diff -r c887851da33d -r 97d13893ec3c src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp	Wed Nov 27 10:21:22 2019 +0100
+++ b/src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp	Tue Nov 26 10:47:46 2019 +0100
@@ -26,6 +26,7 @@
 #include "gc/shenandoah/shenandoahFreeSet.hpp"
 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 #include "gc/shenandoah/shenandoahPacer.hpp"
+#include "runtime/atomic.hpp"
 
 /*
  * In normal concurrent cycle, we have to pace the application to let GC finish.