Implementing atomic actions on decentralized data (Extended Abstract)

In this paper, a new approach to coordinating accesses to shared data objects is described. We have observed that synchronization of accesses to shared data and recovering the state of such data in the case of failures are really two sides of the same problem—implementing atomic actions on multiple data items. We describe a mechanism that solves both problems simultaneously in a way that is compatible with requirements of decentralized systems. In particular, the correct construction of a new atomic action can be done without knowledge of all other atomic actions in the system that might execute concurrently. Further, the mechanisms degrade gracefully if parts of the system fail—only those atomic actions that require resources in failed parts of the system are prevented from executing.