Adaptive selection of necessary and sufficient checkpoints for dynamic verification of temporal constraints in grid workflow systems

摘要

In grid workflow systems, a checkpoint selection strategy is responsible for selecting checkpoints for conducting temporal verification at the runtime execution stage. Existing representative checkpoint selection strategies often select some unnecessary checkpoints and omit some necessary ones because they cannot adapt to the dynamics and uncertainty of runtime activity completion duration. In this article, based on the dynamics and uncertainty of runtime activity completion duration, we develop a novel checkpoint selection strategy that can adaptively select not only necessary, but also sufficient checkpoints. Specifically, we introduce a new concept of minimum time redundancy as a key reference parameter for checkpoint selection. An important feature of minimum time redundancy is that it can adapt to the dynamics and uncertainty of runtime activity completion duration. We develop a method on how to achieve minimum time redundancy dynamically along grid workflow execution and investigate its relationships with temporal consistency. Based on the method and the relationships, we present our strategy and rigorously prove its necessity and sufficiency. The simulation evaluation further demonstrates experimentally such necessity and sufficiency and its significant improvement on checkpoint selection over other representative strategies.