Space reclamation for uncoordinated checkpointing in message-passing systems

Checkpointing and rollback recovery are techniques that can provide efficient recovery from transient process failures. In a message-passing system, the rollback of a message sender may cause the rollback of the corresponding receiver, and the system needs to roll back to a consistent set of checkpoints called the recovery line. If the processes are allowed to take uncoordinated checkpoints, the above rollback propagation may result in the domino effect which prevents recovery line progression. Traditionally, only obsolete checkpoints before the global recovery line can be discarded, and the necessary and sufficient condition for identifying all garbage checkpoints has remained an open problem.In this thesis, we derive a necessary and sufficient condition for achieving optimal garbage collection, and we prove that the number of useful checkpoints is in fact bounded by N(N + 1)/2 where N is the number of processes. Our approach is based on the maximum-sized antichain model of consistent global checkpoints and the technique of recovery line transformation and decomposition. We also show that, for systems requiring message logging to record in-transit messages, the same approach can be used to achieve optimal message log reclamation. As a final topic, we describe a unifying framework by considering checkpoint coordination and exploiting piecewise determinism as mechanisms for bounding rollback propagation, and demonstrate the applicability of the optimal garbage collection algorithm to domino-free recovery protocols.U of I OnlyETDs are only available to UIUC Users without author permissio