Improving the Java memory model using CRF

This paper describes alternative memory semantics for Java programs using a n enriched version of the Commit/Reconcile/Fence (CRF) memory model [16]. I t outlines a set of reasonable practices for safe multithreaded programming in Java. Our semantics allow a number of optimizations such as load reorde ring that are currently prohibited. Simple thread-local algebraic rules exp ress the effects of optimizations at the source or bytecode level. The rule s focus on reordering source-level operations; they yield a simple dependen cy analysis algorithm for Java. An instruction-by-instruction translation o f Java memory operations into CRF operations captures thread interactions p recisely. The fine-grained synchronization of CRF means the algebraic rules are easily derived from the translation. CRF can be mapped directly to a m odem architecture, and is thus a suitable target for optimizing memory cohe rence during code generation.