An efficient meta-lock for implementing ubiquitous synchronization

Programs written in concurrent object-oriented languages, especially ones t hat employ thread-safe reusable class libraries, can execute synchronizatio n operations (lock, notify, etc.) at an amazing rate. Unless implemented wi th utmost care, synchronization can become a performance bottleneck. Furthe rmore, in languages where every object may have its own monitor, per-object space overhead must be minimized. To address these concerns, we have devel oped a meta-lock to mediate access to synchronization data. The meta-lock i s fast (lock + unlock executes in 11 SPARC(TM) architecture instructions), compact (uses only two bits of space), robust under contention (no busy-wai ting), and flexible (supports a variety of higher-level synchronization ope rations). We have validated the meta-lock with an implementation of the syn chronization operations in a high-performance product-quality Java(TM) virt ual machine and report performance data for several large programs.