RFR (S): 8068036: assert(is_available(index)) failed in G1 cset - Urgent!

[Thomas Schatzl]

Hi all,

  can I have reviews for this small change that fixes a lot of nightly
test failures that has been introduced by JDK-8060025?

Some verification code iterates through all regions using the region map
(array). This is disallowed since some time ago, causing assertion and
failure when trying to access a heap region index that is not available
at the moment.

This change fixes this by properly using a heap region closure instead
of the for-loop.

The problem has gone unnoticed because my testing has been mostly
focused on performance where the -Xms value has always been set to the
-Xmx value.

CR:
https://bugs.openjdk.java.net/browse/JDK-8068036
Webrev:
http://cr.openjdk.java.net/~tschatzl/8068036/webrev/
Testing:
parts of the failing nightly tests, jprt

Thanks,
  Thomas