title: When should I use ConcurrentSkipListMap?
body: <p>In Java, <code>ConcurrentHashMap</code> is there for better <code>multithreading</code> solution. Then when should I use <code>ConcurrentSkipListMap</code>? Is it a redundancy?</p>
  
  <p>Does multithreading aspects between these two are common?</p>