title: How to determine the cause of young gc of a Java application
body: <p>Recently I found it had a frequent young gc in my java app. Since I had a 1600M young generation, and it did young gc every 10 seconds, I think there are too many unnecessary Objects that cause these gcs.</p>
  
  <p>I know I can use jmap to do a heapdump to find out what cause full gc. But how can I find out what's in the young gen (cause a heapdump should clean the young gen and the young gen is varying all the time)</p>
  
  <p>And another question : Will jstat -gcutil increase the gc frequency?</p>