Dynamic monitor allocation in the Java virtual machine.

With the Java language and sandboxed environments becoming more and more popular research needs to be conducted into improving the performance of these environments while decreasing their memory footprints. In this paper we present a dynamic approach for growing monitors for objects in order to reduce the memory footprint and improve the execution time of the IBM Java Virtual Machine. According to the Java Language Specification every object needs a monitor, however not all objects require synchronization, thus the monitor can have a negative memory impact. Our new approach grows monitors only when required. The impact of this approach on performance and memory has been evaluated using the SPECjbb2005 benchmark and future work is also discussed. On average a performance increase of 0.47% and a memory reduction of about 5.51% has been achieved with our approach.