title: Does readFile caches the content?
body: <p>Say I have:</p>
  
  <pre><code>var fs = require('fs');
  var a= fs.readFile(__dirname + '/someBigFile.txt', function(err, data) {
      console.log(data);
  });
  </code></pre>
  
  <p>I've noticed that, if it first takes, say, 2 seconds to read <code>someBigFile</code>, now it takes several milliseconds. Is there some internal caching is Node.js happening when you read it multiple times? for example:</p>
  
  <pre><code>for(var i =0; i &lt; 10000; i++)
  {
      var greet = fs.readFile(__dirname + '/greet.txt', "utf-8", function(err, data) {
      });
  }
  </code></pre>