--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Wed Sep 09 10:34:22 2015 +0200
@@ -4164,8 +4164,9 @@
         // Initialize the GC alloc regions.
         _allocator->init_gc_alloc_regions(evacuation_info);
 
+        G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers());
         // Actually do the work...
-        evacuate_collection_set(evacuation_info);
+        evacuate_collection_set(evacuation_info, &per_thread_states);
 
         free_collection_set(g1_policy()->collection_set(), evacuation_info);
 
@@ -4545,15 +4546,15 @@
 
 class G1ParTask : public AbstractGangTask {
 protected:
-  G1CollectedHeap*       _g1h;
-  G1ParScanThreadState** _pss;
-  RefToScanQueueSet*     _queues;
-  G1RootProcessor*       _root_processor;
-  ParallelTaskTerminator _terminator;
-  uint _n_workers;
+  G1CollectedHeap*         _g1h;
+  G1ParScanThreadStateSet* _pss;
+  RefToScanQueueSet*       _queues;
+  G1RootProcessor*         _root_processor;
+  ParallelTaskTerminator   _terminator;
+  uint                     _n_workers;
 
 public:
-  G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadState** per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
+  G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
     : AbstractGangTask("G1 collection"),
       _g1h(g1h),
       _pss(per_thread_states),
@@ -4611,7 +4612,7 @@
 
       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
 
-      G1ParScanThreadState*           pss = _pss[worker_id];
+      G1ParScanThreadState*           pss = _pss->state_for_worker(worker_id);
       pss->set_ref_processor(rp);
 
       bool only_young = _g1h->collector_state()->gcs_are_young();
@@ -5267,15 +5268,15 @@
 
 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
 private:
-  G1CollectedHeap*        _g1h;
-  G1ParScanThreadState**  _pss;
-  RefToScanQueueSet*      _queues;
-  WorkGang*               _workers;
-  uint                    _active_workers;
+  G1CollectedHeap*          _g1h;
+  G1ParScanThreadStateSet*  _pss;
+  RefToScanQueueSet*        _queues;
+  WorkGang*                 _workers;
+  uint                      _active_workers;
 
 public:
   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
-                           G1ParScanThreadState** per_thread_states,
+                           G1ParScanThreadStateSet* per_thread_states,
                            WorkGang* workers,
                            RefToScanQueueSet *task_queues,
                            uint n_workers) :
@@ -5299,14 +5300,14 @@
   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
   ProcessTask&     _proc_task;
   G1CollectedHeap* _g1h;
-  G1ParScanThreadState** _pss;
+  G1ParScanThreadStateSet* _pss;
   RefToScanQueueSet* _task_queues;
   ParallelTaskTerminator* _terminator;
 
 public:
   G1STWRefProcTaskProxy(ProcessTask& proc_task,
                         G1CollectedHeap* g1h,
-                        G1ParScanThreadState** per_thread_states,
+                        G1ParScanThreadStateSet* per_thread_states,
                         RefToScanQueueSet *task_queues,
                         ParallelTaskTerminator* terminator) :
     AbstractGangTask("Process reference objects in parallel"),
@@ -5324,7 +5325,7 @@
 
     G1STWIsAliveClosure is_alive(_g1h);
 
-    G1ParScanThreadState*           pss = _pss[worker_id];
+    G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
     pss->set_ref_processor(NULL);
 
     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, pss);
@@ -5403,14 +5404,14 @@
 
 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
 protected:
-  G1CollectedHeap*       _g1h;
-  G1ParScanThreadState** _pss;
-  RefToScanQueueSet*     _queues;
-  ParallelTaskTerminator _terminator;
-  uint _n_workers;
+  G1CollectedHeap*         _g1h;
+  G1ParScanThreadStateSet* _pss;
+  RefToScanQueueSet*       _queues;
+  ParallelTaskTerminator   _terminator;
+  uint                     _n_workers;
 
 public:
-  G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadState** per_thread_states, int workers, RefToScanQueueSet *task_queues) :
+  G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
     AbstractGangTask("ParPreserveCMReferents"),
     _g1h(g1h),
     _pss(per_thread_states),
@@ -5423,7 +5424,7 @@
     ResourceMark rm;
     HandleMark   hm;
 
-    G1ParScanThreadState*          pss = _pss[worker_id];
+    G1ParScanThreadState*          pss = _pss->state_for_worker(worker_id);
     pss->set_ref_processor(NULL);
     assert(pss->queue_is_empty(), "both queue and overflow should be empty");
 
@@ -5484,7 +5485,7 @@
 };
 
 // Weak Reference processing during an evacuation pause (part 1).
-void G1CollectedHeap::process_discovered_references(G1ParScanThreadState** per_thread_states) {
+void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
   double ref_proc_start = os::elapsedTime();
 
   ReferenceProcessor* rp = _ref_processor_stw;
@@ -5529,7 +5530,7 @@
   // JNI refs.
 
   // Use only a single queue for this PSS.
-  G1ParScanThreadState*           pss = per_thread_states[0];
+  G1ParScanThreadState*          pss = per_thread_states->state_for_worker(0);
   pss->set_ref_processor(NULL);
   assert(pss->queue_is_empty(), "pre-condition");
 
@@ -5590,7 +5591,7 @@
 }
 
 // Weak Reference processing during an evacuation pause (part 2).
-void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadState** per_thread_states) {
+void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
   double ref_enq_start = os::elapsedTime();
 
   ReferenceProcessor* rp = _ref_processor_stw;
@@ -5625,7 +5626,7 @@
   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
 }
 
-void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
+void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
   _expand_heap_after_alloc_failure = true;
   _evacuation_failed = false;
 
@@ -5645,11 +5646,6 @@
   double start_par_time_sec = os::elapsedTime();
   double end_par_time_sec;
 
-  G1ParScanThreadState** per_thread_states = NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC);
-  for (uint i = 0; i < n_workers; i++) {
-    per_thread_states[i] = new_par_scan_state(i);
-  }
-
   {
     G1RootProcessor root_processor(this, n_workers);
     G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
@@ -5703,11 +5699,7 @@
   _allocator->release_gc_alloc_regions(evacuation_info);
   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
 
-  for (uint i = 0; i < n_workers; i++) {
-    G1ParScanThreadState* pss = per_thread_states[i];
-    delete pss;
-  }
-  FREE_C_HEAP_ARRAY(G1ParScanThreadState*, per_thread_states);
+  per_thread_states->flush();
 
   record_obj_copy_mem_stats();
 

--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Wed Sep 09 10:34:22 2015 +0200
@@ -56,6 +56,7 @@
 class GenerationSpec;
 class OopsInHeapRegionClosure;
 class G1ParScanThreadState;
+class G1ParScanThreadStateSet;
 class G1KlassScanClosure;
 class G1ParScanThreadState;
 class ObjectClosure;
@@ -192,6 +193,7 @@
 
   // Closures used in implementation.
   friend class G1ParScanThreadState;
+  friend class G1ParScanThreadStateSet;
   friend class G1ParTask;
   friend class G1PLABAllocator;
   friend class G1PrepareCompactClosure;
@@ -584,11 +586,11 @@
 
   // Process any reference objects discovered during
   // an incremental evacuation pause.
-  void process_discovered_references(G1ParScanThreadState** per_thread_states);
+  void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 
   // Enqueue any remaining discovered references
   // after processing.
-  void enqueue_discovered_references(G1ParScanThreadState** per_thread_states);
+  void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 
 public:
   WorkGang* workers() const { return _workers; }
@@ -683,9 +685,6 @@
   // Allocates a new heap region instance.
   HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
 
-  // Allocates a new per thread par scan state for the given thread id.
-  G1ParScanThreadState* new_par_scan_state(uint worker_id);
-
   // Allocate the highest free region in the reserved heap. This will commit
   // regions as necessary.
   HeapRegion* alloc_highest_free_region();
@@ -799,7 +798,7 @@
   bool do_collection_pause_at_safepoint(double target_pause_time_ms);
 
   // Actually do the work of evacuating the collection set.
-  void evacuate_collection_set(EvacuationInfo& evacuation_info);
+  void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
 
   // Print the header for the per-thread termination statistics.
   static void print_termination_stats_hdr(outputStream* const st);

--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap_ext.cpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap_ext.cpp	Wed Sep 09 10:34:22 2015 +0200
@@ -38,7 +38,3 @@
                                              MemRegion mr) {
   return new HeapRegion(hrs_index, bot_shared(), mr);
 }
-
-G1ParScanThreadState* G1CollectedHeap::new_par_scan_state(uint worker_id) {
-  return new G1ParScanThreadState(this, worker_id);
-}

--- a/hotspot/src/share/vm/gc/g1/g1CollectorPolicy.hpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1CollectorPolicy.hpp	Wed Sep 09 10:34:22 2015 +0200
@@ -865,8 +865,8 @@
     return _recorded_survivor_regions;
   }
 
-  void record_thread_age_table(ageTable* age_table) {
-    _survivors_age_table.merge_par(age_table);
+  void record_age_table(ageTable* age_table) {
+    _survivors_age_table.merge(age_table);
   }
 
   void update_max_gc_locker_expansion();

--- a/hotspot/src/share/vm/gc/g1/g1ParScanThreadState.cpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1ParScanThreadState.cpp	Wed Sep 09 10:34:22 2015 +0200
@@ -71,11 +71,16 @@
   _dest[InCSetState::Old]          = InCSetState::Old;
 }
 
-G1ParScanThreadState::~G1ParScanThreadState() {
+// Pass locally gathered statistics to global state.
+void G1ParScanThreadState::flush() {
+  _dcq.flush();
   // Update allocation statistics.
   _plab_allocator->flush_and_retire_stats();
+  _g1h->g1_policy()->record_age_table(&_age_table);
+}
+
+G1ParScanThreadState::~G1ParScanThreadState() {
   delete _plab_allocator;
-  _g1h->g1_policy()->record_thread_age_table(&_age_table);
   // Update heap statistics.
   _g1h->update_surviving_young_words(_surviving_young_words);
   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
@@ -314,6 +319,25 @@
   }
 }
 
+G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
+  assert(worker_id < _n_workers, "out of bounds access");
+  return _states[worker_id];
+}
+
+void G1ParScanThreadStateSet::flush() {
+  assert(!_flushed, "thread local state from the per thread states should be flushed once");
+
+  for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
+    G1ParScanThreadState* pss = _states[worker_index];
+
+    pss->flush();
+
+    delete pss;
+    _states[worker_index] = NULL;
+  }
+  _flushed = true;
+}
+
 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
   assert(_g1h->obj_in_cs(old),
          err_msg("Object " PTR_FORMAT " should be in the CSet", p2i(old)));

--- a/hotspot/src/share/vm/gc/g1/g1ParScanThreadState.hpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/g1/g1ParScanThreadState.hpp	Wed Sep 09 10:34:22 2015 +0200
@@ -121,6 +121,8 @@
     return _surviving_young_words + 1;
   }
 
+  void flush();
+
  private:
   #define G1_PARTIAL_ARRAY_MASK 0x2
 
@@ -189,4 +191,34 @@
   oop handle_evacuation_failure_par(oop obj, markOop m);
 };
 
+class G1ParScanThreadStateSet : public StackObj {
+  G1CollectedHeap* _g1h;
+  G1ParScanThreadState** _states;
+  uint _n_workers;
+  bool _flushed;
+
+ public:
+  G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers) :
+      _g1h(g1h),
+      _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
+      _n_workers(n_workers),
+      _flushed(false) {
+    for (uint i = 0; i < n_workers; ++i) {
+      _states[i] = new_par_scan_state(i);
+    }
+  }
+
+  ~G1ParScanThreadStateSet() {
+    assert(_flushed, "thread local state from the per thread states should have been flushed");
+    FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
+  }
+
+  void flush();
+
+  G1ParScanThreadState* state_for_worker(uint worker_id);
+
+ private:
+  G1ParScanThreadState* new_par_scan_state(uint worker_id);
+};
+
 #endif // SHARE_VM_GC_G1_G1PARSCANTHREADSTATE_HPP

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1ParScanThreadState_ext.cpp	Wed Sep 09 10:34:22 2015 +0200
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2015, 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/g1/g1ParScanThreadState.hpp"
+
+G1ParScanThreadState* G1ParScanThreadStateSet::new_par_scan_state(uint worker_id) {
+  return new G1ParScanThreadState(_g1h, worker_id);
+}

--- a/hotspot/src/share/vm/gc/shared/ageTable.cpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/shared/ageTable.cpp	Wed Sep 09 10:34:22 2015 +0200
@@ -28,7 +28,6 @@
 #include "gc/shared/collectorPolicy.hpp"
 #include "gc/shared/gcPolicyCounters.hpp"
 #include "memory/resourceArea.hpp"
-#include "runtime/atomic.inline.hpp"
 #include "utilities/copy.hpp"
 
 /* Copyright (c) 1992, 2015, Oracle and/or its affiliates, and Stanford University.
@@ -73,12 +72,6 @@
   }
 }
 
-void ageTable::merge_par(ageTable* subTable) {
-  for (int i = 0; i < table_size; i++) {
-    Atomic::add_ptr(subTable->sizes[i], &sizes[i]);
-  }
-}
-
 uint ageTable::compute_tenuring_threshold(size_t survivor_capacity, GCPolicyCounters* gc_counters) {
   size_t desired_survivor_size = (size_t)((((double) survivor_capacity)*TargetSurvivorRatio)/100);
   uint result;

--- a/hotspot/src/share/vm/gc/shared/ageTable.hpp	Tue Sep 08 16:00:34 2015 -0400
+++ b/hotspot/src/share/vm/gc/shared/ageTable.hpp	Wed Sep 09 10:34:22 2015 +0200
@@ -68,7 +68,6 @@
   // Merge another age table with the current one.  Used
   // for parallel young generation gc.
   void merge(ageTable* subTable);
-  void merge_par(ageTable* subTable);
 
   // calculate new tenuring threshold based on age information
   uint compute_tenuring_threshold(size_t survivor_capacity, GCPolicyCounters* gc_counters);