Tales from the Code #1: The Effective Impact of Code Refactorings on Software Energy Consumption

Abstract

Software maintenance and evolution enclose a broad set of actions that aim to improve both functional and non-functional concerns of a software system. Among the non-functional concerns, energy consumption is getting more and more traction in the industry, no matter the software is mobile or deployed in the cloud. In this context, the impact of code refactorings on energy consumption remains unclear, though. In particular, while the state of the art investigated the impact of some specific code refactorings on dedicated benchmarks, we miss an assessment that those apply to more comprehensive and complex software. To address this threat, this paper studies the evolution of the energy consumption of 7 open-source software developed for more than 5 years. Then, by focusing on the impact on energy consumption of changes involving code refactorings, we intend to assess the effects induced by such code refactorings in practice. For all these software systems we studied, our empirical results report that the code refactorings we mined do not substantially impact energy consumption. Interestingly, these results highlight that i) structural code refactorings bring energy-preserving changes to the code, and ii) major energy variations seem to be related to functional and computational code evolutions.