diff -r 000000000000 -r f90c822e73f8 src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp Wed Apr 27 01:25:04 2016 +0800 @@ -0,0 +1,3383 @@ +/* + * 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 + +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; +}