摘要

Developing concurrent software that is both correct and efficient is challenging. Past research has proposed various techniques that support developers in finding, understanding, and repairing concurrency-related correctness problems, such as missing or incorrect synchronization. In contrast, existing work provides little support for dealing with concurrency-related performance problems, such as unnecessary or inefficient synchronization. This paper presents SyncProf, a profiling approach that helps in identifying, localizing, and repairing performance bottlenecks in concurrent programs. The approach consists of a sequence of dynamic analyses that reason about relevant code locations with increasing precision while narrowing down performance problems and gathering data for avoiding them. A key novelty is a graph-based representation of relations between critical sections, which is the basis for computing the performance impact of a critical section and for identifying the root cause of a bottleneck. Once a bottleneck is identified, SyncProf searches for a suitable optimization strategy to avoid the problem, increasing the level of automation when repairing performance bottlenecks over a traditional, manual approach. We evaluate SyncProf on 25 versions of eleven C/C++ projects with both known and previously unknown synchronization bottlenecks. The results show that SyncProf effectively localizes the root causes of these bottlenecks with higher precision than a state of the art lock contention profiler, and that it suggests valuable strategies to repair the bottlenecks.

  • 出版日期2018-10