--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ObjectHeap.java	2018-11-28 19:11:45.908696228 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/oops/ObjectHeap.java	2018-11-28 19:11:45.751697383 +0100
@@ -246,15 +246,13 @@
       }
     }
 
-    int cell_header_size = heap.cell_header_size();
-
     for (int i = 0; i < liveRegions.size(); i += 2) {
       Address bottom = (Address) liveRegions.get(i);
       Address top    = (Address) liveRegions.get(i+1);
 
       try {
         // Traverses the space from bottom to top
-        OopHandle handle = bottom.addOffsetToAsOopHandle(cell_header_size);
+        OopHandle handle = bottom.addOffsetToAsOopHandle(0);
 
         while (handle.lessThan(top)) {
         Oop obj = null;
@@ -291,7 +289,7 @@
           if ( (cmsSpaceOld != null) && cmsSpaceOld.contains(handle)) {
               handle = handle.addOffsetToAsOopHandle(CompactibleFreeListSpace.adjustObjectSizeInBytes(obj.getObjectSize()) );
           } else {
-              handle = handle.addOffsetToAsOopHandle(obj.getObjectSize() + cell_header_size);
+              handle = handle.addOffsetToAsOopHandle(obj.getObjectSize());
           }
         }
       }
@@ -371,8 +369,9 @@
         G1CollectedHeap g1h = (G1CollectedHeap) heap;
         g1h.heapRegionIterate(lrc);
     } else if (heap instanceof ShenandoahHeap) {
-        ShenandoahHeap sh = (ShenandoahHeap) heap;
-        sh.heapRegionIterate(lrc);
+       // Operation (currently) not supported with Shenandoah GC. Print
+       // a warning and leave the list of live regions empty.
+       System.err.println("Warning: Operation not supported with ZGC");
     } else if (heap instanceof ZCollectedHeap) {
        // Operation (currently) not supported with ZGC. Print
        // a warning and leave the list of live regions empty.