Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2005-2008 Sun Microsystems, Inc.  All Rights Reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 #include "incls/_precompiled.incl"

 #include "incls/_psParallelCompact.cpp.incl"

 #include <math.h>

 // All sizes are in HeapWords.

 const size_t ParallelCompactData::Log2ChunkSize  = 9; // 512 words

 const size_t ParallelCompactData::ChunkSize      = (size_t)1 << Log2ChunkSize;

 const size_t ParallelCompactData::ChunkSizeBytes = ChunkSize << LogHeapWordSize;

 const size_t ParallelCompactData::ChunkSizeOffsetMask = ChunkSize - 1;

 const size_t ParallelCompactData::ChunkAddrOffsetMask = ChunkSizeBytes - 1;

 const size_t ParallelCompactData::ChunkAddrMask  = ~ChunkAddrOffsetMask;

 // 32-bit:  128 words covers 4 bitmap words

 // 64-bit:  128 words covers 2 bitmap words

 const size_t ParallelCompactData::Log2BlockSize   = 7; // 128 words

 const size_t ParallelCompactData::BlockSize       = (size_t)1 << Log2BlockSize;

 const size_t ParallelCompactData::BlockOffsetMask = BlockSize - 1;

 const size_t ParallelCompactData::BlockMask       = ~BlockOffsetMask;

 const size_t ParallelCompactData::BlocksPerChunk = ChunkSize / BlockSize;

 const ParallelCompactData::ChunkData::chunk_sz_t

 ParallelCompactData::ChunkData::dc_shift = 27;

 const ParallelCompactData::ChunkData::chunk_sz_t

 ParallelCompactData::ChunkData::dc_mask = ~0U << dc_shift;

 const ParallelCompactData::ChunkData::chunk_sz_t

 ParallelCompactData::ChunkData::dc_one = 0x1U << dc_shift;

 const ParallelCompactData::ChunkData::chunk_sz_t

 ParallelCompactData::ChunkData::los_mask = ~dc_mask;

 const ParallelCompactData::ChunkData::chunk_sz_t

 ParallelCompactData::ChunkData::dc_claimed = 0x8U << dc_shift;

 const ParallelCompactData::ChunkData::chunk_sz_t

 ParallelCompactData::ChunkData::dc_completed = 0xcU << dc_shift;

 #ifdef ASSERT

 short   ParallelCompactData::BlockData::_cur_phase = 0;

 #endif

 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];

 bool      PSParallelCompact::_print_phases = false;

 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;

 klassOop            PSParallelCompact::_updated_int_array_klass_obj = NULL;

 double PSParallelCompact::_dwl_mean;

 double PSParallelCompact::_dwl_std_dev;

 double PSParallelCompact::_dwl_first_term;

 double PSParallelCompact::_dwl_adjustment;

 #ifdef  ASSERT

 bool   PSParallelCompact::_dwl_initialized = false;

 #endif  // #ifdef ASSERT

 #ifdef VALIDATE_MARK_SWEEP

 GrowableArray<void*>*   PSParallelCompact::_root_refs_stack = NULL;

 GrowableArray<oop> *    PSParallelCompact::_live_oops = NULL;

 GrowableArray<oop> *    PSParallelCompact::_live_oops_moved_to = NULL;

 GrowableArray<size_t>*  PSParallelCompact::_live_oops_size = NULL;

 size_t                  PSParallelCompact::_live_oops_index = 0;

 size_t                  PSParallelCompact::_live_oops_index_at_perm = 0;

 GrowableArray<void*>*   PSParallelCompact::_other_refs_stack = NULL;

 GrowableArray<void*>*   PSParallelCompact::_adjusted_pointers = NULL;

 bool                    PSParallelCompact::_pointer_tracking = false;

 bool                    PSParallelCompact::_root_tracking = true;

 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL;

 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL;

 GrowableArray<size_t>   * PSParallelCompact::_cur_gc_live_oops_size = NULL;

 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL;

 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL;

 GrowableArray<size_t>   * PSParallelCompact::_last_gc_live_oops_size = NULL;

 #endif

 #ifndef PRODUCT

 const char* PSParallelCompact::space_names[] = {

   "perm", "old ", "eden", "from", "to  "

 };

 void PSParallelCompact::print_chunk_ranges()

 {

   tty->print_cr("space  bottom     top        end        new_top");

   tty->print_cr("------ ---------- ---------- ---------- ----------");

   for (unsigned int id = 0; id < last_space_id; ++id) {

     const MutableSpace* space = _space_info[id].space();

     tty->print_cr("%u %s "

                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "

                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",

                   id, space_names[id],

                   summary_data().addr_to_chunk_idx(space->bottom()),

                   summary_data().addr_to_chunk_idx(space->top()),

                   summary_data().addr_to_chunk_idx(space->end()),

                   summary_data().addr_to_chunk_idx(_space_info[id].new_top()));

   }

 }

 void

 print_generic_summary_chunk(size_t i, const ParallelCompactData::ChunkData* c)

 {

 #define CHUNK_IDX_FORMAT        SIZE_FORMAT_W(7)

 #define CHUNK_DATA_FORMAT       SIZE_FORMAT_W(5)

   ParallelCompactData& sd = PSParallelCompact::summary_data();

   size_t dci = c->destination() ? sd.addr_to_chunk_idx(c->destination()) : 0;

   tty->print_cr(CHUNK_IDX_FORMAT " " PTR_FORMAT " "

                 CHUNK_IDX_FORMAT " " PTR_FORMAT " "

                 CHUNK_DATA_FORMAT " " CHUNK_DATA_FORMAT " "

                 CHUNK_DATA_FORMAT " " CHUNK_IDX_FORMAT " %d",

                 i, c->data_location(), dci, c->destination(),

                 c->partial_obj_size(), c->live_obj_size(),

                 c->data_size(), c->source_chunk(), c->destination_count());

 #undef  CHUNK_IDX_FORMAT

 #undef  CHUNK_DATA_FORMAT

 }

 void

 print_generic_summary_data(ParallelCompactData& summary_data,

                            HeapWord* const beg_addr,

                            HeapWord* const end_addr)

 {

   size_t total_words = 0;

   size_t i = summary_data.addr_to_chunk_idx(beg_addr);

   const size_t last = summary_data.addr_to_chunk_idx(end_addr);

   HeapWord* pdest = 0;

   while (i <= last) {

     ParallelCompactData::ChunkData* c = summary_data.chunk(i);

     if (c->data_size() != 0 || c->destination() != pdest) {

       print_generic_summary_chunk(i, c);

       total_words += c->data_size();

       pdest = c->destination();

     }

     ++i;

   }

   tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);

 }

 void

 print_generic_summary_data(ParallelCompactData& summary_data,

                            SpaceInfo* space_info)

 {

   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {

     const MutableSpace* space = space_info[id].space();

     print_generic_summary_data(summary_data, space->bottom(),

                                MAX2(space->top(), space_info[id].new_top()));

   }

 }

 void

 print_initial_summary_chunk(size_t i,

                             const ParallelCompactData::ChunkData* c,

                             bool newline = true)

 {

   tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "

              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "

              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",

              i, c->destination(),

              c->partial_obj_size(), c->live_obj_size(),

              c->data_size(), c->source_chunk(), c->destination_count());

   if (newline) tty->cr();

 }

 void

 print_initial_summary_data(ParallelCompactData& summary_data,

                            const MutableSpace* space) {

   if (space->top() == space->bottom()) {

     return;

   }

   const size_t chunk_size = ParallelCompactData::ChunkSize;

   HeapWord* const top_aligned_up = summary_data.chunk_align_up(space->top());

   const size_t end_chunk = summary_data.addr_to_chunk_idx(top_aligned_up);

   const ParallelCompactData::ChunkData* c = summary_data.chunk(end_chunk - 1);

   HeapWord* end_addr = c->destination() + c->data_size();

   const size_t live_in_space = pointer_delta(end_addr, space->bottom());

   // Print (and count) the full chunks at the beginning of the space.

   size_t full_chunk_count = 0;

   size_t i = summary_data.addr_to_chunk_idx(space->bottom());

   while (i < end_chunk && summary_data.chunk(i)->data_size() == chunk_size) {

     print_initial_summary_chunk(i, summary_data.chunk(i));

     ++full_chunk_count;

     ++i;

   }

   size_t live_to_right = live_in_space - full_chunk_count * chunk_size;

   double max_reclaimed_ratio = 0.0;

   size_t max_reclaimed_ratio_chunk = 0;

   size_t max_dead_to_right = 0;

   size_t max_live_to_right = 0;

   // Print the 'reclaimed ratio' for chunks while there is something live in the

   // chunk or to the right of it.  The remaining chunks are empty (and

   // uninteresting), and computing the ratio will result in division by 0.

   while (i < end_chunk && live_to_right > 0) {

     c = summary_data.chunk(i);

     HeapWord* const chunk_addr = summary_data.chunk_to_addr(i);

     const size_t used_to_right = pointer_delta(space->top(), chunk_addr);

     const size_t dead_to_right = used_to_right - live_to_right;

     const double reclaimed_ratio = double(dead_to_right) / live_to_right;

     if (reclaimed_ratio > max_reclaimed_ratio) {

             max_reclaimed_ratio = reclaimed_ratio;

             max_reclaimed_ratio_chunk = i;

             max_dead_to_right = dead_to_right;

             max_live_to_right = live_to_right;

     }

     print_initial_summary_chunk(i, c, false);

     tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),

                   reclaimed_ratio, dead_to_right, live_to_right);

     live_to_right -= c->data_size();

     ++i;

   }

   // Any remaining chunks are empty.  Print one more if there is one.

   if (i < end_chunk) {

     print_initial_summary_chunk(i, summary_data.chunk(i));

   }

   tty->print_cr("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "

                 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",

                 max_reclaimed_ratio_chunk, max_dead_to_right,

                 max_live_to_right, max_reclaimed_ratio);

 }

 void

 print_initial_summary_data(ParallelCompactData& summary_data,

                            SpaceInfo* space_info) {

   unsigned int id = PSParallelCompact::perm_space_id;

   const MutableSpace* space;

   do {

     space = space_info[id].space();

     print_initial_summary_data(summary_data, space);

   } while (++id < PSParallelCompact::eden_space_id);

   do {

     space = space_info[id].space();

     print_generic_summary_data(summary_data, space->bottom(), space->top());

   } while (++id < PSParallelCompact::last_space_id);

 }

 #endif  // #ifndef PRODUCT

 #ifdef  ASSERT

 size_t add_obj_count;

 size_t add_obj_size;

 size_t mark_bitmap_count;

 size_t mark_bitmap_size;

 #endif  // #ifdef ASSERT

 ParallelCompactData::ParallelCompactData()

 {

   _region_start = 0;

   _chunk_vspace = 0;

   _chunk_data = 0;

   _chunk_count = 0;

   _block_vspace = 0;

   _block_data = 0;

   _block_count = 0;

 }

 bool ParallelCompactData::initialize(MemRegion covered_region)

 {

   _region_start = covered_region.start();

   const size_t region_size = covered_region.word_size();

   DEBUG_ONLY(_region_end = _region_start + region_size;)

   assert(chunk_align_down(_region_start) == _region_start,

          "region start not aligned");

   assert((region_size & ChunkSizeOffsetMask) == 0,

          "region size not a multiple of ChunkSize");

   bool result = initialize_chunk_data(region_size);

   // Initialize the block data if it will be used for updating pointers, or if

   // this is a debug build.

   if (!UseParallelOldGCChunkPointerCalc || trueInDebug) {

     result = result && initialize_block_data(region_size);

   }

   return result;

 }

 PSVirtualSpace*

 ParallelCompactData::create_vspace(size_t count, size_t element_size)

 {

   const size_t raw_bytes = count * element_size;

   const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);

   const size_t granularity = os::vm_allocation_granularity();

   const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));

   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :

     MAX2(page_sz, granularity);

   ReservedSpace rs(bytes, rs_align, rs_align > 0);

   os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),

                        rs.size());

   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);

   if (vspace != 0) {

     if (vspace->expand_by(bytes)) {

       return vspace;

     }

     delete vspace;

     // Release memory reserved in the space.

     rs.release();

   }

   return 0;

 }

 bool ParallelCompactData::initialize_chunk_data(size_t region_size)

 {

   const size_t count = (region_size + ChunkSizeOffsetMask) >> Log2ChunkSize;

   _chunk_vspace = create_vspace(count, sizeof(ChunkData));

   if (_chunk_vspace != 0) {

     _chunk_data = (ChunkData*)_chunk_vspace->reserved_low_addr();

     _chunk_count = count;

     return true;

   }

   return false;

 }

 bool ParallelCompactData::initialize_block_data(size_t region_size)

 {

   const size_t count = (region_size + BlockOffsetMask) >> Log2BlockSize;

   _block_vspace = create_vspace(count, sizeof(BlockData));

   if (_block_vspace != 0) {

     _block_data = (BlockData*)_block_vspace->reserved_low_addr();

     _block_count = count;

     return true;

   }

   return false;

 }

 void ParallelCompactData::clear()

 {

   if (_block_data) {

     memset(_block_data, 0, _block_vspace->committed_size());

   }

   memset(_chunk_data, 0, _chunk_vspace->committed_size());

 }

 void ParallelCompactData::clear_range(size_t beg_chunk, size_t end_chunk) {

   assert(beg_chunk <= _chunk_count, "beg_chunk out of range");

   assert(end_chunk <= _chunk_count, "end_chunk out of range");

   assert(ChunkSize % BlockSize == 0, "ChunkSize not a multiple of BlockSize");

   const size_t chunk_cnt = end_chunk - beg_chunk;

   if (_block_data) {

     const size_t blocks_per_chunk = ChunkSize / BlockSize;

     const size_t beg_block = beg_chunk * blocks_per_chunk;

     const size_t block_cnt = chunk_cnt * blocks_per_chunk;

     memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));

   }

   memset(_chunk_data + beg_chunk, 0, chunk_cnt * sizeof(ChunkData));

 }

 HeapWord* ParallelCompactData::partial_obj_end(size_t chunk_idx) const

 {

   const ChunkData* cur_cp = chunk(chunk_idx);

   const ChunkData* const end_cp = chunk(chunk_count() - 1);

   HeapWord* result = chunk_to_addr(chunk_idx);

   if (cur_cp < end_cp) {

     do {

       result += cur_cp->partial_obj_size();

     } while (cur_cp->partial_obj_size() == ChunkSize && ++cur_cp < end_cp);

   }

   return result;

 }

 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)

 {

   const size_t obj_ofs = pointer_delta(addr, _region_start);

   const size_t beg_chunk = obj_ofs >> Log2ChunkSize;

   const size_t end_chunk = (obj_ofs + len - 1) >> Log2ChunkSize;

   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)

   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)

   if (beg_chunk == end_chunk) {

     // All in one chunk.

     _chunk_data[beg_chunk].add_live_obj(len);

     return;

   }

   // First chunk.

   const size_t beg_ofs = chunk_offset(addr);

   _chunk_data[beg_chunk].add_live_obj(ChunkSize - beg_ofs);

   klassOop klass = ((oop)addr)->klass();

   // Middle chunks--completely spanned by this object.

   for (size_t chunk = beg_chunk + 1; chunk < end_chunk; ++chunk) {

     _chunk_data[chunk].set_partial_obj_size(ChunkSize);

     _chunk_data[chunk].set_partial_obj_addr(addr);

   }

   // Last chunk.

   const size_t end_ofs = chunk_offset(addr + len - 1);

   _chunk_data[end_chunk].set_partial_obj_size(end_ofs + 1);

   _chunk_data[end_chunk].set_partial_obj_addr(addr);

 }

 void

 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)

 {

   assert(chunk_offset(beg) == 0, "not ChunkSize aligned");

   assert(chunk_offset(end) == 0, "not ChunkSize aligned");

   size_t cur_chunk = addr_to_chunk_idx(beg);

   const size_t end_chunk = addr_to_chunk_idx(end);

   HeapWord* addr = beg;

   while (cur_chunk < end_chunk) {

     _chunk_data[cur_chunk].set_destination(addr);

     _chunk_data[cur_chunk].set_destination_count(0);

     _chunk_data[cur_chunk].set_source_chunk(cur_chunk);

     _chunk_data[cur_chunk].set_data_location(addr);

     // Update live_obj_size so the chunk appears completely full.

     size_t live_size = ChunkSize - _chunk_data[cur_chunk].partial_obj_size();

     _chunk_data[cur_chunk].set_live_obj_size(live_size);

     ++cur_chunk;

     addr += ChunkSize;

   }

 }

 bool ParallelCompactData::summarize(HeapWord* target_beg, HeapWord* target_end,

                                     HeapWord* source_beg, HeapWord* source_end,

                                     HeapWord** target_next,

                                     HeapWord** source_next) {

   // This is too strict.

   // assert(chunk_offset(source_beg) == 0, "not ChunkSize aligned");

   if (TraceParallelOldGCSummaryPhase) {

     tty->print_cr("tb=" PTR_FORMAT " te=" PTR_FORMAT " "

                   "sb=" PTR_FORMAT " se=" PTR_FORMAT " "

                   "tn=" PTR_FORMAT " sn=" PTR_FORMAT,

                   target_beg, target_end,

                   source_beg, source_end,

                   target_next != 0 ? *target_next : (HeapWord*) 0,

                   source_next != 0 ? *source_next : (HeapWord*) 0);

   }

   size_t cur_chunk = addr_to_chunk_idx(source_beg);

   const size_t end_chunk = addr_to_chunk_idx(chunk_align_up(source_end));

   HeapWord *dest_addr = target_beg;

   while (cur_chunk < end_chunk) {

     size_t words = _chunk_data[cur_chunk].data_size();

 #if     1

     assert(pointer_delta(target_end, dest_addr) >= words,

            "source region does not fit into target region");

 #else

     // XXX - need some work on the corner cases here.  If the chunk does not

     // fit, then must either make sure any partial_obj from the chunk fits, or

     // 'undo' the initial part of the partial_obj that is in the previous chunk.

     if (dest_addr + words >= target_end) {

       // Let the caller know where to continue.

       *target_next = dest_addr;

       *source_next = chunk_to_addr(cur_chunk);

       return false;

     }

 #endif  // #if 1

     _chunk_data[cur_chunk].set_destination(dest_addr);

     // Set the destination_count for cur_chunk, and if necessary, update

     // source_chunk for a destination chunk.  The source_chunk field is updated

     // if cur_chunk is the first (left-most) chunk to be copied to a destination

     // chunk.

     //

     // The destination_count calculation is a bit subtle.  A chunk that has data

     // that compacts into itself does not count itself as a destination.  This

     // maintains the invariant that a zero count means the chunk is available

     // and can be claimed and then filled.

     if (words > 0) {

       HeapWord* const last_addr = dest_addr + words - 1;

       const size_t dest_chunk_1 = addr_to_chunk_idx(dest_addr);

       const size_t dest_chunk_2 = addr_to_chunk_idx(last_addr);

 #if     0

       // Initially assume that the destination chunks will be the same and

       // adjust the value below if necessary.  Under this assumption, if

       // cur_chunk == dest_chunk_2, then cur_chunk will be compacted completely

       // into itself.

       uint destination_count = cur_chunk == dest_chunk_2 ? 0 : 1;

       if (dest_chunk_1 != dest_chunk_2) {

         // Destination chunks differ; adjust destination_count.

         destination_count += 1;

         // Data from cur_chunk will be copied to the start of dest_chunk_2.

         _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk);

       } else if (chunk_offset(dest_addr) == 0) {

         // Data from cur_chunk will be copied to the start of the destination

         // chunk.

         _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk);

       }

 #else

       // Initially assume that the destination chunks will be different and

       // adjust the value below if necessary.  Under this assumption, if

       // cur_chunk == dest_chunk2, then cur_chunk will be compacted partially

       // into dest_chunk_1 and partially into itself.

       uint destination_count = cur_chunk == dest_chunk_2 ? 1 : 2;

       if (dest_chunk_1 != dest_chunk_2) {

         // Data from cur_chunk will be copied to the start of dest_chunk_2.

         _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk);

       } else {

         // Destination chunks are the same; adjust destination_count.

         destination_count -= 1;

         if (chunk_offset(dest_addr) == 0) {

           // Data from cur_chunk will be copied to the start of the destination

           // chunk.

           _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk);

         }

       }

 #endif  // #if 0

       _chunk_data[cur_chunk].set_destination_count(destination_count);

       _chunk_data[cur_chunk].set_data_location(chunk_to_addr(cur_chunk));

       dest_addr += words;

     }

     ++cur_chunk;

   }

   *target_next = dest_addr;

   return true;

 }

 bool ParallelCompactData::partial_obj_ends_in_block(size_t block_index) {

   HeapWord* block_addr = block_to_addr(block_index);

   HeapWord* block_end_addr = block_addr + BlockSize;

   size_t chunk_index = addr_to_chunk_idx(block_addr);

   HeapWord* partial_obj_end_addr = partial_obj_end(chunk_index);

   // An object that ends at the end of the block, ends

   // in the block (the last word of the object is to

   // the left of the end).

   if ((block_addr < partial_obj_end_addr) &&

       (partial_obj_end_addr <= block_end_addr)) {

     return true;

   }

   return false;

 }

 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {

   HeapWord* result = NULL;

   if (UseParallelOldGCChunkPointerCalc) {

     result = chunk_calc_new_pointer(addr);

   } else {

     result = block_calc_new_pointer(addr);

   }

   return result;

 }

 // This method is overly complicated (expensive) to be called

 // for every reference.

 // Try to restructure this so that a NULL is returned if

 // the object is dead.  But don't wast the cycles to explicitly check

 // that it is dead since only live objects should be passed in.

 HeapWord* ParallelCompactData::chunk_calc_new_pointer(HeapWord* addr) {

   assert(addr != NULL, "Should detect NULL oop earlier");

   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");

 #ifdef ASSERT

   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {

     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);

   }

 #endif

   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");

   // Chunk covering the object.

   size_t chunk_index = addr_to_chunk_idx(addr);

   const ChunkData* const chunk_ptr = chunk(chunk_index);

   HeapWord* const chunk_addr = chunk_align_down(addr);

   assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object");

   assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check");

   HeapWord* result = chunk_ptr->destination();

   // If all the data in the chunk is live, then the new location of the object

   // can be calculated from the destination of the chunk plus the offset of the

   // object in the chunk.

   if (chunk_ptr->data_size() == ChunkSize) {

     result += pointer_delta(addr, chunk_addr);

     return result;

   }

   // The new location of the object is

   //    chunk destination +

   //    size of the partial object extending onto the chunk +

   //    sizes of the live objects in the Chunk that are to the left of addr

   const size_t partial_obj_size = chunk_ptr->partial_obj_size();

   HeapWord* const search_start = chunk_addr + partial_obj_size;

   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();

   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));

   result += partial_obj_size + live_to_left;

   assert(result <= addr, "object cannot move to the right");

   return result;

 }

 HeapWord* ParallelCompactData::block_calc_new_pointer(HeapWord* addr) {

   assert(addr != NULL, "Should detect NULL oop earlier");

   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");

 #ifdef ASSERT

   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {

     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);

   }

 #endif

   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");

   // Chunk covering the object.

   size_t chunk_index = addr_to_chunk_idx(addr);

   const ChunkData* const chunk_ptr = chunk(chunk_index);

   HeapWord* const chunk_addr = chunk_align_down(addr);

   assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object");

   assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check");

   HeapWord* result = chunk_ptr->destination();

   // If all the data in the chunk is live, then the new location of the object

   // can be calculated from the destination of the chunk plus the offset of the

   // object in the chunk.

   if (chunk_ptr->data_size() == ChunkSize) {

     result += pointer_delta(addr, chunk_addr);

     return result;

   }

   // The new location of the object is

   //    chunk destination +

   //    block offset +

   //    sizes of the live objects in the Block that are to the left of addr

   const size_t block_offset = addr_to_block_ptr(addr)->offset();

   HeapWord* const search_start = chunk_addr + block_offset;

   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();

   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));

   result += block_offset + live_to_left;

   assert(result <= addr, "object cannot move to the right");

   assert(result == chunk_calc_new_pointer(addr), "Should match");

   return result;

 }

 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {

   klassOop updated_klass;

   if (PSParallelCompact::should_update_klass(old_klass)) {

     updated_klass = (klassOop) calc_new_pointer(old_klass);

   } else {

     updated_klass = old_klass;

   }

   return updated_klass;

 }

 #ifdef  ASSERT

 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)

 {

   const size_t* const beg = (const size_t*)vspace->committed_low_addr();

   const size_t* const end = (const size_t*)vspace->committed_high_addr();

   for (const size_t* p = beg; p < end; ++p) {

     assert(*p == 0, "not zero");

   }

 }

 void ParallelCompactData::verify_clear()

 {

   verify_clear(_chunk_vspace);

   verify_clear(_block_vspace);

 }

 #endif  // #ifdef ASSERT

 #ifdef NOT_PRODUCT

 ParallelCompactData::ChunkData* debug_chunk(size_t chunk_index) {

   ParallelCompactData& sd = PSParallelCompact::summary_data();

   return sd.chunk(chunk_index);

 }

 #endif

 elapsedTimer        PSParallelCompact::_accumulated_time;

 unsigned int        PSParallelCompact::_total_invocations = 0;

 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;

 jlong               PSParallelCompact::_time_of_last_gc = 0;

 CollectorCounters*  PSParallelCompact::_counters = NULL;

 ParMarkBitMap       PSParallelCompact::_mark_bitmap;

 ParallelCompactData PSParallelCompact::_summary_data;

 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;

 void PSParallelCompact::IsAliveClosure::do_object(oop p)   { ShouldNotReachHere(); }

 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }

 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p)       { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }

 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }

 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);

 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);

 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p)       { adjust_pointer(p, _is_root); }

 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }

 void PSParallelCompact::FollowStackClosure::do_void() { follow_stack(_compaction_manager); }

 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p)       { mark_and_push(_compaction_manager, p); }

 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }

 void PSParallelCompact::post_initialize() {

   ParallelScavengeHeap* heap = gc_heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   MemRegion mr = heap->reserved_region();

   _ref_processor = ReferenceProcessor::create_ref_processor(

     mr,                         // span

     true,                       // atomic_discovery

     true,                       // mt_discovery

     &_is_alive_closure,

     ParallelGCThreads,

     ParallelRefProcEnabled);

   _counters = new CollectorCounters("PSParallelCompact", 1);

   // Initialize static fields in ParCompactionManager.

   ParCompactionManager::initialize(mark_bitmap());

 }

 bool PSParallelCompact::initialize() {

   ParallelScavengeHeap* heap = gc_heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   MemRegion mr = heap->reserved_region();

   // Was the old gen get allocated successfully?

   if (!heap->old_gen()->is_allocated()) {

     return false;

   }

   initialize_space_info();

   initialize_dead_wood_limiter();

   if (!_mark_bitmap.initialize(mr)) {

     vm_shutdown_during_initialization("Unable to allocate bit map for "

       "parallel garbage collection for the requested heap size.");

     return false;

   }

   if (!_summary_data.initialize(mr)) {

     vm_shutdown_during_initialization("Unable to allocate tables for "

       "parallel garbage collection for the requested heap size.");

     return false;

   }

   return true;

 }

 void PSParallelCompact::initialize_space_info()

 {

   memset(&_space_info, 0, sizeof(_space_info));

   ParallelScavengeHeap* heap = gc_heap();

   PSYoungGen* young_gen = heap->young_gen();

   MutableSpace* perm_space = heap->perm_gen()->object_space();

   _space_info[perm_space_id].set_space(perm_space);

   _space_info[old_space_id].set_space(heap->old_gen()->object_space());

   _space_info[eden_space_id].set_space(young_gen->eden_space());

   _space_info[from_space_id].set_space(young_gen->from_space());

   _space_info[to_space_id].set_space(young_gen->to_space());

   _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());

   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());

   _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());

   if (TraceParallelOldGCDensePrefix) {

     tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,

                   _space_info[perm_space_id].min_dense_prefix());

   }

 }

 void PSParallelCompact::initialize_dead_wood_limiter()

 {

   const size_t max = 100;

   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;

   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;

   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);

   DEBUG_ONLY(_dwl_initialized = true;)

   _dwl_adjustment = normal_distribution(1.0);

 }

 // Simple class for storing info about the heap at the start of GC, to be used

 // after GC for comparison/printing.

 class PreGCValues {

 public:

   PreGCValues() { }

   PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }

   void fill(ParallelScavengeHeap* heap) {

     _heap_used      = heap->used();

     _young_gen_used = heap->young_gen()->used_in_bytes();

     _old_gen_used   = heap->old_gen()->used_in_bytes();

     _perm_gen_used  = heap->perm_gen()->used_in_bytes();

   };

   size_t heap_used() const      { return _heap_used; }

   size_t young_gen_used() const { return _young_gen_used; }

   size_t old_gen_used() const   { return _old_gen_used; }

   size_t perm_gen_used() const  { return _perm_gen_used; }

 private:

   size_t _heap_used;

   size_t _young_gen_used;

   size_t _old_gen_used;

   size_t _perm_gen_used;

 };

 void

 PSParallelCompact::clear_data_covering_space(SpaceId id)

 {

   // At this point, top is the value before GC, new_top() is the value that will

   // be set at the end of GC.  The marking bitmap is cleared to top; nothing

   // should be marked above top.  The summary data is cleared to the larger of

   // top & new_top.

   MutableSpace* const space = _space_info[id].space();

   HeapWord* const bot = space->bottom();

   HeapWord* const top = space->top();

   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());

   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);

   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));

   _mark_bitmap.clear_range(beg_bit, end_bit);

   const size_t beg_chunk = _summary_data.addr_to_chunk_idx(bot);

   const size_t end_chunk =

     _summary_data.addr_to_chunk_idx(_summary_data.chunk_align_up(max_top));

   _summary_data.clear_range(beg_chunk, end_chunk);

 }

 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)

 {

   // Update the from & to space pointers in space_info, since they are swapped

   // at each young gen gc.  Do the update unconditionally (even though a

   // promotion failure does not swap spaces) because an unknown number of minor

   // collections will have swapped the spaces an unknown number of times.

   TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);

   ParallelScavengeHeap* heap = gc_heap();

   _space_info[from_space_id].set_space(heap->young_gen()->from_space());

   _space_info[to_space_id].set_space(heap->young_gen()->to_space());

   pre_gc_values->fill(heap);

   ParCompactionManager::reset();

   NOT_PRODUCT(_mark_bitmap.reset_counters());

   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)

   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)

   // Increment the invocation count

   heap->increment_total_collections(true);

   // We need to track unique mark sweep invocations as well.

   _total_invocations++;

   if (PrintHeapAtGC) {

     Universe::print_heap_before_gc();

   }

   // Fill in TLABs

   heap->accumulate_statistics_all_tlabs();

   heap->ensure_parsability(true);  // retire TLABs

   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {

     HandleMark hm;  // Discard invalid handles created during verification

     gclog_or_tty->print(" VerifyBeforeGC:");

     Universe::verify(true);

   }

   // Verify object start arrays

   if (VerifyObjectStartArray &&

       VerifyBeforeGC) {

     heap->old_gen()->verify_object_start_array();

     heap->perm_gen()->verify_object_start_array();

   }

   DEBUG_ONLY(mark_bitmap()->verify_clear();)

   DEBUG_ONLY(summary_data().verify_clear();)

   // Have worker threads release resources the next time they run a task.

   gc_task_manager()->release_all_resources();

 }

 void PSParallelCompact::post_compact()

 {

   TraceTime tm("post compact", print_phases(), true, gclog_or_tty);

   // Clear the marking bitmap and summary data and update top() in each space.

   for (unsigned int id = perm_space_id; id < last_space_id; ++id) {

     clear_data_covering_space(SpaceId(id));

     _space_info[id].space()->set_top(_space_info[id].new_top());

   }

   MutableSpace* const eden_space = _space_info[eden_space_id].space();

   MutableSpace* const from_space = _space_info[from_space_id].space();

   MutableSpace* const to_space   = _space_info[to_space_id].space();

   ParallelScavengeHeap* heap = gc_heap();

   bool eden_empty = eden_space->is_empty();

   if (!eden_empty) {

     eden_empty = absorb_live_data_from_eden(heap->size_policy(),

                                             heap->young_gen(), heap->old_gen());

   }

   // Update heap occupancy information which is used as input to the soft ref

   // clearing policy at the next gc.

   Universe::update_heap_info_at_gc();

   bool young_gen_empty = eden_empty && from_space->is_empty() &&

     to_space->is_empty();

   BarrierSet* bs = heap->barrier_set();

   if (bs->is_a(BarrierSet::ModRef)) {

     ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;

     MemRegion old_mr = heap->old_gen()->reserved();

     MemRegion perm_mr = heap->perm_gen()->reserved();

     assert(perm_mr.end() <= old_mr.start(), "Generations out of order");

     if (young_gen_empty) {

       modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));

     } else {

       modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));

     }

   }

   Threads::gc_epilogue();

   CodeCache::gc_epilogue();

   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());

   ref_processor()->enqueue_discovered_references(NULL);

   if (ZapUnusedHeapArea) {

     heap->gen_mangle_unused_area();

   }

   // Update time of last GC

   reset_millis_since_last_gc();

 }

 HeapWord*

 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,

                                                     bool maximum_compaction)

 {

   const size_t chunk_size = ParallelCompactData::ChunkSize;

   const ParallelCompactData& sd = summary_data();

   const MutableSpace* const space = _space_info[id].space();

   HeapWord* const top_aligned_up = sd.chunk_align_up(space->top());

   const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(space->bottom());

   const ChunkData* const end_cp = sd.addr_to_chunk_ptr(top_aligned_up);

   // Skip full chunks at the beginning of the space--they are necessarily part

   // of the dense prefix.

   size_t full_count = 0;

   const ChunkData* cp;

   for (cp = beg_cp; cp < end_cp && cp->data_size() == chunk_size; ++cp) {

     ++full_count;

   }

   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");

   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;

   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;

   if (maximum_compaction || cp == end_cp || interval_ended) {

     _maximum_compaction_gc_num = total_invocations();

     return sd.chunk_to_addr(cp);

   }

   HeapWord* const new_top = _space_info[id].new_top();

   const size_t space_live = pointer_delta(new_top, space->bottom());

   const size_t space_used = space->used_in_words();

   const size_t space_capacity = space->capacity_in_words();

   const double cur_density = double(space_live) / space_capacity;

   const double deadwood_density =

     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;

   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);

   if (TraceParallelOldGCDensePrefix) {

     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,

                   cur_density, deadwood_density, deadwood_goal);

     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "

                   "space_cap=" SIZE_FORMAT,

                   space_live, space_used,

                   space_capacity);

   }

   // XXX - Use binary search?

   HeapWord* dense_prefix = sd.chunk_to_addr(cp);

   const ChunkData* full_cp = cp;

   const ChunkData* const top_cp = sd.addr_to_chunk_ptr(space->top() - 1);

   while (cp < end_cp) {

     HeapWord* chunk_destination = cp->destination();

     const size_t cur_deadwood = pointer_delta(dense_prefix, chunk_destination);

     if (TraceParallelOldGCDensePrefix && Verbose) {

       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "

                     "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),

                     sd.chunk(cp), chunk_destination,

                     dense_prefix, cur_deadwood);

     }

     if (cur_deadwood >= deadwood_goal) {

       // Found the chunk that has the correct amount of deadwood to the left.

       // This typically occurs after crossing a fairly sparse set of chunks, so

       // iterate backwards over those sparse chunks, looking for the chunk that

       // has the lowest density of live objects 'to the right.'

       size_t space_to_left = sd.chunk(cp) * chunk_size;

       size_t live_to_left = space_to_left - cur_deadwood;

       size_t space_to_right = space_capacity - space_to_left;

       size_t live_to_right = space_live - live_to_left;

       double density_to_right = double(live_to_right) / space_to_right;

       while (cp > full_cp) {

         --cp;

         const size_t prev_chunk_live_to_right = live_to_right - cp->data_size();

         const size_t prev_chunk_space_to_right = space_to_right + chunk_size;

         double prev_chunk_density_to_right =

           double(prev_chunk_live_to_right) / prev_chunk_space_to_right;

         if (density_to_right <= prev_chunk_density_to_right) {

           return dense_prefix;

         }

         if (TraceParallelOldGCDensePrefix && Verbose) {

           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "

                         "pc_d2r=%10.8f", sd.chunk(cp), density_to_right,

                         prev_chunk_density_to_right);

         }

         dense_prefix -= chunk_size;

         live_to_right = prev_chunk_live_to_right;

         space_to_right = prev_chunk_space_to_right;

         density_to_right = prev_chunk_density_to_right;

       }

       return dense_prefix;

     }

     dense_prefix += chunk_size;

     ++cp;

   }

   return dense_prefix;

 }

 #ifndef PRODUCT

 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,

                                                  const SpaceId id,

                                                  const bool maximum_compaction,

                                                  HeapWord* const addr)

 {

   const size_t chunk_idx = summary_data().addr_to_chunk_idx(addr);

   ChunkData* const cp = summary_data().chunk(chunk_idx);

   const MutableSpace* const space = _space_info[id].space();

   HeapWord* const new_top = _space_info[id].new_top();

   const size_t space_live = pointer_delta(new_top, space->bottom());

   const size_t dead_to_left = pointer_delta(addr, cp->destination());

   const size_t space_cap = space->capacity_in_words();

   const double dead_to_left_pct = double(dead_to_left) / space_cap;

   const size_t live_to_right = new_top - cp->destination();

   const size_t dead_to_right = space->top() - addr - live_to_right;

   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "

                 "spl=" SIZE_FORMAT " "

                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "

                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT

                 " ratio=%10.8f",

                 algorithm, addr, chunk_idx,

                 space_live,

                 dead_to_left, dead_to_left_pct,

                 dead_to_right, live_to_right,

                 double(dead_to_right) / live_to_right);

 }

 #endif  // #ifndef PRODUCT

 // Return a fraction indicating how much of the generation can be treated as

 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution

 // based on the density of live objects in the generation to determine a limit,

 // which is then adjusted so the return value is min_percent when the density is

 // 1.

 //

 // The following table shows some return values for a different values of the

 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and

 // min_percent is 1.

 //

 //                          fraction allowed as dead wood

 //         -----------------------------------------------------------------

 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95

 // ------- ---------- ---------- ---------- ---------- ---------- ----------

 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000

 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941

 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272

 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066

 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975

 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313

 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132

 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289

 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500

 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386

 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510

 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386

 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500

 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289

 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132

 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313

 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975

 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066

 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272

 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941

 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000

 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)

 {

   assert(_dwl_initialized, "uninitialized");

   // The raw limit is the value of the normal distribution at x = density.

   const double raw_limit = normal_distribution(density);

   // Adjust the raw limit so it becomes the minimum when the density is 1.

   //

   // First subtract the adjustment value (which is simply the precomputed value

   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.

   // Then add the minimum value, so the minimum is returned when the density is

   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.

   const double min = double(min_percent) / 100.0;

   const double limit = raw_limit - _dwl_adjustment + min;

   return MAX2(limit, 0.0);

 }

 ParallelCompactData::ChunkData*

 PSParallelCompact::first_dead_space_chunk(const ChunkData* beg,

                                           const ChunkData* end)

 {

   const size_t chunk_size = ParallelCompactData::ChunkSize;

   ParallelCompactData& sd = summary_data();

   size_t left = sd.chunk(beg);

   size_t right = end > beg ? sd.chunk(end) - 1 : left;

   // Binary search.

   while (left < right) {

     // Equivalent to (left + right) / 2, but does not overflow.

     const size_t middle = left + (right - left) / 2;

     ChunkData* const middle_ptr = sd.chunk(middle);

     HeapWord* const dest = middle_ptr->destination();

     HeapWord* const addr = sd.chunk_to_addr(middle);

     assert(dest != NULL, "sanity");

     assert(dest <= addr, "must move left");

     if (middle > left && dest < addr) {

       right = middle - 1;

     } else if (middle < right && middle_ptr->data_size() == chunk_size) {

       left = middle + 1;

     } else {

       return middle_ptr;

     }

   }

   return sd.chunk(left);

 }

 ParallelCompactData::ChunkData*

 PSParallelCompact::dead_wood_limit_chunk(const ChunkData* beg,

                                          const ChunkData* end,

                                          size_t dead_words)

 {

   ParallelCompactData& sd = summary_data();

   size_t left = sd.chunk(beg);

   size_t right = end > beg ? sd.chunk(end) - 1 : left;

   // Binary search.

   while (left < right) {

     // Equivalent to (left + right) / 2, but does not overflow.

     const size_t middle = left + (right - left) / 2;

     ChunkData* const middle_ptr = sd.chunk(middle);

     HeapWord* const dest = middle_ptr->destination();

     HeapWord* const addr = sd.chunk_to_addr(middle);

     assert(dest != NULL, "sanity");

     assert(dest <= addr, "must move left");

     const size_t dead_to_left = pointer_delta(addr, dest);

     if (middle > left && dead_to_left > dead_words) {

       right = middle - 1;

     } else if (middle < right && dead_to_left < dead_words) {

       left = middle + 1;

     } else {

       return middle_ptr;

     }

   }

   return sd.chunk(left);

 }

 // The result is valid during the summary phase, after the initial summarization

 // of each space into itself, and before final summarization.

 inline double

 PSParallelCompact::reclaimed_ratio(const ChunkData* const cp,

                                    HeapWord* const bottom,

                                    HeapWord* const top,

                                    HeapWord* const new_top)

 {

   ParallelCompactData& sd = summary_data();

   assert(cp != NULL, "sanity");

   assert(bottom != NULL, "sanity");

   assert(top != NULL, "sanity");

   assert(new_top != NULL, "sanity");

   assert(top >= new_top, "summary data problem?");

   assert(new_top > bottom, "space is empty; should not be here");

   assert(new_top >= cp->destination(), "sanity");

   assert(top >= sd.chunk_to_addr(cp), "sanity");

   HeapWord* const destination = cp->destination();

   const size_t dense_prefix_live  = pointer_delta(destination, bottom);

   const size_t compacted_region_live = pointer_delta(new_top, destination);

   const size_t compacted_region_used = pointer_delta(top, sd.chunk_to_addr(cp));

   const size_t reclaimable = compacted_region_used - compacted_region_live;

   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;

   return double(reclaimable) / divisor;

 }

 // Return the address of the end of the dense prefix, a.k.a. the start of the

 // compacted region.  The address is always on a chunk boundary.

 //

 // Completely full chunks at the left are skipped, since no compaction can occur

 // in those chunks.  Then the maximum amount of dead wood to allow is computed,

 // based on the density (amount live / capacity) of the generation; the chunk

 // with approximately that amount of dead space to the left is identified as the

 // limit chunk.  Chunks between the last completely full chunk and the limit

 // chunk are scanned and the one that has the best (maximum) reclaimed_ratio()

 // is selected.

 HeapWord*

 PSParallelCompact::compute_dense_prefix(const SpaceId id,

                                         bool maximum_compaction)

 {

   const size_t chunk_size = ParallelCompactData::ChunkSize;

   const ParallelCompactData& sd = summary_data();

   const MutableSpace* const space = _space_info[id].space();

   HeapWord* const top = space->top();

   HeapWord* const top_aligned_up = sd.chunk_align_up(top);

   HeapWord* const new_top = _space_info[id].new_top();

   HeapWord* const new_top_aligned_up = sd.chunk_align_up(new_top);

   HeapWord* const bottom = space->bottom();

   const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(bottom);

   const ChunkData* const top_cp = sd.addr_to_chunk_ptr(top_aligned_up);

   const ChunkData* const new_top_cp = sd.addr_to_chunk_ptr(new_top_aligned_up);

   // Skip full chunks at the beginning of the space--they are necessarily part

   // of the dense prefix.

   const ChunkData* const full_cp = first_dead_space_chunk(beg_cp, new_top_cp);

   assert(full_cp->destination() == sd.chunk_to_addr(full_cp) ||

          space->is_empty(), "no dead space allowed to the left");

   assert(full_cp->data_size() < chunk_size || full_cp == new_top_cp - 1,

          "chunk must have dead space");

   // The gc number is saved whenever a maximum compaction is done, and used to

   // determine when the maximum compaction interval has expired.  This avoids

   // successive max compactions for different reasons.

   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");

   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;

   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||

     total_invocations() == HeapFirstMaximumCompactionCount;

   if (maximum_compaction || full_cp == top_cp || interval_ended) {

     _maximum_compaction_gc_num = total_invocations();

     return sd.chunk_to_addr(full_cp);

   }

   const size_t space_live = pointer_delta(new_top, bottom);

   const size_t space_used = space->used_in_words();

   const size_t space_capacity = space->capacity_in_words();

   const double density = double(space_live) / double(space_capacity);

   const size_t min_percent_free =

           id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;

   const double limiter = dead_wood_limiter(density, min_percent_free);

   const size_t dead_wood_max = space_used - space_live;

   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),

                                       dead_wood_max);

   if (TraceParallelOldGCDensePrefix) {

     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "

                   "space_cap=" SIZE_FORMAT,

                   space_live, space_used,

                   space_capacity);

     tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "

                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,

                   density, min_percent_free, limiter,

                   dead_wood_max, dead_wood_limit);

   }

   // Locate the chunk with the desired amount of dead space to the left.

   const ChunkData* const limit_cp =

     dead_wood_limit_chunk(full_cp, top_cp, dead_wood_limit);

   // Scan from the first chunk with dead space to the limit chunk and find the

   // one with the best (largest) reclaimed ratio.

   double best_ratio = 0.0;

   const ChunkData* best_cp = full_cp;

   for (const ChunkData* cp = full_cp; cp < limit_cp; ++cp) {

     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);

     if (tmp_ratio > best_ratio) {

       best_cp = cp;

       best_ratio = tmp_ratio;

     }

   }

 #if     0

   // Something to consider:  if the chunk with the best ratio is 'close to' the

   // first chunk w/free space, choose the first chunk with free space

   // ("first-free").  The first-free chunk is usually near the start of the

   // heap, which means we are copying most of the heap already, so copy a bit

   // more to get complete compaction.

   if (pointer_delta(best_cp, full_cp, sizeof(ChunkData)) < 4) {

     _maximum_compaction_gc_num = total_invocations();

     best_cp = full_cp;

   }

 #endif  // #if 0

   return sd.chunk_to_addr(best_cp);

 }

 void PSParallelCompact::summarize_spaces_quick()

 {

   for (unsigned int i = 0; i < last_space_id; ++i) {

     const MutableSpace* space = _space_info[i].space();

     bool result = _summary_data.summarize(space->bottom(), space->end(),

                                           space->bottom(), space->top(),

                                           _space_info[i].new_top_addr());

     assert(result, "should never fail");

     _space_info[i].set_dense_prefix(space->bottom());

   }

 }

 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)

 {

   HeapWord* const dense_prefix_end = dense_prefix(id);

   const ChunkData* chunk = _summary_data.addr_to_chunk_ptr(dense_prefix_end);

   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);

   if (dead_space_crosses_boundary(chunk, dense_prefix_bit)) {

     // Only enough dead space is filled so that any remaining dead space to the

     // left is larger than the minimum filler object.  (The remainder is filled

     // during the copy/update phase.)

     //

     // The size of the dead space to the right of the boundary is not a

     // concern, since compaction will be able to use whatever space is

     // available.

     //

     // Here '||' is the boundary, 'x' represents a don't care bit and a box

     // surrounds the space to be filled with an object.

     //

     // In the 32-bit VM, each bit represents two 32-bit words:

     //                              +---+

     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...

     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...

     //                              +---+

     //

     // In the 64-bit VM, each bit represents one 64-bit word:

     //                              +------------+

     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...

     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...

     //                              +------------+

     //                          +-------+

     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...

     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...

     //                          +-------+

     //                      +-----------+

     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...

     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...

     //                      +-----------+

     //                          +-------+

     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...

     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...

     //                          +-------+

     // Initially assume case a, c or e will apply.

     size_t obj_len = (size_t)oopDesc::header_size();

     HeapWord* obj_beg = dense_prefix_end - obj_len;

 #ifdef  _LP64

     if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {

       // Case b above.

       obj_beg = dense_prefix_end - 1;

     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&

                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {

       // Case d above.

       obj_beg = dense_prefix_end - 3;

       obj_len = 3;

     }

 #endif  // #ifdef _LP64

     MemRegion region(obj_beg, obj_len);

     SharedHeap::fill_region_with_object(region);

     _mark_bitmap.mark_obj(obj_beg, obj_len);

     _summary_data.add_obj(obj_beg, obj_len);

     assert(start_array(id) != NULL, "sanity");

     start_array(id)->allocate_block(obj_beg);

   }

 }

 void

 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)

 {

   assert(id < last_space_id, "id out of range");

   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),

          "should have been set in summarize_spaces_quick()");

   const MutableSpace* space = _space_info[id].space();

   if (_space_info[id].new_top() != space->bottom()) {

     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);

     _space_info[id].set_dense_prefix(dense_prefix_end);

 #ifndef PRODUCT

     if (TraceParallelOldGCDensePrefix) {

       print_dense_prefix_stats("ratio", id, maximum_compaction,

                                dense_prefix_end);

       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);

       print_dense_prefix_stats("density", id, maximum_compaction, addr);

     }

 #endif  // #ifndef PRODUCT

     // If dead space crosses the dense prefix boundary, it is (at least

     // partially) filled with a dummy object, marked live and added to the

     // summary data.  This simplifies the copy/update phase and must be done

     // before the final locations of objects are determined, to prevent leaving

     // a fragment of dead space that is too small to fill with an object.

     if (!maximum_compaction && dense_prefix_end != space->bottom()) {

       fill_dense_prefix_end(id);

     }

     // Compute the destination of each Chunk, and thus each object.

     _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);

     _summary_data.summarize(dense_prefix_end, space->end(),

                             dense_prefix_end, space->top(),

                             _space_info[id].new_top_addr());

   }

   if (TraceParallelOldGCSummaryPhase) {

     const size_t chunk_size = ParallelCompactData::ChunkSize;

     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();

     const size_t dp_chunk = _summary_data.addr_to_chunk_idx(dense_prefix_end);

     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());

     HeapWord* const new_top = _space_info[id].new_top();

     const HeapWord* nt_aligned_up = _summary_data.chunk_align_up(new_top);

     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);

     tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "

                   "dp_chunk=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "

                   "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,

                   id, space->capacity_in_words(), dense_prefix_end,

                   dp_chunk, dp_words / chunk_size,

                   cr_words / chunk_size, new_top);

   }

 }

 void PSParallelCompact::summary_phase(ParCompactionManager* cm,

                                       bool maximum_compaction)

 {

   EventMark m("2 summarize");

   TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);

   // trace("2");

 #ifdef  ASSERT

   if (TraceParallelOldGCMarkingPhase) {

     tty->print_cr("add_obj_count=" SIZE_FORMAT " "

                   "add_obj_bytes=" SIZE_FORMAT,

                   add_obj_count, add_obj_size * HeapWordSize);

     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "

                   "mark_bitmap_bytes=" SIZE_FORMAT,

                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);

   }

 #endif  // #ifdef ASSERT

   // Quick summarization of each space into itself, to see how much is live.

   summarize_spaces_quick();

   if (TraceParallelOldGCSummaryPhase) {

     tty->print_cr("summary_phase:  after summarizing each space to self");

     Universe::print();

     NOT_PRODUCT(print_chunk_ranges());

     if (Verbose) {

       NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));

     }

   }

   // The amount of live data that will end up in old space (assuming it fits).

   size_t old_space_total_live = 0;

   unsigned int id;

   for (id = old_space_id; id < last_space_id; ++id) {

     old_space_total_live += pointer_delta(_space_info[id].new_top(),

                                           _space_info[id].space()->bottom());

   }

   const MutableSpace* old_space = _space_info[old_space_id].space();

   if (old_space_total_live > old_space->capacity_in_words()) {

     // XXX - should also try to expand

     maximum_compaction = true;

   } else if (!UseParallelOldGCDensePrefix) {

     maximum_compaction = true;

   }

   // Permanent and Old generations.

   summarize_space(perm_space_id, maximum_compaction);

   summarize_space(old_space_id, maximum_compaction);

   // Summarize the remaining spaces (those in the young gen) into old space.  If

   // the live data from a space doesn't fit, the existing summarization is left

   // intact, so the data is compacted down within the space itself.

   HeapWord** new_top_addr = _space_info[old_space_id].new_top_addr();

   HeapWord* const target_space_end = old_space->end();

   for (id = eden_space_id; id < last_space_id; ++id) {

     const MutableSpace* space = _space_info[id].space();

     const size_t live = pointer_delta(_space_info[id].new_top(),

                                       space->bottom());

     const size_t available = pointer_delta(target_space_end, *new_top_addr);

     if (live > 0 && live <= available) {

       // All the live data will fit.

       if (TraceParallelOldGCSummaryPhase) {

         tty->print_cr("summarizing %d into old_space @ " PTR_FORMAT,

                       id, *new_top_addr);

       }

       _summary_data.summarize(*new_top_addr, target_space_end,

                               space->bottom(), space->top(),

                               new_top_addr);

       // Clear the source_chunk field for each chunk in the space.

       HeapWord* const new_top = _space_info[id].new_top();

       HeapWord* const clear_end = _summary_data.chunk_align_up(new_top);

       ChunkData* beg_chunk = _summary_data.addr_to_chunk_ptr(space->bottom());

       ChunkData* end_chunk = _summary_data.addr_to_chunk_ptr(clear_end);

       while (beg_chunk < end_chunk) {

         beg_chunk->set_source_chunk(0);

         ++beg_chunk;

       }

       // Reset the new_top value for the space.

       _space_info[id].set_new_top(space->bottom());

     }

   }

   // Fill in the block data after any changes to the chunks have

   // been made.

 #ifdef  ASSERT

   summarize_blocks(cm, perm_space_id);

   summarize_blocks(cm, old_space_id);

 #else

   if (!UseParallelOldGCChunkPointerCalc) {

     summarize_blocks(cm, perm_space_id);

     summarize_blocks(cm, old_space_id);

   }

 #endif

   if (TraceParallelOldGCSummaryPhase) {

     tty->print_cr("summary_phase:  after final summarization");

     Universe::print();

     NOT_PRODUCT(print_chunk_ranges());

     if (Verbose) {

       NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));

     }

   }

 }

 // Fill in the BlockData.

 // Iterate over the spaces and within each space iterate over

 // the chunks and fill in the BlockData for each chunk.

 void PSParallelCompact::summarize_blocks(ParCompactionManager* cm,

                                          SpaceId first_compaction_space_id) {

 #if     0

   DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(1);)

   for (SpaceId cur_space_id = first_compaction_space_id;

        cur_space_id != last_space_id;

        cur_space_id = next_compaction_space_id(cur_space_id)) {

     // Iterate over the chunks in the space

     size_t start_chunk_index =

       _summary_data.addr_to_chunk_idx(space(cur_space_id)->bottom());

     BitBlockUpdateClosure bbu(mark_bitmap(),

                               cm,

                               start_chunk_index);

     // Iterate over blocks.

     for (size_t chunk_index =  start_chunk_index;

          chunk_index < _summary_data.chunk_count() &&

          _summary_data.chunk_to_addr(chunk_index) < space(cur_space_id)->top();

          chunk_index++) {

       // Reset the closure for the new chunk.  Note that the closure

       // maintains some data that does not get reset for each chunk

       // so a new instance of the closure is no appropriate.

       bbu.reset_chunk(chunk_index);

       // Start the iteration with the first live object.  This

       // may return the end of the chunk.  That is acceptable since

       // it will properly limit the iterations.

       ParMarkBitMap::idx_t left_offset = mark_bitmap()->addr_to_bit(

         _summary_data.first_live_or_end_in_chunk(chunk_index));

       // End the iteration at the end of the chunk.

       HeapWord* chunk_addr = _summary_data.chunk_to_addr(chunk_index);

       HeapWord* chunk_end = chunk_addr + ParallelCompactData::ChunkSize;

       ParMarkBitMap::idx_t right_offset =

         mark_bitmap()->addr_to_bit(chunk_end);

       // Blocks that have not objects starting in them can be

       // skipped because their data will never be used.

       if (left_offset < right_offset) {

         // Iterate through the objects in the chunk.

         ParMarkBitMap::idx_t last_offset =

           mark_bitmap()->pair_iterate(&bbu, left_offset, right_offset);

         // If last_offset is less than right_offset, then the iterations

         // terminated while it was looking for an end bit.  "last_offset"

         // is then the offset for the last start bit.  In this situation

         // the "offset" field for the next block to the right (_cur_block + 1)

         // will not have been update although there may be live data

         // to the left of the chunk.

         size_t cur_block_plus_1 = bbu.cur_block() + 1;

         HeapWord* cur_block_plus_1_addr =

         _summary_data.block_to_addr(bbu.cur_block()) +

         ParallelCompactData::BlockSize;

         HeapWord* last_offset_addr = mark_bitmap()->bit_to_addr(last_offset);

  #if 1  // This code works.  The else doesn't but should.  Why does it?

         // The current block (cur_block()) has already been updated.

         // The last block that may need to be updated is either the

         // next block (current block + 1) or the block where the

         // last object starts (which can be greater than the

         // next block if there were no objects found in intervening

         // blocks).

         size_t last_block =

           MAX2(bbu.cur_block() + 1,

                _summary_data.addr_to_block_idx(last_offset_addr));

  #else

         // The current block has already been updated.  The only block

         // that remains to be updated is the block where the last

         // object in the chunk starts.

         size_t last_block = _summary_data.addr_to_block_idx(last_offset_addr);

  #endif

         assert_bit_is_start(last_offset);

         assert((last_block == _summary_data.block_count()) ||

              (_summary_data.block(last_block)->raw_offset() == 0),

           "Should not have been set");

         // Is the last block still in the current chunk?  If still

         // in this chunk, update the last block (the counting that

         // included the current block is meant for the offset of the last

         // block).  If not in this chunk, do nothing.  Should not

         // update a block in the next chunk.

         if (ParallelCompactData::chunk_contains_block(bbu.chunk_index(),

                                                       last_block)) {

           if (last_offset < right_offset) {

             // The last object started in this chunk but ends beyond

             // this chunk.  Update the block for this last object.

             assert(mark_bitmap()->is_marked(last_offset), "Should be marked");

             // No end bit was found.  The closure takes care of

             // the cases where

             //   an objects crosses over into the next block

             //   an objects starts and ends in the next block

             // It does not handle the case where an object is

             // the first object in a later block and extends

             // past the end of the chunk (i.e., the closure

             // only handles complete objects that are in the range

             // it is given).  That object is handed back here

             // for any special consideration necessary.

             //

             // Is the first bit in the last block a start or end bit?

             //

             // If the partial object ends in the last block L,

             // then the 1st bit in L may be an end bit.

             //

             // Else does the last object start in a block after the current

             // block? A block AA will already have been updated if an

             // object ends in the next block AA+1.  An object found to end in

             // the AA+1 is the trigger that updates AA.  Objects are being

             // counted in the current block for updaing a following

             // block.  An object may start in later block

             // block but may extend beyond the last block in the chunk.

             // Updates are only done when the end of an object has been

             // found. If the last object (covered by block L) starts

             // beyond the current block, then no object ends in L (otherwise

             // L would be the current block).  So the first bit in L is

             // a start bit.

             //

             // Else the last objects start in the current block and ends

             // beyond the chunk.  The current block has already been

             // updated and there is no later block (with an object

             // starting in it) that needs to be updated.

             //

             if (_summary_data.partial_obj_ends_in_block(last_block)) {

               _summary_data.block(last_block)->set_end_bit_offset(

                 bbu.live_data_left());

             } else if (last_offset_addr >= cur_block_plus_1_addr) {

               //   The start of the object is on a later block

               // (to the right of the current block and there are no

               // complete live objects to the left of this last object

               // within the chunk.

               //   The first bit in the block is for the start of the

               // last object.

               _summary_data.block(last_block)->set_start_bit_offset(

                 bbu.live_data_left());

             } else {

               //   The start of the last object was found in

               // the current chunk (which has already

               // been updated).

               assert(bbu.cur_block() ==

                       _summary_data.addr_to_block_idx(last_offset_addr),

                 "Should be a block already processed");

             }

 #ifdef ASSERT

             // Is there enough block information to find this object?

             // The destination of the chunk has not been set so the

             // values returned by calc_new_pointer() and

             // block_calc_new_pointer() will only be

             // offsets.  But they should agree.

             HeapWord* moved_obj_with_chunks =

               _summary_data.chunk_calc_new_pointer(last_offset_addr);

             HeapWord* moved_obj_with_blocks =

               _summary_data.calc_new_pointer(last_offset_addr);

             assert(moved_obj_with_chunks == moved_obj_with_blocks,

               "Block calculation is wrong");

 #endif

           } else if (last_block < _summary_data.block_count()) {

             // Iterations ended looking for a start bit (but

             // did not run off the end of the block table).

             _summary_data.block(last_block)->set_start_bit_offset(

               bbu.live_data_left());

           }

         }

 #ifdef ASSERT

         // Is there enough block information to find this object?

           HeapWord* left_offset_addr = mark_bitmap()->bit_to_addr(left_offset);

         HeapWord* moved_obj_with_chunks =

           _summary_data.calc_new_pointer(left_offset_addr);

         HeapWord* moved_obj_with_blocks =

           _summary_data.calc_new_pointer(left_offset_addr);

           assert(moved_obj_with_chunks == moved_obj_with_blocks,

           "Block calculation is wrong");

 #endif

         // Is there another block after the end of this chunk?

 #ifdef ASSERT

         if (last_block < _summary_data.block_count()) {

         // No object may have been found in a block.  If that

         // block is at the end of the chunk, the iteration will

         // terminate without incrementing the current block so

         // that the current block is not the last block in the

         // chunk.  That situation precludes asserting that the

         // current block is the last block in the chunk.  Assert

         // the lesser condition that the current block does not

         // exceed the chunk.

           assert(_summary_data.block_to_addr(last_block) <=

                (_summary_data.chunk_to_addr(chunk_index) +

                  ParallelCompactData::ChunkSize),

               "Chunk and block inconsistency");

           assert(last_offset <= right_offset, "Iteration over ran end");

         }

 #endif

       }

 #ifdef ASSERT

       if (PrintGCDetails && Verbose) {

         if (_summary_data.chunk(chunk_index)->partial_obj_size() == 1) {

           size_t first_block =

             chunk_index / ParallelCompactData::BlocksPerChunk;

           gclog_or_tty->print_cr("first_block " PTR_FORMAT

             " _offset " PTR_FORMAT

             "_first_is_start_bit %d",

             first_block,

             _summary_data.block(first_block)->raw_offset(),

             _summary_data.block(first_block)->first_is_start_bit());

         }

       }

 #endif

     }

   }

   DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(16);)

 #endif  // #if 0

 }

 // This method should contain all heap-specific policy for invoking a full

 // collection.  invoke_no_policy() will only attempt to compact the heap; it

 // will do nothing further.  If we need to bail out for policy reasons, scavenge

 // before full gc, or any other specialized behavior, it needs to be added here.

 //

 // Note that this method should only be called from the vm_thread while at a

 // safepoint.

 void PSParallelCompact::invoke(bool maximum_heap_compaction) {

   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");

   assert(Thread::current() == (Thread*)VMThread::vm_thread(),

          "should be in vm thread");

   ParallelScavengeHeap* heap = gc_heap();

   GCCause::Cause gc_cause = heap->gc_cause();

   assert(!heap->is_gc_active(), "not reentrant");

   PSAdaptiveSizePolicy* policy = heap->size_policy();

   // Before each allocation/collection attempt, find out from the

   // policy object if GCs are, on the whole, taking too long. If so,

   // bail out without attempting a collection.  The exceptions are

   // for explicitly requested GC's.

   if (!policy->gc_time_limit_exceeded() ||

       GCCause::is_user_requested_gc(gc_cause) ||

       GCCause::is_serviceability_requested_gc(gc_cause)) {

     IsGCActiveMark mark;

     if (ScavengeBeforeFullGC) {

       PSScavenge::invoke_no_policy();

     }

     PSParallelCompact::invoke_no_policy(maximum_heap_compaction);

   }

 }

 bool ParallelCompactData::chunk_contains(size_t chunk_index, HeapWord* addr) {

   size_t addr_chunk_index = addr_to_chunk_idx(addr);

   return chunk_index == addr_chunk_index;

 }

 bool ParallelCompactData::chunk_contains_block(size_t chunk_index,

                                                size_t block_index) {

   size_t first_block_in_chunk = chunk_index * BlocksPerChunk;

   size_t last_block_in_chunk = (chunk_index + 1) * BlocksPerChunk - 1;

   return (first_block_in_chunk <= block_index) &&

          (block_index <= last_block_in_chunk);

 }

 // This method contains no policy. You should probably

 // be calling invoke() instead.

 void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {

   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");

   assert(ref_processor() != NULL, "Sanity");

   if (GC_locker::check_active_before_gc()) {

     return;

   }

   TimeStamp marking_start;

   TimeStamp compaction_start;

   TimeStamp collection_exit;

   ParallelScavengeHeap* heap = gc_heap();

   GCCause::Cause gc_cause = heap->gc_cause();

   PSYoungGen* young_gen = heap->young_gen();

   PSOldGen* old_gen = heap->old_gen();

   PSPermGen* perm_gen = heap->perm_gen();

   PSAdaptiveSizePolicy* size_policy = heap->size_policy();

   if (ZapUnusedHeapArea) {

     // Save information needed to minimize mangling

     heap->record_gen_tops_before_GC();

   }

   _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;

   // Make sure data structures are sane, make the heap parsable, and do other

   // miscellaneous bookkeeping.

   PreGCValues pre_gc_values;

   pre_compact(&pre_gc_values);

   // Get the compaction manager reserved for the VM thread.

   ParCompactionManager* const vmthread_cm =

     ParCompactionManager::manager_array(gc_task_manager()->workers());

   // Place after pre_compact() where the number of invocations is incremented.

   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());

   {

     ResourceMark rm;

     HandleMark hm;

     const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;

     // This is useful for debugging but don't change the output the

     // the customer sees.

     const char* gc_cause_str = "Full GC";

     if (is_system_gc && PrintGCDetails) {

       gc_cause_str = "Full GC (System)";

     }

     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);

     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);

     TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);

     TraceCollectorStats tcs(counters());

     TraceMemoryManagerStats tms(true /* Full GC */);

     if (TraceGen1Time) accumulated_time()->start();

     // Let the size policy know we're starting

     size_policy->major_collection_begin();

     // When collecting the permanent generation methodOops may be moving,

     // so we either have to flush all bcp data or convert it into bci.

     CodeCache::gc_prologue();

     Threads::gc_prologue();

     NOT_PRODUCT(ref_processor()->verify_no_references_recorded());

     COMPILER2_PRESENT(DerivedPointerTable::clear());

     ref_processor()->enable_discovery();

     bool marked_for_unloading = false;

     marking_start.update();

     marking_phase(vmthread_cm, maximum_heap_compaction);

 #ifndef PRODUCT

     if (TraceParallelOldGCMarkingPhase) {

       gclog_or_tty->print_cr("marking_phase: cas_tries %d  cas_retries %d "

         "cas_by_another %d",

         mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),

         mark_bitmap()->cas_by_another());

     }

 #endif  // #ifndef PRODUCT

     bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc;

     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);

     COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));

     COMPILER2_PRESENT(DerivedPointerTable::set_active(false));

     // adjust_roots() updates Universe::_intArrayKlassObj which is

     // needed by the compaction for filling holes in the dense prefix.

     adjust_roots();

     compaction_start.update();

     // Does the perm gen always have to be done serially because

     // klasses are used in the update of an object?

     compact_perm(vmthread_cm);

     if (UseParallelOldGCCompacting) {

       compact();

     } else {

       compact_serial(vmthread_cm);

     }

     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be

     // done before resizing.

     post_compact();

     // Let the size policy know we're done

     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);

     if (UseAdaptiveSizePolicy) {

       if (PrintAdaptiveSizePolicy) {

         gclog_or_tty->print("AdaptiveSizeStart: ");

         gclog_or_tty->stamp();

         gclog_or_tty->print_cr(" collection: %d ",

                        heap->total_collections());

         if (Verbose) {

           gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"

             " perm_gen_capacity: %d ",

             old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),

             perm_gen->capacity_in_bytes());

         }

       }

       // Don't check if the size_policy is ready here.  Let

       // the size_policy check that internally.

       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&

           ((gc_cause != GCCause::_java_lang_system_gc) ||

             UseAdaptiveSizePolicyWithSystemGC)) {

         // Calculate optimal free space amounts

         assert(young_gen->max_size() >

           young_gen->from_space()->capacity_in_bytes() +

           young_gen->to_space()->capacity_in_bytes(),

           "Sizes of space in young gen are out-of-bounds");

         size_t max_eden_size = young_gen->max_size() -

           young_gen->from_space()->capacity_in_bytes() -

           young_gen->to_space()->capacity_in_bytes();

         size_policy->compute_generation_free_space(

                               young_gen->used_in_bytes(),

                               young_gen->eden_space()->used_in_bytes(),

                               old_gen->used_in_bytes(),

                               perm_gen->used_in_bytes(),

                               young_gen->eden_space()->capacity_in_bytes(),

                               old_gen->max_gen_size(),

                               max_eden_size,

                               true /* full gc*/,

                               gc_cause);

         heap->resize_old_gen(

           size_policy->calculated_old_free_size_in_bytes());

         // Don't resize the young generation at an major collection.  A

         // desired young generation size may have been calculated but

         // resizing the young generation complicates the code because the

         // resizing of the old generation may have moved the boundary

         // between the young generation and the old generation.  Let the

         // young generation resizing happen at the minor collections.

       }

       if (PrintAdaptiveSizePolicy) {

         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",

                        heap->total_collections());

       }

     }

     if (UsePerfData) {

       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();

       counters->update_counters();

       counters->update_old_capacity(old_gen->capacity_in_bytes());

       counters->update_young_capacity(young_gen->capacity_in_bytes());

     }

     heap->resize_all_tlabs();

     // We collected the perm gen, so we'll resize it here.

     perm_gen->compute_new_size(pre_gc_values.perm_gen_used());

     if (TraceGen1Time) accumulated_time()->stop();

     if (PrintGC) {

       if (PrintGCDetails) {

         // No GC timestamp here.  This is after GC so it would be confusing.

         young_gen->print_used_change(pre_gc_values.young_gen_used());

         old_gen->print_used_change(pre_gc_values.old_gen_used());

         heap->print_heap_change(pre_gc_values.heap_used());

         // Print perm gen last (print_heap_change() excludes the perm gen).

         perm_gen->print_used_change(pre_gc_values.perm_gen_used());

       } else {

         heap->print_heap_change(pre_gc_values.heap_used());

       }

     }

     // Track memory usage and detect low memory

     MemoryService::track_memory_usage();

     heap->update_counters();

     if (PrintGCDetails) {

       if (size_policy->print_gc_time_limit_would_be_exceeded()) {

         if (size_policy->gc_time_limit_exceeded()) {

           gclog_or_tty->print_cr("      GC time is exceeding GCTimeLimit "

             "of %d%%", GCTimeLimit);

         } else {

           gclog_or_tty->print_cr("      GC time would exceed GCTimeLimit "

             "of %d%%", GCTimeLimit);

         }

       }

       size_policy->set_print_gc_time_limit_would_be_exceeded(false);

     }

   }

   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {

     HandleMark hm;  // Discard invalid handles created during verification

     gclog_or_tty->print(" VerifyAfterGC:");

     Universe::verify(false);

   }

   // Re-verify object start arrays

   if (VerifyObjectStartArray &&

       VerifyAfterGC) {

     old_gen->verify_object_start_array();

     perm_gen->verify_object_start_array();

   }

   if (ZapUnusedHeapArea) {

     old_gen->object_space()->check_mangled_unused_area_complete();

     perm_gen->object_space()->check_mangled_unused_area_complete();

   }

   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());

   collection_exit.update();

   if (PrintHeapAtGC) {

     Universe::print_heap_after_gc();

   }

   if (PrintGCTaskTimeStamps) {

     gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "

                            INT64_FORMAT,

                            marking_start.ticks(), compaction_start.ticks(),

                            collection_exit.ticks());

     gc_task_manager()->print_task_time_stamps();

   }

 }

 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,

                                              PSYoungGen* young_gen,

                                              PSOldGen* old_gen) {

   MutableSpace* const eden_space = young_gen->eden_space();

   assert(!eden_space->is_empty(), "eden must be non-empty");

   assert(young_gen->virtual_space()->alignment() ==

          old_gen->virtual_space()->alignment(), "alignments do not match");

   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {

     return false;

   }

   // Both generations must be completely committed.

   if (young_gen->virtual_space()->uncommitted_size() != 0) {

     return false;

   }

   if (old_gen->virtual_space()->uncommitted_size() != 0) {

     return false;

   }

   // Figure out how much to take from eden.  Include the average amount promoted

   // in the total; otherwise the next young gen GC will simply bail out to a

   // full GC.

   const size_t alignment = old_gen->virtual_space()->alignment();

   const size_t eden_used = eden_space->used_in_bytes();

   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();

   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);

   const size_t eden_capacity = eden_space->capacity_in_bytes();

   if (absorb_size >= eden_capacity) {

     return false; // Must leave some space in eden.

   }

   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;

   if (new_young_size < young_gen->min_gen_size()) {

     return false; // Respect young gen minimum size.

   }

   if (TraceAdaptiveGCBoundary && Verbose) {

     gclog_or_tty->print(" absorbing " SIZE_FORMAT "K:  "

                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "

                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "

                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",

                         absorb_size / K,

                         eden_capacity / K, (eden_capacity - absorb_size) / K,

                         young_gen->from_space()->used_in_bytes() / K,

                         young_gen->to_space()->used_in_bytes() / K,

                         young_gen->capacity_in_bytes() / K, new_young_size / K);

   }

   // Fill the unused part of the old gen.

   MutableSpace* const old_space = old_gen->object_space();

   MemRegion old_gen_unused(old_space->top(), old_space->end());

   if (!old_gen_unused.is_empty()) {

     SharedHeap::fill_region_with_object(old_gen_unused);

   }

   // Take the live data from eden and set both top and end in the old gen to

   // eden top.  (Need to set end because reset_after_change() mangles the region

   // from end to virtual_space->high() in debug builds).

   HeapWord* const new_top = eden_space->top();

   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),

                                         absorb_size);

   young_gen->reset_after_change();

   old_space->set_top(new_top);

   old_space->set_end(new_top);

   old_gen->reset_after_change();

   // Update the object start array for the filler object and the data from eden.

   ObjectStartArray* const start_array = old_gen->start_array();

   HeapWord* const start = old_gen_unused.start();

   for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) {

     start_array->allocate_block(addr);

   }

   // Could update the promoted average here, but it is not typically updated at

   // full GCs and the value to use is unclear.  Something like

   //

   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.

   size_policy->set_bytes_absorbed_from_eden(absorb_size);

   return true;

 }

 GCTaskManager* const PSParallelCompact::gc_task_manager() {

   assert(ParallelScavengeHeap::gc_task_manager() != NULL,

     "shouldn't return NULL");

   return ParallelScavengeHeap::gc_task_manager();

 }

 void PSParallelCompact::marking_phase(ParCompactionManager* cm,

                                       bool maximum_heap_compaction) {

   // Recursively traverse all live objects and mark them

   EventMark m("1 mark object");

   TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);

   ParallelScavengeHeap* heap = gc_heap();

   uint parallel_gc_threads = heap->gc_task_manager()->workers();

   TaskQueueSetSuper* qset = ParCompactionManager::chunk_array();

   ParallelTaskTerminator terminator(parallel_gc_threads, qset);

   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);

   PSParallelCompact::FollowStackClosure follow_stack_closure(cm);

   {

     TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);

     GCTaskQueue* q = GCTaskQueue::create();

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));

     // We scan the thread roots in parallel

     Threads::create_thread_roots_marking_tasks(q);

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));

     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols));

     if (parallel_gc_threads > 1) {

       for (uint j = 0; j < parallel_gc_threads; j++) {

         q->enqueue(new StealMarkingTask(&terminator));

       }

     }

     WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();

     q->enqueue(fin);

     gc_task_manager()->add_list(q);

     fin->wait_for();

     // We have to release the barrier tasks!

     WaitForBarrierGCTask::destroy(fin);

   }

   // Process reference objects found during marking

   {

     TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);

     ReferencePolicy *soft_ref_policy;

     if (maximum_heap_compaction) {

       soft_ref_policy = new AlwaysClearPolicy();

     } else {

 #ifdef COMPILER2

       soft_ref_policy = new LRUMaxHeapPolicy();

 #else

       soft_ref_policy = new LRUCurrentHeapPolicy();

 #endif // COMPILER2

     }

     assert(soft_ref_policy != NULL, "No soft reference policy");

     if (ref_processor()->processing_is_mt()) {

       RefProcTaskExecutor task_executor;

       ref_processor()->process_discovered_references(

         soft_ref_policy, is_alive_closure(), &mark_and_push_closure,

         &follow_stack_closure, &task_executor);

     } else {

       ref_processor()->process_discovered_references(

         soft_ref_policy, is_alive_closure(), &mark_and_push_closure,

         &follow_stack_closure, NULL);

     }

   }

   TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);

   // Follow system dictionary roots and unload classes.

   bool purged_class = SystemDictionary::do_unloading(is_alive_closure());

   // Follow code cache roots.

   CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,

                           purged_class);

   follow_stack(cm); // Flush marking stack.

   // Update subklass/sibling/implementor links of live klasses

   // revisit_klass_stack is used in follow_weak_klass_links().

   follow_weak_klass_links(cm);

   // Visit symbol and interned string tables and delete unmarked oops

   SymbolTable::unlink(is_alive_closure());

   StringTable::unlink(is_alive_closure());

   assert(cm->marking_stack()->size() == 0, "stack should be empty by now");

   assert(cm->overflow_stack()->is_empty(), "stack should be empty by now");

 }

 // This should be moved to the shared markSweep code!

 class PSAlwaysTrueClosure: public BoolObjectClosure {

 public:

   void do_object(oop p) { ShouldNotReachHere(); }

   bool do_object_b(oop p) { return true; }

 };

 static PSAlwaysTrueClosure always_true;

 void PSParallelCompact::adjust_roots() {

   // Adjust the pointers to reflect the new locations

   EventMark m("3 adjust roots");

   TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);

   // General strong roots.

   Universe::oops_do(adjust_root_pointer_closure());

   ReferenceProcessor::oops_do(adjust_root_pointer_closure());

   JNIHandles::oops_do(adjust_root_pointer_closure());   // Global (strong) JNI handles

   Threads::oops_do(adjust_root_pointer_closure());

   ObjectSynchronizer::oops_do(adjust_root_pointer_closure());

   FlatProfiler::oops_do(adjust_root_pointer_closure());

   Management::oops_do(adjust_root_pointer_closure());

   JvmtiExport::oops_do(adjust_root_pointer_closure());

   // SO_AllClasses

   SystemDictionary::oops_do(adjust_root_pointer_closure());

   vmSymbols::oops_do(adjust_root_pointer_closure());

   // Now adjust pointers in remaining weak roots.  (All of which should

   // have been cleared if they pointed to non-surviving objects.)

   // Global (weak) JNI handles

   JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());

   CodeCache::oops_do(adjust_pointer_closure());

   SymbolTable::oops_do(adjust_root_pointer_closure());

   StringTable::oops_do(adjust_root_pointer_closure());

   ref_processor()->weak_oops_do(adjust_root_pointer_closure());

   // Roots were visited so references into the young gen in roots

   // may have been scanned.  Process them also.

   // Should the reference processor have a span that excludes

   // young gen objects?

   PSScavenge::reference_processor()->weak_oops_do(

                                               adjust_root_pointer_closure());

 }

 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {

   EventMark m("4 compact perm");

   TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty);

   // trace("4");

   gc_heap()->perm_gen()->start_array()->reset();

   move_and_update(cm, perm_space_id);

 }

 void PSParallelCompact::enqueue_chunk_draining_tasks(GCTaskQueue* q,

                                                      uint parallel_gc_threads) {

   TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);

   const unsigned int task_count = MAX2(parallel_gc_threads, 1U);

   for (unsigned int j = 0; j < task_count; j++) {

     q->enqueue(new DrainStacksCompactionTask());

   }

   // Find all chunks that are available (can be filled immediately) and

   // distribute them to the thread stacks.  The iteration is done in reverse

   // order (high to low) so the chunks will be removed in ascending order.

   const ParallelCompactData& sd = PSParallelCompact::summary_data();

   size_t fillable_chunks = 0;   // A count for diagnostic purposes.

   unsigned int which = 0;       // The worker thread number.

   for (unsigned int id = to_space_id; id > perm_space_id; --id) {

     SpaceInfo* const space_info = _space_info + id;

     MutableSpace* const space = space_info->space();

     HeapWord* const new_top = space_info->new_top();

     const size_t beg_chunk = sd.addr_to_chunk_idx(space_info->dense_prefix());

     const size_t end_chunk = sd.addr_to_chunk_idx(sd.chunk_align_up(new_top));

     assert(end_chunk > 0, "perm gen cannot be empty");

     for (size_t cur = end_chunk - 1; cur >= beg_chunk; --cur) {

       if (sd.chunk(cur)->claim_unsafe()) {

         ParCompactionManager* cm = ParCompactionManager::manager_array(which);

         cm->save_for_processing(cur);

         if (TraceParallelOldGCCompactionPhase && Verbose) {

           const size_t count_mod_8 = fillable_chunks & 7;

           if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");

           gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);

           if (count_mod_8 == 7) gclog_or_tty->cr();

         }

         NOT_PRODUCT(++fillable_chunks;)

         // Assign chunks to threads in round-robin fashion.

         if (++which == task_count) {

           which = 0;

         }

       }

     }

   }

   if (TraceParallelOldGCCompactionPhase) {

     if (Verbose && (fillable_chunks & 7) != 0) gclog_or_tty->cr();

     gclog_or_tty->print_cr("%u initially fillable chunks", fillable_chunks);

   }

 }

 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4

 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,

                                                     uint parallel_gc_threads) {

   TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);

   ParallelCompactData& sd = PSParallelCompact::summary_data();

   // Iterate over all the spaces adding tasks for updating

   // chunks in the dense prefix.  Assume that 1 gc thread

   // will work on opening the gaps and the remaining gc threads

   // will work on the dense prefix.

   SpaceId space_id = old_space_id;

   while (space_id != last_space_id) {

     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();

     const MutableSpace* const space = _space_info[space_id].space();

     if (dense_prefix_end == space->bottom()) {

       // There is no dense prefix for this space.

       space_id = next_compaction_space_id(space_id);

       continue;

     }

     // The dense prefix is before this chunk.

     size_t chunk_index_end_dense_prefix =

         sd.addr_to_chunk_idx(dense_prefix_end);

     ChunkData* const dense_prefix_cp = sd.chunk(chunk_index_end_dense_prefix);

     assert(dense_prefix_end == space->end() ||

            dense_prefix_cp->available() ||

            dense_prefix_cp->claimed(),

            "The chunk after the dense prefix should always be ready to fill");

     size_t chunk_index_start = sd.addr_to_chunk_idx(space->bottom());

     // Is there dense prefix work?

     size_t total_dense_prefix_chunks =

       chunk_index_end_dense_prefix - chunk_index_start;

     // How many chunks of the dense prefix should be given to

     // each thread?

     if (total_dense_prefix_chunks > 0) {

       uint tasks_for_dense_prefix = 1;

       if (UseParallelDensePrefixUpdate) {

         if (total_dense_prefix_chunks <=

             (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {

           // Don't over partition.  This assumes that

           // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value

           // so there are not many chunks to process.

           tasks_for_dense_prefix = parallel_gc_threads;

         } else {

           // Over partition

           tasks_for_dense_prefix = parallel_gc_threads *

             PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;

         }

       }

       size_t chunks_per_thread = total_dense_prefix_chunks /

         tasks_for_dense_prefix;

       // Give each thread at least 1 chunk.

       if (chunks_per_thread == 0) {

         chunks_per_thread = 1;

       }

       for (uint k = 0; k < tasks_for_dense_prefix; k++) {

         if (chunk_index_start >= chunk_index_end_dense_prefix) {

           break;

         }

         // chunk_index_end is not processed

         size_t chunk_index_end = MIN2(chunk_index_start + chunks_per_thread,

                                       chunk_index_end_dense_prefix);

         q->enqueue(new UpdateDensePrefixTask(

                                  space_id,

                                  chunk_index_start,

                                  chunk_index_end));

         chunk_index_start = chunk_index_end;

       }

     }

     // This gets any part of the dense prefix that did not

     // fit evenly.

     if (chunk_index_start < chunk_index_end_dense_prefix) {

       q->enqueue(new UpdateDensePrefixTask(

                                  space_id,

                                  chunk_index_start,

                                  chunk_index_end_dense_prefix));

     }

     space_id = next_compaction_space_id(space_id);

   }  // End tasks for dense prefix

 }

 void PSParallelCompact::enqueue_chunk_stealing_tasks(

                                      GCTaskQueue* q,

                                      ParallelTaskTerminator* terminator_ptr,

                                      uint parallel_gc_threads) {

   TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);

   // Once a thread has drained it's stack, it should try to steal chunks from

   // other threads.

   if (parallel_gc_threads > 1) {

     for (uint j = 0; j < parallel_gc_threads; j++) {

       q->enqueue(new StealChunkCompactionTask(terminator_ptr));

     }

   }

 }

 void PSParallelCompact::compact() {

   EventMark m("5 compact");

   // trace("5");

   TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   PSOldGen* old_gen = heap->old_gen();

   old_gen->start_array()->reset();

   uint parallel_gc_threads = heap->gc_task_manager()->workers();

   TaskQueueSetSuper* qset = ParCompactionManager::chunk_array();

   ParallelTaskTerminator terminator(parallel_gc_threads, qset);

   GCTaskQueue* q = GCTaskQueue::create();

   enqueue_chunk_draining_tasks(q, parallel_gc_threads);

   enqueue_dense_prefix_tasks(q, parallel_gc_threads);

   enqueue_chunk_stealing_tasks(q, &terminator, parallel_gc_threads);

   {

     TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);

     WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();

     q->enqueue(fin);

     gc_task_manager()->add_list(q);

     fin->wait_for();

     // We have to release the barrier tasks!

     WaitForBarrierGCTask::destroy(fin);

 #ifdef  ASSERT

     // Verify that all chunks have been processed before the deferred updates.

     // Note that perm_space_id is skipped; this type of verification is not

     // valid until the perm gen is compacted by chunks.

     for (unsigned int id = old_space_id; id < last_space_id; ++id) {

       verify_complete(SpaceId(id));

     }

 #endif

   }

   {

     // Update the deferred objects, if any.  Any compaction manager can be used.

     TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);

     ParCompactionManager* cm = ParCompactionManager::manager_array(0);

     for (unsigned int id = old_space_id; id < last_space_id; ++id) {

       update_deferred_objects(cm, SpaceId(id));

     }

   }

 }

 #ifdef  ASSERT

 void PSParallelCompact::verify_complete(SpaceId space_id) {

   // All Chunks between space bottom() to new_top() should be marked as filled

   // and all Chunks between new_top() and top() should be available (i.e.,

   // should have been emptied).

   ParallelCompactData& sd = summary_data();

   SpaceInfo si = _space_info[space_id];

   HeapWord* new_top_addr = sd.chunk_align_up(si.new_top());

   HeapWord* old_top_addr = sd.chunk_align_up(si.space()->top());

   const size_t beg_chunk = sd.addr_to_chunk_idx(si.space()->bottom());

   const size_t new_top_chunk = sd.addr_to_chunk_idx(new_top_addr);

   const size_t old_top_chunk = sd.addr_to_chunk_idx(old_top_addr);

   bool issued_a_warning = false;

   size_t cur_chunk;

   for (cur_chunk = beg_chunk; cur_chunk < new_top_chunk; ++cur_chunk) {

     const ChunkData* const c = sd.chunk(cur_chunk);

     if (!c->completed()) {

       warning("chunk " SIZE_FORMAT " not filled:  "

               "destination_count=" SIZE_FORMAT,

               cur_chunk, c->destination_count());

       issued_a_warning = true;

     }

   }

   for (cur_chunk = new_top_chunk; cur_chunk < old_top_chunk; ++cur_chunk) {

     const ChunkData* const c = sd.chunk(cur_chunk);

     if (!c->available()) {

       warning("chunk " SIZE_FORMAT " not empty:   "

               "destination_count=" SIZE_FORMAT,

               cur_chunk, c->destination_count());

       issued_a_warning = true;

     }

   }

   if (issued_a_warning) {

     print_chunk_ranges();

   }

 }

 #endif  // #ifdef ASSERT

 void PSParallelCompact::compact_serial(ParCompactionManager* cm) {

   EventMark m("5 compact serial");

   TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();

   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   PSYoungGen* young_gen = heap->young_gen();

   PSOldGen* old_gen = heap->old_gen();

   old_gen->start_array()->reset();

   old_gen->move_and_update(cm);

   young_gen->move_and_update(cm);

 }

 void PSParallelCompact::follow_stack(ParCompactionManager* cm) {

   while(!cm->overflow_stack()->is_empty()) {

     oop obj = cm->overflow_stack()->pop();

     obj->follow_contents(cm);

   }

   oop obj;

   // obj is a reference!!!

   while (cm->marking_stack()->pop_local(obj)) {

     // It would be nice to assert about the type of objects we might

     // pop, but they can come from anywhere, unfortunately.

     obj->follow_contents(cm);

   }

 }

 void

 PSParallelCompact::follow_weak_klass_links(ParCompactionManager* serial_cm) {

   // All klasses on the revisit stack are marked at this point.

   // Update and follow all subklass, sibling and implementor links.

   for (uint i = 0; i < ParallelGCThreads+1; i++) {

     ParCompactionManager* cm = ParCompactionManager::manager_array(i);

     KeepAliveClosure keep_alive_closure(cm);

     for (int i = 0; i < cm->revisit_klass_stack()->length(); i++) {

       cm->revisit_klass_stack()->at(i)->follow_weak_klass_links(

         is_alive_closure(),

         &keep_alive_closure);

     }

     follow_stack(cm);

   }

 }

 void

 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {

   cm->revisit_klass_stack()->push(k);