Deprecate jcmd GC.class_stats command line option

Summary

Deprecate the jcmd GC.class_stats command line option.

Problem

The GC.class_stats output is not helpful for customers and has excessive output causing buffer overruns. This feature was developed for internal use for analyzing size of metadata types for the metadata reduction project. There are now better ways in the JVM to find this data, for example, with -Xlog:cds in the CDS dumping phase. There are now better and less intrusive ways to implement this functionality if we wanted it for internal use.

Solution

Add a deprecation message to the command line option description, and remove in a later release.

Specification

 diff --git a/src/hotspot/share/services/diagnosticCommand.hpp b/src/hotspot/share/services/diagnosticCommand.hpp
 --- a/src/hotspot/share/services/diagnosticCommand.hpp
 +++ b/src/hotspot/share/services/diagnosticCommand.hpp
 @@ -388,7 +388,7 @@
      return "GC.class_stats";
    }
    static const char* description() {
 -    return "Provide statistics about Java class meta data.";
 +    return "(Deprecated) Provide statistics about Java class meta data.";
    }
    static const char* impact() {
      return "High: Depends on Java heap size and content.";

(And update the manpage in the closed repository)