1 /*
   2  * Copyright (c) 2001, 2017, 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 "runtime/threadSMR.hpp"
  44 #include "services/heapDumper.hpp"
  45 #include "utilities/align.hpp"
  46 
  47 
  48 #ifdef ASSERT
  49 int CollectedHeap::_fire_out_of_memory_count = 0;
  50 #endif
  51 
  52 size_t CollectedHeap::_filler_array_max_size = 0;
  53 
  54 template <>
  55 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
  56   st->print_cr("GC heap %s", m.is_before ? "before" : "after");
  57   st->print_raw(m);
  58 }
  59 
  60 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
  61   if (!should_log()) {
  62     return;
  63   }
  64 
  65   double timestamp = fetch_timestamp();
  66   MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
  67   int index = compute_log_index();
  68   _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
  69   _records[index].timestamp = timestamp;
  70   _records[index].data.is_before = before;
  71   stringStream st(_records[index].data.buffer(), _records[index].data.size());
  72 
  73   st.print_cr("{Heap %s GC invocations=%u (full %u):",
  74                  before ? "before" : "after",
  75                  heap->total_collections(),
  76                  heap->total_full_collections());
  77 
  78   heap->print_on(&st);
  79   st.print_cr("}");
  80 }
  81 
  82 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
  83   size_t capacity_in_words = capacity() / HeapWordSize;
  84 
  85   return VirtualSpaceSummary(
  86     reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end());
  87 }
  88 
  89 GCHeapSummary CollectedHeap::create_heap_summary() {
  90   VirtualSpaceSummary heap_space = create_heap_space_summary();
  91   return GCHeapSummary(heap_space, used());
  92 }
  93 
  94 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
  95   const MetaspaceSizes meta_space(
  96       MetaspaceAux::committed_bytes(),
  97       MetaspaceAux::used_bytes(),
  98       MetaspaceAux::reserved_bytes());
  99   const MetaspaceSizes data_space(
 100       MetaspaceAux::committed_bytes(Metaspace::NonClassType),
 101       MetaspaceAux::used_bytes(Metaspace::NonClassType),
 102       MetaspaceAux::reserved_bytes(Metaspace::NonClassType));
 103   const MetaspaceSizes class_space(
 104       MetaspaceAux::committed_bytes(Metaspace::ClassType),
 105       MetaspaceAux::used_bytes(Metaspace::ClassType),
 106       MetaspaceAux::reserved_bytes(Metaspace::ClassType));
 107 
 108   const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
 109     MetaspaceAux::chunk_free_list_summary(Metaspace::NonClassType);
 110   const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
 111     MetaspaceAux::chunk_free_list_summary(Metaspace::ClassType);
 112 
 113   return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
 114                           ms_chunk_free_list_summary, class_chunk_free_list_summary);
 115 }
 116 
 117 void CollectedHeap::print_heap_before_gc() {
 118   Universe::print_heap_before_gc();
 119   if (_gc_heap_log != NULL) {
 120     _gc_heap_log->log_heap_before(this);
 121   }
 122 }
 123 
 124 void CollectedHeap::print_heap_after_gc() {
 125   Universe::print_heap_after_gc();
 126   if (_gc_heap_log != NULL) {
 127     _gc_heap_log->log_heap_after(this);
 128   }
 129 }
 130 
 131 void CollectedHeap::print_on_error(outputStream* st) const {
 132   st->print_cr("Heap:");
 133   print_extended_on(st);
 134   st->cr();
 135 
 136   _barrier_set->print_on(st);
 137 }
 138 
 139 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
 140   const GCHeapSummary& heap_summary = create_heap_summary();
 141   gc_tracer->report_gc_heap_summary(when, heap_summary);
 142 
 143   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
 144   gc_tracer->report_metaspace_summary(when, metaspace_summary);
 145 }
 146 
 147 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
 148   trace_heap(GCWhen::BeforeGC, gc_tracer);
 149 }
 150 
 151 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
 152   trace_heap(GCWhen::AfterGC, gc_tracer);
 153 }
 154 
 155 // WhiteBox API support for concurrent collectors.  These are the
 156 // default implementations, for collectors which don't support this
 157 // feature.
 158 bool CollectedHeap::supports_concurrent_phase_control() const {
 159   return false;
 160 }
 161 
 162 const char* const* CollectedHeap::concurrent_phases() const {
 163   static const char* const result[] = { NULL };
 164   return result;
 165 }
 166 
 167 bool CollectedHeap::request_concurrent_phase(const char* phase) {
 168   return false;
 169 }
 170 
 171 // Memory state functions.
 172 
 173 
 174 CollectedHeap::CollectedHeap() :
 175   _barrier_set(NULL),
 176   _is_gc_active(false),
 177   _total_collections(0),
 178   _total_full_collections(0),
 179   _gc_cause(GCCause::_no_gc),
 180   _gc_lastcause(GCCause::_no_gc),
 181   _defer_initial_card_mark(false) // strengthened by subclass in pre_initialize() below.
 182 {
 183   const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
 184   const size_t elements_per_word = HeapWordSize / sizeof(jint);
 185   _filler_array_max_size = align_object_size(filler_array_hdr_size() +
 186                                              max_len / elements_per_word);
 187 
 188   NOT_PRODUCT(_promotion_failure_alot_count = 0;)
 189   NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
 190 
 191   if (UsePerfData) {
 192     EXCEPTION_MARK;
 193 
 194     // create the gc cause jvmstat counters
 195     _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
 196                              80, GCCause::to_string(_gc_cause), CHECK);
 197 
 198     _perf_gc_lastcause =
 199                 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
 200                              80, GCCause::to_string(_gc_lastcause), CHECK);
 201   }
 202 
 203   // Create the ring log
 204   if (LogEvents) {
 205     _gc_heap_log = new GCHeapLog();
 206   } else {
 207     _gc_heap_log = NULL;
 208   }
 209 }
 210 
 211 // This interface assumes that it's being called by the
 212 // vm thread. It collects the heap assuming that the
 213 // heap lock is already held and that we are executing in
 214 // the context of the vm thread.
 215 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
 216   assert(Thread::current()->is_VM_thread(), "Precondition#1");
 217   assert(Heap_lock->is_locked(), "Precondition#2");
 218   GCCauseSetter gcs(this, cause);
 219   switch (cause) {
 220     case GCCause::_heap_inspection:
 221     case GCCause::_heap_dump:
 222     case GCCause::_metadata_GC_threshold : {
 223       HandleMark hm;
 224       do_full_collection(false);        // don't clear all soft refs
 225       break;
 226     }
 227     case GCCause::_metadata_GC_clear_soft_refs: {
 228       HandleMark hm;
 229       do_full_collection(true);         // do clear all soft refs
 230       break;
 231     }
 232     default:
 233       ShouldNotReachHere(); // Unexpected use of this function
 234   }
 235 }
 236 
 237 void CollectedHeap::set_barrier_set(BarrierSet* barrier_set) {
 238   _barrier_set = barrier_set;
 239   oopDesc::set_bs(_barrier_set);
 240 }
 241 
 242 void CollectedHeap::pre_initialize() {
 243   // Used for ReduceInitialCardMarks (when COMPILER2 is used);
 244   // otherwise remains unused.
 245 #if COMPILER2_OR_JVMCI
 246   _defer_initial_card_mark = is_server_compilation_mode_vm() &&  ReduceInitialCardMarks && can_elide_tlab_store_barriers()
 247                              && (DeferInitialCardMark || card_mark_must_follow_store());
 248 #else
 249   assert(_defer_initial_card_mark == false, "Who would set it?");
 250 #endif
 251 }
 252 
 253 #ifndef PRODUCT
 254 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
 255   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 256     for (size_t slot = 0; slot < size; slot += 1) {
 257       assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
 258              "Found badHeapWordValue in post-allocation check");
 259     }
 260   }
 261 }
 262 
 263 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
 264   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 265     for (size_t slot = 0; slot < size; slot += 1) {
 266       assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
 267              "Found non badHeapWordValue in pre-allocation check");
 268     }
 269   }
 270 }
 271 #endif // PRODUCT
 272 
 273 #ifdef ASSERT
 274 void CollectedHeap::check_for_valid_allocation_state() {
 275   Thread *thread = Thread::current();
 276   // How to choose between a pending exception and a potential
 277   // OutOfMemoryError?  Don't allow pending exceptions.
 278   // This is a VM policy failure, so how do we exhaustively test it?
 279   assert(!thread->has_pending_exception(),
 280          "shouldn't be allocating with pending exception");
 281   if (StrictSafepointChecks) {
 282     assert(thread->allow_allocation(),
 283            "Allocation done by thread for which allocation is blocked "
 284            "by No_Allocation_Verifier!");
 285     // Allocation of an oop can always invoke a safepoint,
 286     // hence, the true argument
 287     thread->check_for_valid_safepoint_state(true);
 288   }
 289 }
 290 #endif
 291 
 292 HeapWord* CollectedHeap::allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size) {
 293 
 294   // Retain tlab and allocate object in shared space if
 295   // the amount free in the tlab is too large to discard.
 296   if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {
 297     thread->tlab().record_slow_allocation(size);
 298     return NULL;
 299   }
 300 
 301   // Discard tlab and allocate a new one.
 302   // To minimize fragmentation, the last TLAB may be smaller than the rest.
 303   size_t new_tlab_size = thread->tlab().compute_size(size);
 304 
 305   thread->tlab().clear_before_allocation();
 306 
 307   if (new_tlab_size == 0) {
 308     return NULL;
 309   }
 310 
 311   // Allocate a new TLAB...
 312   HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);
 313   if (obj == NULL) {
 314     return NULL;
 315   }
 316 
 317   AllocTracer::send_allocation_in_new_tlab(klass, obj, new_tlab_size * HeapWordSize, size * HeapWordSize, thread);
 318 
 319   if (ZeroTLAB) {
 320     // ..and clear it.
 321     Copy::zero_to_words(obj, new_tlab_size);
 322   } else {
 323     // ...and zap just allocated object.
 324 #ifdef ASSERT
 325     // Skip mangling the space corresponding to the object header to
 326     // ensure that the returned space is not considered parsable by
 327     // any concurrent GC thread.
 328     size_t hdr_size = oopDesc::header_size();
 329     Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal);
 330 #endif // ASSERT
 331   }
 332   thread->tlab().fill(obj, obj + size, new_tlab_size);
 333   return obj;
 334 }
 335 
 336 void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
 337   MemRegion deferred = thread->deferred_card_mark();
 338   if (!deferred.is_empty()) {
 339     assert(_defer_initial_card_mark, "Otherwise should be empty");
 340     {
 341       // Verify that the storage points to a parsable object in heap
 342       DEBUG_ONLY(oop old_obj = oop(deferred.start());)
 343       assert(is_in(old_obj), "Not in allocated heap");
 344       assert(!can_elide_initializing_store_barrier(old_obj),
 345              "Else should have been filtered in new_store_pre_barrier()");
 346       assert(oopDesc::is_oop(old_obj, true), "Not an oop");
 347       assert(deferred.word_size() == (size_t)(old_obj->size()),
 348              "Mismatch: multiple objects?");
 349     }
 350     BarrierSet* bs = barrier_set();
 351     bs->write_region(deferred);
 352     // "Clear" the deferred_card_mark field
 353     thread->set_deferred_card_mark(MemRegion());
 354   }
 355   assert(thread->deferred_card_mark().is_empty(), "invariant");
 356 }
 357 
 358 size_t CollectedHeap::max_tlab_size() const {
 359   // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
 360   // This restriction could be removed by enabling filling with multiple arrays.
 361   // If we compute that the reasonable way as
 362   //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
 363   // we'll overflow on the multiply, so we do the divide first.
 364   // We actually lose a little by dividing first,
 365   // but that just makes the TLAB  somewhat smaller than the biggest array,
 366   // which is fine, since we'll be able to fill that.
 367   size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
 368               sizeof(jint) *
 369               ((juint) max_jint / (size_t) HeapWordSize);
 370   return align_down(max_int_size, MinObjAlignment);
 371 }
 372 
 373 // Helper for ReduceInitialCardMarks. For performance,
 374 // compiled code may elide card-marks for initializing stores
 375 // to a newly allocated object along the fast-path. We
 376 // compensate for such elided card-marks as follows:
 377 // (a) Generational, non-concurrent collectors, such as
 378 //     GenCollectedHeap(ParNew,DefNew,Tenured) and
 379 //     ParallelScavengeHeap(ParallelGC, ParallelOldGC)
 380 //     need the card-mark if and only if the region is
 381 //     in the old gen, and do not care if the card-mark
 382 //     succeeds or precedes the initializing stores themselves,
 383 //     so long as the card-mark is completed before the next
 384 //     scavenge. For all these cases, we can do a card mark
 385 //     at the point at which we do a slow path allocation
 386 //     in the old gen, i.e. in this call.
 387 // (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
 388 //     in addition that the card-mark for an old gen allocated
 389 //     object strictly follow any associated initializing stores.
 390 //     In these cases, the memRegion remembered below is
 391 //     used to card-mark the entire region either just before the next
 392 //     slow-path allocation by this thread or just before the next scavenge or
 393 //     CMS-associated safepoint, whichever of these events happens first.
 394 //     (The implicit assumption is that the object has been fully
 395 //     initialized by this point, a fact that we assert when doing the
 396 //     card-mark.)
 397 // (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
 398 //     G1 concurrent marking is in progress an SATB (pre-write-)barrier
 399 //     is used to remember the pre-value of any store. Initializing
 400 //     stores will not need this barrier, so we need not worry about
 401 //     compensating for the missing pre-barrier here. Turning now
 402 //     to the post-barrier, we note that G1 needs a RS update barrier
 403 //     which simply enqueues a (sequence of) dirty cards which may
 404 //     optionally be refined by the concurrent update threads. Note
 405 //     that this barrier need only be applied to a non-young write,
 406 //     but, like in CMS, because of the presence of concurrent refinement
 407 //     (much like CMS' precleaning), must strictly follow the oop-store.
 408 //     Thus, using the same protocol for maintaining the intended
 409 //     invariants turns out, serendepitously, to be the same for both
 410 //     G1 and CMS.
 411 //
 412 // For any future collector, this code should be reexamined with
 413 // that specific collector in mind, and the documentation above suitably
 414 // extended and updated.
 415 oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
 416   // If a previous card-mark was deferred, flush it now.
 417   flush_deferred_store_barrier(thread);
 418   if (can_elide_initializing_store_barrier(new_obj) ||
 419       new_obj->is_typeArray()) {
 420     // Arrays of non-references don't need a pre-barrier.
 421     // The deferred_card_mark region should be empty
 422     // following the flush above.
 423     assert(thread->deferred_card_mark().is_empty(), "Error");
 424   } else {
 425     MemRegion mr((HeapWord*)new_obj, new_obj->size());
 426     assert(!mr.is_empty(), "Error");
 427     if (_defer_initial_card_mark) {
 428       // Defer the card mark
 429       thread->set_deferred_card_mark(mr);
 430     } else {
 431       // Do the card mark
 432       BarrierSet* bs = barrier_set();
 433       bs->write_region(mr);
 434     }
 435   }
 436   return new_obj;
 437 }
 438 
 439 size_t CollectedHeap::filler_array_hdr_size() {
 440   return 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(is_object_aligned(words), "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   JavaThreadIteratorWithHandle jtiwh;
 545   assert(!use_tlab || jtiwh.length() > 0,
 546          "Attempt to fill tlabs before main thread has been added"
 547          " to threads list is doomed to failure!");
 548   for (; JavaThread *thread = jtiwh.next(); ) {
 549      if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
 550 #if COMPILER2_OR_JVMCI
 551      // The deferred store barriers must all have been flushed to the
 552      // card-table (or other remembered set structure) before GC starts
 553      // processing the card-table (or other remembered set).
 554      if (deferred) flush_deferred_store_barrier(thread);
 555 #else
 556      assert(!deferred, "Should be false");
 557      assert(thread->deferred_card_mark().is_empty(), "Should be empty");
 558 #endif
 559   }
 560 }
 561 
 562 void CollectedHeap::accumulate_statistics_all_tlabs() {
 563   if (UseTLAB) {
 564     assert(SafepointSynchronize::is_at_safepoint() ||
 565          !is_init_completed(),
 566          "should only accumulate statistics on tlabs at safepoint");
 567 
 568     ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
 569   }
 570 }
 571 
 572 void CollectedHeap::resize_all_tlabs() {
 573   if (UseTLAB) {
 574     assert(SafepointSynchronize::is_at_safepoint() ||
 575          !is_init_completed(),
 576          "should only resize tlabs at safepoint");
 577 
 578     ThreadLocalAllocBuffer::resize_all_tlabs();
 579   }
 580 }
 581 
 582 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
 583   assert(timer != NULL, "timer is null");
 584   if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
 585     GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
 586     HeapDumper::dump_heap();
 587   }
 588 
 589   LogTarget(Trace, gc, classhisto) lt;
 590   if (lt.is_enabled()) {
 591     GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
 592     ResourceMark rm;
 593     LogStream ls(lt);
 594     VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
 595     inspector.doit();
 596   }
 597 }
 598 
 599 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
 600   full_gc_dump(timer, true);
 601 }
 602 
 603 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
 604   full_gc_dump(timer, false);
 605 }
 606 
 607 void CollectedHeap::initialize_reserved_region(HeapWord *start, HeapWord *end) {
 608   // It is important to do this in a way such that concurrent readers can't
 609   // temporarily think something is in the heap.  (Seen this happen in asserts.)
 610   _reserved.set_word_size(0);
 611   _reserved.set_start(start);
 612   _reserved.set_end(end);
 613 }