RFR: Hole in CAS barrier when using traversal heuristics

[Zhengyu Gu]

>  > Ok, can do it. Do you happen to have a reproducer?

Not simple reproducer. I got this by running ScimarkLU benchmark, it may 
takes a few runs.

${JAVA_HOME}/bin/java -jar jmh-specjvm2016.jar ScimarkLU --jvmArgs 
"-Xmx1g -Xms1g -XX:+UseShenandoahGC -XX:+UnlockExperimentalVMOptions 
-XX:+UnlockDiagnosticVMOptions -XX:ShenandoahGCHeuristics=traversal 
-Xlog:gc+stats" -f 1


Thanks,

-Zhengyu



> 
> Roman