JDK-6329603 : CMS: +CMSClassUnloadingEnabled and +CMSPermGenSweepingEnabled by default
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 6
  • Priority: P3
  • Status: Closed
  • Resolution: Won't Fix
  • OS: generic
  • CPU: generic
  • Submitted: 2005-09-27
  • Updated: 2014-09-02
  • Resolved: 2014-09-02
Related Reports
Relates :  
Relates :  
Customers who care to reduce pause times further would turn off
class unloading as needed, knowing the needs of their applications.

We need to do refworkload/alacrity measurements to understand and
document the performance impact if any from such a switch.

CMSClassUnloadingEnabled is already default, and there is no CMSPermGenSweepingEnabled switch any more after JDK8 perm gen changes.

EVALUATION This will need more work, since enabling perm gen collection appears to adversely impact remark times by more than we had anticipated. That investigation is formally deferred to Dolphin.

SUGGESTED FIX change the default setting of these two flags in glogals.hpp.

EVALUATION Should do by b55 if possible.