Accelerating sequential consistency for Java with speculative compilation

Abstract

A memory consistency model (or simply a memory model) specifies the granularity and the order in which memory accesses by one thread become visible to other threads in the program. We previously proposed the volatile-by-default (VBD) memory model as a natural form of sequential consistency (SC) for Java. VBD is significantly stronger than the Java memory model (JMM) and incurs relatively modest overheads in a modified HotSpot JVM running on Intel x86 hardware. However, the x86 memory model is already quite close to SC. It is expected that the cost of VBD will be much higher on the other widely used hardware platform today, namely ARM, whose memory model is very weak.