--- a/src/hotspot/share/jfr/metadata/jfrSerializer.hpp	Thu Sep 12 11:35:02 2019 +0200
+++ b/src/hotspot/share/jfr/metadata/jfrSerializer.hpp	Sat Sep 14 13:03:44 2019 +0200
@@ -70,9 +70,9 @@
 class JfrSerializer : public CHeapObj<mtTracing> {
  public:
   virtual ~JfrSerializer() {}
+  virtual void on_rotation() {}
   static bool register_serializer(JfrTypeId id, bool permit_cache, JfrSerializer* serializer);
-  virtual void serialize(JfrCheckpointWriter& writer) {}
-  virtual void on_rotation() {}
+  virtual void serialize(JfrCheckpointWriter& writer) = 0;
 };
 
 /*