--- a/src/hotspot/share/gc/g1/g1FullCollector.hpp	Wed Apr 18 21:10:09 2018 -0700
+++ b/src/hotspot/share/gc/g1/g1FullCollector.hpp	Thu Apr 19 09:15:17 2018 +0200
@@ -56,6 +56,8 @@
   G1IsAliveClosure          _is_alive;
   ReferenceProcessorIsAliveMutator _is_alive_mutator;
 
+  static uint calc_active_workers();
+
 public:
   G1FullCollector(G1CollectedHeap* heap, GCMemoryManager* memory_manager, bool explicit_gc, bool clear_soft_refs);
   ~G1FullCollector();