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Why Does Software Rot?

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Re: Why Does Software Rot?

#21

Post by beat »

carsongross wrote: post #7
nbouscal wrote: post #4

Earlier quoted context omitted.

It rots in the sense that it becomes harder to change (or fix) over time, even if the code stays the same. This happens via loss of institutional knowledge as people forget how it works, loss of knowledge of the technologies used as they're replaced, etc. It's not just the complexity. Old code is usually harder to change than new code, even if they're equally complex.

That isn't rot. The metaphor doesn't make any sense. Software literally does not change. Except for the occasional cosmic ray, I can think of few things less appropriate to apply the term "rot" to.

It's a metaphor, not an equivalence. It doesn't even have to be in the same field, as long as the meaning is conveyed. Bit rot is an excellent metaphor, even though it's nothing like physical rot if you get pedantic about it.

Re: Why Does Software Rot?

#22

Post by nbouscal »

carsongross wrote: post #7
nbouscal wrote: post #4

Earlier quoted context omitted.

It rots in the sense that it becomes harder to change (or fix) over time, even if the code stays the same. This happens via loss of institutional knowledge as people forget how it works, loss of knowledge of the technologies used as they're replaced, etc. It's not just the complexity. Old code is usually harder to change than new code, even if they're equally complex.

That isn't rot. The metaphor doesn't make any sense. Software literally does not change. Except for the occasional cosmic ray, I can think of few things less appropriate to apply the term "rot" to.

You're the first person I've heard say that the metaphor doesn't make any sense; meanwhile, a lot of people regularly use it, which implies that it makes sense to them. You're welcome to not like the metaphor, but you don't really get to declare that it's objectively wrong… it's a metaphor.

Re: Why Does Software Rot?

#23

Post by ArkyBeagle »

jussaskin wrote: post #20
ArkyBeagle wrote: post #15

Earlier quoted context omitted.

Through the miracle of virtual machines, this is much less so. VMs are the NAT of computer systems.

Even though the VM image and tooling may still be runnable, the world around it with which it must interact continues to evolve and can leave your software obsolete.

One for one thing, another for another.

Re: Why Does Software Rot?

#25

Post by Asooka »

ArkyBeagle wrote: post #14
boznz wrote: post #10

Unless your sandboxed in a self contained hardware and software environment (such as an embedded system) you will eventually be screwed. (rot sounds like a gradual degradation its generally not in my position) Standards changes and OS Updates are the biggest culprit; The Vista update broke a couple of my old programs (written for Windows 95) due to the user access control changes, another was broke due to the fact it…

This is because there's little glory in simply making things work. There is glory in making things that look shiny and new. As they say, "Absolutem Obsoletum". And congratulations on understanding exactly why I prefer embedded systems - you don't have to keep chasing the dragon of the fashionable new thing ( which is invariably old wine in new skins ). It is not that there is no new wine it is just that proportionall…

In a way, isn't this a form of make-work for software engineers? Plus, I'm not sure what is worse - having to remake things every 5 years or so slightly differently, or not having jobs.

Re: Why Does Software Rot?

#26

Post by akkartik »

lifeisstillgood wrote: post #6

Three reasons: 1. The code is the same but the people using it forget / never knew the reasons it was built that way - and so it looks rotten for the job 2. Because requirements change and people try to make the old code do new things without cleaning up / refactoring correctly - so it now does neither job well, and looks rotten. 3. Because the environment / platform changes, the FTP server is moved to a new data cen…

Your reasons are very similar to mine: http://akkartik.name/about.

A. Backwards compatibility considerations.

B. Churn in personnel.

C. Vestigial features.

Awesome! Comparing the two, I merged your 2 and 3 into a single reason, considering both as cases of environmental change. In its place I have a new one: changing personnel causing evaporation in system knowledge. Did you consider this? Now I think about it, maybe it overlaps with your 1 (my C).

So the final mapping is perhaps:

1 B, C

2, 3 A

Re: Why Does Software Rot?

#27

Post by jussaskin »

I find that integrated tests in software projects go a long way to reducing rot. When something eventually invariably breaks due to some external factor, the test suite greatly reduces the time to identify and fix the problem.

Re: Why Does Software Rot?

#28

Post by akkartik »

carsongross wrote: post #3

What does rot even mean, in terms of software? As far as I can tell, he means "Why is complex software hard to change " which is a reasonable, though fairly easy to answer, question. Software doesn't rot. New features or refactors screw it up. New needs or technologies may make it obsolete. But it doesn't rot, and people who talk that way are often busy-body rewriters who want to pitch the existing implementations, w…

I think you're taking the phrasing too literally. When we say software rots, we're not just talking about the bits that make up a program, but also its interface with its environment, and the knowledge about it in people's brains. Both those connections are indeed subject to drift/evaporation/entropy. The two failure modes you mentioned are symptoms of that underlying evaporation.

I spend a lot of time thinking about this (http://akkartik.name/about), but lately I try to steer clear of metaphors, because they're so often clear in my mind but utterly opaque to someone else's. So, I don't care what we call it, as long as more people try to fix the problem.

Re: Why Does Software Rot?

#29

Post by jussaskin »

ArkyBeagle wrote: post #23
jussaskin wrote: post #20

Earlier quoted context omitted.

Even though the VM image and tooling may still be runnable, the world around it with which it must interact continues to evolve and can leave your software obsolete.

One for one thing, another for another.

Fair enough.

Re: Why Does Software Rot?

#30

Post by bostik »

beat wrote: post #18
jussaskin wrote: post #9

Software rots if you can no longer set up the exact tool chain and environment (compiler, build tool, OS version, external database, etc) required to build and run it. Even interpreted languages suffer from this problem as features are subtlely changed - by design or accident. It doesn't matter if your project is using an ancient version of VC++ or a two year old version of NodeJS. If it doesn't keep up with the late…

Some smart dude, don't remember who, said that every single line of code becomes technical debt the moment it is written.

Legacy software is the code you wrote before lunch.[0]

0: http://www.russmiles.com/essais/dont-think-legacy-software-t...

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