jdk8-mips64-public/hotspot: comparison src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp

--1:000000000000
+:f90c822e73f8
+/*
+* Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*
+*/
+#include "precompiled.hpp"
+#include "classfile/symbolTable.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "code/codeCache.hpp"
+#include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
+#include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"
+#include "gc_implementation/parallelScavenge/pcTasks.hpp"
+#include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
+#include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp"
+#include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
+#include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
+#include "gc_implementation/parallelScavenge/psOldGen.hpp"
+#include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
+#include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
+#include "gc_implementation/parallelScavenge/psScavenge.hpp"
+#include "gc_implementation/parallelScavenge/psYoungGen.hpp"
+#include "gc_implementation/shared/gcHeapSummary.hpp"
+#include "gc_implementation/shared/gcTimer.hpp"
+#include "gc_implementation/shared/gcTrace.hpp"
+#include "gc_implementation/shared/gcTraceTime.hpp"
+#include "gc_implementation/shared/isGCActiveMark.hpp"
+#include "gc_interface/gcCause.hpp"
+#include "memory/gcLocker.inline.hpp"
+#include "memory/referencePolicy.hpp"
+#include "memory/referenceProcessor.hpp"
+#include "oops/methodData.hpp"
+#include "oops/oop.inline.hpp"
+#include "oops/oop.pcgc.inline.hpp"
+#include "runtime/fprofiler.hpp"
+#include "runtime/safepoint.hpp"
+#include "runtime/vmThread.hpp"
+#include "services/management.hpp"
+#include "services/memoryService.hpp"
+#include "services/memTracker.hpp"
+#include "utilities/events.hpp"
+#include "utilities/stack.inline.hpp"
+#include <math.h>
+PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
+// All sizes are in HeapWords.
+const size_t ParallelCompactData::Log2RegionSize  = 16; // 64K words
+const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
+const size_t ParallelCompactData::RegionSizeBytes =
+RegionSize << LogHeapWordSize;
+const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
+const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
+const size_t ParallelCompactData::RegionAddrMask       = ~RegionAddrOffsetMask;
+const size_t ParallelCompactData::Log2BlockSize   = 7; // 128 words
+const size_t ParallelCompactData::BlockSize       = (size_t)1 << Log2BlockSize;
+const size_t ParallelCompactData::BlockSizeBytes  =
+BlockSize << LogHeapWordSize;
+const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
+const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
+const size_t ParallelCompactData::BlockAddrMask       = ~BlockAddrOffsetMask;
+const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
+const size_t ParallelCompactData::Log2BlocksPerRegion =
+Log2RegionSize - Log2BlockSize;
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_shift = 27;
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::los_mask = ~dc_mask;
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
+SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
+bool      PSParallelCompact::_print_phases = false;
+ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
+Klass*              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
+void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
+HeapWord* destination)
+{
+assert(src_region_idx != 0, "invalid src_region_idx");
+assert(partial_obj_size != 0, "invalid partial_obj_size argument");
+assert(destination != NULL, "invalid destination argument");
+_src_region_idx = src_region_idx;
+_partial_obj_size = partial_obj_size;
+_destination = destination;
+// These fields may not be updated below, so make sure they're clear.
+assert(_dest_region_addr == NULL, "should have been cleared");
+assert(_first_src_addr == NULL, "should have been cleared");
+// Determine the number of destination regions for the partial object.
+HeapWord* const last_word = destination + partial_obj_size - 1;
+const ParallelCompactData& sd = PSParallelCompact::summary_data();
+HeapWord* const beg_region_addr = sd.region_align_down(destination);
+HeapWord* const end_region_addr = sd.region_align_down(last_word);
+if (beg_region_addr == end_region_addr) {
+// One destination region.
+_destination_count = 1;
+if (end_region_addr == destination) {
+// The destination falls on a region boundary, thus the first word of the
+// partial object will be the first word copied to the destination region.
+_dest_region_addr = end_region_addr;
+_first_src_addr = sd.region_to_addr(src_region_idx);
+}
+} else {
+// Two destination regions.  When copied, the partial object will cross a
+// destination region boundary, so a word somewhere within the partial
+// object will be the first word copied to the second destination region.
+_destination_count = 2;
+_dest_region_addr = end_region_addr;
+const size_t ofs = pointer_delta(end_region_addr, destination);
+assert(ofs < _partial_obj_size, "sanity");
+_first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
+}
+}
+void SplitInfo::clear()
+{
+_src_region_idx = 0;
+_partial_obj_size = 0;
+_destination = NULL;
+_destination_count = 0;
+_dest_region_addr = NULL;
+_first_src_addr = NULL;
+assert(!is_valid(), "sanity");
+}
+#ifdef  ASSERT
+void SplitInfo::verify_clear()
+{
+assert(_src_region_idx == 0, "not clear");
+assert(_partial_obj_size == 0, "not clear");
+assert(_destination == NULL, "not clear");
+assert(_destination_count == 0, "not clear");
+assert(_dest_region_addr == NULL, "not clear");
+assert(_first_src_addr == NULL, "not clear");
+}
+#endif  // #ifdef ASSERT
+void PSParallelCompact::print_on_error(outputStream* st) {
+_mark_bitmap.print_on_error(st);
+}
+#ifndef PRODUCT
+const char* PSParallelCompact::space_names[] = {
+"old ", "eden", "from", "to  "
+};
+void PSParallelCompact::print_region_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_region_idx(space->bottom()),
+summary_data().addr_to_region_idx(space->top()),
+summary_data().addr_to_region_idx(space->end()),
+summary_data().addr_to_region_idx(_space_info[id].new_top()));
+}
+}
+void
+print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
+{
+#define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
+#define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
+ParallelCompactData& sd = PSParallelCompact::summary_data();
+size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
+tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
+REGION_IDX_FORMAT " " PTR_FORMAT " "
+REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
+REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
+i, c->data_location(), dci, c->destination(),
+c->partial_obj_size(), c->live_obj_size(),
+c->data_size(), c->source_region(), c->destination_count());
+#undef  REGION_IDX_FORMAT
+#undef  REGION_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_region_idx(beg_addr);
+const size_t last = summary_data.addr_to_region_idx(end_addr);
+HeapWord* pdest = 0;
+while (i <= last) {
+ParallelCompactData::RegionData* c = summary_data.region(i);
+if (c->data_size() != 0 || c->destination() != pdest) {
+print_generic_summary_region(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_region(size_t i,
+const ParallelCompactData::RegionData* 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_region(), 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 region_size = ParallelCompactData::RegionSize;
+typedef ParallelCompactData::RegionData RegionData;
+HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
+const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
+const RegionData* c = summary_data.region(end_region - 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 regions at the beginning of the space.
+size_t full_region_count = 0;
+size_t i = summary_data.addr_to_region_idx(space->bottom());
+while (i < end_region && summary_data.region(i)->data_size() == region_size) {
+print_initial_summary_region(i, summary_data.region(i));
+++full_region_count;
+++i;
+}
+size_t live_to_right = live_in_space - full_region_count * region_size;
+double max_reclaimed_ratio = 0.0;
+size_t max_reclaimed_ratio_region = 0;
+size_t max_dead_to_right = 0;
+size_t max_live_to_right = 0;
+// Print the 'reclaimed ratio' for regions while there is something live in
+// the region or to the right of it.  The remaining regions are empty (and
+// uninteresting), and computing the ratio will result in division by 0.
+while (i < end_region && live_to_right > 0) {
+c = summary_data.region(i);
+HeapWord* const region_addr = summary_data.region_to_addr(i);
+const size_t used_to_right = pointer_delta(space->top(), region_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_region = i;
+max_dead_to_right = dead_to_right;
+max_live_to_right = live_to_right;
+}
+print_initial_summary_region(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 regions are empty.  Print one more if there is one.
+if (i < end_region) {
+print_initial_summary_region(i, summary_data.region(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_region, 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::old_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;
+_region_vspace = 0;
+_reserved_byte_size = 0;
+_region_data = 0;
+_region_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(region_align_down(_region_start) == _region_start,
+"region start not aligned");
+assert((region_size & RegionSizeOffsetMask) == 0,
+"region size not a multiple of RegionSize");
+bool result = initialize_region_data(region_size) && initialize_block_data();
+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();
+_reserved_byte_size = 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(_reserved_byte_size, rs_align, rs_align > 0);
+os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
+rs.size());
+MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
+PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
+if (vspace != 0) {
+if (vspace->expand_by(_reserved_byte_size)) {
+return vspace;
+}
+delete vspace;
+// Release memory reserved in the space.
+rs.release();
+}
+return 0;
+}
+bool ParallelCompactData::initialize_region_data(size_t region_size)
+{
+const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
+_region_vspace = create_vspace(count, sizeof(RegionData));
+if (_region_vspace != 0) {
+_region_data = (RegionData*)_region_vspace->reserved_low_addr();
+_region_count = count;
+return true;
+}
+return false;
+}
+bool ParallelCompactData::initialize_block_data()
+{
+assert(_region_count != 0, "region data must be initialized first");
+const size_t count = _region_count << Log2BlocksPerRegion;
+_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()
+{
+memset(_region_data, 0, _region_vspace->committed_size());
+memset(_block_data, 0, _block_vspace->committed_size());
+}
+void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
+assert(beg_region <= _region_count, "beg_region out of range");
+assert(end_region <= _region_count, "end_region out of range");
+assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
+const size_t region_cnt = end_region - beg_region;
+memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
+const size_t beg_block = beg_region * BlocksPerRegion;
+const size_t block_cnt = region_cnt * BlocksPerRegion;
+memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
+}
+HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
+{
+const RegionData* cur_cp = region(region_idx);
+const RegionData* const end_cp = region(region_count() - 1);
+HeapWord* result = region_to_addr(region_idx);
+if (cur_cp < end_cp) {
+do {
+result += cur_cp->partial_obj_size();
+} while (cur_cp->partial_obj_size() == RegionSize && ++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_region = obj_ofs >> Log2RegionSize;
+const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
+DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
+DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
+if (beg_region == end_region) {
+// All in one region.
+_region_data[beg_region].add_live_obj(len);
+return;
+}
+// First region.
+const size_t beg_ofs = region_offset(addr);
+_region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
+Klass* klass = ((oop)addr)->klass();
+// Middle regions--completely spanned by this object.
+for (size_t region = beg_region + 1; region < end_region; ++region) {
+_region_data[region].set_partial_obj_size(RegionSize);
+_region_data[region].set_partial_obj_addr(addr);
+}
+// Last region.
+const size_t end_ofs = region_offset(addr + len - 1);
+_region_data[end_region].set_partial_obj_size(end_ofs + 1);
+_region_data[end_region].set_partial_obj_addr(addr);
+}
+void
+ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
+{
+assert(region_offset(beg) == 0, "not RegionSize aligned");
+assert(region_offset(end) == 0, "not RegionSize aligned");
+size_t cur_region = addr_to_region_idx(beg);
+const size_t end_region = addr_to_region_idx(end);
+HeapWord* addr = beg;
+while (cur_region < end_region) {
+_region_data[cur_region].set_destination(addr);
+_region_data[cur_region].set_destination_count(0);
+_region_data[cur_region].set_source_region(cur_region);
+_region_data[cur_region].set_data_location(addr);
+// Update live_obj_size so the region appears completely full.
+size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
+_region_data[cur_region].set_live_obj_size(live_size);
+++cur_region;
+addr += RegionSize;
+}
+}
+// Find the point at which a space can be split and, if necessary, record the
+// split point.
+//
+// If the current src region (which overflowed the destination space) doesn't
+// have a partial object, the split point is at the beginning of the current src
+// region (an "easy" split, no extra bookkeeping required).
+//
+// If the current src region has a partial object, the split point is in the
+// region where that partial object starts (call it the split_region).  If
+// split_region has a partial object, then the split point is just after that
+// partial object (a "hard" split where we have to record the split data and
+// zero the partial_obj_size field).  With a "hard" split, we know that the
+// partial_obj ends within split_region because the partial object that caused
+// the overflow starts in split_region.  If split_region doesn't have a partial
+// obj, then the split is at the beginning of split_region (another "easy"
+// split).
+HeapWord*
+ParallelCompactData::summarize_split_space(size_t src_region,
+SplitInfo& split_info,
+HeapWord* destination,
+HeapWord* target_end,
+HeapWord** target_next)
+{
+assert(destination <= target_end, "sanity");
+assert(destination + _region_data[src_region].data_size() > target_end,
+"region should not fit into target space");
+assert(is_region_aligned(target_end), "sanity");
+size_t split_region = src_region;
+HeapWord* split_destination = destination;
+size_t partial_obj_size = _region_data[src_region].partial_obj_size();
+if (destination + partial_obj_size > target_end) {
+// The split point is just after the partial object (if any) in the
+// src_region that contains the start of the object that overflowed the
+// destination space.
+//
+// Find the start of the "overflow" object and set split_region to the
+// region containing it.
+HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
+split_region = addr_to_region_idx(overflow_obj);
+// Clear the source_region field of all destination regions whose first word
+// came from data after the split point (a non-null source_region field
+// implies a region must be filled).
+//
+// An alternative to the simple loop below:  clear during post_compact(),
+// which uses memcpy instead of individual stores, and is easy to
+// parallelize.  (The downside is that it clears the entire RegionData
+// object as opposed to just one field.)
+//
+// post_compact() would have to clear the summary data up to the highest
+// address that was written during the summary phase, which would be
+//
+//         max(top, max(new_top, clear_top))
+//
+// where clear_top is a new field in SpaceInfo.  Would have to set clear_top
+// to target_end.
+const RegionData* const sr = region(split_region);
+const size_t beg_idx =
+addr_to_region_idx(region_align_up(sr->destination() +
+sr->partial_obj_size()));
+const size_t end_idx = addr_to_region_idx(target_end);
+if (TraceParallelOldGCSummaryPhase) {
+gclog_or_tty->print_cr("split:  clearing source_region field in ["
+SIZE_FORMAT ", " SIZE_FORMAT ")",
+beg_idx, end_idx);
+}
+for (size_t idx = beg_idx; idx < end_idx; ++idx) {
+_region_data[idx].set_source_region(0);
+}
+// Set split_destination and partial_obj_size to reflect the split region.
+split_destination = sr->destination();
+partial_obj_size = sr->partial_obj_size();
+}
+// The split is recorded only if a partial object extends onto the region.
+if (partial_obj_size != 0) {
+_region_data[split_region].set_partial_obj_size(0);
+split_info.record(split_region, partial_obj_size, split_destination);
+}
+// Setup the continuation addresses.
+*target_next = split_destination + partial_obj_size;
+HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
+if (TraceParallelOldGCSummaryPhase) {
+const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
+gclog_or_tty->print_cr("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT
+" pos=" SIZE_FORMAT,
+split_type, source_next, split_region,
+partial_obj_size);
+gclog_or_tty->print_cr("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
+" tn=" PTR_FORMAT,
+split_type, split_destination,
+addr_to_region_idx(split_destination),
+*target_next);
+if (partial_obj_size != 0) {
+HeapWord* const po_beg = split_info.destination();
+HeapWord* const po_end = po_beg + split_info.partial_obj_size();
+gclog_or_tty->print_cr("%s split:  "
+"po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
+"po_end=" PTR_FORMAT " " SIZE_FORMAT,
+split_type,
+po_beg, addr_to_region_idx(po_beg),
+po_end, addr_to_region_idx(po_end));
+}
+}
+return source_next;
+}
+bool ParallelCompactData::summarize(SplitInfo& split_info,
+HeapWord* source_beg, HeapWord* source_end,
+HeapWord** source_next,
+HeapWord* target_beg, HeapWord* target_end,
+HeapWord** target_next)
+{
+if (TraceParallelOldGCSummaryPhase) {
+HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
+tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
+"tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
+source_beg, source_end, source_next_val,
+target_beg, target_end, *target_next);
+}
+size_t cur_region = addr_to_region_idx(source_beg);
+const size_t end_region = addr_to_region_idx(region_align_up(source_end));
+HeapWord *dest_addr = target_beg;
+while (cur_region < end_region) {
+// The destination must be set even if the region has no data.
+_region_data[cur_region].set_destination(dest_addr);
+size_t words = _region_data[cur_region].data_size();
+if (words > 0) {
+// If cur_region does not fit entirely into the target space, find a point
+// at which the source space can be 'split' so that part is copied to the
+// target space and the rest is copied elsewhere.
+if (dest_addr + words > target_end) {
+assert(source_next != NULL, "source_next is NULL when splitting");
+*source_next = summarize_split_space(cur_region, split_info, dest_addr,
+target_end, target_next);
+return false;
+}
+// Compute the destination_count for cur_region, and if necessary, update
+// source_region for a destination region.  The source_region field is
+// updated if cur_region is the first (left-most) region to be copied to a
+// destination region.
+//
+// The destination_count calculation is a bit subtle.  A region that has
+// data that compacts into itself does not count itself as a destination.
+// This maintains the invariant that a zero count means the region is
+// available and can be claimed and then filled.
+uint destination_count = 0;
+if (split_info.is_split(cur_region)) {
+// The current region has been split:  the partial object will be copied
+// to one destination space and the remaining data will be copied to
+// another destination space.  Adjust the initial destination_count and,
+// if necessary, set the source_region field if the partial object will
+// cross a destination region boundary.
+destination_count = split_info.destination_count();
+if (destination_count == 2) {
+size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
+_region_data[dest_idx].set_source_region(cur_region);
+}
+}
+HeapWord* const last_addr = dest_addr + words - 1;
+const size_t dest_region_1 = addr_to_region_idx(dest_addr);
+const size_t dest_region_2 = addr_to_region_idx(last_addr);
+// Initially assume that the destination regions will be the same and
+// adjust the value below if necessary.  Under this assumption, if
+// cur_region == dest_region_2, then cur_region will be compacted
+// completely into itself.
+destination_count += cur_region == dest_region_2 ? 0 : 1;
+if (dest_region_1 != dest_region_2) {
+// Destination regions differ; adjust destination_count.
+destination_count += 1;
+// Data from cur_region will be copied to the start of dest_region_2.
+_region_data[dest_region_2].set_source_region(cur_region);
+} else if (region_offset(dest_addr) == 0) {
+// Data from cur_region will be copied to the start of the destination
+// region.
+_region_data[dest_region_1].set_source_region(cur_region);
+}
+_region_data[cur_region].set_destination_count(destination_count);
+_region_data[cur_region].set_data_location(region_to_addr(cur_region));
+dest_addr += words;
+}
+++cur_region;
+}
+*target_next = dest_addr;
+return true;
+}
+HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
+assert(addr != NULL, "Should detect NULL oop earlier");
+assert(PSParallelCompact::gc_heap()->is_in(addr), "not in heap");
+assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
+// Region covering the object.
+RegionData* const region_ptr = addr_to_region_ptr(addr);
+HeapWord* result = region_ptr->destination();
+// If the entire Region is live, the new location is region->destination + the
+// offset of the object within in the Region.
+// Run some performance tests to determine if this special case pays off.  It
+// is worth it for pointers into the dense prefix.  If the optimization to
+// avoid pointer updates in regions that only point to the dense prefix is
+// ever implemented, this should be revisited.
+if (region_ptr->data_size() == RegionSize) {
+result += region_offset(addr);
+return result;
+}
+// Otherwise, the new location is region->destination + block offset + the
+// number of live words in the Block that are (a) to the left of addr and (b)
+// due to objects that start in the Block.
+// Fill in the block table if necessary.  This is unsynchronized, so multiple
+// threads may fill the block table for a region (harmless, since it is
+// idempotent).
+if (!region_ptr->blocks_filled()) {
+PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
+region_ptr->set_blocks_filled();
+}
+HeapWord* const search_start = block_align_down(addr);
+const size_t block_offset = addr_to_block_ptr(addr)->offset();
+const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
+const size_t live = bitmap->live_words_in_range(search_start, oop(addr));
+result += block_offset + live;
+DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
+return result;
+}
+#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(_region_vspace);
+verify_clear(_block_vspace);
+}
+#endif  // #ifdef ASSERT
+STWGCTimer          PSParallelCompact::_gc_timer;
+ParallelOldTracer   PSParallelCompact::_gc_tracer;
+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;
+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_pointer_closure;
+PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
+void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p)       { adjust_pointer(p); }
+void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p); }
+void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
+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::FollowKlassClosure::do_klass(Klass* klass) {
+klass->oops_do(_mark_and_push_closure);
+}
+void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
+klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
+}
+void PSParallelCompact::post_initialize() {
+ParallelScavengeHeap* heap = gc_heap();
+assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
+MemRegion mr = heap->reserved_region();
+_ref_processor =
+new ReferenceProcessor(mr,            // span
+ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
+(int) ParallelGCThreads, // mt processing degree
+true,          // mt discovery
+(int) ParallelGCThreads, // mt discovery degree
+true,          // atomic_discovery
+&_is_alive_closure); // non-header is alive closure
+_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(
+err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
+"garbage collection for the requested " SIZE_FORMAT "KB heap.",
+_mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
+return false;
+}
+if (!_summary_data.initialize(mr)) {
+vm_shutdown_during_initialization(
+err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
+"garbage collection for the requested " SIZE_FORMAT "KB heap.",
+_summary_data.reserved_byte_size()/K, mr.byte_size()/K));
+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();
+_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[old_space_id].set_start_array(heap->old_gen()->start_array());
+}
+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();
+_metadata_used  = MetaspaceAux::used_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 metadata_used() const  { return _metadata_used; }
+private:
+size_t _heap_used;
+size_t _young_gen_used;
+size_t _old_gen_used;
+size_t _metadata_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_region = _summary_data.addr_to_region_idx(bot);
+const size_t end_region =
+_summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
+_summary_data.clear_range(beg_region, end_region);
+// Clear the data used to 'split' regions.
+SplitInfo& split_info = _space_info[id].split_info();
+if (split_info.is_valid()) {
+split_info.clear();
+}
+DEBUG_ONLY(split_info.verify_clear();)
+}
+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.
+GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer);
+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);
+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++;
+heap->print_heap_before_gc();
+heap->trace_heap_before_gc(&_gc_tracer);
+// 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
+Universe::verify(" VerifyBeforeGC:");
+}
+// Verify object start arrays
+if (VerifyObjectStartArray &&
+VerifyBeforeGC) {
+heap->old_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()
+{
+GCTraceTime tm("post compact", print_phases(), true, &_gc_timer);
+for (unsigned int id = old_space_id; id < last_space_id; ++id) {
+// Clear the marking bitmap, summary data and split info.
+clear_data_covering_space(SpaceId(id));
+// Update top().  Must be done after clearing the bitmap and summary data.
+_space_info[id].publish_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();
+if (young_gen_empty) {
+modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
+} else {
+modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
+}
+}
+// Delete metaspaces for unloaded class loaders and clean up loader_data graph
+ClassLoaderDataGraph::purge();
+MetaspaceAux::verify_metrics();
+Threads::gc_epilogue();
+CodeCache::gc_epilogue();
+JvmtiExport::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 region_size = ParallelCompactData::RegionSize;
+const ParallelCompactData& sd = summary_data();
+const MutableSpace* const space = _space_info[id].space();
+HeapWord* const top_aligned_up = sd.region_align_up(space->top());
+const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
+const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
+// Skip full regions at the beginning of the space--they are necessarily part
+// of the dense prefix.
+size_t full_count = 0;
+const RegionData* cp;
+for (cp = beg_cp; cp < end_cp && cp->data_size() == region_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.region_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.region_to_addr(cp);
+const RegionData* full_cp = cp;
+const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
+while (cp < end_cp) {
+HeapWord* region_destination = cp->destination();
+const size_t cur_deadwood = pointer_delta(dense_prefix, region_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.region(cp), region_destination,
+dense_prefix, cur_deadwood);
+}
+if (cur_deadwood >= deadwood_goal) {
+// Found the region that has the correct amount of deadwood to the left.
+// This typically occurs after crossing a fairly sparse set of regions, so
+// iterate backwards over those sparse regions, looking for the region
+// that has the lowest density of live objects 'to the right.'
+size_t space_to_left = sd.region(cp) * region_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_region_live_to_right = live_to_right -
+cp->data_size();
+const size_t prev_region_space_to_right = space_to_right + region_size;
+double prev_region_density_to_right =
+double(prev_region_live_to_right) / prev_region_space_to_right;
+if (density_to_right <= prev_region_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.region(cp), density_to_right,
+prev_region_density_to_right);
+}
+dense_prefix -= region_size;
+live_to_right = prev_region_live_to_right;
+space_to_right = prev_region_space_to_right;
+density_to_right = prev_region_density_to_right;
+}
+return dense_prefix;
+}
+dense_prefix += region_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 region_idx = summary_data().addr_to_region_idx(addr);
+RegionData* const cp = summary_data().region(region_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, region_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::RegionData*
+PSParallelCompact::first_dead_space_region(const RegionData* beg,
+const RegionData* end)
+{
+const size_t region_size = ParallelCompactData::RegionSize;
+ParallelCompactData& sd = summary_data();
+size_t left = sd.region(beg);
+size_t right = end > beg ? sd.region(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;
+RegionData* const middle_ptr = sd.region(middle);
+HeapWord* const dest = middle_ptr->destination();
+HeapWord* const addr = sd.region_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() == region_size) {
+left = middle + 1;
+} else {
+return middle_ptr;
+}
+}
+return sd.region(left);
+}
+ParallelCompactData::RegionData*
+PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
+const RegionData* end,
+size_t dead_words)
+{
+ParallelCompactData& sd = summary_data();
+size_t left = sd.region(beg);
+size_t right = end > beg ? sd.region(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;
+RegionData* const middle_ptr = sd.region(middle);
+HeapWord* const dest = middle_ptr->destination();
+HeapWord* const addr = sd.region_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.region(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 RegionData* 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.region_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.region_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 region boundary.
+//
+// Completely full regions at the left are skipped, since no compaction can
+// occur in those regions.  Then the maximum amount of dead wood to allow is
+// computed, based on the density (amount live / capacity) of the generation;
+// the region with approximately that amount of dead space to the left is
+// identified as the limit region.  Regions between the last completely full
+// region and the limit region 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)
+{
+if (ParallelOldGCSplitALot) {
+if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
+// The value was chosen to provoke splitting a young gen space; use it.
+return _space_info[id].dense_prefix();
+}
+}
+const size_t region_size = ParallelCompactData::RegionSize;
+const ParallelCompactData& sd = summary_data();
+const MutableSpace* const space = _space_info[id].space();
+HeapWord* const top = space->top();
+HeapWord* const top_aligned_up = sd.region_align_up(top);
+HeapWord* const new_top = _space_info[id].new_top();
+HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
+HeapWord* const bottom = space->bottom();
+const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
+const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
+const RegionData* const new_top_cp =
+sd.addr_to_region_ptr(new_top_aligned_up);
+// Skip full regions at the beginning of the space--they are necessarily part
+// of the dense prefix.
+const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
+assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
+space->is_empty(), "no dead space allowed to the left");
+assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
+"region 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.region_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 = 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 region with the desired amount of dead space to the left.
+const RegionData* const limit_cp =
+dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
+// Scan from the first region with dead space to the limit region and find the
+// one with the best (largest) reclaimed ratio.
+double best_ratio = 0.0;
+const RegionData* best_cp = full_cp;
+for (const RegionData* 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 region with the best ratio is 'close to' the
+// first region w/free space, choose the first region with free space
+// ("first-free").  The first-free region 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(RegionData)) < 4) {
+_maximum_compaction_gc_num = total_invocations();
+best_cp = full_cp;
+}
+#endif  // #if 0
+return sd.region_to_addr(best_cp);
+}
+#ifndef PRODUCT
+void
+PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
+size_t words)
+{
+if (TraceParallelOldGCSummaryPhase) {
+tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
+SIZE_FORMAT, start, start + words, words);
+}
+ObjectStartArray* const start_array = _space_info[id].start_array();
+CollectedHeap::fill_with_objects(start, words);
+for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
+_mark_bitmap.mark_obj(p, words);
+_summary_data.add_obj(p, words);
+start_array->allocate_block(p);
+}
+}
+void
+PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
+{
+ParallelCompactData& sd = summary_data();
+MutableSpace* space = _space_info[id].space();
+// Find the source and destination start addresses.
+HeapWord* const src_addr = sd.region_align_down(start);
+HeapWord* dst_addr;
+if (src_addr < start) {
+dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
+} else if (src_addr > space->bottom()) {
+// The start (the original top() value) is aligned to a region boundary so
+// the associated region does not have a destination.  Compute the
+// destination from the previous region.
+RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
+dst_addr = cp->destination() + cp->data_size();
+} else {
+// Filling the entire space.
+dst_addr = space->bottom();
+}
+assert(dst_addr != NULL, "sanity");
+// Update the summary data.
+bool result = _summary_data.summarize(_space_info[id].split_info(),
+src_addr, space->top(), NULL,
+dst_addr, space->end(),
+_space_info[id].new_top_addr());
+assert(result, "should not fail:  bad filler object size");
+}
+void
+PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
+{
+if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
+return;
+}
+MutableSpace* const space = _space_info[id].space();
+if (space->is_empty()) {
+HeapWord* b = space->bottom();
+HeapWord* t = b + space->capacity_in_words() / 2;
+space->set_top(t);
+if (ZapUnusedHeapArea) {
+space->set_top_for_allocations();
+}
+size_t min_size = CollectedHeap::min_fill_size();
+size_t obj_len = min_size;
+while (b + obj_len <= t) {
+CollectedHeap::fill_with_object(b, obj_len);
+mark_bitmap()->mark_obj(b, obj_len);
+summary_data().add_obj(b, obj_len);
+b += obj_len;
+obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
+}
+if (b < t) {
+// The loop didn't completely fill to t (top); adjust top downward.
+space->set_top(b);
+if (ZapUnusedHeapArea) {
+space->set_top_for_allocations();
+}
+}
+HeapWord** nta = _space_info[id].new_top_addr();
+bool result = summary_data().summarize(_space_info[id].split_info(),
+space->bottom(), space->top(), NULL,
+space->bottom(), space->end(), nta);
+assert(result, "space must fit into itself");
+}
+}
+void
+PSParallelCompact::provoke_split(bool & max_compaction)
+{
+if (total_invocations() % ParallelOldGCSplitInterval != 0) {
+return;
+}
+const size_t region_size = ParallelCompactData::RegionSize;
+ParallelCompactData& sd = summary_data();
+MutableSpace* const eden_space = _space_info[eden_space_id].space();
+MutableSpace* const from_space = _space_info[from_space_id].space();
+const size_t eden_live = pointer_delta(eden_space->top(),
+_space_info[eden_space_id].new_top());
+const size_t from_live = pointer_delta(from_space->top(),
+_space_info[from_space_id].new_top());
+const size_t min_fill_size = CollectedHeap::min_fill_size();
+const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
+const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
+const size_t from_free = pointer_delta(from_space->end(), from_space->top());
+const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
+// Choose the space to split; need at least 2 regions live (or fillable).
+SpaceId id;
+MutableSpace* space;
+size_t live_words;
+size_t fill_words;
+if (eden_live + eden_fillable >= region_size * 2) {
+id = eden_space_id;
+space = eden_space;
+live_words = eden_live;
+fill_words = eden_fillable;
+} else if (from_live + from_fillable >= region_size * 2) {
+id = from_space_id;
+space = from_space;
+live_words = from_live;
+fill_words = from_fillable;
+} else {
+return; // Give up.
+}
+assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
+if (live_words < region_size * 2) {
+// Fill from top() to end() w/live objects of mixed sizes.
+HeapWord* const fill_start = space->top();
+live_words += fill_words;
+space->set_top(fill_start + fill_words);
+if (ZapUnusedHeapArea) {
+space->set_top_for_allocations();
+}
+HeapWord* cur_addr = fill_start;
+while (fill_words > 0) {
+const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
+size_t cur_size = MIN2(align_object_size_(r), fill_words);
+if (fill_words - cur_size < min_fill_size) {
+cur_size = fill_words; // Avoid leaving a fragment too small to fill.
+}
+CollectedHeap::fill_with_object(cur_addr, cur_size);
+mark_bitmap()->mark_obj(cur_addr, cur_size);
+sd.add_obj(cur_addr, cur_size);
+cur_addr += cur_size;
+fill_words -= cur_size;
+}
+summarize_new_objects(id, fill_start);
+}
+max_compaction = false;
+// Manipulate the old gen so that it has room for about half of the live data
+// in the target young gen space (live_words / 2).
+id = old_space_id;
+space = _space_info[id].space();
+const size_t free_at_end = space->free_in_words();
+const size_t free_target = align_object_size(live_words / 2);
+const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
+if (free_at_end >= free_target + min_fill_size) {
+// Fill space above top() and set the dense prefix so everything survives.
+HeapWord* const fill_start = space->top();
+const size_t fill_size = free_at_end - free_target;
+space->set_top(space->top() + fill_size);
+if (ZapUnusedHeapArea) {
+space->set_top_for_allocations();
+}
+fill_with_live_objects(id, fill_start, fill_size);
+summarize_new_objects(id, fill_start);
+_space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
+} else if (dead + free_at_end > free_target) {
+// Find a dense prefix that makes the right amount of space available.
+HeapWord* cur = sd.region_align_down(space->top());
+HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
+size_t dead_to_right = pointer_delta(space->end(), cur_destination);
+while (dead_to_right < free_target) {
+cur -= region_size;
+cur_destination = sd.addr_to_region_ptr(cur)->destination();
+dead_to_right = pointer_delta(space->end(), cur_destination);
+}
+_space_info[id].set_dense_prefix(cur);
+}
+}
+#endif // #ifndef PRODUCT
+void PSParallelCompact::summarize_spaces_quick()
+{
+for (unsigned int i = 0; i < last_space_id; ++i) {
+const MutableSpace* space = _space_info[i].space();
+HeapWord** nta = _space_info[i].new_top_addr();
+bool result = _summary_data.summarize(_space_info[i].split_info(),
+space->bottom(), space->top(), NULL,
+space->bottom(), space->end(), nta);
+assert(result, "space must fit into itself");
+_space_info[i].set_dense_prefix(space->bottom());
+}
+#ifndef PRODUCT
+if (ParallelOldGCSplitALot) {
+provoke_split_fill_survivor(to_space_id);
+}
+#endif // #ifndef PRODUCT
+}
+void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
+{
+HeapWord* const dense_prefix_end = dense_prefix(id);
+const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
+const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
+if (dead_space_crosses_boundary(region, 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 = CollectedHeap::min_fill_size();
+HeapWord* obj_beg = dense_prefix_end - obj_len;
+#ifdef  _LP64
+if (MinObjAlignment > 1) { // object alignment > heap word size
+// Cases a, c or e.
+} else 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
+CollectedHeap::fill_with_object(obj_beg, obj_len);
+_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::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
+{
+RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
+HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
+RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
+for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
+cur->set_source_region(0);
+}
+}
+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() ||
+ParallelOldGCSplitALot && id == old_space_id,
+"should have been reset 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
+// Recompute the summary data, taking into account the dense prefix.  If
+// every last byte will be reclaimed, then the existing summary data which
+// compacts everything can be left in place.
+if (!maximum_compaction && dense_prefix_end != space->bottom()) {
+// 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.
+fill_dense_prefix_end(id);
+// Compute the destination of each Region, and thus each object.
+_summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
+_summary_data.summarize(_space_info[id].split_info(),
+dense_prefix_end, space->top(), NULL,
+dense_prefix_end, space->end(),
+_space_info[id].new_top_addr());
+}
+}
+if (TraceParallelOldGCSummaryPhase) {
+const size_t region_size = ParallelCompactData::RegionSize;
+HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
+const size_t dp_region = _summary_data.addr_to_region_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.region_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_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
+"cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
+id, space->capacity_in_words(), dense_prefix_end,
+dp_region, dp_words / region_size,
+cr_words / region_size, new_top);
+}
+}
+#ifndef PRODUCT
+void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
+HeapWord* dst_beg, HeapWord* dst_end,
+SpaceId src_space_id,
+HeapWord* src_beg, HeapWord* src_end)
+{
+if (TraceParallelOldGCSummaryPhase) {
+tty->print_cr("summarizing %d [%s] into %d [%s]:  "
+"src=" PTR_FORMAT "-" PTR_FORMAT " "
+SIZE_FORMAT "-" SIZE_FORMAT " "
+"dst=" PTR_FORMAT "-" PTR_FORMAT " "
+SIZE_FORMAT "-" SIZE_FORMAT,
+src_space_id, space_names[src_space_id],
+dst_space_id, space_names[dst_space_id],
+src_beg, src_end,
+_summary_data.addr_to_region_idx(src_beg),
+_summary_data.addr_to_region_idx(src_end),
+dst_beg, dst_end,
+_summary_data.addr_to_region_idx(dst_beg),
+_summary_data.addr_to_region_idx(dst_end));
+}
+}
+#endif  // #ifndef PRODUCT
+void PSParallelCompact::summary_phase(ParCompactionManager* cm,
+bool maximum_compaction)
+{
+GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer);
+// 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_region_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;
+for (unsigned int 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());
+}
+MutableSpace* const old_space = _space_info[old_space_id].space();
+const size_t old_capacity = old_space->capacity_in_words();
+if (old_space_total_live > old_capacity) {
+// XXX - should also try to expand
+maximum_compaction = true;
+}
+#ifndef PRODUCT
+if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
+provoke_split(maximum_compaction);
+}
+#endif // #ifndef PRODUCT
+// Old generations.
+summarize_space(old_space_id, maximum_compaction);
+// Summarize the remaining spaces in the young gen.  The initial target space
+// is the old gen.  If a space does not fit entirely into the target, then the
+// remainder is compacted into the space itself and that space becomes the new
+// target.
+SpaceId dst_space_id = old_space_id;
+HeapWord* dst_space_end = old_space->end();
+HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
+for (unsigned int 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(dst_space_end, *new_top_addr);
+NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
+SpaceId(id), space->bottom(), space->top());)
+if (live > 0 && live <= available) {
+// All the live data will fit.
+bool done = _summary_data.summarize(_space_info[id].split_info(),
+space->bottom(), space->top(),
+NULL,
+*new_top_addr, dst_space_end,
+new_top_addr);
+assert(done, "space must fit into old gen");
+// Reset the new_top value for the space.
+_space_info[id].set_new_top(space->bottom());
+} else if (live > 0) {
+// Attempt to fit part of the source space into the target space.
+HeapWord* next_src_addr = NULL;
+bool done = _summary_data.summarize(_space_info[id].split_info(),
+space->bottom(), space->top(),
+&next_src_addr,
+*new_top_addr, dst_space_end,
+new_top_addr);
+assert(!done, "space should not fit into old gen");
+assert(next_src_addr != NULL, "sanity");
+// The source space becomes the new target, so the remainder is compacted
+// within the space itself.
+dst_space_id = SpaceId(id);
+dst_space_end = space->end();
+new_top_addr = _space_info[id].new_top_addr();
+NOT_PRODUCT(summary_phase_msg(dst_space_id,
+space->bottom(), dst_space_end,
+SpaceId(id), next_src_addr, space->top());)
+done = _summary_data.summarize(_space_info[id].split_info(),
+next_src_addr, space->top(),
+NULL,
+space->bottom(), dst_space_end,
+new_top_addr);
+assert(done, "space must fit when compacted into itself");
+assert(*new_top_addr <= space->top(), "usage should not grow");
+}
+}
+if (TraceParallelOldGCSummaryPhase) {
+tty->print_cr("summary_phase:  after final summarization");
+Universe::print();
+NOT_PRODUCT(print_region_ranges());
+if (Verbose) {
+NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
+}
+}
+}
+// 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.
+//
+// Note that the all_soft_refs_clear flag in the collector policy
+// may be true because this method can be called without intervening
+// activity.  For example when the heap space is tight and full measure
+// are being taken to free space.
+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();
+IsGCActiveMark mark;
+if (ScavengeBeforeFullGC) {
+PSScavenge::invoke_no_policy();
+}
+const bool clear_all_soft_refs =
+heap->collector_policy()->should_clear_all_soft_refs();
+PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
+maximum_heap_compaction);
+}
+// This method contains no policy. You should probably
+// be calling invoke() instead.
+bool 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 false;
+}
+ParallelScavengeHeap* heap = gc_heap();
+_gc_timer.register_gc_start();
+_gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
+TimeStamp marking_start;
+TimeStamp compaction_start;
+TimeStamp collection_exit;
+GCCause::Cause gc_cause = heap->gc_cause();
+PSYoungGen* young_gen = heap->young_gen();
+PSOldGen* old_gen = heap->old_gen();
+PSAdaptiveSizePolicy* size_policy = heap->size_policy();
+// The scope of casr should end after code that can change
+// CollectorPolicy::_should_clear_all_soft_refs.
+ClearedAllSoftRefs casr(maximum_heap_compaction,
+heap->collector_policy());
+if (ZapUnusedHeapArea) {
+// Save information needed to minimize mangling
+heap->record_gen_tops_before_GC();
+}
+heap->pre_full_gc_dump(&_gc_timer);
+_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;
+// Set the number of GC threads to be used in this collection
+gc_task_manager()->set_active_gang();
+gc_task_manager()->task_idle_workers();
+heap->set_par_threads(gc_task_manager()->active_workers());
+gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
+TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
+GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
+TraceCollectorStats tcs(counters());
+TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
+if (TraceGen1Time) accumulated_time()->start();
+// Let the size policy know we're starting
+size_policy->major_collection_begin();
+CodeCache::gc_prologue();
+Threads::gc_prologue();
+COMPILER2_PRESENT(DerivedPointerTable::clear());
+ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
+ref_processor()->setup_policy(maximum_heap_compaction);
+bool marked_for_unloading = false;
+marking_start.update();
+marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
+bool max_on_system_gc = UseMaximumCompactionOnSystemGC
+&& gc_cause == GCCause::_java_lang_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();
+compact();
+// 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",
+old_gen->capacity_in_bytes(), young_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 young_live = young_gen->used_in_bytes();
+size_t eden_live = young_gen->eden_space()->used_in_bytes();
+size_t old_live = old_gen->used_in_bytes();
+size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
+size_t max_old_gen_size = old_gen->max_gen_size();
+size_t max_eden_size = young_gen->max_size() -
+young_gen->from_space()->capacity_in_bytes() -
+young_gen->to_space()->capacity_in_bytes();
+// Used for diagnostics
+size_policy->clear_generation_free_space_flags();
+size_policy->compute_generations_free_space(young_live,
+eden_live,
+old_live,
+cur_eden,
+max_old_gen_size,
+max_eden_size,
+true /* full gc*/);
+size_policy->check_gc_overhead_limit(young_live,
+eden_live,
+max_old_gen_size,
+max_eden_size,
+true /* full gc*/,
+gc_cause,
+heap->collector_policy());
+size_policy->decay_supplemental_growth(true /* full gc*/);
+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();
+// Resize the metaspace capactiy after a collection
+MetaspaceGC::compute_new_size();
+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());
+MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_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();
+gc_task_manager()->release_idle_workers();
+}
+#ifdef ASSERT
+for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
+ParCompactionManager* const cm =
+ParCompactionManager::manager_array(int(i));
+assert(cm->marking_stack()->is_empty(),       "should be empty");
+assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
+}
+#endif // ASSERT
+if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
+HandleMark hm;  // Discard invalid handles created during verification
+Universe::verify(" VerifyAfterGC:");
+}
+// Re-verify object start arrays
+if (VerifyObjectStartArray &&
+VerifyAfterGC) {
+old_gen->verify_object_start_array();
+}
+if (ZapUnusedHeapArea) {
+old_gen->object_space()->check_mangled_unused_area_complete();
+}
+NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
+collection_exit.update();
+heap->print_heap_after_gc();
+heap->trace_heap_after_gc(&_gc_tracer);
+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();
+}
+heap->post_full_gc_dump(&_gc_timer);
+#ifdef TRACESPINNING
+ParallelTaskTerminator::print_termination_counts();
+#endif
+_gc_timer.register_gc_end();
+_gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
+_gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
+return true;
+}
+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();
+HeapWord* const unused_start = old_space->top();
+size_t const unused_words = pointer_delta(old_space->end(), unused_start);
+if (unused_words > 0) {
+if (unused_words < CollectedHeap::min_fill_size()) {
+return false;  // If the old gen cannot be filled, must give up.
+}
+CollectedHeap::fill_with_objects(unused_start, unused_words);
+}
+// 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();
+for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
+start_array->allocate_block(p);
+}
+// 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,
+ParallelOldTracer *gc_tracer) {
+// Recursively traverse all live objects and mark them
+GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer);
+ParallelScavengeHeap* heap = gc_heap();
+uint parallel_gc_threads = heap->gc_task_manager()->workers();
+uint active_gc_threads = heap->gc_task_manager()->active_workers();
+TaskQueueSetSuper* qset = ParCompactionManager::region_array();
+ParallelTaskTerminator terminator(active_gc_threads, qset);
+PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
+PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
+// Need new claim bits before marking starts.
+ClassLoaderDataGraph::clear_claimed_marks();
+{
+GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer);
+ParallelScavengeHeap::ParStrongRootsScope psrs;
+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::class_loader_data));
+q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
+q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
+if (active_gc_threads > 1) {
+for (uint j = 0; j < active_gc_threads; j++) {
+q->enqueue(new StealMarkingTask(&terminator));
+}
+}
+gc_task_manager()->execute_and_wait(q);
+}
+// Process reference objects found during marking
+{
+GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer);
+ReferenceProcessorStats stats;
+if (ref_processor()->processing_is_mt()) {
+RefProcTaskExecutor task_executor;
+stats = ref_processor()->process_discovered_references(
+is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
+&task_executor, &_gc_timer);
+} else {
+stats = ref_processor()->process_discovered_references(
+is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
+&_gc_timer);
+}
+gc_tracer->report_gc_reference_stats(stats);
+}
+GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer);
+// This is the point where the entire marking should have completed.
+assert(cm->marking_stacks_empty(), "Marking should have completed");
+// Follow system dictionary roots and unload classes.
+bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
+// Unload nmethods.
+CodeCache::do_unloading(is_alive_closure(), purged_class);
+// Prune dead klasses from subklass/sibling/implementor lists.
+Klass::clean_weak_klass_links(is_alive_closure());
+// Delete entries for dead interned strings.
+StringTable::unlink(is_alive_closure());
+// Clean up unreferenced symbols in symbol table.
+SymbolTable::unlink();
+_gc_tracer.report_object_count_after_gc(is_alive_closure());
+}
+void PSParallelCompact::follow_class_loader(ParCompactionManager* cm,
+ClassLoaderData* cld) {
+PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
+PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure);
+cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true);
+}
+// This should be moved to the shared markSweep code!
+class PSAlwaysTrueClosure: public BoolObjectClosure {
+public:
+bool do_object_b(oop p) { return true; }
+};
+static PSAlwaysTrueClosure always_true;
+void PSParallelCompact::adjust_roots() {
+// Adjust the pointers to reflect the new locations
+GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer);
+// Need new claim bits when tracing through and adjusting pointers.
+ClassLoaderDataGraph::clear_claimed_marks();
+// General strong roots.
+Universe::oops_do(adjust_pointer_closure());
+JNIHandles::oops_do(adjust_pointer_closure());   // Global (strong) JNI handles
+CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
+Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
+ObjectSynchronizer::oops_do(adjust_pointer_closure());
+FlatProfiler::oops_do(adjust_pointer_closure());
+Management::oops_do(adjust_pointer_closure());
+JvmtiExport::oops_do(adjust_pointer_closure());
+// SO_AllClasses
+SystemDictionary::oops_do(adjust_pointer_closure());
+ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
+// 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_pointer_closure());
+CodeCache::oops_do(adjust_pointer_closure());
+StringTable::oops_do(adjust_pointer_closure());
+ref_processor()->weak_oops_do(adjust_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_pointer_closure());
+}
+void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
+uint parallel_gc_threads)
+{
+GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer);
+// Find the threads that are active
+unsigned int which = 0;
+const uint task_count = MAX2(parallel_gc_threads, 1U);
+for (uint j = 0; j < task_count; j++) {
+q->enqueue(new DrainStacksCompactionTask(j));
+ParCompactionManager::verify_region_list_empty(j);
+// Set the region stacks variables to "no" region stack values
+// so that they will be recognized and needing a region stack
+// in the stealing tasks if they do not get one by executing
+// a draining stack.
+ParCompactionManager* cm = ParCompactionManager::manager_array(j);
+cm->set_region_stack(NULL);
+cm->set_region_stack_index((uint)max_uintx);
+}
+ParCompactionManager::reset_recycled_stack_index();
+// Find all regions 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 regions will be removed in ascending order.
+const ParallelCompactData& sd = PSParallelCompact::summary_data();
+size_t fillable_regions = 0;   // A count for diagnostic purposes.
+// A region index which corresponds to the tasks created above.
+// "which" must be 0 <= which < task_count
+which = 0;
+// id + 1 is used to test termination so unsigned  can
+// be used with an old_space_id == 0.
+for (unsigned int id = to_space_id; id + 1 > old_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_region = sd.addr_to_region_idx(space_info->dense_prefix());
+const size_t end_region =
+sd.addr_to_region_idx(sd.region_align_up(new_top));
+for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
+if (sd.region(cur)->claim_unsafe()) {
+ParCompactionManager::region_list_push(which, cur);
+if (TraceParallelOldGCCompactionPhase && Verbose) {
+const size_t count_mod_8 = fillable_regions & 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_regions;)
+// Assign regions to tasks in round-robin fashion.
+if (++which == task_count) {
+assert(which <= parallel_gc_threads,
+"Inconsistent number of workers");
+which = 0;
+}
+}
+}
+}
+if (TraceParallelOldGCCompactionPhase) {
+if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
+gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
+}
+}
+#define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
+void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
+uint parallel_gc_threads) {
+GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer);
+ParallelCompactData& sd = PSParallelCompact::summary_data();
+// Iterate over all the spaces adding tasks for updating
+// regions 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.
+unsigned int space_id;
+for (space_id = old_space_id; space_id < last_space_id; ++ 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.
+continue;
+}
+// The dense prefix is before this region.
+size_t region_index_end_dense_prefix =
+sd.addr_to_region_idx(dense_prefix_end);
+RegionData* const dense_prefix_cp =
+sd.region(region_index_end_dense_prefix);
+assert(dense_prefix_end == space->end() ||
+dense_prefix_cp->available() ||
+dense_prefix_cp->claimed(),
+"The region after the dense prefix should always be ready to fill");
+size_t region_index_start = sd.addr_to_region_idx(space->bottom());
+// Is there dense prefix work?
+size_t total_dense_prefix_regions =
+region_index_end_dense_prefix - region_index_start;
+// How many regions of the dense prefix should be given to
+// each thread?
+if (total_dense_prefix_regions > 0) {
+uint tasks_for_dense_prefix = 1;
+if (total_dense_prefix_regions <=
+(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 regions 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 regions_per_thread = total_dense_prefix_regions /
+tasks_for_dense_prefix;
+// Give each thread at least 1 region.
+if (regions_per_thread == 0) {
+regions_per_thread = 1;
+}
+for (uint k = 0; k < tasks_for_dense_prefix; k++) {
+if (region_index_start >= region_index_end_dense_prefix) {
+break;
+}
+// region_index_end is not processed
+size_t region_index_end = MIN2(region_index_start + regions_per_thread,
+region_index_end_dense_prefix);
+q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
+region_index_start,
+region_index_end));
+region_index_start = region_index_end;
+}
+}
+// This gets any part of the dense prefix that did not
+// fit evenly.
+if (region_index_start < region_index_end_dense_prefix) {
+q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
+region_index_start,
+region_index_end_dense_prefix));
+}
+}
+}
+void PSParallelCompact::enqueue_region_stealing_tasks(
+GCTaskQueue* q,
+ParallelTaskTerminator* terminator_ptr,
+uint parallel_gc_threads) {
+GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer);
+// Once a thread has drained it's stack, it should try to steal regions from
+// other threads.
+if (parallel_gc_threads > 1) {
+for (uint j = 0; j < parallel_gc_threads; j++) {
+q->enqueue(new StealRegionCompactionTask(terminator_ptr));
+}
+}
+}
+#ifdef ASSERT
+// Write a histogram of the number of times the block table was filled for a
+// region.
+void PSParallelCompact::write_block_fill_histogram(outputStream* const out)
+{
+if (!TraceParallelOldGCCompactionPhase) return;
+typedef ParallelCompactData::RegionData rd_t;
+ParallelCompactData& sd = summary_data();
+for (unsigned int id = old_space_id; id < last_space_id; ++id) {
+MutableSpace* const spc = _space_info[id].space();
+if (spc->bottom() != spc->top()) {
+const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
+HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
+const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
+size_t histo[5] = { 0, 0, 0, 0, 0 };
+const size_t histo_len = sizeof(histo) / sizeof(size_t);
+const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
+for (const rd_t* cur = beg; cur < end; ++cur) {
+++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
+}
+out->print("%u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
+for (size_t i = 0; i < histo_len; ++i) {
+out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
+histo[i], 100.0 * histo[i] / region_cnt);
+}
+out->cr();
+}
+}
+}
+#endif // #ifdef ASSERT
+void PSParallelCompact::compact() {
+// trace("5");
+GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer);
+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();
+uint active_gc_threads = heap->gc_task_manager()->active_workers();
+TaskQueueSetSuper* qset = ParCompactionManager::region_array();
+ParallelTaskTerminator terminator(active_gc_threads, qset);
+GCTaskQueue* q = GCTaskQueue::create();
+enqueue_region_draining_tasks(q, active_gc_threads);
+enqueue_dense_prefix_tasks(q, active_gc_threads);
+enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
+{
+GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer);
+gc_task_manager()->execute_and_wait(q);
+#ifdef  ASSERT
+// Verify that all regions have been processed before the deferred updates.
+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.
+GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer);
+ParCompactionManager* cm = ParCompactionManager::manager_array(0);
+for (unsigned int id = old_space_id; id < last_space_id; ++id) {
+update_deferred_objects(cm, SpaceId(id));
+}
+}
+DEBUG_ONLY(write_block_fill_histogram(gclog_or_tty));
+}
+#ifdef  ASSERT
+void PSParallelCompact::verify_complete(SpaceId space_id) {
+// All Regions between space bottom() to new_top() should be marked as filled
+// and all Regions 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.region_align_up(si.new_top());
+HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
+const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
+const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
+const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
+bool issued_a_warning = false;
+size_t cur_region;
+for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
+const RegionData* const c = sd.region(cur_region);
+if (!c->completed()) {
+warning("region " SIZE_FORMAT " not filled:  "
+"destination_count=" SIZE_FORMAT,
+cur_region, c->destination_count());
+issued_a_warning = true;
+}
+}
+for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
+const RegionData* const c = sd.region(cur_region);
+if (!c->available()) {
+warning("region " SIZE_FORMAT " not empty:   "
+"destination_count=" SIZE_FORMAT,
+cur_region, c->destination_count());
+issued_a_warning = true;
+}
+}
+if (issued_a_warning) {
+print_region_ranges();
+}
+}
+#endif  // #ifdef ASSERT
+// Update interior oops in the ranges of regions [beg_region, end_region).
+void
+PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
+SpaceId space_id,
+size_t beg_region,
+size_t end_region) {
+ParallelCompactData& sd = summary_data();
+ParMarkBitMap* const mbm = mark_bitmap();
+HeapWord* beg_addr = sd.region_to_addr(beg_region);
+HeapWord* const end_addr = sd.region_to_addr(end_region);
+assert(beg_region <= end_region, "bad region range");
+assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
+#ifdef  ASSERT
+// Claim the regions to avoid triggering an assert when they are marked as
+// filled.
+for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
+assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
+}
+#endif  // #ifdef ASSERT
+if (beg_addr != space(space_id)->bottom()) {
+// Find the first live object or block of dead space that *starts* in this
+// range of regions.  If a partial object crosses onto the region, skip it;
+// it will be marked for 'deferred update' when the object head is
+// processed.  If dead space crosses onto the region, it is also skipped; it
+// will be filled when the prior region is processed.  If neither of those
+// apply, the first word in the region is the start of a live object or dead
+// space.
+assert(beg_addr > space(space_id)->bottom(), "sanity");
+const RegionData* const cp = sd.region(beg_region);
+if (cp->partial_obj_size() != 0) {
+beg_addr = sd.partial_obj_end(beg_region);
+} else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
+beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
+}
+}
+if (beg_addr < end_addr) {
+// A live object or block of dead space starts in this range of Regions.
+HeapWord* const dense_prefix_end = dense_prefix(space_id);
+// Create closures and iterate.
+UpdateOnlyClosure update_closure(mbm, cm, space_id);
+FillClosure fill_closure(cm, space_id);
+ParMarkBitMap::IterationStatus status;
+status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
+dense_prefix_end);
+if (status == ParMarkBitMap::incomplete) {
+update_closure.do_addr(update_closure.source());
+}
+}
+// Mark the regions as filled.
+RegionData* const beg_cp = sd.region(beg_region);
+RegionData* const end_cp = sd.region(end_region);
+for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
+cp->set_completed();
+}
+}
+// Return the SpaceId for the space containing addr.  If addr is not in the
+// heap, last_space_id is returned.  In debug mode it expects the address to be
+// in the heap and asserts such.
+PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
+assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
+for (unsigned int id = old_space_id; id < last_space_id; ++id) {
+if (_space_info[id].space()->contains(addr)) {
+return SpaceId(id);
+}
+}
+assert(false, "no space contains the addr");
+return last_space_id;
+}
+void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
+SpaceId id) {
+assert(id < last_space_id, "bad space id");
+ParallelCompactData& sd = summary_data();
+const SpaceInfo* const space_info = _space_info + id;
+ObjectStartArray* const start_array = space_info->start_array();
+const MutableSpace* const space = space_info->space();
+assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
+HeapWord* const beg_addr = space_info->dense_prefix();
+HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
+const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
+const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
+const RegionData* cur_region;
+for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
+HeapWord* const addr = cur_region->deferred_obj_addr();
+if (addr != NULL) {
+if (start_array != NULL) {
+start_array->allocate_block(addr);
+}
+oop(addr)->update_contents(cm);
+assert(oop(addr)->is_oop_or_null(), "should be an oop now");
+}
+}
+}
+// Skip over count live words starting from beg, and return the address of the
+// next live word.  Unless marked, the word corresponding to beg is assumed to
+// be dead.  Callers must either ensure beg does not correspond to the middle of
+// an object, or account for those live words in some other way.  Callers must
+// also ensure that there are enough live words in the range [beg, end) to skip.
+HeapWord*
+PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
+{
+assert(count > 0, "sanity");
+ParMarkBitMap* m = mark_bitmap();
+idx_t bits_to_skip = m->words_to_bits(count);
+idx_t cur_beg = m->addr_to_bit(beg);
+const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
+do {
+cur_beg = m->find_obj_beg(cur_beg, search_end);
+idx_t cur_end = m->find_obj_end(cur_beg, search_end);
+const size_t obj_bits = cur_end - cur_beg + 1;
+if (obj_bits > bits_to_skip) {
+return m->bit_to_addr(cur_beg + bits_to_skip);
+}
+bits_to_skip -= obj_bits;
+cur_beg = cur_end + 1;
+} while (bits_to_skip > 0);
+// Skipping the desired number of words landed just past the end of an object.
+// Find the start of the next object.
+cur_beg = m->find_obj_beg(cur_beg, search_end);
+assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
+return m->bit_to_addr(cur_beg);
+}
+HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
+SpaceId src_space_id,
+size_t src_region_idx)
+{
+assert(summary_data().is_region_aligned(dest_addr), "not aligned");
+const SplitInfo& split_info = _space_info[src_space_id].split_info();
+if (split_info.dest_region_addr() == dest_addr) {
+// The partial object ending at the split point contains the first word to
+// be copied to dest_addr.
+return split_info.first_src_addr();
+}
+const ParallelCompactData& sd = summary_data();
+ParMarkBitMap* const bitmap = mark_bitmap();
+const size_t RegionSize = ParallelCompactData::RegionSize;
+assert(sd.is_region_aligned(dest_addr), "not aligned");
+const RegionData* const src_region_ptr = sd.region(src_region_idx);
+const size_t partial_obj_size = src_region_ptr->partial_obj_size();
+HeapWord* const src_region_destination = src_region_ptr->destination();
+assert(dest_addr >= src_region_destination, "wrong src region");
+assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
+HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
+HeapWord* const src_region_end = src_region_beg + RegionSize;
+HeapWord* addr = src_region_beg;
+if (dest_addr == src_region_destination) {
+// Return the first live word in the source region.
+if (partial_obj_size == 0) {
+addr = bitmap->find_obj_beg(addr, src_region_end);
+assert(addr < src_region_end, "no objects start in src region");
+}
+return addr;
+}
+// Must skip some live data.
+size_t words_to_skip = dest_addr - src_region_destination;
+assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
+if (partial_obj_size >= words_to_skip) {
+// All the live words to skip are part of the partial object.
+addr += words_to_skip;
+if (partial_obj_size == words_to_skip) {
+// Find the first live word past the partial object.
+addr = bitmap->find_obj_beg(addr, src_region_end);
+assert(addr < src_region_end, "wrong src region");
+}
+return addr;
+}
+// Skip over the partial object (if any).
+if (partial_obj_size != 0) {
+words_to_skip -= partial_obj_size;
+addr += partial_obj_size;
+}
+// Skip over live words due to objects that start in the region.
+addr = skip_live_words(addr, src_region_end, words_to_skip);
+assert(addr < src_region_end, "wrong src region");
+return addr;
+}
+void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
+SpaceId src_space_id,
+size_t beg_region,
+HeapWord* end_addr)
+{
+ParallelCompactData& sd = summary_data();
+#ifdef ASSERT
+MutableSpace* const src_space = _space_info[src_space_id].space();
+HeapWord* const beg_addr = sd.region_to_addr(beg_region);
+assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
+"src_space_id does not match beg_addr");
+assert(src_space->contains(end_addr) || end_addr == src_space->end(),
+"src_space_id does not match end_addr");
+#endif // #ifdef ASSERT
+RegionData* const beg = sd.region(beg_region);
+RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
+// Regions up to new_top() are enqueued if they become available.
+HeapWord* const new_top = _space_info[src_space_id].new_top();
+RegionData* const enqueue_end =
+sd.addr_to_region_ptr(sd.region_align_up(new_top));
+for (RegionData* cur = beg; cur < end; ++cur) {
+assert(cur->data_size() > 0, "region must have live data");
+cur->decrement_destination_count();
+if (cur < enqueue_end && cur->available() && cur->claim()) {
+cm->push_region(sd.region(cur));
+}
+}
+}
+size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
+SpaceId& src_space_id,
+HeapWord*& src_space_top,
+HeapWord* end_addr)
+{
+typedef ParallelCompactData::RegionData RegionData;
+ParallelCompactData& sd = PSParallelCompact::summary_data();
+const size_t region_size = ParallelCompactData::RegionSize;
+size_t src_region_idx = 0;
+// Skip empty regions (if any) up to the top of the space.
+HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
+RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
+HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
+const RegionData* const top_region_ptr =
+sd.addr_to_region_ptr(top_aligned_up);
+while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
+++src_region_ptr;
+}
+if (src_region_ptr < top_region_ptr) {
+// The next source region is in the current space.  Update src_region_idx
+// and the source address to match src_region_ptr.
+src_region_idx = sd.region(src_region_ptr);
+HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
+if (src_region_addr > closure.source()) {
+closure.set_source(src_region_addr);
+}
+return src_region_idx;
+}
+// Switch to a new source space and find the first non-empty region.
+unsigned int space_id = src_space_id + 1;
+assert(space_id < last_space_id, "not enough spaces");
+HeapWord* const destination = closure.destination();
+do {
+MutableSpace* space = _space_info[space_id].space();
+HeapWord* const bottom = space->bottom();
+const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
+// Iterate over the spaces that do not compact into themselves.
+if (bottom_cp->destination() != bottom) {
+HeapWord* const top_aligned_up = sd.region_align_up(space->top());
+const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
+for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
+if (src_cp->live_obj_size() > 0) {
+// Found it.
+assert(src_cp->destination() == destination,
+"first live obj in the space must match the destination");
+assert(src_cp->partial_obj_size() == 0,
+"a space cannot begin with a partial obj");
+src_space_id = SpaceId(space_id);
+src_space_top = space->top();
+const size_t src_region_idx = sd.region(src_cp);
+closure.set_source(sd.region_to_addr(src_region_idx));
+return src_region_idx;
+} else {
+assert(src_cp->data_size() == 0, "sanity");
+}
+}
+}
+} while (++space_id < last_space_id);
+assert(false, "no source region was found");
+return 0;
+}
+void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
+{
+typedef ParMarkBitMap::IterationStatus IterationStatus;
+const size_t RegionSize = ParallelCompactData::RegionSize;
+ParMarkBitMap* const bitmap = mark_bitmap();
+ParallelCompactData& sd = summary_data();
+RegionData* const region_ptr = sd.region(region_idx);
+// Get the items needed to construct the closure.
+HeapWord* dest_addr = sd.region_to_addr(region_idx);
+SpaceId dest_space_id = space_id(dest_addr);
+ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
+HeapWord* new_top = _space_info[dest_space_id].new_top();
+assert(dest_addr < new_top, "sanity");
+const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
+// Get the source region and related info.
+size_t src_region_idx = region_ptr->source_region();
+SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
+HeapWord* src_space_top = _space_info[src_space_id].space()->top();
+MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
+closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
+// Adjust src_region_idx to prepare for decrementing destination counts (the
+// destination count is not decremented when a region is copied to itself).
+if (src_region_idx == region_idx) {
+src_region_idx += 1;
+}
+if (bitmap->is_unmarked(closure.source())) {
+// The first source word is in the middle of an object; copy the remainder
+// of the object or as much as will fit.  The fact that pointer updates were
+// deferred will be noted when the object header is processed.
+HeapWord* const old_src_addr = closure.source();
+closure.copy_partial_obj();
+if (closure.is_full()) {
+decrement_destination_counts(cm, src_space_id, src_region_idx,
+closure.source());
+region_ptr->set_deferred_obj_addr(NULL);
+region_ptr->set_completed();
+return;
+}
+HeapWord* const end_addr = sd.region_align_down(closure.source());
+if (sd.region_align_down(old_src_addr) != end_addr) {
+// The partial object was copied from more than one source region.
+decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
+// Move to the next source region, possibly switching spaces as well.  All
+// args except end_addr may be modified.
+src_region_idx = next_src_region(closure, src_space_id, src_space_top,
+end_addr);
+}
+}
+do {
+HeapWord* const cur_addr = closure.source();
+HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
+src_space_top);
+IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
+if (status == ParMarkBitMap::incomplete) {
+// The last obj that starts in the source region does not end in the
+// region.
+assert(closure.source() < end_addr, "sanity");
+HeapWord* const obj_beg = closure.source();
+HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
+src_space_top);
+HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
+if (obj_end < range_end) {
+// The end was found; the entire object will fit.
+status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
+assert(status != ParMarkBitMap::would_overflow, "sanity");
+} else {
+// The end was not found; the object will not fit.
+assert(range_end < src_space_top, "obj cannot cross space boundary");
+status = ParMarkBitMap::would_overflow;
+}
+}
+if (status == ParMarkBitMap::would_overflow) {
+// The last object did not fit.  Note that interior oop updates were
+// deferred, then copy enough of the object to fill the region.
+region_ptr->set_deferred_obj_addr(closure.destination());
+status = closure.copy_until_full(); // copies from closure.source()
+decrement_destination_counts(cm, src_space_id, src_region_idx,
+closure.source());
+region_ptr->set_completed();
+return;
+}
+if (status == ParMarkBitMap::full) {
+decrement_destination_counts(cm, src_space_id, src_region_idx,
+closure.source());
+region_ptr->set_deferred_obj_addr(NULL);
+region_ptr->set_completed();
+return;
+}
+decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
+// Move to the next source region, possibly switching spaces as well.  All
+// args except end_addr may be modified.
+src_region_idx = next_src_region(closure, src_space_id, src_space_top,
+end_addr);
+} while (true);
+}
+void PSParallelCompact::fill_blocks(size_t region_idx)
+{
+// Fill in the block table elements for the specified region.  Each block
+// table element holds the number of live words in the region that are to the
+// left of the first object that starts in the block.  Thus only blocks in
+// which an object starts need to be filled.
+//
+// The algorithm scans the section of the bitmap that corresponds to the
+// region, keeping a running total of the live words.  When an object start is
+// found, if it's the first to start in the block that contains it, the
+// current total is written to the block table element.
+const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
+const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
+const size_t RegionSize = ParallelCompactData::RegionSize;
+ParallelCompactData& sd = summary_data();
+const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
+if (partial_obj_size >= RegionSize) {
+return; // No objects start in this region.
+}
+// Ensure the first loop iteration decides that the block has changed.
+size_t cur_block = sd.block_count();
+const ParMarkBitMap* const bitmap = mark_bitmap();
+const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
+assert((size_t)1 << Log2BitsPerBlock ==
+bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
+size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
+const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
+size_t live_bits = bitmap->words_to_bits(partial_obj_size);
+beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
+while (beg_bit < range_end) {
+const size_t new_block = beg_bit >> Log2BitsPerBlock;
+if (new_block != cur_block) {
+cur_block = new_block;
+sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
+}
+const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
+if (end_bit < range_end - 1) {
+live_bits += end_bit - beg_bit + 1;
+beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
+} else {
+return;
+}
+}
+}
+void
+PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
+const MutableSpace* sp = space(space_id);
+if (sp->is_empty()) {
+return;
+}
+ParallelCompactData& sd = PSParallelCompact::summary_data();
+ParMarkBitMap* const bitmap = mark_bitmap();
+HeapWord* const dp_addr = dense_prefix(space_id);
+HeapWord* beg_addr = sp->bottom();
+HeapWord* end_addr = sp->top();
+assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
+const size_t beg_region = sd.addr_to_region_idx(beg_addr);
+const size_t dp_region = sd.addr_to_region_idx(dp_addr);
+if (beg_region < dp_region) {
+update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
+}
+// The destination of the first live object that starts in the region is one
+// past the end of the partial object entering the region (if any).
+HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
+HeapWord* const new_top = _space_info[space_id].new_top();
+assert(new_top >= dest_addr, "bad new_top value");
+const size_t words = pointer_delta(new_top, dest_addr);
+if (words > 0) {
+ObjectStartArray* start_array = _space_info[space_id].start_array();
+MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
+ParMarkBitMap::IterationStatus status;
+status = bitmap->iterate(&closure, dest_addr, end_addr);
+assert(status == ParMarkBitMap::full, "iteration not complete");
+assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
+"live objects skipped because closure is full");
+}
+}
+jlong PSParallelCompact::millis_since_last_gc() {
+// We need a monotonically non-deccreasing time in ms but
+// os::javaTimeMillis() does not guarantee monotonicity.
+jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+jlong ret_val = now - _time_of_last_gc;
+// XXX See note in genCollectedHeap::millis_since_last_gc().
+if (ret_val < 0) {
+NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
+return 0;
+}
+return ret_val;
+}
+void PSParallelCompact::reset_millis_since_last_gc() {
+// We need a monotonically non-deccreasing time in ms but
+// os::javaTimeMillis() does not guarantee monotonicity.
+_time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
+}
+ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
+{
+if (source() != destination()) {
+DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
+Copy::aligned_conjoint_words(source(), destination(), words_remaining());
+}
+update_state(words_remaining());
+assert(is_full(), "sanity");
+return ParMarkBitMap::full;
+}
+void MoveAndUpdateClosure::copy_partial_obj()
+{
+size_t words = words_remaining();
+HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
+HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
+if (end_addr < range_end) {
+words = bitmap()->obj_size(source(), end_addr);
+}
+// This test is necessary; if omitted, the pointer updates to a partial object
+// that crosses the dense prefix boundary could be overwritten.
+if (source() != destination()) {
+DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
+Copy::aligned_conjoint_words(source(), destination(), words);
+}
+update_state(words);
+}
+ParMarkBitMapClosure::IterationStatus
+MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
+assert(destination() != NULL, "sanity");
+assert(bitmap()->obj_size(addr) == words, "bad size");
+_source = addr;
+assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
+destination(), "wrong destination");
+if (words > words_remaining()) {
+return ParMarkBitMap::would_overflow;
+}
+// The start_array must be updated even if the object is not moving.
+if (_start_array != NULL) {
+_start_array->allocate_block(destination());
+}
+if (destination() != source()) {
+DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
+Copy::aligned_conjoint_words(source(), destination(), words);
+}
+oop moved_oop = (oop) destination();
+moved_oop->update_contents(compaction_manager());
+assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
+update_state(words);
+assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
+return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
+}
+UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
+ParCompactionManager* cm,
+PSParallelCompact::SpaceId space_id) :
+ParMarkBitMapClosure(mbm, cm),
+_space_id(space_id),
+_start_array(PSParallelCompact::start_array(space_id))
+{
+}
+// Updates the references in the object to their new values.
+ParMarkBitMapClosure::IterationStatus
+UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
+do_addr(addr);
+return ParMarkBitMap::incomplete;
+}

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

comparison: src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp