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  1. JDK
  2. JDK-8210330

Make CLD claiming allow multiple claim bits

    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 12
    • Component/s: hotspot
    • Labels:
      None
    • Subcomponent:
      gc
    • Resolved In Build:
      b16

      Description

      Today, the claim value of a CLD is logically a boolean, stored as an int. Either a CLD is claimed, or not claimed. This is used by the GC to see if oops_do can be skipped on the CLD, because its handles have already been marked.
      With ZGC supporting concurrent class unloading, it the CLD holder can be marked finalizably reachable first, and afterwards strongly reachable. This requires 2 claim bits in the CLD: one for claiming it for strongly marking the oop handles, and one for finalizably marking the oop handles.

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            • Assignee:
              eosterlund Erik Ă–sterlund
              Reporter:
              eosterlund Erik Ă–sterlund
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              • Created:
                Updated:
                Resolved: