Pretenuring in Java by Object Lifetime and Reference Density Using Scratch-Pad Memory

Java has become a popular paradigm in software development. It is widely used in embedded systems and network computing because of its excellent robustness, modularity and security. Its built-in garbage collection automatically reclaims unused memory space. Current generational garbage collector works well with programs containing massive shortlived objects. However, the existence of hot-mature (i.e. frequently-accessed and long-lived) objects inhibits object reclamation. In this paper, we present two methodologies to exploit the locality for these objects. Firstly, we employ an on-chip scratchpad memory in memory hierarchy to preserve young and hot-mature objects. This reduces energy consumption and data accessing cycles for Java execution. Secondly, we introduce a pretenuring technique to segregate objects into separated memory regions based on the object lifetimes and reference densities, which minimizes the amount of object copying during garbage collections