The bug is found by running JDK 8 b109 inside valgrind

The various Arena constructor calls set_size_in_bytes(), like:

Arena::Arena() {
  _first = _chunk = new (AllocFailStrategy::EXIT_OOM, Chunk::init_size) Chunk(Chunk::init_size);
  _hwm = _chunk->bottom();      // Save the cached hwm, max
  _max = _chunk->top();
  set_size_in_bytes(Chunk::init_size);
  NOT_PRODUCT(Atomic::inc(&_instance_count);)
}

void Arena::set_size_in_bytes(size_t size) {
  if (_size_in_bytes != size) {
    _size_in_bytes = size;
    MemTracker::record_arena_size((address)this, size);
  }
}

However, at this time, the _size_in_bytes field is not yet initialized, (and it might be equal to size just by chance).

The fix would be have a different method like

void Arena::init_size_in_bytes(size_t size) {
  _size_in_bytes = size;
  MemTracker::record_arena_size((address)this, size);
}

This should be fixed because it generates a lot of error messages inside valgrind.