title: Tomcat memory usage (PermGen)
body: <p>I am using Tomcat for deploying a web application withe following PermGen configurations:</p>
  
  <pre><code>JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 
  -server -Xms1536m -Xmx1536m
  -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m 
  -XX:MaxPermSize=256m -XX:+DisableExplicitGC"
  </code></pre>
  
  <p>Please I want to know the following:</p>
  
  <ol>
  <li>Is the whole memory used by Tomcat should be 256MB or Tomcat consumes other memory for other reasons ?</li>
  <li>How can I monitor the memory used by Tomcat to avoid reaching PemGen max size ?</li>
  </ol>
  
  <p>Also please be noticed that I have 3 Tomcats with the same previous PermGen configurations, running on the same physical server with 8 GB Ram which make me afraid of increasing PermGen max size to 512MB not to affect the physical server memory.</p>