A dynamic analysis to support object-sharing code refactorings

Creation of large numbers of co-existing long-lived isomorphic objects increases the memory footprint of applications significantly. In this paper we propose a dynamic-analysis based approach that detects allocation sites that create large numbers of long-lived isomorphic objects, estimates quantitatively the memory savings to be obtained by sharing isomorphic objects created at these sites, and also checks whether certain necessary conditions for safely employing object sharing hold. We have implemented our approach as a tool, and have conducted experiments on several real-life Java benchmarks. The results from our experiments indicate that in real benchmarks a significant amount of heap memory, ranging up to 37% in some benchmarks, can be saved by employing object sharing. We have also validated the precision of estimates from our tool by comparing these with actual savings obtained upon introducing object-sharing at selected sites in the real benchmarks.