This paper outlines the design and implementation of the PEVM, a new scalable, high-performance implementation of orthogonal persistence for the Java platform (OPJ). The PEVM is based on the Sun Microsystems Laboratories Virtual Machine for Research, which features an optimizing Just-In-Time compiler, exact generational garbage collection, and fast thread synchronization. The PEVM also uses a new, scalable persistent object store designed to manage 80GB of objects. It is approximately ten times faster than previous OPJ implementations and can run signi cantly larger programs. Despite its greater speed and scalability, the PEVM's implementation is much simpler (e.g., just 43 % of the VM source patches needed by our previous OPJ implementation). This is largely due to the pointer swizzling strategy we chose, the ResearchVM's exact memory management, and simple but e ective mechanisms. For example, we implement some key data structures in the Java programming language since this automatically makes them persistent.

We describe how reachability-based orthogonal persistence can be supported even in uncooperative implementations of languages such as C++ and Modula-3, and without modification to the compiler. Our scheme extends Bartlett's mostly-copying garbage collector to manage both transient objects and resident persistent objects, and to compute the reachability closure necessary for stabilization of the persistent heap. It has been implemented in our prototype of reachability-based persistence for Modula-3, yielding performance competitive with that of comparable, but non-orthogonal, persistent variants of C++. Experimental results, using the OO7 object database benchmarks, reveal that the mostly-copying approach offers a straightforward path to efficient orthogonal persistence in these uncooperative environments. The results also characterize the performance of persistence implementations based on virtual memory protection primitives. 1 Introduction Incorporating orthogonal persistence [11] ...

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