--- old/src/hotspot/share/gc/z/zLock.hpp	2019-10-09 14:05:57.613846038 +0200
+++ new/src/hotspot/share/gc/z/zLock.hpp	2019-10-09 14:05:57.355837651 +0200
@@ -52,6 +52,13 @@
   bool is_owned() const;
 };
 
+class ZNoLock {
+public:
+  void lock();
+  bool try_lock();
+  void unlock();
+};
+
 template <typename T>
 class ZLocker : public StackObj {
 private: