Heap memory address values ​​in GC logs using -XX: + PrintHeapAtGC?

Question

The Java heap is divided into regions known as generations , for example. a new generation that can be further divided, for example. eden. Using the -XX:+PrintHeapAtGCJVM option , three memory addresses for each heap area are printed in the GC logs in the form [A, B, C), where A, Band Care memory addresses, for example:

eden space 838912K, 100% used [0x000000073ae00000, 0x000000076e140000, 0x000000076e140000)

What is the meaning of these memory addresses?

I searched the Internet but could not find an explanation for this part of the GC logs.

Answer 1

A (bottom) - ;
B (top) - ;
C (end) - .

.

space.hpp:

// Size computations: sizes in bytes.
size_t capacity() const        { return byte_size(bottom(), end()); }
size_t used() const            { return byte_size(bottom(), top()); }
size_t free() const            { return byte_size(top(),    end()); }

space.cpp:

void ContiguousSpace::print_on(outputStream* st) const {
  print_short_on(st);
  st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
                bottom(), top(), end());
}