Effects Of False Sharing And Locality On Object Layout Optimization For Multi-Threaded Applications

One approach to decrease the gap between memory latency and processor speed is improving locality of data. Data layout optimization is a way to increase locality by reordering data elements in memory. Unfortunately, for multi-threaded applications, the issue is more complex due to the effects of false sharing. In this paper, the effect of locality and false sharing on multi-threaded applications is investigated. Therefore, fields are reordered inside Java objects in such a way that improves the locality of reference among them and also decreases the estimated probability of false sharing. Considering the role of the JVM in laying out Java objects fields, IBM's JVM is modified with the ability to reorganize fields based on the profiled information.