hg: shenandoah/jdk: String dedup thread's poll() can interfere with scanning at safepoint

[zgu at redhat.com]

Changeset: d3dcc4565dcb
Author:    zgu
Date:      2018-02-23 10:19 -0500
URL:       http://hg.openjdk.java.net/shenandoah/jdk/rev/d3dcc4565dcb

String dedup thread's poll() can interfere with scanning at safepoint

! src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.cpp
! src/hotspot/share/gc/shenandoah/shenandoahStrDedupQueue.cpp
! src/hotspot/share/gc/shenandoah/shenandoahStrDedupQueue.hpp
! src/hotspot/share/gc/shenandoah/shenandoahStrDedupQueue.inline.hpp
! src/hotspot/share/gc/shenandoah/shenandoahStrDedupTable.cpp
! src/hotspot/share/gc/shenandoah/shenandoahStrDedupTable.hpp
! src/hotspot/share/gc/shenandoah/shenandoahStrDedupThread.cpp
! src/hotspot/share/gc/shenandoah/shenandoahStrDedupThread.hpp
! src/hotspot/share/gc/shenandoah/shenandoahStringDedup.cpp
! src/hotspot/share/gc/shenandoah/shenandoahStringDedup.hpp