Review Request (8u): 8081219: hs_err improvement: Add event logging for class redefinition to the hs_err file

[Poonam Bajaj Parhar]

Hello,

Could I request code review of the following changes backported to 8u 
for the CR 8081219 <https://bugs.openjdk.java.net/browse/JDK-8081219>:

Bug 8081219 <https://bugs.openjdk.java.net/browse/JDK-8081219>: hs_err 
improvement: Add event logging for class redefinition to the hs_err file
Webrev: http://cr.openjdk.java.net/~poonam/8081219/webrev.8u/

JDk9 patch applies cleanly to 8u repo.

Verified the changes by manually crashing the tests under 
<jdk>/java/lang/instrument/. Output like the following appears in the 
generated hs_err log file:

Classes redefined (10 events):
Event: 6.383 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=30
Event: 6.578 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=31
Event: 6.774 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=32
Event: 6.969 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=33
Event: 7.165 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=34
Event: 7.360 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=35
Event: 7.554 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=36
Event: 7.750 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=37
Event: 7.945 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=38
Event: 8.141 Thread 0x00000001002e9000 redefined class name=BigClass, 
count=39

Thanks,
Poonam