Software Aging (1994) [pdf]

> Programs, like people, get old. We can't prevent aging, but we can understand its causes, take steps to limit its effects, temporarily reverse some of the damage it has caused, and prepare for the day when the software is no longer viable.

> A sign that the Software Engineering profession has matured will be that we lose our preoccupation with the first release and focus on the long term health of our products. Researchers and practitioners must change their perception of the problems of software development. Only then will Software Engineering deserve to be called Engineering.

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According to the article, there are two types of software aging: change or lack thereof.

- Lack of movement: failure of the product's owners to modify it to meet changing needs

- Ignorant surgery: result of the changes that are made

In addition, distinctly from aging, there's accumulation: "the system slow down caused by failure to release allocated memory" or storage, file system filling up, etc.

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Some of the costs of aging:

- Inability to keep up

- Reduced performance

- Decreasing reliability

Strategies to reduce such costs:

- Design for change

- Documentation

- Reviews

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How to deal with aged software:

- Retroactive documentation

- Incremental modularization

- "Amputation"

- "Major surgery" - Restructuring

There is also a considerable body of work on so called Software Rejuvenation, to mitigate software aging phenomena, lead by Prof Kishor Trivedi, from Duke U