JDK-8372411 : Regressions in systemgc.NoObjects and AllDead due JEP-516
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 26
  • Priority: P4
  • Status: Closed
  • Resolution: Not an Issue
  • OS: generic
  • CPU: generic
  • Submitted: 2025-11-24
  • Updated: 2025-11-24
  • Resolved: 2025-11-24
Related Reports
Relates :  
JDK-8365932 - Implementation of JEP 516: Ahead-of-Time Object Caching with Any GC
Description
JEP 516 allows enabling archived objects from CDS in non-G1 GC. When this is enabled, for example when running with ZGC, we see significant (up to 34%) regressions in microbenchmarks testing System.gc() on mostly empty heaps:
 
org.openjdk.bench.vm.gc.systemgc.NoObjects 
org.openjdk.bench.vm.gc.systemgc.AllDead
Comments
We have no reason to believe this is a real issue, rather an artifact of a minimal "empty" heap being slightly less empty when running with CDS and JEP 516 streaming enabled. We file this regression to call this out in our trends and document this as a non-issue.
24-11-2025