RFR(L) 8153224 Monitor deflation prolong safepoints

[Daniel D. Daugherty]

Greetings,

Welcome to the OpenJDK review thread for my port of Carsten's work on:

     JDK-8153224 Monitor deflation prolong safepoints
     https://bugs.openjdk.java.net/browse/JDK-8153224

Here's a link to the OpenJDK wiki that describes my port:

https://wiki.openjdk.java.net/display/HotSpot/Async+Monitor+Deflation

Here's the webrev URL:

http://cr.openjdk.java.net/~dcubed/8153224-webrev/3-for-jdk13/

Here's a link to Carsten's original webrev:

http://cr.openjdk.java.net/~cvarming/monitor_deflate_conc/0/

Earlier versions of this patch have been through several rounds of
preliminary review. Many thanks to Carsten, Coleen, Robbin, and
Roman for their preliminary code review comments. A very special
thanks to Robbin and Roman for building and testing the patch in
their own environments (including specJBB2015).

This version of the patch has been thru Mach5 tier[1-8] testing on
Oracle's usual set of platforms. Earlier versions have been run
through my stress kit on my Linux-X64 and Solaris-X64 servers
(product, fastdebug, slowdebug).Earlier versions have run Kitchensink
for 12 hours on MacOSX, Linux-X64 and Solaris-X64 (product, fastdebug
and slowdebug). Earlier versions have run my monitor inflation stress
tests for 12 hours on MacOSX, Linux-X64 and Solaris-X64 (product,
fastdebug and slowdebug).

All of the testing done on earlier versions will be redone on the
latest version of the patch.

Thanks, in advance, for any questions, comments or suggestions.

Dan

P.S.
One subtest in gc/g1/humongousObjects/TestHumongousClassLoader.java
is currently failing in -Xcomp mode on Win* only. I've been trying
to characterize/analyze this failure for more than a week now. At
this point I'm convinced that Async Monitor Deflation is aggravating
an existing bug. However, I plan to have a better handle on that
failure before these bits are pushed to the jdk/jdk repo.