title: Concurrent LinkedList vs ConcurrentLinkedQueue
body: <p>I need a concurrent list that is thread safe and at the same time is best for iteration and should return exact size.
  I want to to store auction bids for an item. So I want to be able to </p>
  
  <ol>
  <li>retrieve the exact number of bids for an item </li>
  <li>add a bid to a item </li>
  <li>retrieve all the bids for a given item.</li>
  <li>Remove a bid for a item</li>
  </ol>
  
  <p>I am planning to have it in a 
  <code>ConcurrentHashMap&lt;Item, LinkedList&lt;ItemBid&gt;&gt;</code> -- LinkedList is not thread safe but returns exact size
  <code>ConcurrentHashMap&lt;Item, ConcurrentLinkedQueue&lt;ItemBid&gt;&gt;</code> - concurrentlinked queue is thread safe but does not guarantee to return exact size </p>
  
  <p>Is there any other better collection that will address the above 4 points and is thread safe.</p>