--- /dev/null	2019-02-13 16:01:02.292000000 +0300
+++ new/src/share/vm/jfr/recorder/checkpoint/types/jfrThreadGroup.hpp	2019-02-15 19:03:14.169551470 +0300
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2016, 2018, 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_VM_JFR_RECORDER_CHECKPOINT_TYPES_JFRTHREADGROUP_HPP
+#define SHARE_VM_JFR_RECORDER_CHECKPOINT_TYPES_JFRTHREADGROUP_HPP
+
+#include "jni.h"
+#include "jfr/utilities/jfrAllocation.hpp"
+#include "jfr/utilities/jfrTypes.hpp"
+
+class JfrCheckpointWriter;
+template <typename>
+class GrowableArray;
+class JfrThreadGroupsHelper;
+class JfrThreadGroupPointers;
+
+class JfrThreadGroup : public JfrCHeapObj {
+  friend class JfrCheckpointThreadClosure;
+ private:
+  static JfrThreadGroup* _instance;
+  class JfrThreadGroupEntry;
+  GrowableArray<JfrThreadGroupEntry*>* _list;
+
+  JfrThreadGroup();
+  JfrThreadGroupEntry* find_entry(const JfrThreadGroupPointers& ptrs) const;
+  JfrThreadGroupEntry* new_entry(JfrThreadGroupPointers& ptrs);
+  int add_entry(JfrThreadGroupEntry* const tge);
+
+  void write_thread_group_entries(JfrCheckpointWriter& writer) const;
+  void write_selective_thread_group(JfrCheckpointWriter* writer, traceid thread_group_id) const;
+
+  static traceid thread_group_id_internal(JfrThreadGroupsHelper& helper);
+  static JfrThreadGroup* instance();
+  static void set_instance(JfrThreadGroup* new_instance);
+
+ public:
+  ~JfrThreadGroup();
+  static void serialize(JfrCheckpointWriter& w);
+  static void serialize(JfrCheckpointWriter* w, traceid thread_group_id);
+  static traceid thread_group_id(JavaThread* thread);
+  static traceid thread_group_id(const JavaThread* thread, Thread* current);
+};
+
+#endif // SHARE_VM_JFR_RECORDER_CHECKPOINT_TYPES_JFRTHREADGROUP_HPP