Investigating the effect of design patterns on energy consumption

Gang of Four (GoF) patterns are well-known best practices for the design of object-oriented systems. In this paper, we aim at empirically assessing their relationship to energy consumption, ie, a performance indicator that has recently attracted the attention of both researchers and practitioners. To achieve this goal, we investigate pattern-participating methods (ie, those that play a role within the pattern) and compare their energy consumption to the consumption of functionally equivalent alternative (nonpattern) solutions. We obtained the alternative solution by refactoring the pattern instances using well-known transformations (eg, replace polymorphism with conditional statements). The comparison is performed on 169 methods of 2 GoF patterns (namely, State/Strategy and Template Method), retrieved from 2 well-known open source projects. The results suggest that for the majority of cases the alternative design excels in terms of energy consumption. However, in some cases (eg, when the method is large in size or invokes many methods) the pattern solution presents similar or lower energy consumption. The outcome of our study can be useful to both researchers and practitioners, because we: (1) provide evidence on a possible negative effect of GoF patterns, and (2) can provide guidance on which cases the use of the pattern is not hurting energy consumption.