Merge

hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp

@@ -1816,9 +1816,7 @@ void ConcurrentMark::cleanup() {
 
   // this will also free any regions totally full of garbage objects,
   // and sort the regions.
-  g1h->g1_policy()->record_concurrent_mark_cleanup_end(
+  g1h->g1_policy()->record_concurrent_mark_cleanup_end();
-                        g1_par_note_end_task.freed_bytes(),
-                        g1_par_note_end_task.max_live_bytes());
 
   // Statistics.
   double end = os::elapsedTime();

hotspot/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp

@@ -215,19 +215,19 @@ void ConcurrentMarkThread::run() {
           gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
         }
 
-        // Now do the remainder of the cleanup operation.
+        // Now do the concurrent cleanup operation.
         _cm->completeCleanup();
-        // Notify anyone who's waiting that there are no more free
-        // regions coming. We have to do this before we join the STS,
-        // otherwise we might deadlock: a GC worker could be blocked
-        // waiting for the notification whereas this thread will be
-        // blocked for the pause to finish while it's trying to join
-        // the STS, which is conditional on the GC workers finishing.
-        g1h->reset_free_regions_coming();
 
-        _sts.join();
+        // Notify anyone who's waiting that there are no more free
-        g1_policy->record_concurrent_mark_cleanup_completed();
+        // regions coming. We have to do this before we join the STS
-        _sts.leave();
+        // (in fact, we should not attempt to join the STS in the
+        // interval between finishing the cleanup pause and clearing
+        // the free_regions_coming flag) otherwise we might deadlock:
+        // a GC worker could be blocked waiting for the notification
+        // whereas this thread will be blocked for the pause to finish
+        // while it's trying to join the STS, which is conditional on
+        // the GC workers finishing.
+        g1h->reset_free_regions_coming();
 
         double cleanup_end_sec = os::elapsedTime();
         if (PrintGC) {
@@ -240,6 +240,36 @@ void ConcurrentMarkThread::run() {
       guarantee(cm()->cleanup_list_is_empty(),
                 "at this point there should be no regions on the cleanup list");
 
+      // There is a tricky race before recording that the concurrent
+      // cleanup has completed and a potential Full GC starting around
+      // the same time. We want to make sure that the Full GC calls
+      // abort() on concurrent mark after
+      // record_concurrent_mark_cleanup_completed(), since abort() is
+      // the method that will reset the concurrent mark state. If we
+      // end up calling record_concurrent_mark_cleanup_completed()
+      // after abort() then we might incorrectly undo some of the work
+      // abort() did. Checking the has_aborted() flag after joining
+      // the STS allows the correct ordering of the two methods. There
+      // are two scenarios:
+      //
+      // a) If we reach here before the Full GC, the fact that we have
+      // joined the STS means that the Full GC cannot start until we
+      // leave the STS, so record_concurrent_mark_cleanup_completed()
+      // will complete before abort() is called.
+      //
+      // b) If we reach here during the Full GC, we'll be held up from
+      // joining the STS until the Full GC is done, which means that
+      // abort() will have completed and has_aborted() will return
+      // true to prevent us from calling
+      // record_concurrent_mark_cleanup_completed() (and, in fact, it's
+      // not needed any more as the concurrent mark state has been
+      // already reset).
+      _sts.join();
+      if (!cm()->has_aborted()) {
+        g1_policy->record_concurrent_mark_cleanup_completed();
+      }
+      _sts.leave();
+
       if (cm()->has_aborted()) {
         if (PrintGC) {
           gclog_or_tty->date_stamp(PrintGCDateStamps);
@@ -248,7 +278,7 @@ void ConcurrentMarkThread::run() {
         }
       }
 
-      // we now want to allow clearing of the marking bitmap to be
+      // We now want to allow clearing of the marking bitmap to be
       // suspended by a collection pause.
       _sts.join();
       _cm->clearNextBitmap();

hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -2011,8 +2011,6 @@ jint G1CollectedHeap::initialize() {
   // Perform any initialization actions delegated to the policy.
   g1_policy()->init();
 
-  g1_policy()->note_start_of_mark_thread();
-
   _refine_cte_cl =
     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
                                     g1_rem_set(),
@@ -3960,9 +3958,6 @@ void G1CollectedHeap::remove_self_forwarding_pointers() {
         // _next_top_at_mark_start == top, _next_marked_bytes == 0
         // _next_marked_bytes == next_marked_bytes.
       }
-
-      // Now make sure the region has the right index in the sorted array.
-      g1_policy()->note_change_in_marked_bytes(cur);
     }
     cur = cur->next_in_collection_set();
   }
@@ -5073,7 +5068,7 @@ public:
 
     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
     for (int idx = i; idx < limit; idx += stride) {
-      DiscoveredList& ref_list = rp->discovered_soft_refs()[idx];
+      DiscoveredList& ref_list = rp->discovered_refs()[idx];
 
       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
       while (iter.has_next()) {

hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp

@@ -225,16 +225,12 @@ G1CollectorPolicy::G1CollectorPolicy() :
   _recent_CS_bytes_surviving(new TruncatedSeq(NumPrevPausesForHeuristics)),
 
   _recent_avg_pause_time_ratio(0.0),
-  _num_markings(0),
-  _n_marks(0),
-  _n_pauses_at_mark_end(0),
 
   _all_full_gc_times_ms(new NumberSeq()),
 
   // G1PausesBtwnConcMark defaults to -1
   // so the hack is to do the cast  QQQ FIXME
   _pauses_btwn_concurrent_mark((size_t)G1PausesBtwnConcMark),
-  _n_marks_since_last_pause(0),
   _initiate_conc_mark_if_possible(false),
   _during_initial_mark_pause(false),
   _should_revert_to_full_young_gcs(false),
@@ -440,6 +436,7 @@ G1CollectorPolicy::G1CollectorPolicy() :
   _reserve_regions = 0;
 
   initialize_all();
+  _collectionSetChooser = new CollectionSetChooser();
 }
 
 // Increment "i", mod "len"
@@ -921,6 +918,7 @@ void G1CollectorPolicy::record_full_collection_end() {
   // Reset survivors SurvRateGroup.
   _survivor_surv_rate_group->reset();
   update_young_list_target_length();
+  _collectionSetChooser->updateAfterFullCollection();
 }
 
 void G1CollectorPolicy::record_stop_world_start() {
@@ -1029,39 +1027,7 @@ void G1CollectorPolicy::record_concurrent_mark_cleanup_start() {
   _mark_cleanup_start_sec = os::elapsedTime();
 }
 
-void
+void G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
-G1CollectorPolicy::record_concurrent_mark_cleanup_end(size_t freed_bytes,
-                                                      size_t max_live_bytes) {
-  record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
-  record_concurrent_mark_cleanup_end_work2();
-}
-
-void
-G1CollectorPolicy::
-record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
-                                         size_t max_live_bytes) {
-  if (_n_marks < 2) {
-    _n_marks++;
-  }
-}
-
-// The important thing about this is that it includes "os::elapsedTime".
-void G1CollectorPolicy::record_concurrent_mark_cleanup_end_work2() {
-  double end_time_sec = os::elapsedTime();
-  double elapsed_time_ms = (end_time_sec - _mark_cleanup_start_sec)*1000.0;
-  _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
-  _cur_mark_stop_world_time_ms += elapsed_time_ms;
-  _prev_collection_pause_end_ms += elapsed_time_ms;
-
-  _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_time_sec, true);
-
-  _num_markings++;
-  _n_pauses_at_mark_end = _n_pauses;
-  _n_marks_since_last_pause++;
-}
-
-void
-G1CollectorPolicy::record_concurrent_mark_cleanup_completed() {
   _should_revert_to_full_young_gcs = false;
   _last_full_young_gc = true;
   _in_marking_window = false;
@@ -1501,11 +1467,9 @@ void G1CollectorPolicy::record_collection_pause_end() {
     summary->record_other_time_ms(other_time_ms);
   }
   for (int i = 0; i < _aux_num; ++i)
-    if (_cur_aux_times_set[i])
+    if (_cur_aux_times_set[i]) {
       _all_aux_times_ms[i].add(_cur_aux_times_ms[i]);
-
+    }
-  // Reset marks-between-pauses counter.
-  _n_marks_since_last_pause = 0;
 
   // Update the efficiency-since-mark vars.
   double proc_ms = elapsed_ms * (double) _parallel_gc_threads;
@@ -1729,6 +1693,8 @@ void G1CollectorPolicy::record_collection_pause_end() {
   double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
   adjust_concurrent_refinement(update_rs_time, update_rs_processed_buffers, update_rs_time_goal_ms);
   // </NEW PREDICTION>
+
+  assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
 }
 
 #define EXT_SIZE_FORMAT "%d%s"
@@ -2156,10 +2122,6 @@ size_t G1CollectorPolicy::expansion_amount() {
   }
 }
 
-void G1CollectorPolicy::note_start_of_mark_thread() {
-  _mark_thread_startup_sec = os::elapsedTime();
-}
-
 class CountCSClosure: public HeapRegionClosure {
   G1CollectorPolicy* _g1_policy;
 public:
@@ -2446,7 +2408,7 @@ public:
   }
 };
 
-bool G1CollectorPolicy_BestRegionsFirst::assertMarkedBytesDataOK() {
+bool G1CollectorPolicy::assertMarkedBytesDataOK() {
   HRSortIndexIsOKClosure cl(_collectionSetChooser);
   _g1->heap_region_iterate(&cl);
   return true;
@@ -2532,12 +2494,6 @@ G1CollectorPolicy::decide_on_conc_mark_initiation() {
   }
 }
 
-void
-G1CollectorPolicy_BestRegionsFirst::
-record_collection_pause_start(double start_time_sec, size_t start_used) {
-  G1CollectorPolicy::record_collection_pause_start(start_time_sec, start_used);
-}
-
 class KnownGarbageClosure: public HeapRegionClosure {
   CollectionSetChooser* _hrSorted;
 
@@ -2645,20 +2601,20 @@ public:
 };
 
 void
-G1CollectorPolicy_BestRegionsFirst::
+G1CollectorPolicy::record_concurrent_mark_cleanup_end() {
-record_concurrent_mark_cleanup_end(size_t freed_bytes,
+  double start_sec;
-                                   size_t max_live_bytes) {
+  if (G1PrintParCleanupStats) {
-  double start;
+    start_sec = os::elapsedTime();
-  if (G1PrintParCleanupStats) start = os::elapsedTime();
+  }
-  record_concurrent_mark_cleanup_end_work1(freed_bytes, max_live_bytes);
 
   _collectionSetChooser->clearMarkedHeapRegions();
-  double clear_marked_end;
+  double clear_marked_end_sec;
   if (G1PrintParCleanupStats) {
-    clear_marked_end = os::elapsedTime();
+    clear_marked_end_sec = os::elapsedTime();
-    gclog_or_tty->print_cr("  clear marked regions + work1: %8.3f ms.",
+    gclog_or_tty->print_cr("  clear marked regions: %8.3f ms.",
-                  (clear_marked_end - start)*1000.0);
+                           (clear_marked_end_sec - start_sec) * 1000.0);
   }
+
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     const size_t OverpartitionFactor = 4;
     const size_t MinWorkUnit = 8;
@@ -2677,27 +2633,25 @@ record_concurrent_mark_cleanup_end(size_t freed_bytes,
     KnownGarbageClosure knownGarbagecl(_collectionSetChooser);
     _g1->heap_region_iterate(&knownGarbagecl);
   }
-  double known_garbage_end;
+  double known_garbage_end_sec;
   if (G1PrintParCleanupStats) {
-    known_garbage_end = os::elapsedTime();
+    known_garbage_end_sec = os::elapsedTime();
     gclog_or_tty->print_cr("  compute known garbage: %8.3f ms.",
-                  (known_garbage_end - clear_marked_end)*1000.0);
+                      (known_garbage_end_sec - clear_marked_end_sec) * 1000.0);
-  }
-  _collectionSetChooser->sortMarkedHeapRegions();
-  double sort_end;
-  if (G1PrintParCleanupStats) {
-    sort_end = os::elapsedTime();
-    gclog_or_tty->print_cr("  sorting: %8.3f ms.",
-                  (sort_end - known_garbage_end)*1000.0);
   }
 
-  record_concurrent_mark_cleanup_end_work2();
+  _collectionSetChooser->sortMarkedHeapRegions();
-  double work2_end;
+  double end_sec = os::elapsedTime();
   if (G1PrintParCleanupStats) {
-    work2_end = os::elapsedTime();
+    gclog_or_tty->print_cr("  sorting: %8.3f ms.",
-    gclog_or_tty->print_cr("  work2: %8.3f ms.",
+                           (end_sec - known_garbage_end_sec) * 1000.0);
-                  (work2_end - sort_end)*1000.0);
   }
+
+  double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
+  _concurrent_mark_cleanup_times_ms->add(elapsed_time_ms);
+  _cur_mark_stop_world_time_ms += elapsed_time_ms;
+  _prev_collection_pause_end_ms += elapsed_time_ms;
+  _mmu_tracker->add_pause(_mark_cleanup_start_sec, end_sec, true);
 }
 
 // Add the heap region at the head of the non-incremental collection set
@@ -2912,9 +2866,7 @@ void G1CollectorPolicy::print_collection_set(HeapRegion* list_head, outputStream
 }
 #endif // !PRODUCT
 
-void
+void G1CollectorPolicy::choose_collection_set(double target_pause_time_ms) {
-G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
-                                                  double target_pause_time_ms) {
   // Set this here - in case we're not doing young collections.
   double non_young_start_time_sec = os::elapsedTime();
 
@@ -3115,14 +3067,3 @@ G1CollectorPolicy_BestRegionsFirst::choose_collection_set(
   _recorded_non_young_cset_choice_time_ms =
     (non_young_end_time_sec - non_young_start_time_sec) * 1000.0;
 }
-
-void G1CollectorPolicy_BestRegionsFirst::record_full_collection_end() {
-  G1CollectorPolicy::record_full_collection_end();
-  _collectionSetChooser->updateAfterFullCollection();
-}
-
-void G1CollectorPolicy_BestRegionsFirst::
-record_collection_pause_end() {
-  G1CollectorPolicy::record_collection_pause_end();
-  assert(assertMarkedBytesDataOK(), "Marked regions not OK at pause end.");
-}

hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.hpp

@@ -84,7 +84,7 @@ public:
 };
 
 class G1CollectorPolicy: public CollectorPolicy {
-protected:
+private:
   // The number of pauses during the execution.
   long _n_pauses;
 
@@ -106,10 +106,7 @@ protected:
     initialize_perm_generation(PermGen::MarkSweepCompact);
   }
 
-  virtual size_t default_init_heap_size() {
+  CollectionSetChooser* _collectionSetChooser;
-    // Pick some reasonable default.
-    return 8*M;
-  }
 
   double _cur_collection_start_sec;
   size_t _cur_collection_pause_used_at_start_bytes;
@@ -316,7 +313,6 @@ private:
                                     double update_rs_processed_buffers,
                                     double goal_ms);
 
-protected:
   double _pause_time_target_ms;
   double _recorded_young_cset_choice_time_ms;
   double _recorded_non_young_cset_choice_time_ms;
@@ -554,7 +550,7 @@ public:
     return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
   }
 
-protected:
+private:
   void print_stats(int level, const char* str, double value);
   void print_stats(int level, const char* str, int value);
 
@@ -588,10 +584,6 @@ protected:
   // Statistics kept per GC stoppage, pause or full.
   TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
 
-  // We track markings.
-  int _num_markings;
-  double _mark_thread_startup_sec;       // Time at startup of marking thread
-
   // Add a new GC of the given duration and end time to the record.
   void update_recent_gc_times(double end_time_sec, double elapsed_ms);
 
@@ -664,12 +656,6 @@ protected:
   // young list/collection set).
   size_t _inc_cset_predicted_bytes_to_copy;
 
-  // Info about marking.
-  int _n_marks; // Sticky at 2, so we know when we've done at least 2.
-
-  // The number of collection pauses at the end of the last mark.
-  size_t _n_pauses_at_mark_end;
-
   // Stash a pointer to the g1 heap.
   G1CollectedHeap* _g1;
 
@@ -737,8 +723,6 @@ protected:
   // Number of pauses between concurrent marking.
   size_t _pauses_btwn_concurrent_mark;
 
-  size_t _n_marks_since_last_pause;
-
   // At the end of a pause we check the heap occupancy and we decide
   // whether we will start a marking cycle during the next pause. If
   // we decide that we want to do that, we will set this parameter to
@@ -810,6 +794,11 @@ protected:
   bool predict_will_fit(size_t young_length, double base_time_ms,
                         size_t base_free_regions, double target_pause_time_ms);
 
+  // Count the number of bytes used in the CS.
+  void count_CS_bytes_used();
+
+  void update_young_list_size_using_newratio(size_t number_of_heap_regions);
+
 public:
 
   G1CollectorPolicy();
@@ -836,22 +825,9 @@ public:
   // This should be called after the heap is resized.
   void record_new_heap_size(size_t new_number_of_regions);
 
-protected:
-
-  // Count the number of bytes used in the CS.
-  void count_CS_bytes_used();
-
-  // Together these do the base cleanup-recording work.  Subclasses might
-  // want to put something between them.
-  void record_concurrent_mark_cleanup_end_work1(size_t freed_bytes,
-                                                size_t max_live_bytes);
-  void record_concurrent_mark_cleanup_end_work2();
-
-  void update_young_list_size_using_newratio(size_t number_of_heap_regions);
-
 public:
 
-  virtual void init();
+  void init();
 
   // Create jstat counters for the policy.
   virtual void initialize_gc_policy_counters();
@@ -876,10 +852,9 @@ public:
   // start time, where the given number of bytes were used at the start.
   // This may involve changing the desired size of a collection set.
 
-  virtual void record_stop_world_start();
+  void record_stop_world_start();
 
-  virtual void record_collection_pause_start(double start_time_sec,
+  void record_collection_pause_start(double start_time_sec, size_t start_used);
-                                             size_t start_used);
 
   // Must currently be called while the world is stopped.
   void record_concurrent_mark_init_end(double
@@ -887,23 +862,22 @@ public:
 
   void record_mark_closure_time(double mark_closure_time_ms);
 
-  virtual void record_concurrent_mark_remark_start();
+  void record_concurrent_mark_remark_start();
-  virtual void record_concurrent_mark_remark_end();
+  void record_concurrent_mark_remark_end();
 
-  virtual void record_concurrent_mark_cleanup_start();
+  void record_concurrent_mark_cleanup_start();
-  virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
+  void record_concurrent_mark_cleanup_end();
-                                                  size_t max_live_bytes);
+  void record_concurrent_mark_cleanup_completed();
-  virtual void record_concurrent_mark_cleanup_completed();
 
-  virtual void record_concurrent_pause();
+  void record_concurrent_pause();
-  virtual void record_concurrent_pause_end();
+  void record_concurrent_pause_end();
 
-  virtual void record_collection_pause_end();
+  void record_collection_pause_end();
   void print_heap_transition();
 
   // Record the fact that a full collection occurred.
-  virtual void record_full_collection_start();
+  void record_full_collection_start();
-  virtual void record_full_collection_end();
+  void record_full_collection_end();
 
   void record_gc_worker_start_time(int worker_i, double ms) {
     _par_last_gc_worker_start_times_ms[worker_i] = ms;
@@ -1022,7 +996,7 @@ public:
   // Choose a new collection set.  Marks the chosen regions as being
   // "in_collection_set", and links them together.  The head and number of
   // the collection set are available via access methods.
-  virtual void choose_collection_set(double target_pause_time_ms) = 0;
+  void choose_collection_set(double target_pause_time_ms);
 
   // The head of the list (via "next_in_collection_set()") representing the
   // current collection set.
@@ -1107,19 +1081,12 @@ public:
 
   // If an expansion would be appropriate, because recent GC overhead had
   // exceeded the desired limit, return an amount to expand by.
-  virtual size_t expansion_amount();
+  size_t expansion_amount();
-
-  // note start of mark thread
-  void note_start_of_mark_thread();
-
-  // The marked bytes of the "r" has changed; reclassify it's desirability
-  // for marking.  Also asserts that "r" is eligible for a CS.
-  virtual void note_change_in_marked_bytes(HeapRegion* r) = 0;
 
 #ifndef PRODUCT
   // Check any appropriate marked bytes info, asserting false if
   // something's wrong, else returning "true".
-  virtual bool assertMarkedBytesDataOK() = 0;
+  bool assertMarkedBytesDataOK();
 #endif
 
   // Print tracing information.
@@ -1182,10 +1149,10 @@ public:
     return ret;
   }
 
+private:
   //
   // Survivor regions policy.
   //
-protected:
 
   // Current tenuring threshold, set to 0 if the collector reaches the
   // maximum amount of suvivors regions.
@@ -1265,51 +1232,6 @@ public:
 
 };
 
-// This encapsulates a particular strategy for a g1 Collector.
-//
-//      Start a concurrent mark when our heap size is n bytes
-//            greater then our heap size was at the last concurrent
-//            mark.  Where n is a function of the CMSTriggerRatio
-//            and the MinHeapFreeRatio.
-//
-//      Start a g1 collection pause when we have allocated the
-//            average number of bytes currently being freed in
-//            a collection, but only if it is at least one region
-//            full
-//
-//      Resize Heap based on desired
-//      allocation space, where desired allocation space is
-//      a function of survival rate and desired future to size.
-//
-//      Choose collection set by first picking all older regions
-//      which have a survival rate which beats our projected young
-//      survival rate.  Then fill out the number of needed regions
-//      with young regions.
-
-class G1CollectorPolicy_BestRegionsFirst: public G1CollectorPolicy {
-  CollectionSetChooser* _collectionSetChooser;
-
-  virtual void choose_collection_set(double target_pause_time_ms);
-  virtual void record_collection_pause_start(double start_time_sec,
-                                             size_t start_used);
-  virtual void record_concurrent_mark_cleanup_end(size_t freed_bytes,
-                                                  size_t max_live_bytes);
-  virtual void record_full_collection_end();
-
-public:
-  G1CollectorPolicy_BestRegionsFirst() {
-    _collectionSetChooser = new CollectionSetChooser();
-  }
-  void record_collection_pause_end();
-  // This is not needed any more, after the CSet choosing code was
-  // changed to use the pause prediction work. But let's leave the
-  // hook in just in case.
-  void note_change_in_marked_bytes(HeapRegion* r) { }
-#ifndef PRODUCT
-  bool assertMarkedBytesDataOK();
-#endif
-};
-
 // This should move to some place more general...
 
 // If we have "n" measurements, and we've kept track of their "sum" and the

hotspot/src/share/vm/memory/referenceProcessor.cpp

@@ -105,19 +105,22 @@ ReferenceProcessor::ReferenceProcessor(MemRegion span,
   _discovery_is_mt     = mt_discovery;
   _num_q               = MAX2(1, mt_processing_degree);
   _max_num_q           = MAX2(_num_q, mt_discovery_degree);
-  _discoveredSoftRefs  = NEW_C_HEAP_ARRAY(DiscoveredList,
+  _discovered_refs     = NEW_C_HEAP_ARRAY(DiscoveredList,
                                           _max_num_q * number_of_subclasses_of_ref());
-  if (_discoveredSoftRefs == NULL) {
+  if (_discovered_refs == NULL) {
     vm_exit_during_initialization("Could not allocated RefProc Array");
   }
+  _discoveredSoftRefs    = &_discovered_refs[0];
   _discoveredWeakRefs    = &_discoveredSoftRefs[_max_num_q];
   _discoveredFinalRefs   = &_discoveredWeakRefs[_max_num_q];
   _discoveredPhantomRefs = &_discoveredFinalRefs[_max_num_q];
-  // Initialized all entries to NULL
+
+  // Initialize all entries to NULL
   for (int i = 0; i < _max_num_q * number_of_subclasses_of_ref(); i++) {
-    _discoveredSoftRefs[i].set_head(NULL);
+    _discovered_refs[i].set_head(NULL);
-    _discoveredSoftRefs[i].set_length(0);
+    _discovered_refs[i].set_length(0);
   }
+
   // If we do barriers, cache a copy of the barrier set.
   if (discovered_list_needs_barrier) {
     _bs = Universe::heap()->barrier_set();
@@ -129,7 +132,7 @@ ReferenceProcessor::ReferenceProcessor(MemRegion span,
 void ReferenceProcessor::verify_no_references_recorded() {
   guarantee(!_discovering_refs, "Discovering refs?");
   for (int i = 0; i < _max_num_q * number_of_subclasses_of_ref(); i++) {
-    guarantee(_discoveredSoftRefs[i].is_empty(),
+    guarantee(_discovered_refs[i].is_empty(),
               "Found non-empty discovered list");
   }
 }
@@ -138,9 +141,9 @@ void ReferenceProcessor::verify_no_references_recorded() {
 void ReferenceProcessor::weak_oops_do(OopClosure* f) {
   for (int i = 0; i < _max_num_q * number_of_subclasses_of_ref(); i++) {
     if (UseCompressedOops) {
-      f->do_oop((narrowOop*)_discoveredSoftRefs[i].adr_head());
+      f->do_oop((narrowOop*)_discovered_refs[i].adr_head());
     } else {
-      f->do_oop((oop*)_discoveredSoftRefs[i].adr_head());
+      f->do_oop((oop*)_discovered_refs[i].adr_head());
     }
   }
 }
@@ -423,15 +426,15 @@ void ReferenceProcessor::enqueue_discovered_reflists(HeapWord* pending_list_addr
   AbstractRefProcTaskExecutor* task_executor) {
   if (_processing_is_mt && task_executor != NULL) {
     // Parallel code
-    RefProcEnqueueTask tsk(*this, _discoveredSoftRefs,
+    RefProcEnqueueTask tsk(*this, _discovered_refs,
                            pending_list_addr, _max_num_q);
     task_executor->execute(tsk);
   } else {
     // Serial code: call the parent class's implementation
     for (int i = 0; i < _max_num_q * number_of_subclasses_of_ref(); i++) {
-      enqueue_discovered_reflist(_discoveredSoftRefs[i], pending_list_addr);
+      enqueue_discovered_reflist(_discovered_refs[i], pending_list_addr);
-      _discoveredSoftRefs[i].set_head(NULL);
+      _discovered_refs[i].set_head(NULL);
-      _discoveredSoftRefs[i].set_length(0);
+      _discovered_refs[i].set_length(0);
     }
   }
 }
@@ -691,7 +694,7 @@ void ReferenceProcessor::abandon_partial_discovery() {
     if (TraceReferenceGC && PrintGCDetails && ((i % _max_num_q) == 0)) {
       gclog_or_tty->print_cr("\nAbandoning %s discovered list", list_name(i));
     }
-    abandon_partial_discovered_list(_discoveredSoftRefs[i]);
+    abandon_partial_discovered_list(_discovered_refs[i]);
   }
 }
 
@@ -952,7 +955,7 @@ void ReferenceProcessor::clean_up_discovered_references() {
         "\nScrubbing %s discovered list of Null referents",
         list_name(i));
     }
-    clean_up_discovered_reflist(_discoveredSoftRefs[i]);
+    clean_up_discovered_reflist(_discovered_refs[i]);
   }
 }
 
@@ -1402,7 +1405,7 @@ void ReferenceProcessor::verify_ok_to_handle_reflists() {
 void ReferenceProcessor::clear_discovered_references() {
   guarantee(!_discovering_refs, "Discovering refs?");
   for (int i = 0; i < _max_num_q * number_of_subclasses_of_ref(); i++) {
-    clear_discovered_references(_discoveredSoftRefs[i]);
+    clear_discovered_references(_discovered_refs[i]);
   }
 }
 

hotspot/src/share/vm/memory/referenceProcessor.hpp

@@ -255,7 +255,11 @@ class ReferenceProcessor : public CHeapObj {
   int             _num_q;
   // The maximum MT'ness degree of the queues below
   int             _max_num_q;
-  // Arrays of lists of oops, one per thread
+
+  // Master array of discovered oops
+  DiscoveredList* _discovered_refs;
+
+  // Arrays of lists of oops, one per thread (pointers into master array above)
   DiscoveredList* _discoveredSoftRefs;
   DiscoveredList* _discoveredWeakRefs;
   DiscoveredList* _discoveredFinalRefs;
@@ -267,7 +271,8 @@ class ReferenceProcessor : public CHeapObj {
   int num_q()                              { return _num_q; }
   int max_num_q()                          { return _max_num_q; }
   void set_active_mt_degree(int v)         { _num_q = v; }
-  DiscoveredList* discovered_soft_refs()   { return _discoveredSoftRefs; }
+
+  DiscoveredList* discovered_refs()        { return _discovered_refs; }
 
   ReferencePolicy* setup_policy(bool always_clear) {
     _current_soft_ref_policy = always_clear ?
@@ -411,6 +416,7 @@ class ReferenceProcessor : public CHeapObj {
   // constructor
   ReferenceProcessor():
     _span((HeapWord*)NULL, (HeapWord*)NULL),
+    _discovered_refs(NULL),
     _discoveredSoftRefs(NULL),  _discoveredWeakRefs(NULL),
     _discoveredFinalRefs(NULL), _discoveredPhantomRefs(NULL),
     _discovering_refs(false),

hotspot/src/share/vm/memory/universe.cpp

@@ -893,7 +893,7 @@ jint Universe::initialize_heap() {
 
   } else if (UseG1GC) {
 #ifndef SERIALGC
-    G1CollectorPolicy* g1p = new G1CollectorPolicy_BestRegionsFirst();
+    G1CollectorPolicy* g1p = new G1CollectorPolicy();
     G1CollectedHeap* g1h = new G1CollectedHeap(g1p);
     Universe::_collectedHeap = g1h;
 #else  // SERIALGC