C++ 14/17 memory model 
In this section, we will explore the definition and specification of the memory model for modern C++ (11, 14, and 17). We will investigate what it is, why it is needed for multi-threaded applications, and the important principles of the C++ memory model.
What is a memory model?
A memory model, a.k.a. a memory consistency model, specifies the allowed and expected behavior of multi-threaded applications that interact with shared memory. The memory model is the foundation of the concurrency semantics of shared memory systems. If there are two concurrent programs, one writing to and another reading from a shared memory space, the memory model defines the set of values that a read operation is allowed to return for any combination of reads and writes.
Implementation of the memory models (C++ or otherwise) must be constrained by the rules specified by the memory models, because if the outcome cannot be inferred from the order of reads and writes, then it...