Partial Snapshot Objects

We introduce a generalization of the atomic snapshot object, which we call the partial snapshot object. This object stores a vector of values. Processes may write components of the vector individually or atomically scan any subset of the components. We investigate implementations of the latter partial scan operation that are more efficient than the complete scans of traditional snapshot objects. We present an algorithm that is based on a new implementation of the active set abstraction, which may be of independent interest.