1 /* 2 * Copyright (c) 2001, 2021, 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/classLoaderData.hpp" 27 #include "classfile/vmClasses.hpp" 28 #include "gc/shared/allocTracer.hpp" 29 #include "gc/shared/barrierSet.hpp" 30 #include "gc/shared/collectedHeap.hpp" 31 #include "gc/shared/collectedHeap.inline.hpp" 32 #include "gc/shared/gcLocker.inline.hpp" 33 #include "gc/shared/gcHeapSummary.hpp" 34 #include "gc/shared/stringdedup/stringDedup.hpp" 35 #include "gc/shared/gcTrace.hpp" 36 #include "gc/shared/gcTraceTime.inline.hpp" 37 #include "gc/shared/gcVMOperations.hpp" 38 #include "gc/shared/gcWhen.hpp" 39 #include "gc/shared/gc_globals.hpp" 40 #include "gc/shared/memAllocator.hpp" 41 #include "gc/shared/tlab_globals.hpp" 42 #include "logging/log.hpp" 43 #include "logging/logStream.hpp" 44 #include "memory/classLoaderMetaspace.hpp" 45 #include "memory/metaspaceUtils.hpp" 46 #include "memory/resourceArea.hpp" 47 #include "memory/universe.hpp" 48 #include "oops/instanceMirrorKlass.hpp" 49 #include "oops/oop.inline.hpp" 50 #include "runtime/handles.inline.hpp" 51 #include "runtime/init.hpp" 52 #include "runtime/perfData.hpp" 53 #include "runtime/thread.inline.hpp" 54 #include "runtime/threadSMR.hpp" 55 #include "runtime/vmThread.hpp" 56 #include "services/heapDumper.hpp" 57 #include "utilities/align.hpp" 58 #include "utilities/copy.hpp" 59 #include "utilities/events.hpp" 60 61 class ClassLoaderData; 62 63 size_t CollectedHeap::_filler_array_max_size = 0; 64 65 class GCMessage : public FormatBuffer<1024> { 66 public: 67 bool is_before; 68 }; 69 70 template <> 71 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) { 72 st->print_cr("GC heap %s", m.is_before ? "before" : "after"); 73 st->print_raw(m); 74 } 75 76 class GCHeapLog : public EventLogBase<GCMessage> { 77 private: 78 void log_heap(CollectedHeap* heap, bool before); 79 80 public: 81 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {} 82 83 void log_heap_before(CollectedHeap* heap) { 84 log_heap(heap, true); 85 } 86 void log_heap_after(CollectedHeap* heap) { 87 log_heap(heap, false); 88 } 89 }; 90 91 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) { 92 if (!should_log()) { 93 return; 94 } 95 96 double timestamp = fetch_timestamp(); 97 MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag); 98 int index = compute_log_index(); 99 _records[index].thread = NULL; // Its the GC thread so it's not that interesting. 100 _records[index].timestamp = timestamp; 101 _records[index].data.is_before = before; 102 stringStream st(_records[index].data.buffer(), _records[index].data.size()); 103 104 st.print_cr("{Heap %s GC invocations=%u (full %u):", 105 before ? "before" : "after", 106 heap->total_collections(), 107 heap->total_full_collections()); 108 109 heap->print_on(&st); 110 st.print_cr("}"); 111 } 112 113 size_t CollectedHeap::unused() const { 114 MutexLocker ml(Heap_lock); 115 return capacity() - used(); 116 } 117 118 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() { 119 size_t capacity_in_words = capacity() / HeapWordSize; 120 121 return VirtualSpaceSummary( 122 _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end()); 123 } 124 125 GCHeapSummary CollectedHeap::create_heap_summary() { 126 VirtualSpaceSummary heap_space = create_heap_space_summary(); 127 return GCHeapSummary(heap_space, used()); 128 } 129 130 MetaspaceSummary CollectedHeap::create_metaspace_summary() { 131 const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary = 132 MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType); 133 const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary = 134 MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType); 135 return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), 136 MetaspaceUtils::get_combined_statistics(), 137 ms_chunk_free_list_summary, class_chunk_free_list_summary); 138 } 139 140 void CollectedHeap::print_heap_before_gc() { 141 LogTarget(Debug, gc, heap) lt; 142 if (lt.is_enabled()) { 143 LogStream ls(lt); 144 ls.print_cr("Heap before GC invocations=%u (full %u):", total_collections(), total_full_collections()); 145 ResourceMark rm; 146 print_on(&ls); 147 } 148 149 if (_gc_heap_log != NULL) { 150 _gc_heap_log->log_heap_before(this); 151 } 152 } 153 154 void CollectedHeap::print_heap_after_gc() { 155 LogTarget(Debug, gc, heap) lt; 156 if (lt.is_enabled()) { 157 LogStream ls(lt); 158 ls.print_cr("Heap after GC invocations=%u (full %u):", total_collections(), total_full_collections()); 159 ResourceMark rm; 160 print_on(&ls); 161 } 162 163 if (_gc_heap_log != NULL) { 164 _gc_heap_log->log_heap_after(this); 165 } 166 } 167 168 void CollectedHeap::print() const { print_on(tty); } 169 170 void CollectedHeap::print_on_error(outputStream* st) const { 171 st->print_cr("Heap:"); 172 print_extended_on(st); 173 st->cr(); 174 175 BarrierSet* bs = BarrierSet::barrier_set(); 176 if (bs != NULL) { 177 bs->print_on(st); 178 } 179 } 180 181 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) { 182 const GCHeapSummary& heap_summary = create_heap_summary(); 183 gc_tracer->report_gc_heap_summary(when, heap_summary); 184 185 const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); 186 gc_tracer->report_metaspace_summary(when, metaspace_summary); 187 } 188 189 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) { 190 trace_heap(GCWhen::BeforeGC, gc_tracer); 191 } 192 193 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) { 194 trace_heap(GCWhen::AfterGC, gc_tracer); 195 } 196 197 // Default implementation, for collectors that don't support the feature. 198 bool CollectedHeap::supports_concurrent_gc_breakpoints() const { 199 return false; 200 } 201 202 bool CollectedHeap::is_oop(oop object) const { 203 if (!is_object_aligned(object)) { 204 return false; 205 } 206 207 if (!is_in(object)) { 208 return false; 209 } 210 211 return true; 212 } 213 214 // Memory state functions. 215 216 217 CollectedHeap::CollectedHeap() : 218 _capacity_at_last_gc(0), 219 _used_at_last_gc(0), 220 _is_gc_active(false), 221 _last_whole_heap_examined_time_ns(os::javaTimeNanos()), 222 _total_collections(0), 223 _total_full_collections(0), 224 _gc_cause(GCCause::_no_gc), 225 _gc_lastcause(GCCause::_no_gc) 226 { 227 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT)); 228 const size_t elements_per_word = HeapWordSize / sizeof(jint); 229 int header_size_in_bytes = arrayOopDesc::base_offset_in_bytes(T_INT); 230 assert(header_size_in_bytes % sizeof(jint) == 0, "must be aligned to int"); 231 int header_size_in_ints = header_size_in_bytes / sizeof(jint); 232 _filler_array_max_size = align_object_size((header_size_in_ints + max_len) / elements_per_word); 233 234 NOT_PRODUCT(_promotion_failure_alot_count = 0;) 235 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;) 236 237 if (UsePerfData) { 238 EXCEPTION_MARK; 239 240 // create the gc cause jvmstat counters 241 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause", 242 80, GCCause::to_string(_gc_cause), CHECK); 243 244 _perf_gc_lastcause = 245 PerfDataManager::create_string_variable(SUN_GC, "lastCause", 246 80, GCCause::to_string(_gc_lastcause), CHECK); 247 } 248 249 // Create the ring log 250 if (LogEvents) { 251 _gc_heap_log = new GCHeapLog(); 252 } else { 253 _gc_heap_log = NULL; 254 } 255 } 256 257 // This interface assumes that it's being called by the 258 // vm thread. It collects the heap assuming that the 259 // heap lock is already held and that we are executing in 260 // the context of the vm thread. 261 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { 262 Thread* thread = Thread::current(); 263 assert(thread->is_VM_thread(), "Precondition#1"); 264 assert(Heap_lock->is_locked(), "Precondition#2"); 265 GCCauseSetter gcs(this, cause); 266 switch (cause) { 267 case GCCause::_heap_inspection: 268 case GCCause::_heap_dump: 269 case GCCause::_metadata_GC_threshold : { 270 HandleMark hm(thread); 271 do_full_collection(false); // don't clear all soft refs 272 break; 273 } 274 case GCCause::_archive_time_gc: 275 case GCCause::_metadata_GC_clear_soft_refs: { 276 HandleMark hm(thread); 277 do_full_collection(true); // do clear all soft refs 278 break; 279 } 280 default: 281 ShouldNotReachHere(); // Unexpected use of this function 282 } 283 } 284 285 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 286 size_t word_size, 287 Metaspace::MetadataType mdtype) { 288 uint loop_count = 0; 289 uint gc_count = 0; 290 uint full_gc_count = 0; 291 292 assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock"); 293 294 do { 295 MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype); 296 if (result != NULL) { 297 return result; 298 } 299 300 if (GCLocker::is_active_and_needs_gc()) { 301 // If the GCLocker is active, just expand and allocate. 302 // If that does not succeed, wait if this thread is not 303 // in a critical section itself. 304 result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype); 305 if (result != NULL) { 306 return result; 307 } 308 JavaThread* jthr = JavaThread::current(); 309 if (!jthr->in_critical()) { 310 // Wait for JNI critical section to be exited 311 GCLocker::stall_until_clear(); 312 // The GC invoked by the last thread leaving the critical 313 // section will be a young collection and a full collection 314 // is (currently) needed for unloading classes so continue 315 // to the next iteration to get a full GC. 316 continue; 317 } else { 318 if (CheckJNICalls) { 319 fatal("Possible deadlock due to allocating while" 320 " in jni critical section"); 321 } 322 return NULL; 323 } 324 } 325 326 { // Need lock to get self consistent gc_count's 327 MutexLocker ml(Heap_lock); 328 gc_count = Universe::heap()->total_collections(); 329 full_gc_count = Universe::heap()->total_full_collections(); 330 } 331 332 // Generate a VM operation 333 VM_CollectForMetadataAllocation op(loader_data, 334 word_size, 335 mdtype, 336 gc_count, 337 full_gc_count, 338 GCCause::_metadata_GC_threshold); 339 VMThread::execute(&op); 340 341 // If GC was locked out, try again. Check before checking success because the 342 // prologue could have succeeded and the GC still have been locked out. 343 if (op.gc_locked()) { 344 continue; 345 } 346 347 if (op.prologue_succeeded()) { 348 return op.result(); 349 } 350 loop_count++; 351 if ((QueuedAllocationWarningCount > 0) && 352 (loop_count % QueuedAllocationWarningCount == 0)) { 353 log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times," 354 " size=" SIZE_FORMAT, loop_count, word_size); 355 } 356 } while (true); // Until a GC is done 357 } 358 359 MemoryUsage CollectedHeap::memory_usage() { 360 return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity()); 361 } 362 363 void CollectedHeap::set_gc_cause(GCCause::Cause v) { 364 if (UsePerfData) { 365 _gc_lastcause = _gc_cause; 366 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause)); 367 _perf_gc_cause->set_value(GCCause::to_string(v)); 368 } 369 _gc_cause = v; 370 } 371 372 #ifndef PRODUCT 373 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) { 374 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 375 // please note mismatch between size (in 32/64 bit words), and ju_addr that always point to a 32 bit word 376 for (juint* ju_addr = reinterpret_cast<juint*>(addr); ju_addr < reinterpret_cast<juint*>(addr + size); ++ju_addr) { 377 assert(*ju_addr == badHeapWordVal, "Found non badHeapWordValue in pre-allocation check"); 378 } 379 } 380 } 381 #endif // PRODUCT 382 383 size_t CollectedHeap::max_tlab_size() const { 384 // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE]. 385 // This restriction could be removed by enabling filling with multiple arrays. 386 // If we compute that the reasonable way as 387 // header_size + ((sizeof(jint) * max_jint) / HeapWordSize) 388 // we'll overflow on the multiply, so we do the divide first. 389 // We actually lose a little by dividing first, 390 // but that just makes the TLAB somewhat smaller than the biggest array, 391 // which is fine, since we'll be able to fill that. 392 int header_size_in_bytes = typeArrayOopDesc::base_offset_in_bytes(T_INT); 393 assert(header_size_in_bytes % sizeof(jint) == 0, "header size must align to int"); 394 size_t max_int_size = header_size_in_bytes / HeapWordSize + 395 sizeof(jint) * 396 ((juint) max_jint / (size_t) HeapWordSize); 397 return align_down(max_int_size, MinObjAlignment); 398 } 399 400 size_t CollectedHeap::filler_array_min_size() { 401 int aligned_header_size_words = align_up(arrayOopDesc::base_offset_in_bytes(T_INT), HeapWordSize) / HeapWordSize; 402 return align_object_size(aligned_header_size_words); // align to MinObjAlignment 403 } 404 405 #ifdef ASSERT 406 void CollectedHeap::fill_args_check(HeapWord* start, size_t words) 407 { 408 assert(words >= min_fill_size(), "too small to fill"); 409 assert(is_object_aligned(words), "unaligned size"); 410 } 411 412 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap) 413 { 414 if (ZapFillerObjects && zap) { 415 int payload_start = align_up(arrayOopDesc::base_offset_in_bytes(T_INT), HeapWordSize) / HeapWordSize; 416 Copy::fill_to_words(start + payload_start, 417 words - payload_start, 0XDEAFBABE); 418 } 419 } 420 #endif // ASSERT 421 422 void 423 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap) 424 { 425 assert(words >= filler_array_min_size(), "too small for an array"); 426 assert(words <= filler_array_max_size(), "too big for a single object"); 427 428 const size_t payload_size_bytes = words * HeapWordSize - arrayOopDesc::base_offset_in_bytes(T_INT); 429 assert(payload_size_bytes % sizeof(jint) == 0, "must be int aligned"); 430 const size_t len = payload_size_bytes / sizeof(jint); 431 assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len); 432 433 ObjArrayAllocator allocator(Universe::intArrayKlassObj(), words, (int)len, /* do_zero */ false); 434 allocator.initialize(start); 435 DEBUG_ONLY(zap_filler_array(start, words, zap);) 436 } 437 438 void 439 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap) 440 { 441 assert(words <= filler_array_max_size(), "too big for a single object"); 442 443 if (words >= filler_array_min_size()) { 444 fill_with_array(start, words, zap); 445 } else if (words > 0) { 446 assert(words == min_fill_size(), "unaligned size"); 447 ObjAllocator allocator(vmClasses::Object_klass(), words); 448 allocator.initialize(start); 449 } 450 } 451 452 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap) 453 { 454 DEBUG_ONLY(fill_args_check(start, words);) 455 HandleMark hm(Thread::current()); // Free handles before leaving. 456 fill_with_object_impl(start, words, zap); 457 } 458 459 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap) 460 { 461 DEBUG_ONLY(fill_args_check(start, words);) 462 HandleMark hm(Thread::current()); // Free handles before leaving. 463 464 // Multiple objects may be required depending on the filler array maximum size. Fill 465 // the range up to that with objects that are filler_array_max_size sized. The 466 // remainder is filled with a single object. 467 const size_t min = min_fill_size(); 468 const size_t max = filler_array_max_size(); 469 while (words > max) { 470 const size_t cur = (words - max) >= min ? max : max - min; 471 fill_with_array(start, cur, zap); 472 start += cur; 473 words -= cur; 474 } 475 476 fill_with_object_impl(start, words, zap); 477 } 478 479 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) { 480 CollectedHeap::fill_with_object(start, end, zap); 481 } 482 483 size_t CollectedHeap::min_dummy_object_size() const { 484 return oopDesc::header_size(); 485 } 486 487 size_t CollectedHeap::tlab_alloc_reserve() const { 488 size_t min_size = min_dummy_object_size(); 489 return min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0; 490 } 491 492 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size, 493 size_t requested_size, 494 size_t* actual_size) { 495 guarantee(false, "thread-local allocation buffers not supported"); 496 return NULL; 497 } 498 499 void CollectedHeap::ensure_parsability(bool retire_tlabs) { 500 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(), 501 "Should only be called at a safepoint or at start-up"); 502 503 ThreadLocalAllocStats stats; 504 505 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) { 506 BarrierSet::barrier_set()->make_parsable(thread); 507 if (UseTLAB) { 508 if (retire_tlabs) { 509 thread->tlab().retire(&stats); 510 } else { 511 thread->tlab().make_parsable(); 512 } 513 } 514 } 515 516 stats.publish(); 517 } 518 519 void CollectedHeap::resize_all_tlabs() { 520 assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(), 521 "Should only resize tlabs at safepoint"); 522 523 if (UseTLAB && ResizeTLAB) { 524 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) { 525 thread->tlab().resize(); 526 } 527 } 528 } 529 530 jlong CollectedHeap::millis_since_last_whole_heap_examined() { 531 return (os::javaTimeNanos() - _last_whole_heap_examined_time_ns) / NANOSECS_PER_MILLISEC; 532 } 533 534 void CollectedHeap::record_whole_heap_examined_timestamp() { 535 _last_whole_heap_examined_time_ns = os::javaTimeNanos(); 536 } 537 538 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) { 539 assert(timer != NULL, "timer is null"); 540 if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) { 541 GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer); 542 HeapDumper::dump_heap(); 543 } 544 545 LogTarget(Trace, gc, classhisto) lt; 546 if (lt.is_enabled()) { 547 GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer); 548 ResourceMark rm; 549 LogStream ls(lt); 550 VM_GC_HeapInspection inspector(&ls, false /* ! full gc */); 551 inspector.doit(); 552 } 553 } 554 555 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) { 556 full_gc_dump(timer, true); 557 } 558 559 void CollectedHeap::post_full_gc_dump(GCTimer* timer) { 560 full_gc_dump(timer, false); 561 } 562 563 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) { 564 // It is important to do this in a way such that concurrent readers can't 565 // temporarily think something is in the heap. (Seen this happen in asserts.) 566 _reserved.set_word_size(0); 567 _reserved.set_start((HeapWord*)rs.base()); 568 _reserved.set_end((HeapWord*)rs.end()); 569 } 570 571 void CollectedHeap::post_initialize() { 572 StringDedup::initialize(); 573 initialize_serviceability(); 574 } 575 576 #ifndef PRODUCT 577 578 bool CollectedHeap::promotion_should_fail(volatile size_t* count) { 579 // Access to count is not atomic; the value does not have to be exact. 580 if (PromotionFailureALot) { 581 const size_t gc_num = total_collections(); 582 const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number; 583 if (elapsed_gcs >= PromotionFailureALotInterval) { 584 // Test for unsigned arithmetic wrap-around. 585 if (++*count >= PromotionFailureALotCount) { 586 *count = 0; 587 return true; 588 } 589 } 590 } 591 return false; 592 } 593 594 bool CollectedHeap::promotion_should_fail() { 595 return promotion_should_fail(&_promotion_failure_alot_count); 596 } 597 598 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) { 599 if (PromotionFailureALot) { 600 _promotion_failure_alot_gc_number = total_collections(); 601 *count = 0; 602 } 603 } 604 605 void CollectedHeap::reset_promotion_should_fail() { 606 reset_promotion_should_fail(&_promotion_failure_alot_count); 607 } 608 609 #endif // #ifndef PRODUCT 610 611 bool CollectedHeap::supports_object_pinning() const { 612 return false; 613 } 614 615 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) { 616 ShouldNotReachHere(); 617 return NULL; 618 } 619 620 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) { 621 ShouldNotReachHere(); 622 } 623 624 bool CollectedHeap::is_archived_object(oop object) const { 625 return false; 626 } 627 628 uint32_t CollectedHeap::hash_oop(oop obj) const { 629 const uintptr_t addr = cast_from_oop<uintptr_t>(obj); 630 return static_cast<uint32_t>(addr >> LogMinObjAlignment); 631 } 632 633 // It's the caller's responsibility to ensure glitch-freedom 634 // (if required). 635 void CollectedHeap::update_capacity_and_used_at_gc() { 636 _capacity_at_last_gc = capacity(); 637 _used_at_last_gc = used(); 638 }