title: 100% old generation - is it an issue?
body: <p>We are doing a load test of an application, and after some time AppDynamics reports <strong>"PS Old gen" at 100% in red</strong>. Full GC is running every 10 minutes. Memory's "Current Utilization" varies between <strong>70-90%</strong>, it goes like this for hours and never fails with OOM.</p>
  
  <p>I thought that once old gen utilization is above certain level, GC will try to free/compact old gen area and if nothing is freed it would either fail with OOM and start crazy full GC cycles just before it. However I don't see any of these. The application runs fine with 100% old gen utilization.</p>
  
  <p>We are using Oracle Java 7u14 (64b, 4 cpu cores, 10gb RAM) and JVM is configured with </p>
  
  <pre><code>-XX:+UseParallelOldGC -Xmx4g
  </code></pre>
  
  <p>Thank you!</p>