Provide a low-overhead way of sampling Java heap allocations, accessible via JVMTI ([JEP 331](http://openjdk.java.net/jeps/331)).

It is designed to meet the following goals:
  - Low-overhead enough to be continuously enabled by default
  - Accessible via a well-defined, programmatic interface (JVMTI)
  - Can sample all allocations (that is, not limited to allocations that are in one particular heap region or that were allocated in one particular way)
  - Can be defined in an implementation-independent way (that is, without relying on any particular GC algorithm or VM implementation)
  - Can give information about both live and dead Java objects