hg: jdk/sandbox: 8235905: ZGC: Rework how ZRootsIterator visits threads

[chris.hegarty at oracle.com]

Changeset: ff7cd49f2aef
Author:    pliden
Date:      2019-12-17 11:37 +0100
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/ff7cd49f2aef

8235905: ZGC: Rework how ZRootsIterator visits threads
Reviewed-by: stefank

! src/hotspot/share/gc/z/zRootsIterator.cpp
! src/hotspot/share/gc/z/zRootsIterator.hpp
! src/hotspot/share/runtime/threadSMR.hpp