Dynamic synchrony among atomic actions

Abstract

Synchrony continues to be an important concern in concurrent programming. Existing languages and models have introduced a great diversity of constructs for expressing and managing synchronization among sequential processes or atomic actions. This paper puts forth a model in which synchrony is viewed as a relation among atomic actions, a relation which may evolve with time. The model is shown to be convenient for expressing formally the semantics of synchrony as it appears in many of the languages and models proposed to date. Among such models Swarm is singled out for its use of dynamic synchrony. The Swarm notation is briefly reviewed. A new concurrent algorithm for the Leader Election problem provides a vehicle for illustrating the use of dynamic synchrony in Swarm.

Mobile UNITY

“…In the absence of any (synchronization) interactions, the actions corresponding to each individual program statement are enabled-this is the UNITY perspective. The coselection (a symmetric form of superposition) adds and removes, dynamically, actions corresponding to pairs of statements executed in parallel; the idea has its roots in the concept of dynamic synchrony [Roman et al 1993] originally introduced in the Swarm model [Roman and Cunningham 1992]. Similarly, an inhibition can be thought of as removing and restoring, dynamically, actions corresponding to singleton statements.…”