Reliable distributed processing system

Abstract

A method and apparatus for implementing a highly reliable distributed processing system. The group of processors of the system are linked in a circular list, the final processor being linked to the first processor. Only one of the processors is a lead processor, and has the “Watchdog” data required of a lead processor. Only a lead processor can seize a global resource, and only a lead processor can switch another processor out of service. The successor processor to the lead processor contains a Ghost Object token, which is initially identical to the contents of the Watchdog token, except for an indication that it is a Ghost Object token. This next processor times from the time that it receives the Ghost Object token to insure that it will receive the Watchdog token within a pre-determined time. If it fails to receive the Watchdog token by the end of the time-out, it converts the Ghost Object token to a Watchdog token, and sends a new Ghost Object token to its own successor processor. Eventually, one of the successor processors tests the processor which timed-out, to insure that it is still operative, and if necessary, switches that processor out of service and changed the linkage of the list of processors to by-pass the processor that has been switched out of service. Advantageously, this arrangement allows for a highly reliable distributed multi-processing system without requiring extra hardware.

Dependencies are inferred from the claim text.