1 Reply Latest reply: Aug 9, 2011 11:28 AM by 802316 RSS

    survivor spaces

    user50021
      Hello,

      we have a problem with heap sizing, in fact much more objects as expected survive enough young gcs to end up in the old heap where the finally become garbage. Since we have to use CMS we get a very fragmented old heap after a few hours and finally we see "concurent mode failure". To find the root cause we have to understand the aging of our objects. Is there a way to figure out which objects filling up the survivor space, e.g. a kind of "selective heap dump"? Thanks.

      regards,
      Ruediger
        • 1. Re: survivor spaces
          802316
          I would have a look at the live objects in the heap.

          I would start with the following to get the most objects first.
          jmap -histo:live {pid}
          Another thing I would do is increase the young generation. I tend to start with 8 GB new size and see how the system behaves and reduce the young generation if its not needed.