A Study on Object Lifetime in GC of Android Applications

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 investigate objects' lifetime trend in modern Java-based applications of Android, and discuss a method for improving GC based on this trend. First, we introduce our monitoring system for object creations and collections in ART. Second, we present the monitoring results of recent popular Android applications and reveal the relations between lifetimes and object sizes.