--- old/src/hotspot/share/services/virtualMemoryTracker.hpp	2018-02-22 15:27:20.855517557 -0500
+++ new/src/hotspot/share/services/virtualMemoryTracker.hpp	2018-02-22 15:27:20.670517870 -0500
@@ -160,9 +160,7 @@
     as_snapshot()->by_type(to)->commit_memory(size);
   }
 
-  static inline void snapshot(VirtualMemorySnapshot* s) {
-    as_snapshot()->copy_to(s);
-  }
+  static void snapshot(VirtualMemorySnapshot* s);
 
   static VirtualMemorySnapshot* as_snapshot() {
     return (VirtualMemorySnapshot*)_snapshot;
@@ -336,6 +334,9 @@
     return compare(rgn) == 0;
   }
 
+  // uncommitted thread stack bottom, above guard pages if there is any.
+  address thread_stack_uncommitted_bottom() const;
+
   bool    add_committed_region(address addr, size_t size, const NativeCallStack& stack);
   bool    remove_uncommitted_region(address addr, size_t size);
 
@@ -389,6 +390,7 @@
 // Main class called from MemTracker to track virtual memory allocations, commits and releases.
 class VirtualMemoryTracker : AllStatic {
   friend class VirtualMemoryTrackerTest;
+  friend class ThreadStackTrackingTest;
 
  public:
   static bool initialize(NMT_TrackingLevel level);
@@ -408,6 +410,9 @@
 
   static bool transition(NMT_TrackingLevel from, NMT_TrackingLevel to);
 
+  // Snapshot current thread stacks
+  static void snapshot_thread_stacks();
+
  private:
   static SortedLinkedList<ReservedMemoryRegion, compare_reserved_region_base>* _reserved_regions;
 };