1 /*
   2  * Copyright (c) 2001, 2016, 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.inline.hpp"
  29 #include "gc/shared/collectedHeap.hpp"
  30 #include "gc/shared/collectedHeap.inline.hpp"
  31 #include "gc/shared/gcHeapSummary.hpp"
  32 #include "gc/shared/gcTrace.hpp"
  33 #include "gc/shared/gcTraceTime.inline.hpp"
  34 #include "gc/shared/gcWhen.hpp"
  35 #include "gc/shared/vmGCOperations.hpp"
  36 #include "logging/log.hpp"
  37 #include "memory/metaspace.hpp"
  38 #include "memory/resourceArea.hpp"
  39 #include "oops/instanceMirrorKlass.hpp"
  40 #include "oops/oop.inline.hpp"
  41 #include "runtime/init.hpp"
  42 #include "runtime/thread.inline.hpp"
  43 #include "services/heapDumper.hpp"
  44 
  45 
  46 #ifdef ASSERT
  47 int CollectedHeap::_fire_out_of_memory_count = 0;
  48 #endif
  49 
  50 size_t CollectedHeap::_filler_array_max_size = 0;
  51 
  52 template <>
  53 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
  54   st->print_cr("GC heap %s", m.is_before ? "before" : "after");
  55   st->print_raw(m);
  56 }
  57 
  58 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
  59   if (!should_log()) {
  60     return;
  61   }
  62 
  63   double timestamp = fetch_timestamp();
  64   MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
  65   int index = compute_log_index();
  66   _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
  67   _records[index].timestamp = timestamp;
  68   _records[index].data.is_before = before;
  69   stringStream st(_records[index].data.buffer(), _records[index].data.size());
  70 
  71   st.print_cr("{Heap %s GC invocations=%u (full %u):",
  72                  before ? "before" : "after",
  73                  heap->total_collections(),
  74                  heap->total_full_collections());
  75 
  76   heap->print_on(&st);
  77   st.print_cr("}");
  78 }
  79 
  80 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
  81   size_t capacity_in_words = capacity() / HeapWordSize;
  82 
  83   return VirtualSpaceSummary(
  84     reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end());
  85 }
  86 
  87 GCHeapSummary CollectedHeap::create_heap_summary() {
  88   VirtualSpaceSummary heap_space = create_heap_space_summary();
  89   return GCHeapSummary(heap_space, used());
  90 }
  91 
  92 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
  93   const MetaspaceSizes meta_space(
  94       MetaspaceAux::committed_bytes(),
  95       MetaspaceAux::used_bytes(),
  96       MetaspaceAux::reserved_bytes());
  97   const MetaspaceSizes data_space(
  98       MetaspaceAux::committed_bytes(Metaspace::NonClassType),
  99       MetaspaceAux::used_bytes(Metaspace::NonClassType),
 100       MetaspaceAux::reserved_bytes(Metaspace::NonClassType));
 101   const MetaspaceSizes class_space(
 102       MetaspaceAux::committed_bytes(Metaspace::ClassType),
 103       MetaspaceAux::used_bytes(Metaspace::ClassType),
 104       MetaspaceAux::reserved_bytes(Metaspace::ClassType));
 105 
 106   const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
 107     MetaspaceAux::chunk_free_list_summary(Metaspace::NonClassType);
 108   const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
 109     MetaspaceAux::chunk_free_list_summary(Metaspace::ClassType);
 110 
 111   return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
 112                           ms_chunk_free_list_summary, class_chunk_free_list_summary);
 113 }
 114 
 115 void CollectedHeap::print_heap_before_gc() {
 116   Universe::print_heap_before_gc();
 117   if (_gc_heap_log != NULL) {
 118     _gc_heap_log->log_heap_before(this);
 119   }
 120 }
 121 
 122 void CollectedHeap::print_heap_after_gc() {
 123   Universe::print_heap_after_gc();
 124   if (_gc_heap_log != NULL) {
 125     _gc_heap_log->log_heap_after(this);
 126   }
 127 }
 128 
 129 void CollectedHeap::print_on_error(outputStream* st) const {
 130   st->print_cr("Heap:");
 131   print_extended_on(st);
 132   st->cr();
 133 
 134   _barrier_set->print_on(st);
 135 }
 136 
 137 void CollectedHeap::register_nmethod(nmethod* nm) {
 138   assert_locked_or_safepoint(CodeCache_lock);
 139 }
 140 
 141 void CollectedHeap::unregister_nmethod(nmethod* nm) {
 142   assert_locked_or_safepoint(CodeCache_lock);
 143 }
 144 
 145 void CollectedHeap::pin_object(oop o) {
 146   // Defaults to no-op
 147 }
 148 
 149 void CollectedHeap::unpin_object(oop o) {
 150   // Defaults to no-op
 151 }
 152 
 153 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
 154   const GCHeapSummary& heap_summary = create_heap_summary();
 155   gc_tracer->report_gc_heap_summary(when, heap_summary);
 156 
 157   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
 158   gc_tracer->report_metaspace_summary(when, metaspace_summary);
 159 }
 160 
 161 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
 162   trace_heap(GCWhen::BeforeGC, gc_tracer);
 163 }
 164 
 165 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
 166   trace_heap(GCWhen::AfterGC, gc_tracer);
 167 }
 168 
 169 // Memory state functions.
 170 
 171 
 172 CollectedHeap::CollectedHeap() :
 173   _barrier_set(NULL),
 174   _is_gc_active(false),
 175   _total_collections(0),
 176   _total_full_collections(0),
 177   _gc_cause(GCCause::_no_gc),
 178   _gc_lastcause(GCCause::_no_gc),
 179   _defer_initial_card_mark(false) // strengthened by subclass in pre_initialize() below.
 180 {
 181   const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
 182   const size_t elements_per_word = HeapWordSize / sizeof(jint);
 183   _filler_array_max_size = align_object_size(filler_array_hdr_size() +
 184                                              max_len / elements_per_word);
 185 
 186   NOT_PRODUCT(_promotion_failure_alot_count = 0;)
 187   NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
 188 
 189   if (UsePerfData) {
 190     EXCEPTION_MARK;
 191 
 192     // create the gc cause jvmstat counters
 193     _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
 194                              80, GCCause::to_string(_gc_cause), CHECK);
 195 
 196     _perf_gc_lastcause =
 197                 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
 198                              80, GCCause::to_string(_gc_lastcause), CHECK);
 199   }
 200 
 201   // Create the ring log
 202   if (LogEvents) {
 203     _gc_heap_log = new GCHeapLog();
 204   } else {
 205     _gc_heap_log = NULL;
 206   }
 207 }
 208 
 209 // This interface assumes that it's being called by the
 210 // vm thread. It collects the heap assuming that the
 211 // heap lock is already held and that we are executing in
 212 // the context of the vm thread.
 213 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
 214   assert(Thread::current()->is_VM_thread(), "Precondition#1");
 215   assert(Heap_lock->is_locked(), "Precondition#2");
 216   GCCauseSetter gcs(this, cause);
 217   switch (cause) {
 218     case GCCause::_heap_inspection:
 219     case GCCause::_heap_dump:
 220     case GCCause::_metadata_GC_threshold : {
 221       HandleMark hm;
 222       do_full_collection(false);        // don't clear all soft refs
 223       break;
 224     }
 225     case GCCause::_metadata_GC_clear_soft_refs: {
 226       HandleMark hm;
 227       do_full_collection(true);         // do clear all soft refs
 228       break;
 229     }
 230     default:
 231       ShouldNotReachHere(); // Unexpected use of this function
 232   }
 233 }
 234 
 235 void CollectedHeap::set_barrier_set(BarrierSet* barrier_set) {
 236   _barrier_set = barrier_set;
 237   oopDesc::set_bs(_barrier_set);
 238 }
 239 
 240 void CollectedHeap::pre_initialize() {
 241   // Used for ReduceInitialCardMarks (when COMPILER2 is used);
 242   // otherwise remains unused.
 243 #if defined(COMPILER2) || INCLUDE_JVMCI
 244   _defer_initial_card_mark = is_server_compilation_mode_vm() &&  ReduceInitialCardMarks && can_elide_tlab_store_barriers()
 245                              && (DeferInitialCardMark || card_mark_must_follow_store());
 246 #else
 247   assert(_defer_initial_card_mark == false, "Who would set it?");
 248 #endif
 249 }
 250 
 251 #ifndef PRODUCT
 252 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
 253   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 254     for (size_t slot = 0; slot < size; slot += 1) {
 255       assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
 256              "Found badHeapWordValue in post-allocation check");
 257     }
 258   }
 259 }
 260 
 261 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
 262   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 263     for (size_t slot = 0; slot < size; slot += 1) {
 264       assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
 265              "Found non badHeapWordValue in pre-allocation check");
 266     }
 267   }
 268 }
 269 #endif // PRODUCT
 270 
 271 #ifdef ASSERT
 272 void CollectedHeap::check_for_valid_allocation_state() {
 273   Thread *thread = Thread::current();
 274   // How to choose between a pending exception and a potential
 275   // OutOfMemoryError?  Don't allow pending exceptions.
 276   // This is a VM policy failure, so how do we exhaustively test it?
 277   assert(!thread->has_pending_exception(),
 278          "shouldn't be allocating with pending exception");
 279   if (StrictSafepointChecks) {
 280     assert(thread->allow_allocation(),
 281            "Allocation done by thread for which allocation is blocked "
 282            "by No_Allocation_Verifier!");
 283     // Allocation of an oop can always invoke a safepoint,
 284     // hence, the true argument
 285     thread->check_for_valid_safepoint_state(true);
 286   }
 287 }
 288 #endif
 289 
 290 HeapWord* CollectedHeap::allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size) {
 291 
 292   // Retain tlab and allocate object in shared space if
 293   // the amount free in the tlab is too large to discard.
 294   if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {
 295     thread->tlab().record_slow_allocation(size);
 296     return NULL;
 297   }
 298 
 299   // Discard tlab and allocate a new one.
 300   // To minimize fragmentation, the last TLAB may be smaller than the rest.
 301   size_t new_tlab_size = thread->tlab().compute_size(size);
 302 
 303   thread->tlab().clear_before_allocation();
 304 
 305   if (new_tlab_size == 0) {
 306     return NULL;
 307   }
 308 
 309   // Allocate a new TLAB...
 310   HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);
 311   if (obj == NULL) {
 312     return NULL;
 313   }
 314 
 315   AllocTracer::send_allocation_in_new_tlab_event(klass, new_tlab_size * HeapWordSize, size * HeapWordSize);
 316 
 317   if (ZeroTLAB) {
 318     // ..and clear it.
 319     Copy::zero_to_words(obj, new_tlab_size);
 320   } else {
 321     // ...and zap just allocated object.
 322 #ifdef ASSERT
 323     // Skip mangling the space corresponding to the object header to
 324     // ensure that the returned space is not considered parsable by
 325     // any concurrent GC thread.
 326     size_t hdr_size = oopDesc::header_size();
 327     Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal);
 328 #endif // ASSERT
 329   }
 330   thread->tlab().fill(obj, obj + size, new_tlab_size);
 331   return Universe::heap()->tlab_post_allocation_setup(obj);
 332 }
 333 
 334 void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
 335   MemRegion deferred = thread->deferred_card_mark();
 336   if (!deferred.is_empty()) {
 337     assert(_defer_initial_card_mark, "Otherwise should be empty");
 338     {
 339       // Verify that the storage points to a parsable object in heap
 340       DEBUG_ONLY(oop old_obj = oop(deferred.start());)
 341       assert(is_in(old_obj), "Not in allocated heap");
 342       assert(!can_elide_initializing_store_barrier(old_obj),
 343              "Else should have been filtered in new_store_pre_barrier()");
 344       assert(old_obj->is_oop(true), "Not an oop");
 345       assert(deferred.word_size() == (size_t)(old_obj->size()),
 346              "Mismatch: multiple objects?");
 347     }
 348     BarrierSet* bs = barrier_set();
 349     assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");
 350     bs->write_region(deferred);
 351     // "Clear" the deferred_card_mark field
 352     thread->set_deferred_card_mark(MemRegion());
 353   }
 354   assert(thread->deferred_card_mark().is_empty(), "invariant");
 355 }
 356 
 357 size_t CollectedHeap::max_tlab_size() const {
 358   // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
 359   // This restriction could be removed by enabling filling with multiple arrays.
 360   // If we compute that the reasonable way as
 361   //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
 362   // we'll overflow on the multiply, so we do the divide first.
 363   // We actually lose a little by dividing first,
 364   // but that just makes the TLAB  somewhat smaller than the biggest array,
 365   // which is fine, since we'll be able to fill that.
 366   size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
 367               sizeof(jint) *
 368               ((juint) max_jint / (size_t) HeapWordSize);
 369   return align_size_down(max_int_size, MinObjAlignment);
 370 }
 371 
 372 // Helper for ReduceInitialCardMarks. For performance,
 373 // compiled code may elide card-marks for initializing stores
 374 // to a newly allocated object along the fast-path. We
 375 // compensate for such elided card-marks as follows:
 376 // (a) Generational, non-concurrent collectors, such as
 377 //     GenCollectedHeap(ParNew,DefNew,Tenured) and
 378 //     ParallelScavengeHeap(ParallelGC, ParallelOldGC)
 379 //     need the card-mark if and only if the region is
 380 //     in the old gen, and do not care if the card-mark
 381 //     succeeds or precedes the initializing stores themselves,
 382 //     so long as the card-mark is completed before the next
 383 //     scavenge. For all these cases, we can do a card mark
 384 //     at the point at which we do a slow path allocation
 385 //     in the old gen, i.e. in this call.
 386 // (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
 387 //     in addition that the card-mark for an old gen allocated
 388 //     object strictly follow any associated initializing stores.
 389 //     In these cases, the memRegion remembered below is
 390 //     used to card-mark the entire region either just before the next
 391 //     slow-path allocation by this thread or just before the next scavenge or
 392 //     CMS-associated safepoint, whichever of these events happens first.
 393 //     (The implicit assumption is that the object has been fully
 394 //     initialized by this point, a fact that we assert when doing the
 395 //     card-mark.)
 396 // (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
 397 //     G1 concurrent marking is in progress an SATB (pre-write-)barrier
 398 //     is used to remember the pre-value of any store. Initializing
 399 //     stores will not need this barrier, so we need not worry about
 400 //     compensating for the missing pre-barrier here. Turning now
 401 //     to the post-barrier, we note that G1 needs a RS update barrier
 402 //     which simply enqueues a (sequence of) dirty cards which may
 403 //     optionally be refined by the concurrent update threads. Note
 404 //     that this barrier need only be applied to a non-young write,
 405 //     but, like in CMS, because of the presence of concurrent refinement
 406 //     (much like CMS' precleaning), must strictly follow the oop-store.
 407 //     Thus, using the same protocol for maintaining the intended
 408 //     invariants turns out, serendepitously, to be the same for both
 409 //     G1 and CMS.
 410 //
 411 // For any future collector, this code should be reexamined with
 412 // that specific collector in mind, and the documentation above suitably
 413 // extended and updated.
 414 oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
 415   // If a previous card-mark was deferred, flush it now.
 416   flush_deferred_store_barrier(thread);
 417   if (can_elide_initializing_store_barrier(new_obj) ||
 418       new_obj->is_typeArray()) {
 419     // Arrays of non-references don't need a pre-barrier.
 420     // The deferred_card_mark region should be empty
 421     // following the flush above.
 422     assert(thread->deferred_card_mark().is_empty(), "Error");
 423   } else {
 424     MemRegion mr((HeapWord*)new_obj, new_obj->size());
 425     assert(!mr.is_empty(), "Error");
 426     if (_defer_initial_card_mark) {
 427       // Defer the card mark
 428       thread->set_deferred_card_mark(mr);
 429     } else {
 430       // Do the card mark
 431       BarrierSet* bs = barrier_set();
 432       assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");
 433       bs->write_region(mr);
 434     }
 435   }
 436   return new_obj;
 437 }
 438 
 439 size_t CollectedHeap::filler_array_hdr_size() {
 440   return size_t(align_object_offset(arrayOopDesc::header_size(T_INT))); // align to Long
 441 }
 442 
 443 size_t CollectedHeap::filler_array_min_size() {
 444   return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
 445 }
 446 
 447 #ifdef ASSERT
 448 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
 449 {
 450   assert(words >= min_fill_size(), "too small to fill");
 451   assert(words % MinObjAlignment == 0, "unaligned size");
 452   assert(Universe::heap()->is_in_reserved(start), "not in heap");
 453   assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");
 454 }
 455 
 456 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
 457 {
 458   if (ZapFillerObjects && zap) {
 459     Copy::fill_to_words(start + filler_array_hdr_size(),
 460                         words - filler_array_hdr_size(), 0XDEAFBABE);
 461   }
 462 }
 463 #endif // ASSERT
 464 
 465 void
 466 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
 467 {
 468   assert(words >= filler_array_min_size(), "too small for an array");
 469   assert(words <= filler_array_max_size(), "too big for a single object");
 470 
 471   const size_t payload_size = words - filler_array_hdr_size();
 472   const size_t len = payload_size * HeapWordSize / sizeof(jint);
 473   assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
 474 
 475   // Set the length first for concurrent GC.
 476   ((arrayOop)start)->set_length((int)len);
 477   post_allocation_setup_common(Universe::intArrayKlassObj(), start);
 478   DEBUG_ONLY(zap_filler_array(start, words, zap);)
 479 }
 480 
 481 void
 482 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
 483 {
 484   assert(words <= filler_array_max_size(), "too big for a single object");
 485 
 486   if (words >= filler_array_min_size()) {
 487     fill_with_array(start, words, zap);
 488   } else if (words > 0) {
 489     assert(words == min_fill_size(), "unaligned size");
 490     post_allocation_setup_common(SystemDictionary::Object_klass(), start);
 491   }
 492 }
 493 
 494 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
 495 {
 496   DEBUG_ONLY(fill_args_check(start, words);)
 497   HandleMark hm;  // Free handles before leaving.
 498   fill_with_object_impl(start, words, zap);
 499 }
 500 
 501 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
 502 {
 503   DEBUG_ONLY(fill_args_check(start, words);)
 504   HandleMark hm;  // Free handles before leaving.
 505 
 506   // Multiple objects may be required depending on the filler array maximum size. Fill
 507   // the range up to that with objects that are filler_array_max_size sized. The
 508   // remainder is filled with a single object.
 509   const size_t min = min_fill_size();
 510   const size_t max = filler_array_max_size();
 511   while (words > max) {
 512     const size_t cur = (words - max) >= min ? max : max - min;
 513     fill_with_array(start, cur, zap);
 514     start += cur;
 515     words -= cur;
 516   }
 517 
 518   fill_with_object_impl(start, words, zap);
 519 }
 520 
 521 HeapWord* CollectedHeap::allocate_new_tlab(size_t size) {
 522   guarantee(false, "thread-local allocation buffers not supported");
 523   return NULL;
 524 }
 525 
 526 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
 527   // The second disjunct in the assertion below makes a concession
 528   // for the start-up verification done while the VM is being
 529   // created. Callers be careful that you know that mutators
 530   // aren't going to interfere -- for instance, this is permissible
 531   // if we are still single-threaded and have either not yet
 532   // started allocating (nothing much to verify) or we have
 533   // started allocating but are now a full-fledged JavaThread
 534   // (and have thus made our TLAB's) available for filling.
 535   assert(SafepointSynchronize::is_at_safepoint() ||
 536          !is_init_completed(),
 537          "Should only be called at a safepoint or at start-up"
 538          " otherwise concurrent mutator activity may make heap "
 539          " unparsable again");
 540   const bool use_tlab = UseTLAB;
 541   const bool deferred = _defer_initial_card_mark;
 542   // The main thread starts allocating via a TLAB even before it
 543   // has added itself to the threads list at vm boot-up.
 544   assert(!use_tlab || Threads::first() != NULL,
 545          "Attempt to fill tlabs before main thread has been added"
 546          " to threads list is doomed to failure!");
 547   for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
 548      if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
 549 #if defined(COMPILER2) || INCLUDE_JVMCI
 550      // The deferred store barriers must all have been flushed to the
 551      // card-table (or other remembered set structure) before GC starts
 552      // processing the card-table (or other remembered set).
 553      if (deferred) flush_deferred_store_barrier(thread);
 554 #else
 555      assert(!deferred, "Should be false");
 556      assert(thread->deferred_card_mark().is_empty(), "Should be empty");
 557 #endif
 558   }
 559 }
 560 
 561 void CollectedHeap::accumulate_statistics_all_tlabs() {
 562   if (UseTLAB) {
 563     assert(SafepointSynchronize::is_at_safepoint() ||
 564          !is_init_completed(),
 565          "should only accumulate statistics on tlabs at safepoint");
 566 
 567     ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
 568   }
 569 }
 570 
 571 void CollectedHeap::resize_all_tlabs() {
 572   if (UseTLAB) {
 573     assert(SafepointSynchronize::is_at_safepoint() ||
 574          !is_init_completed(),
 575          "should only resize tlabs at safepoint");
 576 
 577     ThreadLocalAllocBuffer::resize_all_tlabs();
 578   }
 579 }
 580 
 581 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
 582   assert(timer != NULL, "timer is null");
 583   if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
 584     GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
 585     HeapDumper::dump_heap();
 586   }
 587 
 588   Log(gc, classhisto) log;
 589   if (log.is_trace()) {
 590     GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
 591     ResourceMark rm;
 592     VM_GC_HeapInspection inspector(log.trace_stream(), false /* ! full gc */);
 593     inspector.doit();
 594   }
 595 }
 596 
 597 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
 598   full_gc_dump(timer, true);
 599 }
 600 
 601 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
 602   full_gc_dump(timer, false);
 603 }
 604 
 605 void CollectedHeap::initialize_reserved_region(HeapWord *start, HeapWord *end) {
 606   // It is important to do this in a way such that concurrent readers can't
 607   // temporarily think something is in the heap.  (Seen this happen in asserts.)
 608   _reserved.set_word_size(0);
 609   _reserved.set_start(start);
 610   _reserved.set_end(end);
 611 }
 612 HeapWord* CollectedHeap::tlab_post_allocation_setup(HeapWord* obj) {
 613   return obj;
 614 }
 615 
 616 uint CollectedHeap::oop_extra_words() {
 617   // Default implementation doesn't need extra space for oops.
 618   return 0;
 619 }
 620 
 621 void CollectedHeap::accumulate_statistics_all_gclabs() {
 622   // Default implementation does nothing.
 623 }
 624 
 625 void CollectedHeap::deflate_idle_monitors_all_threads() {
 626   ObjectSynchronizer::deflate_idle_monitors_all_threads();
 627 }
 628 
 629 class DeflateIdleMonitorsThreadClosure : public ThreadClosure {
 630 public:
 631   void do_thread(Thread* thread) {
 632     ObjectSynchronizer::deflate_idle_monitors_and_oops_do(thread, NULL);
 633   }
 634 };
 635 
 636 void CollectedHeap::parallel_deflate_idle_monitors(WorkGang* workers) {
 637   StrongRootsScope(workers->active_workers());
 638   DeflateIdleMonitorsThreadClosure cl;
 639   Threads::parallel_threads_do(&cl);
 640 }
 641 
 642 #ifndef CC_INTERP
 643 void CollectedHeap::compile_prepare_oop(MacroAssembler* masm, Register obj) {
 644   // Default implementation does nothing.
 645 }
 646 #endif