rev 58079 : 8238633: JVMTI heap walk should consult GC for marking oops

   1 /*
   2  * Copyright (c) 2001, 2020, 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.hpp"
  29 #include "gc/shared/collectedHeap.hpp"
  30 #include "gc/shared/collectedHeap.inline.hpp"
  31 #include "gc/shared/gcLocker.inline.hpp"
  32 #include "gc/shared/gcHeapSummary.hpp"
  33 #include "gc/shared/gcTrace.hpp"
  34 #include "gc/shared/gcTraceTime.inline.hpp"
  35 #include "gc/shared/gcVMOperations.hpp"
  36 #include "gc/shared/gcWhen.hpp"
  37 #include "gc/shared/memAllocator.hpp"
  38 #include "logging/log.hpp"
  39 #include "memory/metaspace.hpp"
  40 #include "memory/resourceArea.hpp"
  41 #include "memory/universe.hpp"
  42 #include "oops/instanceMirrorKlass.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "runtime/handles.inline.hpp"
  45 #include "runtime/init.hpp"
  46 #include "runtime/thread.inline.hpp"
  47 #include "runtime/threadSMR.hpp"
  48 #include "runtime/vmThread.hpp"
  49 #include "services/heapDumper.hpp"
  50 #include "utilities/align.hpp"
  51 #include "utilities/copy.hpp"
  52 
  53 class ClassLoaderData;
  54 
  55 size_t CollectedHeap::_filler_array_max_size = 0;
  56 
  57 template <>
  58 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
  59   st->print_cr("GC heap %s", m.is_before ? "before" : "after");
  60   st->print_raw(m);
  61 }
  62 
  63 void GCHeapLog::log_heap(CollectedHeap* heap, bool before) {
  64   if (!should_log()) {
  65     return;
  66   }
  67 
  68   double timestamp = fetch_timestamp();
  69   MutexLocker ml(&_mutex, Mutex::_no_safepoint_check_flag);
  70   int index = compute_log_index();
  71   _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
  72   _records[index].timestamp = timestamp;
  73   _records[index].data.is_before = before;
  74   stringStream st(_records[index].data.buffer(), _records[index].data.size());
  75 
  76   st.print_cr("{Heap %s GC invocations=%u (full %u):",
  77                  before ? "before" : "after",
  78                  heap->total_collections(),
  79                  heap->total_full_collections());
  80 
  81   heap->print_on(&st);
  82   st.print_cr("}");
  83 }
  84 
  85 size_t CollectedHeap::unused() const {
  86   MutexLocker ml(Heap_lock);
  87   return capacity() - used();
  88 }
  89 
  90 VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
  91   size_t capacity_in_words = capacity() / HeapWordSize;
  92 
  93   return VirtualSpaceSummary(
  94     _reserved.start(), _reserved.start() + capacity_in_words, _reserved.end());
  95 }
  96 
  97 GCHeapSummary CollectedHeap::create_heap_summary() {
  98   VirtualSpaceSummary heap_space = create_heap_space_summary();
  99   return GCHeapSummary(heap_space, used());
 100 }
 101 
 102 MetaspaceSummary CollectedHeap::create_metaspace_summary() {
 103   const MetaspaceSizes meta_space(
 104       MetaspaceUtils::committed_bytes(),
 105       MetaspaceUtils::used_bytes(),
 106       MetaspaceUtils::reserved_bytes());
 107   const MetaspaceSizes data_space(
 108       MetaspaceUtils::committed_bytes(Metaspace::NonClassType),
 109       MetaspaceUtils::used_bytes(Metaspace::NonClassType),
 110       MetaspaceUtils::reserved_bytes(Metaspace::NonClassType));
 111   const MetaspaceSizes class_space(
 112       MetaspaceUtils::committed_bytes(Metaspace::ClassType),
 113       MetaspaceUtils::used_bytes(Metaspace::ClassType),
 114       MetaspaceUtils::reserved_bytes(Metaspace::ClassType));
 115 
 116   const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
 117     MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
 118   const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
 119     MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);
 120 
 121   return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
 122                           ms_chunk_free_list_summary, class_chunk_free_list_summary);
 123 }
 124 
 125 void CollectedHeap::print_heap_before_gc() {
 126   Universe::print_heap_before_gc();
 127   if (_gc_heap_log != NULL) {
 128     _gc_heap_log->log_heap_before(this);
 129   }
 130 }
 131 
 132 void CollectedHeap::print_heap_after_gc() {
 133   Universe::print_heap_after_gc();
 134   if (_gc_heap_log != NULL) {
 135     _gc_heap_log->log_heap_after(this);
 136   }
 137 }
 138 
 139 void CollectedHeap::print() const { print_on(tty); }
 140 
 141 void CollectedHeap::print_on_error(outputStream* st) const {
 142   st->print_cr("Heap:");
 143   print_extended_on(st);
 144   st->cr();
 145 
 146   BarrierSet::barrier_set()->print_on(st);
 147 }
 148 
 149 void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
 150   const GCHeapSummary& heap_summary = create_heap_summary();
 151   gc_tracer->report_gc_heap_summary(when, heap_summary);
 152 
 153   const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
 154   gc_tracer->report_metaspace_summary(when, metaspace_summary);
 155 }
 156 
 157 void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
 158   trace_heap(GCWhen::BeforeGC, gc_tracer);
 159 }
 160 
 161 void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
 162   trace_heap(GCWhen::AfterGC, gc_tracer);
 163 }
 164 
 165 // WhiteBox API support for concurrent collectors.  These are the
 166 // default implementations, for collectors which don't support this
 167 // feature.
 168 bool CollectedHeap::supports_concurrent_phase_control() const {
 169   return false;
 170 }
 171 
 172 bool CollectedHeap::request_concurrent_phase(const char* phase) {
 173   return false;
 174 }
 175 
 176 bool CollectedHeap::is_oop(oop object) const {
 177   if (!is_object_aligned(object)) {
 178     return false;
 179   }
 180 
 181   if (!is_in(object)) {
 182     return false;
 183   }
 184 
 185   if (is_in(object->klass_or_null())) {
 186     return false;
 187   }
 188 
 189   return true;
 190 }
 191 
 192 // Memory state functions.
 193 
 194 
 195 CollectedHeap::CollectedHeap() :
 196   _is_gc_active(false),
 197   _total_collections(0),
 198   _total_full_collections(0),
 199   _gc_cause(GCCause::_no_gc),
 200   _gc_lastcause(GCCause::_no_gc)
 201 {
 202   const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
 203   const size_t elements_per_word = HeapWordSize / sizeof(jint);
 204   _filler_array_max_size = align_object_size(filler_array_hdr_size() +
 205                                              max_len / elements_per_word);
 206 
 207   NOT_PRODUCT(_promotion_failure_alot_count = 0;)
 208   NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
 209 
 210   if (UsePerfData) {
 211     EXCEPTION_MARK;
 212 
 213     // create the gc cause jvmstat counters
 214     _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
 215                              80, GCCause::to_string(_gc_cause), CHECK);
 216 
 217     _perf_gc_lastcause =
 218                 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
 219                              80, GCCause::to_string(_gc_lastcause), CHECK);
 220   }
 221 
 222   // Create the ring log
 223   if (LogEvents) {
 224     _gc_heap_log = new GCHeapLog();
 225   } else {
 226     _gc_heap_log = NULL;
 227   }
 228 }
 229 
 230 // This interface assumes that it's being called by the
 231 // vm thread. It collects the heap assuming that the
 232 // heap lock is already held and that we are executing in
 233 // the context of the vm thread.
 234 void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
 235   assert(Thread::current()->is_VM_thread(), "Precondition#1");
 236   assert(Heap_lock->is_locked(), "Precondition#2");
 237   GCCauseSetter gcs(this, cause);
 238   switch (cause) {
 239     case GCCause::_heap_inspection:
 240     case GCCause::_heap_dump:
 241     case GCCause::_metadata_GC_threshold : {
 242       HandleMark hm;
 243       do_full_collection(false);        // don't clear all soft refs
 244       break;
 245     }
 246     case GCCause::_metadata_GC_clear_soft_refs: {
 247       HandleMark hm;
 248       do_full_collection(true);         // do clear all soft refs
 249       break;
 250     }
 251     default:
 252       ShouldNotReachHere(); // Unexpected use of this function
 253   }
 254 }
 255 
 256 MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 257                                                             size_t word_size,
 258                                                             Metaspace::MetadataType mdtype) {
 259   uint loop_count = 0;
 260   uint gc_count = 0;
 261   uint full_gc_count = 0;
 262 
 263   assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");
 264 
 265   do {
 266     MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
 267     if (result != NULL) {
 268       return result;
 269     }
 270 
 271     if (GCLocker::is_active_and_needs_gc()) {
 272       // If the GCLocker is active, just expand and allocate.
 273       // If that does not succeed, wait if this thread is not
 274       // in a critical section itself.
 275       result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
 276       if (result != NULL) {
 277         return result;
 278       }
 279       JavaThread* jthr = JavaThread::current();
 280       if (!jthr->in_critical()) {
 281         // Wait for JNI critical section to be exited
 282         GCLocker::stall_until_clear();
 283         // The GC invoked by the last thread leaving the critical
 284         // section will be a young collection and a full collection
 285         // is (currently) needed for unloading classes so continue
 286         // to the next iteration to get a full GC.
 287         continue;
 288       } else {
 289         if (CheckJNICalls) {
 290           fatal("Possible deadlock due to allocating while"
 291                 " in jni critical section");
 292         }
 293         return NULL;
 294       }
 295     }
 296 
 297     {  // Need lock to get self consistent gc_count's
 298       MutexLocker ml(Heap_lock);
 299       gc_count      = Universe::heap()->total_collections();
 300       full_gc_count = Universe::heap()->total_full_collections();
 301     }
 302 
 303     // Generate a VM operation
 304     VM_CollectForMetadataAllocation op(loader_data,
 305                                        word_size,
 306                                        mdtype,
 307                                        gc_count,
 308                                        full_gc_count,
 309                                        GCCause::_metadata_GC_threshold);
 310     VMThread::execute(&op);
 311 
 312     // If GC was locked out, try again. Check before checking success because the
 313     // prologue could have succeeded and the GC still have been locked out.
 314     if (op.gc_locked()) {
 315       continue;
 316     }
 317 
 318     if (op.prologue_succeeded()) {
 319       return op.result();
 320     }
 321     loop_count++;
 322     if ((QueuedAllocationWarningCount > 0) &&
 323         (loop_count % QueuedAllocationWarningCount == 0)) {
 324       log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
 325                             " size=" SIZE_FORMAT, loop_count, word_size);
 326     }
 327   } while (true);  // Until a GC is done
 328 }
 329 
 330 MemoryUsage CollectedHeap::memory_usage() {
 331   return MemoryUsage(InitialHeapSize, used(), capacity(), max_capacity());
 332 }
 333 
 334 ObjectMarker* CollectedHeap::object_marker() {
 335   return new DefaultObjectMarker();
 336 }
 337 
 338 #ifndef PRODUCT
 339 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
 340   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 341     // please note mismatch between size (in 32/64 bit words), and ju_addr that always point to a 32 bit word
 342     for (juint* ju_addr = reinterpret_cast<juint*>(addr); ju_addr < reinterpret_cast<juint*>(addr + size); ++ju_addr) {
 343       assert(*ju_addr == badHeapWordVal, "Found non badHeapWordValue in pre-allocation check");
 344     }
 345   }
 346 }
 347 #endif // PRODUCT
 348 
 349 size_t CollectedHeap::max_tlab_size() const {
 350   // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
 351   // This restriction could be removed by enabling filling with multiple arrays.
 352   // If we compute that the reasonable way as
 353   //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
 354   // we'll overflow on the multiply, so we do the divide first.
 355   // We actually lose a little by dividing first,
 356   // but that just makes the TLAB  somewhat smaller than the biggest array,
 357   // which is fine, since we'll be able to fill that.
 358   size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
 359               sizeof(jint) *
 360               ((juint) max_jint / (size_t) HeapWordSize);
 361   return align_down(max_int_size, MinObjAlignment);
 362 }
 363 
 364 size_t CollectedHeap::filler_array_hdr_size() {
 365   return align_object_offset(arrayOopDesc::header_size(T_INT)); // align to Long
 366 }
 367 
 368 size_t CollectedHeap::filler_array_min_size() {
 369   return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
 370 }
 371 
 372 #ifdef ASSERT
 373 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
 374 {
 375   assert(words >= min_fill_size(), "too small to fill");
 376   assert(is_object_aligned(words), "unaligned size");
 377 }
 378 
 379 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
 380 {
 381   if (ZapFillerObjects && zap) {
 382     Copy::fill_to_words(start + filler_array_hdr_size(),
 383                         words - filler_array_hdr_size(), 0XDEAFBABE);
 384   }
 385 }
 386 #endif // ASSERT
 387 
 388 void
 389 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
 390 {
 391   assert(words >= filler_array_min_size(), "too small for an array");
 392   assert(words <= filler_array_max_size(), "too big for a single object");
 393 
 394   const size_t payload_size = words - filler_array_hdr_size();
 395   const size_t len = payload_size * HeapWordSize / sizeof(jint);
 396   assert((int)len >= 0, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);
 397 
 398   ObjArrayAllocator allocator(Universe::intArrayKlassObj(), words, (int)len, /* do_zero */ false);
 399   allocator.initialize(start);
 400   DEBUG_ONLY(zap_filler_array(start, words, zap);)
 401 }
 402 
 403 void
 404 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
 405 {
 406   assert(words <= filler_array_max_size(), "too big for a single object");
 407 
 408   if (words >= filler_array_min_size()) {
 409     fill_with_array(start, words, zap);
 410   } else if (words > 0) {
 411     assert(words == min_fill_size(), "unaligned size");
 412     ObjAllocator allocator(SystemDictionary::Object_klass(), words);
 413     allocator.initialize(start);
 414   }
 415 }
 416 
 417 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
 418 {
 419   DEBUG_ONLY(fill_args_check(start, words);)
 420   HandleMark hm;  // Free handles before leaving.
 421   fill_with_object_impl(start, words, zap);
 422 }
 423 
 424 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
 425 {
 426   DEBUG_ONLY(fill_args_check(start, words);)
 427   HandleMark hm;  // Free handles before leaving.
 428 
 429   // Multiple objects may be required depending on the filler array maximum size. Fill
 430   // the range up to that with objects that are filler_array_max_size sized. The
 431   // remainder is filled with a single object.
 432   const size_t min = min_fill_size();
 433   const size_t max = filler_array_max_size();
 434   while (words > max) {
 435     const size_t cur = (words - max) >= min ? max : max - min;
 436     fill_with_array(start, cur, zap);
 437     start += cur;
 438     words -= cur;
 439   }
 440 
 441   fill_with_object_impl(start, words, zap);
 442 }
 443 
 444 void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
 445   CollectedHeap::fill_with_object(start, end, zap);
 446 }
 447 
 448 size_t CollectedHeap::min_dummy_object_size() const {
 449   return oopDesc::header_size();
 450 }
 451 
 452 size_t CollectedHeap::tlab_alloc_reserve() const {
 453   size_t min_size = min_dummy_object_size();
 454   return min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
 455 }
 456 
 457 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
 458                                            size_t requested_size,
 459                                            size_t* actual_size) {
 460   guarantee(false, "thread-local allocation buffers not supported");
 461   return NULL;
 462 }
 463 
 464 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
 465   assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
 466          "Should only be called at a safepoint or at start-up");
 467 
 468   ThreadLocalAllocStats stats;
 469 
 470   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next();) {
 471     BarrierSet::barrier_set()->make_parsable(thread);
 472     if (UseTLAB) {
 473       if (retire_tlabs) {
 474         thread->tlab().retire(&stats);
 475       } else {
 476         thread->tlab().make_parsable();
 477       }
 478     }
 479   }
 480 
 481   stats.publish();
 482 }
 483 
 484 void CollectedHeap::resize_all_tlabs() {
 485   assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
 486          "Should only resize tlabs at safepoint");
 487 
 488   if (UseTLAB && ResizeTLAB) {
 489     for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
 490       thread->tlab().resize();
 491     }
 492   }
 493 }
 494 
 495 void CollectedHeap::full_gc_dump(GCTimer* timer, bool before) {
 496   assert(timer != NULL, "timer is null");
 497   if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
 498     GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
 499     HeapDumper::dump_heap();
 500   }
 501 
 502   LogTarget(Trace, gc, classhisto) lt;
 503   if (lt.is_enabled()) {
 504     GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
 505     ResourceMark rm;
 506     LogStream ls(lt);
 507     VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
 508     inspector.doit();
 509   }
 510 }
 511 
 512 void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
 513   full_gc_dump(timer, true);
 514 }
 515 
 516 void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
 517   full_gc_dump(timer, false);
 518 }
 519 
 520 void CollectedHeap::initialize_reserved_region(const ReservedHeapSpace& rs) {
 521   // It is important to do this in a way such that concurrent readers can't
 522   // temporarily think something is in the heap.  (Seen this happen in asserts.)
 523   _reserved.set_word_size(0);
 524   _reserved.set_start((HeapWord*)rs.base());
 525   _reserved.set_end((HeapWord*)rs.end());
 526 }
 527 
 528 void CollectedHeap::post_initialize() {
 529   initialize_serviceability();
 530 }
 531 
 532 #ifndef PRODUCT
 533 
 534 bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
 535   // Access to count is not atomic; the value does not have to be exact.
 536   if (PromotionFailureALot) {
 537     const size_t gc_num = total_collections();
 538     const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
 539     if (elapsed_gcs >= PromotionFailureALotInterval) {
 540       // Test for unsigned arithmetic wrap-around.
 541       if (++*count >= PromotionFailureALotCount) {
 542         *count = 0;
 543         return true;
 544       }
 545     }
 546   }
 547   return false;
 548 }
 549 
 550 bool CollectedHeap::promotion_should_fail() {
 551   return promotion_should_fail(&_promotion_failure_alot_count);
 552 }
 553 
 554 void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
 555   if (PromotionFailureALot) {
 556     _promotion_failure_alot_gc_number = total_collections();
 557     *count = 0;
 558   }
 559 }
 560 
 561 void CollectedHeap::reset_promotion_should_fail() {
 562   reset_promotion_should_fail(&_promotion_failure_alot_count);
 563 }
 564 
 565 #endif  // #ifndef PRODUCT
 566 
 567 bool CollectedHeap::supports_object_pinning() const {
 568   return false;
 569 }
 570 
 571 oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
 572   ShouldNotReachHere();
 573   return NULL;
 574 }
 575 
 576 void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
 577   ShouldNotReachHere();
 578 }
 579 
 580 void CollectedHeap::deduplicate_string(oop str) {
 581   // Do nothing, unless overridden in subclass.
 582 }
 583 
 584 size_t CollectedHeap::obj_size(oop obj) const {
 585   return obj->size();
 586 }
 587 
 588 uint32_t CollectedHeap::hash_oop(oop obj) const {
 589   const uintptr_t addr = cast_from_oop<uintptr_t>(obj);
 590   return static_cast<uint32_t>(addr >> LogMinObjAlignment);
 591 }
--- EOF ---