class Concurrent::Collection::AtomicReferenceMapBackend

def initialize(options = nil)
  super()
  @counter = Concurrent::ThreadSafe::Util::Adder.new
  initial_capacity  = options && options[:initial_capacity] || DEFAULT_CAPACITY
  self.size_control = (capacity = table_size_for(initial_capacity)) > MAX_CAPACITY ? MAX_CAPACITY : capacity
end