JDK-8237013 : Release Note: Shenandoah self-fixing barriers
  • Type: Sub-task
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 14
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2020-01-13
  • Updated: 2020-01-13
  • Resolved: 2020-01-13
Before this improvement, Shenandoah LRB barrier performance penalty for accessing forwarded objects involved resolving through the forwarding pointer, until the Update References phase fixed the affected references. A more efficient implementation ships now, where LRB self-fixes the forwarded reference on the same code path, eliminating continuous resolves for potentially hot accesses. 

Self-fixing is implemented for C1 and C2 (JDK-8231087), interpreter (JDK-8232992) and runtime (JDK-8232010) barriers.