JDK-8048179 : Early reclaim of large objects that are referenced by a few objects
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 9
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2014-06-26
  • Updated: 2016-10-03
  • Resolved: 2015-01-07
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Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
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JDK 8 JDK 9
8u60Fixed 9 b47Fixed
Related Reports
Relates :  
JDK-8069034 - gc/g1/TestEagerReclaimHumongousRegionsClearMarkBits.java nightly failure
Relates :  
JDK-8058801 - G1TraceReclaimDeadHumongousObjectsAtYoungGC only prints humongous object liveness output when there is at least one candidate humongous object
Relates :  
JDK-8027959 - Early reclamation of large objects in G1
Relates :  
JDK-8069367 - Eagerly reclaimed humongous objects left on mark stack
Sub Tasks
JDK-8166785 :  
Release Note: G1 now collects unreachable Humongous objects during young collections - Closed
Description
JDK-8027959 introduces early reclamation of large objects that have no incoming references at all.

Investigate relaxing this restriction (both effectiveness/time taken) by allowing reclamation of large objects with a few references (e.g. having only sparse table entries) - just iterate over them, and reclaim if we find out there are actually no references to it.

Most likely this results in additional objects to be reclaimed, as the remembered set entries may be stale already.