Backport is pretty straightforward from jdk9. It took longer than expected, cause I fell into Atomic::add(jlong) trap again :-( Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/8u-strdedup/webrev.00/ Test: hotspot_gc_shenandoah (fastdebug and release) Thanks, -Zhengyu