--- /dev/null	2018-11-30 10:10:44.238550338 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahStrDedupQueue.hpp	2018-11-30 10:22:56.900300081 +0100
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
+ *
+ * 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_GC_SHENANDOAH_SHENANDOAHSTRINGDEDUPQUEUE_HPP
+#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHSTRINGDEDUPQUEUE_HPP
+
+#include "gc/shared/stringdedup/stringDedup.hpp"
+#include "gc/shenandoah/shenandoahHeap.hpp"
+#include "oops/oop.hpp"
+
+template <uint buffer_size>
+class ShenandoahOopBuffer : public CHeapObj<mtGC> {
+private:
+  oop   _buf[buffer_size];
+  uint  _index;
+  ShenandoahOopBuffer<buffer_size>* _next;
+
+public:
+  ShenandoahOopBuffer();
+
+  bool is_full()  const;
+  bool is_empty() const;
+  uint size()     const;
+
+  void push(oop obj);
+  oop pop();
+
+  void reset();
+
+  void set_next(ShenandoahOopBuffer<buffer_size>* next);
+  ShenandoahOopBuffer<buffer_size>* next() const;
+
+  void unlink_or_oops_do(StringDedupUnlinkOrOopsDoClosure* cl);
+  void oops_do(OopClosure* cl);
+};
+
+typedef ShenandoahOopBuffer<64> ShenandoahQueueBuffer;
+
+// Muti-producer and single consumer queue set
+class ShenandoahStrDedupQueue : public StringDedupQueue {
+private:
+  ShenandoahQueueBuffer** _producer_queues;
+  ShenandoahQueueBuffer*  _consumer_queue;
+  size_t                  _num_producer_queue;
+
+  // The queue is used for producers to publish completed buffers
+  ShenandoahQueueBuffer* _published_queues;
+
+  // Cached free buffers
+  ShenandoahQueueBuffer* _free_list;
+  size_t                 _num_free_buffer;
+  const size_t           _max_free_buffer;
+
+  bool                   _cancel;
+
+  // statistics
+  size_t                 _total_buffers;
+
+private:
+  ~ShenandoahStrDedupQueue();
+
+public:
+  ShenandoahStrDedupQueue();
+
+  void wait_impl();
+  void cancel_wait_impl();
+
+  void push_impl(uint worker_id, oop string_oop);
+  oop  pop_impl();
+
+  void unlink_or_oops_do_impl(StringDedupUnlinkOrOopsDoClosure* cl, size_t queue);
+
+  void print_statistics_impl();
+  void verify_impl();
+
+protected:
+  size_t num_queues() const { return (_num_producer_queue + 2); }
+
+private:
+  ShenandoahQueueBuffer* new_buffer();
+
+  void release_buffers(ShenandoahQueueBuffer* list);
+
+  ShenandoahQueueBuffer* queue_at(size_t queue_id) const;
+
+  bool pop_candidate(oop& obj);
+
+  void set_producer_buffer(ShenandoahQueueBuffer* buf, size_t queue_id);
+
+  void verify(ShenandoahQueueBuffer* head);
+};
+
+#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHSTRINGDEDUPQUEUE_HPP