--- a/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	Mon Oct 16 23:23:27 2017 -0700
+++ b/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	Tue Oct 17 08:51:55 2017 +0200
@@ -968,6 +968,8 @@
   jint initialize();
 
   virtual void stop();
+  virtual void safepoint_synchronize_begin();
+  virtual void safepoint_synchronize_end();
 
   // Return the (conservative) maximum heap alignment for any G1 heap
   static size_t conservative_max_heap_alignment();