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  1. JDK
  2. JDK-8196883

G1RemSet::refine_card_concurrently doesn't need to check for cards in collection set

    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 10, 11
    • Fix Version/s: 11
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc
    • Resolved In Build:
      b01
    • CPU:
      generic
    • OS:
      generic

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        Description

        G1RemSet::refine_card_concurrently tests whether the region is in the collection set, skipping refinement if so, with an explanation that objects in the cset are about to move. But the cset is a collection pause artifact, and is clear when not in a GC pause. The test was useful when there was a single refine_card function that was used both concurrently and during a GC pause, but JDK-8177707 split the two cases into separate functions. It is no longer useful, and should be removed.

        The hot card cache handling also has a comment mentioning that it doesn't need to check the cset, since hcc is only used during concurrent processing. That comment isn't needed anymore either.

        Note that refine_card_during_gc already implicitly performs an in_cset check via the scan_top check. scan_top is initialized in part based on the collection set.

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                • Assignee:
                  tschatzl Thomas Schatzl
                  Reporter:
                  kbarrett Kim Barrett
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                  • Created:
                    Updated:
                    Resolved: