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  1. JDK
  2. JDK-8178543

Optimize Klass::is_shared()

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P3
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 10
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
    • Resolved In Build:
      b21

      Description

      During itable/vtable initialization, klass->is_shared() is called frequently. Because there's no specialized implementation of Klass::is_shared(), we end up calling MetaspaceObj::is_shared, which walks the list of shared regions.

      JDK-8178351 proposes simplifying MetaspaceObj::is_shared() by doing fewer comparisons. However, in the case of Klass, we can actually use a free bit in Klass::_access_flags to indicate whether the Klass is shared, so we can have an even more optimal implementation of Klass::is_shared().

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              Assignee:
              iklam Ioi Lam
              Reporter:
              iklam Ioi Lam
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