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  1. JDK
  2. JDK-8224584 Shenandoah: Eliminate forwarding pointer word
  3. JDK-8225530

Release Note: Shenandoah eliminated separate forwarding pointer slot

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    Details

    • Type: Sub-task
    • Status: Closed
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 13
    • Fix Version/s: 13
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc

      Description

      Shenandoah uses an extra word per object to store the forwarding pointer of an object in support of concurrent evacuation. With the arrival of load reference barriers, it is possible to store the forwarding pointer in the then-unused memory of old copy of an object instead, for example use the old copy mark-word and encode the forwarding pointer there. This allows to eliminate the extra forwarding pointer word, and thus reduces memory footprint to that of regular GC.

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            Assignee:
            shade Aleksey Shipilev
            Reporter:
            shade Aleksey Shipilev
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              Created:
              Updated:
              Resolved: