rev 51152 : [mq]: gcbuildoptionspatch

   1 /*
   2  * Copyright (c) 2000, 2018, 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 "aot/aotLoader.hpp"
  27 #include "classfile/symbolTable.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "code/icBuffer.hpp"
  33 #include "gc/serial/defNewGeneration.hpp"
  34 #include "gc/shared/adaptiveSizePolicy.hpp"
  35 #include "gc/shared/cardTableBarrierSet.hpp"
  36 #include "gc/shared/cardTableRS.hpp"
  37 #include "gc/shared/collectedHeap.inline.hpp"
  38 #include "gc/shared/collectorCounters.hpp"
  39 #include "gc/shared/gcId.hpp"
  40 #include "gc/shared/gcLocker.hpp"
  41 #include "gc/shared/gcPolicyCounters.hpp"
  42 #include "gc/shared/gcTrace.hpp"
  43 #include "gc/shared/gcTraceTime.inline.hpp"
  44 #include "gc/shared/genCollectedHeap.hpp"
  45 #include "gc/shared/genOopClosures.inline.hpp"
  46 #include "gc/shared/generationSpec.hpp"
  47 #include "gc/shared/oopStorageParState.inline.hpp"
  48 #include "gc/shared/space.hpp"
  49 #include "gc/shared/strongRootsScope.hpp"
  50 #include "gc/shared/vmGCOperations.hpp"
  51 #include "gc/shared/weakProcessor.hpp"
  52 #include "gc/shared/workgroup.hpp"
  53 #include "memory/filemap.hpp"
  54 #include "memory/metaspaceCounters.hpp"
  55 #include "memory/resourceArea.hpp"
  56 #include "oops/oop.inline.hpp"
  57 #include "runtime/biasedLocking.hpp"
  58 #include "runtime/flags/flagSetting.hpp"
  59 #include "runtime/handles.hpp"
  60 #include "runtime/handles.inline.hpp"
  61 #include "runtime/java.hpp"
  62 #include "runtime/vmThread.hpp"
  63 #include "services/management.hpp"
  64 #include "services/memoryService.hpp"
  65 #include "utilities/debug.hpp"
  66 #include "utilities/formatBuffer.hpp"
  67 #include "utilities/macros.hpp"
  68 #include "utilities/stack.inline.hpp"
  69 #include "utilities/vmError.hpp"
  70 
  71 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
  72                                    Generation::Name young,
  73                                    Generation::Name old,
  74                                    const char* policy_counters_name) :
  75   CollectedHeap(),
  76   _rem_set(NULL),
  77   _young_gen_spec(new GenerationSpec(young,
  78                                      policy->initial_young_size(),
  79                                      policy->max_young_size(),
  80                                      policy->gen_alignment())),
  81   _old_gen_spec(new GenerationSpec(old,
  82                                    policy->initial_old_size(),
  83                                    policy->max_old_size(),
  84                                    policy->gen_alignment())),
  85   _gen_policy(policy),
  86   _soft_ref_gen_policy(),
  87   _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
  88   _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
  89   _full_collections_completed(0) {
  90 }
  91 
  92 jint GenCollectedHeap::initialize() {
  93   // While there are no constraints in the GC code that HeapWordSize
  94   // be any particular value, there are multiple other areas in the
  95   // system which believe this to be true (e.g. oop->object_size in some
  96   // cases incorrectly returns the size in wordSize units rather than
  97   // HeapWordSize).
  98   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
  99 
 100   // Allocate space for the heap.
 101 
 102   char* heap_address;
 103   ReservedSpace heap_rs;
 104 
 105   size_t heap_alignment = collector_policy()->heap_alignment();
 106 
 107   heap_address = allocate(heap_alignment, &heap_rs);
 108 
 109   if (!heap_rs.is_reserved()) {
 110     vm_shutdown_during_initialization(
 111       "Could not reserve enough space for object heap");
 112     return JNI_ENOMEM;
 113   }
 114 
 115   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
 116 
 117   _rem_set = create_rem_set(reserved_region());
 118   _rem_set->initialize();
 119   CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
 120   bs->initialize();
 121   BarrierSet::set_barrier_set(bs);
 122 
 123   ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
 124   _young_gen = _young_gen_spec->init(young_rs, rem_set());
 125   heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
 126 
 127   ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
 128   _old_gen = _old_gen_spec->init(old_rs, rem_set());
 129   clear_incremental_collection_failed();
 130 
 131   return JNI_OK;
 132 }
 133 
 134 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
 135   return new CardTableRS(reserved_region, false /* scan_concurrently */);
 136 }
 137 
 138 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
 139                                               size_t init_promo_size,
 140                                               size_t init_survivor_size) {
 141   const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
 142   _size_policy = new AdaptiveSizePolicy(init_eden_size,
 143                                         init_promo_size,
 144                                         init_survivor_size,
 145                                         max_gc_pause_sec,
 146                                         GCTimeRatio);
 147 }
 148 
 149 char* GenCollectedHeap::allocate(size_t alignment,
 150                                  ReservedSpace* heap_rs){
 151   // Now figure out the total size.
 152   const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
 153   assert(alignment % pageSize == 0, "Must be");
 154 
 155   // Check for overflow.
 156   size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
 157   if (total_reserved < _young_gen_spec->max_size()) {
 158     vm_exit_during_initialization("The size of the object heap + VM data exceeds "
 159                                   "the maximum representable size");
 160   }
 161   assert(total_reserved % alignment == 0,
 162          "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
 163          SIZE_FORMAT, total_reserved, alignment);
 164 
 165   *heap_rs = Universe::reserve_heap(total_reserved, alignment);
 166 
 167   os::trace_page_sizes("Heap",
 168                        collector_policy()->min_heap_byte_size(),
 169                        total_reserved,
 170                        alignment,
 171                        heap_rs->base(),
 172                        heap_rs->size());
 173 
 174   return heap_rs->base();
 175 }
 176 
 177 void GenCollectedHeap::post_initialize() {
 178   CollectedHeap::post_initialize();
 179   ref_processing_init();
 180 
 181   DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
 182 
 183   initialize_size_policy(def_new_gen->eden()->capacity(),
 184                          _old_gen->capacity(),
 185                          def_new_gen->from()->capacity());
 186 
 187 #if INCLUDE_SERIALGC
 188   MarkSweep::initialize();
 189 #endif
 190 }
 191 
 192 void GenCollectedHeap::ref_processing_init() {
 193   _young_gen->ref_processor_init();
 194   _old_gen->ref_processor_init();
 195 }
 196 
 197 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
 198   return _young_gen_spec;
 199 }
 200 
 201 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
 202   return _old_gen_spec;
 203 }
 204 
 205 size_t GenCollectedHeap::capacity() const {
 206   return _young_gen->capacity() + _old_gen->capacity();
 207 }
 208 
 209 size_t GenCollectedHeap::used() const {
 210   return _young_gen->used() + _old_gen->used();
 211 }
 212 
 213 void GenCollectedHeap::save_used_regions() {
 214   _old_gen->save_used_region();
 215   _young_gen->save_used_region();
 216 }
 217 
 218 size_t GenCollectedHeap::max_capacity() const {
 219   return _young_gen->max_capacity() + _old_gen->max_capacity();
 220 }
 221 
 222 // Update the _full_collections_completed counter
 223 // at the end of a stop-world full GC.
 224 unsigned int GenCollectedHeap::update_full_collections_completed() {
 225   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 226   assert(_full_collections_completed <= _total_full_collections,
 227          "Can't complete more collections than were started");
 228   _full_collections_completed = _total_full_collections;
 229   ml.notify_all();
 230   return _full_collections_completed;
 231 }
 232 
 233 // Update the _full_collections_completed counter, as appropriate,
 234 // at the end of a concurrent GC cycle. Note the conditional update
 235 // below to allow this method to be called by a concurrent collector
 236 // without synchronizing in any manner with the VM thread (which
 237 // may already have initiated a STW full collection "concurrently").
 238 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 239   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 240   assert((_full_collections_completed <= _total_full_collections) &&
 241          (count <= _total_full_collections),
 242          "Can't complete more collections than were started");
 243   if (count > _full_collections_completed) {
 244     _full_collections_completed = count;
 245     ml.notify_all();
 246   }
 247   return _full_collections_completed;
 248 }
 249 
 250 // Return true if any of the following is true:
 251 // . the allocation won't fit into the current young gen heap
 252 // . gc locker is occupied (jni critical section)
 253 // . heap memory is tight -- the most recent previous collection
 254 //   was a full collection because a partial collection (would
 255 //   have) failed and is likely to fail again
 256 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
 257   size_t young_capacity = _young_gen->capacity_before_gc();
 258   return    (word_size > heap_word_size(young_capacity))
 259          || GCLocker::is_active_and_needs_gc()
 260          || incremental_collection_failed();
 261 }
 262 
 263 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool   is_tlab) {
 264   HeapWord* result = NULL;
 265   if (_old_gen->should_allocate(size, is_tlab)) {
 266     result = _old_gen->expand_and_allocate(size, is_tlab);
 267   }
 268   if (result == NULL) {
 269     if (_young_gen->should_allocate(size, is_tlab)) {
 270       result = _young_gen->expand_and_allocate(size, is_tlab);
 271     }
 272   }
 273   assert(result == NULL || is_in_reserved(result), "result not in heap");
 274   return result;
 275 }
 276 
 277 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
 278                                               bool is_tlab,
 279                                               bool* gc_overhead_limit_was_exceeded) {
 280   // In general gc_overhead_limit_was_exceeded should be false so
 281   // set it so here and reset it to true only if the gc time
 282   // limit is being exceeded as checked below.
 283   *gc_overhead_limit_was_exceeded = false;
 284 
 285   HeapWord* result = NULL;
 286 
 287   // Loop until the allocation is satisfied, or unsatisfied after GC.
 288   for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
 289     HandleMark hm; // Discard any handles allocated in each iteration.
 290 
 291     // First allocation attempt is lock-free.
 292     Generation *young = _young_gen;
 293     assert(young->supports_inline_contig_alloc(),
 294       "Otherwise, must do alloc within heap lock");
 295     if (young->should_allocate(size, is_tlab)) {
 296       result = young->par_allocate(size, is_tlab);
 297       if (result != NULL) {
 298         assert(is_in_reserved(result), "result not in heap");
 299         return result;
 300       }
 301     }
 302     uint gc_count_before;  // Read inside the Heap_lock locked region.
 303     {
 304       MutexLocker ml(Heap_lock);
 305       log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
 306       // Note that only large objects get a shot at being
 307       // allocated in later generations.
 308       bool first_only = !should_try_older_generation_allocation(size);
 309 
 310       result = attempt_allocation(size, is_tlab, first_only);
 311       if (result != NULL) {
 312         assert(is_in_reserved(result), "result not in heap");
 313         return result;
 314       }
 315 
 316       if (GCLocker::is_active_and_needs_gc()) {
 317         if (is_tlab) {
 318           return NULL;  // Caller will retry allocating individual object.
 319         }
 320         if (!is_maximal_no_gc()) {
 321           // Try and expand heap to satisfy request.
 322           result = expand_heap_and_allocate(size, is_tlab);
 323           // Result could be null if we are out of space.
 324           if (result != NULL) {
 325             return result;
 326           }
 327         }
 328 
 329         if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
 330           return NULL; // We didn't get to do a GC and we didn't get any memory.
 331         }
 332 
 333         // If this thread is not in a jni critical section, we stall
 334         // the requestor until the critical section has cleared and
 335         // GC allowed. When the critical section clears, a GC is
 336         // initiated by the last thread exiting the critical section; so
 337         // we retry the allocation sequence from the beginning of the loop,
 338         // rather than causing more, now probably unnecessary, GC attempts.
 339         JavaThread* jthr = JavaThread::current();
 340         if (!jthr->in_critical()) {
 341           MutexUnlocker mul(Heap_lock);
 342           // Wait for JNI critical section to be exited
 343           GCLocker::stall_until_clear();
 344           gclocker_stalled_count += 1;
 345           continue;
 346         } else {
 347           if (CheckJNICalls) {
 348             fatal("Possible deadlock due to allocating while"
 349                   " in jni critical section");
 350           }
 351           return NULL;
 352         }
 353       }
 354 
 355       // Read the gc count while the heap lock is held.
 356       gc_count_before = total_collections();
 357     }
 358 
 359     VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
 360     VMThread::execute(&op);
 361     if (op.prologue_succeeded()) {
 362       result = op.result();
 363       if (op.gc_locked()) {
 364          assert(result == NULL, "must be NULL if gc_locked() is true");
 365          continue;  // Retry and/or stall as necessary.
 366       }
 367 
 368       // Allocation has failed and a collection
 369       // has been done.  If the gc time limit was exceeded the
 370       // this time, return NULL so that an out-of-memory
 371       // will be thrown.  Clear gc_overhead_limit_exceeded
 372       // so that the overhead exceeded does not persist.
 373 
 374       const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
 375       const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
 376 
 377       if (limit_exceeded && softrefs_clear) {
 378         *gc_overhead_limit_was_exceeded = true;
 379         size_policy()->set_gc_overhead_limit_exceeded(false);
 380         if (op.result() != NULL) {
 381           CollectedHeap::fill_with_object(op.result(), size);
 382         }
 383         return NULL;
 384       }
 385       assert(result == NULL || is_in_reserved(result),
 386              "result not in heap");
 387       return result;
 388     }
 389 
 390     // Give a warning if we seem to be looping forever.
 391     if ((QueuedAllocationWarningCount > 0) &&
 392         (try_count % QueuedAllocationWarningCount == 0)) {
 393           log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
 394                                 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
 395     }
 396   }
 397 }
 398 
 399 #ifndef PRODUCT
 400 // Override of memory state checking method in CollectedHeap:
 401 // Some collectors (CMS for example) can't have badHeapWordVal written
 402 // in the first two words of an object. (For instance , in the case of
 403 // CMS these words hold state used to synchronize between certain
 404 // (concurrent) GC steps and direct allocating mutators.)
 405 // The skip_header_HeapWords() method below, allows us to skip
 406 // over the requisite number of HeapWord's. Note that (for
 407 // generational collectors) this means that those many words are
 408 // skipped in each object, irrespective of the generation in which
 409 // that object lives. The resultant loss of precision seems to be
 410 // harmless and the pain of avoiding that imprecision appears somewhat
 411 // higher than we are prepared to pay for such rudimentary debugging
 412 // support.
 413 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 414                                                          size_t size) {
 415   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 416     // We are asked to check a size in HeapWords,
 417     // but the memory is mangled in juint words.
 418     juint* start = (juint*) (addr + skip_header_HeapWords());
 419     juint* end   = (juint*) (addr + size);
 420     for (juint* slot = start; slot < end; slot += 1) {
 421       assert(*slot == badHeapWordVal,
 422              "Found non badHeapWordValue in pre-allocation check");
 423     }
 424   }
 425 }
 426 #endif
 427 
 428 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 429                                                bool is_tlab,
 430                                                bool first_only) {
 431   HeapWord* res = NULL;
 432 
 433   if (_young_gen->should_allocate(size, is_tlab)) {
 434     res = _young_gen->allocate(size, is_tlab);
 435     if (res != NULL || first_only) {
 436       return res;
 437     }
 438   }
 439 
 440   if (_old_gen->should_allocate(size, is_tlab)) {
 441     res = _old_gen->allocate(size, is_tlab);
 442   }
 443 
 444   return res;
 445 }
 446 
 447 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 448                                          bool* gc_overhead_limit_was_exceeded) {
 449   return mem_allocate_work(size,
 450                            false /* is_tlab */,
 451                            gc_overhead_limit_was_exceeded);
 452 }
 453 
 454 bool GenCollectedHeap::must_clear_all_soft_refs() {
 455   return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
 456          _gc_cause == GCCause::_wb_full_gc;
 457 }
 458 
 459 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
 460                                           bool is_tlab, bool run_verification, bool clear_soft_refs,
 461                                           bool restore_marks_for_biased_locking) {
 462   FormatBuffer<> title("Collect gen: %s", gen->short_name());
 463   GCTraceTime(Trace, gc, phases) t1(title);
 464   TraceCollectorStats tcs(gen->counters());
 465   TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
 466 
 467   gen->stat_record()->invocations++;
 468   gen->stat_record()->accumulated_time.start();
 469 
 470   // Must be done anew before each collection because
 471   // a previous collection will do mangling and will
 472   // change top of some spaces.
 473   record_gen_tops_before_GC();
 474 
 475   log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
 476 
 477   if (run_verification && VerifyBeforeGC) {
 478     HandleMark hm;  // Discard invalid handles created during verification
 479     Universe::verify("Before GC");
 480   }
 481   COMPILER2_PRESENT(DerivedPointerTable::clear());
 482 
 483   if (restore_marks_for_biased_locking) {
 484     // We perform this mark word preservation work lazily
 485     // because it's only at this point that we know whether we
 486     // absolutely have to do it; we want to avoid doing it for
 487     // scavenge-only collections where it's unnecessary
 488     BiasedLocking::preserve_marks();
 489   }
 490 
 491   // Do collection work
 492   {
 493     // Note on ref discovery: For what appear to be historical reasons,
 494     // GCH enables and disabled (by enqueing) refs discovery.
 495     // In the future this should be moved into the generation's
 496     // collect method so that ref discovery and enqueueing concerns
 497     // are local to a generation. The collect method could return
 498     // an appropriate indication in the case that notification on
 499     // the ref lock was needed. This will make the treatment of
 500     // weak refs more uniform (and indeed remove such concerns
 501     // from GCH). XXX
 502 
 503     HandleMark hm;  // Discard invalid handles created during gc
 504     save_marks();   // save marks for all gens
 505     // We want to discover references, but not process them yet.
 506     // This mode is disabled in process_discovered_references if the
 507     // generation does some collection work, or in
 508     // enqueue_discovered_references if the generation returns
 509     // without doing any work.
 510     ReferenceProcessor* rp = gen->ref_processor();
 511     // If the discovery of ("weak") refs in this generation is
 512     // atomic wrt other collectors in this configuration, we
 513     // are guaranteed to have empty discovered ref lists.
 514     if (rp->discovery_is_atomic()) {
 515       rp->enable_discovery();
 516       rp->setup_policy(clear_soft_refs);
 517     } else {
 518       // collect() below will enable discovery as appropriate
 519     }
 520     gen->collect(full, clear_soft_refs, size, is_tlab);
 521     if (!rp->enqueuing_is_done()) {
 522       rp->disable_discovery();
 523     } else {
 524       rp->set_enqueuing_is_done(false);
 525     }
 526     rp->verify_no_references_recorded();
 527   }
 528 
 529   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 530 
 531   gen->stat_record()->accumulated_time.stop();
 532 
 533   update_gc_stats(gen, full);
 534 
 535   if (run_verification && VerifyAfterGC) {
 536     HandleMark hm;  // Discard invalid handles created during verification
 537     Universe::verify("After GC");
 538   }
 539 }
 540 
 541 void GenCollectedHeap::do_collection(bool           full,
 542                                      bool           clear_all_soft_refs,
 543                                      size_t         size,
 544                                      bool           is_tlab,
 545                                      GenerationType max_generation) {
 546   ResourceMark rm;
 547   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 548 
 549   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 550   assert(my_thread->is_VM_thread() ||
 551          my_thread->is_ConcurrentGC_thread(),
 552          "incorrect thread type capability");
 553   assert(Heap_lock->is_locked(),
 554          "the requesting thread should have the Heap_lock");
 555   guarantee(!is_gc_active(), "collection is not reentrant");
 556 
 557   if (GCLocker::check_active_before_gc()) {
 558     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 559   }
 560 
 561   GCIdMark gc_id_mark;
 562 
 563   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 564                           soft_ref_policy()->should_clear_all_soft_refs();
 565 
 566   ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
 567 
 568   const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
 569 
 570   print_heap_before_gc();
 571 
 572   {
 573     FlagSetting fl(_is_gc_active, true);
 574 
 575     bool complete = full && (max_generation == OldGen);
 576     bool old_collects_young = complete && !ScavengeBeforeFullGC;
 577     bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
 578 
 579     FormatBuffer<> gc_string("%s", "Pause ");
 580     if (do_young_collection) {
 581       gc_string.append("Young");
 582     } else {
 583       gc_string.append("Full");
 584     }
 585 
 586     GCTraceCPUTime tcpu;
 587     GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
 588 
 589     gc_prologue(complete);
 590     increment_total_collections(complete);
 591 
 592     size_t young_prev_used = _young_gen->used();
 593     size_t old_prev_used = _old_gen->used();
 594 
 595     bool run_verification = total_collections() >= VerifyGCStartAt;
 596 
 597     bool prepared_for_verification = false;
 598     bool collected_old = false;
 599 
 600     if (do_young_collection) {
 601       if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
 602         prepare_for_verify();
 603         prepared_for_verification = true;
 604       }
 605 
 606       collect_generation(_young_gen,
 607                          full,
 608                          size,
 609                          is_tlab,
 610                          run_verification && VerifyGCLevel <= 0,
 611                          do_clear_all_soft_refs,
 612                          false);
 613 
 614       if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
 615           size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
 616         // Allocation request was met by young GC.
 617         size = 0;
 618       }
 619     }
 620 
 621     bool must_restore_marks_for_biased_locking = false;
 622 
 623     if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
 624       if (!complete) {
 625         // The full_collections increment was missed above.
 626         increment_total_full_collections();
 627       }
 628 
 629       if (!prepared_for_verification && run_verification &&
 630           VerifyGCLevel <= 1 && VerifyBeforeGC) {
 631         prepare_for_verify();
 632       }
 633 
 634       if (do_young_collection) {
 635         // We did a young GC. Need a new GC id for the old GC.
 636         GCIdMark gc_id_mark;
 637         GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
 638         collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
 639       } else {
 640         // No young GC done. Use the same GC id as was set up earlier in this method.
 641         collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
 642       }
 643 
 644       must_restore_marks_for_biased_locking = true;
 645       collected_old = true;
 646     }
 647 
 648     // Update "complete" boolean wrt what actually transpired --
 649     // for instance, a promotion failure could have led to
 650     // a whole heap collection.
 651     complete = complete || collected_old;
 652 
 653     print_heap_change(young_prev_used, old_prev_used);
 654     MetaspaceUtils::print_metaspace_change(metadata_prev_used);
 655 
 656     // Adjust generation sizes.
 657     if (collected_old) {
 658       _old_gen->compute_new_size();
 659     }
 660     _young_gen->compute_new_size();
 661 
 662     if (complete) {
 663       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 664       ClassLoaderDataGraph::purge();
 665       MetaspaceUtils::verify_metrics();
 666       // Resize the metaspace capacity after full collections
 667       MetaspaceGC::compute_new_size();
 668       update_full_collections_completed();
 669     }
 670 
 671     // Track memory usage and detect low memory after GC finishes
 672     MemoryService::track_memory_usage();
 673 
 674     gc_epilogue(complete);
 675 
 676     if (must_restore_marks_for_biased_locking) {
 677       BiasedLocking::restore_marks();
 678     }
 679   }
 680 
 681   print_heap_after_gc();
 682 
 683 #ifdef TRACESPINNING
 684   ParallelTaskTerminator::print_termination_counts();
 685 #endif
 686 }
 687 
 688 void GenCollectedHeap::register_nmethod(nmethod* nm) {
 689   CodeCache::register_scavenge_root_nmethod(nm);
 690 }
 691 
 692 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
 693   CodeCache::verify_scavenge_root_nmethod(nm);
 694 }
 695 
 696 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 697   GCCauseSetter x(this, GCCause::_allocation_failure);
 698   HeapWord* result = NULL;
 699 
 700   assert(size != 0, "Precondition violated");
 701   if (GCLocker::is_active_and_needs_gc()) {
 702     // GC locker is active; instead of a collection we will attempt
 703     // to expand the heap, if there's room for expansion.
 704     if (!is_maximal_no_gc()) {
 705       result = expand_heap_and_allocate(size, is_tlab);
 706     }
 707     return result;   // Could be null if we are out of space.
 708   } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
 709     // Do an incremental collection.
 710     do_collection(false,                     // full
 711                   false,                     // clear_all_soft_refs
 712                   size,                      // size
 713                   is_tlab,                   // is_tlab
 714                   GenCollectedHeap::OldGen); // max_generation
 715   } else {
 716     log_trace(gc)(" :: Trying full because partial may fail :: ");
 717     // Try a full collection; see delta for bug id 6266275
 718     // for the original code and why this has been simplified
 719     // with from-space allocation criteria modified and
 720     // such allocation moved out of the safepoint path.
 721     do_collection(true,                      // full
 722                   false,                     // clear_all_soft_refs
 723                   size,                      // size
 724                   is_tlab,                   // is_tlab
 725                   GenCollectedHeap::OldGen); // max_generation
 726   }
 727 
 728   result = attempt_allocation(size, is_tlab, false /*first_only*/);
 729 
 730   if (result != NULL) {
 731     assert(is_in_reserved(result), "result not in heap");
 732     return result;
 733   }
 734 
 735   // OK, collection failed, try expansion.
 736   result = expand_heap_and_allocate(size, is_tlab);
 737   if (result != NULL) {
 738     return result;
 739   }
 740 
 741   // If we reach this point, we're really out of memory. Try every trick
 742   // we can to reclaim memory. Force collection of soft references. Force
 743   // a complete compaction of the heap. Any additional methods for finding
 744   // free memory should be here, especially if they are expensive. If this
 745   // attempt fails, an OOM exception will be thrown.
 746   {
 747     UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
 748 
 749     do_collection(true,                      // full
 750                   true,                      // clear_all_soft_refs
 751                   size,                      // size
 752                   is_tlab,                   // is_tlab
 753                   GenCollectedHeap::OldGen); // max_generation
 754   }
 755 
 756   result = attempt_allocation(size, is_tlab, false /* first_only */);
 757   if (result != NULL) {
 758     assert(is_in_reserved(result), "result not in heap");
 759     return result;
 760   }
 761 
 762   assert(!soft_ref_policy()->should_clear_all_soft_refs(),
 763     "Flag should have been handled and cleared prior to this point");
 764 
 765   // What else?  We might try synchronous finalization later.  If the total
 766   // space available is large enough for the allocation, then a more
 767   // complete compaction phase than we've tried so far might be
 768   // appropriate.
 769   return NULL;
 770 }
 771 
 772 #ifdef ASSERT
 773 class AssertNonScavengableClosure: public OopClosure {
 774 public:
 775   virtual void do_oop(oop* p) {
 776     assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
 777       "Referent should not be scavengable.");  }
 778   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 779 };
 780 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 781 #endif
 782 
 783 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
 784                                      ScanningOption so,
 785                                      OopClosure* strong_roots,
 786                                      CLDClosure* strong_cld_closure,
 787                                      CLDClosure* weak_cld_closure,
 788                                      CodeBlobToOopClosure* code_roots) {
 789   // General roots.
 790   assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
 791   assert(code_roots != NULL, "code root closure should always be set");
 792   // _n_termination for _process_strong_tasks should be set up stream
 793   // in a method not running in a GC worker.  Otherwise the GC worker
 794   // could be trying to change the termination condition while the task
 795   // is executing in another GC worker.
 796 
 797   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
 798     ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
 799   }
 800 
 801   // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
 802   CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
 803 
 804   bool is_par = scope->n_threads() > 1;
 805   Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
 806 
 807   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
 808     Universe::oops_do(strong_roots);
 809   }
 810   // Global (strong) JNI handles
 811   if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
 812     JNIHandles::oops_do(strong_roots);
 813   }
 814 
 815   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
 816     ObjectSynchronizer::oops_do(strong_roots);
 817   }
 818   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
 819     Management::oops_do(strong_roots);
 820   }
 821   if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
 822     JvmtiExport::oops_do(strong_roots);
 823   }
 824   if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
 825     AOTLoader::oops_do(strong_roots);
 826   }
 827 
 828   if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
 829     SystemDictionary::oops_do(strong_roots);
 830   }
 831 
 832   if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
 833     if (so & SO_ScavengeCodeCache) {
 834       assert(code_roots != NULL, "must supply closure for code cache");
 835 
 836       // We only visit parts of the CodeCache when scavenging.
 837       CodeCache::scavenge_root_nmethods_do(code_roots);
 838     }
 839     if (so & SO_AllCodeCache) {
 840       assert(code_roots != NULL, "must supply closure for code cache");
 841 
 842       // CMSCollector uses this to do intermediate-strength collections.
 843       // We scan the entire code cache, since CodeCache::do_unloading is not called.
 844       CodeCache::blobs_do(code_roots);
 845     }
 846     // Verify that the code cache contents are not subject to
 847     // movement by a scavenging collection.
 848     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
 849     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
 850   }
 851 }
 852 
 853 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
 854                                                   OopClosure* root_closure,
 855                                                   OopStorage::ParState<false, false>* par_state_string) {
 856   assert(root_closure != NULL, "Must be set");
 857   // All threads execute the following. A specific chunk of buckets
 858   // from the StringTable are the individual tasks.
 859 
 860   // Either we should be single threaded or have a ParState
 861   assert((scope->n_threads() <= 1) || par_state_string != NULL, "Parallel but no ParState");
 862 
 863   if (scope->n_threads() > 1) {
 864     StringTable::possibly_parallel_oops_do(par_state_string, root_closure);
 865   } else {
 866     StringTable::oops_do(root_closure);
 867   }
 868 }
 869 
 870 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
 871                                            OopsInGenClosure* root_closure,
 872                                            OopsInGenClosure* old_gen_closure,
 873                                            CLDClosure* cld_closure,
 874                                            OopStorage::ParState<false, false>* par_state_string) {
 875   MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
 876 
 877   process_roots(scope, SO_ScavengeCodeCache, root_closure,
 878                 cld_closure, cld_closure, &mark_code_closure);
 879   process_string_table_roots(scope, root_closure, par_state_string);
 880 
 881   if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 882     root_closure->reset_generation();
 883   }
 884 
 885   // When collection is parallel, all threads get to cooperate to do
 886   // old generation scanning.
 887   old_gen_closure->set_generation(_old_gen);
 888   rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
 889   old_gen_closure->reset_generation();
 890 
 891   _process_strong_tasks->all_tasks_completed(scope->n_threads());
 892 }
 893 
 894 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
 895                                           bool is_adjust_phase,
 896                                           ScanningOption so,
 897                                           bool only_strong_roots,
 898                                           OopsInGenClosure* root_closure,
 899                                           CLDClosure* cld_closure,
 900                                           OopStorage::ParState<false, false>* par_state_string) {
 901   MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
 902   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
 903 
 904   process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
 905   if (is_adjust_phase) {
 906     // We never treat the string table as roots during marking
 907     // for the full gc, so we only need to process it during
 908     // the adjust phase.
 909     process_string_table_roots(scope, root_closure, par_state_string);
 910   }
 911 
 912   _process_strong_tasks->all_tasks_completed(scope->n_threads());
 913 }
 914 
 915 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 916   WeakProcessor::oops_do(root_closure);
 917   _young_gen->ref_processor()->weak_oops_do(root_closure);
 918   _old_gen->ref_processor()->weak_oops_do(root_closure);
 919 }
 920 
 921 bool GenCollectedHeap::no_allocs_since_save_marks() {
 922   return _young_gen->no_allocs_since_save_marks() &&
 923          _old_gen->no_allocs_since_save_marks();
 924 }
 925 
 926 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 927   return _young_gen->supports_inline_contig_alloc();
 928 }
 929 
 930 HeapWord* volatile* GenCollectedHeap::top_addr() const {
 931   return _young_gen->top_addr();
 932 }
 933 
 934 HeapWord** GenCollectedHeap::end_addr() const {
 935   return _young_gen->end_addr();
 936 }
 937 
 938 // public collection interfaces
 939 
 940 void GenCollectedHeap::collect(GCCause::Cause cause) {
 941   if (cause == GCCause::_wb_young_gc) {
 942     // Young collection for the WhiteBox API.
 943     collect(cause, YoungGen);
 944   } else {
 945 #ifdef ASSERT
 946   if (cause == GCCause::_scavenge_alot) {
 947     // Young collection only.
 948     collect(cause, YoungGen);
 949   } else {
 950     // Stop-the-world full collection.
 951     collect(cause, OldGen);
 952   }
 953 #else
 954     // Stop-the-world full collection.
 955     collect(cause, OldGen);
 956 #endif
 957   }
 958 }
 959 
 960 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
 961   // The caller doesn't have the Heap_lock
 962   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 963   MutexLocker ml(Heap_lock);
 964   collect_locked(cause, max_generation);
 965 }
 966 
 967 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 968   // The caller has the Heap_lock
 969   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 970   collect_locked(cause, OldGen);
 971 }
 972 
 973 // this is the private collection interface
 974 // The Heap_lock is expected to be held on entry.
 975 
 976 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
 977   // Read the GC count while holding the Heap_lock
 978   unsigned int gc_count_before      = total_collections();
 979   unsigned int full_gc_count_before = total_full_collections();
 980   {
 981     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 982     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 983                          cause, max_generation);
 984     VMThread::execute(&op);
 985   }
 986 }
 987 
 988 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 989    do_full_collection(clear_all_soft_refs, OldGen);
 990 }
 991 
 992 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 993                                           GenerationType last_generation) {
 994   GenerationType local_last_generation;
 995   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 996       gc_cause() == GCCause::_gc_locker) {
 997     local_last_generation = YoungGen;
 998   } else {
 999     local_last_generation = last_generation;
1000   }
1001 
1002   do_collection(true,                   // full
1003                 clear_all_soft_refs,    // clear_all_soft_refs
1004                 0,                      // size
1005                 false,                  // is_tlab
1006                 local_last_generation); // last_generation
1007   // Hack XXX FIX ME !!!
1008   // A scavenge may not have been attempted, or may have
1009   // been attempted and failed, because the old gen was too full
1010   if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1011       incremental_collection_will_fail(false /* don't consult_young */)) {
1012     log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1013     // This time allow the old gen to be collected as well
1014     do_collection(true,                // full
1015                   clear_all_soft_refs, // clear_all_soft_refs
1016                   0,                   // size
1017                   false,               // is_tlab
1018                   OldGen);             // last_generation
1019   }
1020 }
1021 
1022 bool GenCollectedHeap::is_in_young(oop p) {
1023   bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1024   assert(result == _young_gen->is_in_reserved(p),
1025          "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1026   return result;
1027 }
1028 
1029 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1030 bool GenCollectedHeap::is_in(const void* p) const {
1031   return _young_gen->is_in(p) || _old_gen->is_in(p);
1032 }
1033 
1034 #ifdef ASSERT
1035 // Don't implement this by using is_in_young().  This method is used
1036 // in some cases to check that is_in_young() is correct.
1037 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1038   assert(is_in_reserved(p) || p == NULL,
1039     "Does not work if address is non-null and outside of the heap");
1040   return p < _young_gen->reserved().end() && p != NULL;
1041 }
1042 #endif
1043 
1044 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
1045   _young_gen->oop_iterate(cl);
1046   _old_gen->oop_iterate(cl);
1047 }
1048 
1049 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1050   _young_gen->object_iterate(cl);
1051   _old_gen->object_iterate(cl);
1052 }
1053 
1054 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1055   _young_gen->safe_object_iterate(cl);
1056   _old_gen->safe_object_iterate(cl);
1057 }
1058 
1059 Space* GenCollectedHeap::space_containing(const void* addr) const {
1060   Space* res = _young_gen->space_containing(addr);
1061   if (res != NULL) {
1062     return res;
1063   }
1064   res = _old_gen->space_containing(addr);
1065   assert(res != NULL, "Could not find containing space");
1066   return res;
1067 }
1068 
1069 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1070   assert(is_in_reserved(addr), "block_start of address outside of heap");
1071   if (_young_gen->is_in_reserved(addr)) {
1072     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1073     return _young_gen->block_start(addr);
1074   }
1075 
1076   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1077   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1078   return _old_gen->block_start(addr);
1079 }
1080 
1081 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1082   assert(is_in_reserved(addr), "block_size of address outside of heap");
1083   if (_young_gen->is_in_reserved(addr)) {
1084     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1085     return _young_gen->block_size(addr);
1086   }
1087 
1088   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1089   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1090   return _old_gen->block_size(addr);
1091 }
1092 
1093 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1094   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1095   assert(block_start(addr) == addr, "addr must be a block start");
1096   if (_young_gen->is_in_reserved(addr)) {
1097     return _young_gen->block_is_obj(addr);
1098   }
1099 
1100   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1101   return _old_gen->block_is_obj(addr);
1102 }
1103 
1104 bool GenCollectedHeap::supports_tlab_allocation() const {
1105   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1106   return _young_gen->supports_tlab_allocation();
1107 }
1108 
1109 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1110   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1111   if (_young_gen->supports_tlab_allocation()) {
1112     return _young_gen->tlab_capacity();
1113   }
1114   return 0;
1115 }
1116 
1117 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1118   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1119   if (_young_gen->supports_tlab_allocation()) {
1120     return _young_gen->tlab_used();
1121   }
1122   return 0;
1123 }
1124 
1125 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1126   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1127   if (_young_gen->supports_tlab_allocation()) {
1128     return _young_gen->unsafe_max_tlab_alloc();
1129   }
1130   return 0;
1131 }
1132 
1133 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1134                                               size_t requested_size,
1135                                               size_t* actual_size) {
1136   bool gc_overhead_limit_was_exceeded;
1137   HeapWord* result = mem_allocate_work(requested_size /* size */,
1138                                        true /* is_tlab */,
1139                                        &gc_overhead_limit_was_exceeded);
1140   if (result != NULL) {
1141     *actual_size = requested_size;
1142   }
1143 
1144   return result;
1145 }
1146 
1147 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
1148 // from the list headed by "*prev_ptr".
1149 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1150   bool first = true;
1151   size_t min_size = 0;   // "first" makes this conceptually infinite.
1152   ScratchBlock **smallest_ptr, *smallest;
1153   ScratchBlock  *cur = *prev_ptr;
1154   while (cur) {
1155     assert(*prev_ptr == cur, "just checking");
1156     if (first || cur->num_words < min_size) {
1157       smallest_ptr = prev_ptr;
1158       smallest     = cur;
1159       min_size     = smallest->num_words;
1160       first        = false;
1161     }
1162     prev_ptr = &cur->next;
1163     cur     =  cur->next;
1164   }
1165   smallest      = *smallest_ptr;
1166   *smallest_ptr = smallest->next;
1167   return smallest;
1168 }
1169 
1170 // Sort the scratch block list headed by res into decreasing size order,
1171 // and set "res" to the result.
1172 static void sort_scratch_list(ScratchBlock*& list) {
1173   ScratchBlock* sorted = NULL;
1174   ScratchBlock* unsorted = list;
1175   while (unsorted) {
1176     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1177     smallest->next  = sorted;
1178     sorted          = smallest;
1179   }
1180   list = sorted;
1181 }
1182 
1183 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1184                                                size_t max_alloc_words) {
1185   ScratchBlock* res = NULL;
1186   _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1187   _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1188   sort_scratch_list(res);
1189   return res;
1190 }
1191 
1192 void GenCollectedHeap::release_scratch() {
1193   _young_gen->reset_scratch();
1194   _old_gen->reset_scratch();
1195 }
1196 
1197 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1198   void do_generation(Generation* gen) {
1199     gen->prepare_for_verify();
1200   }
1201 };
1202 
1203 void GenCollectedHeap::prepare_for_verify() {
1204   ensure_parsability(false);        // no need to retire TLABs
1205   GenPrepareForVerifyClosure blk;
1206   generation_iterate(&blk, false);
1207 }
1208 
1209 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1210                                           bool old_to_young) {
1211   if (old_to_young) {
1212     cl->do_generation(_old_gen);
1213     cl->do_generation(_young_gen);
1214   } else {
1215     cl->do_generation(_young_gen);
1216     cl->do_generation(_old_gen);
1217   }
1218 }
1219 
1220 bool GenCollectedHeap::is_maximal_no_gc() const {
1221   return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1222 }
1223 
1224 void GenCollectedHeap::save_marks() {
1225   _young_gen->save_marks();
1226   _old_gen->save_marks();
1227 }
1228 
1229 GenCollectedHeap* GenCollectedHeap::heap() {
1230   CollectedHeap* heap = Universe::heap();
1231   assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1232   assert(heap->kind() == CollectedHeap::Serial ||
1233          heap->kind() == CollectedHeap::CMS, "Invalid name");
1234   return (GenCollectedHeap*) heap;
1235 }
1236 
1237 #if INCLUDE_SERIALGC
1238 void GenCollectedHeap::prepare_for_compaction() {
1239   // Start by compacting into same gen.
1240   CompactPoint cp(_old_gen);
1241   _old_gen->prepare_for_compaction(&cp);
1242   _young_gen->prepare_for_compaction(&cp);
1243 }
1244 #endif // INCLUDE_SERIALGC
1245 
1246 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1247   log_debug(gc, verify)("%s", _old_gen->name());
1248   _old_gen->verify();
1249 
1250   log_debug(gc, verify)("%s", _old_gen->name());
1251   _young_gen->verify();
1252 
1253   log_debug(gc, verify)("RemSet");
1254   rem_set()->verify();
1255 }
1256 
1257 void GenCollectedHeap::print_on(outputStream* st) const {
1258   _young_gen->print_on(st);
1259   _old_gen->print_on(st);
1260   MetaspaceUtils::print_on(st);
1261 }
1262 
1263 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1264 }
1265 
1266 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1267 }
1268 
1269 void GenCollectedHeap::print_tracing_info() const {
1270   if (log_is_enabled(Debug, gc, heap, exit)) {
1271     LogStreamHandle(Debug, gc, heap, exit) lsh;
1272     _young_gen->print_summary_info_on(&lsh);
1273     _old_gen->print_summary_info_on(&lsh);
1274   }
1275 }
1276 
1277 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1278   log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K("  SIZE_FORMAT "K)",
1279                      _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1280   log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K("  SIZE_FORMAT "K)",
1281                      _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1282 }
1283 
1284 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1285  private:
1286   bool _full;
1287  public:
1288   void do_generation(Generation* gen) {
1289     gen->gc_prologue(_full);
1290   }
1291   GenGCPrologueClosure(bool full) : _full(full) {};
1292 };
1293 
1294 void GenCollectedHeap::gc_prologue(bool full) {
1295   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1296 
1297   // Fill TLAB's and such
1298   CollectedHeap::accumulate_statistics_all_tlabs();
1299   ensure_parsability(true);   // retire TLABs
1300 
1301   // Walk generations
1302   GenGCPrologueClosure blk(full);
1303   generation_iterate(&blk, false);  // not old-to-young.
1304 };
1305 
1306 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1307  private:
1308   bool _full;
1309  public:
1310   void do_generation(Generation* gen) {
1311     gen->gc_epilogue(_full);
1312   }
1313   GenGCEpilogueClosure(bool full) : _full(full) {};
1314 };
1315 
1316 void GenCollectedHeap::gc_epilogue(bool full) {
1317 #if COMPILER2_OR_JVMCI
1318   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1319   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1320   guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1321 #endif // COMPILER2_OR_JVMCI
1322 
1323   resize_all_tlabs();
1324 
1325   GenGCEpilogueClosure blk(full);
1326   generation_iterate(&blk, false);  // not old-to-young.
1327 
1328   if (!CleanChunkPoolAsync) {
1329     Chunk::clean_chunk_pool();
1330   }
1331 
1332   MetaspaceCounters::update_performance_counters();
1333   CompressedClassSpaceCounters::update_performance_counters();
1334 };
1335 
1336 #ifndef PRODUCT
1337 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1338  private:
1339  public:
1340   void do_generation(Generation* gen) {
1341     gen->record_spaces_top();
1342   }
1343 };
1344 
1345 void GenCollectedHeap::record_gen_tops_before_GC() {
1346   if (ZapUnusedHeapArea) {
1347     GenGCSaveTopsBeforeGCClosure blk;
1348     generation_iterate(&blk, false);  // not old-to-young.
1349   }
1350 }
1351 #endif  // not PRODUCT
1352 
1353 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1354  public:
1355   void do_generation(Generation* gen) {
1356     gen->ensure_parsability();
1357   }
1358 };
1359 
1360 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1361   CollectedHeap::ensure_parsability(retire_tlabs);
1362   GenEnsureParsabilityClosure ep_cl;
1363   generation_iterate(&ep_cl, false);
1364 }
1365 
1366 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1367                                               oop obj,
1368                                               size_t obj_size) {
1369   guarantee(old_gen == _old_gen, "We only get here with an old generation");
1370   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1371   HeapWord* result = NULL;
1372 
1373   result = old_gen->expand_and_allocate(obj_size, false);
1374 
1375   if (result != NULL) {
1376     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1377   }
1378   return oop(result);
1379 }
1380 
1381 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1382   jlong _time;   // in ms
1383   jlong _now;    // in ms
1384 
1385  public:
1386   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1387 
1388   jlong time() { return _time; }
1389 
1390   void do_generation(Generation* gen) {
1391     _time = MIN2(_time, gen->time_of_last_gc(_now));
1392   }
1393 };
1394 
1395 jlong GenCollectedHeap::millis_since_last_gc() {
1396   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1397   // provided the underlying platform provides such a time source
1398   // (and it is bug free). So we still have to guard against getting
1399   // back a time later than 'now'.
1400   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1401   GenTimeOfLastGCClosure tolgc_cl(now);
1402   // iterate over generations getting the oldest
1403   // time that a generation was collected
1404   generation_iterate(&tolgc_cl, false);
1405 
1406   jlong retVal = now - tolgc_cl.time();
1407   if (retVal < 0) {
1408     log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1409        ". returning zero instead.", retVal);
1410     return 0;
1411   }
1412   return retVal;
1413 }
--- EOF ---