volatile bool引发的知识点

使用这个关键字，可以防止将变量存到寄存器中，达到编译器优化，每次都从内存中读取变量的值。

volatile bool是否是线程安全的呢？

volatile can be used for such purposes. However this is an extension to standard C++ by Microsoft:

Microsoft Specific

Objects declared as volatile are (...)

• A write to a volatile object (volatile write) has Release semantics; (...)
• A read of a volatile object (volatile read) has Acquire semantics; (...)

This allows volatile objects to be used for memory locks and releases in multithreaded applications.(emph. added)

That is, as far as I understand, when you use the Visual C++ compiler, a volatile bool is for most practical purposes an atomic<bool>.

从上面的解答看出，volatile bool类似于 atomic<bool>。