class Concurrent::Collection::AtomicReferenceMapBackend

def check_for_resize

resize is already needed because resizings are lagging additions.
transfers bins. Rechecks occupancy after a transfer to see if another
If table is too small and not already resizing, creates next table and 
def check_for_resize
  while (current_table = table) && MAX_CAPACITY > (table_size = current_table.size) && NOW_RESIZING != (size_ctrl = size_control) && size_ctrl < @counter.sum
    try_in_resize_lock(current_table, size_ctrl) do
      self.table = rebuild(current_table)
      (table_size << 1) - (table_size >> 1) # 75% load factor
    end
  end
end