Mining energy – aware commits: exploring changes performed by open – source developers to impact the energy consumption of software systems

• Main Author: MOURA, Irineu Martins de Lima
• Publication Date: 2015
• Format: Master thesis
• Language: eng
• Source: Repositório Institucional da UFPE
• Download full: https://repositorio.ufpe.br/handle/123456789/17809
• topic: Mineração de Repositório de Software. Consumo de Energia. GitHub; Software Repository Mining. Energy-Aware. GitHub

Energy consumption has been gaining traction as yet another major concern that mainstream software developers must be aware of. It used to be mainly the focus of hardware designers and low level software developers, e.g., device driver developers. Nowadays, however, mostly due to the ubiquity of battery-powered devices, any developer in the software stack must be prepared to deal with this concern. Thus, to be able to properly assist them and to provide guidance in future research it is crucial to understand how they have been handling this matter. This thesis aims to aid in this regard by exploring a set of software changes, i.e., commits, to obtain insights into actual solutions implemented by open source developers when dealing with energy consumption. We use as our main data source GITHUB, a source code hosting platform for collaborative development, and extract a sample of the available commits across several different projects. From this sample, we manually curate a set of energy-aware commits, that is, any commit that refers to a source code change where developers intentionally modify, or aim to modify, the energy consumption (or power dissipation) of a system or make it easier for other developers or end users to do so. We then apply a qualitative research method to extract recurring patterns of information and to group the commits that intend to save energy into categories. A small survey was also conducted to assess the quality of our analysis and to further expand our understanding of the changes. During our analysis we also cover different aspects of the commits. We observe that the majority of the changes (~47%) still target lower levels of the software stack, i.e., kernels, drivers and OS-related services, while application level changes encompass ~34% of them. We notice that developers may not always be certain of the energy consumption impact of their changes before actually performing them, among our dataset we identify several instances (~12%) of commits where developers show signs of uncertainty towards their change’s effectiveness. We also highlight the possible software quality attributes that may be favored over energy efficiency. Notably, we spot a few instances of commits where developers performed a change that would negatively impact the energy consumption of the system in order to fix a bug. It is also worth noting, we draw attention to a specific group of changes which we call "energy-aware interfaces". They add tuning knobs that can be used by developers or end users to control the energy consumption of an underlying component.