Recoverable mutual exclusion with abortability

Abstract

In light of recent advances in non-volatile main memory technology, there has been a flurry of research in designing algorithms that are resilient to process crashes. As a result of main memory non-volatility, a process is allowed to crash any time during the execution, without affecting the state of the data stored in the main memory. With the assumption that a process eventually restarts after a crash, prior works have focused on designing mutual exclusion algorithms that use the non-volatile main memory to recover from such crashes. Such mutual exclusion algorithms that provide multiple processes with a mutually exclusive access to a shared resource in the presence of process crashes are called Recoverable Mutual Exclusion (RME) algorithms. We present the first RME algorithm where a process has the ability to abort executing the algorithm, if it decides to give up its request for a shared resource before being granted access to that resource. With n being the maximum number of processes for which the algorithm is designed, in the absence of a crash our algorithm guarantees a worst-case remote memory references (RMR) complexity of O(log n) per passage on the Distributed Shared Memory (DSM) machines, and a complexity of O(log n) or O(n) on Cache Coherent (CC) machines, depending on how caches are managed.