No, the JMM specification is not vague. Abridged, it provides a minimum set of guarantees in terms of data visibility between threads -happens-before rules- tha

No, the JMM specification is not vague. Abridged, it provides a minimum set of guarantees in terms of data visibility between threads -happens-before rules- that the application programmer can expect. Think of it as an abstraction layer that portrays an uniform view of the myriad of hardware configurations on which the JVM runs -e.g. cache coherence strategies-, thus relieving the programmer from the burden of knowing the nuts and bolts of the target system for which its code is intended.