jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

Mon, 09 Aug 2010 05:41:05 -0700

author: jcoomes
date: Mon, 09 Aug 2010 05:41:05 -0700
changeset 2064: 5f429ee79634
parent 2062: 0ce1569c90e5
child 2072: 688c3755d7af
permissions: -rw-r--r--

6966222: G1: simplify TaskQueue overflow handling
Reviewed-by: tonyp, ysr

 /*
  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "incls/_precompiled.incl"
 #include "incls/_g1CollectedHeap.cpp.incl"
 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
 // turn it on so that the contents of the young list (scan-only /
 // to-be-collected) are printed at "strategic" points before / during
 // / after the collection --- this is useful for debugging
 #define YOUNG_LIST_VERBOSE 0
 // CURRENT STATUS
 // This file is under construction.  Search for "FIXME".
 // INVARIANTS/NOTES
 //
 // All allocation activity covered by the G1CollectedHeap interface is
 //   serialized by acquiring the HeapLock.  This happens in
 //   mem_allocate_work, which all such allocation functions call.
 //   (Note that this does not apply to TLAB allocation, which is not part
 //   of this interface: it is done by clients of this interface.)
 // Local to this file.
 class RefineCardTableEntryClosure: public CardTableEntryClosure {
   SuspendibleThreadSet* _sts;
   G1RemSet* _g1rs;
   ConcurrentG1Refine* _cg1r;
   bool _concurrent;
 public:
   RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
                               G1RemSet* g1rs,
                               ConcurrentG1Refine* cg1r) :
     _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
   {}
   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
     bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
     // This path is executed by the concurrent refine or mutator threads,
     // concurrently, and so we do not care if card_ptr contains references
     // that point into the collection set.
     assert(!oops_into_cset, "should be");
     if (_concurrent && _sts->should_yield()) {
       // Caller will actually yield.
       return false;
     }
     // Otherwise, we finished successfully; return true.
     return true;
   }
   void set_concurrent(bool b) { _concurrent = b; }
 };
 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
   int _calls;
   G1CollectedHeap* _g1h;
   CardTableModRefBS* _ctbs;
   int _histo[256];
 public:
   ClearLoggedCardTableEntryClosure() :
     _calls(0)
   {
     _g1h = G1CollectedHeap::heap();
     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
     for (int i = 0; i < 256; i++) _histo[i] = 0;
   }
   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
       _calls++;
       unsigned char* ujb = (unsigned char*)card_ptr;
       int ind = (int)(*ujb);
       _histo[ind]++;
       *card_ptr = -1;
     }
     return true;
   }
   int calls() { return _calls; }
   void print_histo() {
     gclog_or_tty->print_cr("Card table value histogram:");
     for (int i = 0; i < 256; i++) {
       if (_histo[i] != 0) {
         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
       }
     }
   }
 };
 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
   int _calls;
   G1CollectedHeap* _g1h;
   CardTableModRefBS* _ctbs;
 public:
   RedirtyLoggedCardTableEntryClosure() :
     _calls(0)
   {
     _g1h = G1CollectedHeap::heap();
     _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
   }
   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
     if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
       _calls++;
       *card_ptr = 0;
     }
     return true;
   }
   int calls() { return _calls; }
 };
 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
 public:
   bool do_card_ptr(jbyte* card_ptr, int worker_i) {
     *card_ptr = CardTableModRefBS::dirty_card_val();
     return true;
   }
 };
 YoungList::YoungList(G1CollectedHeap* g1h)
   : _g1h(g1h), _head(NULL),
     _length(0),
     _last_sampled_rs_lengths(0),
     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
 {
   guarantee( check_list_empty(false), "just making sure..." );
 }
 void YoungList::push_region(HeapRegion *hr) {
   assert(!hr->is_young(), "should not already be young");
   assert(hr->get_next_young_region() == NULL, "cause it should!");
   hr->set_next_young_region(_head);
   _head = hr;
   hr->set_young();
   double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
   ++_length;
 }
 void YoungList::add_survivor_region(HeapRegion* hr) {
   assert(hr->is_survivor(), "should be flagged as survivor region");
   assert(hr->get_next_young_region() == NULL, "cause it should!");
   hr->set_next_young_region(_survivor_head);
   if (_survivor_head == NULL) {
     _survivor_tail = hr;
   }
   _survivor_head = hr;
   ++_survivor_length;
 }
 void YoungList::empty_list(HeapRegion* list) {
   while (list != NULL) {
     HeapRegion* next = list->get_next_young_region();
     list->set_next_young_region(NULL);
     list->uninstall_surv_rate_group();
     list->set_not_young();
     list = next;
   }
 }
 void YoungList::empty_list() {
   assert(check_list_well_formed(), "young list should be well formed");
   empty_list(_head);
   _head = NULL;
   _length = 0;
   empty_list(_survivor_head);
   _survivor_head = NULL;
   _survivor_tail = NULL;
   _survivor_length = 0;
   _last_sampled_rs_lengths = 0;
   assert(check_list_empty(false), "just making sure...");
 }
 bool YoungList::check_list_well_formed() {
   bool ret = true;
   size_t length = 0;
   HeapRegion* curr = _head;
   HeapRegion* last = NULL;
   while (curr != NULL) {
     if (!curr->is_young()) {
       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
                              "incorrectly tagged (y: %d, surv: %d)",
                              curr->bottom(), curr->end(),
                              curr->is_young(), curr->is_survivor());
       ret = false;
     }
     ++length;
     last = curr;
     curr = curr->get_next_young_region();
   }
   ret = ret && (length == _length);
   if (!ret) {
     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
     gclog_or_tty->print_cr("###   list has %d entries, _length is %d",
                            length, _length);
   }
   return ret;
 }
 bool YoungList::check_list_empty(bool check_sample) {
   bool ret = true;
   if (_length != 0) {
     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
                   _length);
     ret = false;
   }
   if (check_sample && _last_sampled_rs_lengths != 0) {
     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
     ret = false;
   }
   if (_head != NULL) {
     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
     ret = false;
   }
   if (!ret) {
     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
   }
   return ret;
 }
 void
 YoungList::rs_length_sampling_init() {
   _sampled_rs_lengths = 0;
   _curr               = _head;
 }
 bool
 YoungList::rs_length_sampling_more() {
   return _curr != NULL;
 }
 void
 YoungList::rs_length_sampling_next() {
   assert( _curr != NULL, "invariant" );
   size_t rs_length = _curr->rem_set()->occupied();
   _sampled_rs_lengths += rs_length;
   // The current region may not yet have been added to the
   // incremental collection set (it gets added when it is
   // retired as the current allocation region).
   if (_curr->in_collection_set()) {
     // Update the collection set policy information for this region
     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
   }
   _curr = _curr->get_next_young_region();
   if (_curr == NULL) {
     _last_sampled_rs_lengths = _sampled_rs_lengths;
     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
   }
 }
 void
 YoungList::reset_auxilary_lists() {
   guarantee( is_empty(), "young list should be empty" );
   assert(check_list_well_formed(), "young list should be well formed");
   // Add survivor regions to SurvRateGroup.
   _g1h->g1_policy()->note_start_adding_survivor_regions();
   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
   for (HeapRegion* curr = _survivor_head;
        curr != NULL;
        curr = curr->get_next_young_region()) {
     _g1h->g1_policy()->set_region_survivors(curr);
     // The region is a non-empty survivor so let's add it to
     // the incremental collection set for the next evacuation
     // pause.
     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
   }
   _g1h->g1_policy()->note_stop_adding_survivor_regions();
   _head   = _survivor_head;
   _length = _survivor_length;
   if (_survivor_head != NULL) {
     assert(_survivor_tail != NULL, "cause it shouldn't be");
     assert(_survivor_length > 0, "invariant");
     _survivor_tail->set_next_young_region(NULL);
   }
   // Don't clear the survivor list handles until the start of
   // the next evacuation pause - we need it in order to re-tag
   // the survivor regions from this evacuation pause as 'young'
   // at the start of the next.
   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
   assert(check_list_well_formed(), "young list should be well formed");
 }
 void YoungList::print() {
   HeapRegion* lists[] = {_head,   _survivor_head};
   const char* names[] = {"YOUNG", "SURVIVOR"};
   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
     HeapRegion *curr = lists[list];
     if (curr == NULL)
       gclog_or_tty->print_cr("  empty");
     while (curr != NULL) {
       gclog_or_tty->print_cr("  [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
                              "age: %4d, y: %d, surv: %d",
                              curr->bottom(), curr->end(),
                              curr->top(),
                              curr->prev_top_at_mark_start(),
                              curr->next_top_at_mark_start(),
                              curr->top_at_conc_mark_count(),
                              curr->age_in_surv_rate_group_cond(),
                              curr->is_young(),
                              curr->is_survivor());
       curr = curr->get_next_young_region();
     }
   }
   gclog_or_tty->print_cr("");
 }
 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 {
   // Claim the right to put the region on the dirty cards region list
   // by installing a self pointer.
   HeapRegion* next = hr->get_next_dirty_cards_region();
   if (next == NULL) {
     HeapRegion* res = (HeapRegion*)
       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
                           NULL);
     if (res == NULL) {
       HeapRegion* head;
       do {
         // Put the region to the dirty cards region list.
         head = _dirty_cards_region_list;
         next = (HeapRegion*)
           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
         if (next == head) {
           assert(hr->get_next_dirty_cards_region() == hr,
                  "hr->get_next_dirty_cards_region() != hr");
           if (next == NULL) {
             // The last region in the list points to itself.
             hr->set_next_dirty_cards_region(hr);
           } else {
             hr->set_next_dirty_cards_region(next);
           }
         }
       } while (next != head);
     }
   }
 }
 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 {
   HeapRegion* head;
   HeapRegion* hr;
   do {
     head = _dirty_cards_region_list;
     if (head == NULL) {
       return NULL;
     }
     HeapRegion* new_head = head->get_next_dirty_cards_region();
     if (head == new_head) {
       // The last region.
       new_head = NULL;
     }
     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
                                           head);
   } while (hr != head);
   assert(hr != NULL, "invariant");
   hr->set_next_dirty_cards_region(NULL);
   return hr;
 }
 void G1CollectedHeap::stop_conc_gc_threads() {
   _cg1r->stop();
   _czft->stop();
   _cmThread->stop();
 }
 void G1CollectedHeap::check_ct_logs_at_safepoint() {
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
   // Count the dirty cards at the start.
   CountNonCleanMemRegionClosure count1(this);
   ct_bs->mod_card_iterate(&count1);
   int orig_count = count1.n();
   // First clear the logged cards.
   ClearLoggedCardTableEntryClosure clear;
   dcqs.set_closure(&clear);
   dcqs.apply_closure_to_all_completed_buffers();
   dcqs.iterate_closure_all_threads(false);
   clear.print_histo();
   // Now ensure that there's no dirty cards.
   CountNonCleanMemRegionClosure count2(this);
   ct_bs->mod_card_iterate(&count2);
   if (count2.n() != 0) {
     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
                            count2.n(), orig_count);
   }
   guarantee(count2.n() == 0, "Card table should be clean.");
   RedirtyLoggedCardTableEntryClosure redirty;
   JavaThread::dirty_card_queue_set().set_closure(&redirty);
   dcqs.apply_closure_to_all_completed_buffers();
   dcqs.iterate_closure_all_threads(false);
   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
                          clear.calls(), orig_count);
   guarantee(redirty.calls() == clear.calls(),
             "Or else mechanism is broken.");
   CountNonCleanMemRegionClosure count3(this);
   ct_bs->mod_card_iterate(&count3);
   if (count3.n() != orig_count) {
     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
                            orig_count, count3.n());
     guarantee(count3.n() >= orig_count, "Should have restored them all.");
   }
   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
 }
 // Private class members.
 G1CollectedHeap* G1CollectedHeap::_g1h;
 // Private methods.
 // Finds a HeapRegion that can be used to allocate a given size of block.
 HeapRegion* G1CollectedHeap::newAllocRegion_work(size_t word_size,
                                                  bool do_expand,
                                                  bool zero_filled) {
   ConcurrentZFThread::note_region_alloc();
   HeapRegion* res = alloc_free_region_from_lists(zero_filled);
   if (res == NULL && do_expand) {
     expand(word_size * HeapWordSize);
     res = alloc_free_region_from_lists(zero_filled);
     assert(res == NULL ||
            (!res->isHumongous() &&
             (!zero_filled ||
              res->zero_fill_state() == HeapRegion::Allocated)),
            "Alloc Regions must be zero filled (and non-H)");
   }
   if (res != NULL) {
     if (res->is_empty()) {
       _free_regions--;
     }
     assert(!res->isHumongous() &&
            (!zero_filled || res->zero_fill_state() == HeapRegion::Allocated),
            err_msg("Non-young alloc Regions must be zero filled (and non-H):"
                    " res->isHumongous()=%d, zero_filled=%d, res->zero_fill_state()=%d",
                    res->isHumongous(), zero_filled, res->zero_fill_state()));
     assert(!res->is_on_unclean_list(),
            "Alloc Regions must not be on the unclean list");
     if (G1PrintHeapRegions) {
       gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
                              "top "PTR_FORMAT,
                              res->hrs_index(), res->bottom(), res->end(), res->top());
     }
   }
   return res;
 }
 HeapRegion* G1CollectedHeap::newAllocRegionWithExpansion(int purpose,
                                                          size_t word_size,
                                                          bool zero_filled) {
   HeapRegion* alloc_region = NULL;
   if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
     alloc_region = newAllocRegion_work(word_size, true, zero_filled);
     if (purpose == GCAllocForSurvived && alloc_region != NULL) {
       alloc_region->set_survivor();
     }
     ++_gc_alloc_region_counts[purpose];
   } else {
     g1_policy()->note_alloc_region_limit_reached(purpose);
   }
   return alloc_region;
 }
 // If could fit into free regions w/o expansion, try.
 // Otherwise, if can expand, do so.
 // Otherwise, if using ex regions might help, try with ex given back.
 HeapWord* G1CollectedHeap::humongousObjAllocate(size_t word_size) {
   assert(regions_accounted_for(), "Region leakage!");
   // We can't allocate H regions while cleanupComplete is running, since
   // some of the regions we find to be empty might not yet be added to the
   // unclean list.  (If we're already at a safepoint, this call is
   // unnecessary, not to mention wrong.)
   if (!SafepointSynchronize::is_at_safepoint())
     wait_for_cleanup_complete();
   size_t num_regions =
     round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
   // Special case if < one region???
   // Remember the ft size.
   size_t x_size = expansion_regions();
   HeapWord* res = NULL;
   bool eliminated_allocated_from_lists = false;
   // Can the allocation potentially fit in the free regions?
   if (free_regions() >= num_regions) {
     res = _hrs->obj_allocate(word_size);
   }
   if (res == NULL) {
     // Try expansion.
     size_t fs = _hrs->free_suffix();
     if (fs + x_size >= num_regions) {
       expand((num_regions - fs) * HeapRegion::GrainBytes);
       res = _hrs->obj_allocate(word_size);
       assert(res != NULL, "This should have worked.");
     } else {
       // Expansion won't help.  Are there enough free regions if we get rid
       // of reservations?
       size_t avail = free_regions();
       if (avail >= num_regions) {
         res = _hrs->obj_allocate(word_size);
         if (res != NULL) {
           remove_allocated_regions_from_lists();
           eliminated_allocated_from_lists = true;
         }
       }
     }
   }
   if (res != NULL) {
     // Increment by the number of regions allocated.
     // FIXME: Assumes regions all of size GrainBytes.
 #ifndef PRODUCT
     mr_bs()->verify_clean_region(MemRegion(res, res + num_regions *
                                            HeapRegion::GrainWords));
 #endif
     if (!eliminated_allocated_from_lists)
       remove_allocated_regions_from_lists();
     _summary_bytes_used += word_size * HeapWordSize;
     _free_regions -= num_regions;
     _num_humongous_regions += (int) num_regions;
   }
   assert(regions_accounted_for(), "Region Leakage");
   return res;
 }
 HeapWord*
 G1CollectedHeap::attempt_allocation_slow(size_t word_size,
                                          bool permit_collection_pause) {
   HeapWord* res = NULL;
   HeapRegion* allocated_young_region = NULL;
   assert( SafepointSynchronize::is_at_safepoint() ||
           Heap_lock->owned_by_self(), "pre condition of the call" );
   if (isHumongous(word_size)) {
     // Allocation of a humongous object can, in a sense, complete a
     // partial region, if the previous alloc was also humongous, and
     // caused the test below to succeed.
     if (permit_collection_pause)
       do_collection_pause_if_appropriate(word_size);
     res = humongousObjAllocate(word_size);
     assert(_cur_alloc_region == NULL
            || !_cur_alloc_region->isHumongous(),
            "Prevent a regression of this bug.");
   } else {
     // We may have concurrent cleanup working at the time. Wait for it
     // to complete. In the future we would probably want to make the
     // concurrent cleanup truly concurrent by decoupling it from the
     // allocation.
     if (!SafepointSynchronize::is_at_safepoint())
       wait_for_cleanup_complete();
     // If we do a collection pause, this will be reset to a non-NULL
     // value.  If we don't, nulling here ensures that we allocate a new
     // region below.
     if (_cur_alloc_region != NULL) {
       // We're finished with the _cur_alloc_region.
       // As we're builing (at least the young portion) of the collection
       // set incrementally we'll add the current allocation region to
       // the collection set here.
       if (_cur_alloc_region->is_young()) {
         g1_policy()->add_region_to_incremental_cset_lhs(_cur_alloc_region);
       }
       _summary_bytes_used += _cur_alloc_region->used();
       _cur_alloc_region = NULL;
     }
     assert(_cur_alloc_region == NULL, "Invariant.");
     // Completion of a heap region is perhaps a good point at which to do
     // a collection pause.
     if (permit_collection_pause)
       do_collection_pause_if_appropriate(word_size);
     // Make sure we have an allocation region available.
     if (_cur_alloc_region == NULL) {
       if (!SafepointSynchronize::is_at_safepoint())
         wait_for_cleanup_complete();
       bool next_is_young = should_set_young_locked();
       // If the next region is not young, make sure it's zero-filled.
       _cur_alloc_region = newAllocRegion(word_size, !next_is_young);
       if (_cur_alloc_region != NULL) {
         _summary_bytes_used -= _cur_alloc_region->used();
         if (next_is_young) {
           set_region_short_lived_locked(_cur_alloc_region);
           allocated_young_region = _cur_alloc_region;
         }
       }
     }
     assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
            "Prevent a regression of this bug.");
     // Now retry the allocation.
     if (_cur_alloc_region != NULL) {
       if (allocated_young_region != NULL) {
         // We need to ensure that the store to top does not
         // float above the setting of the young type.
         OrderAccess::storestore();
       }
       res = _cur_alloc_region->allocate(word_size);
     }
   }
   // NOTE: fails frequently in PRT
   assert(regions_accounted_for(), "Region leakage!");
   if (res != NULL) {
     if (!SafepointSynchronize::is_at_safepoint()) {
       assert( permit_collection_pause, "invariant" );
       assert( Heap_lock->owned_by_self(), "invariant" );
       Heap_lock->unlock();
     }
     if (allocated_young_region != NULL) {
       HeapRegion* hr = allocated_young_region;
       HeapWord* bottom = hr->bottom();
       HeapWord* end = hr->end();
       MemRegion mr(bottom, end);
       ((CardTableModRefBS*)_g1h->barrier_set())->dirty(mr);
     }
   }
   assert( SafepointSynchronize::is_at_safepoint() ||
           (res == NULL && Heap_lock->owned_by_self()) ||
           (res != NULL && !Heap_lock->owned_by_self()),
           "post condition of the call" );
   return res;
 }
 HeapWord*
 G1CollectedHeap::mem_allocate(size_t word_size,
                               bool   is_noref,
                               bool   is_tlab,
                               bool* gc_overhead_limit_was_exceeded) {
   debug_only(check_for_valid_allocation_state());
   assert(no_gc_in_progress(), "Allocation during gc not allowed");
   HeapWord* result = NULL;
   // Loop until the allocation is satisified,
   // or unsatisfied after GC.
   for (int try_count = 1; /* return or throw */; try_count += 1) {
     int gc_count_before;
     {
       Heap_lock->lock();
       result = attempt_allocation(word_size);
       if (result != NULL) {
         // attempt_allocation should have unlocked the heap lock
         assert(is_in(result), "result not in heap");
         return result;
       }
       // Read the gc count while the heap lock is held.
       gc_count_before = SharedHeap::heap()->total_collections();
       Heap_lock->unlock();
     }
     // Create the garbage collection operation...
     VM_G1CollectForAllocation op(word_size,
                                  gc_count_before);
     // ...and get the VM thread to execute it.
     VMThread::execute(&op);
     if (op.prologue_succeeded()) {
       result = op.result();
       assert(result == NULL || is_in(result), "result not in heap");
       return result;
     }
     // Give a warning if we seem to be looping forever.
     if ((QueuedAllocationWarningCount > 0) &&
         (try_count % QueuedAllocationWarningCount == 0)) {
       warning("G1CollectedHeap::mem_allocate_work retries %d times",
               try_count);
     }
   }
 }
 void G1CollectedHeap::abandon_cur_alloc_region() {
   if (_cur_alloc_region != NULL) {
     // We're finished with the _cur_alloc_region.
     if (_cur_alloc_region->is_empty()) {
       _free_regions++;
       free_region(_cur_alloc_region);
     } else {
       // As we're builing (at least the young portion) of the collection
       // set incrementally we'll add the current allocation region to
       // the collection set here.
       if (_cur_alloc_region->is_young()) {
         g1_policy()->add_region_to_incremental_cset_lhs(_cur_alloc_region);
       }
       _summary_bytes_used += _cur_alloc_region->used();
     }
     _cur_alloc_region = NULL;
   }
 }
 void G1CollectedHeap::abandon_gc_alloc_regions() {
   // first, make sure that the GC alloc region list is empty (it should!)
   assert(_gc_alloc_region_list == NULL, "invariant");
   release_gc_alloc_regions(true /* totally */);
 }
 class PostMCRemSetClearClosure: public HeapRegionClosure {
   ModRefBarrierSet* _mr_bs;
 public:
   PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
   bool doHeapRegion(HeapRegion* r) {
     r->reset_gc_time_stamp();
     if (r->continuesHumongous())
       return false;
     HeapRegionRemSet* hrrs = r->rem_set();
     if (hrrs != NULL) hrrs->clear();
     // You might think here that we could clear just the cards
     // corresponding to the used region.  But no: if we leave a dirty card
     // in a region we might allocate into, then it would prevent that card
     // from being enqueued, and cause it to be missed.
     // Re: the performance cost: we shouldn't be doing full GC anyway!
     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
     return false;
   }
 };
 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
   ModRefBarrierSet* _mr_bs;
 public:
   PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
   bool doHeapRegion(HeapRegion* r) {
     if (r->continuesHumongous()) return false;
     if (r->used_region().word_size() != 0) {
       _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
     }
     return false;
   }
 };
 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
   G1CollectedHeap*   _g1h;
   UpdateRSOopClosure _cl;
   int                _worker_i;
 public:
   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
     _cl(g1->g1_rem_set()->as_HRInto_G1RemSet(), worker_i),
     _worker_i(worker_i),
     _g1h(g1)
   { }
   bool doHeapRegion(HeapRegion* r) {
     if (!r->continuesHumongous()) {
       _cl.set_from(r);
       r->oop_iterate(&_cl);
     }
     return false;
   }
 };
 class ParRebuildRSTask: public AbstractGangTask {
   G1CollectedHeap* _g1;
 public:
   ParRebuildRSTask(G1CollectedHeap* g1)
     : AbstractGangTask("ParRebuildRSTask"),
       _g1(g1)
   { }
   void work(int i) {
     RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
     _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
                                          HeapRegion::RebuildRSClaimValue);
   }
 };
 void G1CollectedHeap::do_collection(bool explicit_gc,
                                     bool clear_all_soft_refs,
                                     size_t word_size) {
   if (GC_locker::check_active_before_gc()) {
     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
   }
   ResourceMark rm;
   if (PrintHeapAtGC) {
     Universe::print_heap_before_gc();
   }
   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
   assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
                            collector_policy()->should_clear_all_soft_refs();
   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
   {
     IsGCActiveMark x;
     // Timing
     bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
     assert(!system_gc || explicit_gc, "invariant");
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
     TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
                 PrintGC, true, gclog_or_tty);
     TraceMemoryManagerStats tms(true /* fullGC */);
     double start = os::elapsedTime();
     g1_policy()->record_full_collection_start();
     gc_prologue(true);
     increment_total_collections(true /* full gc */);
     size_t g1h_prev_used = used();
     assert(used() == recalculate_used(), "Should be equal");
     if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
       HandleMark hm;  // Discard invalid handles created during verification
       prepare_for_verify();
       gclog_or_tty->print(" VerifyBeforeGC:");
       Universe::verify(true);
     }
     assert(regions_accounted_for(), "Region leakage!");
     COMPILER2_PRESENT(DerivedPointerTable::clear());
     // We want to discover references, but not process them yet.
     // This mode is disabled in
     // instanceRefKlass::process_discovered_references if the
     // generation does some collection work, or
     // instanceRefKlass::enqueue_discovered_references if the
     // generation returns without doing any work.
     ref_processor()->disable_discovery();
     ref_processor()->abandon_partial_discovery();
     ref_processor()->verify_no_references_recorded();
     // Abandon current iterations of concurrent marking and concurrent
     // refinement, if any are in progress.
     concurrent_mark()->abort();
     // Make sure we'll choose a new allocation region afterwards.
     abandon_cur_alloc_region();
     abandon_gc_alloc_regions();
     assert(_cur_alloc_region == NULL, "Invariant.");
     g1_rem_set()->as_HRInto_G1RemSet()->cleanupHRRS();
     tear_down_region_lists();
     set_used_regions_to_need_zero_fill();
     // We may have added regions to the current incremental collection
     // set between the last GC or pause and now. We need to clear the
     // incremental collection set and then start rebuilding it afresh
     // after this full GC.
     abandon_collection_set(g1_policy()->inc_cset_head());
     g1_policy()->clear_incremental_cset();
     g1_policy()->stop_incremental_cset_building();
     if (g1_policy()->in_young_gc_mode()) {
       empty_young_list();
       g1_policy()->set_full_young_gcs(true);
     }
     // Temporarily make reference _discovery_ single threaded (non-MT).
     ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
     // Temporarily make refs discovery atomic
     ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
     // Temporarily clear _is_alive_non_header
     ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
     ref_processor()->enable_discovery();
     ref_processor()->setup_policy(do_clear_all_soft_refs);
     // Do collection work
     {
       HandleMark hm;  // Discard invalid handles created during gc
       G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
     }
     // Because freeing humongous regions may have added some unclean
     // regions, it is necessary to tear down again before rebuilding.
     tear_down_region_lists();
     rebuild_region_lists();
     _summary_bytes_used = recalculate_used();
     ref_processor()->enqueue_discovered_references();
     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
     MemoryService::track_memory_usage();
     if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
       HandleMark hm;  // Discard invalid handles created during verification
       gclog_or_tty->print(" VerifyAfterGC:");
       prepare_for_verify();
       Universe::verify(false);
     }
     NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
     reset_gc_time_stamp();
     // Since everything potentially moved, we will clear all remembered
     // sets, and clear all cards.  Later we will rebuild remebered
     // sets. We will also reset the GC time stamps of the regions.
     PostMCRemSetClearClosure rs_clear(mr_bs());
     heap_region_iterate(&rs_clear);
     // Resize the heap if necessary.
     resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
     if (_cg1r->use_cache()) {
       _cg1r->clear_and_record_card_counts();
       _cg1r->clear_hot_cache();
     }
     // Rebuild remembered sets of all regions.
     if (ParallelGCThreads > 0) {
       ParRebuildRSTask rebuild_rs_task(this);
       assert(check_heap_region_claim_values(
              HeapRegion::InitialClaimValue), "sanity check");
       set_par_threads(workers()->total_workers());
       workers()->run_task(&rebuild_rs_task);
       set_par_threads(0);
       assert(check_heap_region_claim_values(
              HeapRegion::RebuildRSClaimValue), "sanity check");
       reset_heap_region_claim_values();
     } else {
       RebuildRSOutOfRegionClosure rebuild_rs(this);
       heap_region_iterate(&rebuild_rs);
     }
     if (PrintGC) {
       print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
     }
     if (true) { // FIXME
       // Ask the permanent generation to adjust size for full collections
       perm()->compute_new_size();
     }
     // Start a new incremental collection set for the next pause
     assert(g1_policy()->collection_set() == NULL, "must be");
     g1_policy()->start_incremental_cset_building();
     // Clear the _cset_fast_test bitmap in anticipation of adding
     // regions to the incremental collection set for the next
     // evacuation pause.
     clear_cset_fast_test();
     double end = os::elapsedTime();
     g1_policy()->record_full_collection_end();
 #ifdef TRACESPINNING
     ParallelTaskTerminator::print_termination_counts();
 #endif
     gc_epilogue(true);
     // Discard all rset updates
     JavaThread::dirty_card_queue_set().abandon_logs();
     assert(!G1DeferredRSUpdate
            || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
     assert(regions_accounted_for(), "Region leakage!");
   }
   if (g1_policy()->in_young_gc_mode()) {
     _young_list->reset_sampled_info();
     // At this point there should be no regions in the
     // entire heap tagged as young.
     assert( check_young_list_empty(true /* check_heap */),
             "young list should be empty at this point");
   }
   // Update the number of full collections that have been completed.
   increment_full_collections_completed(false /* outer */);
   if (PrintHeapAtGC) {
     Universe::print_heap_after_gc();
   }
 }
 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
   do_collection(true,                /* explicit_gc */
                 clear_all_soft_refs,
 /* word_size */);
 }
 // This code is mostly copied from TenuredGeneration.
 void
 G1CollectedHeap::
 resize_if_necessary_after_full_collection(size_t word_size) {
   assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
   // Include the current allocation, if any, and bytes that will be
   // pre-allocated to support collections, as "used".
   const size_t used_after_gc = used();
   const size_t capacity_after_gc = capacity();
   const size_t free_after_gc = capacity_after_gc - used_after_gc;
   // We don't have floating point command-line arguments
   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
   size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
   size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
   // Don't shrink less than the initial size.
   minimum_desired_capacity =
     MAX2(minimum_desired_capacity,
          collector_policy()->initial_heap_byte_size());
   maximum_desired_capacity =
     MAX2(maximum_desired_capacity,
          collector_policy()->initial_heap_byte_size());
   // We are failing here because minimum_desired_capacity is
   assert(used_after_gc <= minimum_desired_capacity, "sanity check");
   assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
   if (PrintGC && Verbose) {
     const double free_percentage = ((double)free_after_gc) / capacity();
     gclog_or_tty->print_cr("Computing new size after full GC ");
     gclog_or_tty->print_cr("  "
                            "  minimum_free_percentage: %6.2f",
                            minimum_free_percentage);
     gclog_or_tty->print_cr("  "
                            "  maximum_free_percentage: %6.2f",
                            maximum_free_percentage);
     gclog_or_tty->print_cr("  "
                            "  capacity: %6.1fK"
                            "  minimum_desired_capacity: %6.1fK"
                            "  maximum_desired_capacity: %6.1fK",
                            capacity() / (double) K,
                            minimum_desired_capacity / (double) K,
                            maximum_desired_capacity / (double) K);
     gclog_or_tty->print_cr("  "
                            "   free_after_gc   : %6.1fK"
                            "   used_after_gc   : %6.1fK",
                            free_after_gc / (double) K,
                            used_after_gc / (double) K);
     gclog_or_tty->print_cr("  "
                            "   free_percentage: %6.2f",
                            free_percentage);
   }
   if (capacity() < minimum_desired_capacity) {
     // Don't expand unless it's significant
     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
     expand(expand_bytes);
     if (PrintGC && Verbose) {
       gclog_or_tty->print_cr("    expanding:"
                              "  minimum_desired_capacity: %6.1fK"
                              "  expand_bytes: %6.1fK",
                              minimum_desired_capacity / (double) K,
                              expand_bytes / (double) K);
     }
     // No expansion, now see if we want to shrink
   } else if (capacity() > maximum_desired_capacity) {
     // Capacity too large, compute shrinking size
     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
     shrink(shrink_bytes);
     if (PrintGC && Verbose) {
       gclog_or_tty->print_cr("  "
                              "  shrinking:"
                              "  initSize: %.1fK"
                              "  maximum_desired_capacity: %.1fK",
                              collector_policy()->initial_heap_byte_size() / (double) K,
                              maximum_desired_capacity / (double) K);
       gclog_or_tty->print_cr("  "
                              "  shrink_bytes: %.1fK",
                              shrink_bytes / (double) K);
     }
   }
 }
 HeapWord*
 G1CollectedHeap::satisfy_failed_allocation(size_t word_size) {
   HeapWord* result = NULL;
   // In a G1 heap, we're supposed to keep allocation from failing by
   // incremental pauses.  Therefore, at least for now, we'll favor
   // expansion over collection.  (This might change in the future if we can
   // do something smarter than full collection to satisfy a failed alloc.)
   result = expand_and_allocate(word_size);
   if (result != NULL) {
     assert(is_in(result), "result not in heap");
     return result;
   }
   // OK, I guess we have to try collection.
   do_collection(false, false, word_size);
   result = attempt_allocation(word_size, /*permit_collection_pause*/false);
   if (result != NULL) {
     assert(is_in(result), "result not in heap");
     return result;
   }
   // Try collecting soft references.
   do_collection(false, true, word_size);
   result = attempt_allocation(word_size, /*permit_collection_pause*/false);
   if (result != NULL) {
     assert(is_in(result), "result not in heap");
     return result;
   }
   assert(!collector_policy()->should_clear_all_soft_refs(),
     "Flag should have been handled and cleared prior to this point");
   // What else?  We might try synchronous finalization later.  If the total
   // space available is large enough for the allocation, then a more
   // complete compaction phase than we've tried so far might be
   // appropriate.
   return NULL;
 }
 // Attempting to expand the heap sufficiently
 // to support an allocation of the given "word_size".  If
 // successful, perform the allocation and return the address of the
 // allocated block, or else "NULL".
 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
   size_t expand_bytes = word_size * HeapWordSize;
   if (expand_bytes < MinHeapDeltaBytes) {
     expand_bytes = MinHeapDeltaBytes;
   }
   expand(expand_bytes);
   assert(regions_accounted_for(), "Region leakage!");
   HeapWord* result = attempt_allocation(word_size, false /* permit_collection_pause */);
   return result;
 }
 size_t G1CollectedHeap::free_region_if_totally_empty(HeapRegion* hr) {
   size_t pre_used = 0;
   size_t cleared_h_regions = 0;
   size_t freed_regions = 0;
   UncleanRegionList local_list;
   free_region_if_totally_empty_work(hr, pre_used, cleared_h_regions,
                                     freed_regions, &local_list);
   finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
                           &local_list);
   return pre_used;
 }
 void
 G1CollectedHeap::free_region_if_totally_empty_work(HeapRegion* hr,
                                                    size_t& pre_used,
                                                    size_t& cleared_h,
                                                    size_t& freed_regions,
                                                    UncleanRegionList* list,
                                                    bool par) {
   assert(!hr->continuesHumongous(), "should have filtered these out");
   size_t res = 0;
   if (hr->used() > 0 && hr->garbage_bytes() == hr->used() &&
       !hr->is_young()) {
     if (G1PolicyVerbose > 0)
       gclog_or_tty->print_cr("Freeing empty region "PTR_FORMAT "(" SIZE_FORMAT " bytes)"
                                                                                " during cleanup", hr, hr->used());
     free_region_work(hr, pre_used, cleared_h, freed_regions, list, par);
   }
 }
 // FIXME: both this and shrink could probably be more efficient by
 // doing one "VirtualSpace::expand_by" call rather than several.
 void G1CollectedHeap::expand(size_t expand_bytes) {
   size_t old_mem_size = _g1_storage.committed_size();
   // We expand by a minimum of 1K.
   expand_bytes = MAX2(expand_bytes, (size_t)K);
   size_t aligned_expand_bytes =
     ReservedSpace::page_align_size_up(expand_bytes);
   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
                                        HeapRegion::GrainBytes);
   expand_bytes = aligned_expand_bytes;
   while (expand_bytes > 0) {
     HeapWord* base = (HeapWord*)_g1_storage.high();
     // Commit more storage.
     bool successful = _g1_storage.expand_by(HeapRegion::GrainBytes);
     if (!successful) {
         expand_bytes = 0;
     } else {
       expand_bytes -= HeapRegion::GrainBytes;
       // Expand the committed region.
       HeapWord* high = (HeapWord*) _g1_storage.high();
       _g1_committed.set_end(high);
       // Create a new HeapRegion.
       MemRegion mr(base, high);
       bool is_zeroed = !_g1_max_committed.contains(base);
       HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
       // Now update max_committed if necessary.
       _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), high));
       // Add it to the HeapRegionSeq.
       _hrs->insert(hr);
       // Set the zero-fill state, according to whether it's already
       // zeroed.
       {
         MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
         if (is_zeroed) {
           hr->set_zero_fill_complete();
           put_free_region_on_list_locked(hr);
         } else {
           hr->set_zero_fill_needed();
           put_region_on_unclean_list_locked(hr);
         }
       }
       _free_regions++;
       // And we used up an expansion region to create it.
       _expansion_regions--;
       // Tell the cardtable about it.
       Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
       // And the offset table as well.
       _bot_shared->resize(_g1_committed.word_size());
     }
   }
   if (Verbose && PrintGC) {
     size_t new_mem_size = _g1_storage.committed_size();
     gclog_or_tty->print_cr("Expanding garbage-first heap from %ldK by %ldK to %ldK",
                            old_mem_size/K, aligned_expand_bytes/K,
                            new_mem_size/K);
   }
 }
 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
 {
   size_t old_mem_size = _g1_storage.committed_size();
   size_t aligned_shrink_bytes =
     ReservedSpace::page_align_size_down(shrink_bytes);
   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
                                          HeapRegion::GrainBytes);
   size_t num_regions_deleted = 0;
   MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
   assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
   if (mr.byte_size() > 0)
     _g1_storage.shrink_by(mr.byte_size());
   assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
   _g1_committed.set_end(mr.start());
   _free_regions -= num_regions_deleted;
   _expansion_regions += num_regions_deleted;
   // Tell the cardtable about it.
   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
   // And the offset table as well.
   _bot_shared->resize(_g1_committed.word_size());
   HeapRegionRemSet::shrink_heap(n_regions());
   if (Verbose && PrintGC) {
     size_t new_mem_size = _g1_storage.committed_size();
     gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
                            old_mem_size/K, aligned_shrink_bytes/K,
                            new_mem_size/K);
   }
 }
 void G1CollectedHeap::shrink(size_t shrink_bytes) {
   release_gc_alloc_regions(true /* totally */);
   tear_down_region_lists();  // We will rebuild them in a moment.
   shrink_helper(shrink_bytes);
   rebuild_region_lists();
 }
 // Public methods.
 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 #endif // _MSC_VER
 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
   SharedHeap(policy_),
   _g1_policy(policy_),
   _dirty_card_queue_set(false),
   _into_cset_dirty_card_queue_set(false),
   _ref_processor(NULL),
   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
   _bot_shared(NULL),
   _par_alloc_during_gc_lock(Mutex::leaf, "par alloc during GC lock"),
   _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
   _evac_failure_scan_stack(NULL) ,
   _mark_in_progress(false),
   _cg1r(NULL), _czft(NULL), _summary_bytes_used(0),
   _cur_alloc_region(NULL),
   _refine_cte_cl(NULL),
   _free_region_list(NULL), _free_region_list_size(0),
   _free_regions(0),
   _full_collection(false),
   _unclean_region_list(),
   _unclean_regions_coming(false),
   _young_list(new YoungList(this)),
   _gc_time_stamp(0),
   _surviving_young_words(NULL),
   _full_collections_completed(0),
   _in_cset_fast_test(NULL),
   _in_cset_fast_test_base(NULL),
   _dirty_cards_region_list(NULL) {
   _g1h = this; // To catch bugs.
   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
     vm_exit_during_initialization("Failed necessary allocation.");
   }
   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
   int n_queues = MAX2((int)ParallelGCThreads, 1);
   _task_queues = new RefToScanQueueSet(n_queues);
   int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
   assert(n_rem_sets > 0, "Invariant.");
   HeapRegionRemSetIterator** iter_arr =
     NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
   for (int i = 0; i < n_queues; i++) {
     iter_arr[i] = new HeapRegionRemSetIterator();
   }
   _rem_set_iterator = iter_arr;
   for (int i = 0; i < n_queues; i++) {
     RefToScanQueue* q = new RefToScanQueue();
     q->initialize();
     _task_queues->register_queue(i, q);
   }
   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
     _gc_alloc_regions[ap]          = NULL;
     _gc_alloc_region_counts[ap]    = 0;
     _retained_gc_alloc_regions[ap] = NULL;
     // by default, we do not retain a GC alloc region for each ap;
     // we'll override this, when appropriate, below
     _retain_gc_alloc_region[ap]    = false;
   }
   // We will try to remember the last half-full tenured region we
   // allocated to at the end of a collection so that we can re-use it
   // during the next collection.
   _retain_gc_alloc_region[GCAllocForTenured]  = true;
   guarantee(_task_queues != NULL, "task_queues allocation failure.");
 }
 jint G1CollectedHeap::initialize() {
   CollectedHeap::pre_initialize();
   os::enable_vtime();
   // Necessary to satisfy locking discipline assertions.
   MutexLocker x(Heap_lock);
   // 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");
   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
   size_t max_byte_size = collector_policy()->max_heap_byte_size();
   // Ensure that the sizes are properly aligned.
   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
   _cg1r = new ConcurrentG1Refine();
   // Reserve the maximum.
   PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
   // Includes the perm-gen.
   const size_t total_reserved = max_byte_size + pgs->max_size();
   char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
   ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
                         HeapRegion::GrainBytes,
                         false /*ism*/, addr);
   if (UseCompressedOops) {
     if (addr != 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.
       addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
       ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
                              false /*ism*/, addr);
       if (addr != NULL && !heap_rs0.is_reserved()) {
         // Failed to reserve at specified address again - give up.
         addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
         assert(addr == NULL, "");
         ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
                                false /*ism*/, addr);
         heap_rs = heap_rs1;
       } else {
         heap_rs = heap_rs0;
       }
     }
   }
   if (!heap_rs.is_reserved()) {
     vm_exit_during_initialization("Could not reserve enough space for object heap");
     return JNI_ENOMEM;
   }
   // It is important to do this in a way such that concurrent readers can't
   // temporarily think somethings in the heap.  (I've actually seen this
   // happen in asserts: DLD.)
   _reserved.set_word_size(0);
   _reserved.set_start((HeapWord*)heap_rs.base());
   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
   _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
   _num_humongous_regions = 0;
   // Create the gen rem set (and barrier set) for the entire reserved region.
   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
   set_barrier_set(rem_set()->bs());
   if (barrier_set()->is_a(BarrierSet::ModRef)) {
     _mr_bs = (ModRefBarrierSet*)_barrier_set;
   } else {
     vm_exit_during_initialization("G1 requires a mod ref bs.");
     return JNI_ENOMEM;
   }
   // Also create a G1 rem set.
   if (G1UseHRIntoRS) {
     if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
       _g1_rem_set = new HRInto_G1RemSet(this, (CardTableModRefBS*)mr_bs());
     } else {
       vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
       return JNI_ENOMEM;
     }
   } else {
     _g1_rem_set = new StupidG1RemSet(this);
   }
   // Carve out the G1 part of the heap.
   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
                            g1_rs.size()/HeapWordSize);
   ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
   _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
   _g1_storage.initialize(g1_rs, 0);
   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
   _g1_max_committed = _g1_committed;
   _hrs = new HeapRegionSeq(_expansion_regions);
   guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
   guarantee(_cur_alloc_region == NULL, "from constructor");
   // 6843694 - ensure that the maximum region index can fit
   // in the remembered set structures.
   const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
   guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
             "too many cards per region");
   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
                                              heap_word_size(init_byte_size));
   _g1h = this;
    _in_cset_fast_test_length = max_regions();
    _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
    // We're biasing _in_cset_fast_test to avoid subtracting the
    // beginning of the heap every time we want to index; basically
    // it's the same with what we do with the card table.
    _in_cset_fast_test = _in_cset_fast_test_base -
                 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
    // Clear the _cset_fast_test bitmap in anticipation of adding
    // regions to the incremental collection set for the first
    // evacuation pause.
    clear_cset_fast_test();
   // Create the ConcurrentMark data structure and thread.
   // (Must do this late, so that "max_regions" is defined.)
   _cm       = new ConcurrentMark(heap_rs, (int) max_regions());
   _cmThread = _cm->cmThread();
   // ...and the concurrent zero-fill thread, if necessary.
   if (G1ConcZeroFill) {
     _czft = new ConcurrentZFThread();
   }
   // Initialize the from_card cache structure of HeapRegionRemSet.
   HeapRegionRemSet::init_heap(max_regions());
   // Now expand into the initial heap size.
   expand(init_byte_size);
   // Perform any initialization actions delegated to the policy.
   g1_policy()->init();
   g1_policy()->note_start_of_mark_thread();
   _refine_cte_cl =
     new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
                                     g1_rem_set(),
                                     concurrent_g1_refine());
   JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
                                                SATB_Q_FL_lock,
                                                G1SATBProcessCompletedThreshold,
                                                Shared_SATB_Q_lock);
   JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
                                                 DirtyCardQ_FL_lock,
                                                 concurrent_g1_refine()->yellow_zone(),
                                                 concurrent_g1_refine()->red_zone(),
                                                 Shared_DirtyCardQ_lock);
   if (G1DeferredRSUpdate) {
     dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
                                       DirtyCardQ_FL_lock,
                                       -1, // never trigger processing
                                       -1, // no limit on length
                                       Shared_DirtyCardQ_lock,
                                       &JavaThread::dirty_card_queue_set());
   }
   // Initialize the card queue set used to hold cards containing
   // references into the collection set.
   _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
                                              DirtyCardQ_FL_lock,
                                              -1, // never trigger processing
                                              -1, // no limit on length
                                              Shared_DirtyCardQ_lock,
                                              &JavaThread::dirty_card_queue_set());
   // In case we're keeping closure specialization stats, initialize those
   // counts and that mechanism.
   SpecializationStats::clear();
   _gc_alloc_region_list = NULL;
   // Do later initialization work for concurrent refinement.
   _cg1r->init();
   return JNI_OK;
 }
 void G1CollectedHeap::ref_processing_init() {
   SharedHeap::ref_processing_init();
   MemRegion mr = reserved_region();
   _ref_processor = ReferenceProcessor::create_ref_processor(
                                          mr,    // span
                                          false, // Reference discovery is not atomic
                                                 // (though it shouldn't matter here.)
                                          true,  // mt_discovery
                                          NULL,  // is alive closure: need to fill this in for efficiency
                                          ParallelGCThreads,
                                          ParallelRefProcEnabled,
                                          true); // Setting next fields of discovered
                                                 // lists requires a barrier.
 }
 size_t G1CollectedHeap::capacity() const {
   return _g1_committed.byte_size();
 }
 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
                                                  DirtyCardQueue* into_cset_dcq,
                                                  bool concurrent,
                                                  int worker_i) {
   // Clean cards in the hot card cache
   concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   int n_completed_buffers = 0;
   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
     n_completed_buffers++;
   }
   g1_policy()->record_update_rs_processed_buffers(worker_i,
                                                   (double) n_completed_buffers);
   dcqs.clear_n_completed_buffers();
   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
 }
 // Computes the sum of the storage used by the various regions.
 size_t G1CollectedHeap::used() const {
   assert(Heap_lock->owner() != NULL,
          "Should be owned on this thread's behalf.");
   size_t result = _summary_bytes_used;
   // Read only once in case it is set to NULL concurrently
   HeapRegion* hr = _cur_alloc_region;
   if (hr != NULL)
     result += hr->used();
   return result;
 }
 size_t G1CollectedHeap::used_unlocked() const {
   size_t result = _summary_bytes_used;
   return result;
 }
 class SumUsedClosure: public HeapRegionClosure {
   size_t _used;
 public:
   SumUsedClosure() : _used(0) {}
   bool doHeapRegion(HeapRegion* r) {
     if (!r->continuesHumongous()) {
       _used += r->used();
     }
     return false;
   }
   size_t result() { return _used; }
 };
 size_t G1CollectedHeap::recalculate_used() const {
   SumUsedClosure blk;
   _hrs->iterate(&blk);
   return blk.result();
 }
 #ifndef PRODUCT
 class SumUsedRegionsClosure: public HeapRegionClosure {
   size_t _num;
 public:
   SumUsedRegionsClosure() : _num(0) {}
   bool doHeapRegion(HeapRegion* r) {
     if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
       _num += 1;
     }
     return false;
   }
   size_t result() { return _num; }
 };
 size_t G1CollectedHeap::recalculate_used_regions() const {
   SumUsedRegionsClosure blk;
   _hrs->iterate(&blk);
   return blk.result();
 }
 #endif // PRODUCT
 size_t G1CollectedHeap::unsafe_max_alloc() {
   if (_free_regions > 0) return HeapRegion::GrainBytes;
   // otherwise, is there space in the current allocation region?
   // We need to store the current allocation region in a local variable
   // here. The problem is that this method doesn't take any locks and
   // there may be other threads which overwrite the current allocation
   // region field. attempt_allocation(), for example, sets it to NULL
   // and this can happen *after* the NULL check here but before the call
   // to free(), resulting in a SIGSEGV. Note that this doesn't appear
   // to be a problem in the optimized build, since the two loads of the
   // current allocation region field are optimized away.
   HeapRegion* car = _cur_alloc_region;
   // FIXME: should iterate over all regions?
   if (car == NULL) {
     return 0;
   }
   return car->free();
 }
 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
   return
     ((cause == GCCause::_gc_locker           && GCLockerInvokesConcurrent) ||
      (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
 }
 void G1CollectedHeap::increment_full_collections_completed(bool outer) {
   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
   // We have already incremented _total_full_collections at the start
   // of the GC, so total_full_collections() represents how many full
   // collections have been started.
   unsigned int full_collections_started = total_full_collections();
   // Given that this method is called at the end of a Full GC or of a
   // concurrent cycle, and those can be nested (i.e., a Full GC can
   // interrupt a concurrent cycle), the number of full collections
   // completed should be either one (in the case where there was no
   // nesting) or two (when a Full GC interrupted a concurrent cycle)
   // behind the number of full collections started.
   // This is the case for the inner caller, i.e. a Full GC.
   assert(outer ||
          (full_collections_started == _full_collections_completed + 1) ||
          (full_collections_started == _full_collections_completed + 2),
          err_msg("for inner caller: full_collections_started = %u "
                  "is inconsistent with _full_collections_completed = %u",
                  full_collections_started, _full_collections_completed));
   // This is the case for the outer caller, i.e. the concurrent cycle.
   assert(!outer ||
          (full_collections_started == _full_collections_completed + 1),
          err_msg("for outer caller: full_collections_started = %u "
                  "is inconsistent with _full_collections_completed = %u",
                  full_collections_started, _full_collections_completed));
   _full_collections_completed += 1;
   // This notify_all() will ensure that a thread that called
   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
   // and it's waiting for a full GC to finish will be woken up. It is
   // waiting in VM_G1IncCollectionPause::doit_epilogue().
   FullGCCount_lock->notify_all();
 }
 void G1CollectedHeap::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
       break;
     }
     default: // XXX FIX ME
       ShouldNotReachHere(); // Unexpected use of this function
   }
 }
 void G1CollectedHeap::collect(GCCause::Cause cause) {
   // The caller doesn't have the Heap_lock
   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
   unsigned int gc_count_before;
   unsigned int full_gc_count_before;
   {
     MutexLocker ml(Heap_lock);
     // Read the GC count while holding the Heap_lock
     gc_count_before = SharedHeap::heap()->total_collections();
     full_gc_count_before = SharedHeap::heap()->total_full_collections();
     // Don't want to do a GC until cleanup is completed.
     wait_for_cleanup_complete();
     // We give up heap lock; VMThread::execute gets it back below
   }
   if (should_do_concurrent_full_gc(cause)) {
     // Schedule an initial-mark evacuation pause that will start a
     // concurrent cycle.
     VM_G1IncCollectionPause op(gc_count_before,
                                true, /* should_initiate_conc_mark */
                                g1_policy()->max_pause_time_ms(),
                                cause);
     VMThread::execute(&op);
   } else {
     if (cause == GCCause::_gc_locker
         DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
       // Schedule a standard evacuation pause.
       VM_G1IncCollectionPause op(gc_count_before,
                                  false, /* should_initiate_conc_mark */
                                  g1_policy()->max_pause_time_ms(),
                                  cause);
       VMThread::execute(&op);
     } else {
       // Schedule a Full GC.
       VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
       VMThread::execute(&op);
     }
   }
 }
 bool G1CollectedHeap::is_in(const void* p) const {
   if (_g1_committed.contains(p)) {
     HeapRegion* hr = _hrs->addr_to_region(p);
     return hr->is_in(p);
   } else {
     return _perm_gen->as_gen()->is_in(p);
   }
 }
 // Iteration functions.
 // Iterates an OopClosure over all ref-containing fields of objects
 // within a HeapRegion.
 class IterateOopClosureRegionClosure: public HeapRegionClosure {
   MemRegion _mr;
   OopClosure* _cl;
 public:
   IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
     : _mr(mr), _cl(cl) {}
   bool doHeapRegion(HeapRegion* r) {
     if (! r->continuesHumongous()) {
       r->oop_iterate(_cl);
     }
     return false;
   }
 };
 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
   IterateOopClosureRegionClosure blk(_g1_committed, cl);
   _hrs->iterate(&blk);
   if (do_perm) {
     perm_gen()->oop_iterate(cl);
   }
 }
 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
   IterateOopClosureRegionClosure blk(mr, cl);
   _hrs->iterate(&blk);
   if (do_perm) {
     perm_gen()->oop_iterate(cl);
   }
 }
 // Iterates an ObjectClosure over all objects within a HeapRegion.
 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
   ObjectClosure* _cl;
 public:
   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
   bool doHeapRegion(HeapRegion* r) {
     if (! r->continuesHumongous()) {
       r->object_iterate(_cl);
     }
     return false;
   }
 };
 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
   IterateObjectClosureRegionClosure blk(cl);
   _hrs->iterate(&blk);
   if (do_perm) {
     perm_gen()->object_iterate(cl);
   }
 }
 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
   // FIXME: is this right?
   guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
 }
 // Calls a SpaceClosure on a HeapRegion.
 class SpaceClosureRegionClosure: public HeapRegionClosure {
   SpaceClosure* _cl;
 public:
   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
   bool doHeapRegion(HeapRegion* r) {
     _cl->do_space(r);
     return false;
   }
 };
 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
   SpaceClosureRegionClosure blk(cl);
   _hrs->iterate(&blk);
 }
 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
   _hrs->iterate(cl);
 }
 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
                                                HeapRegionClosure* cl) {
   _hrs->iterate_from(r, cl);
 }
 void
 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
   _hrs->iterate_from(idx, cl);
 }
 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
 void
 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
                                                  int worker,
                                                  jint claim_value) {
   const size_t regions = n_regions();
   const size_t worker_num = (ParallelGCThreads > 0 ? ParallelGCThreads : 1);
   // try to spread out the starting points of the workers
   const size_t start_index = regions / worker_num * (size_t) worker;
   // each worker will actually look at all regions
   for (size_t count = 0; count < regions; ++count) {
     const size_t index = (start_index + count) % regions;
     assert(0 <= index && index < regions, "sanity");
     HeapRegion* r = region_at(index);
     // we'll ignore "continues humongous" regions (we'll process them
     // when we come across their corresponding "start humongous"
     // region) and regions already claimed
     if (r->claim_value() == claim_value || r->continuesHumongous()) {
       continue;
     }
     // OK, try to claim it
     if (r->claimHeapRegion(claim_value)) {
       // success!
       assert(!r->continuesHumongous(), "sanity");
       if (r->startsHumongous()) {
         // If the region is "starts humongous" we'll iterate over its
         // "continues humongous" first; in fact we'll do them
         // first. The order is important. In on case, calling the
         // closure on the "starts humongous" region might de-allocate
         // and clear all its "continues humongous" regions and, as a
         // result, we might end up processing them twice. So, we'll do
         // them first (notice: most closures will ignore them anyway) and
         // then we'll do the "starts humongous" region.
         for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
           HeapRegion* chr = region_at(ch_index);
           // if the region has already been claimed or it's not
           // "continues humongous" we're done
           if (chr->claim_value() == claim_value ||
               !chr->continuesHumongous()) {
             break;
           }
           // Noone should have claimed it directly. We can given
           // that we claimed its "starts humongous" region.
           assert(chr->claim_value() != claim_value, "sanity");
           assert(chr->humongous_start_region() == r, "sanity");
           if (chr->claimHeapRegion(claim_value)) {
             // we should always be able to claim it; noone else should
             // be trying to claim this region
             bool res2 = cl->doHeapRegion(chr);
             assert(!res2, "Should not abort");
             // Right now, this holds (i.e., no closure that actually
             // does something with "continues humongous" regions
             // clears them). We might have to weaken it in the future,
             // but let's leave these two asserts here for extra safety.
             assert(chr->continuesHumongous(), "should still be the case");
             assert(chr->humongous_start_region() == r, "sanity");
           } else {
             guarantee(false, "we should not reach here");
           }
         }
       }
       assert(!r->continuesHumongous(), "sanity");
       bool res = cl->doHeapRegion(r);
       assert(!res, "Should not abort");
     }
   }
 }
 class ResetClaimValuesClosure: public HeapRegionClosure {
 public:
   bool doHeapRegion(HeapRegion* r) {
     r->set_claim_value(HeapRegion::InitialClaimValue);
     return false;
   }
 };
 void
 G1CollectedHeap::reset_heap_region_claim_values() {
   ResetClaimValuesClosure blk;
   heap_region_iterate(&blk);
 }
 #ifdef ASSERT
 // This checks whether all regions in the heap have the correct claim
 // value. I also piggy-backed on this a check to ensure that the
 // humongous_start_region() information on "continues humongous"
 // regions is correct.
 class CheckClaimValuesClosure : public HeapRegionClosure {
 private:
   jint _claim_value;
   size_t _failures;
   HeapRegion* _sh_region;
 public:
   CheckClaimValuesClosure(jint claim_value) :
     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
   bool doHeapRegion(HeapRegion* r) {
     if (r->claim_value() != _claim_value) {
       gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
                              "claim value = %d, should be %d",
                              r->bottom(), r->end(), r->claim_value(),
                              _claim_value);
       ++_failures;
     }
     if (!r->isHumongous()) {
       _sh_region = NULL;
     } else if (r->startsHumongous()) {
       _sh_region = r;
     } else if (r->continuesHumongous()) {
       if (r->humongous_start_region() != _sh_region) {
         gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
                                r->bottom(), r->end(),
                                r->humongous_start_region(),
                                _sh_region);
         ++_failures;
       }
     }
     return false;
   }
   size_t failures() {
     return _failures;
   }
 };
 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
   CheckClaimValuesClosure cl(claim_value);
   heap_region_iterate(&cl);
   return cl.failures() == 0;
 }
 #endif // ASSERT
 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
   HeapRegion* r = g1_policy()->collection_set();
   while (r != NULL) {
     HeapRegion* next = r->next_in_collection_set();
     if (cl->doHeapRegion(r)) {
       cl->incomplete();
       return;
     }
     r = next;
   }
 }
 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
                                                   HeapRegionClosure *cl) {
   if (r == NULL) {
     // The CSet is empty so there's nothing to do.
     return;
   }
   assert(r->in_collection_set(),
          "Start region must be a member of the collection set.");
   HeapRegion* cur = r;
   while (cur != NULL) {
     HeapRegion* next = cur->next_in_collection_set();
     if (cl->doHeapRegion(cur) && false) {
       cl->incomplete();
       return;
     }
     cur = next;
   }
   cur = g1_policy()->collection_set();
   while (cur != r) {
     HeapRegion* next = cur->next_in_collection_set();
     if (cl->doHeapRegion(cur) && false) {
       cl->incomplete();
       return;
     }
     cur = next;
   }
 }
 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
   return _hrs->length() > 0 ? _hrs->at(0) : NULL;
 }
 Space* G1CollectedHeap::space_containing(const void* addr) const {
   Space* res = heap_region_containing(addr);
   if (res == NULL)
     res = perm_gen()->space_containing(addr);
   return res;
 }
 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
   Space* sp = space_containing(addr);
   if (sp != NULL) {
     return sp->block_start(addr);
   }
   return NULL;
 }
 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
   Space* sp = space_containing(addr);
   assert(sp != NULL, "block_size of address outside of heap");
   return sp->block_size(addr);
 }
 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
   Space* sp = space_containing(addr);
   return sp->block_is_obj(addr);
 }
 bool G1CollectedHeap::supports_tlab_allocation() const {
   return true;
 }
 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
   return HeapRegion::GrainBytes;
 }
 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
   // Return the remaining space in the cur alloc region, but not less than
   // the min TLAB size.
   // Also, this value can be at most the humongous object threshold,
   // since we can't allow tlabs to grow big enough to accomodate
   // humongous objects.
   // We need to store the cur alloc region locally, since it might change
   // between when we test for NULL and when we use it later.
   ContiguousSpace* cur_alloc_space = _cur_alloc_region;
   size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
   if (cur_alloc_space == NULL) {
     return max_tlab_size;
   } else {
     return MIN2(MAX2(cur_alloc_space->free(), (size_t)MinTLABSize),
                 max_tlab_size);
   }
 }
 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
   bool dummy;
   return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
 }
 bool G1CollectedHeap::allocs_are_zero_filled() {
   return false;
 }
 size_t G1CollectedHeap::large_typearray_limit() {
   // FIXME
   return HeapRegion::GrainBytes/HeapWordSize;
 }
 size_t G1CollectedHeap::max_capacity() const {
   return g1_reserved_obj_bytes();
 }
 jlong G1CollectedHeap::millis_since_last_gc() {
   // assert(false, "NYI");
   return 0;
 }
 void G1CollectedHeap::prepare_for_verify() {
   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
     ensure_parsability(false);
   }
   g1_rem_set()->prepare_for_verify();
 }
 class VerifyLivenessOopClosure: public OopClosure {
   G1CollectedHeap* g1h;
 public:
   VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
     g1h = _g1h;
   }
   void do_oop(narrowOop *p) { do_oop_work(p); }
   void do_oop(      oop *p) { do_oop_work(p); }
   template <class T> void do_oop_work(T *p) {
     oop obj = oopDesc::load_decode_heap_oop(p);
     guarantee(obj == NULL || !g1h->is_obj_dead(obj),
               "Dead object referenced by a not dead object");
   }
 };
 class VerifyObjsInRegionClosure: public ObjectClosure {
 private:
   G1CollectedHeap* _g1h;
   size_t _live_bytes;
   HeapRegion *_hr;
   bool _use_prev_marking;
 public:
   // use_prev_marking == true  -> use "prev" marking information,
   // use_prev_marking == false -> use "next" marking information
   VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
     : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
     _g1h = G1CollectedHeap::heap();
   }
   void do_object(oop o) {
     VerifyLivenessOopClosure isLive(_g1h);
     assert(o != NULL, "Huh?");
     if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
       o->oop_iterate(&isLive);
       if (!_hr->obj_allocated_since_prev_marking(o)) {
         size_t obj_size = o->size();    // Make sure we don't overflow
         _live_bytes += (obj_size * HeapWordSize);
       }
     }
   }
   size_t live_bytes() { return _live_bytes; }
 };
 class PrintObjsInRegionClosure : public ObjectClosure {
   HeapRegion *_hr;
   G1CollectedHeap *_g1;
 public:
   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
     _g1 = G1CollectedHeap::heap();
   };
   void do_object(oop o) {
     if (o != NULL) {
       HeapWord *start = (HeapWord *) o;
       size_t word_sz = o->size();
       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
                           (void*) o, word_sz,
                           _g1->isMarkedPrev(o),
                           _g1->isMarkedNext(o),
                           _hr->obj_allocated_since_prev_marking(o));
       HeapWord *end = start + word_sz;
       HeapWord *cur;
       int *val;
       for (cur = start; cur < end; cur++) {
         val = (int *) cur;
         gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
       }
     }
   }
 };
 class VerifyRegionClosure: public HeapRegionClosure {
 private:
   bool _allow_dirty;
   bool _par;
   bool _use_prev_marking;
   bool _failures;
 public:
   // use_prev_marking == true  -> use "prev" marking information,
   // use_prev_marking == false -> use "next" marking information
   VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
     : _allow_dirty(allow_dirty),
       _par(par),
       _use_prev_marking(use_prev_marking),
       _failures(false) {}
   bool failures() {
     return _failures;
   }
   bool doHeapRegion(HeapRegion* r) {
     guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
               "Should be unclaimed at verify points.");
     if (!r->continuesHumongous()) {
       bool failures = false;
       r->verify(_allow_dirty, _use_prev_marking, &failures);
       if (failures) {
         _failures = true;
       } else {
         VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
         r->object_iterate(&not_dead_yet_cl);
         if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
           gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
                                  "max_live_bytes "SIZE_FORMAT" "
                                  "< calculated "SIZE_FORMAT,
                                  r->bottom(), r->end(),
                                  r->max_live_bytes(),
                                  not_dead_yet_cl.live_bytes());
           _failures = true;
         }
       }
     }
     return false; // stop the region iteration if we hit a failure
   }
 };
 class VerifyRootsClosure: public OopsInGenClosure {
 private:
   G1CollectedHeap* _g1h;
   bool             _use_prev_marking;
   bool             _failures;
 public:
   // use_prev_marking == true  -> use "prev" marking information,
   // use_prev_marking == false -> use "next" marking information
   VerifyRootsClosure(bool use_prev_marking) :
     _g1h(G1CollectedHeap::heap()),
     _use_prev_marking(use_prev_marking),
     _failures(false) { }
   bool failures() { return _failures; }
   template <class T> void do_oop_nv(T* p) {
     T heap_oop = oopDesc::load_heap_oop(p);
     if (!oopDesc::is_null(heap_oop)) {
       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
       if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
         obj->print_on(gclog_or_tty);
         _failures = true;
       }
     }
   }
   void do_oop(oop* p)       { do_oop_nv(p); }
   void do_oop(narrowOop* p) { do_oop_nv(p); }
 };
 // This is the task used for parallel heap verification.
 class G1ParVerifyTask: public AbstractGangTask {
 private:
   G1CollectedHeap* _g1h;
   bool _allow_dirty;
   bool _use_prev_marking;
   bool _failures;
 public:
   // use_prev_marking == true  -> use "prev" marking information,
   // use_prev_marking == false -> use "next" marking information
   G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
                   bool use_prev_marking) :
     AbstractGangTask("Parallel verify task"),
     _g1h(g1h),
     _allow_dirty(allow_dirty),
     _use_prev_marking(use_prev_marking),
     _failures(false) { }
   bool failures() {
     return _failures;
   }
   void work(int worker_i) {
     HandleMark hm;
     VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
     _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
                                           HeapRegion::ParVerifyClaimValue);
     if (blk.failures()) {
       _failures = true;
     }
   }
 };
 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
   verify(allow_dirty, silent, /* use_prev_marking */ true);
 }
 void G1CollectedHeap::verify(bool allow_dirty,
                              bool silent,
                              bool use_prev_marking) {
   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
     if (!silent) { gclog_or_tty->print("roots "); }
     VerifyRootsClosure rootsCl(use_prev_marking);
     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
     process_strong_roots(true,  // activate StrongRootsScope
                          false,
                          SharedHeap::SO_AllClasses,
                          &rootsCl,
                          &blobsCl,
                          &rootsCl);
     bool failures = rootsCl.failures();
     rem_set()->invalidate(perm_gen()->used_region(), false);
     if (!silent) { gclog_or_tty->print("heapRegions "); }
     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
              "sanity check");
       G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
       int n_workers = workers()->total_workers();
       set_par_threads(n_workers);
       workers()->run_task(&task);
       set_par_threads(0);
       if (task.failures()) {
         failures = true;
       }
       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
              "sanity check");
       reset_heap_region_claim_values();
       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
              "sanity check");
     } else {
       VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
       _hrs->iterate(&blk);
       if (blk.failures()) {
         failures = true;
       }
     }
     if (!silent) gclog_or_tty->print("remset ");
     rem_set()->verify();
     if (failures) {
       gclog_or_tty->print_cr("Heap:");
       print_on(gclog_or_tty, true /* extended */);
       gclog_or_tty->print_cr("");
 #ifndef PRODUCT
       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
         concurrent_mark()->print_reachable("at-verification-failure",
                                            use_prev_marking, false /* all */);
       }
 #endif
       gclog_or_tty->flush();
     }
     guarantee(!failures, "there should not have been any failures");
   } else {
     if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
   }
 }
 class PrintRegionClosure: public HeapRegionClosure {
   outputStream* _st;
 public:
   PrintRegionClosure(outputStream* st) : _st(st) {}
   bool doHeapRegion(HeapRegion* r) {
     r->print_on(_st);
     return false;
   }
 };
 void G1CollectedHeap::print() const { print_on(tty); }
 void G1CollectedHeap::print_on(outputStream* st) const {
   print_on(st, PrintHeapAtGCExtended);
 }
 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
   st->print(" %-20s", "garbage-first heap");
   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
             capacity()/K, used_unlocked()/K);
   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
             _g1_storage.low_boundary(),
             _g1_storage.high(),
             _g1_storage.high_boundary());
   st->cr();
   st->print("  region size " SIZE_FORMAT "K, ",
             HeapRegion::GrainBytes/K);
   size_t young_regions = _young_list->length();
   st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
             young_regions, young_regions * HeapRegion::GrainBytes / K);
   size_t survivor_regions = g1_policy()->recorded_survivor_regions();
   st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
             survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
   st->cr();
   perm()->as_gen()->print_on(st);
   if (extended) {
     st->cr();
     print_on_extended(st);
   }
 }
 void G1CollectedHeap::print_on_extended(outputStream* st) const {
   PrintRegionClosure blk(st);
   _hrs->iterate(&blk);
 }
 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
   if (ParallelGCThreads > 0) {
     workers()->print_worker_threads_on(st);
   }
   _cmThread->print_on(st);
   st->cr();
   _cm->print_worker_threads_on(st);
   _cg1r->print_worker_threads_on(st);
   _czft->print_on(st);
   st->cr();
 }
 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
   if (ParallelGCThreads > 0) {
     workers()->threads_do(tc);
   }
   tc->do_thread(_cmThread);
   _cg1r->threads_do(tc);
   tc->do_thread(_czft);
 }
 void G1CollectedHeap::print_tracing_info() const {
   // We'll overload this to mean "trace GC pause statistics."
   if (TraceGen0Time || TraceGen1Time) {
     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
     // to that.
     g1_policy()->print_tracing_info();
   }
   if (G1SummarizeRSetStats) {
     g1_rem_set()->print_summary_info();
   }
   if (G1SummarizeConcMark) {
     concurrent_mark()->print_summary_info();
   }
   if (G1SummarizeZFStats) {
     ConcurrentZFThread::print_summary_info();
   }
   g1_policy()->print_yg_surv_rate_info();
   SpecializationStats::print();
 }
 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
   HeapRegion* hr = heap_region_containing(addr);
   if (hr == NULL) {
     return 0;
   } else {
     return 1;
   }
 }
 G1CollectedHeap* G1CollectedHeap::heap() {
   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
          "not a garbage-first heap");
   return _g1h;
 }
 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
   // always_do_update_barrier = false;
   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
   // Call allocation profiler
   AllocationProfiler::iterate_since_last_gc();
   // Fill TLAB's and such
   ensure_parsability(true);
 }
 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
   // FIXME: what is this about?
   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
   // is set.
   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
                         "derived pointer present"));
   // always_do_update_barrier = true;
 }
 void G1CollectedHeap::do_collection_pause() {
   assert(Heap_lock->owned_by_self(), "we assume we'reholding the Heap_lock");
   // Read the GC count while holding the Heap_lock
   // we need to do this _before_ wait_for_cleanup_complete(), to
   // ensure that we do not give up the heap lock and potentially
   // pick up the wrong count
   unsigned int gc_count_before = SharedHeap::heap()->total_collections();
   // Don't want to do a GC pause while cleanup is being completed!
   wait_for_cleanup_complete();
   g1_policy()->record_stop_world_start();
   {
     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
     VM_G1IncCollectionPause op(gc_count_before,
                                false, /* should_initiate_conc_mark */
                                g1_policy()->max_pause_time_ms(),
                                GCCause::_g1_inc_collection_pause);
     VMThread::execute(&op);
   }
 }
 void
 G1CollectedHeap::doConcurrentMark() {
   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
   if (!_cmThread->in_progress()) {
     _cmThread->set_started();
     CGC_lock->notify();
   }
 }
 class VerifyMarkedObjsClosure: public ObjectClosure {
     G1CollectedHeap* _g1h;
     public:
     VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
     void do_object(oop obj) {
       assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
              "markandsweep mark should agree with concurrent deadness");
     }
 };
 void
 G1CollectedHeap::checkConcurrentMark() {
     VerifyMarkedObjsClosure verifycl(this);
     //    MutexLockerEx x(getMarkBitMapLock(),
     //              Mutex::_no_safepoint_check_flag);
     object_iterate(&verifycl, false);
 }
 void G1CollectedHeap::do_sync_mark() {
   _cm->checkpointRootsInitial();
   _cm->markFromRoots();
   _cm->checkpointRootsFinal(false);
 }
 // <NEW PREDICTION>
 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
                                                        bool young) {
   return _g1_policy->predict_region_elapsed_time_ms(hr, young);
 }
 void G1CollectedHeap::check_if_region_is_too_expensive(double
                                                            predicted_time_ms) {
   _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
 }
 size_t G1CollectedHeap::pending_card_num() {
   size_t extra_cards = 0;
   JavaThread *curr = Threads::first();
   while (curr != NULL) {
     DirtyCardQueue& dcq = curr->dirty_card_queue();
     extra_cards += dcq.size();
     curr = curr->next();
   }
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   size_t buffer_size = dcqs.buffer_size();
   size_t buffer_num = dcqs.completed_buffers_num();
   return buffer_size * buffer_num + extra_cards;
 }
 size_t G1CollectedHeap::max_pending_card_num() {
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   size_t buffer_size = dcqs.buffer_size();
   size_t buffer_num  = dcqs.completed_buffers_num();
   int thread_num  = Threads::number_of_threads();
   return (buffer_num + thread_num) * buffer_size;
 }
 size_t G1CollectedHeap::cards_scanned() {
   HRInto_G1RemSet* g1_rset = (HRInto_G1RemSet*) g1_rem_set();
   return g1_rset->cardsScanned();
 }
 void
 G1CollectedHeap::setup_surviving_young_words() {
   guarantee( _surviving_young_words == NULL, "pre-condition" );
   size_t array_length = g1_policy()->young_cset_length();
   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
   if (_surviving_young_words == NULL) {
     vm_exit_out_of_memory(sizeof(size_t) * array_length,
                           "Not enough space for young surv words summary.");
   }
   memset(_surviving_young_words, 0, array_length * sizeof(size_t));
 #ifdef ASSERT
   for (size_t i = 0;  i < array_length; ++i) {
     assert( _surviving_young_words[i] == 0, "memset above" );
   }
 #endif // !ASSERT
 }
 void
 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
   size_t array_length = g1_policy()->young_cset_length();
   for (size_t i = 0; i < array_length; ++i)
     _surviving_young_words[i] += surv_young_words[i];
 }
 void
 G1CollectedHeap::cleanup_surviving_young_words() {
   guarantee( _surviving_young_words != NULL, "pre-condition" );
   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
   _surviving_young_words = NULL;
 }
 // </NEW PREDICTION>
 struct PrepareForRSScanningClosure : public HeapRegionClosure {
   bool doHeapRegion(HeapRegion *r) {
     r->rem_set()->set_iter_claimed(0);
     return false;
   }
 };
 #if TASKQUEUE_STATS
 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
   st->print_raw_cr("GC Task Stats");
   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
 }
 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
   print_taskqueue_stats_hdr(st);
   TaskQueueStats totals;
   const int n = MAX2(workers()->total_workers(), 1);
   for (int i = 0; i < n; ++i) {
     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
     totals += task_queue(i)->stats;
   }
   st->print_raw("tot "); totals.print(st); st->cr();
   DEBUG_ONLY(totals.verify());
 }
 void G1CollectedHeap::reset_taskqueue_stats() {
   const int n = MAX2(workers()->total_workers(), 1);
   for (int i = 0; i < n; ++i) {
     task_queue(i)->stats.reset();
   }
 }
 #endif // TASKQUEUE_STATS
 void
 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
   if (GC_locker::check_active_before_gc()) {
     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
   }
   if (PrintHeapAtGC) {
     Universe::print_heap_before_gc();
   }
   {
     ResourceMark rm;
     // This call will decide whether this pause is an initial-mark
     // pause. If it is, during_initial_mark_pause() will return true
     // for the duration of this pause.
     g1_policy()->decide_on_conc_mark_initiation();
     char verbose_str[128];
     sprintf(verbose_str, "GC pause ");
     if (g1_policy()->in_young_gc_mode()) {
       if (g1_policy()->full_young_gcs())
         strcat(verbose_str, "(young)");
       else
         strcat(verbose_str, "(partial)");
     }
     if (g1_policy()->during_initial_mark_pause()) {
       strcat(verbose_str, " (initial-mark)");
       // We are about to start a marking cycle, so we increment the
       // full collection counter.
       increment_total_full_collections();
     }
     // if PrintGCDetails is on, we'll print long statistics information
     // in the collector policy code, so let's not print this as the output
     // is messy if we do.
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
     TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
     TraceMemoryManagerStats tms(false /* fullGC */);
     assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
     assert(Thread::current() == VMThread::vm_thread(), "should be in vm thread");
     guarantee(!is_gc_active(), "collection is not reentrant");
     assert(regions_accounted_for(), "Region leakage!");
     increment_gc_time_stamp();
     if (g1_policy()->in_young_gc_mode()) {
       assert(check_young_list_well_formed(),
              "young list should be well formed");
     }
     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
       IsGCActiveMark x;
       gc_prologue(false);
       increment_total_collections(false /* full gc */);
 #if G1_REM_SET_LOGGING
       gclog_or_tty->print_cr("\nJust chose CS, heap:");
       print();
 #endif
       if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
         HandleMark hm;  // Discard invalid handles created during verification
         prepare_for_verify();
         gclog_or_tty->print(" VerifyBeforeGC:");
         Universe::verify(false);
       }
       COMPILER2_PRESENT(DerivedPointerTable::clear());
       // We want to turn off ref discovery, if necessary, and turn it back on
       // on again later if we do. XXX Dubious: why is discovery disabled?
       bool was_enabled = ref_processor()->discovery_enabled();
       if (was_enabled) ref_processor()->disable_discovery();
       // Forget the current alloc region (we might even choose it to be part
       // of the collection set!).
       abandon_cur_alloc_region();
       // The elapsed time induced by the start time below deliberately elides
       // the possible verification above.
       double start_time_sec = os::elapsedTime();
       size_t start_used_bytes = used();
 #if YOUNG_LIST_VERBOSE
       gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
       _young_list->print();
       g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
 #endif // YOUNG_LIST_VERBOSE
       g1_policy()->record_collection_pause_start(start_time_sec,
                                                  start_used_bytes);
 #if YOUNG_LIST_VERBOSE
       gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
       _young_list->print();
 #endif // YOUNG_LIST_VERBOSE
       if (g1_policy()->during_initial_mark_pause()) {
         concurrent_mark()->checkpointRootsInitialPre();
       }
       save_marks();
       // We must do this before any possible evacuation that should propagate
       // marks.
       if (mark_in_progress()) {
         double start_time_sec = os::elapsedTime();
         _cm->drainAllSATBBuffers();
         double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
         g1_policy()->record_satb_drain_time(finish_mark_ms);
       }
       // Record the number of elements currently on the mark stack, so we
       // only iterate over these.  (Since evacuation may add to the mark
       // stack, doing more exposes race conditions.)  If no mark is in
       // progress, this will be zero.
       _cm->set_oops_do_bound();
       assert(regions_accounted_for(), "Region leakage.");
       if (mark_in_progress())
         concurrent_mark()->newCSet();
 #if YOUNG_LIST_VERBOSE
       gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
       _young_list->print();
       g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
 #endif // YOUNG_LIST_VERBOSE
       g1_policy()->choose_collection_set(target_pause_time_ms);
       // Nothing to do if we were unable to choose a collection set.
 #if G1_REM_SET_LOGGING
       gclog_or_tty->print_cr("\nAfter pause, heap:");
       print();
 #endif
       PrepareForRSScanningClosure prepare_for_rs_scan;
       collection_set_iterate(&prepare_for_rs_scan);
       setup_surviving_young_words();
       // Set up the gc allocation regions.
       get_gc_alloc_regions();
       // Actually do the work...
       evacuate_collection_set();
       free_collection_set(g1_policy()->collection_set());
       g1_policy()->clear_collection_set();
       cleanup_surviving_young_words();
       // Start a new incremental collection set for the next pause.
       g1_policy()->start_incremental_cset_building();
       // Clear the _cset_fast_test bitmap in anticipation of adding
       // regions to the incremental collection set for the next
       // evacuation pause.
       clear_cset_fast_test();
       if (g1_policy()->in_young_gc_mode()) {
         _young_list->reset_sampled_info();
         // Don't check the whole heap at this point as the
         // GC alloc regions from this pause have been tagged
         // as survivors and moved on to the survivor list.
         // Survivor regions will fail the !is_young() check.
         assert(check_young_list_empty(false /* check_heap */),
                "young list should be empty");
 #if YOUNG_LIST_VERBOSE
         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
         _young_list->print();
 #endif // YOUNG_LIST_VERBOSE
         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
                                           _young_list->first_survivor_region(),
                                           _young_list->last_survivor_region());
         _young_list->reset_auxilary_lists();
       }
       if (evacuation_failed()) {
         _summary_bytes_used = recalculate_used();
       } else {
         // The "used" of the the collection set have already been subtracted
         // when they were freed.  Add in the bytes evacuated.
         _summary_bytes_used += g1_policy()->bytes_in_to_space();
       }
       if (g1_policy()->in_young_gc_mode() &&
           g1_policy()->during_initial_mark_pause()) {
         concurrent_mark()->checkpointRootsInitialPost();
         set_marking_started();
         // CAUTION: after the doConcurrentMark() call below,
         // the concurrent marking thread(s) could be running
         // concurrently with us. Make sure that anything after
         // this point does not assume that we are the only GC thread
         // running. Note: of course, the actual marking work will
         // not start until the safepoint itself is released in
         // ConcurrentGCThread::safepoint_desynchronize().
         doConcurrentMark();
       }
 #if YOUNG_LIST_VERBOSE
       gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
       _young_list->print();
       g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
 #endif // YOUNG_LIST_VERBOSE
       double end_time_sec = os::elapsedTime();
       double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
       g1_policy()->record_pause_time_ms(pause_time_ms);
       g1_policy()->record_collection_pause_end();
       assert(regions_accounted_for(), "Region leakage.");
       MemoryService::track_memory_usage();
       if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
         HandleMark hm;  // Discard invalid handles created during verification
         gclog_or_tty->print(" VerifyAfterGC:");
         prepare_for_verify();
         Universe::verify(false);
       }
       if (was_enabled) ref_processor()->enable_discovery();
       {
         size_t expand_bytes = g1_policy()->expansion_amount();
         if (expand_bytes > 0) {
           size_t bytes_before = capacity();
           expand(expand_bytes);
         }
       }
       if (mark_in_progress()) {
         concurrent_mark()->update_g1_committed();
       }
 #ifdef TRACESPINNING
       ParallelTaskTerminator::print_termination_counts();
 #endif
       gc_epilogue(false);
     }
     assert(verify_region_lists(), "Bad region lists.");
     if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
       gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
       print_tracing_info();
       vm_exit(-1);
     }
   }
   TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
   TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
   if (PrintHeapAtGC) {
     Universe::print_heap_after_gc();
   }
   if (G1SummarizeRSetStats &&
       (G1SummarizeRSetStatsPeriod > 0) &&
       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
     g1_rem_set()->print_summary_info();
   }
 }
 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
 {
   size_t gclab_word_size;
   switch (purpose) {
     case GCAllocForSurvived:
       gclab_word_size = YoungPLABSize;
       break;
     case GCAllocForTenured:
       gclab_word_size = OldPLABSize;
       break;
     default:
       assert(false, "unknown GCAllocPurpose");
       gclab_word_size = OldPLABSize;
       break;
   }
   return gclab_word_size;
 }
 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
   assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
   // make sure we don't call set_gc_alloc_region() multiple times on
   // the same region
   assert(r == NULL || !r->is_gc_alloc_region(),
          "shouldn't already be a GC alloc region");
   assert(r == NULL || !r->isHumongous(),
          "humongous regions shouldn't be used as GC alloc regions");
   HeapWord* original_top = NULL;
   if (r != NULL)
     original_top = r->top();
   // We will want to record the used space in r as being there before gc.
   // One we install it as a GC alloc region it's eligible for allocation.
   // So record it now and use it later.
   size_t r_used = 0;
   if (r != NULL) {
     r_used = r->used();
     if (ParallelGCThreads > 0) {
       // need to take the lock to guard against two threads calling
       // get_gc_alloc_region concurrently (very unlikely but...)
       MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
       r->save_marks();
     }
   }
   HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
   _gc_alloc_regions[purpose] = r;
   if (old_alloc_region != NULL) {
     // Replace aliases too.
     for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
       if (_gc_alloc_regions[ap] == old_alloc_region) {
         _gc_alloc_regions[ap] = r;
       }
     }
   }
   if (r != NULL) {
     push_gc_alloc_region(r);
     if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
       // We are using a region as a GC alloc region after it has been used
       // as a mutator allocation region during the current marking cycle.
       // The mutator-allocated objects are currently implicitly marked, but
       // when we move hr->next_top_at_mark_start() forward at the the end
       // of the GC pause, they won't be.  We therefore mark all objects in
       // the "gap".  We do this object-by-object, since marking densely
       // does not currently work right with marking bitmap iteration.  This
       // means we rely on TLAB filling at the start of pauses, and no
       // "resuscitation" of filled TLAB's.  If we want to do this, we need
       // to fix the marking bitmap iteration.
       HeapWord* curhw = r->next_top_at_mark_start();
       HeapWord* t = original_top;
       while (curhw < t) {
         oop cur = (oop)curhw;
         // We'll assume parallel for generality.  This is rare code.
         concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
         curhw = curhw + cur->size();
       }
       assert(curhw == t, "Should have parsed correctly.");
     }
     if (G1PolicyVerbose > 1) {
       gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
                           "for survivors:", r->bottom(), original_top, r->end());
       r->print();
     }
     g1_policy()->record_before_bytes(r_used);
   }
 }
 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
   assert(Thread::current()->is_VM_thread() ||
          par_alloc_during_gc_lock()->owned_by_self(), "Precondition");
   assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
          "Precondition.");
   hr->set_is_gc_alloc_region(true);
   hr->set_next_gc_alloc_region(_gc_alloc_region_list);
   _gc_alloc_region_list = hr;
 }
 #ifdef G1_DEBUG
 class FindGCAllocRegion: public HeapRegionClosure {
 public:
   bool doHeapRegion(HeapRegion* r) {
     if (r->is_gc_alloc_region()) {
       gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
                              r->hrs_index(), r->bottom());
     }
     return false;
   }
 };
 #endif // G1_DEBUG
 void G1CollectedHeap::forget_alloc_region_list() {
   assert(Thread::current()->is_VM_thread(), "Precondition");
   while (_gc_alloc_region_list != NULL) {
     HeapRegion* r = _gc_alloc_region_list;
     assert(r->is_gc_alloc_region(), "Invariant.");
     // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
     // newly allocated data in order to be able to apply deferred updates
     // before the GC is done for verification purposes (i.e to allow
     // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
     // collection.
     r->ContiguousSpace::set_saved_mark();
     _gc_alloc_region_list = r->next_gc_alloc_region();
     r->set_next_gc_alloc_region(NULL);
     r->set_is_gc_alloc_region(false);
     if (r->is_survivor()) {
       if (r->is_empty()) {
         r->set_not_young();
       } else {
         _young_list->add_survivor_region(r);
       }
     }
     if (r->is_empty()) {
       ++_free_regions;
     }
   }
 #ifdef G1_DEBUG
   FindGCAllocRegion fa;
   heap_region_iterate(&fa);
 #endif // G1_DEBUG
 }
 bool G1CollectedHeap::check_gc_alloc_regions() {
   // TODO: allocation regions check
   return true;
 }
 void G1CollectedHeap::get_gc_alloc_regions() {
   // First, let's check that the GC alloc region list is empty (it should)
   assert(_gc_alloc_region_list == NULL, "invariant");
   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
     assert(_gc_alloc_regions[ap] == NULL, "invariant");
     assert(_gc_alloc_region_counts[ap] == 0, "invariant");
     // Create new GC alloc regions.
     HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
     _retained_gc_alloc_regions[ap] = NULL;
     if (alloc_region != NULL) {
       assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
       // let's make sure that the GC alloc region is not tagged as such
       // outside a GC operation
       assert(!alloc_region->is_gc_alloc_region(), "sanity");
       if (alloc_region->in_collection_set() ||
           alloc_region->top() == alloc_region->end() ||
           alloc_region->top() == alloc_region->bottom() ||
           alloc_region->isHumongous()) {
         // we will discard the current GC alloc region if
         // * it's in the collection set (it can happen!),
         // * it's already full (no point in using it),
         // * it's empty (this means that it was emptied during
         // a cleanup and it should be on the free list now), or
         // * it's humongous (this means that it was emptied
         // during a cleanup and was added to the free list, but
         // has been subseqently used to allocate a humongous
         // object that may be less than the region size).
         alloc_region = NULL;
       }
     }
     if (alloc_region == NULL) {
       // we will get a new GC alloc region
       alloc_region = newAllocRegionWithExpansion(ap, 0);
     } else {
       // the region was retained from the last collection
       ++_gc_alloc_region_counts[ap];
       if (G1PrintHeapRegions) {
         gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
                                "top "PTR_FORMAT,
                                alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top());
       }
     }
     if (alloc_region != NULL) {
       assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
       set_gc_alloc_region(ap, alloc_region);
     }
     assert(_gc_alloc_regions[ap] == NULL ||
            _gc_alloc_regions[ap]->is_gc_alloc_region(),
            "the GC alloc region should be tagged as such");
     assert(_gc_alloc_regions[ap] == NULL ||
            _gc_alloc_regions[ap] == _gc_alloc_region_list,
            "the GC alloc region should be the same as the GC alloc list head");
   }
   // Set alternative regions for allocation purposes that have reached
   // their limit.
   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
     GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
     if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
       _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
     }
   }
   assert(check_gc_alloc_regions(), "alloc regions messed up");
 }
 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
   // We keep a separate list of all regions that have been alloc regions in
   // the current collection pause. Forget that now. This method will
   // untag the GC alloc regions and tear down the GC alloc region
   // list. It's desirable that no regions are tagged as GC alloc
   // outside GCs.
   forget_alloc_region_list();
   // The current alloc regions contain objs that have survived
   // collection. Make them no longer GC alloc regions.
   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
     HeapRegion* r = _gc_alloc_regions[ap];
     _retained_gc_alloc_regions[ap] = NULL;
     _gc_alloc_region_counts[ap] = 0;
     if (r != NULL) {
       // we retain nothing on _gc_alloc_regions between GCs
       set_gc_alloc_region(ap, NULL);
       if (r->is_empty()) {
         // we didn't actually allocate anything in it; let's just put
         // it on the free list
         MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
         r->set_zero_fill_complete();
         put_free_region_on_list_locked(r);
       } else if (_retain_gc_alloc_region[ap] && !totally) {
         // retain it so that we can use it at the beginning of the next GC
         _retained_gc_alloc_regions[ap] = r;
       }
     }
   }
 }
 #ifndef PRODUCT
 // Useful for debugging
 void G1CollectedHeap::print_gc_alloc_regions() {
   gclog_or_tty->print_cr("GC alloc regions");
   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
     HeapRegion* r = _gc_alloc_regions[ap];
     if (r == NULL) {
       gclog_or_tty->print_cr("  %2d : "PTR_FORMAT, ap, NULL);
     } else {
       gclog_or_tty->print_cr("  %2d : "PTR_FORMAT" "SIZE_FORMAT,
                              ap, r->bottom(), r->used());
     }
   }
 }
 #endif // PRODUCT
 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
   _drain_in_progress = false;
   set_evac_failure_closure(cl);
   _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
 }
 void G1CollectedHeap::finalize_for_evac_failure() {
   assert(_evac_failure_scan_stack != NULL &&
          _evac_failure_scan_stack->length() == 0,
          "Postcondition");
   assert(!_drain_in_progress, "Postcondition");
   delete _evac_failure_scan_stack;
   _evac_failure_scan_stack = NULL;
 }
 // *** Sequential G1 Evacuation
 HeapWord* G1CollectedHeap::allocate_during_gc(GCAllocPurpose purpose, size_t word_size) {
   HeapRegion* alloc_region = _gc_alloc_regions[purpose];
   // let the caller handle alloc failure
   if (alloc_region == NULL) return NULL;
   assert(isHumongous(word_size) || !alloc_region->isHumongous(),
          "Either the object is humongous or the region isn't");
   HeapWord* block = alloc_region->allocate(word_size);
   if (block == NULL) {
     block = allocate_during_gc_slow(purpose, alloc_region, false, word_size);
   }
   return block;
 }
 class G1IsAliveClosure: public BoolObjectClosure {
   G1CollectedHeap* _g1;
 public:
   G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
   void do_object(oop p) { assert(false, "Do not call."); }
   bool do_object_b(oop p) {
     // It is reachable if it is outside the collection set, or is inside
     // and forwarded.
 #ifdef G1_DEBUG
     gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
                            (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
                            !_g1->obj_in_cs(p) || p->is_forwarded());
 #endif // G1_DEBUG
     return !_g1->obj_in_cs(p) || p->is_forwarded();
   }
 };
 class G1KeepAliveClosure: public OopClosure {
   G1CollectedHeap* _g1;
 public:
   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
   void do_oop(      oop* p) {
     oop obj = *p;
 #ifdef G1_DEBUG
     if (PrintGC && Verbose) {
       gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
                              p, (void*) obj, (void*) *p);
     }
 #endif // G1_DEBUG
     if (_g1->obj_in_cs(obj)) {
       assert( obj->is_forwarded(), "invariant" );
       *p = obj->forwardee();
 #ifdef G1_DEBUG
       gclog_or_tty->print_cr("     in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
                              (void*) obj, (void*) *p);
 #endif // G1_DEBUG
     }
   }
 };
 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
 private:
   G1CollectedHeap* _g1;
   DirtyCardQueue *_dcq;
   CardTableModRefBS* _ct_bs;
 public:
   UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
     _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
   virtual void do_oop(      oop* p) { do_oop_work(p); }
   template <class T> void do_oop_work(T* p) {
     assert(_from->is_in_reserved(p), "paranoia");
     if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
         !_from->is_survivor()) {
       size_t card_index = _ct_bs->index_for(p);
       if (_ct_bs->mark_card_deferred(card_index)) {
         _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
       }
     }
   }
 };
 class RemoveSelfPointerClosure: public ObjectClosure {
 private:
   G1CollectedHeap* _g1;
   ConcurrentMark* _cm;
   HeapRegion* _hr;
   size_t _prev_marked_bytes;
   size_t _next_marked_bytes;
   OopsInHeapRegionClosure *_cl;
 public:
   RemoveSelfPointerClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* cl) :
     _g1(g1), _cm(_g1->concurrent_mark()),  _prev_marked_bytes(0),
     _next_marked_bytes(0), _cl(cl) {}
   size_t prev_marked_bytes() { return _prev_marked_bytes; }
   size_t next_marked_bytes() { return _next_marked_bytes; }
   // The original idea here was to coalesce evacuated and dead objects.
   // However that caused complications with the block offset table (BOT).
   // In particular if there were two TLABs, one of them partially refined.
   // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
   // The BOT entries of the unrefined part of TLAB_2 point to the start
   // of TLAB_2. If the last object of the TLAB_1 and the first object
   // of TLAB_2 are coalesced, then the cards of the unrefined part
   // would point into middle of the filler object.
   //
   // The current approach is to not coalesce and leave the BOT contents intact.
   void do_object(oop obj) {
     if (obj->is_forwarded() && obj->forwardee() == obj) {
       // The object failed to move.
       assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
       _cm->markPrev(obj);
       assert(_cm->isPrevMarked(obj), "Should be marked!");
       _prev_marked_bytes += (obj->size() * HeapWordSize);
       if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
         _cm->markAndGrayObjectIfNecessary(obj);
       }
       obj->set_mark(markOopDesc::prototype());
       // While we were processing RSet buffers during the
       // collection, we actually didn't scan any cards on the
       // collection set, since we didn't want to update remebered
       // sets with entries that point into the collection set, given
       // that live objects fromthe collection set are about to move
       // and such entries will be stale very soon. This change also
       // dealt with a reliability issue which involved scanning a
       // card in the collection set and coming across an array that
       // was being chunked and looking malformed. The problem is
       // that, if evacuation fails, we might have remembered set
       // entries missing given that we skipped cards on the
       // collection set. So, we'll recreate such entries now.
       obj->oop_iterate(_cl);
       assert(_cm->isPrevMarked(obj), "Should be marked!");
     } else {
       // The object has been either evacuated or is dead. Fill it with a
       // dummy object.
       MemRegion mr((HeapWord*)obj, obj->size());
       CollectedHeap::fill_with_object(mr);
       _cm->clearRangeBothMaps(mr);
     }
   }
 };
 void G1CollectedHeap::remove_self_forwarding_pointers() {
   UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
   DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
   UpdateRSetDeferred deferred_update(_g1h, &dcq);
   OopsInHeapRegionClosure *cl;
   if (G1DeferredRSUpdate) {
     cl = &deferred_update;
   } else {
     cl = &immediate_update;
   }
   HeapRegion* cur = g1_policy()->collection_set();
   while (cur != NULL) {
     assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
     RemoveSelfPointerClosure rspc(_g1h, cl);
     if (cur->evacuation_failed()) {
       assert(cur->in_collection_set(), "bad CS");
       cl->set_region(cur);
       cur->object_iterate(&rspc);
       // A number of manipulations to make the TAMS be the current top,
       // and the marked bytes be the ones observed in the iteration.
       if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
         // The comments below are the postconditions achieved by the
         // calls.  Note especially the last such condition, which says that
         // the count of marked bytes has been properly restored.
         cur->note_start_of_marking(false);
         // _next_top_at_mark_start == top, _next_marked_bytes == 0
         cur->add_to_marked_bytes(rspc.prev_marked_bytes());
         // _next_marked_bytes == prev_marked_bytes.
         cur->note_end_of_marking();
         // _prev_top_at_mark_start == top(),
         // _prev_marked_bytes == prev_marked_bytes
       }
       // If there is no mark in progress, we modified the _next variables
       // above needlessly, but harmlessly.
       if (_g1h->mark_in_progress()) {
         cur->note_start_of_marking(false);
         // _next_top_at_mark_start == top, _next_marked_bytes == 0
         // _next_marked_bytes == next_marked_bytes.
       }
       // Now make sure the region has the right index in the sorted array.
       g1_policy()->note_change_in_marked_bytes(cur);
     }
     cur = cur->next_in_collection_set();
   }
   assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
   // Now restore saved marks, if any.
   if (_objs_with_preserved_marks != NULL) {
     assert(_preserved_marks_of_objs != NULL, "Both or none.");
     assert(_objs_with_preserved_marks->length() ==
            _preserved_marks_of_objs->length(), "Both or none.");
     guarantee(_objs_with_preserved_marks->length() ==
               _preserved_marks_of_objs->length(), "Both or none.");
     for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
       oop obj   = _objs_with_preserved_marks->at(i);
       markOop m = _preserved_marks_of_objs->at(i);
       obj->set_mark(m);
     }
     // Delete the preserved marks growable arrays (allocated on the C heap).
     delete _objs_with_preserved_marks;
     delete _preserved_marks_of_objs;
     _objs_with_preserved_marks = NULL;
     _preserved_marks_of_objs = NULL;
   }
 }
 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
   _evac_failure_scan_stack->push(obj);
 }
 void G1CollectedHeap::drain_evac_failure_scan_stack() {
   assert(_evac_failure_scan_stack != NULL, "precondition");
   while (_evac_failure_scan_stack->length() > 0) {
      oop obj = _evac_failure_scan_stack->pop();
      _evac_failure_closure->set_region(heap_region_containing(obj));
      obj->oop_iterate_backwards(_evac_failure_closure);
   }
 }
 void G1CollectedHeap::handle_evacuation_failure(oop old) {
   markOop m = old->mark();
   // forward to self
   assert(!old->is_forwarded(), "precondition");
   old->forward_to(old);
   handle_evacuation_failure_common(old, m);
 }
 oop
 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
                                                oop old) {
   markOop m = old->mark();
   oop forward_ptr = old->forward_to_atomic(old);
   if (forward_ptr == NULL) {
     // Forward-to-self succeeded.
     if (_evac_failure_closure != cl) {
       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
       assert(!_drain_in_progress,
              "Should only be true while someone holds the lock.");
       // Set the global evac-failure closure to the current thread's.
       assert(_evac_failure_closure == NULL, "Or locking has failed.");
       set_evac_failure_closure(cl);
       // Now do the common part.
       handle_evacuation_failure_common(old, m);
       // Reset to NULL.
       set_evac_failure_closure(NULL);
     } else {
       // The lock is already held, and this is recursive.
       assert(_drain_in_progress, "This should only be the recursive case.");
       handle_evacuation_failure_common(old, m);
     }
     return old;
   } else {
     // Someone else had a place to copy it.
     return forward_ptr;
   }
 }
 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
   set_evacuation_failed(true);
   preserve_mark_if_necessary(old, m);
   HeapRegion* r = heap_region_containing(old);
   if (!r->evacuation_failed()) {
     r->set_evacuation_failed(true);
     if (G1PrintHeapRegions) {
       gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
                           "["PTR_FORMAT","PTR_FORMAT")\n",
                           r, r->bottom(), r->end());
     }
   }
   push_on_evac_failure_scan_stack(old);
   if (!_drain_in_progress) {
     // prevent recursion in copy_to_survivor_space()
     _drain_in_progress = true;
     drain_evac_failure_scan_stack();
     _drain_in_progress = false;
   }
 }
 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
   if (m != markOopDesc::prototype()) {
     if (_objs_with_preserved_marks == NULL) {
       assert(_preserved_marks_of_objs == NULL, "Both or none.");
       _objs_with_preserved_marks =
         new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
       _preserved_marks_of_objs =
         new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
     }
     _objs_with_preserved_marks->push(obj);
     _preserved_marks_of_objs->push(m);
   }
 }
 // *** Parallel G1 Evacuation
 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
                                                   size_t word_size) {
   HeapRegion* alloc_region = _gc_alloc_regions[purpose];
   // let the caller handle alloc failure
   if (alloc_region == NULL) return NULL;
   HeapWord* block = alloc_region->par_allocate(word_size);
   if (block == NULL) {
     MutexLockerEx x(par_alloc_during_gc_lock(),
                     Mutex::_no_safepoint_check_flag);
     block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
   }
   return block;
 }
 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
                                             bool par) {
   // Another thread might have obtained alloc_region for the given
   // purpose, and might be attempting to allocate in it, and might
   // succeed.  Therefore, we can't do the "finalization" stuff on the
   // region below until we're sure the last allocation has happened.
   // We ensure this by allocating the remaining space with a garbage
   // object.
   if (par) par_allocate_remaining_space(alloc_region);
   // Now we can do the post-GC stuff on the region.
   alloc_region->note_end_of_copying();
   g1_policy()->record_after_bytes(alloc_region->used());
 }
 HeapWord*
 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
                                          HeapRegion*    alloc_region,
                                          bool           par,
                                          size_t         word_size) {
   HeapWord* block = NULL;
   // In the parallel case, a previous thread to obtain the lock may have
   // already assigned a new gc_alloc_region.
   if (alloc_region != _gc_alloc_regions[purpose]) {
     assert(par, "But should only happen in parallel case.");
     alloc_region = _gc_alloc_regions[purpose];
     if (alloc_region == NULL) return NULL;
     block = alloc_region->par_allocate(word_size);
     if (block != NULL) return block;
     // Otherwise, continue; this new region is empty, too.
   }
   assert(alloc_region != NULL, "We better have an allocation region");
   retire_alloc_region(alloc_region, par);
   if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
     // Cannot allocate more regions for the given purpose.
     GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
     // Is there an alternative?
     if (purpose != alt_purpose) {
       HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
       // Has not the alternative region been aliased?
       if (alloc_region != alt_region && alt_region != NULL) {
         // Try to allocate in the alternative region.
         if (par) {
           block = alt_region->par_allocate(word_size);
         } else {
           block = alt_region->allocate(word_size);
         }
         // Make an alias.
         _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
         if (block != NULL) {
           return block;
         }
         retire_alloc_region(alt_region, par);
       }
       // Both the allocation region and the alternative one are full
       // and aliased, replace them with a new allocation region.
       purpose = alt_purpose;
     } else {
       set_gc_alloc_region(purpose, NULL);
       return NULL;
     }
   }
   // Now allocate a new region for allocation.
   alloc_region = newAllocRegionWithExpansion(purpose, word_size, false /*zero_filled*/);
   // let the caller handle alloc failure
   if (alloc_region != NULL) {
     assert(check_gc_alloc_regions(), "alloc regions messed up");
     assert(alloc_region->saved_mark_at_top(),
            "Mark should have been saved already.");
     // We used to assert that the region was zero-filled here, but no
     // longer.
     // This must be done last: once it's installed, other regions may
     // allocate in it (without holding the lock.)
     set_gc_alloc_region(purpose, alloc_region);
     if (par) {
       block = alloc_region->par_allocate(word_size);
     } else {
       block = alloc_region->allocate(word_size);
     }
     // Caller handles alloc failure.
   } else {
     // This sets other apis using the same old alloc region to NULL, also.
     set_gc_alloc_region(purpose, NULL);
   }
   return block;  // May be NULL.
 }
 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
   HeapWord* block = NULL;
   size_t free_words;
   do {
     free_words = r->free()/HeapWordSize;
     // If there's too little space, no one can allocate, so we're done.
     if (free_words < CollectedHeap::min_fill_size()) return;
     // Otherwise, try to claim it.
     block = r->par_allocate(free_words);
   } while (block == NULL);
   fill_with_object(block, free_words);
 }
 #ifndef PRODUCT
 bool GCLabBitMapClosure::do_bit(size_t offset) {
   HeapWord* addr = _bitmap->offsetToHeapWord(offset);
   guarantee(_cm->isMarked(oop(addr)), "it should be!");
   return true;
 }
 #endif // PRODUCT
 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
   : _g1h(g1h),
     _refs(g1h->task_queue(queue_num)),
     _dcq(&g1h->dirty_card_queue_set()),
     _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
     _g1_rem(g1h->g1_rem_set()),
     _hash_seed(17), _queue_num(queue_num),
     _term_attempts(0),
     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
     _age_table(false),
     _strong_roots_time(0), _term_time(0),
     _alloc_buffer_waste(0), _undo_waste(0)
 {
   // we allocate G1YoungSurvRateNumRegions plus one entries, since
   // we "sacrifice" entry 0 to keep track of surviving bytes for
   // non-young regions (where the age is -1)
   // We also add a few elements at the beginning and at the end in
   // an attempt to eliminate cache contention
   size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
   size_t array_length = PADDING_ELEM_NUM +
                         real_length +
                         PADDING_ELEM_NUM;
   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
   if (_surviving_young_words_base == NULL)
     vm_exit_out_of_memory(array_length * sizeof(size_t),
                           "Not enough space for young surv histo.");
   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
   memset(_surviving_young_words, 0, real_length * sizeof(size_t));
   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
   _start = os::elapsedTime();
 }
 void
 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
 {
   st->print_raw_cr("GC Termination Stats");
   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
                    " ------waste (KiB)------");
   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
                    "  total   alloc    undo");
   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
                    " ------- ------- -------");
 }
 void
 G1ParScanThreadState::print_termination_stats(int i,
                                               outputStream* const st) const
 {
   const double elapsed_ms = elapsed_time() * 1000.0;
   const double s_roots_ms = strong_roots_time() * 1000.0;
   const double term_ms    = term_time() * 1000.0;
   st->print_cr("%3d %9.2f %9.2f %6.2f "
                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
                alloc_buffer_waste() * HeapWordSize / K,
                undo_waste() * HeapWordSize / K);
 }
 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
   _par_scan_state(par_scan_state) { }
 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
   // This is called _after_ do_oop_work has been called, hence after
   // the object has been relocated to its new location and *p points
   // to its new location.
   T heap_oop = oopDesc::load_heap_oop(p);
   if (!oopDesc::is_null(heap_oop)) {
     oop obj = oopDesc::decode_heap_oop(heap_oop);
     assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
            "shouldn't still be in the CSet if evacuation didn't fail.");
     HeapWord* addr = (HeapWord*)obj;
     if (_g1->is_in_g1_reserved(addr))
       _cm->grayRoot(oop(addr));
   }
 }
 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
   size_t    word_sz = old->size();
   HeapRegion* from_region = _g1->heap_region_containing_raw(old);
   // +1 to make the -1 indexes valid...
   int       young_index = from_region->young_index_in_cset()+1;
   assert( (from_region->is_young() && young_index > 0) ||
           (!from_region->is_young() && young_index == 0), "invariant" );
   G1CollectorPolicy* g1p = _g1->g1_policy();
   markOop m = old->mark();
   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
                                            : m->age();
   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
                                                              word_sz);
   HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
   oop       obj     = oop(obj_ptr);
   if (obj_ptr == NULL) {
     // This will either forward-to-self, or detect that someone else has
     // installed a forwarding pointer.
     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
     return _g1->handle_evacuation_failure_par(cl, old);
   }
   // We're going to allocate linearly, so might as well prefetch ahead.
   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
   oop forward_ptr = old->forward_to_atomic(obj);
   if (forward_ptr == NULL) {
     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
     if (g1p->track_object_age(alloc_purpose)) {
       // We could simply do obj->incr_age(). However, this causes a
       // performance issue. obj->incr_age() will first check whether
       // the object has a displaced mark by checking its mark word;
       // getting the mark word from the new location of the object
       // stalls. So, given that we already have the mark word and we
       // are about to install it anyway, it's better to increase the
       // age on the mark word, when the object does not have a
       // displaced mark word. We're not expecting many objects to have
       // a displaced marked word, so that case is not optimized
       // further (it could be...) and we simply call obj->incr_age().
       if (m->has_displaced_mark_helper()) {
         // in this case, we have to install the mark word first,
         // otherwise obj looks to be forwarded (the old mark word,
         // which contains the forward pointer, was copied)
         obj->set_mark(m);
         obj->incr_age();
       } else {
         m = m->incr_age();
         obj->set_mark(m);
       }
       _par_scan_state->age_table()->add(obj, word_sz);
     } else {
       obj->set_mark(m);
     }
     // preserve "next" mark bit
     if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
       if (!use_local_bitmaps ||
           !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
         // if we couldn't mark it on the local bitmap (this happens when
         // the object was not allocated in the GCLab), we have to bite
         // the bullet and do the standard parallel mark
         _cm->markAndGrayObjectIfNecessary(obj);
       }
 #if 1
       if (_g1->isMarkedNext(old)) {
         _cm->nextMarkBitMap()->parClear((HeapWord*)old);
       }
 #endif
     }
     size_t* surv_young_words = _par_scan_state->surviving_young_words();
     surv_young_words[young_index] += word_sz;
     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
       arrayOop(old)->set_length(0);
       oop* old_p = set_partial_array_mask(old);
       _par_scan_state->push_on_queue(old_p);
     } else {
       // No point in using the slower heap_region_containing() method,
       // given that we know obj is in the heap.
       _scanner->set_region(_g1->heap_region_containing_raw(obj));
       obj->oop_iterate_backwards(_scanner);
     }
   } else {
     _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
     obj = forward_ptr;
   }
   return obj;
 }
 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
 template <class T>
 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
 ::do_oop_work(T* p) {
   oop obj = oopDesc::load_decode_heap_oop(p);
   assert(barrier != G1BarrierRS || obj != NULL,
          "Precondition: G1BarrierRS implies obj is nonNull");
   // here the null check is implicit in the cset_fast_test() test
   if (_g1->in_cset_fast_test(obj)) {
 #if G1_REM_SET_LOGGING
     gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
                            "into CS.", p, (void*) obj);
 #endif
     if (obj->is_forwarded()) {
       oopDesc::encode_store_heap_oop(p, obj->forwardee());
     } else {
       oop copy_oop = copy_to_survivor_space(obj);
       oopDesc::encode_store_heap_oop(p, copy_oop);
     }
     // When scanning the RS, we only care about objs in CS.
     if (barrier == G1BarrierRS) {
       _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
     }
   }
   if (barrier == G1BarrierEvac && obj != NULL) {
     _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
   }
   if (do_gen_barrier && obj != NULL) {
     par_do_barrier(p);
   }
 }
 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
   assert(has_partial_array_mask(p), "invariant");
   oop old = clear_partial_array_mask(p);
   assert(old->is_objArray(), "must be obj array");
   assert(old->is_forwarded(), "must be forwarded");
   assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
   objArrayOop obj = objArrayOop(old->forwardee());
   assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
   // Process ParGCArrayScanChunk elements now
   // and push the remainder back onto queue
   int start     = arrayOop(old)->length();
   int end       = obj->length();
   int remainder = end - start;
   assert(start <= end, "just checking");
   if (remainder > 2 * ParGCArrayScanChunk) {
     // Test above combines last partial chunk with a full chunk
     end = start + ParGCArrayScanChunk;
     arrayOop(old)->set_length(end);
     // Push remainder.
     oop* old_p = set_partial_array_mask(old);
     assert(arrayOop(old)->length() < obj->length(), "Empty push?");
     _par_scan_state->push_on_queue(old_p);
   } else {
     // Restore length so that the heap remains parsable in
     // case of evacuation failure.
     arrayOop(old)->set_length(end);
   }
   _scanner.set_region(_g1->heap_region_containing_raw(obj));
   // process our set of indices (include header in first chunk)
   obj->oop_iterate_range(&_scanner, start, end);
 }
 class G1ParEvacuateFollowersClosure : public VoidClosure {
 protected:
   G1CollectedHeap*              _g1h;
   G1ParScanThreadState*         _par_scan_state;
   RefToScanQueueSet*            _queues;
   ParallelTaskTerminator*       _terminator;
   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
   RefToScanQueueSet*      queues()         { return _queues; }
   ParallelTaskTerminator* terminator()     { return _terminator; }
 public:
   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
                                 G1ParScanThreadState* par_scan_state,
                                 RefToScanQueueSet* queues,
                                 ParallelTaskTerminator* terminator)
     : _g1h(g1h), _par_scan_state(par_scan_state),
       _queues(queues), _terminator(terminator) {}
   void do_void() {
     G1ParScanThreadState* pss = par_scan_state();
     while (true) {
       pss->trim_queue();
       StarTask stolen_task;
       if (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
         // slightly paranoid tests; I'm trying to catch potential
         // problems before we go into push_on_queue to know where the
         // problem is coming from
         assert((oop*)stolen_task != NULL, "Error");
         if (stolen_task.is_narrow()) {
           assert(UseCompressedOops, "Error");
           narrowOop* p = (narrowOop*) stolen_task;
           assert(has_partial_array_mask(p) ||
                  _g1h->is_in_g1_reserved(oopDesc::load_decode_heap_oop(p)), "Error");
           pss->push_on_queue(p);
         } else {
           oop* p = (oop*) stolen_task;
           assert(has_partial_array_mask(p) || _g1h->is_in_g1_reserved(*p), "Error");
           pss->push_on_queue(p);
         }
         continue;
       }
       pss->start_term_time();
       if (terminator()->offer_termination()) break;
       pss->end_term_time();
     }
     pss->end_term_time();
     pss->retire_alloc_buffers();
   }
 };
 class G1ParTask : public AbstractGangTask {
 protected:
   G1CollectedHeap*       _g1h;
   RefToScanQueueSet      *_queues;
   ParallelTaskTerminator _terminator;
   int _n_workers;
   Mutex _stats_lock;
   Mutex* stats_lock() { return &_stats_lock; }
   size_t getNCards() {
     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
       / G1BlockOffsetSharedArray::N_bytes;
   }
 public:
   G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
     : AbstractGangTask("G1 collection"),
       _g1h(g1h),
       _queues(task_queues),
       _terminator(workers, _queues),
       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
       _n_workers(workers)
   {}
   RefToScanQueueSet* queues() { return _queues; }
   RefToScanQueue *work_queue(int i) {
     return queues()->queue(i);
   }
   void work(int i) {
     if (i >= _n_workers) return;  // no work needed this round
     double start_time_ms = os::elapsedTime() * 1000.0;
     _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
     ResourceMark rm;
     HandleMark   hm;
     G1ParScanThreadState            pss(_g1h, i);
     G1ParScanHeapEvacClosure        scan_evac_cl(_g1h, &pss);
     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
     G1ParScanPartialArrayClosure    partial_scan_cl(_g1h, &pss);
     pss.set_evac_closure(&scan_evac_cl);
     pss.set_evac_failure_closure(&evac_failure_cl);
     pss.set_partial_scan_closure(&partial_scan_cl);
     G1ParScanExtRootClosure         only_scan_root_cl(_g1h, &pss);
     G1ParScanPermClosure            only_scan_perm_cl(_g1h, &pss);
     G1ParScanHeapRSClosure          only_scan_heap_rs_cl(_g1h, &pss);
     G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
     G1ParScanAndMarkExtRootClosure  scan_mark_root_cl(_g1h, &pss);
     G1ParScanAndMarkPermClosure     scan_mark_perm_cl(_g1h, &pss);
     G1ParScanAndMarkHeapRSClosure   scan_mark_heap_rs_cl(_g1h, &pss);
     OopsInHeapRegionClosure        *scan_root_cl;
     OopsInHeapRegionClosure        *scan_perm_cl;
     if (_g1h->g1_policy()->during_initial_mark_pause()) {
       scan_root_cl = &scan_mark_root_cl;
       scan_perm_cl = &scan_mark_perm_cl;
     } else {
       scan_root_cl = &only_scan_root_cl;
       scan_perm_cl = &only_scan_perm_cl;
     }
     pss.start_strong_roots();
     _g1h->g1_process_strong_roots(/* not collecting perm */ false,
                                   SharedHeap::SO_AllClasses,
                                   scan_root_cl,
                                   &push_heap_rs_cl,
                                   scan_perm_cl,
                                   i);
     pss.end_strong_roots();
     {
       double start = os::elapsedTime();
       G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
       evac.do_void();
       double elapsed_ms = (os::elapsedTime()-start)*1000.0;
       double term_ms = pss.term_time()*1000.0;
       _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
       _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
     }
     _g1h->g1_policy()->record_thread_age_table(pss.age_table());
     _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
     // Clean up any par-expanded rem sets.
     HeapRegionRemSet::par_cleanup();
     if (ParallelGCVerbose) {
       MutexLocker x(stats_lock());
       pss.print_termination_stats(i);
     }
     assert(pss.refs_to_scan() == 0, "Task queue should be empty");
     assert(pss.overflowed_refs_to_scan() == 0, "Overflow queue should be empty");
     double end_time_ms = os::elapsedTime() * 1000.0;
     _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
   }
 };
 // *** Common G1 Evacuation Stuff
 void
 G1CollectedHeap::
 g1_process_strong_roots(bool collecting_perm_gen,
                         SharedHeap::ScanningOption so,
                         OopClosure* scan_non_heap_roots,
                         OopsInHeapRegionClosure* scan_rs,
                         OopsInGenClosure* scan_perm,
                         int worker_i) {
   // First scan the strong roots, including the perm gen.
   double ext_roots_start = os::elapsedTime();
   double closure_app_time_sec = 0.0;
   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
   BufferingOopsInGenClosure buf_scan_perm(scan_perm);
   buf_scan_perm.set_generation(perm_gen());
   // Walk the code cache w/o buffering, because StarTask cannot handle
   // unaligned oop locations.
   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
   process_strong_roots(false, // no scoping; this is parallel code
                        collecting_perm_gen, so,
                        &buf_scan_non_heap_roots,
                        &eager_scan_code_roots,
                        &buf_scan_perm);
   // Finish up any enqueued closure apps.
   buf_scan_non_heap_roots.done();
   buf_scan_perm.done();
   double ext_roots_end = os::elapsedTime();
   g1_policy()->reset_obj_copy_time(worker_i);
   double obj_copy_time_sec =
     buf_scan_non_heap_roots.closure_app_seconds() +
     buf_scan_perm.closure_app_seconds();
   g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
   double ext_root_time_ms =
     ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
   g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
   // Scan strong roots in mark stack.
   if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
     concurrent_mark()->oops_do(scan_non_heap_roots);
   }
   double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
   g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
   // XXX What should this be doing in the parallel case?
   g1_policy()->record_collection_pause_end_CH_strong_roots();
   // Now scan the complement of the collection set.
   if (scan_rs != NULL) {
     g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
   }
   // Finish with the ref_processor roots.
   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
     ref_processor()->oops_do(scan_non_heap_roots);
   }
   g1_policy()->record_collection_pause_end_G1_strong_roots();
   _process_strong_tasks->all_tasks_completed();
 }
 void
 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
                                        OopClosure* non_root_closure) {
   CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
   SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
 }
 class SaveMarksClosure: public HeapRegionClosure {
 public:
   bool doHeapRegion(HeapRegion* r) {
     r->save_marks();
     return false;
   }
 };
 void G1CollectedHeap::save_marks() {
   if (ParallelGCThreads == 0) {
     SaveMarksClosure sm;
     heap_region_iterate(&sm);
   }
   // We do this even in the parallel case
   perm_gen()->save_marks();
 }
 void G1CollectedHeap::evacuate_collection_set() {
   set_evacuation_failed(false);
   g1_rem_set()->prepare_for_oops_into_collection_set_do();
   concurrent_g1_refine()->set_use_cache(false);
   concurrent_g1_refine()->clear_hot_cache_claimed_index();
   int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
   set_par_threads(n_workers);
   G1ParTask g1_par_task(this, n_workers, _task_queues);
   init_for_evac_failure(NULL);
   rem_set()->prepare_for_younger_refs_iterate(true);
   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
   double start_par = os::elapsedTime();
   if (ParallelGCThreads > 0) {
     // The individual threads will set their evac-failure closures.
     StrongRootsScope srs(this);
     if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
     workers()->run_task(&g1_par_task);
   } else {
     StrongRootsScope srs(this);
     g1_par_task.work(0);
   }
   double par_time = (os::elapsedTime() - start_par) * 1000.0;
   g1_policy()->record_par_time(par_time);
   set_par_threads(0);
   // Is this the right thing to do here?  We don't save marks
   // on individual heap regions when we allocate from
   // them in parallel, so this seems like the correct place for this.
   retire_all_alloc_regions();
   {
     G1IsAliveClosure is_alive(this);
     G1KeepAliveClosure keep_alive(this);
     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
   }
   release_gc_alloc_regions(false /* totally */);
   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
   concurrent_g1_refine()->clear_hot_cache();
   concurrent_g1_refine()->set_use_cache(true);
   finalize_for_evac_failure();
   // Must do this before removing self-forwarding pointers, which clears
   // the per-region evac-failure flags.
   concurrent_mark()->complete_marking_in_collection_set();
   if (evacuation_failed()) {
     remove_self_forwarding_pointers();
     if (PrintGCDetails) {
       gclog_or_tty->print(" (evacuation failed)");
     } else if (PrintGC) {
       gclog_or_tty->print("--");
     }
   }
   if (G1DeferredRSUpdate) {
     RedirtyLoggedCardTableEntryFastClosure redirty;
     dirty_card_queue_set().set_closure(&redirty);
     dirty_card_queue_set().apply_closure_to_all_completed_buffers();
     DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
     dcq.merge_bufferlists(&dirty_card_queue_set());
     assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
   }
   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 }
 void G1CollectedHeap::free_region(HeapRegion* hr) {
   size_t pre_used = 0;
   size_t cleared_h_regions = 0;
   size_t freed_regions = 0;
   UncleanRegionList local_list;
   HeapWord* start = hr->bottom();
   HeapWord* end   = hr->prev_top_at_mark_start();
   size_t used_bytes = hr->used();
   size_t live_bytes = hr->max_live_bytes();
   if (used_bytes > 0) {
     guarantee( live_bytes <= used_bytes, "invariant" );
   } else {
     guarantee( live_bytes == 0, "invariant" );
   }
   size_t garbage_bytes = used_bytes - live_bytes;
   if (garbage_bytes > 0)
     g1_policy()->decrease_known_garbage_bytes(garbage_bytes);
   free_region_work(hr, pre_used, cleared_h_regions, freed_regions,
                    &local_list);
   finish_free_region_work(pre_used, cleared_h_regions, freed_regions,
                           &local_list);
 }
 void
 G1CollectedHeap::free_region_work(HeapRegion* hr,
                                   size_t& pre_used,
                                   size_t& cleared_h_regions,
                                   size_t& freed_regions,
                                   UncleanRegionList* list,
                                   bool par) {
   pre_used += hr->used();
   if (hr->isHumongous()) {
     assert(hr->startsHumongous(),
            "Only the start of a humongous region should be freed.");
     int ind = _hrs->find(hr);
     assert(ind != -1, "Should have an index.");
     // Clear the start region.
     hr->hr_clear(par, true /*clear_space*/);
     list->insert_before_head(hr);
     cleared_h_regions++;
     freed_regions++;
     // Clear any continued regions.
     ind++;
     while ((size_t)ind < n_regions()) {
       HeapRegion* hrc = _hrs->at(ind);
       if (!hrc->continuesHumongous()) break;
       // Otherwise, does continue the H region.
       assert(hrc->humongous_start_region() == hr, "Huh?");
       hrc->hr_clear(par, true /*clear_space*/);
       cleared_h_regions++;
       freed_regions++;
       list->insert_before_head(hrc);
       ind++;
     }
   } else {
     hr->hr_clear(par, true /*clear_space*/);
     list->insert_before_head(hr);
     freed_regions++;
     // If we're using clear2, this should not be enabled.
     // assert(!hr->in_cohort(), "Can't be both free and in a cohort.");
   }
 }
 void G1CollectedHeap::finish_free_region_work(size_t pre_used,
                                               size_t cleared_h_regions,
                                               size_t freed_regions,
                                               UncleanRegionList* list) {
   if (list != NULL && list->sz() > 0) {
     prepend_region_list_on_unclean_list(list);
   }
   // Acquire a lock, if we're parallel, to update possibly-shared
   // variables.
   Mutex* lock = (n_par_threads() > 0) ? ParGCRareEvent_lock : NULL;
   {
     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
     _summary_bytes_used -= pre_used;
     _num_humongous_regions -= (int) cleared_h_regions;
     _free_regions += freed_regions;
   }
 }
 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
   while (list != NULL) {
     guarantee( list->is_young(), "invariant" );
     HeapWord* bottom = list->bottom();
     HeapWord* end = list->end();
     MemRegion mr(bottom, end);
     ct_bs->dirty(mr);
     list = list->get_next_young_region();
   }
 }
 class G1ParCleanupCTTask : public AbstractGangTask {
   CardTableModRefBS* _ct_bs;
   G1CollectedHeap* _g1h;
   HeapRegion* volatile _su_head;
 public:
   G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
                      G1CollectedHeap* g1h,
                      HeapRegion* survivor_list) :
     AbstractGangTask("G1 Par Cleanup CT Task"),
     _ct_bs(ct_bs),
     _g1h(g1h),
     _su_head(survivor_list)
   { }
   void work(int i) {
     HeapRegion* r;
     while (r = _g1h->pop_dirty_cards_region()) {
       clear_cards(r);
     }
     // Redirty the cards of the survivor regions.
     dirty_list(&this->_su_head);
   }
   void clear_cards(HeapRegion* r) {
     // Cards for Survivor regions will be dirtied later.
     if (!r->is_survivor()) {
       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
     }
   }
   void dirty_list(HeapRegion* volatile * head_ptr) {
     HeapRegion* head;
     do {
       // Pop region off the list.
       head = *head_ptr;
       if (head != NULL) {
         HeapRegion* r = (HeapRegion*)
           Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
         if (r == head) {
           assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
           _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
         }
       }
     } while (*head_ptr != NULL);
   }
 };
 #ifndef PRODUCT
 class G1VerifyCardTableCleanup: public HeapRegionClosure {
   CardTableModRefBS* _ct_bs;
 public:
   G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
     : _ct_bs(ct_bs)
   { }
   virtual bool doHeapRegion(HeapRegion* r)
   {
     MemRegion mr(r->bottom(), r->end());
     if (r->is_survivor()) {
       _ct_bs->verify_dirty_region(mr);
     } else {
       _ct_bs->verify_clean_region(mr);
     }
     return false;
   }
 };
 #endif
 void G1CollectedHeap::cleanUpCardTable() {
   CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
   double start = os::elapsedTime();
   // Iterate over the dirty cards region list.
   G1ParCleanupCTTask cleanup_task(ct_bs, this,
                                   _young_list->first_survivor_region());
   if (ParallelGCThreads > 0) {
     set_par_threads(workers()->total_workers());
     workers()->run_task(&cleanup_task);
     set_par_threads(0);
   } else {
     while (_dirty_cards_region_list) {
       HeapRegion* r = _dirty_cards_region_list;
       cleanup_task.clear_cards(r);
       _dirty_cards_region_list = r->get_next_dirty_cards_region();
       if (_dirty_cards_region_list == r) {
         // The last region.
         _dirty_cards_region_list = NULL;
       }
       r->set_next_dirty_cards_region(NULL);
     }
     // now, redirty the cards of the survivor regions
     // (it seemed faster to do it this way, instead of iterating over
     // all regions and then clearing / dirtying as appropriate)
     dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
   }
   double elapsed = os::elapsedTime() - start;
   g1_policy()->record_clear_ct_time( elapsed * 1000.0);
 #ifndef PRODUCT
   if (G1VerifyCTCleanup || VerifyAfterGC) {
     G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
     heap_region_iterate(&cleanup_verifier);
   }
 #endif
 }
 void G1CollectedHeap::do_collection_pause_if_appropriate(size_t word_size) {
   if (g1_policy()->should_do_collection_pause(word_size)) {
     do_collection_pause();
   }
 }
 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
   double young_time_ms     = 0.0;
   double non_young_time_ms = 0.0;
   // Since the collection set is a superset of the the young list,
   // all we need to do to clear the young list is clear its
   // head and length, and unlink any young regions in the code below
   _young_list->clear();
   G1CollectorPolicy* policy = g1_policy();
   double start_sec = os::elapsedTime();
   bool non_young = true;
   HeapRegion* cur = cs_head;
   int age_bound = -1;
   size_t rs_lengths = 0;
   while (cur != NULL) {
     if (non_young) {
       if (cur->is_young()) {
         double end_sec = os::elapsedTime();
         double elapsed_ms = (end_sec - start_sec) * 1000.0;
         non_young_time_ms += elapsed_ms;
         start_sec = os::elapsedTime();
         non_young = false;
       }
     } else {
       if (!cur->is_on_free_list()) {
         double end_sec = os::elapsedTime();
         double elapsed_ms = (end_sec - start_sec) * 1000.0;
         young_time_ms += elapsed_ms;
         start_sec = os::elapsedTime();
         non_young = true;
       }
     }
     rs_lengths += cur->rem_set()->occupied();
     HeapRegion* next = cur->next_in_collection_set();
     assert(cur->in_collection_set(), "bad CS");
     cur->set_next_in_collection_set(NULL);
     cur->set_in_collection_set(false);
     if (cur->is_young()) {
       int index = cur->young_index_in_cset();
       guarantee( index != -1, "invariant" );
       guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
       size_t words_survived = _surviving_young_words[index];
       cur->record_surv_words_in_group(words_survived);
       // At this point the we have 'popped' cur from the collection set
       // (linked via next_in_collection_set()) but it is still in the
       // young list (linked via next_young_region()). Clear the
       // _next_young_region field.
       cur->set_next_young_region(NULL);
     } else {
       int index = cur->young_index_in_cset();
       guarantee( index == -1, "invariant" );
     }
     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
             (!cur->is_young() && cur->young_index_in_cset() == -1),
             "invariant" );
     if (!cur->evacuation_failed()) {
       // And the region is empty.
       assert(!cur->is_empty(),
              "Should not have empty regions in a CS.");
       free_region(cur);
     } else {
       cur->uninstall_surv_rate_group();
       if (cur->is_young())
         cur->set_young_index_in_cset(-1);
       cur->set_not_young();
       cur->set_evacuation_failed(false);
     }
     cur = next;
   }
   policy->record_max_rs_lengths(rs_lengths);
   policy->cset_regions_freed();
   double end_sec = os::elapsedTime();
   double elapsed_ms = (end_sec - start_sec) * 1000.0;
   if (non_young)
     non_young_time_ms += elapsed_ms;
   else
     young_time_ms += elapsed_ms;
   policy->record_young_free_cset_time_ms(young_time_ms);
   policy->record_non_young_free_cset_time_ms(non_young_time_ms);
 }
 // This routine is similar to the above but does not record
 // any policy statistics or update free lists; we are abandoning
 // the current incremental collection set in preparation of a
 // full collection. After the full GC we will start to build up
 // the incremental collection set again.
 // This is only called when we're doing a full collection
 // and is immediately followed by the tearing down of the young list.
 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
   HeapRegion* cur = cs_head;
   while (cur != NULL) {
     HeapRegion* next = cur->next_in_collection_set();
     assert(cur->in_collection_set(), "bad CS");
     cur->set_next_in_collection_set(NULL);
     cur->set_in_collection_set(false);
     cur->set_young_index_in_cset(-1);
     cur = next;
   }
 }
 HeapRegion*
 G1CollectedHeap::alloc_region_from_unclean_list_locked(bool zero_filled) {
   assert(ZF_mon->owned_by_self(), "Precondition");
   HeapRegion* res = pop_unclean_region_list_locked();
   if (res != NULL) {
     assert(!res->continuesHumongous() &&
            res->zero_fill_state() != HeapRegion::Allocated,
            "Only free regions on unclean list.");
     if (zero_filled) {
       res->ensure_zero_filled_locked();
       res->set_zero_fill_allocated();
     }
   }
   return res;
 }
 HeapRegion* G1CollectedHeap::alloc_region_from_unclean_list(bool zero_filled) {
   MutexLockerEx zx(ZF_mon, Mutex::_no_safepoint_check_flag);
   return alloc_region_from_unclean_list_locked(zero_filled);
 }
 void G1CollectedHeap::put_region_on_unclean_list(HeapRegion* r) {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   put_region_on_unclean_list_locked(r);
   if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
 }
 void G1CollectedHeap::set_unclean_regions_coming(bool b) {
   MutexLockerEx x(Cleanup_mon);
   set_unclean_regions_coming_locked(b);
 }
 void G1CollectedHeap::set_unclean_regions_coming_locked(bool b) {
   assert(Cleanup_mon->owned_by_self(), "Precondition");
   _unclean_regions_coming = b;
   // Wake up mutator threads that might be waiting for completeCleanup to
   // finish.
   if (!b) Cleanup_mon->notify_all();
 }
 void G1CollectedHeap::wait_for_cleanup_complete() {
   MutexLockerEx x(Cleanup_mon);
   wait_for_cleanup_complete_locked();
 }
 void G1CollectedHeap::wait_for_cleanup_complete_locked() {
   assert(Cleanup_mon->owned_by_self(), "precondition");
   while (_unclean_regions_coming) {
     Cleanup_mon->wait();
   }
 }
 void
 G1CollectedHeap::put_region_on_unclean_list_locked(HeapRegion* r) {
   assert(ZF_mon->owned_by_self(), "precondition.");
 #ifdef ASSERT
   if (r->is_gc_alloc_region()) {
     ResourceMark rm;
     stringStream region_str;
     print_on(&region_str);
     assert(!r->is_gc_alloc_region(), err_msg("Unexpected GC allocation region: %s",
                                              region_str.as_string()));
   }
 #endif
   _unclean_region_list.insert_before_head(r);
 }
 void
 G1CollectedHeap::prepend_region_list_on_unclean_list(UncleanRegionList* list) {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   prepend_region_list_on_unclean_list_locked(list);
   if (should_zf()) ZF_mon->notify_all(); // Wake up ZF thread.
 }
 void
 G1CollectedHeap::
 prepend_region_list_on_unclean_list_locked(UncleanRegionList* list) {
   assert(ZF_mon->owned_by_self(), "precondition.");
   _unclean_region_list.prepend_list(list);
 }
 HeapRegion* G1CollectedHeap::pop_unclean_region_list_locked() {
   assert(ZF_mon->owned_by_self(), "precondition.");
   HeapRegion* res = _unclean_region_list.pop();
   if (res != NULL) {
     // Inform ZF thread that there's a new unclean head.
     if (_unclean_region_list.hd() != NULL && should_zf())
       ZF_mon->notify_all();
   }
   return res;
 }
 HeapRegion* G1CollectedHeap::peek_unclean_region_list_locked() {
   assert(ZF_mon->owned_by_self(), "precondition.");
   return _unclean_region_list.hd();
 }
 bool G1CollectedHeap::move_cleaned_region_to_free_list_locked() {
   assert(ZF_mon->owned_by_self(), "Precondition");
   HeapRegion* r = peek_unclean_region_list_locked();
   if (r != NULL && r->zero_fill_state() == HeapRegion::ZeroFilled) {
     // Result of below must be equal to "r", since we hold the lock.
     (void)pop_unclean_region_list_locked();
     put_free_region_on_list_locked(r);
     return true;
   } else {
     return false;
   }
 }
 bool G1CollectedHeap::move_cleaned_region_to_free_list() {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   return move_cleaned_region_to_free_list_locked();
 }
 void G1CollectedHeap::put_free_region_on_list_locked(HeapRegion* r) {
   assert(ZF_mon->owned_by_self(), "precondition.");
   assert(_free_region_list_size == free_region_list_length(), "Inv");
   assert(r->zero_fill_state() == HeapRegion::ZeroFilled,
         "Regions on free list must be zero filled");
   assert(!r->isHumongous(), "Must not be humongous.");
   assert(r->is_empty(), "Better be empty");
   assert(!r->is_on_free_list(),
          "Better not already be on free list");
   assert(!r->is_on_unclean_list(),
          "Better not already be on unclean list");
   r->set_on_free_list(true);
   r->set_next_on_free_list(_free_region_list);
   _free_region_list = r;
   _free_region_list_size++;
   assert(_free_region_list_size == free_region_list_length(), "Inv");
 }
 void G1CollectedHeap::put_free_region_on_list(HeapRegion* r) {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   put_free_region_on_list_locked(r);
 }
 HeapRegion* G1CollectedHeap::pop_free_region_list_locked() {
   assert(ZF_mon->owned_by_self(), "precondition.");
   assert(_free_region_list_size == free_region_list_length(), "Inv");
   HeapRegion* res = _free_region_list;
   if (res != NULL) {
     _free_region_list = res->next_from_free_list();
     _free_region_list_size--;
     res->set_on_free_list(false);
     res->set_next_on_free_list(NULL);
     assert(_free_region_list_size == free_region_list_length(), "Inv");
   }
   return res;
 }
 HeapRegion* G1CollectedHeap::alloc_free_region_from_lists(bool zero_filled) {
   // By self, or on behalf of self.
   assert(Heap_lock->is_locked(), "Precondition");
   HeapRegion* res = NULL;
   bool first = true;
   while (res == NULL) {
     if (zero_filled || !first) {
       MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
       res = pop_free_region_list_locked();
       if (res != NULL) {
         assert(!res->zero_fill_is_allocated(),
                "No allocated regions on free list.");
         res->set_zero_fill_allocated();
       } else if (!first) {
         break;  // We tried both, time to return NULL.
       }
     }
     if (res == NULL) {
       res = alloc_region_from_unclean_list(zero_filled);
     }
     assert(res == NULL ||
            !zero_filled ||
            res->zero_fill_is_allocated(),
            "We must have allocated the region we're returning");
     first = false;
   }
   return res;
 }
 void G1CollectedHeap::remove_allocated_regions_from_lists() {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   {
     HeapRegion* prev = NULL;
     HeapRegion* cur = _unclean_region_list.hd();
     while (cur != NULL) {
       HeapRegion* next = cur->next_from_unclean_list();
       if (cur->zero_fill_is_allocated()) {
         // Remove from the list.
         if (prev == NULL) {
           (void)_unclean_region_list.pop();
         } else {
           _unclean_region_list.delete_after(prev);
         }
         cur->set_on_unclean_list(false);
         cur->set_next_on_unclean_list(NULL);
       } else {
         prev = cur;
       }
       cur = next;
     }
     assert(_unclean_region_list.sz() == unclean_region_list_length(),
            "Inv");
   }
   {
     HeapRegion* prev = NULL;
     HeapRegion* cur = _free_region_list;
     while (cur != NULL) {
       HeapRegion* next = cur->next_from_free_list();
       if (cur->zero_fill_is_allocated()) {
         // Remove from the list.
         if (prev == NULL) {
           _free_region_list = cur->next_from_free_list();
         } else {
           prev->set_next_on_free_list(cur->next_from_free_list());
         }
         cur->set_on_free_list(false);
         cur->set_next_on_free_list(NULL);
         _free_region_list_size--;
       } else {
         prev = cur;
       }
       cur = next;
     }
     assert(_free_region_list_size == free_region_list_length(), "Inv");
   }
 }
 bool G1CollectedHeap::verify_region_lists() {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   return verify_region_lists_locked();
 }
 bool G1CollectedHeap::verify_region_lists_locked() {
   HeapRegion* unclean = _unclean_region_list.hd();
   while (unclean != NULL) {
     guarantee(unclean->is_on_unclean_list(), "Well, it is!");
     guarantee(!unclean->is_on_free_list(), "Well, it shouldn't be!");
     guarantee(unclean->zero_fill_state() != HeapRegion::Allocated,
               "Everything else is possible.");
     unclean = unclean->next_from_unclean_list();
   }
   guarantee(_unclean_region_list.sz() == unclean_region_list_length(), "Inv");
   HeapRegion* free_r = _free_region_list;
   while (free_r != NULL) {
     assert(free_r->is_on_free_list(), "Well, it is!");
     assert(!free_r->is_on_unclean_list(), "Well, it shouldn't be!");
     switch (free_r->zero_fill_state()) {
     case HeapRegion::NotZeroFilled:
     case HeapRegion::ZeroFilling:
       guarantee(false, "Should not be on free list.");
       break;
     default:
       // Everything else is possible.
       break;
     }
     free_r = free_r->next_from_free_list();
   }
   guarantee(_free_region_list_size == free_region_list_length(), "Inv");
   // If we didn't do an assertion...
   return true;
 }
 size_t G1CollectedHeap::free_region_list_length() {
   assert(ZF_mon->owned_by_self(), "precondition.");
   size_t len = 0;
   HeapRegion* cur = _free_region_list;
   while (cur != NULL) {
     len++;
     cur = cur->next_from_free_list();
   }
   return len;
 }
 size_t G1CollectedHeap::unclean_region_list_length() {
   assert(ZF_mon->owned_by_self(), "precondition.");
   return _unclean_region_list.length();
 }
 size_t G1CollectedHeap::n_regions() {
   return _hrs->length();
 }
 size_t G1CollectedHeap::max_regions() {
   return
     (size_t)align_size_up(g1_reserved_obj_bytes(), HeapRegion::GrainBytes) /
     HeapRegion::GrainBytes;
 }
 size_t G1CollectedHeap::free_regions() {
   /* Possibly-expensive assert.
   assert(_free_regions == count_free_regions(),
          "_free_regions is off.");
   */
   return _free_regions;
 }
 bool G1CollectedHeap::should_zf() {
   return _free_region_list_size < (size_t) G1ConcZFMaxRegions;
 }
 class RegionCounter: public HeapRegionClosure {
   size_t _n;
 public:
   RegionCounter() : _n(0) {}
   bool doHeapRegion(HeapRegion* r) {
     if (r->is_empty()) {
       assert(!r->isHumongous(), "H regions should not be empty.");
       _n++;
     }
     return false;
   }
   int res() { return (int) _n; }
 };
 size_t G1CollectedHeap::count_free_regions() {
   RegionCounter rc;
   heap_region_iterate(&rc);
   size_t n = rc.res();
   if (_cur_alloc_region != NULL && _cur_alloc_region->is_empty())
     n--;
   return n;
 }
 size_t G1CollectedHeap::count_free_regions_list() {
   size_t n = 0;
   size_t o = 0;
   ZF_mon->lock_without_safepoint_check();
   HeapRegion* cur = _free_region_list;
   while (cur != NULL) {
     cur = cur->next_from_free_list();
     n++;
   }
   size_t m = unclean_region_list_length();
   ZF_mon->unlock();
   return n + m;
 }
 bool G1CollectedHeap::should_set_young_locked() {
   assert(heap_lock_held_for_gc(),
               "the heap lock should already be held by or for this thread");
   return  (g1_policy()->in_young_gc_mode() &&
            g1_policy()->should_add_next_region_to_young_list());
 }
 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
   assert(heap_lock_held_for_gc(),
               "the heap lock should already be held by or for this thread");
   _young_list->push_region(hr);
   g1_policy()->set_region_short_lived(hr);
 }
 class NoYoungRegionsClosure: public HeapRegionClosure {
 private:
   bool _success;
 public:
   NoYoungRegionsClosure() : _success(true) { }
   bool doHeapRegion(HeapRegion* r) {
     if (r->is_young()) {
       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
                              r->bottom(), r->end());
       _success = false;
     }
     return false;
   }
   bool success() { return _success; }
 };
 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
   bool ret = _young_list->check_list_empty(check_sample);
   if (check_heap) {
     NoYoungRegionsClosure closure;
     heap_region_iterate(&closure);
     ret = ret && closure.success();
   }
   return ret;
 }
 void G1CollectedHeap::empty_young_list() {
   assert(heap_lock_held_for_gc(),
               "the heap lock should already be held by or for this thread");
   assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
   _young_list->empty_list();
 }
 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
   bool no_allocs = true;
   for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
     HeapRegion* r = _gc_alloc_regions[ap];
     no_allocs = r == NULL || r->saved_mark_at_top();
   }
   return no_allocs;
 }
 void G1CollectedHeap::retire_all_alloc_regions() {
   for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
     HeapRegion* r = _gc_alloc_regions[ap];
     if (r != NULL) {
       // Check for aliases.
       bool has_processed_alias = false;
       for (int i = 0; i < ap; ++i) {
         if (_gc_alloc_regions[i] == r) {
           has_processed_alias = true;
           break;
         }
       }
       if (!has_processed_alias) {
         retire_alloc_region(r, false /* par */);
       }
     }
   }
 }
 // Done at the start of full GC.
 void G1CollectedHeap::tear_down_region_lists() {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   while (pop_unclean_region_list_locked() != NULL) ;
   assert(_unclean_region_list.hd() == NULL && _unclean_region_list.sz() == 0,
          "Postconditions of loop.");
   while (pop_free_region_list_locked() != NULL) ;
   assert(_free_region_list == NULL, "Postcondition of loop.");
   if (_free_region_list_size != 0) {
     gclog_or_tty->print_cr("Size is %d.", _free_region_list_size);
     print_on(gclog_or_tty, true /* extended */);
   }
   assert(_free_region_list_size == 0, "Postconditions of loop.");
 }
 class RegionResetter: public HeapRegionClosure {
   G1CollectedHeap* _g1;
   int _n;
 public:
   RegionResetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
   bool doHeapRegion(HeapRegion* r) {
     if (r->continuesHumongous()) return false;
     if (r->top() > r->bottom()) {
       if (r->top() < r->end()) {
         Copy::fill_to_words(r->top(),
                           pointer_delta(r->end(), r->top()));
       }
       r->set_zero_fill_allocated();
     } else {
       assert(r->is_empty(), "tautology");
       _n++;
       switch (r->zero_fill_state()) {
         case HeapRegion::NotZeroFilled:
         case HeapRegion::ZeroFilling:
           _g1->put_region_on_unclean_list_locked(r);
           break;
         case HeapRegion::Allocated:
           r->set_zero_fill_complete();
           // no break; go on to put on free list.
         case HeapRegion::ZeroFilled:
           _g1->put_free_region_on_list_locked(r);
           break;
       }
     }
     return false;
   }
   int getFreeRegionCount() {return _n;}
 };
 // Done at the end of full GC.
 void G1CollectedHeap::rebuild_region_lists() {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   // This needs to go at the end of the full GC.
   RegionResetter rs;
   heap_region_iterate(&rs);
   _free_regions = rs.getFreeRegionCount();
   // Tell the ZF thread it may have work to do.
   if (should_zf()) ZF_mon->notify_all();
 }
 class UsedRegionsNeedZeroFillSetter: public HeapRegionClosure {
   G1CollectedHeap* _g1;
   int _n;
 public:
   UsedRegionsNeedZeroFillSetter() : _g1(G1CollectedHeap::heap()), _n(0) {}
   bool doHeapRegion(HeapRegion* r) {
     if (r->continuesHumongous()) return false;
     if (r->top() > r->bottom()) {
       // There are assertions in "set_zero_fill_needed()" below that
       // require top() == bottom(), so this is technically illegal.
       // We'll skirt the law here, by making that true temporarily.
       DEBUG_ONLY(HeapWord* save_top = r->top();
                  r->set_top(r->bottom()));
       r->set_zero_fill_needed();
       DEBUG_ONLY(r->set_top(save_top));
     }
     return false;
   }
 };
 // Done at the start of full GC.
 void G1CollectedHeap::set_used_regions_to_need_zero_fill() {
   MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
   // This needs to go at the end of the full GC.
   UsedRegionsNeedZeroFillSetter rs;
   heap_region_iterate(&rs);
 }
 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
   _refine_cte_cl->set_concurrent(concurrent);
 }
 #ifndef PRODUCT
 class PrintHeapRegionClosure: public HeapRegionClosure {
 public:
   bool doHeapRegion(HeapRegion *r) {
     gclog_or_tty->print("Region: "PTR_FORMAT":", r);
     if (r != NULL) {
       if (r->is_on_free_list())
         gclog_or_tty->print("Free ");
       if (r->is_young())
         gclog_or_tty->print("Young ");
       if (r->isHumongous())
         gclog_or_tty->print("Is Humongous ");
       r->print();
     }
     return false;
   }
 };
 class SortHeapRegionClosure : public HeapRegionClosure {
   size_t young_regions,free_regions, unclean_regions;
   size_t hum_regions, count;
   size_t unaccounted, cur_unclean, cur_alloc;
   size_t total_free;
   HeapRegion* cur;
 public:
   SortHeapRegionClosure(HeapRegion *_cur) : cur(_cur), young_regions(0),
     free_regions(0), unclean_regions(0),
     hum_regions(0),
     count(0), unaccounted(0),
     cur_alloc(0), total_free(0)
   {}
   bool doHeapRegion(HeapRegion *r) {
     count++;
     if (r->is_on_free_list()) free_regions++;
     else if (r->is_on_unclean_list()) unclean_regions++;
     else if (r->isHumongous())  hum_regions++;
     else if (r->is_young()) young_regions++;
     else if (r == cur) cur_alloc++;
     else unaccounted++;
     return false;
   }
   void print() {
     total_free = free_regions + unclean_regions;
     gclog_or_tty->print("%d regions\n", count);
     gclog_or_tty->print("%d free: free_list = %d unclean = %d\n",
                         total_free, free_regions, unclean_regions);
     gclog_or_tty->print("%d humongous %d young\n",
                         hum_regions, young_regions);
     gclog_or_tty->print("%d cur_alloc\n", cur_alloc);
     gclog_or_tty->print("UHOH unaccounted = %d\n", unaccounted);
   }
 };
 void G1CollectedHeap::print_region_counts() {
   SortHeapRegionClosure sc(_cur_alloc_region);
   PrintHeapRegionClosure cl;
   heap_region_iterate(&cl);
   heap_region_iterate(&sc);
   sc.print();
   print_region_accounting_info();
 };
 bool G1CollectedHeap::regions_accounted_for() {
   // TODO: regions accounting for young/survivor/tenured
   return true;
 }
 bool G1CollectedHeap::print_region_accounting_info() {
   gclog_or_tty->print_cr("Free regions: %d (count: %d count list %d) (clean: %d unclean: %d).",
                          free_regions(),
                          count_free_regions(), count_free_regions_list(),
                          _free_region_list_size, _unclean_region_list.sz());
   gclog_or_tty->print_cr("cur_alloc: %d.",
                          (_cur_alloc_region == NULL ? 0 : 1));
   gclog_or_tty->print_cr("H regions: %d.", _num_humongous_regions);
   // TODO: check regions accounting for young/survivor/tenured
   return true;
 }
 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
   HeapRegion* hr = heap_region_containing(p);
   if (hr == NULL) {
     return is_in_permanent(p);
   } else {
     return hr->is_in(p);
   }
 }
 #endif // !PRODUCT
 void G1CollectedHeap::g1_unimplemented() {
   // Unimplemented();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp@5f429ee79634 (annotated)

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp