Patent ID: 6574665
Filing Date: 2003-06-03
Classification: G06F,H04L

Abstract:
A hierarchical vector clock method of detecting a causal precedence relation between events in an asynchronous distributed system, said system comprising:a plurality of processes each of which is executing on a separate physical node and exchanging information with other processes by transmitting messages over a communications network connecting the nodes, said events including message receive events and message send events, said processes of the distributed system being hierarchically grouped on two or more hierarchy levels, wherein: each hierarchy level comprises one or more peer groups; each peer group comprises one or more logical nodes; the processes are the logical nodes of the lowest hierarchy level; and each logical node of an (i+1)-th hierarchy level represents a peer group of an i-th hierarchy level, where i&gE;1, said method comprising: maintaining logical time in each individual process, said logical time comprising a plurality of integer vectors, one said vector for each hierarchy level in the distributed system, each of said vectors having a size equal to the number of said logical nodes in said peer group of logical nodes on the respective hierarchy level.