Energy consumption in Java: An early experience

There has been a 10,000-fold increase in performance of supercomputers since 1992 but only 300-fold improvement in performance per watt. Dynamic adaptation of hardware techniques such as fine-grain clock gating, power gating and dynamic voltage/frequency scaling, are used for many years to improve the computer's energy efficiency. However, recent demands of exascale computation, as well as the increasing carbon footprint, require new breakthrough to make ICT systems more energy efficient. Energy efficient software has not been well studied in the last decade. In this paper, we take an early step to investigate the energy efficiency of Java which is one of the most common languages used in ICT systems. We evaluate energy consumption of data types, operators, control statements, exception, and object in Java at a granular level. Intel Running Average Power Limit (RAPL) technology is applied to measure the relative power consumption of small code snippets. Several observations are found, and these results will help in standardizing the energy consumption traits of Java which can be leveraged by software developers to generate energy efficient code in future.