JDK-7098085 : G1: partially-young GCs not initiated under certain circumstances
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs23
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2011-10-05
  • Updated: 2013-10-04
  • Resolved: 2012-01-23
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7u4Fixed 8Fixed hs23Fixed
It looks as if G1 does not always initiate partially-young GCs after a concurrent marking cycle. The flag that initiates partially-young GCs is _last_full_young_gc (it means: the next GC will be the last young GC and we'll do partially-young ones after that) and it's set in record_concurrent_mark_cleanup_completed(). This is called at the end of concurrent cleanup:

      // Check if cleanup set the free_regions_coming flag. If it
      // hasn't, we can just skip the next step.
      if (g1h->free_regions_coming()) {


Note, however, that unfortunately it's only called if free_regions_coming() is true, which is only true if cleanup found totally empty regions to reclaim.

Many thanks to Thomas Schatzl for bringing this up.


EVALUATION http://hg.openjdk.java.net/hsx/hotspot-gc/hotspot/rev/ec4b032a4977

EVALUATION See Description.