--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/hotspot/share/gc/z/zThread.hpp	2018-06-08 19:46:44.187761558 +0200
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2015, 2017, 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_Z_ZTHREAD_HPP
+#define SHARE_GC_Z_ZTHREAD_HPP
+
+#include "memory/allocation.hpp"
+#include "utilities/debug.hpp"
+
+class ZThread : public AllStatic {
+  friend class ZTask;
+
+private:
+  static __thread bool      _initialized;
+  static __thread uintptr_t _id;
+  static __thread bool      _is_vm;
+  static __thread bool      _is_java;
+  static __thread bool      _is_worker;
+  static __thread uint      _worker_id;
+
+  static void initialize();
+
+  static void ensure_initialized() {
+    if (!_initialized) {
+      initialize();
+    }
+  }
+
+  static bool has_worker_id();
+  static void set_worker_id(uint worker_id);
+  static void clear_worker_id();
+
+public:
+  static const char* name();
+
+  static uintptr_t id() {
+    ensure_initialized();
+    return _id;
+  }
+
+  static bool is_vm() {
+    ensure_initialized();
+    return _is_vm;
+  }
+
+  static bool is_java() {
+    ensure_initialized();
+    return _is_java;
+  }
+
+  static bool is_worker() {
+    ensure_initialized();
+    return _is_worker;
+  }
+
+  static uint worker_id() {
+    assert(has_worker_id(), "Worker id not initialized");
+    return _worker_id;
+  }
+};
+
+#endif // SHARE_GC_Z_ZTHREAD_HPP