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 "services/heapDumper.hpp" 44 #include "utilities/align.hpp" 45 46 47 #ifdef ASSERT 48 int CollectedHeap::_fire_out_of_memory_count = 0; 49 #endif 50 51 size_t CollectedHeap::_filler_array_max_size = 0; 52 53 template <> 54 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) { 55 st->print_cr("GC heap %s", m.is_before ? "before" : "after"); 56 st->print_raw(m); 57 } 58 59 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) { 60 if (!should_log()) { 61 return; 62 } 63 64 double timestamp = fetch_timestamp(); 65 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag); 66 int index = compute_log_index(); 67 _records[index].thread = NULL; // Its the GC thread so it's not that interesting. 68 _records[index].timestamp = timestamp; 69 _records[index].data.is_before = before; 70 stringStream st(_records[index].data.buffer(), _records[index].data.size()); 71 72 st.print_cr("{Heap %s GC invocations=%u (full %u):", 73 before ? "before" : "after", 74 heap->total_collections(), 75 heap->total_full_collections()); 76 77 heap->print_on(&st); 78 st.print_cr("}"); 79 } 80 81 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() { 82 size_t capacity_in_words = capacity() / HeapWordSize; 83 84 return VirtualSpaceSummary( 85 reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end()); 86 } 87 88 GCHeapSummary CollectedHeap::create_heap_summary() { 89 VirtualSpaceSummary heap_space = create_heap_space_summary(); 90 return GCHeapSummary(heap_space, used()); 91 } 92 93 MetaspaceSummary CollectedHeap::create_metaspace_summary() { 94 const MetaspaceSizes meta_space( 95 MetaspaceAux::committed_bytes(), 96 MetaspaceAux::used_bytes(), 97 MetaspaceAux::reserved_bytes()); 98 const MetaspaceSizes data_space( 99 MetaspaceAux::committed_bytes(Metaspace::NonClassType), 100 MetaspaceAux::used_bytes(Metaspace::NonClassType), 101 MetaspaceAux::reserved_bytes(Metaspace::NonClassType)); 102 const MetaspaceSizes class_space( 103 MetaspaceAux::committed_bytes(Metaspace::ClassType), 104 MetaspaceAux::used_bytes(Metaspace::ClassType), 105 MetaspaceAux::reserved_bytes(Metaspace::ClassType)); 106 107 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary = 108 MetaspaceAux::chunk_free_list_summary(Metaspace::NonClassType); 109 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary = 110 MetaspaceAux::chunk_free_list_summary(Metaspace::ClassType); 111 112 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space, 113 ms_chunk_free_list_summary, class_chunk_free_list_summary); 114 } 115 116 void CollectedHeap::print_heap_before_gc() { 117 Universe::print_heap_before_gc(); 118 if (_gc_heap_log != NULL) { 119 _gc_heap_log->log_heap_before(this); 120 } 121 } 122 123 void CollectedHeap::print_heap_after_gc() { 124 Universe::print_heap_after_gc(); 125 if (_gc_heap_log != NULL) { 126 _gc_heap_log->log_heap_after(this); 127 } 128 } 129 130 void CollectedHeap::print_on_error(outputStream* st) const { 131 st->print_cr("Heap:"); 132 print_extended_on(st); 133 st->cr(); 134 135 _barrier_set->print_on(st); 136 } 137 138 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 139 const GCHeapSummary& heap_summary = create_heap_summary(); 140 gc_tracer->report_gc_heap_summary(when, heap_summary); 141 142 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 143 gc_tracer->report_metaspace_summary(when, metaspace_summary); 144 } 145 146 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) { 147 trace_heap(GCWhen::BeforeGC, gc_tracer); 148 } 149 150 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) { 151 trace_heap(GCWhen::AfterGC, gc_tracer); 152 } 153 154 // WhiteBox API support for concurrent collectors. These are the 155 // default implementations, for collectors which don't support this 156 // feature. 157 bool CollectedHeap::supports_concurrent_phase_control() const { 158 return false; 159 } 160 161 const char* const* CollectedHeap::concurrent_phases() const { 162 static const char* const result[] = { NULL }; 163 return result; 164 } 165 166 bool CollectedHeap::request_concurrent_phase(const char* phase) { 167 return false; 168 } 169 170 // Memory state functions. 171 172 173 CollectedHeap::CollectedHeap() : 174 _barrier_set(NULL), 175 _is_gc_active(false), 176 _total_collections(0), 177 _total_full_collections(0), 178 _gc_cause(GCCause::_no_gc), 179 _gc_lastcause(GCCause::_no_gc), 180 _defer_initial_card_mark(false) // strengthened by subclass in pre_initialize() below. 181 { 182 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT)); 183 const size_t elements_per_word = HeapWordSize / sizeof(jint); 184 _filler_array_max_size = align_object_size(filler_array_hdr_size() + 185 max_len / elements_per_word); 186 187 NOT_PRODUCT(_promotion_failure_alot_count = 0;) 188 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;) 189 190 if (UsePerfData) { 191 EXCEPTION_MARK; 192 193 // create the gc cause jvmstat counters 194 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause", 195 80, GCCause::to_string(_gc_cause), CHECK); 196 197 _perf_gc_lastcause = 198 PerfDataManager::create_string_variable(SUN_GC, "lastCause", 199 80, GCCause::to_string(_gc_lastcause), CHECK); 200 } 201 202 // Create the ring log 203 if (LogEvents) { 204 _gc_heap_log = new GCHeapLog(); 205 } else { 206 _gc_heap_log = NULL; 207 } 208 } 209 210 // This interface assumes that it's being called by the 211 // vm thread. It collects the heap assuming that the 212 // heap lock is already held and that we are executing in 213 // the context of the vm thread. 214 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { 215 assert(Thread::current()->is_VM_thread(), "Precondition#1"); 216 assert(Heap_lock->is_locked(), "Precondition#2"); 217 GCCauseSetter gcs(this, cause); 218 switch (cause) { 219 case GCCause::_heap_inspection: 220 case GCCause::_heap_dump: 221 case GCCause::_metadata_GC_threshold : { 222 HandleMark hm; 223 do_full_collection(false); // don't clear all soft refs 224 break; 225 } 226 case GCCause::_metadata_GC_clear_soft_refs: { 227 HandleMark hm; 228 do_full_collection(true); // do clear all soft refs 229 break; 230 } 231 default: 232 ShouldNotReachHere(); // Unexpected use of this function 233 } 234 } 235 236 void CollectedHeap::set_barrier_set(BarrierSet* barrier_set) { 237 _barrier_set = barrier_set; 238 oopDesc::set_bs(_barrier_set); 239 } 240 241 void CollectedHeap::pre_initialize() { 242 // Used for ReduceInitialCardMarks (when COMPILER2 is used); 243 // otherwise remains unused. 244 #if defined(COMPILER2) || INCLUDE_JVMCI 245 _defer_initial_card_mark = is_server_compilation_mode_vm() && ReduceInitialCardMarks && can_elide_tlab_store_barriers() 246 && (DeferInitialCardMark || card_mark_must_follow_store()); 247 #else 248 assert(_defer_initial_card_mark == false, "Who would set it?"); 249 #endif 250 } 251 252 #ifndef PRODUCT 253 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) { 254 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 255 for (size_t slot = 0; slot < size; slot += 1) { 256 assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal), 257 "Found badHeapWordValue in post-allocation check"); 258 } 259 } 260 } 261 262 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) { 263 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 264 for (size_t slot = 0; slot < size; slot += 1) { 265 assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal), 266 "Found non badHeapWordValue in pre-allocation check"); 267 } 268 } 269 } 270 #endif // PRODUCT 271 272 #ifdef ASSERT 273 void CollectedHeap::check_for_valid_allocation_state() { 274 Thread *thread = Thread::current(); 275 // How to choose between a pending exception and a potential 276 // OutOfMemoryError? Don't allow pending exceptions. 277 // This is a VM policy failure, so how do we exhaustively test it? 278 assert(!thread->has_pending_exception(), 279 "shouldn't be allocating with pending exception"); 280 if (StrictSafepointChecks) { 281 assert(thread->allow_allocation(), 282 "Allocation done by thread for which allocation is blocked " 283 "by No_Allocation_Verifier!"); 284 // Allocation of an oop can always invoke a safepoint, 285 // hence, the true argument 286 thread->check_for_valid_safepoint_state(true); 287 } 288 } 289 #endif 290 291 HeapWord* CollectedHeap::allocate_from_tlab_slow(Klass* klass, Thread* thread, size_t size) { 292 293 // Retain tlab and allocate object in shared space if 294 // the amount free in the tlab is too large to discard. 295 if (thread->tlab().free() > thread->tlab().refill_waste_limit()) { 296 thread->tlab().record_slow_allocation(size); 297 return NULL; 298 } 299 300 // Discard tlab and allocate a new one. 301 // To minimize fragmentation, the last TLAB may be smaller than the rest. 302 size_t new_tlab_size = thread->tlab().compute_size(size); 303 304 thread->tlab().clear_before_allocation(); 305 306 if (new_tlab_size == 0) { 307 return NULL; 308 } 309 310 // Allocate a new TLAB... 311 HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size); 312 if (obj == NULL) { 313 return NULL; 314 } 315 316 AllocTracer::send_allocation_in_new_tlab_event(klass, new_tlab_size * HeapWordSize, size * HeapWordSize); 317 318 if (ZeroTLAB) { 319 // ..and clear it. 320 Copy::zero_to_words(obj, new_tlab_size); 321 } else { 322 // ...and zap just allocated object. 323 #ifdef ASSERT 324 // Skip mangling the space corresponding to the object header to 325 // ensure that the returned space is not considered parsable by 326 // any concurrent GC thread. 327 size_t hdr_size = oopDesc::header_size(); 328 Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal); 329 #endif // ASSERT 330 } 331 thread->tlab().fill(obj, obj + size, new_tlab_size); 332 return obj; 333 } 334 335 void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) { 336 MemRegion deferred = thread->deferred_card_mark(); 337 if (!deferred.is_empty()) { 338 assert(_defer_initial_card_mark, "Otherwise should be empty"); 339 { 340 // Verify that the storage points to a parsable object in heap 341 DEBUG_ONLY(oop old_obj = oop(deferred.start());) 342 assert(is_in(old_obj), "Not in allocated heap"); 343 assert(!can_elide_initializing_store_barrier(old_obj), 344 "Else should have been filtered in new_store_pre_barrier()"); 345 assert(oopDesc::is_oop(old_obj, true), "Not an oop"); 346 assert(deferred.word_size() == (size_t)(old_obj->size()), 347 "Mismatch: multiple objects?"); 348 } 349 BarrierSet* bs = barrier_set(); 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_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 bs->write_region(mr); 433 } 434 } 435 return new_obj; 436 } 437 438 size_t CollectedHeap::filler_array_hdr_size() { 439 return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long 440 } 441 442 size_t CollectedHeap::filler_array_min_size() { 443 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment 444 } 445 446 #ifdef ASSERT 447 void CollectedHeap::fill_args_check(HeapWord* start, size_t words) 448 { 449 assert(words >= min_fill_size(), "too small to fill"); 450 assert(is_object_aligned(words), "unaligned size"); 451 assert(Universe::heap()->is_in_reserved(start), "not in heap"); 452 assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap"); 453 } 454 455 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap) 456 { 457 if (ZapFillerObjects && zap) { 458 Copy::fill_to_words(start + filler_array_hdr_size(), 459 words - filler_array_hdr_size(), 0XDEAFBABE); 460 } 461 } 462 #endif // ASSERT 463 464 void 465 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap) 466 { 467 assert(words >= filler_array_min_size(), "too small for an array"); 468 assert(words <= filler_array_max_size(), "too big for a single object"); 469 470 const size_t payload_size = words - filler_array_hdr_size(); 471 const size_t len = payload_size * HeapWordSize / sizeof(jint); 472 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len); 473 474 // Set the length first for concurrent GC. 475 ((arrayOop)start)->set_length((int)len); 476 post_allocation_setup_common(Universe::intArrayKlassObj(), start); 477 DEBUG_ONLY(zap_filler_array(start, words, zap);) 478 } 479 480 void 481 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap) 482 { 483 assert(words <= filler_array_max_size(), "too big for a single object"); 484 485 if (words >= filler_array_min_size()) { 486 fill_with_array(start, words, zap); 487 } else if (words > 0) { 488 assert(words == min_fill_size(), "unaligned size"); 489 post_allocation_setup_common(SystemDictionary::Object_klass(), start); 490 } 491 } 492 493 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap) 494 { 495 DEBUG_ONLY(fill_args_check(start, words);) 496 HandleMark hm; // Free handles before leaving. 497 fill_with_object_impl(start, words, zap); 498 } 499 500 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap) 501 { 502 DEBUG_ONLY(fill_args_check(start, words);) 503 HandleMark hm; // Free handles before leaving. 504 505 // Multiple objects may be required depending on the filler array maximum size. Fill 506 // the range up to that with objects that are filler_array_max_size sized. The 507 // remainder is filled with a single object. 508 const size_t min = min_fill_size(); 509 const size_t max = filler_array_max_size(); 510 while (words > max) { 511 const size_t cur = (words - max) >= min ? max : max - min; 512 fill_with_array(start, cur, zap); 513 start += cur; 514 words -= cur; 515 } 516 517 fill_with_object_impl(start, words, zap); 518 } 519 520 HeapWord* CollectedHeap::allocate_new_tlab(size_t size) { 521 guarantee(false, "thread-local allocation buffers not supported"); 522 return NULL; 523 } 524 525 void CollectedHeap::ensure_parsability(bool retire_tlabs) { 526 // The second disjunct in the assertion below makes a concession 527 // for the start-up verification done while the VM is being 528 // created. Callers be careful that you know that mutators 529 // aren't going to interfere -- for instance, this is permissible 530 // if we are still single-threaded and have either not yet 531 // started allocating (nothing much to verify) or we have 532 // started allocating but are now a full-fledged JavaThread 533 // (and have thus made our TLAB's) available for filling. 534 assert(SafepointSynchronize::is_at_safepoint() || 535 !is_init_completed(), 536 "Should only be called at a safepoint or at start-up" 537 " otherwise concurrent mutator activity may make heap " 538 " unparsable again"); 539 const bool use_tlab = UseTLAB; 540 const bool deferred = _defer_initial_card_mark; 541 // The main thread starts allocating via a TLAB even before it 542 // has added itself to the threads list at vm boot-up. 543 assert(!use_tlab || Threads::first() != NULL, 544 "Attempt to fill tlabs before main thread has been added" 545 " to threads list is doomed to failure!"); 546 for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) { 547 if (use_tlab) thread->tlab().make_parsable(retire_tlabs); 548 #if defined(COMPILER2) || INCLUDE_JVMCI 549 // The deferred store barriers must all have been flushed to the 550 // card-table (or other remembered set structure) before GC starts 551 // processing the card-table (or other remembered set). 552 if (deferred) flush_deferred_store_barrier(thread); 553 #else 554 assert(!deferred, "Should be false"); 555 assert(thread->deferred_card_mark().is_empty(), "Should be empty"); 556 #endif 557 } 558 } 559 560 void CollectedHeap::accumulate_statistics_all_tlabs() { 561 if (UseTLAB) { 562 assert(SafepointSynchronize::is_at_safepoint() || 563 !is_init_completed(), 564 "should only accumulate statistics on tlabs at safepoint"); 565 566 ThreadLocalAllocBuffer::accumulate_statistics_before_gc(); 567 } 568 } 569 570 void CollectedHeap::resize_all_tlabs() { 571 if (UseTLAB) { 572 assert(SafepointSynchronize::is_at_safepoint() || 573 !is_init_completed(), 574 "should only resize tlabs at safepoint"); 575 576 ThreadLocalAllocBuffer::resize_all_tlabs(); 577 } 578 } 579 580 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) { 581 assert(timer != NULL, "timer is null"); 582 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) { 583 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer); 584 HeapDumper::dump_heap(); 585 } 586 587 LogTarget(Trace, gc, classhisto) lt; 588 if (lt.is_enabled()) { 589 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer); 590 ResourceMark rm; 591 LogStream ls(lt); 592 VM_GC_HeapInspection inspector(&ls, 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 }