RFR: 8170388: Deprecate the flag -XX:ExplicitGCInvokesConcurrentAndUnloadsClasses

[Erik Helin]

Hi all,

when working on "8170067: 
-XX:ExplicitGCInvokesConcurrentAndUnloadsClasses is not implemented for 
G1" I realized that it is just a pain to support this flag now that 
-XX:CMSClassUnloadingEnabled is true by default (since JDK 8). The flag 
-XX:ExplicitGCInvokesConcurrentAndUnloadsClasses is (since JDK 8) 
completely redundant, specifying -XX:+ExplicitGCInvokesConcurrent will 
result in the exact same behavior by default (since 
CMSClassUnloadingMaxInterval is 0 by default and CMSClassUnloading is 
true by default).

Rather than supporting this flag for G1 and CMS, spending time on trying 
to validate all the strange command-line arguments combinations that can 
appear, I vote for deprecating this flag.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8170388

Patch:
http://cr.openjdk.java.net/~ehelin/8170388/00/

Testing:
- JRPT
- Added new jtreg test

A CCC request has been submitted, reviewed and approved.

Thanks,
Erik