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AI makes tech debt more expensive

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466 points 0x63_Problems | 1 comments | 14 Nov 24 16:01 UTC | HN request time: 0.215s | source
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dkdbejwi383 ◴[14 Nov 24 16:51 UTC] No.42138113[source]▶
> However, in ‘high-debt’ environments with subtle control flow, long-range dependencies, and unexpected patterns, they struggle to generate a useful response

I'd argue that a lot of this is not "tech debt" but just signs of maturity in a codebase. Real world business requirements don't often map cleanly onto any given pattern. Over time codebases develop these "scars", little patches of weirdness. It's often tempting for the younger, less experienced engineer to declare this as tech debt or cruft or whatever, and that a full re-write is needed. Only to re-learn the lessons those scars taught in the first place.

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hn_throwaway_99 ◴[15 Nov 24 00:18 UTC] No.42142736[source]▶
There is a pretty well known essay by Joel Spolsky (which is now 24 years old!) titled "Things You Should Never Do" where he talks about the error of doing a rewrite: https://www.joelonsoftware.com/2000/04/06/things-you-should-... . While I don't necessarily agree with all of his positions here, and given the way most software is architected and deployed these days some of this advice is just obsolete (e.g. relatively little software is complete, client-side binaries where his advice is more relevant), I think he makes some fantastic points. This part is particularly aligned with what you are saying:

> Back to that two page function. Yes, I know, it’s just a simple function to display a window, but it has grown little hairs and stuff on it and nobody knows why. Well, I’ll tell you why: those are bug fixes. One of them fixes that bug that Nancy had when she tried to install the thing on a computer that didn’t have Internet Explorer. Another one fixes that bug that occurs in low memory conditions. Another one fixes that bug that occurred when the file is on a floppy disk and the user yanks out the disk in the middle. That LoadLibrary call is ugly but it makes the code work on old versions of Windows 95.

> Each of these bugs took weeks of real-world usage before they were found. The programmer might have spent a couple of days reproducing the bug in the lab and fixing it. If it’s like a lot of bugs, the fix might be one line of code, or it might even be a couple of characters, but a lot of work and time went into those two characters.

> When you throw away code and start from scratch, you are throwing away all that knowledge. All those collected bug fixes. Years of programming work.

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1. nosianu ◴[15 Nov 24 10:58 UTC] No.42145747[source]▶
> *"Things You Should Never Do" where he talks about the error of doing a rewrite

As a funny aside, I actually noticed this in a completely different field, serial stories on the web (mostly on RoyalRoad)!

Occasionally an author will attempt a rewrite of a story either because the feedback was very critical, or they did not like where their own story had ended up.

I have yet to see a single example for a truly successful rewrite, where the rewrite was really significantly (or at all) better than the original. Usually the rewrite will not get any better ratings or more readers than the first draft - and for good reasons.

There will be improvements, but it will be on the edges. At the core it still remains the same story with the same problems, and some style changes or some improved dialogs don't change that.

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By the way, there is an old 2016 HN thread with 106 comments "When to Rewrite from Scratch – Autopsy of Failed Software" -- https://news.ycombinator.com/item?id=11553813

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A rewrite story I heard a long time ago and that I think would actually work best when the issues are severe was from a company that lost all their code (I don't remember the context, it was not data loss). They had spent many years to get to where they had been when they lost everything. They thought it would take almost as many years to get there again, but they started anyway. Turned out they were done in only half a year this time, and much better!

I think having to work with and around your old code (or story, in the RoyalRoad example) is a severe limit on how much you can improve. Your thoughts are not free, most of your mental effort will be around reusing the old code.

That is my own experience too: Writing the software is not my bottleneck. It's finding out what to write in the first place, and the many many small agonizing decisions along the way. I now see that meta knowledge is far more important. For very large projects it may be more difficult though.

I did this myself once, in the early Internet growth days. The company had its own equivalent of PHP (which was still pretty new at the time) and a business software based on it. I was tasked with refactoring the 1.0 version. I threw the code away after a brief look and rewrote from scratch. I did it because I believed having to consider the existing code would be much slower than writing new.

I have no complaints about the 1.0 version, the first version is always limited by the by then still low comprehension of the problem. I think version 2.0 releases might benefit the most from just throwing the 1.x code away and starting fresh, if the understanding of the problem evolv3ed substantially during - and through - the development.