JDK-8371720 : G1: G1MergeHeapRootsTask::G1ClearBitmapClosure unnecessarily clears marking related data structures
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2025-11-12
  • Updated: 2025-11-17
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tbdUnresolved
Description
G1ClearBitmapClosure unnecessarily calls G1ConcurrentMark::clear_statistics() (and reset_top_at_mark_start()).

Everything this closure does is only for collection set regions, and those are explicitly excluding from all marking work, so the related data structures should not be in use anyway.

Fixing this should enable very-late initialization of concurrent marking.