title: Monitor Tomcat Webapp
body: <p>I have a Tomcat webapp running on Amazon EC2. I am expecting heavy usage of the webapp in the future and is therefore trying to understand how to monitor webapp and ensure it is   working well.</p>
  
  <p>The Amazon EC2 shows the following <em>Cloudwatch Metrics</em> for each EC2 instance </p>
  
  <ol>
  <li>Avg CPU Utilization</li>
  <li>Avg Disk Reads</li>
  <li>Sum Disk Read Ops (Count)</li>
  <li>Avg Disk Writes</li>
  <li>Sum Disk Writes Ops (Count)</li>
  <li>Max Network Ins</li>
  <li>Max Network Outs</li>
  <li>Sum Status (Any)</li>
  <li>Sum Status Instance
  10.Sum Status System</li>
  </ol>
  
  <p>I have also found a library <a href="https://github.com/codahale/metrics" rel="nofollow">Metrics</a>, which can be used for monitoring JVM but I have not be able to understand the idea complete of what should I be monitoring and why?</p>
  
  <p><strong>My Question</strong></p>
  
  <p>What and why should be I monitoring to ensure my Tomcat Webapp works fine when sudden increase in user load on server?</p>