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  1. JDK
  2. JDK-8005604

HPROF should report the actual instance size

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Details

    • Enhancement
    • Status: Closed
    • P4
    • Resolution: Won't Fix
    • None
    • tbd_minor
    • tools
    • None

    Description

      At this point, hprof dumper iterates the fields trying the deduce the instance size. However, this is prone to errors in estimations, because:
       a) object header sizes can be changed without notice;
       b) object fields can be aligned/padded for correctness/performance reasons

      We have already identified that with upcoming @Contended, hprof estimates can be terribly wrong, see:
      http://cs.oswego.edu/pipermail/concurrency-interest/2012-November/010276.html

      Luckily, VM already knows the exact instance size, and we can just reuse this info.

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            Unassigned Unassigned
            shade Aleksey Shipilev
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              Created:
              Updated:
              Resolved: