Efficient Memory Management for Lock-Free Data Structures with Optimistic Access

Abstract

Lock-free data structures achieve high responsiveness, aid scalability, and avoid deadlocks and livelocks. But providing memory management support for such data structures without foiling their progress guarantees is difficult. Often, designers employ the hazard pointers technique, which may impose a high performance overhead.In this work we propose a novel memory management scheme for lock-free data structures called optimistic access. This scheme provides efficient support for lock-free data structures that can be presented in a normalized form. Our novel memory manager breaks the traditional memory management invariant which never lets a program touch reclaimed memory. In other words, it allows the memory manager to reclaim objects that may still be accessed later by concurrently running threads. This broken invariant provides an opportunity to obtain high parallelism with excellent performance, but it also requires a careful design. The optimistic access memory management scheme is easy to employ and we implemented it for a linked list, a hash table, and a skip list. Measurements show that it dramatically outperforms known memory reclamation methods.