METHOD AND SYSTEM FOR REPLICATION SUPPORTED IN A REMOTE METHOD INVOCATION SYSTEM

摘要

Replica of a server by reliably and ordering delivery of client requests through a deterministic and preemptive scheduler in a computer network with at least one client connected to the replicated server and through an ordered multicast protocol. Methods and systems are disclosed for enhancing consistency between the two. The scheduler observes an execution sequence that matches the order of requests determined by the multicast protocol. The deterministic scheduler subdivides the execution streams into instruction slices so that the number of instructions in each slice is predefined. One thread is scheduled at the start of one instruction slice, so that all scheduling decisions are the same for all server replicas. Thus, if all scheduling decisions are the same everywhere, the nondeterministic factors due to the time-based scheduling of a typical thread scheduler are eliminated. The deterministic scheduler also accepts new client requests and creates a thread for every m instruction slices using the admission control window while waiting for a new multicast request. The new multicast may not contain any new requests, in which case the scheduler will continue to schedule the current threads. Otherwise, the thread scheduler accepts new requests, creates new threads, and executes them in the order specified by the multicast protocol.