--- a/src/hotspot/share/runtime/mutexLocker.hpp	Fri Nov 03 17:09:25 2017 -0700
+++ b/src/hotspot/share/runtime/mutexLocker.hpp	Sun Nov 05 03:43:15 2017 +0100
@@ -128,7 +128,6 @@
 extern Monitor* JfrMsg_lock;                     // protects JFR messaging
 extern Mutex*   JfrBuffer_lock;                  // protects JFR buffer operations
 extern Mutex*   JfrStream_lock;                  // protects JFR stream access
-extern Mutex*   JfrThreadGroups_lock;            // protects JFR access to Thread Groups
 #endif
 
 #ifndef SUPPORTS_NATIVE_CX8