jcmd provides great diagnostic output but many commands lack a timestamp in their output.

Take below example. Two iterations of the GC.finalizer_info command but the reader has no indication of what time these samples were taken at.

****
$ jcmd 1370326 GC.finalizer_info
1370326:
Unreachable instances waiting for finalization
#instances class name
-----------------------
      1734 CustomClass3
      1734 CustomClass4
      1733 CustomClass1
      1733 CustomClass2

$ jcmd 1370326 GC.finalizer_info
1370326:
Unreachable instances waiting for finalization
#instances class name
-----------------------
       879 CustomClass2
       878 CustomClass1
       878 CustomClass3
       878 CustomClass4

****
Same situation for anyone monitoring heap info:

****
$ jcmd 1370326 GC.heap_info
1370326:
garbage-first heap total reserved 31424512K, committed 65536K, used 31414K [0x0000000082000000, 0x0000000800000000)
 region size 16384K, 2 young (32768K), 1 survivors (16384K)
Metaspace used 5499K, committed 5632K, reserved 1114112K
 class space used 453K, committed 512K, reserved 1048576K
 
****

Adding a timestamp to the output of such commands would bring value add for those debugging JVM data.

The format might be able to take similar format to Thread.print jcmd command: i.e. yyyy-MM-dd HH:mm:ss