Efficiency of e-NR Labeling for On-the-fly Race Detection of Programs with Nested Parallelism

Abstract

On-the-fly race detector using Lamport's happened-before relation needs thread labeling scheme for generating unique identifiers which maintain logical concurrency information for the parallel thread. e-NR. labeling creates the NR labels by inheriting from the parent thread a pointer to their shared information, so it requires constant amount of time and space overhead on every fork/join operation. Previous work compares e-NR labeling only with OS labeling using a set of synthetic programs to support that e-NR labeling is efficient in detecting races during an execution of programs with nested parallelism. This paper compares empirically e-NR labeling with BD labeling that shows the same complexity of space and time with OS labeling. The results using OpenMP benchmarks with nested parallelism show that e-NR labeling is more efficient than T-BD labeling by at least 2 times in total monitoring time for race detection, and by at least 3 times in average space for maintaining thread labels.