Mining Energy-Aware Commits

Over the last years, energy consumption has become a first-class citizen in software development practice. While energy-efficient solutions on lower-level layers of the software stack are well-established, there is convincing evidence that even better results can be achieved by encouraging practitioners to participate in the process. For instance, previous work has shown that using a newer version of a concurrent data structure can yield a 2.19x energy savings when compared to the old associative implementation [75]. Nonetheless, little is known about how much software engineers are employing energy-efficient solutions in their applications and what solutions they employ for improving energy-efficiency. In this paper we present a qualitative study of "energy-aware commits". Using Github as our primary data source, we perform a thorough analysis on an initial sample of 2,189 commits and carefully curate a set of 371 energy-aware commits spread over 317 real-world non-trivial applications. Our study reveals that software developers heavily rely on low-level energy management approaches, such as frequency scaling and multiple levels of idleness. Also, our findings suggest that ill-chosen energy saving techniques can impact the correctness of an application. Yet, we found what we call "energy-aware interfaces", which are means for clients (e.g., Developers or end-users) to save energy in their applications just by using a function, abstracting away the low-level implementation details.