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   MarkSweep::initialize();

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