Request for review (s) - 8069004: Kitchensink hanged with 16Gb heap and GC pause >30 min

[Jon Masamitsu]

8069004: Kitchensink hanged with 16Gb heap and GC pause >30 min

The cause of 8069004 is a circularity created in a list of regions.
This failure has not been reproduced to help diagnose the problem
further.  This patch saves some information in the code that constructs the
region list to aid in diagnosing the problem when it reoccurs.

http://cr.openjdk.java.net/~jmasa/8069004/webrev.00/

Issue

https://bugs.openjdk.java.net/browse/JDK-8074576

was created to remove this debugging code in 3 months
if the problem does not reoccur.

Testing: kitchensink