Characterization of Unnecessary Computations in Web Applications

Abstract

Web applications are widely used in many different daily activities-such as online shopping, navigation through maps, and social networking-in both desktop and mobile environments. Advances in technology, such as network connection, hardware platforms, and software design techniques, have empowered Web developers to design Web pages that are highly rich in content and engage users through an interactive experience. However, the performance of Web applications is not ideal today, and many users experience poor quality of service, including long page load times and irregular animations. One of the contributing factors to low performance is the very design of Web applications, particularly Web browsers. In this work, we argue that there are unnecessary computations in today's Web applications, which are completely or most likely wasted. We first describe the potential unnecessary computations at a high level, and then design a profiler based on dynamic backward program slicing that detects such computations. Our profiler reveals that for four different websites, only 45% of dynamically executed instructions are useful in rendering the main page, on average. We then analyze and categorize unnecessary computations. Our analysis shows that processing JavaScript codes is the most notable category of unnecessary computations, specifically during page loading. Therefore, such computations are either completely wasted or could be deferred to a later time, i.e., when they are actually needed, thereby providing higher performance and better energy efficiency.