On accrual failure detectors

Traditionally, failure detectors have considered a binary model whereby a given process can be either trusted or suspected. This paper defines a family of failure detectors, called accrual failure detectors, that revisits this interaction model. Accrual failure detectors associate to each process a real value representing a suspicion level. An important advantage of accrual failure detectors over binary ones is to allow distributed applications to trigger different actions depending on the suspicion level. For instance, an application can take precautionary measures when the suspicion level reaches a given level, and then take more drastic actions after it raises above a second (much higher) level. The paper defines accrual failure detectors and their basic properties. Four classes of accrual failure detectors are discussed, each of which is proved equivalent to a class of binary unreliable failure detectors (P, S, ◇P, and ◇S)リサーチレポート（北陸先端科学技術大学院大学情報科学研究科