title: What is the reason behind not using ReenterantLock inside put method of ConcurrentHashMap
body: <p>Below is the code snippet of Java 8 ConcurrentHashMap for put method</p>
  
  <pre><code>else if ((fh = f.hash) == MOVED)
      tab = helpTransfer(tab, f);
  else {
      V oldVal = null;
      **synchronized (f) {**
      ...
  }
  </code></pre>