1. A method of operating a computing machine, the method comprising: instantiating a data structure in memory; and executing operations that, when executed on respective one or more processors that access the memory, provide concurrent obstruction-free operations, including state modifying operations, on the data structure, wherein the obstruction-free operations are linearizable and non-blocking, but do not themselves ensure progress in the presence of contention; and employing at least one contention management mechanism that facilitates progress of a computation that employs the obstruction-free operations, wherein semantics of the obstruction-free operations is independent of the contention management mechanism.