title: Thread safe Hash Map?
body: <p>I am writing an application which will return a HashMap to user. User will get reference to this MAP.
  On the backend, I will be running some threads which will update the Map.</p>
  
  <p><strong>What I have done so far?</strong></p>
  
  <hr>
  
  <p>I have made all the backend threads so share a common channel to update the MAP. So at backend I am sure that concurrent write operation will not be an issue.</p>
  
  <hr>
  
  <p><strong>Issues I am having</strong></p>
  
  <hr>
  
  <ol>
  <li>If user tries to update the MAP and simultaneously MAP is being updated at backend --> Concurrent write operation problem.</li>
  <li>If use tries to read something from MAP and simultaneously MAP is being updated at backend --> concurrent READ and WRITE Operation problem.</li>
  </ol>
  
  <p>Untill now I have not face any such issue, but i m afraid that i may face in future. Please give sugesstions.</p>
  
  <p>I am using <code>ConcurrentHashMap&lt;String, String&gt;.</code></p>