title: Map vs Unordered_map-- Multithreading
body: <p>I have the following requirements:</p>
  
  <p>I need a datastructure with key,value pairs(keys are integers if that helps).</p>
  
  <p>I need the below operations:-</p>
  
  <ol>
  <li>Iteration(most used)</li>
  <li>Insertion (2nd most used)</li>
  <li>Searching by key and deletion(least)</li>
  </ol>
  
  <p>I plan to use multiple locks over the structure for concurrent access. 
  What is the ideal data structure to use?</p>
  
  <p>Map or an unordered map?</p>
  
  <p>I think unordered map makes sense, because i can insert in O(1), delete in O(1). But i am not sure of the iteration. How bad is the performance when compared to map? </p>
  
  <p>Also, i plan to use multiple locks on blocks instead of the whole structure. Any good implementation example of this?</p>
  
  <p>Thanks </p>