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src/hotspot/share/gc/g1/g1CollectionSet.cpp

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  42 }
  43 
  44 G1GCPhaseTimes* G1CollectionSet::phase_times() {
  45   return _policy->phase_times();
  46 }
  47 
  48 double G1CollectionSet::predict_region_elapsed_time_ms(HeapRegion* hr) {
  49   return _policy->predict_region_elapsed_time_ms(hr, collector_state()->in_young_only_phase());
  50 }
  51 
  52 G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy) :
  53   _g1h(g1h),
  54   _policy(policy),
  55   _candidates(NULL),
  56   _eden_region_length(0),
  57   _survivor_region_length(0),
  58   _old_region_length(0),
  59   _collection_set_regions(NULL),
  60   _collection_set_cur_length(0),
  61   _collection_set_max_length(0),
  62   _num_optional_regions(0),


  63   _bytes_used_before(0),
  64   _recorded_rs_lengths(0),
  65   _inc_build_state(Inactive),
  66   _inc_part_start(0),
  67   _inc_bytes_used_before(0),
  68   _inc_recorded_rs_lengths(0),
  69   _inc_recorded_rs_lengths_diffs(0),
  70   _inc_predicted_elapsed_time_ms(0.0),
  71   _inc_predicted_elapsed_time_ms_diffs(0.0) {
  72 }
  73 
  74 G1CollectionSet::~G1CollectionSet() {
  75   if (_collection_set_regions != NULL) {
  76     FREE_C_HEAP_ARRAY(uint, _collection_set_regions);
  77   }
  78   free_optional_regions();
  79   clear_candidates();
  80 }
  81 
  82 void G1CollectionSet::init_region_lengths(uint eden_cset_region_length,
  83                                           uint survivor_cset_region_length) {
  84   assert_at_safepoint_on_vm_thread();
  85 
  86   _eden_region_length     = eden_cset_region_length;
  87   _survivor_region_length = survivor_cset_region_length;
  88 
  89   assert((size_t) young_region_length() == _collection_set_cur_length,
  90          "Young region length %u should match collection set length " SIZE_FORMAT, young_region_length(), _collection_set_cur_length);
  91 
  92   _old_region_length = 0;
  93   free_optional_regions();
  94 }
  95 
  96 void G1CollectionSet::initialize(uint max_region_length) {
  97   guarantee(_collection_set_regions == NULL, "Must only initialize once.");
  98   _collection_set_max_length = max_region_length;
  99   _collection_set_regions = NEW_C_HEAP_ARRAY(uint, max_region_length, mtGC);
 100 }
 101 








 102 void G1CollectionSet::free_optional_regions() {
 103   _num_optional_regions = 0;





 104 }
 105 
 106 void G1CollectionSet::clear_candidates() {
 107   delete _candidates;
 108   _candidates = NULL;
 109 }
 110 
 111 void G1CollectionSet::set_recorded_rs_lengths(size_t rs_lengths) {
 112   _recorded_rs_lengths = rs_lengths;
 113 }
 114 
 115 // Add the heap region at the head of the non-incremental collection set
 116 void G1CollectionSet::add_old_region(HeapRegion* hr) {
 117   assert_at_safepoint_on_vm_thread();
 118 
 119   assert(_inc_build_state == Active,
 120          "Precondition, actively building cset or adding optional later on");
 121   assert(hr->is_old(), "the region should be old");
 122 
 123   assert(!hr->in_collection_set(), "should not already be in the collection set");
 124   _g1h->register_old_region_with_region_attr(hr);
 125 
 126   _collection_set_regions[_collection_set_cur_length++] = hr->hrm_index();
 127   assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set now larger than maximum size.");
 128 
 129   _bytes_used_before += hr->used();
 130   _recorded_rs_lengths += hr->rem_set()->occupied();
 131   _old_region_length++;

 132 
 133   _g1h->old_set_remove(hr);
 134 }
 135 
 136 void G1CollectionSet::add_optional_region(HeapRegion* hr) {

 137   assert(hr->is_old(), "the region should be old");
 138   assert(!hr->in_collection_set(), "should not already be in the CSet");
 139 
 140   _g1h->register_optional_region_with_region_attr(hr);
 141 
 142   hr->set_index_in_opt_cset(_num_optional_regions++);




 143 }
 144 

 145 void G1CollectionSet::start_incremental_building() {
 146   assert(_collection_set_cur_length == 0, "Collection set must be empty before starting a new collection set.");
 147   assert(_inc_build_state == Inactive, "Precondition");
 148 
 149   _inc_bytes_used_before = 0;
 150 
 151   _inc_recorded_rs_lengths = 0;
 152   _inc_recorded_rs_lengths_diffs = 0;
 153   _inc_predicted_elapsed_time_ms = 0.0;
 154   _inc_predicted_elapsed_time_ms_diffs = 0.0;
 155 
 156   update_incremental_marker();
 157 }
 158 
 159 void G1CollectionSet::finalize_incremental_building() {
 160   assert(_inc_build_state == Active, "Precondition");
 161   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
 162 
 163   // The two "main" fields, _inc_recorded_rs_lengths and
 164   // _inc_predicted_elapsed_time_ms, are updated by the thread
 165   // that adds a new region to the CSet. Further updates by the
 166   // concurrent refinement thread that samples the young RSet lengths
 167   // are accumulated in the *_diffs fields. Here we add the diffs to
 168   // the "main" fields.
 169 
 170   if (_inc_recorded_rs_lengths_diffs >= 0) {
 171     _inc_recorded_rs_lengths += _inc_recorded_rs_lengths_diffs;
 172   } else {
 173     // This is defensive. The diff should in theory be always positive
 174     // as RSets can only grow between GCs. However, given that we
 175     // sample their size concurrently with other threads updating them
 176     // it's possible that we might get the wrong size back, which
 177     // could make the calculations somewhat inaccurate.
 178     size_t diffs = (size_t) (-_inc_recorded_rs_lengths_diffs);
 179     if (_inc_recorded_rs_lengths >= diffs) {
 180       _inc_recorded_rs_lengths -= diffs;
 181     } else {
 182       _inc_recorded_rs_lengths = 0;
 183     }
 184   }
 185   _inc_predicted_elapsed_time_ms += _inc_predicted_elapsed_time_ms_diffs;
 186 
 187   _inc_recorded_rs_lengths_diffs = 0;
 188   _inc_predicted_elapsed_time_ms_diffs = 0.0;
 189 }
 190 
 191 void G1CollectionSet::clear() {
 192   assert_at_safepoint_on_vm_thread();
 193   _collection_set_cur_length = 0;

 194 }
 195 
 196 void G1CollectionSet::iterate(HeapRegionClosure* cl) const {
 197   size_t len = _collection_set_cur_length;
 198   OrderAccess::loadload();
 199 
 200   for (uint i = 0; i < len; i++) {
 201     HeapRegion* r = _g1h->region_at(_collection_set_regions[i]);
 202     bool result = cl->do_heap_region(r);
 203     if (result) {
 204       cl->set_incomplete();
 205       return;
 206     }
 207   }
 208 }
 209 
 210 void G1CollectionSet::iterate_optional(HeapRegionClosure* cl) const {
 211   assert_at_safepoint();
 212 
 213   for (uint i = 0; i < _num_optional_regions; i++) {
 214     HeapRegion* r = _candidates->at(i);
 215     bool result = cl->do_heap_region(r);
 216     guarantee(!result, "Must not cancel iteration");
 217   }
 218 }
 219 
 220 void G1CollectionSet::iterate_incremental_part_from(HeapRegionClosure* cl, uint worker_id, uint total_workers) const {
 221   assert_at_safepoint();
 222 
 223   size_t len = _collection_set_cur_length - _inc_part_start;
 224   if (len == 0) {
 225     return;
 226   }
 227 
 228   size_t start_pos = (worker_id * len) / total_workers;
 229   size_t cur_pos = start_pos;
 230 
 231   do {
 232     HeapRegion* r = _g1h->region_at(_collection_set_regions[cur_pos + _inc_part_start]);
 233     bool result = cl->do_heap_region(r);
 234     guarantee(!result, "Must not cancel iteration");
 235 


 236     cur_pos++;
 237     if (cur_pos == len) {
 238       cur_pos = 0;
 239     }
 240   } while (cur_pos != start_pos);
 241 }
 242 
 243 void G1CollectionSet::update_young_region_prediction(HeapRegion* hr,
 244                                                      size_t new_rs_length) {
 245   // Update the CSet information that is dependent on the new RS length
 246   assert(hr->is_young(), "Precondition");
 247   assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint");
 248 
 249   // We could have updated _inc_recorded_rs_lengths and
 250   // _inc_predicted_elapsed_time_ms directly but we'd need to do
 251   // that atomically, as this code is executed by a concurrent
 252   // refinement thread, potentially concurrently with a mutator thread
 253   // allocating a new region and also updating the same fields. To
 254   // avoid the atomic operations we accumulate these updates on two
 255   // separate fields (*_diffs) and we'll just add them to the "main"


 299   // by the Young List sampling code.
 300   // Ignore calls to this due to retirement during full gc.
 301 
 302   if (!_g1h->collector_state()->in_full_gc()) {
 303     size_t rs_length = hr->rem_set()->occupied();
 304     double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr);
 305 
 306     // Cache the values we have added to the aggregated information
 307     // in the heap region in case we have to remove this region from
 308     // the incremental collection set, or it is updated by the
 309     // rset sampling code
 310     hr->set_recorded_rs_length(rs_length);
 311     hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
 312 
 313     _inc_recorded_rs_lengths += rs_length;
 314     _inc_predicted_elapsed_time_ms += region_elapsed_time_ms;
 315     _inc_bytes_used_before += hr->used();
 316   }
 317 
 318   assert(!hr->in_collection_set(), "invariant");
 319   _g1h->register_young_region_with_region_attr(hr);
 320 }
 321 
 322 void G1CollectionSet::add_survivor_regions(HeapRegion* hr) {
 323   assert(hr->is_survivor(), "Must only add survivor regions, but is %s", hr->get_type_str());
 324   add_young_region_common(hr);
 325 }
 326 
 327 void G1CollectionSet::add_eden_region(HeapRegion* hr) {
 328   assert(hr->is_eden(), "Must only add eden regions, but is %s", hr->get_type_str());
 329   add_young_region_common(hr);
 330 }
 331 
 332 #ifndef PRODUCT
 333 class G1VerifyYoungAgesClosure : public HeapRegionClosure {
 334 public:
 335   bool _valid;
 336 public:
 337   G1VerifyYoungAgesClosure() : HeapRegionClosure(), _valid(true) { }
 338 
 339   virtual bool do_heap_region(HeapRegion* r) {


 422 
 423   // Clear the fields that point to the survivor list - they are all young now.
 424   survivors->convert_to_eden();
 425 
 426   _bytes_used_before = _inc_bytes_used_before;
 427   time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0);
 428 
 429   log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
 430                             eden_region_length, survivor_region_length, _inc_predicted_elapsed_time_ms, target_pause_time_ms);
 431 
 432   // The number of recorded young regions is the incremental
 433   // collection set's current size
 434   set_recorded_rs_lengths(_inc_recorded_rs_lengths);
 435 
 436   double young_end_time_sec = os::elapsedTime();
 437   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
 438 
 439   return time_remaining_ms;
 440 }
 441 
























 442 static int compare_region_idx(const uint a, const uint b) {
 443   if (a > b) {
 444     return 1;
 445   } else if (a == b) {
 446     return 0;
 447   } else {
 448     return -1;
 449   }
 450 }
 451 
 452 void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
 453   double non_young_start_time_sec = os::elapsedTime();




 454 
 455   if (collector_state()->in_mixed_phase()) {
 456     candidates()->verify();
 457 
 458     uint num_initial_old_regions;
 459     uint num_optional_old_regions;
 460 
 461     _policy->calculate_old_collection_set_regions(candidates(),
 462                                                   time_remaining_ms,
 463                                                   num_initial_old_regions,
 464                                                   num_optional_old_regions);
 465 
 466     // Prepare initial old regions.
 467     move_candidates_to_collection_set(num_initial_old_regions);
 468 
 469     // Prepare optional old regions for evacuation.
 470     uint candidate_idx = candidates()->cur_idx();
 471     for (uint i = 0; i < num_optional_old_regions; i++) {
 472       add_optional_region(candidates()->at(candidate_idx + i));


























































 473     }
 474 
 475     candidates()->verify();
 476   }
 477 
 478   stop_incremental_building();
 479 









 480   double non_young_end_time_sec = os::elapsedTime();
 481   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
 482 
 483   QuickSort::sort(_collection_set_regions, _collection_set_cur_length, compare_region_idx, true);
 484 }
 485 
 486 void G1CollectionSet::move_candidates_to_collection_set(uint num_old_candidate_regions) {
 487   if (num_old_candidate_regions == 0) {
 488     return;
 489   }
 490   uint candidate_idx = candidates()->cur_idx();
 491   for (uint i = 0; i < num_old_candidate_regions; i++) {
 492     HeapRegion* r = candidates()->at(candidate_idx + i);
 493     // This potentially optional candidate region is going to be an actual collection
 494     // set region. Clear cset marker.
 495     _g1h->clear_region_attr(r);
 496     add_old_region(r);













 497   }
 498   candidates()->remove(num_old_candidate_regions);
 499 
 500   candidates()->verify();

 501 }
 502 
 503 void G1CollectionSet::finalize_initial_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) {
 504   double time_remaining_ms = finalize_young_part(target_pause_time_ms, survivor);
 505   finalize_old_part(time_remaining_ms);
 506 }
 507 
 508 bool G1CollectionSet::finalize_optional_for_evacuation(double remaining_pause_time) {
 509   update_incremental_marker();









 510 
 511   uint num_selected_regions;
 512   _policy->calculate_optional_collection_set_regions(candidates(),
 513                                                      _num_optional_regions,
 514                                                      remaining_pause_time,
 515                                                      num_selected_regions);
 516 
 517   move_candidates_to_collection_set(num_selected_regions);














 518 
 519   _num_optional_regions -= num_selected_regions;


 520 
 521   stop_incremental_building();
 522   return num_selected_regions > 0;
 523 }
 524 
 525 void G1CollectionSet::abandon_optional_collection_set(G1ParScanThreadStateSet* pss) {
 526   for (uint i = 0; i < _num_optional_regions; i++) {
 527     HeapRegion* r = candidates()->at(candidates()->cur_idx() + i);
 528     pss->record_unused_optional_region(r);
 529     _g1h->clear_region_attr(r);
 530     r->clear_index_in_opt_cset();
 531   }
 532   free_optional_regions();
 533 }
 534 
 535 #ifdef ASSERT
 536 class G1VerifyYoungCSetIndicesClosure : public HeapRegionClosure {
 537 private:
 538   size_t _young_length;
 539   int* _heap_region_indices;
 540 public:
 541   G1VerifyYoungCSetIndicesClosure(size_t young_length) : HeapRegionClosure(), _young_length(young_length) {
 542     _heap_region_indices = NEW_C_HEAP_ARRAY(int, young_length, mtGC);
 543     for (size_t i = 0; i < young_length; i++) {
 544       _heap_region_indices[i] = -1;
 545     }
 546   }
 547   ~G1VerifyYoungCSetIndicesClosure() {
 548     FREE_C_HEAP_ARRAY(int, _heap_region_indices);
 549   }
 550 
 551   virtual bool do_heap_region(HeapRegion* r) {
 552     const int idx = r->young_index_in_cset();




  42 }
  43 
  44 G1GCPhaseTimes* G1CollectionSet::phase_times() {
  45   return _policy->phase_times();
  46 }
  47 
  48 double G1CollectionSet::predict_region_elapsed_time_ms(HeapRegion* hr) {
  49   return _policy->predict_region_elapsed_time_ms(hr, collector_state()->in_young_only_phase());
  50 }
  51 
  52 G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy) :
  53   _g1h(g1h),
  54   _policy(policy),
  55   _candidates(NULL),
  56   _eden_region_length(0),
  57   _survivor_region_length(0),
  58   _old_region_length(0),
  59   _collection_set_regions(NULL),
  60   _collection_set_cur_length(0),
  61   _collection_set_max_length(0),
  62   _optional_regions(NULL),
  63   _optional_region_length(0),
  64   _optional_region_max_length(0),
  65   _bytes_used_before(0),
  66   _recorded_rs_lengths(0),
  67   _inc_build_state(Inactive),

  68   _inc_bytes_used_before(0),
  69   _inc_recorded_rs_lengths(0),
  70   _inc_recorded_rs_lengths_diffs(0),
  71   _inc_predicted_elapsed_time_ms(0.0),
  72   _inc_predicted_elapsed_time_ms_diffs(0.0) {
  73 }
  74 
  75 G1CollectionSet::~G1CollectionSet() {
  76   if (_collection_set_regions != NULL) {
  77     FREE_C_HEAP_ARRAY(uint, _collection_set_regions);
  78   }
  79   free_optional_regions();
  80   clear_candidates();
  81 }
  82 
  83 void G1CollectionSet::init_region_lengths(uint eden_cset_region_length,
  84                                           uint survivor_cset_region_length) {
  85   assert_at_safepoint_on_vm_thread();
  86 
  87   _eden_region_length     = eden_cset_region_length;
  88   _survivor_region_length = survivor_cset_region_length;
  89 
  90   assert((size_t) young_region_length() == _collection_set_cur_length,
  91          "Young region length %u should match collection set length " SIZE_FORMAT, young_region_length(), _collection_set_cur_length);
  92 
  93   _old_region_length      = 0;
  94   _optional_region_length = 0;
  95 }
  96 
  97 void G1CollectionSet::initialize(uint max_region_length) {
  98   guarantee(_collection_set_regions == NULL, "Must only initialize once.");
  99   _collection_set_max_length = max_region_length;
 100   _collection_set_regions = NEW_C_HEAP_ARRAY(uint, max_region_length, mtGC);
 101 }
 102 
 103 void G1CollectionSet::initialize_optional(uint max_length) {
 104   assert(_optional_regions == NULL, "Already initialized");
 105   assert(_optional_region_length == 0, "Already initialized");
 106   assert(_optional_region_max_length == 0, "Already initialized");
 107   _optional_region_max_length = max_length;
 108   _optional_regions = NEW_C_HEAP_ARRAY(HeapRegion*, _optional_region_max_length, mtGC);
 109 }
 110 
 111 void G1CollectionSet::free_optional_regions() {
 112   _optional_region_length = 0;
 113   _optional_region_max_length = 0;
 114   if (_optional_regions != NULL) {
 115     FREE_C_HEAP_ARRAY(HeapRegion*, _optional_regions);
 116     _optional_regions = NULL;
 117   }
 118 }
 119 
 120 void G1CollectionSet::clear_candidates() {
 121   delete _candidates;
 122   _candidates = NULL;
 123 }
 124 
 125 void G1CollectionSet::set_recorded_rs_lengths(size_t rs_lengths) {
 126   _recorded_rs_lengths = rs_lengths;
 127 }
 128 
 129 // Add the heap region at the head of the non-incremental collection set
 130 void G1CollectionSet::add_old_region(HeapRegion* hr) {
 131   assert_at_safepoint_on_vm_thread();
 132 
 133   assert(_inc_build_state == Active || hr->index_in_opt_cset() != G1OptionalCSet::InvalidCSetIndex,
 134          "Precondition, actively building cset or adding optional later on");
 135   assert(hr->is_old(), "the region should be old");
 136 
 137   assert(!hr->in_collection_set(), "should not already be in the CSet");
 138   _g1h->register_old_region_with_cset(hr);
 139 
 140   _collection_set_regions[_collection_set_cur_length++] = hr->hrm_index();
 141   assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set now larger than maximum size.");
 142 
 143   _bytes_used_before += hr->used();
 144   size_t rs_length = hr->rem_set()->occupied();
 145   _recorded_rs_lengths += rs_length;
 146   _old_region_length += 1;
 147 
 148   log_trace(gc, cset)("Added old region %d to collection set", hr->hrm_index());
 149 }
 150 
 151 void G1CollectionSet::add_optional_region(HeapRegion* hr) {
 152   assert(!optional_is_full(), "Precondition, must have room left for this region");
 153   assert(hr->is_old(), "the region should be old");
 154   assert(!hr->in_collection_set(), "should not already be in the CSet");
 155 
 156   _g1h->register_optional_region_with_cset(hr);
 157 
 158   _optional_regions[_optional_region_length] = hr;
 159   uint index = _optional_region_length++;
 160   hr->set_index_in_opt_cset(index);
 161 
 162   log_trace(gc, cset)("Added region %d to optional collection set (%u)", hr->hrm_index(), _optional_region_length);
 163 }
 164 
 165 // Initialize the per-collection-set information
 166 void G1CollectionSet::start_incremental_building() {
 167   assert(_collection_set_cur_length == 0, "Collection set must be empty before starting a new collection set.");
 168   assert(_inc_build_state == Inactive, "Precondition");
 169 
 170   _inc_bytes_used_before = 0;
 171 
 172   _inc_recorded_rs_lengths = 0;
 173   _inc_recorded_rs_lengths_diffs = 0;
 174   _inc_predicted_elapsed_time_ms = 0.0;
 175   _inc_predicted_elapsed_time_ms_diffs = 0.0;
 176   _inc_build_state = Active;

 177 }
 178 
 179 void G1CollectionSet::finalize_incremental_building() {
 180   assert(_inc_build_state == Active, "Precondition");
 181   assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
 182 
 183   // The two "main" fields, _inc_recorded_rs_lengths and
 184   // _inc_predicted_elapsed_time_ms, are updated by the thread
 185   // that adds a new region to the CSet. Further updates by the
 186   // concurrent refinement thread that samples the young RSet lengths
 187   // are accumulated in the *_diffs fields. Here we add the diffs to
 188   // the "main" fields.
 189 
 190   if (_inc_recorded_rs_lengths_diffs >= 0) {
 191     _inc_recorded_rs_lengths += _inc_recorded_rs_lengths_diffs;
 192   } else {
 193     // This is defensive. The diff should in theory be always positive
 194     // as RSets can only grow between GCs. However, given that we
 195     // sample their size concurrently with other threads updating them
 196     // it's possible that we might get the wrong size back, which
 197     // could make the calculations somewhat inaccurate.
 198     size_t diffs = (size_t) (-_inc_recorded_rs_lengths_diffs);
 199     if (_inc_recorded_rs_lengths >= diffs) {
 200       _inc_recorded_rs_lengths -= diffs;
 201     } else {
 202       _inc_recorded_rs_lengths = 0;
 203     }
 204   }
 205   _inc_predicted_elapsed_time_ms += _inc_predicted_elapsed_time_ms_diffs;
 206 
 207   _inc_recorded_rs_lengths_diffs = 0;
 208   _inc_predicted_elapsed_time_ms_diffs = 0.0;
 209 }
 210 
 211 void G1CollectionSet::clear() {
 212   assert_at_safepoint_on_vm_thread();
 213   _collection_set_cur_length = 0;
 214   _optional_region_length = 0;
 215 }
 216 
 217 void G1CollectionSet::iterate(HeapRegionClosure* cl) const {
 218   iterate_from(cl, 0, 1);




















 219 }
 220 
 221 void G1CollectionSet::iterate_from(HeapRegionClosure* cl, uint worker_id, uint total_workers) const {
 222   size_t len = _collection_set_cur_length;
 223   OrderAccess::loadload();

 224   if (len == 0) {
 225     return;
 226   }

 227   size_t start_pos = (worker_id * len) / total_workers;
 228   size_t cur_pos = start_pos;
 229 
 230   do {
 231     HeapRegion* r = _g1h->region_at(_collection_set_regions[cur_pos]);
 232     bool result = cl->do_heap_region(r);
 233     if (result) {
 234       cl->set_incomplete();
 235       return;
 236     }
 237     cur_pos++;
 238     if (cur_pos == len) {
 239       cur_pos = 0;
 240     }
 241   } while (cur_pos != start_pos);
 242 }
 243 
 244 void G1CollectionSet::update_young_region_prediction(HeapRegion* hr,
 245                                                      size_t new_rs_length) {
 246   // Update the CSet information that is dependent on the new RS length
 247   assert(hr->is_young(), "Precondition");
 248   assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint");
 249 
 250   // We could have updated _inc_recorded_rs_lengths and
 251   // _inc_predicted_elapsed_time_ms directly but we'd need to do
 252   // that atomically, as this code is executed by a concurrent
 253   // refinement thread, potentially concurrently with a mutator thread
 254   // allocating a new region and also updating the same fields. To
 255   // avoid the atomic operations we accumulate these updates on two
 256   // separate fields (*_diffs) and we'll just add them to the "main"


 300   // by the Young List sampling code.
 301   // Ignore calls to this due to retirement during full gc.
 302 
 303   if (!_g1h->collector_state()->in_full_gc()) {
 304     size_t rs_length = hr->rem_set()->occupied();
 305     double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr);
 306 
 307     // Cache the values we have added to the aggregated information
 308     // in the heap region in case we have to remove this region from
 309     // the incremental collection set, or it is updated by the
 310     // rset sampling code
 311     hr->set_recorded_rs_length(rs_length);
 312     hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
 313 
 314     _inc_recorded_rs_lengths += rs_length;
 315     _inc_predicted_elapsed_time_ms += region_elapsed_time_ms;
 316     _inc_bytes_used_before += hr->used();
 317   }
 318 
 319   assert(!hr->in_collection_set(), "invariant");
 320   _g1h->register_young_region_with_cset(hr);
 321 }
 322 
 323 void G1CollectionSet::add_survivor_regions(HeapRegion* hr) {
 324   assert(hr->is_survivor(), "Must only add survivor regions, but is %s", hr->get_type_str());
 325   add_young_region_common(hr);
 326 }
 327 
 328 void G1CollectionSet::add_eden_region(HeapRegion* hr) {
 329   assert(hr->is_eden(), "Must only add eden regions, but is %s", hr->get_type_str());
 330   add_young_region_common(hr);
 331 }
 332 
 333 #ifndef PRODUCT
 334 class G1VerifyYoungAgesClosure : public HeapRegionClosure {
 335 public:
 336   bool _valid;
 337 public:
 338   G1VerifyYoungAgesClosure() : HeapRegionClosure(), _valid(true) { }
 339 
 340   virtual bool do_heap_region(HeapRegion* r) {


 423 
 424   // Clear the fields that point to the survivor list - they are all young now.
 425   survivors->convert_to_eden();
 426 
 427   _bytes_used_before = _inc_bytes_used_before;
 428   time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0);
 429 
 430   log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
 431                             eden_region_length, survivor_region_length, _inc_predicted_elapsed_time_ms, target_pause_time_ms);
 432 
 433   // The number of recorded young regions is the incremental
 434   // collection set's current size
 435   set_recorded_rs_lengths(_inc_recorded_rs_lengths);
 436 
 437   double young_end_time_sec = os::elapsedTime();
 438   phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
 439 
 440   return time_remaining_ms;
 441 }
 442 
 443 void G1CollectionSet::add_as_old(HeapRegion* hr) {
 444   candidates()->pop_front(); // already have region via peek()
 445   _g1h->old_set_remove(hr);
 446   add_old_region(hr);
 447 }
 448 
 449 void G1CollectionSet::add_as_optional(HeapRegion* hr) {
 450   assert(_optional_regions != NULL, "Must not be called before array is allocated");
 451   candidates()->pop_front(); // already have region via peek()
 452   _g1h->old_set_remove(hr);
 453   add_optional_region(hr);
 454 }
 455 
 456 bool G1CollectionSet::optional_is_full() {
 457   assert(_optional_region_length <= _optional_region_max_length, "Invariant");
 458   return _optional_region_length == _optional_region_max_length;
 459 }
 460 
 461 void G1CollectionSet::clear_optional_region(const HeapRegion* hr) {
 462   assert(_optional_regions != NULL, "Must not be called before array is allocated");
 463   uint index = hr->index_in_opt_cset();
 464   _optional_regions[index] = NULL;
 465 }
 466 
 467 static int compare_region_idx(const uint a, const uint b) {
 468   if (a > b) {
 469     return 1;
 470   } else if (a == b) {
 471     return 0;
 472   } else {
 473     return -1;
 474   }
 475 }
 476 
 477 void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
 478   double non_young_start_time_sec = os::elapsedTime();
 479   double predicted_old_time_ms = 0.0;
 480   double predicted_optional_time_ms = 0.0;
 481   double optional_threshold_ms = time_remaining_ms * _policy->optional_prediction_fraction();
 482   uint expensive_region_num = 0;
 483 
 484   if (collector_state()->in_mixed_phase()) {
 485     candidates()->verify();
 486     const uint min_old_cset_length = _policy->calc_min_old_cset_length();
 487     const uint max_old_cset_length = MAX2(min_old_cset_length, _policy->calc_max_old_cset_length());
 488     bool check_time_remaining = _policy->adaptive_young_list_length();
 489 
 490     initialize_optional(max_old_cset_length - min_old_cset_length);
 491     log_debug(gc, ergo, cset)("Start adding old regions for mixed gc. min %u regions, max %u regions, "
 492                               "time remaining %1.2fms, optional threshold %1.2fms",
 493                               min_old_cset_length, max_old_cset_length, time_remaining_ms, optional_threshold_ms);
 494 
 495     HeapRegion* hr = candidates()->peek_front();
 496     while (hr != NULL) {
 497       if (old_region_length() + optional_region_length() >= max_old_cset_length) {
 498         // Added maximum number of old regions to the CSet.
 499         log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached max). "
 500                                   "old %u regions, optional %u regions",
 501                                   old_region_length(), optional_region_length());
 502         break;
 503       }
 504 
 505       // Stop adding regions if the remaining reclaimable space is
 506       // not above G1HeapWastePercent.
 507       size_t reclaimable_bytes = candidates()->remaining_reclaimable_bytes();
 508       double reclaimable_percent = _policy->reclaimable_bytes_percent(reclaimable_bytes);
 509       double threshold = (double) G1HeapWastePercent;
 510       if (reclaimable_percent <= threshold) {
 511         // We've added enough old regions that the amount of uncollected
 512         // reclaimable space is at or below the waste threshold. Stop
 513         // adding old regions to the CSet.
 514         log_debug(gc, ergo, cset)("Finish adding old regions to CSet (reclaimable percentage not over threshold). "
 515                                   "reclaimable: " SIZE_FORMAT "%s (%1.2f%%) threshold: " UINTX_FORMAT "%%",
 516                                   byte_size_in_proper_unit(reclaimable_bytes), proper_unit_for_byte_size(reclaimable_bytes),
 517                                   reclaimable_percent, G1HeapWastePercent);
 518         break;
 519       }
 520 
 521       double predicted_time_ms = predict_region_elapsed_time_ms(hr);
 522       time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
 523       // Add regions to old set until we reach minimum amount
 524       if (old_region_length() < min_old_cset_length) {
 525         predicted_old_time_ms += predicted_time_ms;
 526         add_as_old(hr);
 527         // Record the number of regions added when no time remaining
 528         if (time_remaining_ms == 0.0) {
 529           expensive_region_num++;
 530         }
 531       } else {
 532         // In the non-auto-tuning case, we'll finish adding regions
 533         // to the CSet if we reach the minimum.
 534         if (!check_time_remaining) {
 535           log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached min).");
 536           break;
 537         }
 538         // Keep adding regions to old set until we reach optional threshold
 539         if (time_remaining_ms > optional_threshold_ms) {
 540           predicted_old_time_ms += predicted_time_ms;
 541           add_as_old(hr);
 542         } else if (time_remaining_ms > 0) {
 543           // Keep adding optional regions until time is up
 544           if (!optional_is_full()) {
 545             predicted_optional_time_ms += predicted_time_ms;
 546             add_as_optional(hr);
 547           } else {
 548             log_debug(gc, ergo, cset)("Finish adding old regions to CSet (optional set full).");
 549             break;
 550           }
 551         } else {
 552           log_debug(gc, ergo, cset)("Finish adding old regions to CSet (predicted time is too high).");
 553           break;
 554         }
 555       }
 556       hr = candidates()->peek_front();
 557     }
 558     if (hr == NULL) {
 559       log_debug(gc, ergo, cset)("Finish adding old regions to CSet (candidate old regions not available)");
 560     }
 561 
 562     candidates()->verify();
 563   }
 564 
 565   stop_incremental_building();
 566 
 567   log_debug(gc, ergo, cset)("Finish choosing CSet regions old: %u, optional: %u, "
 568                             "predicted old time: %1.2fms, predicted optional time: %1.2fms, time remaining: %1.2f",
 569                             old_region_length(), optional_region_length(),
 570                             predicted_old_time_ms, predicted_optional_time_ms, time_remaining_ms);
 571   if (expensive_region_num > 0) {
 572     log_debug(gc, ergo, cset)("CSet contains %u old regions that were added although the predicted time was too high.",
 573                               expensive_region_num);
 574   }
 575 
 576   double non_young_end_time_sec = os::elapsedTime();
 577   phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
 578 
 579   QuickSort::sort(_collection_set_regions, _collection_set_cur_length, compare_region_idx, true);
 580 }
 581 
 582 HeapRegion* G1OptionalCSet::region_at(uint index) {
 583   return _cset->optional_region_at(index);
 584 }
 585 
 586 void G1OptionalCSet::prepare_evacuation(double time_limit) {
 587   assert(_current_index == _current_limit, "Before prepare no regions should be ready for evac");
 588 
 589   uint prepared_regions = 0;
 590   double prediction_ms = 0;
 591 
 592   _prepare_failed = true;
 593   for (uint i = _current_index; i < _cset->optional_region_length(); i++) {
 594     HeapRegion* hr = region_at(i);
 595     prediction_ms += _cset->predict_region_elapsed_time_ms(hr);
 596     if (prediction_ms > time_limit) {
 597       log_debug(gc, cset)("Prepared %u regions for optional evacuation. Predicted time: %.3fms", prepared_regions, prediction_ms);
 598       return;
 599     }
 600 
 601     // This region will be included in the next optional evacuation.
 602     prepare_to_evacuate_optional_region(hr);
 603     prepared_regions++;
 604     _current_limit++;
 605     _prepare_failed = false;
 606   }

 607 
 608   log_debug(gc, cset)("Prepared all %u regions for optional evacuation. Predicted time: %.3fms",
 609                       prepared_regions, prediction_ms);
 610 }
 611 
 612 bool G1OptionalCSet::prepare_failed() {
 613   return _prepare_failed;

 614 }
 615 
 616 void G1OptionalCSet::complete_evacuation() {
 617   _evacuation_failed = false;
 618   for (uint i = _current_index; i < _current_limit; i++) {
 619     HeapRegion* hr = region_at(i);
 620     _cset->clear_optional_region(hr);
 621     if (hr->evacuation_failed()){
 622       _evacuation_failed = true;
 623     }
 624   }
 625   _current_index = _current_limit;
 626 }
 627 
 628 bool G1OptionalCSet::evacuation_failed() {
 629   return _evacuation_failed;
 630 }


 631 
 632 G1OptionalCSet::~G1OptionalCSet() {
 633   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 634   while (!is_empty()) {
 635     // We want to return regions not evacuated to the collection set candidates
 636     // in reverse order to maintain the old order.
 637     HeapRegion* hr = _cset->remove_last_optional_region();
 638     assert(hr != NULL, "Should be valid region left");
 639     _pset->record_unused_optional_region(hr);
 640     g1h->old_set_add(hr);
 641     g1h->clear_in_cset(hr);
 642     hr->set_index_in_opt_cset(InvalidCSetIndex);
 643     _cset->candidates()->push_front(hr);
 644   }
 645   _cset->free_optional_regions();
 646 }
 647 
 648 uint G1OptionalCSet::size() {
 649   return _cset->optional_region_length() - _current_index;
 650 }
 651 
 652 bool G1OptionalCSet::is_empty() {
 653   return size() == 0;
 654 }
 655 
 656 void G1OptionalCSet::prepare_to_evacuate_optional_region(HeapRegion* hr) {
 657   log_trace(gc, cset)("Adding region %u for optional evacuation", hr->hrm_index());
 658   G1CollectedHeap::heap()->clear_in_cset(hr);
 659   _cset->add_old_region(hr);




 660 }
 661 
 662 #ifdef ASSERT
 663 class G1VerifyYoungCSetIndicesClosure : public HeapRegionClosure {
 664 private:
 665   size_t _young_length;
 666   int* _heap_region_indices;
 667 public:
 668   G1VerifyYoungCSetIndicesClosure(size_t young_length) : HeapRegionClosure(), _young_length(young_length) {
 669     _heap_region_indices = NEW_C_HEAP_ARRAY(int, young_length, mtGC);
 670     for (size_t i = 0; i < young_length; i++) {
 671       _heap_region_indices[i] = -1;
 672     }
 673   }
 674   ~G1VerifyYoungCSetIndicesClosure() {
 675     FREE_C_HEAP_ARRAY(int, _heap_region_indices);
 676   }
 677 
 678   virtual bool do_heap_region(HeapRegion* r) {
 679     const int idx = r->young_index_in_cset();


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