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 BarrierSet::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 }