Abstract

Abstract-In systems of asynchronous processes using messagelists with SEND-RECEIVE primitives for interprocess communication recovery primitives are defined to perform state restoration: MARK saves a particular point in the execution of the program; RESTORE resets the system state to an earlier point (saved by MARK); and PURGE discards redundant information when it is no longer needed for possible state restoration. Errors may be propagated through the system, requiring state restoration also to be propagated. Different types of propagation of state restoration are identified. Data structures and procedures are sketched that Implement the recovery primitives. In ill-structured systems the domino effect can occur, resulting in a catastrophic avalanche of backup activity and causing many messagelist operations to be undone. Sufficient conditions are developed for a system to be domino-free. Explicit bounds on the amount of unnecessary restoration are determined for certain classes of systems, including systems where the sequence of recovery and messagelist primitives is described by the regular expression (MARK; RECEIVE*; SEND*)*. Index Terms-Backup, domino effect, error recovery, parallel backtralcking, process communication, recovery blocks, state restoration. I.

Citations

489	System Structure for Software Fault Tolerance - Randell
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2	to 1979, he was an Assistant Professor of Computer Science at the Indian Institute of Technology, Kanpur. From 1979 to 1985, he was an Assistant Professor of Computer Science at Rensselaer Polytechnic Institute - From - 1976
1	State restoration among communicating processes," Digital Syst - Russell - 1976
1	The domino effect in producer-consumer state restoration," in preparation - Rev
1	revised July 31 - March - 1979