Using Message Semantics to Reduce Rollback in Optimistic Message Logging Recovery Schemes

Recovery from failures can be achieved through asyn-chronous checkpointing and optimistic message logging. These schemes have low overheads during failure-free operations. Central to these protocols is the determination of a maximal consistent global state, which is recoverable. Message semantics is not exploited in most existing recovery protocols to determine the recoverable state. We propose to identify messages that are not innuential in a computation through message semantics. These messages can be logically removed from the computation without changing its meaning or result. We show that considering these messages in the recoverable state computation gives rise to re-coverable states that dominate the recoverable state deened under conventional model. We then develop an algorithm for identifying these messages. This technique can also be applied to ensure a more timely commitment for output in a distributed computation.