Why is volatile not considered useful in multithreaded C or C++ programming?

Question

As demonstrated in this answer I recently posted, I seem to be confused about the utility (or lack thereof) of volatile in multi-threaded programming contexts.<

Answer 1

This is all that "volatile" is doing: "Hey compiler, this variable could change AT ANY MOMENT (on any clock tick) even if there are NO LOCAL INSTRUCTIONS acting on it. Do NOT cache this value in a register."

That is IT. It tells the compiler that your value is, well, volatile- this value may be altered at any moment by external logic (another thread, another process, the Kernel, etc.). It exists more or less solely to suppress compiler optimizations that will silently cache a value in a register that it is inherently unsafe to EVER cache.

You may encounter articles like "Dr. Dobbs" that pitch volatile as some panacea for multi-threaded programming. His approach isn't totally devoid of merit, but it has the fundamental flaw of making an object's users responsible for its thread-safety, which tends to have the same issues as other violations of encapsulation.