We propose a new algorithm that is effective for objects that are shared among threads but are not contended for in SMP environments. We can remove the overhead of the serialization between lock and other non-lock operations and avoid the latency of complex atomic operations in most cases. We established the safety of the algorithm by using a software tool called Spin. The experimental results from our benchmarking on an SMP machine using Intel Xeon processors revealed that our algorithm could significantly improve efficiency by 80% on average compared to using complex atomic instruction.