation I rarely have to have - but I know many other companies are less fortunate.

So now I think I have a better idea. It came to me while I was thinking about why, if technical debt is so similar to real debt, it doesn't regulate itself in the same way - and I think that's becuase there is no concept of creditworthiness in technical debt, in other words no assessment of a team's ability to 'repay' a quality compromise (read: loan of functionality to the business ahead of when it otherwise would have been ready) alongside all the other outstanding quality compromises that they already have.

But we might be able to simulate that...

Imagine giving each product manager a 'credit rating' of, say, 3 - meaning they could call for unsustainable technical shortcuts 3 times as they worked with the delivery team to determine their solutions. Once those 3 debt points were used, that product manager would be unable to encourage the team to make further quality compromises until at least one of those was paid back. If you have product managers with a demonstrated track record of revisiting earlier deliveries to address technical debt then why not give them 5? A higher creditworthiness ought to enable an individual to take on more concurrent debt as we can be more confident that they'll come back to service it.

I pretty much guranttee that any product manager's cavalier attitude towards shortcuts would change and they'd suddenly treat technical debt as the instrument it really is and use it only where it mattered materially. That, ladies and gentlemen, is a feedback loop.

The downside is that you'd have to be better at tracking this sort of thing and, like any other method, it'll need some discipline when a product manager with maxed out technical debt points wants just one more shortcut. If you've ever had to maintain a spaghetti codebase (as most of us have at some point) then you'll know that these things need closely policed anyway, so perhaps being forced into formally tracking it isn't so bad.

1 comment:

Jan said...

I like the idea! I think it would work in larger companies with a number of program managers.

We have a rule, that every 6th release (we release monthly) is a pure-no-features-refactoring release. If you stick to a rule like this, you tend not to accumulate too much technical debt.