Multi-dimensional locks with on-line allocation schemes

Synchronization is inherent to parallel computing and comprises many aspects. One aspect is the access control to shared data, especially important in MIMD shared-memory architectures. Several locking mechanisms have been proposed to perform this task. Most of these schemes rely on very little hardware support, such as atomic read-modify-write operations. Today, the amount of hardware required to implement a locking mechanism is not a major constraint and will be even less important in the future. This makes it interesting to investigate schemes with more flexibility, better performance, and improved ease of use, that rely more on hardware assisted circuits than previous suggestions. In this paper multi-dimensional locking schemes that allocate locks on-line are presented. A lock is assigned to the access control of a data structure only during the time this structure needs to be locked. Three specific schemes are proposed. Two offer the possibility of locking sub-structures within multi-dimensional arrays. All three schemes protect locked structures against accesses of misbehaving threads.