A two-phase escape analysis for parallel Java programs

Thread escape analysis conservatively determines which objects may be accessed in more than one thread. Thread escape analysis is useful for a variety of purposes — finding races in multi-threaded programs, removing useless synchronization, allocating data to thread-local heaps, and compiling to target more strict consistency models. Thread escape analyses are often interprocedural, and interprocedural analyses are generally either too slow to perform at runtime in dynamic systems, or trade-off significant amounts of precision for speed. This paper describes a two-phase offline/online interprocedural and inter-thread escape analysis that is faster and more accurate, on average, than previously published analyses. By performing an offline pre-analysis followed by a dynamic online analysis that integrates offline results with dynamic information, significant improvements in performance and accuracy are achieved. For compiling Java programs under a sequentially consistent memory model, our approach enables application executions that are, on average, 1.5 times faster than those using the previous fastest online algorithm, with only 80% of the online compilation time.