title: Identify old gen in heap dump (or take heap dump of old gen only)
body: <p>I think I have a memory leak.<br>
  (they say the first step is admitting the problem, right?)</p>
  
  <p>Anyway, I think I do - see attached image for heap by regions: <img src="https://i.stack.imgur.com/BQGMW.png" alt="heap regions">.
  Green is Eden, blue/red is S0/S1, purple is old. I have unlimited tenuring (>15), lots of time passed between memory being allocated and it spilling to old gen. Hence - a memory leak. I think.</p>
  
  <p>So - the question - how can I analyze what is leaking? As you can see, my Eden is very active. Lot's of objects being created and destroyed all the time.</p>
  
  <p>Is there a way of taking a heap dump of the old gen only? Or somehow identify the old gen in a full heap dump (if so, with what tool)?</p>
  
  <p>Edit 1:
  Clarification: I'm not doing anything that <em>should</em> retain objects in memory. Everything I allocate after the initial startup should die young.</p>
  
  <p>Edit2:
  New findings: I took a heap dump, GCed like crazy and took another. The second one shows a significantly reduced level of old gen usage. The main difference between the two were objects held by finalizers.
  Don't finalizers run in young GC cycles? Do they always wait for a full GC to be cleaned?</p>