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  1. JDK
  2. JDK-8261501

Shenandoah: reconsider heap statistics memory ordering

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 8-shenandoah, 11.0.9, 16, 17
    • Fix Version/s: 17
    • Component/s: hotspot
    • Subcomponent:
      gc
    • Resolved In Build:
      b10

      Description

      ShenandoahHeap collects heap-wide statistics (used, committed, etc). It does so by atomically updating them with default CASes. Unfortunately, Hotspot's default for atomic operations is memory_order_conservative, which emits two-way memory fences around the CASes at least on AArch64 and PPC64.

      This is excessive for statistics gathering, and "relaxed" should be jsut as good.

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