--- /dev/null	2020-01-14 10:13:11.907818291 +0100
+++ new/src/hotspot/share/gc/shared/objectMarker.hpp	2020-02-21 11:14:40.600203023 +0100
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_GC_SHARED_OBJECTMARKER_HPP
+#define SHARE_GC_SHARED_OBJECTMARKER_HPP
+
+#include "memory/allocation.hpp"
+#include "oops/markWord.hpp"
+#include "utilities/growableArray.hpp"
+
+// ObjectMarker is used to support JVMTI for marking objects when walking the
+// heap.
+class ObjectMarker : public CHeapObj<mtInternal> {
+protected:
+  bool _needs_reset;
+public:
+  // initialize
+  virtual bool init() = 0;
+  // clean-up
+  virtual void done() = 0;
+
+  // mark an object if not yet marked.
+  // return true if the oop is marked by this call
+  virtual bool mark(oop o) = 0;
+  // check if the object has been
+  virtual bool marked(oop o) = 0;
+
+  bool needs_reset() const      { return _needs_reset; }
+  void set_needs_reset(bool v)  { _needs_reset = v; }
+};
+
+// Default implementation
+class DefaultObjectMarker : public ObjectMarker {
+ private:
+  // saved headers
+  GrowableArray<oop>* _saved_oop_stack;
+  GrowableArray<markWord>* _saved_mark_stack;
+
+ public:
+  DefaultObjectMarker();
+  bool init();
+  void done();
+
+  bool mark(oop o);
+  bool marked(oop o);
+};
+
+#endif // SHARE_GC_SHARED_OBJECTMARKER_HPP