jdk8-mips64-public/hotspot: src/share/vm/memory/genCollectedHeap.cpp@660978a2a31a (annotated)

src/share/vm/memory/genCollectedHeap.cpp@660978a2a31a (annotated)

src/share/vm/memory/genCollectedHeap.cpp

Thu, 12 Mar 2009 10:37:46 -0700

author: kvn
date: Thu, 12 Mar 2009 10:37:46 -0700
changeset 1077: 660978a2a31a
parent 1050: c6c601a0f2d6
child 1082: bd441136a5ce
permissions: -rw-r--r--

6791178: Specialize for zero as the compressed oop vm heap base
Summary: Use zero based compressed oops if java heap is below 32gb and unscaled compressed oops if java heap is below 4gb.
Reviewed-by: never, twisti, jcoomes, coleenp

 /*
  * Copyright 2000-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 # include "incls/_precompiled.incl"
 # include "incls/_genCollectedHeap.cpp.incl"
 GenCollectedHeap* GenCollectedHeap::_gch;
 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
 // The set of potentially parallel tasks in strong root scanning.
 enum GCH_process_strong_roots_tasks {
   // We probably want to parallelize both of these internally, but for now...
   GCH_PS_younger_gens,
   // Leave this one last.
   GCH_PS_NumElements
 };
 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
   SharedHeap(policy),
   _gen_policy(policy),
   _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
   _full_collections_completed(0)
 {
   if (_gen_process_strong_tasks == NULL ||
       !_gen_process_strong_tasks->valid()) {
     vm_exit_during_initialization("Failed necessary allocation.");
   }
   assert(policy != NULL, "Sanity check");
   _preloading_shared_classes = false;
 }
 jint GenCollectedHeap::initialize() {
   int i;
   _n_gens = gen_policy()->number_of_generations();
   // While there are no constraints in the GC code that HeapWordSize
   // be any particular value, there are multiple other areas in the
   // system which believe this to be true (e.g. oop->object_size in some
   // cases incorrectly returns the size in wordSize units rather than
   // HeapWordSize).
   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
   // The heap must be at least as aligned as generations.
   size_t alignment = Generation::GenGrain;
   _gen_specs = gen_policy()->generations();
   PermanentGenerationSpec *perm_gen_spec =
                                 collector_policy()->permanent_generation();
   // Make sure the sizes are all aligned.
   for (i = 0; i < _n_gens; i++) {
     _gen_specs[i]->align(alignment);
   }
   perm_gen_spec->align(alignment);
   // If we are dumping the heap, then allocate a wasted block of address
   // space in order to push the heap to a lower address.  This extra
   // address range allows for other (or larger) libraries to be loaded
   // without them occupying the space required for the shared spaces.
   if (DumpSharedSpaces) {
     uintx reserved = 0;
     uintx block_size = 64*1024*1024;
     while (reserved < SharedDummyBlockSize) {
       char* dummy = os::reserve_memory(block_size);
       reserved += block_size;
     }
   }
   // Allocate space for the heap.
   char* heap_address;
   size_t total_reserved = 0;
   int n_covered_regions = 0;
   ReservedSpace heap_rs(0);
   heap_address = allocate(alignment, perm_gen_spec, &total_reserved,
                           &n_covered_regions, &heap_rs);
   if (UseSharedSpaces) {
     if (!heap_rs.is_reserved() || heap_address != heap_rs.base()) {
       if (heap_rs.is_reserved()) {
         heap_rs.release();
       }
       FileMapInfo* mapinfo = FileMapInfo::current_info();
       mapinfo->fail_continue("Unable to reserve shared region.");
       allocate(alignment, perm_gen_spec, &total_reserved, &n_covered_regions,
                &heap_rs);
     }
   }
   if (!heap_rs.is_reserved()) {
     vm_shutdown_during_initialization(
       "Could not reserve enough space for object heap");
     return JNI_ENOMEM;
   }
   _reserved = MemRegion((HeapWord*)heap_rs.base(),
                         (HeapWord*)(heap_rs.base() + heap_rs.size()));
   // It is important to do this in a way such that concurrent readers can't
   // temporarily think somethings in the heap.  (Seen this happen in asserts.)
   _reserved.set_word_size(0);
   _reserved.set_start((HeapWord*)heap_rs.base());
   size_t actual_heap_size = heap_rs.size() - perm_gen_spec->misc_data_size()
                                            - perm_gen_spec->misc_code_size();
   _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
   _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
   set_barrier_set(rem_set()->bs());
   _gch = this;
   for (i = 0; i < _n_gens; i++) {
     ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(),
                                               UseSharedSpaces, UseSharedSpaces);
     _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
     heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
   }
   _perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set());
   clear_incremental_collection_will_fail();
   clear_last_incremental_collection_failed();
 #ifndef SERIALGC
   // If we are running CMS, create the collector responsible
   // for collecting the CMS generations.
   if (collector_policy()->is_concurrent_mark_sweep_policy()) {
     bool success = create_cms_collector();
     if (!success) return JNI_ENOMEM;
   }
 #endif // SERIALGC
   return JNI_OK;
 }
 char* GenCollectedHeap::allocate(size_t alignment,
                                  PermanentGenerationSpec* perm_gen_spec,
                                  size_t* _total_reserved,
                                  int* _n_covered_regions,
                                  ReservedSpace* heap_rs){
   const char overflow_msg[] = "The size of the object heap + VM data exceeds "
     "the maximum representable size";
   // Now figure out the total size.
   size_t total_reserved = 0;
   int n_covered_regions = 0;
   const size_t pageSize = UseLargePages ?
       os::large_page_size() : os::vm_page_size();
   for (int i = 0; i < _n_gens; i++) {
     total_reserved += _gen_specs[i]->max_size();
     if (total_reserved < _gen_specs[i]->max_size()) {
       vm_exit_during_initialization(overflow_msg);
     }
     n_covered_regions += _gen_specs[i]->n_covered_regions();
   }
   assert(total_reserved % pageSize == 0, "Gen size");
   total_reserved += perm_gen_spec->max_size();
   assert(total_reserved % pageSize == 0, "Perm Gen size");
   if (total_reserved < perm_gen_spec->max_size()) {
     vm_exit_during_initialization(overflow_msg);
   }
   n_covered_regions += perm_gen_spec->n_covered_regions();
   // Add the size of the data area which shares the same reserved area
   // as the heap, but which is not actually part of the heap.
   size_t s = perm_gen_spec->misc_data_size() + perm_gen_spec->misc_code_size();
   total_reserved += s;
   if (total_reserved < s) {
     vm_exit_during_initialization(overflow_msg);
   }
   if (UseLargePages) {
     assert(total_reserved != 0, "total_reserved cannot be 0");
     total_reserved = round_to(total_reserved, os::large_page_size());
     if (total_reserved < os::large_page_size()) {
       vm_exit_during_initialization(overflow_msg);
     }
   }
   // Calculate the address at which the heap must reside in order for
   // the shared data to be at the required address.
   char* heap_address;
   if (UseSharedSpaces) {
     // Calculate the address of the first word beyond the heap.
     FileMapInfo* mapinfo = FileMapInfo::current_info();
     int lr = CompactingPermGenGen::n_regions - 1;
     size_t capacity = align_size_up(mapinfo->space_capacity(lr), alignment);
     heap_address = mapinfo->region_base(lr) + capacity;
     // Calculate the address of the first word of the heap.
     heap_address -= total_reserved;
   } else {
     heap_address = NULL;  // any address will do.
     if (UseCompressedOops) {
       heap_address = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
       *_total_reserved = total_reserved;
       *_n_covered_regions = n_covered_regions;
       *heap_rs = ReservedHeapSpace(total_reserved, alignment,
                                    UseLargePages, heap_address);
       if (heap_address != NULL && !heap_rs->is_reserved()) {
         // Failed to reserve at specified address - the requested memory
         // region is taken already, for example, by 'java' launcher.
         // Try again to reserver heap higher.
         heap_address = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
         *heap_rs = ReservedHeapSpace(total_reserved, alignment,
                                      UseLargePages, heap_address);
         if (heap_address != NULL && !heap_rs->is_reserved()) {
           // Failed to reserve at specified address again - give up.
           heap_address = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
           assert(heap_address == NULL, "");
           *heap_rs = ReservedHeapSpace(total_reserved, alignment,
                                        UseLargePages, heap_address);
         }
       }
       return heap_address;
     }
   }
   *_total_reserved = total_reserved;
   *_n_covered_regions = n_covered_regions;
   *heap_rs = ReservedHeapSpace(total_reserved, alignment,
                                UseLargePages, heap_address);
   return heap_address;
 }
 void GenCollectedHeap::post_initialize() {
   SharedHeap::post_initialize();
   TwoGenerationCollectorPolicy *policy =
     (TwoGenerationCollectorPolicy *)collector_policy();
   guarantee(policy->is_two_generation_policy(), "Illegal policy type");
   DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
   assert(def_new_gen->kind() == Generation::DefNew ||
          def_new_gen->kind() == Generation::ParNew ||
          def_new_gen->kind() == Generation::ASParNew,
          "Wrong generation kind");
   Generation* old_gen = get_gen(1);
   assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
          old_gen->kind() == Generation::ASConcurrentMarkSweep ||
          old_gen->kind() == Generation::MarkSweepCompact,
     "Wrong generation kind");
   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
                                  old_gen->capacity(),
                                  def_new_gen->from()->capacity());
   policy->initialize_gc_policy_counters();
 }
 void GenCollectedHeap::ref_processing_init() {
   SharedHeap::ref_processing_init();
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->ref_processor_init();
   }
 }
 size_t GenCollectedHeap::capacity() const {
   size_t res = 0;
   for (int i = 0; i < _n_gens; i++) {
     res += _gens[i]->capacity();
   }
   return res;
 }
 size_t GenCollectedHeap::used() const {
   size_t res = 0;
   for (int i = 0; i < _n_gens; i++) {
     res += _gens[i]->used();
   }
   return res;
 }
 // Save the "used_region" for generations level and lower,
 // and, if perm is true, for perm gen.
 void GenCollectedHeap::save_used_regions(int level, bool perm) {
   assert(level < _n_gens, "Illegal level parameter");
   for (int i = level; i >= 0; i--) {
     _gens[i]->save_used_region();
   }
   if (perm) {
     perm_gen()->save_used_region();
   }
 }
 size_t GenCollectedHeap::max_capacity() const {
   size_t res = 0;
   for (int i = 0; i < _n_gens; i++) {
     res += _gens[i]->max_capacity();
   }
   return res;
 }
 // Update the _full_collections_completed counter
 // at the end of a stop-world full GC.
 unsigned int GenCollectedHeap::update_full_collections_completed() {
   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
   assert(_full_collections_completed <= _total_full_collections,
          "Can't complete more collections than were started");
   _full_collections_completed = _total_full_collections;
   ml.notify_all();
   return _full_collections_completed;
 }
 // Update the _full_collections_completed counter, as appropriate,
 // at the end of a concurrent GC cycle. Note the conditional update
 // below to allow this method to be called by a concurrent collector
 // without synchronizing in any manner with the VM thread (which
 // may already have initiated a STW full collection "concurrently").
 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
   assert((_full_collections_completed <= _total_full_collections) &&
          (count <= _total_full_collections),
          "Can't complete more collections than were started");
   if (count > _full_collections_completed) {
     _full_collections_completed = count;
     ml.notify_all();
   }
   return _full_collections_completed;
 }
 #ifndef PRODUCT
 // Override of memory state checking method in CollectedHeap:
 // Some collectors (CMS for example) can't have badHeapWordVal written
 // in the first two words of an object. (For instance , in the case of
 // CMS these words hold state used to synchronize between certain
 // (concurrent) GC steps and direct allocating mutators.)
 // The skip_header_HeapWords() method below, allows us to skip
 // over the requisite number of HeapWord's. Note that (for
 // generational collectors) this means that those many words are
 // skipped in each object, irrespective of the generation in which
 // that object lives. The resultant loss of precision seems to be
 // harmless and the pain of avoiding that imprecision appears somewhat
 // higher than we are prepared to pay for such rudimentary debugging
 // support.
 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
                                                          size_t size) {
   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
     // We are asked to check a size in HeapWords,
     // but the memory is mangled in juint words.
     juint* start = (juint*) (addr + skip_header_HeapWords());
     juint* end   = (juint*) (addr + size);
     for (juint* slot = start; slot < end; slot += 1) {
       assert(*slot == badHeapWordVal,
              "Found non badHeapWordValue in pre-allocation check");
     }
   }
 }
 #endif
 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
                                                bool is_tlab,
                                                bool first_only) {
   HeapWord* res;
   for (int i = 0; i < _n_gens; i++) {
     if (_gens[i]->should_allocate(size, is_tlab)) {
       res = _gens[i]->allocate(size, is_tlab);
       if (res != NULL) return res;
       else if (first_only) break;
     }
   }
   // Otherwise...
   return NULL;
 }
 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
                                          bool is_large_noref,
                                          bool is_tlab,
                                          bool* gc_overhead_limit_was_exceeded) {
   return collector_policy()->mem_allocate_work(size,
                                                is_tlab,
                                                gc_overhead_limit_was_exceeded);
 }
 bool GenCollectedHeap::must_clear_all_soft_refs() {
   return _gc_cause == GCCause::_last_ditch_collection;
 }
 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
   return (cause == GCCause::_java_lang_system_gc ||
           cause == GCCause::_gc_locker) &&
          UseConcMarkSweepGC && ExplicitGCInvokesConcurrent;
 }
 void GenCollectedHeap::do_collection(bool  full,
                                      bool   clear_all_soft_refs,
                                      size_t size,
                                      bool   is_tlab,
                                      int    max_level) {
   bool prepared_for_verification = false;
   ResourceMark rm;
   DEBUG_ONLY(Thread* my_thread = Thread::current();)
   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
   assert(my_thread->is_VM_thread() ||
          my_thread->is_ConcurrentGC_thread(),
          "incorrect thread type capability");
   assert(Heap_lock->is_locked(), "the requesting thread should have the Heap_lock");
   guarantee(!is_gc_active(), "collection is not reentrant");
   assert(max_level < n_gens(), "sanity check");
   if (GC_locker::check_active_before_gc()) {
     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
   }
   const size_t perm_prev_used = perm_gen()->used();
   if (PrintHeapAtGC) {
     Universe::print_heap_before_gc();
     if (Verbose) {
       gclog_or_tty->print_cr("GC Cause: %s", GCCause::to_string(gc_cause()));
     }
   }
   {
     FlagSetting fl(_is_gc_active, true);
     bool complete = full && (max_level == (n_gens()-1));
     const char* gc_cause_str = "GC ";
     if (complete) {
       GCCause::Cause cause = gc_cause();
       if (cause == GCCause::_java_lang_system_gc) {
         gc_cause_str = "Full GC (System) ";
       } else {
         gc_cause_str = "Full GC ";
       }
     }
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
     TraceTime t(gc_cause_str, PrintGCDetails, false, gclog_or_tty);
     gc_prologue(complete);
     increment_total_collections(complete);
     size_t gch_prev_used = used();
     int starting_level = 0;
     if (full) {
       // Search for the oldest generation which will collect all younger
       // generations, and start collection loop there.
       for (int i = max_level; i >= 0; i--) {
         if (_gens[i]->full_collects_younger_generations()) {
           starting_level = i;
           break;
         }
       }
     }
     bool must_restore_marks_for_biased_locking = false;
     int max_level_collected = starting_level;
     for (int i = starting_level; i <= max_level; i++) {
       if (_gens[i]->should_collect(full, size, is_tlab)) {
         if (i == n_gens() - 1) {  // a major collection is to happen
           pre_full_gc_dump();    // do any pre full gc dumps
         }
         // Timer for individual generations. Last argument is false: no CR
         TraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, gclog_or_tty);
         TraceCollectorStats tcs(_gens[i]->counters());
         TraceMemoryManagerStats tmms(_gens[i]->kind());
         size_t prev_used = _gens[i]->used();
         _gens[i]->stat_record()->invocations++;
         _gens[i]->stat_record()->accumulated_time.start();
         // Must be done anew before each collection because
         // a previous collection will do mangling and will
         // change top of some spaces.
         record_gen_tops_before_GC();
         if (PrintGC && Verbose) {
           gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
                      i,
                      _gens[i]->stat_record()->invocations,
                      size*HeapWordSize);
         }
         if (VerifyBeforeGC && i >= VerifyGCLevel &&
             total_collections() >= VerifyGCStartAt) {
           HandleMark hm;  // Discard invalid handles created during verification
           if (!prepared_for_verification) {
             prepare_for_verify();
             prepared_for_verification = true;
           }
           gclog_or_tty->print(" VerifyBeforeGC:");
           Universe::verify(true);
         }
         COMPILER2_PRESENT(DerivedPointerTable::clear());
         if (!must_restore_marks_for_biased_locking &&
             _gens[i]->performs_in_place_marking()) {
           // We perform this mark word preservation work lazily
           // because it's only at this point that we know whether we
           // absolutely have to do it; we want to avoid doing it for
           // scavenge-only collections where it's unnecessary
           must_restore_marks_for_biased_locking = true;
           BiasedLocking::preserve_marks();
         }
         // Do collection work
         {
           // Note on ref discovery: For what appear to be historical reasons,
           // GCH enables and disabled (by enqueing) refs discovery.
           // In the future this should be moved into the generation's
           // collect method so that ref discovery and enqueueing concerns
           // are local to a generation. The collect method could return
           // an appropriate indication in the case that notification on
           // the ref lock was needed. This will make the treatment of
           // weak refs more uniform (and indeed remove such concerns
           // from GCH). XXX
           HandleMark hm;  // Discard invalid handles created during gc
           save_marks();   // save marks for all gens
           // We want to discover references, but not process them yet.
           // This mode is disabled in process_discovered_references if the
           // generation does some collection work, or in
           // enqueue_discovered_references if the generation returns
           // without doing any work.
           ReferenceProcessor* rp = _gens[i]->ref_processor();
           // If the discovery of ("weak") refs in this generation is
           // atomic wrt other collectors in this configuration, we
           // are guaranteed to have empty discovered ref lists.
           if (rp->discovery_is_atomic()) {
             rp->verify_no_references_recorded();
             rp->enable_discovery();
             rp->setup_policy(clear_all_soft_refs);
           } else {
             // collect() below will enable discovery as appropriate
           }
           _gens[i]->collect(full, clear_all_soft_refs, size, is_tlab);
           if (!rp->enqueuing_is_done()) {
             rp->enqueue_discovered_references();
           } else {
             rp->set_enqueuing_is_done(false);
           }
           rp->verify_no_references_recorded();
         }
         max_level_collected = i;
         // Determine if allocation request was met.
         if (size > 0) {
           if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
             if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
               size = 0;
             }
           }
         }
         COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
         _gens[i]->stat_record()->accumulated_time.stop();
         update_gc_stats(i, full);
         if (VerifyAfterGC && i >= VerifyGCLevel &&
             total_collections() >= VerifyGCStartAt) {
           HandleMark hm;  // Discard invalid handles created during verification
           gclog_or_tty->print(" VerifyAfterGC:");
           Universe::verify(false);
         }
         if (PrintGCDetails) {
           gclog_or_tty->print(":");
           _gens[i]->print_heap_change(prev_used);
         }
       }
     }
     // Update "complete" boolean wrt what actually transpired --
     // for instance, a promotion failure could have led to
     // a whole heap collection.
     complete = complete || (max_level_collected == n_gens() - 1);
     if (complete) { // We did a "major" collection
       post_full_gc_dump();   // do any post full gc dumps
     }
     if (PrintGCDetails) {
       print_heap_change(gch_prev_used);
       // Print perm gen info for full GC with PrintGCDetails flag.
       if (complete) {
         print_perm_heap_change(perm_prev_used);
       }
     }
     for (int j = max_level_collected; j >= 0; j -= 1) {
       // Adjust generation sizes.
       _gens[j]->compute_new_size();
     }
     if (complete) {
       // Ask the permanent generation to adjust size for full collections
       perm()->compute_new_size();
       update_full_collections_completed();
     }
     // Track memory usage and detect low memory after GC finishes
     MemoryService::track_memory_usage();
     gc_epilogue(complete);
     if (must_restore_marks_for_biased_locking) {
       BiasedLocking::restore_marks();
     }
   }
   AdaptiveSizePolicy* sp = gen_policy()->size_policy();
   AdaptiveSizePolicyOutput(sp, total_collections());
   if (PrintHeapAtGC) {
     Universe::print_heap_after_gc();
   }
 #ifdef TRACESPINNING
   ParallelTaskTerminator::print_termination_counts();
 #endif
   if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
     tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
     vm_exit(-1);
   }
 }
 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 }
 void GenCollectedHeap::set_par_threads(int t) {
   SharedHeap::set_par_threads(t);
   _gen_process_strong_tasks->set_par_threads(t);
 }
 class AssertIsPermClosure: public OopClosure {
 public:
   void do_oop(oop* p) {
     assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
   }
   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 };
 static AssertIsPermClosure assert_is_perm_closure;
 void GenCollectedHeap::
 gen_process_strong_roots(int level,
                          bool younger_gens_as_roots,
                          bool collecting_perm_gen,
                          SharedHeap::ScanningOption so,
                          OopsInGenClosure* older_gens,
                          OopsInGenClosure* not_older_gens) {
   // General strong roots.
   SharedHeap::process_strong_roots(collecting_perm_gen, so,
                                    not_older_gens, older_gens);
   if (younger_gens_as_roots) {
     if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
       for (int i = 0; i < level; i++) {
         not_older_gens->set_generation(_gens[i]);
         _gens[i]->oop_iterate(not_older_gens);
       }
       not_older_gens->reset_generation();
     }
   }
   // When collection is parallel, all threads get to cooperate to do
   // older-gen scanning.
   for (int i = level+1; i < _n_gens; i++) {
     older_gens->set_generation(_gens[i]);
     rem_set()->younger_refs_iterate(_gens[i], older_gens);
     older_gens->reset_generation();
   }
   _gen_process_strong_tasks->all_tasks_completed();
 }
 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
                                               OopClosure* non_root_closure) {
   SharedHeap::process_weak_roots(root_closure, non_root_closure);
   // "Local" "weak" refs
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->ref_processor()->weak_oops_do(root_closure);
   }
 }
 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 void GenCollectedHeap::                                                 \
 oop_since_save_marks_iterate(int level,                                 \
                              OopClosureType* cur,                       \
                              OopClosureType* older) {                   \
   _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur);           \
   for (int i = level+1; i < n_gens(); i++) {                            \
     _gens[i]->oop_since_save_marks_iterate##nv_suffix(older);           \
   }                                                                     \
   perm_gen()->oop_since_save_marks_iterate##nv_suffix(older);           \
 }
 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
   for (int i = level; i < _n_gens; i++) {
     if (!_gens[i]->no_allocs_since_save_marks()) return false;
   }
   return perm_gen()->no_allocs_since_save_marks();
 }
 bool GenCollectedHeap::supports_inline_contig_alloc() const {
   return _gens[0]->supports_inline_contig_alloc();
 }
 HeapWord** GenCollectedHeap::top_addr() const {
   return _gens[0]->top_addr();
 }
 HeapWord** GenCollectedHeap::end_addr() const {
   return _gens[0]->end_addr();
 }
 size_t GenCollectedHeap::unsafe_max_alloc() {
   return _gens[0]->unsafe_max_alloc_nogc();
 }
 // public collection interfaces
 void GenCollectedHeap::collect(GCCause::Cause cause) {
   if (should_do_concurrent_full_gc(cause)) {
 #ifndef SERIALGC
     // mostly concurrent full collection
     collect_mostly_concurrent(cause);
 #else  // SERIALGC
     ShouldNotReachHere();
 #endif // SERIALGC
   } else {
 #ifdef ASSERT
     if (cause == GCCause::_scavenge_alot) {
       // minor collection only
       collect(cause, 0);
     } else {
       // Stop-the-world full collection
       collect(cause, n_gens() - 1);
     }
 #else
     // Stop-the-world full collection
     collect(cause, n_gens() - 1);
 #endif
   }
 }
 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
   // The caller doesn't have the Heap_lock
   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
   MutexLocker ml(Heap_lock);
   collect_locked(cause, max_level);
 }
 // This interface assumes that it's being called by the
 // vm thread. It collects the heap assuming that the
 // heap lock is already held and that we are executing in
 // the context of the vm thread.
 void GenCollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
   assert(Thread::current()->is_VM_thread(), "Precondition#1");
   assert(Heap_lock->is_locked(), "Precondition#2");
   GCCauseSetter gcs(this, cause);
   switch (cause) {
     case GCCause::_heap_inspection:
     case GCCause::_heap_dump: {
       HandleMark hm;
       do_full_collection(false,         // don't clear all soft refs
                          n_gens() - 1);
       break;
     }
     default: // XXX FIX ME
       ShouldNotReachHere(); // Unexpected use of this function
   }
 }
 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
   // The caller has the Heap_lock
   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
   collect_locked(cause, n_gens() - 1);
 }
 // this is the private collection interface
 // The Heap_lock is expected to be held on entry.
 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
   if (_preloading_shared_classes) {
     warning("\nThe permanent generation is not large enough to preload "
             "requested classes.\nUse -XX:PermSize= to increase the initial "
             "size of the permanent generation.\n");
     vm_exit(2);
   }
   // Read the GC count while holding the Heap_lock
   unsigned int gc_count_before      = total_collections();
   unsigned int full_gc_count_before = total_full_collections();
   {
     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
                          cause, max_level);
     VMThread::execute(&op);
   }
 }
 #ifndef SERIALGC
 bool GenCollectedHeap::create_cms_collector() {
   assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
          (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)) &&
          _perm_gen->as_gen()->kind() == Generation::ConcurrentMarkSweep,
          "Unexpected generation kinds");
   // Skip two header words in the block content verification
   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
   CMSCollector* collector = new CMSCollector(
     (ConcurrentMarkSweepGeneration*)_gens[1],
     (ConcurrentMarkSweepGeneration*)_perm_gen->as_gen(),
     _rem_set->as_CardTableRS(),
     (ConcurrentMarkSweepPolicy*) collector_policy());
   if (collector == NULL || !collector->completed_initialization()) {
     if (collector) {
       delete collector;  // Be nice in embedded situation
     }
     vm_shutdown_during_initialization("Could not create CMS collector");
     return false;
   }
   return true;  // success
 }
 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
   MutexLocker ml(Heap_lock);
   // Read the GC counts while holding the Heap_lock
   unsigned int full_gc_count_before = total_full_collections();
   unsigned int gc_count_before      = total_collections();
   {
     MutexUnlocker mu(Heap_lock);
     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
     VMThread::execute(&op);
   }
 }
 #endif // SERIALGC
 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
                                           int max_level) {
   int local_max_level;
   if (!incremental_collection_will_fail() &&
       gc_cause() == GCCause::_gc_locker) {
     local_max_level = 0;
   } else {
     local_max_level = max_level;
   }
   do_collection(true                 /* full */,
                 clear_all_soft_refs  /* clear_all_soft_refs */,
 /* size */,
                 false                /* is_tlab */,
                 local_max_level      /* max_level */);
   // Hack XXX FIX ME !!!
   // A scavenge may not have been attempted, or may have
   // been attempted and failed, because the old gen was too full
   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
       incremental_collection_will_fail()) {
     if (PrintGCDetails) {
       gclog_or_tty->print_cr("GC locker: Trying a full collection "
                              "because scavenge failed");
     }
     // This time allow the old gen to be collected as well
     do_collection(true                 /* full */,
                   clear_all_soft_refs  /* clear_all_soft_refs */,
 /* size */,
                   false                /* is_tlab */,
                   n_gens() - 1         /* max_level */);
   }
 }
 // Returns "TRUE" iff "p" points into the allocated area of the heap.
 bool GenCollectedHeap::is_in(const void* p) const {
   #ifndef ASSERT
   guarantee(VerifyBeforeGC   ||
             VerifyDuringGC   ||
             VerifyBeforeExit ||
             VerifyAfterGC, "too expensive");
   #endif
   // This might be sped up with a cache of the last generation that
   // answered yes.
   for (int i = 0; i < _n_gens; i++) {
     if (_gens[i]->is_in(p)) return true;
   }
   if (_perm_gen->as_gen()->is_in(p)) return true;
   // Otherwise...
   return false;
 }
 // Returns "TRUE" iff "p" points into the allocated area of the heap.
 bool GenCollectedHeap::is_in_youngest(void* p) {
   return _gens[0]->is_in(p);
 }
 void GenCollectedHeap::oop_iterate(OopClosure* cl) {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->oop_iterate(cl);
   }
 }
 void GenCollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->oop_iterate(mr, cl);
   }
 }
 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->object_iterate(cl);
   }
   perm_gen()->object_iterate(cl);
 }
 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->safe_object_iterate(cl);
   }
   perm_gen()->safe_object_iterate(cl);
 }
 void GenCollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->object_iterate_since_last_GC(cl);
   }
 }
 Space* GenCollectedHeap::space_containing(const void* addr) const {
   for (int i = 0; i < _n_gens; i++) {
     Space* res = _gens[i]->space_containing(addr);
     if (res != NULL) return res;
   }
   Space* res = perm_gen()->space_containing(addr);
   if (res != NULL) return res;
   // Otherwise...
   assert(false, "Could not find containing space");
   return NULL;
 }
 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
   assert(is_in_reserved(addr), "block_start of address outside of heap");
   for (int i = 0; i < _n_gens; i++) {
     if (_gens[i]->is_in_reserved(addr)) {
       assert(_gens[i]->is_in(addr),
              "addr should be in allocated part of generation");
       return _gens[i]->block_start(addr);
     }
   }
   if (perm_gen()->is_in_reserved(addr)) {
     assert(perm_gen()->is_in(addr),
            "addr should be in allocated part of perm gen");
     return perm_gen()->block_start(addr);
   }
   assert(false, "Some generation should contain the address");
   return NULL;
 }
 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
   assert(is_in_reserved(addr), "block_size of address outside of heap");
   for (int i = 0; i < _n_gens; i++) {
     if (_gens[i]->is_in_reserved(addr)) {
       assert(_gens[i]->is_in(addr),
              "addr should be in allocated part of generation");
       return _gens[i]->block_size(addr);
     }
   }
   if (perm_gen()->is_in_reserved(addr)) {
     assert(perm_gen()->is_in(addr),
            "addr should be in allocated part of perm gen");
     return perm_gen()->block_size(addr);
   }
   assert(false, "Some generation should contain the address");
   return 0;
 }
 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
   assert(block_start(addr) == addr, "addr must be a block start");
   for (int i = 0; i < _n_gens; i++) {
     if (_gens[i]->is_in_reserved(addr)) {
       return _gens[i]->block_is_obj(addr);
     }
   }
   if (perm_gen()->is_in_reserved(addr)) {
     return perm_gen()->block_is_obj(addr);
   }
   assert(false, "Some generation should contain the address");
   return false;
 }
 bool GenCollectedHeap::supports_tlab_allocation() const {
   for (int i = 0; i < _n_gens; i += 1) {
     if (_gens[i]->supports_tlab_allocation()) {
       return true;
     }
   }
   return false;
 }
 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
   size_t result = 0;
   for (int i = 0; i < _n_gens; i += 1) {
     if (_gens[i]->supports_tlab_allocation()) {
       result += _gens[i]->tlab_capacity();
     }
   }
   return result;
 }
 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
   size_t result = 0;
   for (int i = 0; i < _n_gens; i += 1) {
     if (_gens[i]->supports_tlab_allocation()) {
       result += _gens[i]->unsafe_max_tlab_alloc();
     }
   }
   return result;
 }
 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
   bool gc_overhead_limit_was_exceeded;
   HeapWord* result = mem_allocate(size   /* size */,
                                   false  /* is_large_noref */,
                                   true   /* is_tlab */,
                                   &gc_overhead_limit_was_exceeded);
   return result;
 }
 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
 // from the list headed by "*prev_ptr".
 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
   bool first = true;
   size_t min_size = 0;   // "first" makes this conceptually infinite.
   ScratchBlock **smallest_ptr, *smallest;
   ScratchBlock  *cur = *prev_ptr;
   while (cur) {
     assert(*prev_ptr == cur, "just checking");
     if (first || cur->num_words < min_size) {
       smallest_ptr = prev_ptr;
       smallest     = cur;
       min_size     = smallest->num_words;
       first        = false;
     }
     prev_ptr = &cur->next;
     cur     =  cur->next;
   }
   smallest      = *smallest_ptr;
   *smallest_ptr = smallest->next;
   return smallest;
 }
 // Sort the scratch block list headed by res into decreasing size order,
 // and set "res" to the result.
 static void sort_scratch_list(ScratchBlock*& list) {
   ScratchBlock* sorted = NULL;
   ScratchBlock* unsorted = list;
   while (unsorted) {
     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
     smallest->next  = sorted;
     sorted          = smallest;
   }
   list = sorted;
 }
 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
                                                size_t max_alloc_words) {
   ScratchBlock* res = NULL;
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
   }
   sort_scratch_list(res);
   return res;
 }
 void GenCollectedHeap::release_scratch() {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->reset_scratch();
   }
 }
 size_t GenCollectedHeap::large_typearray_limit() {
   return gen_policy()->large_typearray_limit();
 }
 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
   void do_generation(Generation* gen) {
     gen->prepare_for_verify();
   }
 };
 void GenCollectedHeap::prepare_for_verify() {
   ensure_parsability(false);        // no need to retire TLABs
   GenPrepareForVerifyClosure blk;
   generation_iterate(&blk, false);
   perm_gen()->prepare_for_verify();
 }
 void GenCollectedHeap::generation_iterate(GenClosure* cl,
                                           bool old_to_young) {
   if (old_to_young) {
     for (int i = _n_gens-1; i >= 0; i--) {
       cl->do_generation(_gens[i]);
     }
   } else {
     for (int i = 0; i < _n_gens; i++) {
       cl->do_generation(_gens[i]);
     }
   }
 }
 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->space_iterate(cl, true);
   }
   perm_gen()->space_iterate(cl, true);
 }
 bool GenCollectedHeap::is_maximal_no_gc() const {
   for (int i = 0; i < _n_gens; i++) {  // skip perm gen
     if (!_gens[i]->is_maximal_no_gc()) {
       return false;
     }
   }
   return true;
 }
 void GenCollectedHeap::save_marks() {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->save_marks();
   }
   perm_gen()->save_marks();
 }
 void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) {
   for (int i = 0; i <= collectedGen; i++) {
     _gens[i]->compute_new_size();
   }
 }
 GenCollectedHeap* GenCollectedHeap::heap() {
   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
   return _gch;
 }
 void GenCollectedHeap::prepare_for_compaction() {
   Generation* scanning_gen = _gens[_n_gens-1];
   // Start by compacting into same gen.
   CompactPoint cp(scanning_gen, NULL, NULL);
   while (scanning_gen != NULL) {
     scanning_gen->prepare_for_compaction(&cp);
     scanning_gen = prev_gen(scanning_gen);
   }
 }
 GCStats* GenCollectedHeap::gc_stats(int level) const {
   return _gens[level]->gc_stats();
 }
 void GenCollectedHeap::verify(bool allow_dirty, bool silent) {
   if (!silent) {
     gclog_or_tty->print("permgen ");
   }
   perm_gen()->verify(allow_dirty);
   for (int i = _n_gens-1; i >= 0; i--) {
     Generation* g = _gens[i];
     if (!silent) {
       gclog_or_tty->print(g->name());
       gclog_or_tty->print(" ");
     }
     g->verify(allow_dirty);
   }
   if (!silent) {
     gclog_or_tty->print("remset ");
   }
   rem_set()->verify();
   if (!silent) {
      gclog_or_tty->print("ref_proc ");
   }
   ReferenceProcessor::verify();
 }
 void GenCollectedHeap::print() const { print_on(tty); }
 void GenCollectedHeap::print_on(outputStream* st) const {
   for (int i = 0; i < _n_gens; i++) {
     _gens[i]->print_on(st);
   }
   perm_gen()->print_on(st);
 }
 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
   if (workers() != NULL) {
     workers()->threads_do(tc);
   }
 #ifndef SERIALGC
   if (UseConcMarkSweepGC) {
     ConcurrentMarkSweepThread::threads_do(tc);
   }
 #endif // SERIALGC
 }
 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
 #ifndef SERIALGC
   if (UseParNewGC) {
     workers()->print_worker_threads_on(st);
   }
   if (UseConcMarkSweepGC) {
     ConcurrentMarkSweepThread::print_all_on(st);
   }
 #endif // SERIALGC
 }
 void GenCollectedHeap::print_tracing_info() const {
   if (TraceGen0Time) {
     get_gen(0)->print_summary_info();
   }
   if (TraceGen1Time) {
     get_gen(1)->print_summary_info();
   }
 }
 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
   if (PrintGCDetails && Verbose) {
     gclog_or_tty->print(" "  SIZE_FORMAT
                         "->" SIZE_FORMAT
                         "("  SIZE_FORMAT ")",
                         prev_used, used(), capacity());
   } else {
     gclog_or_tty->print(" "  SIZE_FORMAT "K"
                         "->" SIZE_FORMAT "K"
                         "("  SIZE_FORMAT "K)",
                         prev_used / K, used() / K, capacity() / K);
   }
 }
 //New method to print perm gen info with PrintGCDetails flag
 void GenCollectedHeap::print_perm_heap_change(size_t perm_prev_used) const {
   gclog_or_tty->print(", [%s :", perm_gen()->short_name());
   perm_gen()->print_heap_change(perm_prev_used);
   gclog_or_tty->print("]");
 }
 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
  private:
   bool _full;
  public:
   void do_generation(Generation* gen) {
     gen->gc_prologue(_full);
   }
   GenGCPrologueClosure(bool full) : _full(full) {};
 };
 void GenCollectedHeap::gc_prologue(bool full) {
   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
   always_do_update_barrier = false;
   // Fill TLAB's and such
   CollectedHeap::accumulate_statistics_all_tlabs();
   ensure_parsability(true);   // retire TLABs
   // Call allocation profiler
   AllocationProfiler::iterate_since_last_gc();
   // Walk generations
   GenGCPrologueClosure blk(full);
   generation_iterate(&blk, false);  // not old-to-young.
   perm_gen()->gc_prologue(full);
 };
 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
  private:
   bool _full;
  public:
   void do_generation(Generation* gen) {
     gen->gc_epilogue(_full);
   }
   GenGCEpilogueClosure(bool full) : _full(full) {};
 };
 void GenCollectedHeap::gc_epilogue(bool full) {
   // Remember if a partial collection of the heap failed, and
   // we did a complete collection.
   if (full && incremental_collection_will_fail()) {
     set_last_incremental_collection_failed();
   } else {
     clear_last_incremental_collection_failed();
   }
   // Clear the flag, if set; the generation gc_epilogues will set the
   // flag again if the condition persists despite the collection.
   clear_incremental_collection_will_fail();
 #ifdef COMPILER2
   assert(DerivedPointerTable::is_empty(), "derived pointer present");
   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
 #endif /* COMPILER2 */
   resize_all_tlabs();
   GenGCEpilogueClosure blk(full);
   generation_iterate(&blk, false);  // not old-to-young.
   perm_gen()->gc_epilogue(full);
   always_do_update_barrier = UseConcMarkSweepGC;
 };
 #ifndef PRODUCT
 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
  private:
  public:
   void do_generation(Generation* gen) {
     gen->record_spaces_top();
   }
 };
 void GenCollectedHeap::record_gen_tops_before_GC() {
   if (ZapUnusedHeapArea) {
     GenGCSaveTopsBeforeGCClosure blk;
     generation_iterate(&blk, false);  // not old-to-young.
     perm_gen()->record_spaces_top();
   }
 }
 #endif  // not PRODUCT
 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
  public:
   void do_generation(Generation* gen) {
     gen->ensure_parsability();
   }
 };
 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
   CollectedHeap::ensure_parsability(retire_tlabs);
   GenEnsureParsabilityClosure ep_cl;
   generation_iterate(&ep_cl, false);
   perm_gen()->ensure_parsability();
 }
 oop GenCollectedHeap::handle_failed_promotion(Generation* gen,
                                               oop obj,
                                               size_t obj_size) {
   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
   HeapWord* result = NULL;
   // First give each higher generation a chance to allocate the promoted object.
   Generation* allocator = next_gen(gen);
   if (allocator != NULL) {
     do {
       result = allocator->allocate(obj_size, false);
     } while (result == NULL && (allocator = next_gen(allocator)) != NULL);
   }
   if (result == NULL) {
     // Then give gen and higher generations a chance to expand and allocate the
     // object.
     do {
       result = gen->expand_and_allocate(obj_size, false);
     } while (result == NULL && (gen = next_gen(gen)) != NULL);
   }
   if (result != NULL) {
     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
   }
   return oop(result);
 }
 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
   jlong _time;   // in ms
   jlong _now;    // in ms
  public:
   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
   jlong time() { return _time; }
   void do_generation(Generation* gen) {
     _time = MIN2(_time, gen->time_of_last_gc(_now));
   }
 };
 jlong GenCollectedHeap::millis_since_last_gc() {
   jlong now = os::javaTimeMillis();
   GenTimeOfLastGCClosure tolgc_cl(now);
   // iterate over generations getting the oldest
   // time that a generation was collected
   generation_iterate(&tolgc_cl, false);
   tolgc_cl.do_generation(perm_gen());
   // XXX Despite the assert above, since javaTimeMillis()
   // doesnot guarantee monotonically increasing return
   // values (note, i didn't say "strictly monotonic"),
   // we need to guard against getting back a time
   // later than now. This should be fixed by basing
   // on someting like gethrtime() which guarantees
   // monotonicity. Note that cond_wait() is susceptible
   // to a similar problem, because its interface is
   // based on absolute time in the form of the
   // system time's notion of UCT. See also 4506635
   // for yet another problem of similar nature. XXX
   jlong retVal = now - tolgc_cl.time();
   if (retVal < 0) {
     NOT_PRODUCT(warning("time warp: %d", retVal);)
     return 0;
   }
   return retVal;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/genCollectedHeap.cpp@660978a2a31a (annotated)

src/share/vm/memory/genCollectedHeap.cpp