Message number check and message rearranging are basic theory concerning rollback recovery of distributed systems. In previous studies, the consistency of global state is based on the analysis of the dependency relations of message receipt and sending events. To simplify the determination of the global state consistency issue, we proposed message number check theory. Under the FIFO reliable channel assumption, the consistence of global state, can be determined by the number of messages sent and received by each process. In optimistic message protocols, the receipt order of unlogged messages...