JDK-8073861 : Unused VM Options in JDK9 HotSpot
  • Type: Bug
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: 9
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2015-02-25
  • Updated: 2017-05-17
  • Resolved: 2015-03-04
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JDK 9
9 b56Fixed
Sub Tasks
JDK-8175175 :  
JDK-8179104 :  
Description
HotSpot JDK9 source code contains several unused VM Options which can be removed or made obsolete. All options are defined in "hotspot/src/share/vm/runtime/globals.hpp" file.

Here a list of options with comments:

1) AdaptiveSizePausePolicy - product int flag, description: "Policy for changing generation size for pause goals" 

Unused product GC flag. Can be made obsolete.

2) AdjustConcurrency - product boolean flag, description: "Call thr_setconcurrency at thread creation time to avoid LWP starvation on MP systems (for Solaris Only)" 

Become unused as part of JDK-8038473 "Remove support for old T1 libthread", Can be removed, because used for threading support on Solaris 8 which we have not supported for a long time.

3) ParallelGCRetainPLAB - diagnostic boolean flag, description: "Retain parallel allocation buffers across scavenges; it is disabled because this currently conflicts with parallel card scanning under certain conditions."

Become unused as part of JDK-8065972 "Remove support for ParNew+SerialOld and DefNew+CMS". Code enabled by this flag will be removed by JDK-8073466 "Remove buffer retaining functionality and clean up in ParGCAllocBuffer". Flag can be made obsolete.

4) PrintJVMWarnings - development boolean flag, description: "Print warnings for unimplemented JVM functions" 

Become unused as part of JDK-8057777 "Cleanup of old and unused VM interfaces". Can be removed, because it is a development flag.

Comments
Suggested release note text: The VM Options "XX:AdaptiveSizePolicy" and "XX:ParallelGCRetainPLAB" are deprecated in JDK 9 and will be removed in JDK 10. The functionality used by these options was removed from JDK 9. The VM Option "XX:AdjustConcurrency" is removed in JDK 9, because was only used for threading support on Solaris 8 which has not been supported for a long time.
05-03-2015