--- old/src/hotspot/share/runtime/mutexLocker.hpp	2018-03-19 14:01:15.365607497 -0700
+++ new/src/hotspot/share/runtime/mutexLocker.hpp	2018-03-19 14:01:15.081608422 -0700
@@ -125,6 +125,7 @@
 extern Monitor* Service_lock;                    // a lock used for service thread operation
 extern Monitor* PeriodicTask_lock;               // protects the periodic task structure
 extern Monitor* RedefineClasses_lock;            // locks classes from parallel redefinition
+extern Monitor* ThreadHeapSampler_lock;          // protects the static data for initialization.
 
 #if INCLUDE_TRACE
 extern Mutex*   JfrStacktrace_lock;              // used to guard access to the JFR stacktrace table