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 "classfile/systemDictionary.hpp"
  27 #include "gc/shared/allocTracer.hpp"
  28 #include "gc/shared/barrierSet.hpp"
  29 #include "gc/shared/collectedHeap.hpp"
  30 #include "gc/shared/collectedHeap.inline.hpp"
  31 #include "gc/shared/gcLocker.inline.hpp"
  32 #include "gc/shared/gcHeapSummary.hpp"
  33 #include "gc/shared/gcTrace.hpp"
  34 #include "gc/shared/gcTraceTime.inline.hpp"
  35 #include "gc/shared/gcWhen.hpp"
  36 #include "gc/shared/vmGCOperations.hpp"
  37 #include "logging/log.hpp"
  38 #include "memory/metaspace.hpp"
  39 #include "memory/resourceArea.hpp"
  40 #include "oops/instanceMirrorKlass.hpp"
  41 #include "oops/oop.inline.hpp"
  42 #include "runtime/handles.inline.hpp"
  43 #include "runtime/init.hpp"
  44 #include "runtime/thread.inline.hpp"
  45 #include "runtime/threadSMR.hpp"
  46 #include "runtime/vmThread.hpp"
  47 #include "services/heapDumper.hpp"
  48 #include "utilities/align.hpp"
  49 
  50 class ClassLoaderData;
  51 
  52 #ifdef ASSERT
  53 int CollectedHeap::_fire_out_of_memory_count = 0;
  54 #endif
  55 
  56 size_t CollectedHeap::_filler_array_max_size = 0;
  57 
  58 template <>
  59 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
  60   st->print_cr("GC heap %s", m.is_before ? "before" : "after");
  61   st->print_raw(m);
  62 }
  63 
  64 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
  65   if (!should_log()) {
  66     return;
  67   }
  68 
  69   double timestamp = fetch_timestamp();
  70   MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
  71   int index = compute_log_index();
  72   _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
  73   _records[index].timestamp = timestamp;
  74   _records[index].data.is_before = before;
  75   stringStream st(_records[index].data.buffer(), _records[index].data.size());
  76 
  77   st.print_cr("{Heap %s GC invocations=%u (full %u):",
  78                  before ? "before" : "after",
  79                  heap->total_collections(),
  80                  heap->total_full_collections());
  81 
  82   heap->print_on(&st);
  83   st.print_cr("}");
  84 }
  85 
  86 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
  87   size_t capacity_in_words = capacity() / HeapWordSize;
  88 
  89   return VirtualSpaceSummary(
  90     reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end());
  91 }
  92 
  93 GCHeapSummary CollectedHeap::create_heap_summary() {
  94   VirtualSpaceSummary heap_space = create_heap_space_summary();
  95   return GCHeapSummary(heap_space, used());
  96 }
  97 
  98 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
  99   const MetaspaceSizes meta_space(
 100       MetaspaceUtils::committed_bytes(),
 101       MetaspaceUtils::used_bytes(),
 102       MetaspaceUtils::reserved_bytes());
 103   const MetaspaceSizes data_space(
 104       MetaspaceUtils::committed_bytes(Metaspace::NonClassType),
 105       MetaspaceUtils::used_bytes(Metaspace::NonClassType),
 106       MetaspaceUtils::reserved_bytes(Metaspace::NonClassType));
 107   const MetaspaceSizes class_space(
 108       MetaspaceUtils::committed_bytes(Metaspace::ClassType),
 109       MetaspaceUtils::used_bytes(Metaspace::ClassType),
 110       MetaspaceUtils::reserved_bytes(Metaspace::ClassType));
 111 
 112   const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
 113     MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
 114   const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
 115     MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
 116 
 117   return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
 118                           ms_chunk_free_list_summary, class_chunk_free_list_summary);
 119 }
 120 
 121 void CollectedHeap::print_heap_before_gc() {
 122   Universe::print_heap_before_gc();
 123   if (_gc_heap_log != NULL) {
 124     _gc_heap_log->log_heap_before(this);
 125   }
 126 }
 127 
 128 void CollectedHeap::print_heap_after_gc() {
 129   Universe::print_heap_after_gc();
 130   if (_gc_heap_log != NULL) {
 131     _gc_heap_log->log_heap_after(this);
 132   }
 133 }
 134 
 135 void CollectedHeap::print_on_error(outputStream* st) const {
 136   st->print_cr("Heap:");
 137   print_extended_on(st);
 138   st->cr();
 139 
 140   BarrierSet::barrier_set()->print_on(st);
 141 }
 142 
 143 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
 144   const GCHeapSummary& heap_summary = create_heap_summary();
 145   gc_tracer->report_gc_heap_summary(when, heap_summary);
 146 
 147   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
 148   gc_tracer->report_metaspace_summary(when, metaspace_summary);
 149 }
 150 
 151 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
 152   trace_heap(GCWhen::BeforeGC, gc_tracer);
 153 }
 154 
 155 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
 156   trace_heap(GCWhen::AfterGC, gc_tracer);
 157 }
 158 
 159 // WhiteBox API support for concurrent collectors.  These are the
 160 // default implementations, for collectors which don't support this
 161 // feature.
 162 bool CollectedHeap::supports_concurrent_phase_control() const {
 163   return false;
 164 }
 165 
 166 const char* const* CollectedHeap::concurrent_phases() const {
 167   static const char* const result[] = { NULL };
 168   return result;
 169 }
 170 
 171 bool CollectedHeap::request_concurrent_phase(const char* phase) {
 172   return false;
 173 }
 174 
 175 // Memory state functions.
 176 
 177 
 178 CollectedHeap::CollectedHeap() :
 179   _is_gc_active(false),
 180   _total_collections(0),
 181   _total_full_collections(0),
 182   _gc_cause(GCCause::_no_gc),
 183   _gc_lastcause(GCCause::_no_gc)
 184 {
 185   const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
 186   const size_t elements_per_word = HeapWordSize / sizeof(jint);
 187   _filler_array_max_size = align_object_size(filler_array_hdr_size() +
 188                                              max_len / elements_per_word);
 189 
 190   NOT_PRODUCT(_promotion_failure_alot_count = 0;)
 191   NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
 192 
 193   if (UsePerfData) {
 194     EXCEPTION_MARK;
 195 
 196     // create the gc cause jvmstat counters
 197     _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
 198                              80, GCCause::to_string(_gc_cause), CHECK);
 199 
 200     _perf_gc_lastcause =
 201                 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
 202                              80, GCCause::to_string(_gc_lastcause), CHECK);
 203   }
 204 
 205   // Create the ring log
 206   if (LogEvents) {
 207     _gc_heap_log = new GCHeapLog();
 208   } else {
 209     _gc_heap_log = NULL;
 210   }
 211 }
 212 
 213 // This interface assumes that it's being called by the
 214 // vm thread. It collects the heap assuming that the
 215 // heap lock is already held and that we are executing in
 216 // the context of the vm thread.
 217 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
 218   assert(Thread::current()->is_VM_thread(), "Precondition#1");
 219   assert(Heap_lock->is_locked(), "Precondition#2");
 220   GCCauseSetter gcs(this, cause);
 221   switch (cause) {
 222     case GCCause::_heap_inspection:
 223     case GCCause::_heap_dump:
 224     case GCCause::_metadata_GC_threshold : {
 225       HandleMark hm;
 226       do_full_collection(false);        // don't clear all soft refs
 227       break;
 228     }
 229     case GCCause::_metadata_GC_clear_soft_refs: {
 230       HandleMark hm;
 231       do_full_collection(true);         // do clear all soft refs
 232       break;
 233     }
 234     default:
 235       ShouldNotReachHere(); // Unexpected use of this function
 236   }
 237 }
 238 
 239 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 240                                                             size_t word_size,
 241                                                             Metaspace::MetadataType mdtype) {
 242   uint loop_count = 0;
 243   uint gc_count = 0;
 244   uint full_gc_count = 0;
 245 
 246   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
 247 
 248   do {
 249     MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
 250     if (result != NULL) {
 251       return result;
 252     }
 253 
 254     if (GCLocker::is_active_and_needs_gc()) {
 255       // If the GCLocker is active, just expand and allocate.
 256       // If that does not succeed, wait if this thread is not
 257       // in a critical section itself.
 258       result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
 259       if (result != NULL) {
 260         return result;
 261       }
 262       JavaThread* jthr = JavaThread::current();
 263       if (!jthr->in_critical()) {
 264         // Wait for JNI critical section to be exited
 265         GCLocker::stall_until_clear();
 266         // The GC invoked by the last thread leaving the critical
 267         // section will be a young collection and a full collection
 268         // is (currently) needed for unloading classes so continue
 269         // to the next iteration to get a full GC.
 270         continue;
 271       } else {
 272         if (CheckJNICalls) {
 273           fatal("Possible deadlock due to allocating while"
 274                 " in jni critical section");
 275         }
 276         return NULL;
 277       }
 278     }
 279 
 280     {  // Need lock to get self consistent gc_count's
 281       MutexLocker ml(Heap_lock);
 282       gc_count      = Universe::heap()->total_collections();
 283       full_gc_count = Universe::heap()->total_full_collections();
 284     }
 285 
 286     // Generate a VM operation
 287     VM_CollectForMetadataAllocation op(loader_data,
 288                                        word_size,
 289                                        mdtype,
 290                                        gc_count,
 291                                        full_gc_count,
 292                                        GCCause::_metadata_GC_threshold);
 293     VMThread::execute(&op);
 294 
 295     // If GC was locked out, try again. Check before checking success because the
 296     // prologue could have succeeded and the GC still have been locked out.
 297     if (op.gc_locked()) {
 298       continue;
 299     }
 300 
 301     if (op.prologue_succeeded()) {
 302       return op.result();
 303     }
 304     loop_count++;
 305     if ((QueuedAllocationWarningCount > 0) &&
 306         (loop_count % QueuedAllocationWarningCount == 0)) {
 307       log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
 308                             " size=" SIZE_FORMAT, loop_count, word_size);
 309     }
 310   } while (true);  // Until a GC is done
 311 }
 312 
 313 #ifndef PRODUCT
 314 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
 315   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 316     for (size_t slot = 0; slot < size; slot += 1) {
 317       assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
 318              "Found badHeapWordValue in post-allocation check");
 319     }
 320   }
 321 }
 322 
 323 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
 324   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 325     for (size_t slot = 0; slot < size; slot += 1) {
 326       assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
 327              "Found non badHeapWordValue in pre-allocation check");
 328     }
 329   }
 330 }
 331 #endif // PRODUCT
 332 
 333 #ifdef ASSERT
 334 void CollectedHeap::check_for_valid_allocation_state() {
 335   Thread *thread = Thread::current();
 336   // How to choose between a pending exception and a potential
 337   // OutOfMemoryError?  Don't allow pending exceptions.
 338   // This is a VM policy failure, so how do we exhaustively test it?
 339   assert(!thread->has_pending_exception(),
 340          "shouldn't be allocating with pending exception");
 341   if (StrictSafepointChecks) {
 342     assert(thread->allow_allocation(),
 343            "Allocation done by thread for which allocation is blocked "
 344            "by No_Allocation_Verifier!");
 345     // Allocation of an oop can always invoke a safepoint,
 346     // hence, the true argument
 347     thread->check_for_valid_safepoint_state(true);
 348   }
 349 }
 350 #endif
 351 
 352 HeapWord* CollectedHeap::allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size) {
 353 
 354   // Retain tlab and allocate object in shared space if
 355   // the amount free in the tlab is too large to discard.
 356   if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {
 357     thread->tlab().record_slow_allocation(size);
 358     return NULL;
 359   }
 360 
 361   // Discard tlab and allocate a new one.
 362   // To minimize fragmentation, the last TLAB may be smaller than the rest.
 363   size_t new_tlab_size = thread->tlab().compute_size(size);
 364 
 365   thread->tlab().clear_before_allocation();
 366 
 367   if (new_tlab_size == 0) {
 368     return NULL;
 369   }
 370 
 371   // Allocate a new TLAB...
 372   HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);
 373   if (obj == NULL) {
 374     return NULL;
 375   }
 376 
 377   AllocTracer::send_allocation_in_new_tlab(klass, obj, new_tlab_size * HeapWordSize, size * HeapWordSize, thread);
 378 
 379   if (ZeroTLAB) {
 380     // ..and clear it.
 381     Copy::zero_to_words(obj, new_tlab_size);
 382   } else {
 383     // ...and zap just allocated object.
 384 #ifdef ASSERT
 385     // Skip mangling the space corresponding to the object header to
 386     // ensure that the returned space is not considered parsable by
 387     // any concurrent GC thread.
 388     size_t hdr_size = oopDesc::header_size();
 389     Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal);
 390 #endif // ASSERT
 391   }
 392   thread->tlab().fill(obj, obj + size, new_tlab_size);
 393   return Universe::heap()->tlab_post_allocation_setup(obj);
 394 }
 395 
 396 size_t CollectedHeap::max_tlab_size() const {
 397   // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
 398   // This restriction could be removed by enabling filling with multiple arrays.
 399   // If we compute that the reasonable way as
 400   //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
 401   // we'll overflow on the multiply, so we do the divide first.
 402   // We actually lose a little by dividing first,
 403   // but that just makes the TLAB  somewhat smaller than the biggest array,
 404   // which is fine, since we'll be able to fill that.
 405   size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
 406               sizeof(jint) *
 407               ((juint) max_jint / (size_t) HeapWordSize);
 408   return align_down(max_int_size, MinObjAlignment);
 409 }
 410 
 411 size_t CollectedHeap::filler_array_hdr_size() {
 412   return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
 413 }
 414 
 415 size_t CollectedHeap::filler_array_min_size() {
 416   return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
 417 }
 418 
 419 #ifdef ASSERT
 420 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
 421 {
 422   assert(words >= min_fill_size(), "too small to fill");
 423   assert(is_object_aligned(words), "unaligned size");
 424   assert(Universe::heap()->is_in_reserved(start), "not in heap");
 425   assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");
 426 }
 427 
 428 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
 429 {
 430   if (ZapFillerObjects && zap) {
 431     Copy::fill_to_words(start + filler_array_hdr_size(),
 432                         words - filler_array_hdr_size(), 0XDEAFBABE);
 433   }
 434 }
 435 #endif // ASSERT
 436 
 437 void
 438 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
 439 {
 440   assert(words >= filler_array_min_size(), "too small for an array");
 441   assert(words <= filler_array_max_size(), "too big for a single object");
 442 
 443   const size_t payload_size = words - filler_array_hdr_size();
 444   const size_t len = payload_size * HeapWordSize / sizeof(jint);
 445   assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
 446 
 447   // Set the length first for concurrent GC.
 448   ((arrayOop)start)->set_length((int)len);
 449   post_allocation_setup_common(Universe::intArrayKlassObj(), start);
 450   DEBUG_ONLY(zap_filler_array(start, words, zap);)
 451 }
 452 
 453 void
 454 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
 455 {
 456   assert(words <= filler_array_max_size(), "too big for a single object");
 457 
 458   if (words >= filler_array_min_size()) {
 459     fill_with_array(start, words, zap);
 460   } else if (words > 0) {
 461     assert(words == min_fill_size(), "unaligned size");
 462     post_allocation_setup_common(SystemDictionary::Object_klass(), start);
 463   }
 464 }
 465 
 466 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
 467 {
 468   DEBUG_ONLY(fill_args_check(start, words);)
 469   HandleMark hm;  // Free handles before leaving.
 470   fill_with_object_impl(start, words, zap);
 471 }
 472 
 473 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
 474 {
 475   DEBUG_ONLY(fill_args_check(start, words);)
 476   HandleMark hm;  // Free handles before leaving.
 477 
 478   // Multiple objects may be required depending on the filler array maximum size. Fill
 479   // the range up to that with objects that are filler_array_max_size sized. The
 480   // remainder is filled with a single object.
 481   const size_t min = min_fill_size();
 482   const size_t max = filler_array_max_size();
 483   while (words > max) {
 484     const size_t cur = (words - max) >= min ? max : max - min;
 485     fill_with_array(start, cur, zap);
 486     start += cur;
 487     words -= cur;
 488   }
 489 
 490   fill_with_object_impl(start, words, zap);
 491 }
 492 
 493 HeapWord* CollectedHeap::allocate_new_tlab(size_t size) {
 494   guarantee(false, "thread-local allocation buffers not supported");
 495   return NULL;
 496 }
 497 
 498 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
 499   // The second disjunct in the assertion below makes a concession
 500   // for the start-up verification done while the VM is being
 501   // created. Callers be careful that you know that mutators
 502   // aren't going to interfere -- for instance, this is permissible
 503   // if we are still single-threaded and have either not yet
 504   // started allocating (nothing much to verify) or we have
 505   // started allocating but are now a full-fledged JavaThread
 506   // (and have thus made our TLAB's) available for filling.
 507   assert(SafepointSynchronize::is_at_safepoint() ||
 508          !is_init_completed(),
 509          "Should only be called at a safepoint or at start-up"
 510          " otherwise concurrent mutator activity may make heap "
 511          " unparsable again");
 512   const bool use_tlab = UseTLAB;
 513   // The main thread starts allocating via a TLAB even before it
 514   // has added itself to the threads list at vm boot-up.
 515   JavaThreadIteratorWithHandle jtiwh;
 516   assert(!use_tlab || jtiwh.length() > 0,
 517          "Attempt to fill tlabs before main thread has been added"
 518          " to threads list is doomed to failure!");
 519   BarrierSet *bs = BarrierSet::barrier_set();
 520   for (; JavaThread *thread = jtiwh.next(); ) {
 521      if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
 522      bs->make_parsable(thread);
 523   }
 524 }
 525 
 526 void CollectedHeap::accumulate_statistics_all_tlabs() {
 527   if (UseTLAB) {
 528     assert(SafepointSynchronize::is_at_safepoint() ||
 529          !is_init_completed(),
 530          "should only accumulate statistics on tlabs at safepoint");
 531 
 532     ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
 533   }
 534 }
 535 
 536 void CollectedHeap::resize_all_tlabs() {
 537   if (UseTLAB) {
 538     assert(SafepointSynchronize::is_at_safepoint() ||
 539          !is_init_completed(),
 540          "should only resize tlabs at safepoint");
 541 
 542     ThreadLocalAllocBuffer::resize_all_tlabs();
 543   }
 544 }
 545 
 546 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
 547   assert(timer != NULL, "timer is null");
 548   if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
 549     GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
 550     HeapDumper::dump_heap();
 551   }
 552 
 553   LogTarget(Trace, gc, classhisto) lt;
 554   if (lt.is_enabled()) {
 555     GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
 556     ResourceMark rm;
 557     LogStream ls(lt);
 558     VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
 559     inspector.doit();
 560   }
 561 }
 562 
 563 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
 564   full_gc_dump(timer, true);
 565 }
 566 
 567 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
 568   full_gc_dump(timer, false);
 569 }
 570 
 571 void CollectedHeap::initialize_reserved_region(HeapWord *start, HeapWord *end) {
 572   // It is important to do this in a way such that concurrent readers can't
 573   // temporarily think something is in the heap.  (Seen this happen in asserts.)
 574   _reserved.set_word_size(0);
 575   _reserved.set_start(start);
 576   _reserved.set_end(end);
 577 }
 578 
 579 void CollectedHeap::post_initialize() {
 580   initialize_serviceability();
 581 }
 582 
 583 #ifndef PRODUCT
 584 
 585 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
 586   // Access to count is not atomic; the value does not have to be exact.
 587   if (PromotionFailureALot) {
 588     const size_t gc_num = total_collections();
 589     const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
 590     if (elapsed_gcs >= PromotionFailureALotInterval) {
 591       // Test for unsigned arithmetic wrap-around.
 592       if (++*count >= PromotionFailureALotCount) {
 593         *count = 0;
 594         return true;
 595       }
 596     }
 597   }
 598   return false;
 599 }
 600 
 601 bool CollectedHeap::promotion_should_fail() {
 602   return promotion_should_fail(&_promotion_failure_alot_count);
 603 }
 604 
 605 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
 606   if (PromotionFailureALot) {
 607     _promotion_failure_alot_gc_number = total_collections();
 608     *count = 0;
 609   }
 610 }
 611 
 612 void CollectedHeap::reset_promotion_should_fail() {
 613   reset_promotion_should_fail(&_promotion_failure_alot_count);
 614 }
 615 
 616 #endif  // #ifndef PRODUCT
 617 
 618 bool CollectedHeap::supports_object_pinning() const {
 619   return false;
 620 }
 621 
 622 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
 623   ShouldNotReachHere();
 624   return NULL;
 625 }
 626 
 627 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
 628   ShouldNotReachHere();
 629 }
 630 
 631 HeapWord* CollectedHeap::tlab_post_allocation_setup(HeapWord* obj) {
 632   return obj;
 633 }
 634 
 635 uint CollectedHeap::oop_extra_words() {
 636   // Default implementation doesn't need extra space for oops.
 637   return 0;
 638 }
 639 
 640 void CollectedHeap::accumulate_statistics_all_gclabs() {
 641   // Default implementation does nothing.
 642 }
 643 
 644 #ifndef CC_INTERP
 645 void CollectedHeap::compile_prepare_oop(MacroAssembler* masm, Register obj) {
 646   // Default implementation does nothing.
 647 }
 648 #endif