title: Growth in old gen memory usage always means memory leak in Java?
body: <p>We have several VMs which are running data service in production, client sends Restful HTTP requests to data service, the load is kind of heavy (500 requests per second per host in general) and load is always balanced on each VM. We have same configuration on all hosts (2 CPUs, <code>-Xms2048m -Xmx4096m -XX:MaxPermSize=192m -XX:NewSize=512m -XX:MaxNewSize=512M -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:+HeapDumpOnOutOfMemoryError</code>)</p>
  <p>Two days ago, we saw old gen heap usage start growing on 5 of those VMs (300 MB per day), old gen heap usage on other ones stay the same (around 80 MB), we are trying to identify the root cause, may I ask if this is a memory leak issue or just a normal situation? Does growth in old gen memory usage always mean memory leak in Java?</p>
  <p>Thanks.</p>
  <p>Update: We just restarted those 5 hosts yesterday, old gen heap usage on all of them went back to normal as other ones, however, after the peak load we had this morning, the old gen heap usage on one of them started growing again...</p>