JDK-8005396 : Use ParNew with only one thread instead of DefNew as default for CMS on single CPU machines
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2012-12-21
  • Updated: 2017-02-11
  • Resolved: 2013-01-04
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JDK 8 Other
8Fixed hs25Fixed
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Description
As part of 8003820 we will deprecate the DefNew + CMS combination. The default for CMS is ParNew + CMS, but on single CPU systems we select DefNew instead of ParNew.

Since we by default select a combination that we are deprecating we should change the default to the supported combination ParNew + CMS.

The performance impact of this needs to be evaluated.
Comments
Suggested release note: On Single CPU machines Hotspot now picks ParNew with one worker thread instead of DefNew as the default young collector for CMS. To use DefNew, add -XX:-UseParNewGC on the command line when using CMS. Note that this combination will work but has been deprecated and will likely be removed in a future release.
08-01-2013