--- old/src/share/vm/gc/shared/collectedHeap.hpp	2017-07-21 12:06:45.624171212 +0200
+++ new/src/share/vm/gc/shared/collectedHeap.hpp	2017-07-21 12:06:45.565172184 +0200
@@ -102,6 +102,8 @@
 
   MemRegion _reserved;
 
+  WorkGang* _safepoint_workers;
+
  protected:
   BarrierSet* _barrier_set;
   bool _is_gc_active;
@@ -612,7 +614,7 @@
   // concurrent marking) for an intermittent non-GC safepoint.
   // If this method returns NULL, SafepointSynchronize will
   // perform cleanup tasks serially in the VMThread.
-  virtual WorkGang* get_safepoint_workers() { return NULL; }
+  virtual WorkGang* get_safepoint_workers() { return _safepoint_workers; }
 
   // Non product verification and debugging.
 #ifndef PRODUCT