The HotSpot verification code is rather verbose and intrusive. I propose that we add a flag that can be used to turn this output off.

An example of the verification output:
$ java -XX:+PrintGC -XX:+UnlockDiagnosticVMOptions -XX:+VerifyBeforeExit -XX:+VerifyAfterGC -XX:+VerifyBeforeGC -XX:+UseConcMarkSweepGC -XX:+ExplicitGCInvokesConcurrent -cp /localhome/tests/ HelloSystemGC
 VerifyBeforeGC:[Verifying threads heap concurrent mark-sweep generation par new generation remset syms strs zone dict cldg metaspace chunks hand C-heap code cache ]
[GC (System.gc()) 672K->260K(121600K), 0.0060920 secs]
 VerifyAfterGC:[Verifying threads heap concurrent mark-sweep generation par new generation remset syms strs zone dict cldg metaspace chunks hand C-heap code cache ]
[Verifying threads heap concurrent mark-sweep generation par new generation remset syms strs zone dict cldg metaspace chunks hand C-heap code cache ]
[GC (CMS Initial Mark) 260K(121600K), 0.0204040 secs]
[Verifying threads heap concurrent mark-sweep generation par new generation remset syms strs zone dict cldg metaspace chunks hand C-heap code cache ]
[Verifying threads heap concurrent mark-sweep generation par new generation remset syms strs zone dict cldg metaspace chunks hand C-heap code cache ]
[GC (CMS Final Remark) [Verifying CMS Marking... done] 1604K(121600K), 0.1008210 secs]
[Verifying threads heap concurrent mark-sweep generation par new generation remset syms strs zone dict cldg metaspace chunks hand C-heap code cache ]

And with the proposed flag turned on:
[GC (System.gc()) 672K->269K(121600K), 0.0050710 secs]
[GC (CMS Initial Mark) 269K(121600K), 0.0203380 secs]
[GC (CMS Final Remark) 1613K(121600K), 0.1007210 secs]