title: java flight recorder concatenation error
body: <p>i'm using java 7's flight recorder to dump  execution of Hadoop tasks.  to do this, i use this configuration option:</p>
  
  <pre><code>&lt;property&gt;
      &lt;name&gt;mapred.child.java.opts&lt;/name&gt;
      &lt;value&gt;-XX:+UnlockCommercialFeatures -XX:+FlightRecorder -XX:FlightRecorderOptions=defaultrecording=true,dumponexit=true,dumponexitpath=/root/recordings&lt;/value&gt;
  &lt;/property&gt;
  </code></pre>
  
  <p>The result is many .jfr files (as expected).  I can open anyone of these in Java Mission Control without issue.  However, if I try and concatenate them together using: </p>
  
  <pre><code>java oracle.jrockit.jfr.tools.ConCatRepository [directory] [-o output_filename] 
  </code></pre>
  
  <p>(taken from: <a href="http://docs.oracle.com/cd/E15289_01/doc.40/e15070.pdf" rel="nofollow">http://docs.oracle.com/cd/E15289_01/doc.40/e15070.pdf</a>: <a href="http://docs.oracle.com/cd/E15289_01/doc.40/e15070.pdf" rel="nofollow">http://docs.oracle.com/cd/E15289_01/doc.40/e15070.pdf</a>)</p>
  
  <p>I can not open the result in Java Mission Control with error "Loading events from condensed.jfr has encountered a problem.  Could not load events from condensed.jfr".  </p>
  
  <p>What am I doing wrong?</p>