diff -r 014c8cd323af -r 4644b3155fce src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp	Mon Jul 01 16:28:17 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp	Thu Jul 04 14:28:31 2019 +0200
@@ -43,6 +43,7 @@
 class ShenandoahGCStateResetter;
 class ShenandoahHeuristics;
 class ShenandoahMarkingContext;
+class ShenandoahMode;
 class ShenandoahPhaseTimings;
 class ShenandoahHeap;
 class ShenandoahHeapRegion;
@@ -435,6 +436,7 @@
 private:
   ShenandoahControlThread*   _control_thread;
   ShenandoahCollectorPolicy* _shenandoah_policy;
+  ShenandoahMode*            _gc_mode;
   ShenandoahHeuristics*      _heuristics;
   ShenandoahFreeSet*         _free_set;
   ShenandoahConcurrentMark*  _scm;
@@ -454,7 +456,8 @@
   ShenandoahHeuristics*      heuristics()        const { return _heuristics;        }
   ShenandoahFreeSet*         free_set()          const { return _free_set;          }
   ShenandoahConcurrentMark*  concurrent_mark()         { return _scm;               }
-  ShenandoahTraversalGC*     traversal_gc()            { return _traversal_gc;      }
+  ShenandoahTraversalGC*     traversal_gc()      const { return _traversal_gc;      }
+  bool                       is_traversal_mode() const { return _traversal_gc != NULL; }
   ShenandoahPacer*           pacer()             const { return _pacer;             }
 
   ShenandoahPhaseTimings*    phase_timings()     const { return _phase_timings;     }