--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/hotspot/share/gc/z/zWeakRootsProcessor.cpp	2018-06-06 00:42:30.556282958 +0200
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2015, 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.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zHeap.inline.hpp"
+#include "gc/z/zOopClosures.inline.hpp"
+#include "gc/z/zStat.hpp"
+#include "gc/z/zTask.hpp"
+#include "gc/z/zThread.hpp"
+#include "runtime/jniHandles.hpp"
+
+ZWeakRootsProcessor::ZWeakRootsProcessor(ZWorkers* workers) :
+    _workers(workers) {}
+
+class ZProcessWeakRootsTask : public ZTask {
+private:
+  ZWeakRootsIterator _weak_roots;
+
+public:
+  ZProcessWeakRootsTask() :
+      ZTask("ZProcessWeakRootsTask"),
+      _weak_roots() {}
+
+  virtual void work() {
+    ZPhantomIsAliveObjectClosure is_alive;
+    ZPhantomKeepAliveOopClosure keep_alive;
+    _weak_roots.weak_oops_do(&is_alive, &keep_alive);
+  }
+};
+
+void ZWeakRootsProcessor::process_weak_roots() {
+  ZProcessWeakRootsTask task;
+  _workers->run_parallel(&task);
+}
+
+class ZProcessConcurrentWeakRootsTask : public ZTask {
+private:
+  ZConcurrentWeakRootsIterator _concurrent_weak_roots;
+
+public:
+  ZProcessConcurrentWeakRootsTask() :
+      ZTask("ZProcessConccurentWeakRootsTask"),
+      _concurrent_weak_roots() {}
+
+  virtual void work() {
+    ZPhantomCleanOopClosure cl;
+    _concurrent_weak_roots.oops_do(&cl);
+  }
+};
+
+void ZWeakRootsProcessor::process_concurrent_weak_roots() {
+  ZProcessConcurrentWeakRootsTask task;
+  _workers->run_concurrent(&task);
+}