Optimistic Approach
Need not determine when it is safe to proceed; instead they determine when an error has occurred, and invoke a procedure to recover.
Exploit more parallelism (speculative parallelism), and dynamic creation of logical processes can be easily accommodated.
The Time Warp mechanism, based on the Virtual Time paradigm, is the most well-known optimistic protocol.
Virtual time is synonymous with simulated time. In Time Warp, a causality error is detected whenever and event message is received that contain a timestamp smaller than that of the process's clock (i.e., the timestamp of the last processed message). The event causing rollback is called a straggler. Recovery is invoked to undo the effects of all events that have been processed prematurely by the process receiving the straggler.