Object lifetime trend of modern Android applications for GC performance improvement

Abstract

Android operating system has become one of the most popular smartphone platforms. A large number of applications are developed for Android Runtime (ART). Garbage Collection (GC) is an essential function of ART for Java-based applications. GC suspends all the application threads, called Stop The World (STW), and sacrifices application's performance. For reducing pauses to check heap, generational GC was proposed. It separates objects into two groups, the objects which probably die in the next GC and the others. Then, it tries to reduce search space and time to check. With this GC, accurate estimation of object lifetime is important. In this paper, we explore trend of object lifetimes of modern Android application in order to improve estimation of lifetime of ART GC. For this purpose, we have constructed our application behavior monitoring system, which is called ART monitor. This is implemented by modifying Android and enable observation of creations and destruction of objects in ART. We have investigated the relation among object lifetime, object sizes, and object names in recent Android applications which are popular in Google Play Store. We than found that small object probably dies with short lifetime and objects of some classes always survive long time. Based on these findings, we discuss a method for improving ART GC performance.