LifeLine: An Object-Page Lifetime Alignment GC Enabling Minimal Memory Copying for Mobile Devices

LifeLine is a garbage collection (GC) framework for Android that tackles the fundamental object–page lifetime mismatch. Existing copying collectors move objects, while the OS manages pages; mixed lifetimes within a page force excessive object copying instead of efficient page remapping. LifeLine explicitly aligns object lifetimes with physical pages via three components. First, lifetime-based graph partitioning monitors reference updates and partitions the object graph into subgraphs with strong lifetime affinity. Second, lifetime-aligned GC packs these subgraphs into pages so that each page contains almost entirely live or dead objects, enabling effective page-level management. Third, near-zero-copy GC exploits this bimodal per-page liveness by remapping mostly-live pages and copying only the few surviving objects from mostly-dead pages in cooperation with the OS. Implemented in the Android Runtime and evaluated on real smartphones and popular mobile applications, LifeLine significantly cuts GC copy volume by 57.4%, reduces GC time by 22.7% on average, and improves user-visible responsiveness with modest CPU and memory overhead.