I think I know what you mean, but that's a very dangerous way to word it when speaking in public. It would be more correct to say that "all you need to guarantee reads are protected by memory barriers is volatile."

The distinction matters because, to someone who doesn't already know all about volatile, the way you worded it might lead them to believe that `x++;` is an atomic statement if x is volatile, which is not true. That's a specific example of where things like atomic types are necessary.

(For the curious: https://www.baeldung.com/java-atomic-variables)

I think maybe what you're missing about what I'm saying is that I'm trying to mainly talk for the benefit of people who don't have a solid understanding of how to do safe and performant multithreading. Which is the vast majority of programmers. For that sort of audience, I tend to agree with dragontamer that "just use a mutex" is probably the safest advice to start out. Producing results faster doesn't count for much if you're producing wrong results faster.

In C++, you'd have to use OS-specific + compiler-specific routines like InterlockedIncrement64 to get guarantees about when or how it was safe to read/write variables.

Not anymore of course: C++11 provides us with atomic-load and atomic-store routines with the proper acquire / release barriers (and seq-cst default access very similar to Java's volatile semantics).

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Anyway, put yourself into the mindset of a 2009-era C++ programmer for a sec. InterlockedIncrement works on Windows but not in Linux. You got atomics on GCC, but they don't work the same as Visual Studio atomics.

Answer: Mutex lock and mutex-unlock. And then condition variables for polling. Yeah, its slower than InterlockedIncrement / seq-cst atomic variables with proper memory barriers, but it works and is reasonably portable. (Well, CriticalSections on Windows because I never found a good pthreads library for Windows)

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Its still relevant because you still see these thread issues come up in old C++ code.