Communication-induced determination of consistent snapshots

A classical way to determine consistent snapshots consists in using Chandy-Lamport´s (1985) algorithm. This algorithm relies on specific control messages that allow processes to synchronize local checkpoint determination and message recording in order that the resulting snapshot is consistent. This paper investigates a communication-induced approach to determine consistent snapshots. In such an approach, control information is carried by application messages. Two abstract necessary and sufficient conditions are stated: one associated with global checkpoint consistency, the other associated with message recording. A general protocol is derived from these abstract conditions. Actually, this general protocol can be instantiated in distinct ways, giving rise to a family of communication-induced snapshot protocols. This general protocol shows there is an intrinsic tradeoff between the number of forced checkpoints and the number of recorded messages. Finally, a particular instantiation of the general protocol is provided.