Investigating the Correlation between Performance Scores and Energy Consumption of Mobile Web Apps

Context. Developers have access to tools like Google Lighthouse to assess the performance of web apps and to guide the adoption of development best practices. However, when it comes to energy consumption of mobile web apps, these tools seem to be lacking. Goal. This study investigates on the correlation between the performance scores produced by Lighthouse and the energy consumption of mobile web apps. Method. We design and conduct an empirical experiment where 21 real mobile web apps are (i) analyzed via the Lighthouse performance analysis tool and (ii) measured on an Android device running a software-based energy profiler. Then, we statistically assess how energy consumption correlates with the obtained performance scores and carry out an effect size estimation. Results. We discover a statistically significant negative correlation between performance scores and the energy consumption of mobile web apps (with medium to large effect sizes), implying that an increase of the performance score tend to lead to a decrease of energy consumption. Conclusions. We recommend developers to strive to improve the performance level of their mobile web apps, as this can also have a positive impact on their energy consumption on Android devices

A practical type system for safe aliasing

Aliasing is a vital concept of programming, but it comes with a plethora of challenging issues, such as the problems related to race safety. This has motivated years of research, and promising solutions such as ownership or linear types have found their way into modern programming languages. Unfortunately, most current approaches are restrictive. In particular, they often enforce a single-writer constraint, which prohibits the creation of mutable self-referential structures. While this constraint is often indispensable in the context of preemptive multithreading, it can be worked around in the case of single threaded programs. With the recent resurgence of cooperative multitasking, where processes voluntarily share control over a single execution thread, this appears to be interesting trade-off. In this paper, we propose a type system that relaxes the usual single-writer constraint for single threaded programs, without sacrificing race safety properties. We present it in the form of a simple reference-based language, for which we provide a formal semantics, as well as an interpreter