> This is a really good question. Each language adopts its own philosophical stance on the matter. Java is an excellent example of a language that tries to minimize undefined behavior, as much as C maximizes it. Even in the case of data races, the range of machine behavior is quite constrained (it can't break type safety, for example). This approach has some cost in performance, but Java is still performant. We don't need to worry much about programs breaking as Java compilers optimize more aggressively, although in earlier days there were sloppy programs that depended on the specific behavior of the specific JVM they were written on (see Cliff Click's writings for more on this).

The Java memory model is usually cited as a success, but it's success is far more qualified than it looks at first glance. The original memory model was horribly broken and no compiler actually implemented it. Java 5 introduced the modern memory model (in particular, the notion of data-race-free being the underlying basis for the memory model in the specification), but its attempts to pin down what could happen in the face of data-races is still inaccurate in terms of what compilers do and insufficient for what people would like them to be able to do. The C/C++ model of "controlled" data races in the forms of relaxed atomics (and, to a lesser degree, release/acquire and release/consume) are still considered incorrect and in active development.

I think Java is a terrific role model. Defining the multithreaded memory model was a long and painful process, but the end result is excellent.

It just doesn't quite fully fill the role of C for systems programming, as it uses GC rather than manual memory management.