title: Why does park/unpark have 60% CPU usage?
body: <p>Recently we started stress testing our application (an XMPP based chat server) using YJP 11.0.9. During our test we noticed following strange behavior.</p>
  
  <ol>
  <li>Sampling shows sun.misc.Unsafe.unpark(Object) took 60% of CPU.</li>
  <li>For the same app Tracing shows that LockSupport.park(Object) took 52% of CPU.</li>
  </ol>
  
  <p>I did multiple tests to confirm results and every time I got similar results.</p>
  
  <p>I am unable to understand why unpark should take 60% time and why tracing shows exactly opposite results.</p>
  
  <p>Can someone help me understand these results. Am I missing something here?</p>
  
  <p>Environment: </p>
  
  <pre>java -version
  java version "1.6.0_31"
  Java(TM) SE Runtime Environment (build 1.6.0_31-b04)
  Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01, mixed mode)</pre>