JDK-8267830 : Investigate G1CardSet ConcurrentHashTable sizing heuristics
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 18
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2021-05-27
  • Updated: 2021-05-28
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tbdUnresolved
Related Reports
Blocks :  
JDK-8017163 - G1: Refactor remembered sets
Description
During clearing of the card set, we currently dump the associated ConcurrentHashTable and recreate it with InitialLogTableSize.

Investigate the benefit of having a ConcurrentHashTable sizing heuristic, that is keeping the tables at some specific other size to avoid constant resizing of these.

Initial attempts at doing so showed that this is a kind of waste of space, but more investigation should be done (particular e.g. limiting keeping some particular size to young gen regions; or size them to that "good" size only before adding elements, not keeping the ConcurrentHashTable around all the time etc).