There is a saying in the community: “Cherish life, stay away from barriers,” which sufficiently illustrates that memory barriers are quite obscure and difficult to grasp accurately. Using too weak a barrier can lead to software instability, while using too strong a barrier can cause performance issues. Therefore, in engineering, the goal is to pursue a barrier that is just right, neither too strong nor too weak. This article aims to explain the most obscure principles of memory barriers in the simplest language, and it will also provide five engineering case studies, …