Comparison of Memory Allocation in the Jamaica and Oracle Java Virtual Machine

This master's thesis compares the memory allocation between the two virtual machines, namely Oracle and Jamaica VM. The basic difference of the architecture in both machines is that the Jamaica VM uses fixed-size blocks for allocating objects on the heap. This means that objects have to be split into several connected blocks if they become bigger than the block-size. This produces more overhead in garbage collection in terms time and memory. The thesis contains both theoretical and experimental analysis on the overhead of time and memory and attempts to find an answer to the question of which block-size would be recommended for any given program. The theoretical analysis is based on specifications of the two virtual machines and the experimental analysis is done with a modified JVMTI Agent together with the SPECjvm2008 Benchmark and specially designed ReadTextFileBenchmark. The results are summarized in a diagram. From this diagram, recommendation on the block size can be made for any specific data size.