JDK-8267933 : Opportunistically recalculate remembered sets for almost-eager reclaim candidates
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 17
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2021-05-28
  • Updated: 2021-08-30
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tbdUnresolved
Related Reports
Relates :  
JDK-8237500 - Increase the G1 eager reclaim candidate selection threshold
Description
Selection of eager reclaim candidates is based on the number of remembered set entries.

This is a fixed threshold, if the number of entries in the card remembered set is larger than that, we never try to eager reclaim that region.

Marking already rebuilds the remembered sets for those, but marking rounds can be far apart. Maybe it is useful to flush the remembered sets of a few of these near-candidates into the DCQ regularly to see whether something changed?
Comments
Another option could be to just increase the threshold, and for those remembered sets that are still too large, drop them completely and wait for the marking/remembered set rebuild because this would just impose too much work.
30-08-2021