1 /*
   2  * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "code/codeCache.hpp"
  27 #include "gc/parallel/adjoiningGenerations.hpp"
  28 #include "gc/parallel/adjoiningVirtualSpaces.hpp"
  29 #include "gc/parallel/gcTaskManager.hpp"
  30 #include "gc/parallel/generationSizer.hpp"
  31 #include "gc/parallel/objectStartArray.inline.hpp"
  32 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
  33 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
  34 #include "gc/parallel/psMarkSweep.hpp"
  35 #include "gc/parallel/psMemoryPool.hpp"
  36 #include "gc/parallel/psParallelCompact.inline.hpp"
  37 #include "gc/parallel/psPromotionManager.hpp"
  38 #include "gc/parallel/psScavenge.hpp"
  39 #include "gc/parallel/vmPSOperations.hpp"
  40 #include "gc/shared/gcHeapSummary.hpp"
  41 #include "gc/shared/gcLocker.inline.hpp"
  42 #include "gc/shared/gcWhen.hpp"
  43 #include "logging/log.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "runtime/handles.inline.hpp"
  46 #include "runtime/java.hpp"
  47 #include "runtime/vmThread.hpp"
  48 #include "services/memoryManager.hpp"
  49 #include "services/memTracker.hpp"
  50 #include "utilities/vmError.hpp"
  51 
  52 PSYoungGen*  ParallelScavengeHeap::_young_gen = NULL;
  53 PSOldGen*    ParallelScavengeHeap::_old_gen = NULL;
  54 PSAdaptiveSizePolicy* ParallelScavengeHeap::_size_policy = NULL;
  55 PSGCAdaptivePolicyCounters* ParallelScavengeHeap::_gc_policy_counters = NULL;
  56 GCTaskManager* ParallelScavengeHeap::_gc_task_manager = NULL;
  57 
  58 jint ParallelScavengeHeap::initialize() {
  59   const size_t heap_size = _collector_policy->max_heap_byte_size();
  60 
  61   ReservedSpace heap_rs = Universe::reserve_heap(heap_size, _collector_policy->heap_alignment());
  62 
  63   os::trace_page_sizes("Heap",
  64                        _collector_policy->min_heap_byte_size(),
  65                        heap_size,
  66                        generation_alignment(),
  67                        heap_rs.base(),
  68                        heap_rs.size());
  69 
  70   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
  71 
  72   PSCardTable* card_table = new PSCardTable(reserved_region());
  73   card_table->initialize();
  74   CardTableModRefBS* const barrier_set = new CardTableModRefBS(card_table);
  75   barrier_set->initialize();
  76   set_barrier_set(barrier_set);
  77 
  78   // Make up the generations
  79   // Calculate the maximum size that a generation can grow.  This
  80   // includes growth into the other generation.  Note that the
  81   // parameter _max_gen_size is kept as the maximum
  82   // size of the generation as the boundaries currently stand.
  83   // _max_gen_size is still used as that value.
  84   double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;
  85   double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
  86 
  87   _gens = new AdjoiningGenerations(heap_rs, _collector_policy, generation_alignment());
  88 
  89   _old_gen = _gens->old_gen();
  90   _young_gen = _gens->young_gen();
  91 
  92   const size_t eden_capacity = _young_gen->eden_space()->capacity_in_bytes();
  93   const size_t old_capacity = _old_gen->capacity_in_bytes();
  94   const size_t initial_promo_size = MIN2(eden_capacity, old_capacity);
  95   _size_policy =
  96     new PSAdaptiveSizePolicy(eden_capacity,
  97                              initial_promo_size,
  98                              young_gen()->to_space()->capacity_in_bytes(),
  99                              _collector_policy->gen_alignment(),
 100                              max_gc_pause_sec,
 101                              max_gc_minor_pause_sec,
 102                              GCTimeRatio
 103                              );
 104 
 105   assert(!UseAdaptiveGCBoundary ||
 106     (old_gen()->virtual_space()->high_boundary() ==
 107      young_gen()->virtual_space()->low_boundary()),
 108     "Boundaries must meet");
 109   // initialize the policy counters - 2 collectors, 2 generations
 110   _gc_policy_counters =
 111     new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 2, _size_policy);
 112 
 113   // Set up the GCTaskManager
 114   _gc_task_manager = GCTaskManager::create(ParallelGCThreads);
 115 
 116   if (UseParallelOldGC && !PSParallelCompact::initialize()) {
 117     return JNI_ENOMEM;
 118   }
 119 
 120   return JNI_OK;
 121 }
 122 
 123 void ParallelScavengeHeap::initialize_serviceability() {
 124 
 125   _eden_pool = new EdenMutableSpacePool(_young_gen,
 126                                         _young_gen->eden_space(),
 127                                         "PS Eden Space",
 128                                         false /* support_usage_threshold */);
 129 
 130   _survivor_pool = new SurvivorMutableSpacePool(_young_gen,
 131                                                 "PS Survivor Space",
 132                                                 false /* support_usage_threshold */);
 133 
 134   _old_pool = new PSGenerationPool(_old_gen,
 135                                    "PS Old Gen",
 136                                    true /* support_usage_threshold */);
 137 
 138   _young_manager = new GCMemoryManager("PS Scavenge", "end of minor GC");
 139   _old_manager = new GCMemoryManager("PS MarkSweep", "end of major GC");
 140 
 141   _old_manager->add_pool(_eden_pool);
 142   _old_manager->add_pool(_survivor_pool);
 143   _old_manager->add_pool(_old_pool);
 144 
 145   _young_manager->add_pool(_eden_pool);
 146   _young_manager->add_pool(_survivor_pool);
 147 
 148 }
 149 
 150 void ParallelScavengeHeap::post_initialize() {
 151   CollectedHeap::post_initialize();
 152   // Need to init the tenuring threshold
 153   PSScavenge::initialize();
 154   if (UseParallelOldGC) {
 155     PSParallelCompact::post_initialize();
 156   } else {
 157     PSMarkSweep::initialize();
 158   }
 159   PSPromotionManager::initialize();
 160 }
 161 
 162 void ParallelScavengeHeap::update_counters() {
 163   young_gen()->update_counters();
 164   old_gen()->update_counters();
 165   MetaspaceCounters::update_performance_counters();
 166   CompressedClassSpaceCounters::update_performance_counters();
 167 }
 168 
 169 size_t ParallelScavengeHeap::capacity() const {
 170   size_t value = young_gen()->capacity_in_bytes() + old_gen()->capacity_in_bytes();
 171   return value;
 172 }
 173 
 174 size_t ParallelScavengeHeap::used() const {
 175   size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes();
 176   return value;
 177 }
 178 
 179 bool ParallelScavengeHeap::is_maximal_no_gc() const {
 180   return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc();
 181 }
 182 
 183 
 184 size_t ParallelScavengeHeap::max_capacity() const {
 185   size_t estimated = reserved_region().byte_size();
 186   if (UseAdaptiveSizePolicy) {
 187     estimated -= _size_policy->max_survivor_size(young_gen()->max_size());
 188   } else {
 189     estimated -= young_gen()->to_space()->capacity_in_bytes();
 190   }
 191   return MAX2(estimated, capacity());
 192 }
 193 
 194 bool ParallelScavengeHeap::is_in(const void* p) const {
 195   return young_gen()->is_in(p) || old_gen()->is_in(p);
 196 }
 197 
 198 bool ParallelScavengeHeap::is_in_reserved(const void* p) const {
 199   return young_gen()->is_in_reserved(p) || old_gen()->is_in_reserved(p);
 200 }
 201 
 202 // There are two levels of allocation policy here.
 203 //
 204 // When an allocation request fails, the requesting thread must invoke a VM
 205 // operation, transfer control to the VM thread, and await the results of a
 206 // garbage collection. That is quite expensive, and we should avoid doing it
 207 // multiple times if possible.
 208 //
 209 // To accomplish this, we have a basic allocation policy, and also a
 210 // failed allocation policy.
 211 //
 212 // The basic allocation policy controls how you allocate memory without
 213 // attempting garbage collection. It is okay to grab locks and
 214 // expand the heap, if that can be done without coming to a safepoint.
 215 // It is likely that the basic allocation policy will not be very
 216 // aggressive.
 217 //
 218 // The failed allocation policy is invoked from the VM thread after
 219 // the basic allocation policy is unable to satisfy a mem_allocate
 220 // request. This policy needs to cover the entire range of collection,
 221 // heap expansion, and out-of-memory conditions. It should make every
 222 // attempt to allocate the requested memory.
 223 
 224 // Basic allocation policy. Should never be called at a safepoint, or
 225 // from the VM thread.
 226 //
 227 // This method must handle cases where many mem_allocate requests fail
 228 // simultaneously. When that happens, only one VM operation will succeed,
 229 // and the rest will not be executed. For that reason, this method loops
 230 // during failed allocation attempts. If the java heap becomes exhausted,
 231 // we rely on the size_policy object to force a bail out.
 232 HeapWord* ParallelScavengeHeap::mem_allocate(
 233                                      size_t size,
 234                                      bool* gc_overhead_limit_was_exceeded) {
 235   assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");
 236   assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");
 237   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 238 
 239   // In general gc_overhead_limit_was_exceeded should be false so
 240   // set it so here and reset it to true only if the gc time
 241   // limit is being exceeded as checked below.
 242   *gc_overhead_limit_was_exceeded = false;
 243 
 244   HeapWord* result = young_gen()->allocate(size);
 245 
 246   uint loop_count = 0;
 247   uint gc_count = 0;
 248   uint gclocker_stalled_count = 0;
 249 
 250   while (result == NULL) {
 251     // We don't want to have multiple collections for a single filled generation.
 252     // To prevent this, each thread tracks the total_collections() value, and if
 253     // the count has changed, does not do a new collection.
 254     //
 255     // The collection count must be read only while holding the heap lock. VM
 256     // operations also hold the heap lock during collections. There is a lock
 257     // contention case where thread A blocks waiting on the Heap_lock, while
 258     // thread B is holding it doing a collection. When thread A gets the lock,
 259     // the collection count has already changed. To prevent duplicate collections,
 260     // The policy MUST attempt allocations during the same period it reads the
 261     // total_collections() value!
 262     {
 263       MutexLocker ml(Heap_lock);
 264       gc_count = total_collections();
 265 
 266       result = young_gen()->allocate(size);
 267       if (result != NULL) {
 268         return result;
 269       }
 270 
 271       // If certain conditions hold, try allocating from the old gen.
 272       result = mem_allocate_old_gen(size);
 273       if (result != NULL) {
 274         return result;
 275       }
 276 
 277       if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
 278         return NULL;
 279       }
 280 
 281       // Failed to allocate without a gc.
 282       if (GCLocker::is_active_and_needs_gc()) {
 283         // If this thread is not in a jni critical section, we stall
 284         // the requestor until the critical section has cleared and
 285         // GC allowed. When the critical section clears, a GC is
 286         // initiated by the last thread exiting the critical section; so
 287         // we retry the allocation sequence from the beginning of the loop,
 288         // rather than causing more, now probably unnecessary, GC attempts.
 289         JavaThread* jthr = JavaThread::current();
 290         if (!jthr->in_critical()) {
 291           MutexUnlocker mul(Heap_lock);
 292           GCLocker::stall_until_clear();
 293           gclocker_stalled_count += 1;
 294           continue;
 295         } else {
 296           if (CheckJNICalls) {
 297             fatal("Possible deadlock due to allocating while"
 298                   " in jni critical section");
 299           }
 300           return NULL;
 301         }
 302       }
 303     }
 304 
 305     if (result == NULL) {
 306       // Generate a VM operation
 307       VM_ParallelGCFailedAllocation op(size, gc_count);
 308       VMThread::execute(&op);
 309 
 310       // Did the VM operation execute? If so, return the result directly.
 311       // This prevents us from looping until time out on requests that can
 312       // not be satisfied.
 313       if (op.prologue_succeeded()) {
 314         assert(is_in_or_null(op.result()), "result not in heap");
 315 
 316         // If GC was locked out during VM operation then retry allocation
 317         // and/or stall as necessary.
 318         if (op.gc_locked()) {
 319           assert(op.result() == NULL, "must be NULL if gc_locked() is true");
 320           continue;  // retry and/or stall as necessary
 321         }
 322 
 323         // Exit the loop if the gc time limit has been exceeded.
 324         // The allocation must have failed above ("result" guarding
 325         // this path is NULL) and the most recent collection has exceeded the
 326         // gc overhead limit (although enough may have been collected to
 327         // satisfy the allocation).  Exit the loop so that an out-of-memory
 328         // will be thrown (return a NULL ignoring the contents of
 329         // op.result()),
 330         // but clear gc_overhead_limit_exceeded so that the next collection
 331         // starts with a clean slate (i.e., forgets about previous overhead
 332         // excesses).  Fill op.result() with a filler object so that the
 333         // heap remains parsable.
 334         const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
 335         const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
 336 
 337         if (limit_exceeded && softrefs_clear) {
 338           *gc_overhead_limit_was_exceeded = true;
 339           size_policy()->set_gc_overhead_limit_exceeded(false);
 340           log_trace(gc)("ParallelScavengeHeap::mem_allocate: return NULL because gc_overhead_limit_exceeded is set");
 341           if (op.result() != NULL) {
 342             CollectedHeap::fill_with_object(op.result(), size);
 343           }
 344           return NULL;
 345         }
 346 
 347         return op.result();
 348       }
 349     }
 350 
 351     // The policy object will prevent us from looping forever. If the
 352     // time spent in gc crosses a threshold, we will bail out.
 353     loop_count++;
 354     if ((result == NULL) && (QueuedAllocationWarningCount > 0) &&
 355         (loop_count % QueuedAllocationWarningCount == 0)) {
 356       log_warning(gc)("ParallelScavengeHeap::mem_allocate retries %d times", loop_count);
 357       log_warning(gc)("\tsize=" SIZE_FORMAT, size);
 358     }
 359   }
 360 
 361   return result;
 362 }
 363 
 364 // A "death march" is a series of ultra-slow allocations in which a full gc is
 365 // done before each allocation, and after the full gc the allocation still
 366 // cannot be satisfied from the young gen.  This routine detects that condition;
 367 // it should be called after a full gc has been done and the allocation
 368 // attempted from the young gen. The parameter 'addr' should be the result of
 369 // that young gen allocation attempt.
 370 void
 371 ParallelScavengeHeap::death_march_check(HeapWord* const addr, size_t size) {
 372   if (addr != NULL) {
 373     _death_march_count = 0;  // death march has ended
 374   } else if (_death_march_count == 0) {
 375     if (should_alloc_in_eden(size)) {
 376       _death_march_count = 1;    // death march has started
 377     }
 378   }
 379 }
 380 
 381 HeapWord* ParallelScavengeHeap::mem_allocate_old_gen(size_t size) {
 382   if (!should_alloc_in_eden(size) || GCLocker::is_active_and_needs_gc()) {
 383     // Size is too big for eden, or gc is locked out.
 384     return old_gen()->allocate(size);
 385   }
 386 
 387   // If a "death march" is in progress, allocate from the old gen a limited
 388   // number of times before doing a GC.
 389   if (_death_march_count > 0) {
 390     if (_death_march_count < 64) {
 391       ++_death_march_count;
 392       return old_gen()->allocate(size);
 393     } else {
 394       _death_march_count = 0;
 395     }
 396   }
 397   return NULL;
 398 }
 399 
 400 void ParallelScavengeHeap::do_full_collection(bool clear_all_soft_refs) {
 401   if (UseParallelOldGC) {
 402     // The do_full_collection() parameter clear_all_soft_refs
 403     // is interpreted here as maximum_compaction which will
 404     // cause SoftRefs to be cleared.
 405     bool maximum_compaction = clear_all_soft_refs;
 406     PSParallelCompact::invoke(maximum_compaction);
 407   } else {
 408     PSMarkSweep::invoke(clear_all_soft_refs);
 409   }
 410 }
 411 
 412 // Failed allocation policy. Must be called from the VM thread, and
 413 // only at a safepoint! Note that this method has policy for allocation
 414 // flow, and NOT collection policy. So we do not check for gc collection
 415 // time over limit here, that is the responsibility of the heap specific
 416 // collection methods. This method decides where to attempt allocations,
 417 // and when to attempt collections, but no collection specific policy.
 418 HeapWord* ParallelScavengeHeap::failed_mem_allocate(size_t size) {
 419   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 420   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 421   assert(!is_gc_active(), "not reentrant");
 422   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 423 
 424   // We assume that allocation in eden will fail unless we collect.
 425 
 426   // First level allocation failure, scavenge and allocate in young gen.
 427   GCCauseSetter gccs(this, GCCause::_allocation_failure);
 428   const bool invoked_full_gc = PSScavenge::invoke();
 429   HeapWord* result = young_gen()->allocate(size);
 430 
 431   // Second level allocation failure.
 432   //   Mark sweep and allocate in young generation.
 433   if (result == NULL && !invoked_full_gc) {
 434     do_full_collection(false);
 435     result = young_gen()->allocate(size);
 436   }
 437 
 438   death_march_check(result, size);
 439 
 440   // Third level allocation failure.
 441   //   After mark sweep and young generation allocation failure,
 442   //   allocate in old generation.
 443   if (result == NULL) {
 444     result = old_gen()->allocate(size);
 445   }
 446 
 447   // Fourth level allocation failure. We're running out of memory.
 448   //   More complete mark sweep and allocate in young generation.
 449   if (result == NULL) {
 450     do_full_collection(true);
 451     result = young_gen()->allocate(size);
 452   }
 453 
 454   // Fifth level allocation failure.
 455   //   After more complete mark sweep, allocate in old generation.
 456   if (result == NULL) {
 457     result = old_gen()->allocate(size);
 458   }
 459 
 460   return result;
 461 }
 462 
 463 void ParallelScavengeHeap::ensure_parsability(bool retire_tlabs) {
 464   CollectedHeap::ensure_parsability(retire_tlabs);
 465   young_gen()->eden_space()->ensure_parsability();
 466 }
 467 
 468 size_t ParallelScavengeHeap::tlab_capacity(Thread* thr) const {
 469   return young_gen()->eden_space()->tlab_capacity(thr);
 470 }
 471 
 472 size_t ParallelScavengeHeap::tlab_used(Thread* thr) const {
 473   return young_gen()->eden_space()->tlab_used(thr);
 474 }
 475 
 476 size_t ParallelScavengeHeap::unsafe_max_tlab_alloc(Thread* thr) const {
 477   return young_gen()->eden_space()->unsafe_max_tlab_alloc(thr);
 478 }
 479 
 480 HeapWord* ParallelScavengeHeap::allocate_new_tlab(size_t size) {
 481   return young_gen()->allocate(size);
 482 }
 483 
 484 void ParallelScavengeHeap::accumulate_statistics_all_tlabs() {
 485   CollectedHeap::accumulate_statistics_all_tlabs();
 486 }
 487 
 488 void ParallelScavengeHeap::resize_all_tlabs() {
 489   CollectedHeap::resize_all_tlabs();
 490 }
 491 
 492 // This method is used by System.gc() and JVMTI.
 493 void ParallelScavengeHeap::collect(GCCause::Cause cause) {
 494   assert(!Heap_lock->owned_by_self(),
 495     "this thread should not own the Heap_lock");
 496 
 497   uint gc_count      = 0;
 498   uint full_gc_count = 0;
 499   {
 500     MutexLocker ml(Heap_lock);
 501     // This value is guarded by the Heap_lock
 502     gc_count      = total_collections();
 503     full_gc_count = total_full_collections();
 504   }
 505 
 506   VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause);
 507   VMThread::execute(&op);
 508 }
 509 
 510 void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) {
 511   young_gen()->object_iterate(cl);
 512   old_gen()->object_iterate(cl);
 513 }
 514 
 515 
 516 HeapWord* ParallelScavengeHeap::block_start(const void* addr) const {
 517   if (young_gen()->is_in_reserved(addr)) {
 518     assert(young_gen()->is_in(addr),
 519            "addr should be in allocated part of young gen");
 520     // called from os::print_location by find or VMError
 521     if (Debugging || VMError::fatal_error_in_progress())  return NULL;
 522     Unimplemented();
 523   } else if (old_gen()->is_in_reserved(addr)) {
 524     assert(old_gen()->is_in(addr),
 525            "addr should be in allocated part of old gen");
 526     return old_gen()->start_array()->object_start((HeapWord*)addr);
 527   }
 528   return 0;
 529 }
 530 
 531 size_t ParallelScavengeHeap::block_size(const HeapWord* addr) const {
 532   return oop(addr)->size();
 533 }
 534 
 535 bool ParallelScavengeHeap::block_is_obj(const HeapWord* addr) const {
 536   return block_start(addr) == addr;
 537 }
 538 
 539 jlong ParallelScavengeHeap::millis_since_last_gc() {
 540   return UseParallelOldGC ?
 541     PSParallelCompact::millis_since_last_gc() :
 542     PSMarkSweep::millis_since_last_gc();
 543 }
 544 
 545 void ParallelScavengeHeap::prepare_for_verify() {
 546   ensure_parsability(false);  // no need to retire TLABs for verification
 547 }
 548 
 549 PSHeapSummary ParallelScavengeHeap::create_ps_heap_summary() {
 550   PSOldGen* old = old_gen();
 551   HeapWord* old_committed_end = (HeapWord*)old->virtual_space()->committed_high_addr();
 552   VirtualSpaceSummary old_summary(old->reserved().start(), old_committed_end, old->reserved().end());
 553   SpaceSummary old_space(old->reserved().start(), old_committed_end, old->used_in_bytes());
 554 
 555   PSYoungGen* young = young_gen();
 556   VirtualSpaceSummary young_summary(young->reserved().start(),
 557     (HeapWord*)young->virtual_space()->committed_high_addr(), young->reserved().end());
 558 
 559   MutableSpace* eden = young_gen()->eden_space();
 560   SpaceSummary eden_space(eden->bottom(), eden->end(), eden->used_in_bytes());
 561 
 562   MutableSpace* from = young_gen()->from_space();
 563   SpaceSummary from_space(from->bottom(), from->end(), from->used_in_bytes());
 564 
 565   MutableSpace* to = young_gen()->to_space();
 566   SpaceSummary to_space(to->bottom(), to->end(), to->used_in_bytes());
 567 
 568   VirtualSpaceSummary heap_summary = create_heap_space_summary();
 569   return PSHeapSummary(heap_summary, used(), old_summary, old_space, young_summary, eden_space, from_space, to_space);
 570 }
 571 
 572 void ParallelScavengeHeap::print_on(outputStream* st) const {
 573   young_gen()->print_on(st);
 574   old_gen()->print_on(st);
 575   MetaspaceAux::print_on(st);
 576 }
 577 
 578 void ParallelScavengeHeap::print_on_error(outputStream* st) const {
 579   this->CollectedHeap::print_on_error(st);
 580 
 581   if (UseParallelOldGC) {
 582     st->cr();
 583     PSParallelCompact::print_on_error(st);
 584   }
 585 }
 586 
 587 void ParallelScavengeHeap::gc_threads_do(ThreadClosure* tc) const {
 588   PSScavenge::gc_task_manager()->threads_do(tc);
 589 }
 590 
 591 void ParallelScavengeHeap::print_gc_threads_on(outputStream* st) const {
 592   PSScavenge::gc_task_manager()->print_threads_on(st);
 593 }
 594 
 595 void ParallelScavengeHeap::print_tracing_info() const {
 596   AdaptiveSizePolicyOutput::print();
 597   log_debug(gc, heap, exit)("Accumulated young generation GC time %3.7f secs", PSScavenge::accumulated_time()->seconds());
 598   log_debug(gc, heap, exit)("Accumulated old generation GC time %3.7f secs",
 599       UseParallelOldGC ? PSParallelCompact::accumulated_time()->seconds() : PSMarkSweep::accumulated_time()->seconds());
 600 }
 601 
 602 
 603 void ParallelScavengeHeap::verify(VerifyOption option /* ignored */) {
 604   // Why do we need the total_collections()-filter below?
 605   if (total_collections() > 0) {
 606     log_debug(gc, verify)("Tenured");
 607     old_gen()->verify();
 608 
 609     log_debug(gc, verify)("Eden");
 610     young_gen()->verify();
 611   }
 612 }
 613 
 614 void ParallelScavengeHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
 615   const PSHeapSummary& heap_summary = create_ps_heap_summary();
 616   gc_tracer->report_gc_heap_summary(when, heap_summary);
 617 
 618   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
 619   gc_tracer->report_metaspace_summary(when, metaspace_summary);
 620 }
 621 
 622 ParallelScavengeHeap* ParallelScavengeHeap::heap() {
 623   CollectedHeap* heap = Universe::heap();
 624   assert(heap != NULL, "Uninitialized access to ParallelScavengeHeap::heap()");
 625   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Not a ParallelScavengeHeap");
 626   return (ParallelScavengeHeap*)heap;
 627 }
 628 
 629 CardTableModRefBS* ParallelScavengeHeap::barrier_set() {
 630   return barrier_set_cast<CardTableModRefBS>(CollectedHeap::barrier_set());
 631 }
 632 
 633 PSCardTable* ParallelScavengeHeap::card_table() {
 634   return static_cast<PSCardTable*>(barrier_set()->card_table());
 635 }
 636 
 637 // Before delegating the resize to the young generation,
 638 // the reserved space for the young and old generations
 639 // may be changed to accommodate the desired resize.
 640 void ParallelScavengeHeap::resize_young_gen(size_t eden_size,
 641     size_t survivor_size) {
 642   if (UseAdaptiveGCBoundary) {
 643     if (size_policy()->bytes_absorbed_from_eden() != 0) {
 644       size_policy()->reset_bytes_absorbed_from_eden();
 645       return;  // The generation changed size already.
 646     }
 647     gens()->adjust_boundary_for_young_gen_needs(eden_size, survivor_size);
 648   }
 649 
 650   // Delegate the resize to the generation.
 651   _young_gen->resize(eden_size, survivor_size);
 652 }
 653 
 654 // Before delegating the resize to the old generation,
 655 // the reserved space for the young and old generations
 656 // may be changed to accommodate the desired resize.
 657 void ParallelScavengeHeap::resize_old_gen(size_t desired_free_space) {
 658   if (UseAdaptiveGCBoundary) {
 659     if (size_policy()->bytes_absorbed_from_eden() != 0) {
 660       size_policy()->reset_bytes_absorbed_from_eden();
 661       return;  // The generation changed size already.
 662     }
 663     gens()->adjust_boundary_for_old_gen_needs(desired_free_space);
 664   }
 665 
 666   // Delegate the resize to the generation.
 667   _old_gen->resize(desired_free_space);
 668 }
 669 
 670 ParallelScavengeHeap::ParStrongRootsScope::ParStrongRootsScope() {
 671   // nothing particular
 672 }
 673 
 674 ParallelScavengeHeap::ParStrongRootsScope::~ParStrongRootsScope() {
 675   // nothing particular
 676 }
 677 
 678 #ifndef PRODUCT
 679 void ParallelScavengeHeap::record_gen_tops_before_GC() {
 680   if (ZapUnusedHeapArea) {
 681     young_gen()->record_spaces_top();
 682     old_gen()->record_spaces_top();
 683   }
 684 }
 685 
 686 void ParallelScavengeHeap::gen_mangle_unused_area() {
 687   if (ZapUnusedHeapArea) {
 688     young_gen()->eden_space()->mangle_unused_area();
 689     young_gen()->to_space()->mangle_unused_area();
 690     young_gen()->from_space()->mangle_unused_area();
 691     old_gen()->object_space()->mangle_unused_area();
 692   }
 693 }
 694 #endif
 695 
 696 bool ParallelScavengeHeap::is_scavengable(oop obj) {
 697   return is_in_young(obj);
 698 }
 699 
 700 void ParallelScavengeHeap::register_nmethod(nmethod* nm) {
 701   CodeCache::register_scavenge_root_nmethod(nm);
 702 }
 703 
 704 void ParallelScavengeHeap::verify_nmethod(nmethod* nm) {
 705   CodeCache::verify_scavenge_root_nmethod(nm);
 706 }
 707 
 708 GrowableArray<GCMemoryManager*> ParallelScavengeHeap::memory_managers() {
 709   GrowableArray<GCMemoryManager*> memory_managers(2);
 710   memory_managers.append(_young_manager);
 711   memory_managers.append(_old_manager);
 712   return memory_managers;
 713 }
 714 
 715 GrowableArray<MemoryPool*> ParallelScavengeHeap::memory_pools() {
 716   GrowableArray<MemoryPool*> memory_pools(3);
 717   memory_pools.append(_eden_pool);
 718   memory_pools.append(_survivor_pool);
 719   memory_pools.append(_old_pool);
 720   return memory_pools;
 721 }