Inlined objects (fields or flattened array elements) are dumped as HPROF_GC_INSTANCE_DUMP records and objectID for them are generated by special generator (as we cannot use addresses on the objects). The generator produces sequential numbers (1, 2, 3...)
But number of inlined objects can be huge and generator can produce the numbers which conflict with addresses of heap objects (which are used as IDs for this objects).
Also with JDK-8276171 objectID for instance objects can be small numbers.
Real java applications usually use only some part of the available heap address space.
Need to make the generator more flexible:
- detect safe address ranges (before/after the heap);
- estimate number of required objectID (i.e. number of inlined objects) to ensure they can fit 32 or 64bit objectID