Mercurial > hg > truffle
view src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp @ 266:2214b226b7f0
6724367: par compact could clear less young gen summary data
Reviewed-by: jmasa, apetrusenko
author | jcoomes |
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date | Fri, 11 Jul 2008 16:11:50 -0700 |
parents | f88815ca1af1 |
children | 850fdf70db2b |
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/* * Copyright 2005-2007 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ #include "incls/_precompiled.incl" #include "incls/_psParallelCompact.cpp.incl" #include <math.h> // All sizes are in HeapWords. const size_t ParallelCompactData::Log2ChunkSize = 9; // 512 words const size_t ParallelCompactData::ChunkSize = (size_t)1 << Log2ChunkSize; const size_t ParallelCompactData::ChunkSizeBytes = ChunkSize << LogHeapWordSize; const size_t ParallelCompactData::ChunkSizeOffsetMask = ChunkSize - 1; const size_t ParallelCompactData::ChunkAddrOffsetMask = ChunkSizeBytes - 1; const size_t ParallelCompactData::ChunkAddrMask = ~ChunkAddrOffsetMask; // 32-bit: 128 words covers 4 bitmap words // 64-bit: 128 words covers 2 bitmap words const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize; const size_t ParallelCompactData::BlockOffsetMask = BlockSize - 1; const size_t ParallelCompactData::BlockMask = ~BlockOffsetMask; const size_t ParallelCompactData::BlocksPerChunk = ChunkSize / BlockSize; const ParallelCompactData::ChunkData::chunk_sz_t ParallelCompactData::ChunkData::dc_shift = 27; const ParallelCompactData::ChunkData::chunk_sz_t ParallelCompactData::ChunkData::dc_mask = ~0U << dc_shift; const ParallelCompactData::ChunkData::chunk_sz_t ParallelCompactData::ChunkData::dc_one = 0x1U << dc_shift; const ParallelCompactData::ChunkData::chunk_sz_t ParallelCompactData::ChunkData::los_mask = ~dc_mask; const ParallelCompactData::ChunkData::chunk_sz_t ParallelCompactData::ChunkData::dc_claimed = 0x8U << dc_shift; const ParallelCompactData::ChunkData::chunk_sz_t ParallelCompactData::ChunkData::dc_completed = 0xcU << dc_shift; #ifdef ASSERT short ParallelCompactData::BlockData::_cur_phase = 0; #endif SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id]; bool PSParallelCompact::_print_phases = false; ReferenceProcessor* PSParallelCompact::_ref_processor = NULL; klassOop PSParallelCompact::_updated_int_array_klass_obj = NULL; double PSParallelCompact::_dwl_mean; double PSParallelCompact::_dwl_std_dev; double PSParallelCompact::_dwl_first_term; double PSParallelCompact::_dwl_adjustment; #ifdef ASSERT bool PSParallelCompact::_dwl_initialized = false; #endif // #ifdef ASSERT #ifdef VALIDATE_MARK_SWEEP GrowableArray<void*>* PSParallelCompact::_root_refs_stack = NULL; GrowableArray<oop> * PSParallelCompact::_live_oops = NULL; GrowableArray<oop> * PSParallelCompact::_live_oops_moved_to = NULL; GrowableArray<size_t>* PSParallelCompact::_live_oops_size = NULL; size_t PSParallelCompact::_live_oops_index = 0; size_t PSParallelCompact::_live_oops_index_at_perm = 0; GrowableArray<void*>* PSParallelCompact::_other_refs_stack = NULL; GrowableArray<void*>* PSParallelCompact::_adjusted_pointers = NULL; bool PSParallelCompact::_pointer_tracking = false; bool PSParallelCompact::_root_tracking = true; GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL; GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL; GrowableArray<size_t> * PSParallelCompact::_cur_gc_live_oops_size = NULL; GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL; GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL; GrowableArray<size_t> * PSParallelCompact::_last_gc_live_oops_size = NULL; #endif // XXX beg - verification code; only works while we also mark in object headers static void verify_mark_bitmap(ParMarkBitMap& _mark_bitmap) { ParallelScavengeHeap* heap = PSParallelCompact::gc_heap(); PSPermGen* perm_gen = heap->perm_gen(); PSOldGen* old_gen = heap->old_gen(); PSYoungGen* young_gen = heap->young_gen(); MutableSpace* perm_space = perm_gen->object_space(); MutableSpace* old_space = old_gen->object_space(); MutableSpace* eden_space = young_gen->eden_space(); MutableSpace* from_space = young_gen->from_space(); MutableSpace* to_space = young_gen->to_space(); // 'from_space' here is the survivor space at the lower address. if (to_space->bottom() < from_space->bottom()) { from_space = to_space; to_space = young_gen->from_space(); } HeapWord* boundaries[12]; unsigned int bidx = 0; const unsigned int bidx_max = sizeof(boundaries) / sizeof(boundaries[0]); boundaries[0] = perm_space->bottom(); boundaries[1] = perm_space->top(); boundaries[2] = old_space->bottom(); boundaries[3] = old_space->top(); boundaries[4] = eden_space->bottom(); boundaries[5] = eden_space->top(); boundaries[6] = from_space->bottom(); boundaries[7] = from_space->top(); boundaries[8] = to_space->bottom(); boundaries[9] = to_space->top(); boundaries[10] = to_space->end(); boundaries[11] = to_space->end(); BitMap::idx_t beg_bit = 0; BitMap::idx_t end_bit; BitMap::idx_t tmp_bit; const BitMap::idx_t last_bit = _mark_bitmap.size(); do { HeapWord* addr = _mark_bitmap.bit_to_addr(beg_bit); if (_mark_bitmap.is_marked(beg_bit)) { oop obj = (oop)addr; assert(obj->is_gc_marked(), "obj header is not marked"); end_bit = _mark_bitmap.find_obj_end(beg_bit, last_bit); const size_t size = _mark_bitmap.obj_size(beg_bit, end_bit); assert(size == (size_t)obj->size(), "end bit wrong?"); beg_bit = _mark_bitmap.find_obj_beg(beg_bit + 1, last_bit); assert(beg_bit > end_bit, "bit set in middle of an obj"); } else { if (addr >= boundaries[bidx] && addr < boundaries[bidx + 1]) { // a dead object in the current space. oop obj = (oop)addr; end_bit = _mark_bitmap.addr_to_bit(addr + obj->size()); assert(!obj->is_gc_marked(), "obj marked in header, not in bitmap"); tmp_bit = beg_bit + 1; beg_bit = _mark_bitmap.find_obj_beg(tmp_bit, end_bit); assert(beg_bit == end_bit, "beg bit set in unmarked obj"); beg_bit = _mark_bitmap.find_obj_end(tmp_bit, end_bit); assert(beg_bit == end_bit, "end bit set in unmarked obj"); } else if (addr < boundaries[bidx + 2]) { // addr is between top in the current space and bottom in the next. end_bit = beg_bit + pointer_delta(boundaries[bidx + 2], addr); tmp_bit = beg_bit; beg_bit = _mark_bitmap.find_obj_beg(tmp_bit, end_bit); assert(beg_bit == end_bit, "beg bit set above top"); beg_bit = _mark_bitmap.find_obj_end(tmp_bit, end_bit); assert(beg_bit == end_bit, "end bit set above top"); bidx += 2; } else if (bidx < bidx_max - 2) { bidx += 2; // ??? } else { tmp_bit = beg_bit; beg_bit = _mark_bitmap.find_obj_beg(tmp_bit, last_bit); assert(beg_bit == last_bit, "beg bit set outside heap"); beg_bit = _mark_bitmap.find_obj_end(tmp_bit, last_bit); assert(beg_bit == last_bit, "end bit set outside heap"); } } } while (beg_bit < last_bit); } // XXX end - verification code; only works while we also mark in object headers #ifndef PRODUCT const char* PSParallelCompact::space_names[] = { "perm", "old ", "eden", "from", "to " }; void PSParallelCompact::print_chunk_ranges() { tty->print_cr("space bottom top end new_top"); tty->print_cr("------ ---------- ---------- ---------- ----------"); for (unsigned int id = 0; id < last_space_id; ++id) { const MutableSpace* space = _space_info[id].space(); tty->print_cr("%u %s " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ", id, space_names[id], summary_data().addr_to_chunk_idx(space->bottom()), summary_data().addr_to_chunk_idx(space->top()), summary_data().addr_to_chunk_idx(space->end()), summary_data().addr_to_chunk_idx(_space_info[id].new_top())); } } void print_generic_summary_chunk(size_t i, const ParallelCompactData::ChunkData* c) { #define CHUNK_IDX_FORMAT SIZE_FORMAT_W(7) #define CHUNK_DATA_FORMAT SIZE_FORMAT_W(5) ParallelCompactData& sd = PSParallelCompact::summary_data(); size_t dci = c->destination() ? sd.addr_to_chunk_idx(c->destination()) : 0; tty->print_cr(CHUNK_IDX_FORMAT " " PTR_FORMAT " " CHUNK_IDX_FORMAT " " PTR_FORMAT " " CHUNK_DATA_FORMAT " " CHUNK_DATA_FORMAT " " CHUNK_DATA_FORMAT " " CHUNK_IDX_FORMAT " %d", i, c->data_location(), dci, c->destination(), c->partial_obj_size(), c->live_obj_size(), c->data_size(), c->source_chunk(), c->destination_count()); #undef CHUNK_IDX_FORMAT #undef CHUNK_DATA_FORMAT } void print_generic_summary_data(ParallelCompactData& summary_data, HeapWord* const beg_addr, HeapWord* const end_addr) { size_t total_words = 0; size_t i = summary_data.addr_to_chunk_idx(beg_addr); const size_t last = summary_data.addr_to_chunk_idx(end_addr); HeapWord* pdest = 0; while (i <= last) { ParallelCompactData::ChunkData* c = summary_data.chunk(i); if (c->data_size() != 0 || c->destination() != pdest) { print_generic_summary_chunk(i, c); total_words += c->data_size(); pdest = c->destination(); } ++i; } tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize); } void print_generic_summary_data(ParallelCompactData& summary_data, SpaceInfo* space_info) { for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) { const MutableSpace* space = space_info[id].space(); print_generic_summary_data(summary_data, space->bottom(), MAX2(space->top(), space_info[id].new_top())); } } void print_initial_summary_chunk(size_t i, const ParallelCompactData::ChunkData* c, bool newline = true) { tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d", i, c->destination(), c->partial_obj_size(), c->live_obj_size(), c->data_size(), c->source_chunk(), c->destination_count()); if (newline) tty->cr(); } void print_initial_summary_data(ParallelCompactData& summary_data, const MutableSpace* space) { if (space->top() == space->bottom()) { return; } const size_t chunk_size = ParallelCompactData::ChunkSize; HeapWord* const top_aligned_up = summary_data.chunk_align_up(space->top()); const size_t end_chunk = summary_data.addr_to_chunk_idx(top_aligned_up); const ParallelCompactData::ChunkData* c = summary_data.chunk(end_chunk - 1); HeapWord* end_addr = c->destination() + c->data_size(); const size_t live_in_space = pointer_delta(end_addr, space->bottom()); // Print (and count) the full chunks at the beginning of the space. size_t full_chunk_count = 0; size_t i = summary_data.addr_to_chunk_idx(space->bottom()); while (i < end_chunk && summary_data.chunk(i)->data_size() == chunk_size) { print_initial_summary_chunk(i, summary_data.chunk(i)); ++full_chunk_count; ++i; } size_t live_to_right = live_in_space - full_chunk_count * chunk_size; double max_reclaimed_ratio = 0.0; size_t max_reclaimed_ratio_chunk = 0; size_t max_dead_to_right = 0; size_t max_live_to_right = 0; // Print the 'reclaimed ratio' for chunks while there is something live in the // chunk or to the right of it. The remaining chunks are empty (and // uninteresting), and computing the ratio will result in division by 0. while (i < end_chunk && live_to_right > 0) { c = summary_data.chunk(i); HeapWord* const chunk_addr = summary_data.chunk_to_addr(i); const size_t used_to_right = pointer_delta(space->top(), chunk_addr); const size_t dead_to_right = used_to_right - live_to_right; const double reclaimed_ratio = double(dead_to_right) / live_to_right; if (reclaimed_ratio > max_reclaimed_ratio) { max_reclaimed_ratio = reclaimed_ratio; max_reclaimed_ratio_chunk = i; max_dead_to_right = dead_to_right; max_live_to_right = live_to_right; } print_initial_summary_chunk(i, c, false); tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10), reclaimed_ratio, dead_to_right, live_to_right); live_to_right -= c->data_size(); ++i; } // Any remaining chunks are empty. Print one more if there is one. if (i < end_chunk) { print_initial_summary_chunk(i, summary_data.chunk(i)); } tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " " "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f", max_reclaimed_ratio_chunk, max_dead_to_right, max_live_to_right, max_reclaimed_ratio); } void print_initial_summary_data(ParallelCompactData& summary_data, SpaceInfo* space_info) { unsigned int id = PSParallelCompact::perm_space_id; const MutableSpace* space; do { space = space_info[id].space(); print_initial_summary_data(summary_data, space); } while (++id < PSParallelCompact::eden_space_id); do { space = space_info[id].space(); print_generic_summary_data(summary_data, space->bottom(), space->top()); } while (++id < PSParallelCompact::last_space_id); } #endif // #ifndef PRODUCT #ifdef ASSERT size_t add_obj_count; size_t add_obj_size; size_t mark_bitmap_count; size_t mark_bitmap_size; #endif // #ifdef ASSERT ParallelCompactData::ParallelCompactData() { _region_start = 0; _chunk_vspace = 0; _chunk_data = 0; _chunk_count = 0; _block_vspace = 0; _block_data = 0; _block_count = 0; } bool ParallelCompactData::initialize(MemRegion covered_region) { _region_start = covered_region.start(); const size_t region_size = covered_region.word_size(); DEBUG_ONLY(_region_end = _region_start + region_size;) assert(chunk_align_down(_region_start) == _region_start, "region start not aligned"); assert((region_size & ChunkSizeOffsetMask) == 0, "region size not a multiple of ChunkSize"); bool result = initialize_chunk_data(region_size); // Initialize the block data if it will be used for updating pointers, or if // this is a debug build. if (!UseParallelOldGCChunkPointerCalc || trueInDebug) { result = result && initialize_block_data(region_size); } return result; } PSVirtualSpace* ParallelCompactData::create_vspace(size_t count, size_t element_size) { const size_t raw_bytes = count * element_size; const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10); const size_t granularity = os::vm_allocation_granularity(); const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity)); const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 : MAX2(page_sz, granularity); ReservedSpace rs(bytes, rs_align, rs_align > 0); os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(), rs.size()); PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz); if (vspace != 0) { if (vspace->expand_by(bytes)) { return vspace; } delete vspace; } return 0; } bool ParallelCompactData::initialize_chunk_data(size_t region_size) { const size_t count = (region_size + ChunkSizeOffsetMask) >> Log2ChunkSize; _chunk_vspace = create_vspace(count, sizeof(ChunkData)); if (_chunk_vspace != 0) { _chunk_data = (ChunkData*)_chunk_vspace->reserved_low_addr(); _chunk_count = count; return true; } return false; } bool ParallelCompactData::initialize_block_data(size_t region_size) { const size_t count = (region_size + BlockOffsetMask) >> Log2BlockSize; _block_vspace = create_vspace(count, sizeof(BlockData)); if (_block_vspace != 0) { _block_data = (BlockData*)_block_vspace->reserved_low_addr(); _block_count = count; return true; } return false; } void ParallelCompactData::clear() { if (_block_data) { memset(_block_data, 0, _block_vspace->committed_size()); } memset(_chunk_data, 0, _chunk_vspace->committed_size()); } void ParallelCompactData::clear_range(size_t beg_chunk, size_t end_chunk) { assert(beg_chunk <= _chunk_count, "beg_chunk out of range"); assert(end_chunk <= _chunk_count, "end_chunk out of range"); assert(ChunkSize % BlockSize == 0, "ChunkSize not a multiple of BlockSize"); const size_t chunk_cnt = end_chunk - beg_chunk; if (_block_data) { const size_t blocks_per_chunk = ChunkSize / BlockSize; const size_t beg_block = beg_chunk * blocks_per_chunk; const size_t block_cnt = chunk_cnt * blocks_per_chunk; memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData)); } memset(_chunk_data + beg_chunk, 0, chunk_cnt * sizeof(ChunkData)); } HeapWord* ParallelCompactData::partial_obj_end(size_t chunk_idx) const { const ChunkData* cur_cp = chunk(chunk_idx); const ChunkData* const end_cp = chunk(chunk_count() - 1); HeapWord* result = chunk_to_addr(chunk_idx); if (cur_cp < end_cp) { do { result += cur_cp->partial_obj_size(); } while (cur_cp->partial_obj_size() == ChunkSize && ++cur_cp < end_cp); } return result; } void ParallelCompactData::add_obj(HeapWord* addr, size_t len) { const size_t obj_ofs = pointer_delta(addr, _region_start); const size_t beg_chunk = obj_ofs >> Log2ChunkSize; const size_t end_chunk = (obj_ofs + len - 1) >> Log2ChunkSize; DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);) DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);) if (beg_chunk == end_chunk) { // All in one chunk. _chunk_data[beg_chunk].add_live_obj(len); return; } // First chunk. const size_t beg_ofs = chunk_offset(addr); _chunk_data[beg_chunk].add_live_obj(ChunkSize - beg_ofs); klassOop klass = ((oop)addr)->klass(); // Middle chunks--completely spanned by this object. for (size_t chunk = beg_chunk + 1; chunk < end_chunk; ++chunk) { _chunk_data[chunk].set_partial_obj_size(ChunkSize); _chunk_data[chunk].set_partial_obj_addr(addr); } // Last chunk. const size_t end_ofs = chunk_offset(addr + len - 1); _chunk_data[end_chunk].set_partial_obj_size(end_ofs + 1); _chunk_data[end_chunk].set_partial_obj_addr(addr); } void ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end) { assert(chunk_offset(beg) == 0, "not ChunkSize aligned"); assert(chunk_offset(end) == 0, "not ChunkSize aligned"); size_t cur_chunk = addr_to_chunk_idx(beg); const size_t end_chunk = addr_to_chunk_idx(end); HeapWord* addr = beg; while (cur_chunk < end_chunk) { _chunk_data[cur_chunk].set_destination(addr); _chunk_data[cur_chunk].set_destination_count(0); _chunk_data[cur_chunk].set_source_chunk(cur_chunk); _chunk_data[cur_chunk].set_data_location(addr); // Update live_obj_size so the chunk appears completely full. size_t live_size = ChunkSize - _chunk_data[cur_chunk].partial_obj_size(); _chunk_data[cur_chunk].set_live_obj_size(live_size); ++cur_chunk; addr += ChunkSize; } } bool ParallelCompactData::summarize(HeapWord* target_beg, HeapWord* target_end, HeapWord* source_beg, HeapWord* source_end, HeapWord** target_next, HeapWord** source_next) { // This is too strict. // assert(chunk_offset(source_beg) == 0, "not ChunkSize aligned"); if (TraceParallelOldGCSummaryPhase) { tty->print_cr("tb=" PTR_FORMAT " te=" PTR_FORMAT " " "sb=" PTR_FORMAT " se=" PTR_FORMAT " " "tn=" PTR_FORMAT " sn=" PTR_FORMAT, target_beg, target_end, source_beg, source_end, target_next != 0 ? *target_next : (HeapWord*) 0, source_next != 0 ? *source_next : (HeapWord*) 0); } size_t cur_chunk = addr_to_chunk_idx(source_beg); const size_t end_chunk = addr_to_chunk_idx(chunk_align_up(source_end)); HeapWord *dest_addr = target_beg; while (cur_chunk < end_chunk) { size_t words = _chunk_data[cur_chunk].data_size(); #if 1 assert(pointer_delta(target_end, dest_addr) >= words, "source region does not fit into target region"); #else // XXX - need some work on the corner cases here. If the chunk does not // fit, then must either make sure any partial_obj from the chunk fits, or // 'undo' the initial part of the partial_obj that is in the previous chunk. if (dest_addr + words >= target_end) { // Let the caller know where to continue. *target_next = dest_addr; *source_next = chunk_to_addr(cur_chunk); return false; } #endif // #if 1 _chunk_data[cur_chunk].set_destination(dest_addr); // Set the destination_count for cur_chunk, and if necessary, update // source_chunk for a destination chunk. The source_chunk field is updated // if cur_chunk is the first (left-most) chunk to be copied to a destination // chunk. // // The destination_count calculation is a bit subtle. A chunk that has data // that compacts into itself does not count itself as a destination. This // maintains the invariant that a zero count means the chunk is available // and can be claimed and then filled. if (words > 0) { HeapWord* const last_addr = dest_addr + words - 1; const size_t dest_chunk_1 = addr_to_chunk_idx(dest_addr); const size_t dest_chunk_2 = addr_to_chunk_idx(last_addr); #if 0 // Initially assume that the destination chunks will be the same and // adjust the value below if necessary. Under this assumption, if // cur_chunk == dest_chunk_2, then cur_chunk will be compacted completely // into itself. uint destination_count = cur_chunk == dest_chunk_2 ? 0 : 1; if (dest_chunk_1 != dest_chunk_2) { // Destination chunks differ; adjust destination_count. destination_count += 1; // Data from cur_chunk will be copied to the start of dest_chunk_2. _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk); } else if (chunk_offset(dest_addr) == 0) { // Data from cur_chunk will be copied to the start of the destination // chunk. _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk); } #else // Initially assume that the destination chunks will be different and // adjust the value below if necessary. Under this assumption, if // cur_chunk == dest_chunk2, then cur_chunk will be compacted partially // into dest_chunk_1 and partially into itself. uint destination_count = cur_chunk == dest_chunk_2 ? 1 : 2; if (dest_chunk_1 != dest_chunk_2) { // Data from cur_chunk will be copied to the start of dest_chunk_2. _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk); } else { // Destination chunks are the same; adjust destination_count. destination_count -= 1; if (chunk_offset(dest_addr) == 0) { // Data from cur_chunk will be copied to the start of the destination // chunk. _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk); } } #endif // #if 0 _chunk_data[cur_chunk].set_destination_count(destination_count); _chunk_data[cur_chunk].set_data_location(chunk_to_addr(cur_chunk)); dest_addr += words; } ++cur_chunk; } *target_next = dest_addr; return true; } bool ParallelCompactData::partial_obj_ends_in_block(size_t block_index) { HeapWord* block_addr = block_to_addr(block_index); HeapWord* block_end_addr = block_addr + BlockSize; size_t chunk_index = addr_to_chunk_idx(block_addr); HeapWord* partial_obj_end_addr = partial_obj_end(chunk_index); // An object that ends at the end of the block, ends // in the block (the last word of the object is to // the left of the end). if ((block_addr < partial_obj_end_addr) && (partial_obj_end_addr <= block_end_addr)) { return true; } return false; } HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) { HeapWord* result = NULL; if (UseParallelOldGCChunkPointerCalc) { result = chunk_calc_new_pointer(addr); } else { result = block_calc_new_pointer(addr); } return result; } // This method is overly complicated (expensive) to be called // for every reference. // Try to restructure this so that a NULL is returned if // the object is dead. But don't wast the cycles to explicitly check // that it is dead since only live objects should be passed in. HeapWord* ParallelCompactData::chunk_calc_new_pointer(HeapWord* addr) { assert(addr != NULL, "Should detect NULL oop earlier"); assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap"); #ifdef ASSERT if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) { gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr); } #endif assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked"); // Chunk covering the object. size_t chunk_index = addr_to_chunk_idx(addr); const ChunkData* const chunk_ptr = chunk(chunk_index); HeapWord* const chunk_addr = chunk_align_down(addr); assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object"); assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check"); HeapWord* result = chunk_ptr->destination(); // If all the data in the chunk is live, then the new location of the object // can be calculated from the destination of the chunk plus the offset of the // object in the chunk. if (chunk_ptr->data_size() == ChunkSize) { result += pointer_delta(addr, chunk_addr); return result; } // The new location of the object is // chunk destination + // size of the partial object extending onto the chunk + // sizes of the live objects in the Chunk that are to the left of addr const size_t partial_obj_size = chunk_ptr->partial_obj_size(); HeapWord* const search_start = chunk_addr + partial_obj_size; const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr)); result += partial_obj_size + live_to_left; assert(result <= addr, "object cannot move to the right"); return result; } HeapWord* ParallelCompactData::block_calc_new_pointer(HeapWord* addr) { assert(addr != NULL, "Should detect NULL oop earlier"); assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap"); #ifdef ASSERT if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) { gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr); } #endif assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked"); // Chunk covering the object. size_t chunk_index = addr_to_chunk_idx(addr); const ChunkData* const chunk_ptr = chunk(chunk_index); HeapWord* const chunk_addr = chunk_align_down(addr); assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object"); assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check"); HeapWord* result = chunk_ptr->destination(); // If all the data in the chunk is live, then the new location of the object // can be calculated from the destination of the chunk plus the offset of the // object in the chunk. if (chunk_ptr->data_size() == ChunkSize) { result += pointer_delta(addr, chunk_addr); return result; } // The new location of the object is // chunk destination + // block offset + // sizes of the live objects in the Block that are to the left of addr const size_t block_offset = addr_to_block_ptr(addr)->offset(); HeapWord* const search_start = chunk_addr + block_offset; const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap(); size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr)); result += block_offset + live_to_left; assert(result <= addr, "object cannot move to the right"); assert(result == chunk_calc_new_pointer(addr), "Should match"); return result; } klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) { klassOop updated_klass; if (PSParallelCompact::should_update_klass(old_klass)) { updated_klass = (klassOop) calc_new_pointer(old_klass); } else { updated_klass = old_klass; } return updated_klass; } #ifdef ASSERT void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace) { const size_t* const beg = (const size_t*)vspace->committed_low_addr(); const size_t* const end = (const size_t*)vspace->committed_high_addr(); for (const size_t* p = beg; p < end; ++p) { assert(*p == 0, "not zero"); } } void ParallelCompactData::verify_clear() { verify_clear(_chunk_vspace); verify_clear(_block_vspace); } #endif // #ifdef ASSERT #ifdef NOT_PRODUCT ParallelCompactData::ChunkData* debug_chunk(size_t chunk_index) { ParallelCompactData& sd = PSParallelCompact::summary_data(); return sd.chunk(chunk_index); } #endif elapsedTimer PSParallelCompact::_accumulated_time; unsigned int PSParallelCompact::_total_invocations = 0; unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0; jlong PSParallelCompact::_time_of_last_gc = 0; CollectorCounters* PSParallelCompact::_counters = NULL; ParMarkBitMap PSParallelCompact::_mark_bitmap; ParallelCompactData PSParallelCompact::_summary_data; PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure; void PSParallelCompact::IsAliveClosure::do_object(oop p) { ShouldNotReachHere(); } bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); } void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); } void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); } PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true); PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false); void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p, _is_root); } void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); } void PSParallelCompact::FollowStackClosure::do_void() { follow_stack(_compaction_manager); } void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) { mark_and_push(_compaction_manager, p); } void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); } void PSParallelCompact::post_initialize() { ParallelScavengeHeap* heap = gc_heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); MemRegion mr = heap->reserved_region(); _ref_processor = ReferenceProcessor::create_ref_processor( mr, // span true, // atomic_discovery true, // mt_discovery &_is_alive_closure, ParallelGCThreads, ParallelRefProcEnabled); _counters = new CollectorCounters("PSParallelCompact", 1); // Initialize static fields in ParCompactionManager. ParCompactionManager::initialize(mark_bitmap()); } bool PSParallelCompact::initialize() { ParallelScavengeHeap* heap = gc_heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); MemRegion mr = heap->reserved_region(); // Was the old gen get allocated successfully? if (!heap->old_gen()->is_allocated()) { return false; } initialize_space_info(); initialize_dead_wood_limiter(); if (!_mark_bitmap.initialize(mr)) { vm_shutdown_during_initialization("Unable to allocate bit map for " "parallel garbage collection for the requested heap size."); return false; } if (!_summary_data.initialize(mr)) { vm_shutdown_during_initialization("Unable to allocate tables for " "parallel garbage collection for the requested heap size."); return false; } return true; } void PSParallelCompact::initialize_space_info() { memset(&_space_info, 0, sizeof(_space_info)); ParallelScavengeHeap* heap = gc_heap(); PSYoungGen* young_gen = heap->young_gen(); MutableSpace* perm_space = heap->perm_gen()->object_space(); _space_info[perm_space_id].set_space(perm_space); _space_info[old_space_id].set_space(heap->old_gen()->object_space()); _space_info[eden_space_id].set_space(young_gen->eden_space()); _space_info[from_space_id].set_space(young_gen->from_space()); _space_info[to_space_id].set_space(young_gen->to_space()); _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array()); _space_info[old_space_id].set_start_array(heap->old_gen()->start_array()); _space_info[perm_space_id].set_min_dense_prefix(perm_space->top()); if (TraceParallelOldGCDensePrefix) { tty->print_cr("perm min_dense_prefix=" PTR_FORMAT, _space_info[perm_space_id].min_dense_prefix()); } } void PSParallelCompact::initialize_dead_wood_limiter() { const size_t max = 100; _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0; _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0; _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev); DEBUG_ONLY(_dwl_initialized = true;) _dwl_adjustment = normal_distribution(1.0); } // Simple class for storing info about the heap at the start of GC, to be used // after GC for comparison/printing. class PreGCValues { public: PreGCValues() { } PreGCValues(ParallelScavengeHeap* heap) { fill(heap); } void fill(ParallelScavengeHeap* heap) { _heap_used = heap->used(); _young_gen_used = heap->young_gen()->used_in_bytes(); _old_gen_used = heap->old_gen()->used_in_bytes(); _perm_gen_used = heap->perm_gen()->used_in_bytes(); }; size_t heap_used() const { return _heap_used; } size_t young_gen_used() const { return _young_gen_used; } size_t old_gen_used() const { return _old_gen_used; } size_t perm_gen_used() const { return _perm_gen_used; } private: size_t _heap_used; size_t _young_gen_used; size_t _old_gen_used; size_t _perm_gen_used; }; void PSParallelCompact::clear_data_covering_space(SpaceId id) { // At this point, top is the value before GC, new_top() is the value that will // be set at the end of GC. The marking bitmap is cleared to top; nothing // should be marked above top. The summary data is cleared to the larger of // top & new_top. MutableSpace* const space = _space_info[id].space(); HeapWord* const bot = space->bottom(); HeapWord* const top = space->top(); HeapWord* const max_top = MAX2(top, _space_info[id].new_top()); const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot); const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top)); _mark_bitmap.clear_range(beg_bit, end_bit); const size_t beg_chunk = _summary_data.addr_to_chunk_idx(bot); const size_t end_chunk = _summary_data.addr_to_chunk_idx(_summary_data.chunk_align_up(max_top)); _summary_data.clear_range(beg_chunk, end_chunk); } void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values) { // Update the from & to space pointers in space_info, since they are swapped // at each young gen gc. Do the update unconditionally (even though a // promotion failure does not swap spaces) because an unknown number of minor // collections will have swapped the spaces an unknown number of times. TraceTime tm("pre compact", print_phases(), true, gclog_or_tty); ParallelScavengeHeap* heap = gc_heap(); _space_info[from_space_id].set_space(heap->young_gen()->from_space()); _space_info[to_space_id].set_space(heap->young_gen()->to_space()); pre_gc_values->fill(heap); ParCompactionManager::reset(); NOT_PRODUCT(_mark_bitmap.reset_counters()); DEBUG_ONLY(add_obj_count = add_obj_size = 0;) DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;) // Increment the invocation count heap->increment_total_collections(true); // We need to track unique mark sweep invocations as well. _total_invocations++; if (PrintHeapAtGC) { Universe::print_heap_before_gc(); } // Fill in TLABs heap->accumulate_statistics_all_tlabs(); heap->ensure_parsability(true); // retire TLABs if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification gclog_or_tty->print(" VerifyBeforeGC:"); Universe::verify(true); } // Verify object start arrays if (VerifyObjectStartArray && VerifyBeforeGC) { heap->old_gen()->verify_object_start_array(); heap->perm_gen()->verify_object_start_array(); } DEBUG_ONLY(mark_bitmap()->verify_clear();) DEBUG_ONLY(summary_data().verify_clear();) // Have worker threads release resources the next time they run a task. gc_task_manager()->release_all_resources(); } void PSParallelCompact::post_compact() { TraceTime tm("post compact", print_phases(), true, gclog_or_tty); // Clear the marking bitmap and summary data and update top() in each space. for (unsigned int id = perm_space_id; id < last_space_id; ++id) { clear_data_covering_space(SpaceId(id)); _space_info[id].space()->set_top(_space_info[id].new_top()); } MutableSpace* const eden_space = _space_info[eden_space_id].space(); MutableSpace* const from_space = _space_info[from_space_id].space(); MutableSpace* const to_space = _space_info[to_space_id].space(); ParallelScavengeHeap* heap = gc_heap(); bool eden_empty = eden_space->is_empty(); if (!eden_empty) { eden_empty = absorb_live_data_from_eden(heap->size_policy(), heap->young_gen(), heap->old_gen()); } // Update heap occupancy information which is used as input to the soft ref // clearing policy at the next gc. Universe::update_heap_info_at_gc(); bool young_gen_empty = eden_empty && from_space->is_empty() && to_space->is_empty(); BarrierSet* bs = heap->barrier_set(); if (bs->is_a(BarrierSet::ModRef)) { ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs; MemRegion old_mr = heap->old_gen()->reserved(); MemRegion perm_mr = heap->perm_gen()->reserved(); assert(perm_mr.end() <= old_mr.start(), "Generations out of order"); if (young_gen_empty) { modBS->clear(MemRegion(perm_mr.start(), old_mr.end())); } else { modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end())); } } Threads::gc_epilogue(); CodeCache::gc_epilogue(); COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); ref_processor()->enqueue_discovered_references(NULL); if (ZapUnusedHeapArea) { heap->gen_mangle_unused_area(); } // Update time of last GC reset_millis_since_last_gc(); } HeapWord* PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id, bool maximum_compaction) { const size_t chunk_size = ParallelCompactData::ChunkSize; const ParallelCompactData& sd = summary_data(); const MutableSpace* const space = _space_info[id].space(); HeapWord* const top_aligned_up = sd.chunk_align_up(space->top()); const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(space->bottom()); const ChunkData* const end_cp = sd.addr_to_chunk_ptr(top_aligned_up); // Skip full chunks at the beginning of the space--they are necessarily part // of the dense prefix. size_t full_count = 0; const ChunkData* cp; for (cp = beg_cp; cp < end_cp && cp->data_size() == chunk_size; ++cp) { ++full_count; } assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval; if (maximum_compaction || cp == end_cp || interval_ended) { _maximum_compaction_gc_num = total_invocations(); return sd.chunk_to_addr(cp); } HeapWord* const new_top = _space_info[id].new_top(); const size_t space_live = pointer_delta(new_top, space->bottom()); const size_t space_used = space->used_in_words(); const size_t space_capacity = space->capacity_in_words(); const double cur_density = double(space_live) / space_capacity; const double deadwood_density = (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density; const size_t deadwood_goal = size_t(space_capacity * deadwood_density); if (TraceParallelOldGCDensePrefix) { tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT, cur_density, deadwood_density, deadwood_goal); tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " "space_cap=" SIZE_FORMAT, space_live, space_used, space_capacity); } // XXX - Use binary search? HeapWord* dense_prefix = sd.chunk_to_addr(cp); const ChunkData* full_cp = cp; const ChunkData* const top_cp = sd.addr_to_chunk_ptr(space->top() - 1); while (cp < end_cp) { HeapWord* chunk_destination = cp->destination(); const size_t cur_deadwood = pointer_delta(dense_prefix, chunk_destination); if (TraceParallelOldGCDensePrefix && Verbose) { tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " " "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8), sd.chunk(cp), chunk_destination, dense_prefix, cur_deadwood); } if (cur_deadwood >= deadwood_goal) { // Found the chunk that has the correct amount of deadwood to the left. // This typically occurs after crossing a fairly sparse set of chunks, so // iterate backwards over those sparse chunks, looking for the chunk that // has the lowest density of live objects 'to the right.' size_t space_to_left = sd.chunk(cp) * chunk_size; size_t live_to_left = space_to_left - cur_deadwood; size_t space_to_right = space_capacity - space_to_left; size_t live_to_right = space_live - live_to_left; double density_to_right = double(live_to_right) / space_to_right; while (cp > full_cp) { --cp; const size_t prev_chunk_live_to_right = live_to_right - cp->data_size(); const size_t prev_chunk_space_to_right = space_to_right + chunk_size; double prev_chunk_density_to_right = double(prev_chunk_live_to_right) / prev_chunk_space_to_right; if (density_to_right <= prev_chunk_density_to_right) { return dense_prefix; } if (TraceParallelOldGCDensePrefix && Verbose) { tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f " "pc_d2r=%10.8f", sd.chunk(cp), density_to_right, prev_chunk_density_to_right); } dense_prefix -= chunk_size; live_to_right = prev_chunk_live_to_right; space_to_right = prev_chunk_space_to_right; density_to_right = prev_chunk_density_to_right; } return dense_prefix; } dense_prefix += chunk_size; ++cp; } return dense_prefix; } #ifndef PRODUCT void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm, const SpaceId id, const bool maximum_compaction, HeapWord* const addr) { const size_t chunk_idx = summary_data().addr_to_chunk_idx(addr); ChunkData* const cp = summary_data().chunk(chunk_idx); const MutableSpace* const space = _space_info[id].space(); HeapWord* const new_top = _space_info[id].new_top(); const size_t space_live = pointer_delta(new_top, space->bottom()); const size_t dead_to_left = pointer_delta(addr, cp->destination()); const size_t space_cap = space->capacity_in_words(); const double dead_to_left_pct = double(dead_to_left) / space_cap; const size_t live_to_right = new_top - cp->destination(); const size_t dead_to_right = space->top() - addr - live_to_right; tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " " "spl=" SIZE_FORMAT " " "d2l=" SIZE_FORMAT " d2l%%=%6.4f " "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT " ratio=%10.8f", algorithm, addr, chunk_idx, space_live, dead_to_left, dead_to_left_pct, dead_to_right, live_to_right, double(dead_to_right) / live_to_right); } #endif // #ifndef PRODUCT // Return a fraction indicating how much of the generation can be treated as // "dead wood" (i.e., not reclaimed). The function uses a normal distribution // based on the density of live objects in the generation to determine a limit, // which is then adjusted so the return value is min_percent when the density is // 1. // // The following table shows some return values for a different values of the // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and // min_percent is 1. // // fraction allowed as dead wood // ----------------------------------------------------------------- // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95 // ------- ---------- ---------- ---------- ---------- ---------- ---------- // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent) { assert(_dwl_initialized, "uninitialized"); // The raw limit is the value of the normal distribution at x = density. const double raw_limit = normal_distribution(density); // Adjust the raw limit so it becomes the minimum when the density is 1. // // First subtract the adjustment value (which is simply the precomputed value // normal_distribution(1.0)); this yields a value of 0 when the density is 1. // Then add the minimum value, so the minimum is returned when the density is // 1. Finally, prevent negative values, which occur when the mean is not 0.5. const double min = double(min_percent) / 100.0; const double limit = raw_limit - _dwl_adjustment + min; return MAX2(limit, 0.0); } ParallelCompactData::ChunkData* PSParallelCompact::first_dead_space_chunk(const ChunkData* beg, const ChunkData* end) { const size_t chunk_size = ParallelCompactData::ChunkSize; ParallelCompactData& sd = summary_data(); size_t left = sd.chunk(beg); size_t right = end > beg ? sd.chunk(end) - 1 : left; // Binary search. while (left < right) { // Equivalent to (left + right) / 2, but does not overflow. const size_t middle = left + (right - left) / 2; ChunkData* const middle_ptr = sd.chunk(middle); HeapWord* const dest = middle_ptr->destination(); HeapWord* const addr = sd.chunk_to_addr(middle); assert(dest != NULL, "sanity"); assert(dest <= addr, "must move left"); if (middle > left && dest < addr) { right = middle - 1; } else if (middle < right && middle_ptr->data_size() == chunk_size) { left = middle + 1; } else { return middle_ptr; } } return sd.chunk(left); } ParallelCompactData::ChunkData* PSParallelCompact::dead_wood_limit_chunk(const ChunkData* beg, const ChunkData* end, size_t dead_words) { ParallelCompactData& sd = summary_data(); size_t left = sd.chunk(beg); size_t right = end > beg ? sd.chunk(end) - 1 : left; // Binary search. while (left < right) { // Equivalent to (left + right) / 2, but does not overflow. const size_t middle = left + (right - left) / 2; ChunkData* const middle_ptr = sd.chunk(middle); HeapWord* const dest = middle_ptr->destination(); HeapWord* const addr = sd.chunk_to_addr(middle); assert(dest != NULL, "sanity"); assert(dest <= addr, "must move left"); const size_t dead_to_left = pointer_delta(addr, dest); if (middle > left && dead_to_left > dead_words) { right = middle - 1; } else if (middle < right && dead_to_left < dead_words) { left = middle + 1; } else { return middle_ptr; } } return sd.chunk(left); } // The result is valid during the summary phase, after the initial summarization // of each space into itself, and before final summarization. inline double PSParallelCompact::reclaimed_ratio(const ChunkData* const cp, HeapWord* const bottom, HeapWord* const top, HeapWord* const new_top) { ParallelCompactData& sd = summary_data(); assert(cp != NULL, "sanity"); assert(bottom != NULL, "sanity"); assert(top != NULL, "sanity"); assert(new_top != NULL, "sanity"); assert(top >= new_top, "summary data problem?"); assert(new_top > bottom, "space is empty; should not be here"); assert(new_top >= cp->destination(), "sanity"); assert(top >= sd.chunk_to_addr(cp), "sanity"); HeapWord* const destination = cp->destination(); const size_t dense_prefix_live = pointer_delta(destination, bottom); const size_t compacted_region_live = pointer_delta(new_top, destination); const size_t compacted_region_used = pointer_delta(top, sd.chunk_to_addr(cp)); const size_t reclaimable = compacted_region_used - compacted_region_live; const double divisor = dense_prefix_live + 1.25 * compacted_region_live; return double(reclaimable) / divisor; } // Return the address of the end of the dense prefix, a.k.a. the start of the // compacted region. The address is always on a chunk boundary. // // Completely full chunks at the left are skipped, since no compaction can occur // in those chunks. Then the maximum amount of dead wood to allow is computed, // based on the density (amount live / capacity) of the generation; the chunk // with approximately that amount of dead space to the left is identified as the // limit chunk. Chunks between the last completely full chunk and the limit // chunk are scanned and the one that has the best (maximum) reclaimed_ratio() // is selected. HeapWord* PSParallelCompact::compute_dense_prefix(const SpaceId id, bool maximum_compaction) { const size_t chunk_size = ParallelCompactData::ChunkSize; const ParallelCompactData& sd = summary_data(); const MutableSpace* const space = _space_info[id].space(); HeapWord* const top = space->top(); HeapWord* const top_aligned_up = sd.chunk_align_up(top); HeapWord* const new_top = _space_info[id].new_top(); HeapWord* const new_top_aligned_up = sd.chunk_align_up(new_top); HeapWord* const bottom = space->bottom(); const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(bottom); const ChunkData* const top_cp = sd.addr_to_chunk_ptr(top_aligned_up); const ChunkData* const new_top_cp = sd.addr_to_chunk_ptr(new_top_aligned_up); // Skip full chunks at the beginning of the space--they are necessarily part // of the dense prefix. const ChunkData* const full_cp = first_dead_space_chunk(beg_cp, new_top_cp); assert(full_cp->destination() == sd.chunk_to_addr(full_cp) || space->is_empty(), "no dead space allowed to the left"); assert(full_cp->data_size() < chunk_size || full_cp == new_top_cp - 1, "chunk must have dead space"); // The gc number is saved whenever a maximum compaction is done, and used to // determine when the maximum compaction interval has expired. This avoids // successive max compactions for different reasons. assert(total_invocations() >= _maximum_compaction_gc_num, "sanity"); const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num; const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval || total_invocations() == HeapFirstMaximumCompactionCount; if (maximum_compaction || full_cp == top_cp || interval_ended) { _maximum_compaction_gc_num = total_invocations(); return sd.chunk_to_addr(full_cp); } const size_t space_live = pointer_delta(new_top, bottom); const size_t space_used = space->used_in_words(); const size_t space_capacity = space->capacity_in_words(); const double density = double(space_live) / double(space_capacity); const size_t min_percent_free = id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio; const double limiter = dead_wood_limiter(density, min_percent_free); const size_t dead_wood_max = space_used - space_live; const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter), dead_wood_max); if (TraceParallelOldGCDensePrefix) { tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " " "space_cap=" SIZE_FORMAT, space_live, space_used, space_capacity); tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f " "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT, density, min_percent_free, limiter, dead_wood_max, dead_wood_limit); } // Locate the chunk with the desired amount of dead space to the left. const ChunkData* const limit_cp = dead_wood_limit_chunk(full_cp, top_cp, dead_wood_limit); // Scan from the first chunk with dead space to the limit chunk and find the // one with the best (largest) reclaimed ratio. double best_ratio = 0.0; const ChunkData* best_cp = full_cp; for (const ChunkData* cp = full_cp; cp < limit_cp; ++cp) { double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top); if (tmp_ratio > best_ratio) { best_cp = cp; best_ratio = tmp_ratio; } } #if 0 // Something to consider: if the chunk with the best ratio is 'close to' the // first chunk w/free space, choose the first chunk with free space // ("first-free"). The first-free chunk is usually near the start of the // heap, which means we are copying most of the heap already, so copy a bit // more to get complete compaction. if (pointer_delta(best_cp, full_cp, sizeof(ChunkData)) < 4) { _maximum_compaction_gc_num = total_invocations(); best_cp = full_cp; } #endif // #if 0 return sd.chunk_to_addr(best_cp); } void PSParallelCompact::summarize_spaces_quick() { for (unsigned int i = 0; i < last_space_id; ++i) { const MutableSpace* space = _space_info[i].space(); bool result = _summary_data.summarize(space->bottom(), space->end(), space->bottom(), space->top(), _space_info[i].new_top_addr()); assert(result, "should never fail"); _space_info[i].set_dense_prefix(space->bottom()); } } void PSParallelCompact::fill_dense_prefix_end(SpaceId id) { HeapWord* const dense_prefix_end = dense_prefix(id); const ChunkData* chunk = _summary_data.addr_to_chunk_ptr(dense_prefix_end); const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end); if (dead_space_crosses_boundary(chunk, dense_prefix_bit)) { // Only enough dead space is filled so that any remaining dead space to the // left is larger than the minimum filler object. (The remainder is filled // during the copy/update phase.) // // The size of the dead space to the right of the boundary is not a // concern, since compaction will be able to use whatever space is // available. // // Here '||' is the boundary, 'x' represents a don't care bit and a box // surrounds the space to be filled with an object. // // In the 32-bit VM, each bit represents two 32-bit words: // +---+ // a) beg_bits: ... x x x | 0 | || 0 x x ... // end_bits: ... x x x | 0 | || 0 x x ... // +---+ // // In the 64-bit VM, each bit represents one 64-bit word: // +------------+ // b) beg_bits: ... x x x | 0 || 0 | x x ... // end_bits: ... x x 1 | 0 || 0 | x x ... // +------------+ // +-------+ // c) beg_bits: ... x x | 0 0 | || 0 x x ... // end_bits: ... x 1 | 0 0 | || 0 x x ... // +-------+ // +-----------+ // d) beg_bits: ... x | 0 0 0 | || 0 x x ... // end_bits: ... 1 | 0 0 0 | || 0 x x ... // +-----------+ // +-------+ // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ... // end_bits: ... 0 0 | 0 0 | || 0 x x ... // +-------+ // Initially assume case a, c or e will apply. size_t obj_len = (size_t)oopDesc::header_size(); HeapWord* obj_beg = dense_prefix_end - obj_len; #ifdef _LP64 if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) { // Case b above. obj_beg = dense_prefix_end - 1; } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) && _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) { // Case d above. obj_beg = dense_prefix_end - 3; obj_len = 3; } #endif // #ifdef _LP64 MemRegion region(obj_beg, obj_len); SharedHeap::fill_region_with_object(region); _mark_bitmap.mark_obj(obj_beg, obj_len); _summary_data.add_obj(obj_beg, obj_len); assert(start_array(id) != NULL, "sanity"); start_array(id)->allocate_block(obj_beg); } } void PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction) { assert(id < last_space_id, "id out of range"); assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(), "should have been set in summarize_spaces_quick()"); const MutableSpace* space = _space_info[id].space(); if (_space_info[id].new_top() != space->bottom()) { HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction); _space_info[id].set_dense_prefix(dense_prefix_end); #ifndef PRODUCT if (TraceParallelOldGCDensePrefix) { print_dense_prefix_stats("ratio", id, maximum_compaction, dense_prefix_end); HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction); print_dense_prefix_stats("density", id, maximum_compaction, addr); } #endif // #ifndef PRODUCT // If dead space crosses the dense prefix boundary, it is (at least // partially) filled with a dummy object, marked live and added to the // summary data. This simplifies the copy/update phase and must be done // before the final locations of objects are determined, to prevent leaving // a fragment of dead space that is too small to fill with an object. if (!maximum_compaction && dense_prefix_end != space->bottom()) { fill_dense_prefix_end(id); } // Compute the destination of each Chunk, and thus each object. _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end); _summary_data.summarize(dense_prefix_end, space->end(), dense_prefix_end, space->top(), _space_info[id].new_top_addr()); } if (TraceParallelOldGCSummaryPhase) { const size_t chunk_size = ParallelCompactData::ChunkSize; HeapWord* const dense_prefix_end = _space_info[id].dense_prefix(); const size_t dp_chunk = _summary_data.addr_to_chunk_idx(dense_prefix_end); const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom()); HeapWord* const new_top = _space_info[id].new_top(); const HeapWord* nt_aligned_up = _summary_data.chunk_align_up(new_top); const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end); tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " " "dp_chunk=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " " "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT, id, space->capacity_in_words(), dense_prefix_end, dp_chunk, dp_words / chunk_size, cr_words / chunk_size, new_top); } } void PSParallelCompact::summary_phase(ParCompactionManager* cm, bool maximum_compaction) { EventMark m("2 summarize"); TraceTime tm("summary phase", print_phases(), true, gclog_or_tty); // trace("2"); #ifdef ASSERT if (VerifyParallelOldWithMarkSweep && (PSParallelCompact::total_invocations() % VerifyParallelOldWithMarkSweepInterval) == 0) { verify_mark_bitmap(_mark_bitmap); } if (TraceParallelOldGCMarkingPhase) { tty->print_cr("add_obj_count=" SIZE_FORMAT " " "add_obj_bytes=" SIZE_FORMAT, add_obj_count, add_obj_size * HeapWordSize); tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " " "mark_bitmap_bytes=" SIZE_FORMAT, mark_bitmap_count, mark_bitmap_size * HeapWordSize); } #endif // #ifdef ASSERT // Quick summarization of each space into itself, to see how much is live. summarize_spaces_quick(); if (TraceParallelOldGCSummaryPhase) { tty->print_cr("summary_phase: after summarizing each space to self"); Universe::print(); NOT_PRODUCT(print_chunk_ranges()); if (Verbose) { NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info)); } } // The amount of live data that will end up in old space (assuming it fits). size_t old_space_total_live = 0; unsigned int id; for (id = old_space_id; id < last_space_id; ++id) { old_space_total_live += pointer_delta(_space_info[id].new_top(), _space_info[id].space()->bottom()); } const MutableSpace* old_space = _space_info[old_space_id].space(); if (old_space_total_live > old_space->capacity_in_words()) { // XXX - should also try to expand maximum_compaction = true; } else if (!UseParallelOldGCDensePrefix) { maximum_compaction = true; } // Permanent and Old generations. summarize_space(perm_space_id, maximum_compaction); summarize_space(old_space_id, maximum_compaction); // Summarize the remaining spaces (those in the young gen) into old space. If // the live data from a space doesn't fit, the existing summarization is left // intact, so the data is compacted down within the space itself. HeapWord** new_top_addr = _space_info[old_space_id].new_top_addr(); HeapWord* const target_space_end = old_space->end(); for (id = eden_space_id; id < last_space_id; ++id) { const MutableSpace* space = _space_info[id].space(); const size_t live = pointer_delta(_space_info[id].new_top(), space->bottom()); const size_t available = pointer_delta(target_space_end, *new_top_addr); if (live > 0 && live <= available) { // All the live data will fit. if (TraceParallelOldGCSummaryPhase) { tty->print_cr("summarizing %d into old_space @ " PTR_FORMAT, id, *new_top_addr); } _summary_data.summarize(*new_top_addr, target_space_end, space->bottom(), space->top(), new_top_addr); // Clear the source_chunk field for each chunk in the space. HeapWord* const new_top = _space_info[id].new_top(); HeapWord* const clear_end = _summary_data.chunk_align_up(new_top); ChunkData* beg_chunk = _summary_data.addr_to_chunk_ptr(space->bottom()); ChunkData* end_chunk = _summary_data.addr_to_chunk_ptr(clear_end); while (beg_chunk < end_chunk) { beg_chunk->set_source_chunk(0); ++beg_chunk; } // Reset the new_top value for the space. _space_info[id].set_new_top(space->bottom()); } } // Fill in the block data after any changes to the chunks have // been made. #ifdef ASSERT summarize_blocks(cm, perm_space_id); summarize_blocks(cm, old_space_id); #else if (!UseParallelOldGCChunkPointerCalc) { summarize_blocks(cm, perm_space_id); summarize_blocks(cm, old_space_id); } #endif if (TraceParallelOldGCSummaryPhase) { tty->print_cr("summary_phase: after final summarization"); Universe::print(); NOT_PRODUCT(print_chunk_ranges()); if (Verbose) { NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info)); } } } // Fill in the BlockData. // Iterate over the spaces and within each space iterate over // the chunks and fill in the BlockData for each chunk. void PSParallelCompact::summarize_blocks(ParCompactionManager* cm, SpaceId first_compaction_space_id) { #if 0 DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(1);) for (SpaceId cur_space_id = first_compaction_space_id; cur_space_id != last_space_id; cur_space_id = next_compaction_space_id(cur_space_id)) { // Iterate over the chunks in the space size_t start_chunk_index = _summary_data.addr_to_chunk_idx(space(cur_space_id)->bottom()); BitBlockUpdateClosure bbu(mark_bitmap(), cm, start_chunk_index); // Iterate over blocks. for (size_t chunk_index = start_chunk_index; chunk_index < _summary_data.chunk_count() && _summary_data.chunk_to_addr(chunk_index) < space(cur_space_id)->top(); chunk_index++) { // Reset the closure for the new chunk. Note that the closure // maintains some data that does not get reset for each chunk // so a new instance of the closure is no appropriate. bbu.reset_chunk(chunk_index); // Start the iteration with the first live object. This // may return the end of the chunk. That is acceptable since // it will properly limit the iterations. ParMarkBitMap::idx_t left_offset = mark_bitmap()->addr_to_bit( _summary_data.first_live_or_end_in_chunk(chunk_index)); // End the iteration at the end of the chunk. HeapWord* chunk_addr = _summary_data.chunk_to_addr(chunk_index); HeapWord* chunk_end = chunk_addr + ParallelCompactData::ChunkSize; ParMarkBitMap::idx_t right_offset = mark_bitmap()->addr_to_bit(chunk_end); // Blocks that have not objects starting in them can be // skipped because their data will never be used. if (left_offset < right_offset) { // Iterate through the objects in the chunk. ParMarkBitMap::idx_t last_offset = mark_bitmap()->pair_iterate(&bbu, left_offset, right_offset); // If last_offset is less than right_offset, then the iterations // terminated while it was looking for an end bit. "last_offset" // is then the offset for the last start bit. In this situation // the "offset" field for the next block to the right (_cur_block + 1) // will not have been update although there may be live data // to the left of the chunk. size_t cur_block_plus_1 = bbu.cur_block() + 1; HeapWord* cur_block_plus_1_addr = _summary_data.block_to_addr(bbu.cur_block()) + ParallelCompactData::BlockSize; HeapWord* last_offset_addr = mark_bitmap()->bit_to_addr(last_offset); #if 1 // This code works. The else doesn't but should. Why does it? // The current block (cur_block()) has already been updated. // The last block that may need to be updated is either the // next block (current block + 1) or the block where the // last object starts (which can be greater than the // next block if there were no objects found in intervening // blocks). size_t last_block = MAX2(bbu.cur_block() + 1, _summary_data.addr_to_block_idx(last_offset_addr)); #else // The current block has already been updated. The only block // that remains to be updated is the block where the last // object in the chunk starts. size_t last_block = _summary_data.addr_to_block_idx(last_offset_addr); #endif assert_bit_is_start(last_offset); assert((last_block == _summary_data.block_count()) || (_summary_data.block(last_block)->raw_offset() == 0), "Should not have been set"); // Is the last block still in the current chunk? If still // in this chunk, update the last block (the counting that // included the current block is meant for the offset of the last // block). If not in this chunk, do nothing. Should not // update a block in the next chunk. if (ParallelCompactData::chunk_contains_block(bbu.chunk_index(), last_block)) { if (last_offset < right_offset) { // The last object started in this chunk but ends beyond // this chunk. Update the block for this last object. assert(mark_bitmap()->is_marked(last_offset), "Should be marked"); // No end bit was found. The closure takes care of // the cases where // an objects crosses over into the next block // an objects starts and ends in the next block // It does not handle the case where an object is // the first object in a later block and extends // past the end of the chunk (i.e., the closure // only handles complete objects that are in the range // it is given). That object is handed back here // for any special consideration necessary. // // Is the first bit in the last block a start or end bit? // // If the partial object ends in the last block L, // then the 1st bit in L may be an end bit. // // Else does the last object start in a block after the current // block? A block AA will already have been updated if an // object ends in the next block AA+1. An object found to end in // the AA+1 is the trigger that updates AA. Objects are being // counted in the current block for updaing a following // block. An object may start in later block // block but may extend beyond the last block in the chunk. // Updates are only done when the end of an object has been // found. If the last object (covered by block L) starts // beyond the current block, then no object ends in L (otherwise // L would be the current block). So the first bit in L is // a start bit. // // Else the last objects start in the current block and ends // beyond the chunk. The current block has already been // updated and there is no later block (with an object // starting in it) that needs to be updated. // if (_summary_data.partial_obj_ends_in_block(last_block)) { _summary_data.block(last_block)->set_end_bit_offset( bbu.live_data_left()); } else if (last_offset_addr >= cur_block_plus_1_addr) { // The start of the object is on a later block // (to the right of the current block and there are no // complete live objects to the left of this last object // within the chunk. // The first bit in the block is for the start of the // last object. _summary_data.block(last_block)->set_start_bit_offset( bbu.live_data_left()); } else { // The start of the last object was found in // the current chunk (which has already // been updated). assert(bbu.cur_block() == _summary_data.addr_to_block_idx(last_offset_addr), "Should be a block already processed"); } #ifdef ASSERT // Is there enough block information to find this object? // The destination of the chunk has not been set so the // values returned by calc_new_pointer() and // block_calc_new_pointer() will only be // offsets. But they should agree. HeapWord* moved_obj_with_chunks = _summary_data.chunk_calc_new_pointer(last_offset_addr); HeapWord* moved_obj_with_blocks = _summary_data.calc_new_pointer(last_offset_addr); assert(moved_obj_with_chunks == moved_obj_with_blocks, "Block calculation is wrong"); #endif } else if (last_block < _summary_data.block_count()) { // Iterations ended looking for a start bit (but // did not run off the end of the block table). _summary_data.block(last_block)->set_start_bit_offset( bbu.live_data_left()); } } #ifdef ASSERT // Is there enough block information to find this object? HeapWord* left_offset_addr = mark_bitmap()->bit_to_addr(left_offset); HeapWord* moved_obj_with_chunks = _summary_data.calc_new_pointer(left_offset_addr); HeapWord* moved_obj_with_blocks = _summary_data.calc_new_pointer(left_offset_addr); assert(moved_obj_with_chunks == moved_obj_with_blocks, "Block calculation is wrong"); #endif // Is there another block after the end of this chunk? #ifdef ASSERT if (last_block < _summary_data.block_count()) { // No object may have been found in a block. If that // block is at the end of the chunk, the iteration will // terminate without incrementing the current block so // that the current block is not the last block in the // chunk. That situation precludes asserting that the // current block is the last block in the chunk. Assert // the lesser condition that the current block does not // exceed the chunk. assert(_summary_data.block_to_addr(last_block) <= (_summary_data.chunk_to_addr(chunk_index) + ParallelCompactData::ChunkSize), "Chunk and block inconsistency"); assert(last_offset <= right_offset, "Iteration over ran end"); } #endif } #ifdef ASSERT if (PrintGCDetails && Verbose) { if (_summary_data.chunk(chunk_index)->partial_obj_size() == 1) { size_t first_block = chunk_index / ParallelCompactData::BlocksPerChunk; gclog_or_tty->print_cr("first_block " PTR_FORMAT " _offset " PTR_FORMAT "_first_is_start_bit %d", first_block, _summary_data.block(first_block)->raw_offset(), _summary_data.block(first_block)->first_is_start_bit()); } } #endif } } DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(16);) #endif // #if 0 } // This method should contain all heap-specific policy for invoking a full // collection. invoke_no_policy() will only attempt to compact the heap; it // will do nothing further. If we need to bail out for policy reasons, scavenge // before full gc, or any other specialized behavior, it needs to be added here. // // Note that this method should only be called from the vm_thread while at a // safepoint. void PSParallelCompact::invoke(bool maximum_heap_compaction) { assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); ParallelScavengeHeap* heap = gc_heap(); GCCause::Cause gc_cause = heap->gc_cause(); assert(!heap->is_gc_active(), "not reentrant"); PSAdaptiveSizePolicy* policy = heap->size_policy(); // Before each allocation/collection attempt, find out from the // policy object if GCs are, on the whole, taking too long. If so, // bail out without attempting a collection. The exceptions are // for explicitly requested GC's. if (!policy->gc_time_limit_exceeded() || GCCause::is_user_requested_gc(gc_cause) || GCCause::is_serviceability_requested_gc(gc_cause)) { IsGCActiveMark mark; if (ScavengeBeforeFullGC) { PSScavenge::invoke_no_policy(); } PSParallelCompact::invoke_no_policy(maximum_heap_compaction); } } bool ParallelCompactData::chunk_contains(size_t chunk_index, HeapWord* addr) { size_t addr_chunk_index = addr_to_chunk_idx(addr); return chunk_index == addr_chunk_index; } bool ParallelCompactData::chunk_contains_block(size_t chunk_index, size_t block_index) { size_t first_block_in_chunk = chunk_index * BlocksPerChunk; size_t last_block_in_chunk = (chunk_index + 1) * BlocksPerChunk - 1; return (first_block_in_chunk <= block_index) && (block_index <= last_block_in_chunk); } // This method contains no policy. You should probably // be calling invoke() instead. void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) { assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); assert(ref_processor() != NULL, "Sanity"); if (GC_locker::check_active_before_gc()) { return; } TimeStamp marking_start; TimeStamp compaction_start; TimeStamp collection_exit; ParallelScavengeHeap* heap = gc_heap(); GCCause::Cause gc_cause = heap->gc_cause(); PSYoungGen* young_gen = heap->young_gen(); PSOldGen* old_gen = heap->old_gen(); PSPermGen* perm_gen = heap->perm_gen(); PSAdaptiveSizePolicy* size_policy = heap->size_policy(); if (ZapUnusedHeapArea) { // Save information needed to minimize mangling heap->record_gen_tops_before_GC(); } _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes; // Make sure data structures are sane, make the heap parsable, and do other // miscellaneous bookkeeping. PreGCValues pre_gc_values; pre_compact(&pre_gc_values); // Get the compaction manager reserved for the VM thread. ParCompactionManager* const vmthread_cm = ParCompactionManager::manager_array(gc_task_manager()->workers()); // Place after pre_compact() where the number of invocations is incremented. AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); { ResourceMark rm; HandleMark hm; const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc; // This is useful for debugging but don't change the output the // the customer sees. const char* gc_cause_str = "Full GC"; if (is_system_gc && PrintGCDetails) { gc_cause_str = "Full GC (System)"; } gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty); TraceCollectorStats tcs(counters()); TraceMemoryManagerStats tms(true /* Full GC */); if (TraceGen1Time) accumulated_time()->start(); // Let the size policy know we're starting size_policy->major_collection_begin(); // When collecting the permanent generation methodOops may be moving, // so we either have to flush all bcp data or convert it into bci. CodeCache::gc_prologue(); Threads::gc_prologue(); NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); COMPILER2_PRESENT(DerivedPointerTable::clear()); ref_processor()->enable_discovery(); bool marked_for_unloading = false; marking_start.update(); marking_phase(vmthread_cm, maximum_heap_compaction); #ifndef PRODUCT if (TraceParallelOldGCMarkingPhase) { gclog_or_tty->print_cr("marking_phase: cas_tries %d cas_retries %d " "cas_by_another %d", mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(), mark_bitmap()->cas_by_another()); } #endif // #ifndef PRODUCT #ifdef ASSERT if (VerifyParallelOldWithMarkSweep && (PSParallelCompact::total_invocations() % VerifyParallelOldWithMarkSweepInterval) == 0) { gclog_or_tty->print_cr("Verify marking with mark_sweep_phase1()"); if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("mark_sweep_phase1:"); } // Clear the discovered lists so that discovered objects // don't look like they have been discovered twice. ref_processor()->clear_discovered_references(); PSMarkSweep::allocate_stacks(); MemRegion mr = Universe::heap()->reserved_region(); PSMarkSweep::ref_processor()->enable_discovery(); PSMarkSweep::mark_sweep_phase1(maximum_heap_compaction); } #endif bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc; summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc); #ifdef ASSERT if (VerifyParallelOldWithMarkSweep && (PSParallelCompact::total_invocations() % VerifyParallelOldWithMarkSweepInterval) == 0) { if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("mark_sweep_phase2:"); } PSMarkSweep::mark_sweep_phase2(); } #endif 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(); #ifdef ASSERT if (VerifyParallelOldWithMarkSweep && (PSParallelCompact::total_invocations() % VerifyParallelOldWithMarkSweepInterval) == 0) { // Do a separate verify phase so that the verify // code can use the the forwarding pointers to // check the new pointer calculation. The restore_marks() // has to be done before the real compact. vmthread_cm->set_action(ParCompactionManager::VerifyUpdate); compact_perm(vmthread_cm); compact_serial(vmthread_cm); vmthread_cm->set_action(ParCompactionManager::ResetObjects); compact_perm(vmthread_cm); compact_serial(vmthread_cm); vmthread_cm->set_action(ParCompactionManager::UpdateAndCopy); // For debugging only PSMarkSweep::restore_marks(); PSMarkSweep::deallocate_stacks(); } #endif compaction_start.update(); // Does the perm gen always have to be done serially because // klasses are used in the update of an object? compact_perm(vmthread_cm); if (UseParallelOldGCCompacting) { compact(); } else { compact_serial(vmthread_cm); } // Reset the mark bitmap, summary data, and do other bookkeeping. Must be // done before resizing. post_compact(); // Let the size policy know we're done size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause); if (UseAdaptiveSizePolicy) { if (PrintAdaptiveSizePolicy) { gclog_or_tty->print("AdaptiveSizeStart: "); gclog_or_tty->stamp(); gclog_or_tty->print_cr(" collection: %d ", heap->total_collections()); if (Verbose) { gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" " perm_gen_capacity: %d ", old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), perm_gen->capacity_in_bytes()); } } // Don't check if the size_policy is ready here. Let // the size_policy check that internally. if (UseAdaptiveGenerationSizePolicyAtMajorCollection && ((gc_cause != GCCause::_java_lang_system_gc) || UseAdaptiveSizePolicyWithSystemGC)) { // Calculate optimal free space amounts assert(young_gen->max_size() > young_gen->from_space()->capacity_in_bytes() + young_gen->to_space()->capacity_in_bytes(), "Sizes of space in young gen are out-of-bounds"); size_t max_eden_size = young_gen->max_size() - young_gen->from_space()->capacity_in_bytes() - young_gen->to_space()->capacity_in_bytes(); size_policy->compute_generation_free_space( young_gen->used_in_bytes(), young_gen->eden_space()->used_in_bytes(), old_gen->used_in_bytes(), perm_gen->used_in_bytes(), young_gen->eden_space()->capacity_in_bytes(), old_gen->max_gen_size(), max_eden_size, true /* full gc*/, gc_cause); heap->resize_old_gen( size_policy->calculated_old_free_size_in_bytes()); // Don't resize the young generation at an major collection. A // desired young generation size may have been calculated but // resizing the young generation complicates the code because the // resizing of the old generation may have moved the boundary // between the young generation and the old generation. Let the // young generation resizing happen at the minor collections. } if (PrintAdaptiveSizePolicy) { gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", heap->total_collections()); } } if (UsePerfData) { PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); counters->update_counters(); counters->update_old_capacity(old_gen->capacity_in_bytes()); counters->update_young_capacity(young_gen->capacity_in_bytes()); } heap->resize_all_tlabs(); // We collected the perm gen, so we'll resize it here. perm_gen->compute_new_size(pre_gc_values.perm_gen_used()); if (TraceGen1Time) accumulated_time()->stop(); if (PrintGC) { if (PrintGCDetails) { // No GC timestamp here. This is after GC so it would be confusing. young_gen->print_used_change(pre_gc_values.young_gen_used()); old_gen->print_used_change(pre_gc_values.old_gen_used()); heap->print_heap_change(pre_gc_values.heap_used()); // Print perm gen last (print_heap_change() excludes the perm gen). perm_gen->print_used_change(pre_gc_values.perm_gen_used()); } else { heap->print_heap_change(pre_gc_values.heap_used()); } } // Track memory usage and detect low memory MemoryService::track_memory_usage(); heap->update_counters(); if (PrintGCDetails) { if (size_policy->print_gc_time_limit_would_be_exceeded()) { if (size_policy->gc_time_limit_exceeded()) { gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit " "of %d%%", GCTimeLimit); } else { gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit " "of %d%%", GCTimeLimit); } } size_policy->set_print_gc_time_limit_would_be_exceeded(false); } } if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { HandleMark hm; // Discard invalid handles created during verification gclog_or_tty->print(" VerifyAfterGC:"); Universe::verify(false); } // Re-verify object start arrays if (VerifyObjectStartArray && VerifyAfterGC) { old_gen->verify_object_start_array(); perm_gen->verify_object_start_array(); } if (ZapUnusedHeapArea) { old_gen->object_space()->check_mangled_unused_area_complete(); perm_gen->object_space()->check_mangled_unused_area_complete(); } NOT_PRODUCT(ref_processor()->verify_no_references_recorded()); collection_exit.update(); if (PrintHeapAtGC) { Universe::print_heap_after_gc(); } if (PrintGCTaskTimeStamps) { gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, marking_start.ticks(), compaction_start.ticks(), collection_exit.ticks()); gc_task_manager()->print_task_time_stamps(); } } bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, PSYoungGen* young_gen, PSOldGen* old_gen) { MutableSpace* const eden_space = young_gen->eden_space(); assert(!eden_space->is_empty(), "eden must be non-empty"); assert(young_gen->virtual_space()->alignment() == old_gen->virtual_space()->alignment(), "alignments do not match"); if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) { return false; } // Both generations must be completely committed. if (young_gen->virtual_space()->uncommitted_size() != 0) { return false; } if (old_gen->virtual_space()->uncommitted_size() != 0) { return false; } // Figure out how much to take from eden. Include the average amount promoted // in the total; otherwise the next young gen GC will simply bail out to a // full GC. const size_t alignment = old_gen->virtual_space()->alignment(); const size_t eden_used = eden_space->used_in_bytes(); const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average(); const size_t absorb_size = align_size_up(eden_used + promoted, alignment); const size_t eden_capacity = eden_space->capacity_in_bytes(); if (absorb_size >= eden_capacity) { return false; // Must leave some space in eden. } const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size; if (new_young_size < young_gen->min_gen_size()) { return false; // Respect young gen minimum size. } if (TraceAdaptiveGCBoundary && Verbose) { gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: " "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K " "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K " "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ", absorb_size / K, eden_capacity / K, (eden_capacity - absorb_size) / K, young_gen->from_space()->used_in_bytes() / K, young_gen->to_space()->used_in_bytes() / K, young_gen->capacity_in_bytes() / K, new_young_size / K); } // Fill the unused part of the old gen. MutableSpace* const old_space = old_gen->object_space(); MemRegion old_gen_unused(old_space->top(), old_space->end()); if (!old_gen_unused.is_empty()) { SharedHeap::fill_region_with_object(old_gen_unused); } // Take the live data from eden and set both top and end in the old gen to // eden top. (Need to set end because reset_after_change() mangles the region // from end to virtual_space->high() in debug builds). HeapWord* const new_top = eden_space->top(); old_gen->virtual_space()->expand_into(young_gen->virtual_space(), absorb_size); young_gen->reset_after_change(); old_space->set_top(new_top); old_space->set_end(new_top); old_gen->reset_after_change(); // Update the object start array for the filler object and the data from eden. ObjectStartArray* const start_array = old_gen->start_array(); HeapWord* const start = old_gen_unused.start(); for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) { start_array->allocate_block(addr); } // Could update the promoted average here, but it is not typically updated at // full GCs and the value to use is unclear. Something like // // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc. size_policy->set_bytes_absorbed_from_eden(absorb_size); return true; } GCTaskManager* const PSParallelCompact::gc_task_manager() { assert(ParallelScavengeHeap::gc_task_manager() != NULL, "shouldn't return NULL"); return ParallelScavengeHeap::gc_task_manager(); } void PSParallelCompact::marking_phase(ParCompactionManager* cm, bool maximum_heap_compaction) { // Recursively traverse all live objects and mark them EventMark m("1 mark object"); TraceTime tm("marking phase", print_phases(), true, gclog_or_tty); ParallelScavengeHeap* heap = gc_heap(); uint parallel_gc_threads = heap->gc_task_manager()->workers(); TaskQueueSetSuper* qset = ParCompactionManager::chunk_array(); ParallelTaskTerminator terminator(parallel_gc_threads, qset); PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm); PSParallelCompact::FollowStackClosure follow_stack_closure(cm); { TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty); GCTaskQueue* q = GCTaskQueue::create(); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe)); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles)); // We scan the thread roots in parallel Threads::create_thread_roots_marking_tasks(q); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer)); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler)); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management)); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary)); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti)); q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols)); if (parallel_gc_threads > 1) { for (uint j = 0; j < parallel_gc_threads; j++) { q->enqueue(new StealMarkingTask(&terminator)); } } WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create(); q->enqueue(fin); gc_task_manager()->add_list(q); fin->wait_for(); // We have to release the barrier tasks! WaitForBarrierGCTask::destroy(fin); } // Process reference objects found during marking { TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty); ReferencePolicy *soft_ref_policy; if (maximum_heap_compaction) { soft_ref_policy = new AlwaysClearPolicy(); } else { #ifdef COMPILER2 soft_ref_policy = new LRUMaxHeapPolicy(); #else soft_ref_policy = new LRUCurrentHeapPolicy(); #endif // COMPILER2 } assert(soft_ref_policy != NULL, "No soft reference policy"); if (ref_processor()->processing_is_mt()) { RefProcTaskExecutor task_executor; ref_processor()->process_discovered_references( soft_ref_policy, is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, &task_executor); } else { ref_processor()->process_discovered_references( soft_ref_policy, is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL); } } TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty); // Follow system dictionary roots and unload classes. bool purged_class = SystemDictionary::do_unloading(is_alive_closure()); // Follow code cache roots. CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure, purged_class); follow_stack(cm); // Flush marking stack. // Update subklass/sibling/implementor links of live klasses // revisit_klass_stack is used in follow_weak_klass_links(). follow_weak_klass_links(cm); // Visit symbol and interned string tables and delete unmarked oops SymbolTable::unlink(is_alive_closure()); StringTable::unlink(is_alive_closure()); assert(cm->marking_stack()->size() == 0, "stack should be empty by now"); assert(cm->overflow_stack()->is_empty(), "stack should be empty by now"); } // This should be moved to the shared markSweep code! class PSAlwaysTrueClosure: public BoolObjectClosure { public: void do_object(oop p) { ShouldNotReachHere(); } bool do_object_b(oop p) { return true; } }; static PSAlwaysTrueClosure always_true; void PSParallelCompact::adjust_roots() { // Adjust the pointers to reflect the new locations EventMark m("3 adjust roots"); TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty); // General strong roots. Universe::oops_do(adjust_root_pointer_closure()); ReferenceProcessor::oops_do(adjust_root_pointer_closure()); JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles Threads::oops_do(adjust_root_pointer_closure()); ObjectSynchronizer::oops_do(adjust_root_pointer_closure()); FlatProfiler::oops_do(adjust_root_pointer_closure()); Management::oops_do(adjust_root_pointer_closure()); JvmtiExport::oops_do(adjust_root_pointer_closure()); // SO_AllClasses SystemDictionary::oops_do(adjust_root_pointer_closure()); vmSymbols::oops_do(adjust_root_pointer_closure()); // Now adjust pointers in remaining weak roots. (All of which should // have been cleared if they pointed to non-surviving objects.) // Global (weak) JNI handles JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure()); CodeCache::oops_do(adjust_pointer_closure()); SymbolTable::oops_do(adjust_root_pointer_closure()); StringTable::oops_do(adjust_root_pointer_closure()); ref_processor()->weak_oops_do(adjust_root_pointer_closure()); // Roots were visited so references into the young gen in roots // may have been scanned. Process them also. // Should the reference processor have a span that excludes // young gen objects? PSScavenge::reference_processor()->weak_oops_do( adjust_root_pointer_closure()); } void PSParallelCompact::compact_perm(ParCompactionManager* cm) { EventMark m("4 compact perm"); TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty); // trace("4"); gc_heap()->perm_gen()->start_array()->reset(); move_and_update(cm, perm_space_id); } void PSParallelCompact::enqueue_chunk_draining_tasks(GCTaskQueue* q, uint parallel_gc_threads) { TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty); const unsigned int task_count = MAX2(parallel_gc_threads, 1U); for (unsigned int j = 0; j < task_count; j++) { q->enqueue(new DrainStacksCompactionTask()); } // Find all chunks that are available (can be filled immediately) and // distribute them to the thread stacks. The iteration is done in reverse // order (high to low) so the chunks will be removed in ascending order. const ParallelCompactData& sd = PSParallelCompact::summary_data(); size_t fillable_chunks = 0; // A count for diagnostic purposes. unsigned int which = 0; // The worker thread number. for (unsigned int id = to_space_id; id > perm_space_id; --id) { SpaceInfo* const space_info = _space_info + id; MutableSpace* const space = space_info->space(); HeapWord* const new_top = space_info->new_top(); const size_t beg_chunk = sd.addr_to_chunk_idx(space_info->dense_prefix()); const size_t end_chunk = sd.addr_to_chunk_idx(sd.chunk_align_up(new_top)); assert(end_chunk > 0, "perm gen cannot be empty"); for (size_t cur = end_chunk - 1; cur >= beg_chunk; --cur) { if (sd.chunk(cur)->claim_unsafe()) { ParCompactionManager* cm = ParCompactionManager::manager_array(which); cm->save_for_processing(cur); if (TraceParallelOldGCCompactionPhase && Verbose) { const size_t count_mod_8 = fillable_chunks & 7; if (count_mod_8 == 0) gclog_or_tty->print("fillable: "); gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur); if (count_mod_8 == 7) gclog_or_tty->cr(); } NOT_PRODUCT(++fillable_chunks;) // Assign chunks to threads in round-robin fashion. if (++which == task_count) { which = 0; } } } } if (TraceParallelOldGCCompactionPhase) { if (Verbose && (fillable_chunks & 7) != 0) gclog_or_tty->cr(); gclog_or_tty->print_cr("%u initially fillable chunks", fillable_chunks); } } #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q, uint parallel_gc_threads) { TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty); ParallelCompactData& sd = PSParallelCompact::summary_data(); // Iterate over all the spaces adding tasks for updating // chunks in the dense prefix. Assume that 1 gc thread // will work on opening the gaps and the remaining gc threads // will work on the dense prefix. SpaceId space_id = old_space_id; while (space_id != last_space_id) { HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix(); const MutableSpace* const space = _space_info[space_id].space(); if (dense_prefix_end == space->bottom()) { // There is no dense prefix for this space. space_id = next_compaction_space_id(space_id); continue; } // The dense prefix is before this chunk. size_t chunk_index_end_dense_prefix = sd.addr_to_chunk_idx(dense_prefix_end); ChunkData* const dense_prefix_cp = sd.chunk(chunk_index_end_dense_prefix); assert(dense_prefix_end == space->end() || dense_prefix_cp->available() || dense_prefix_cp->claimed(), "The chunk after the dense prefix should always be ready to fill"); size_t chunk_index_start = sd.addr_to_chunk_idx(space->bottom()); // Is there dense prefix work? size_t total_dense_prefix_chunks = chunk_index_end_dense_prefix - chunk_index_start; // How many chunks of the dense prefix should be given to // each thread? if (total_dense_prefix_chunks > 0) { uint tasks_for_dense_prefix = 1; if (UseParallelDensePrefixUpdate) { if (total_dense_prefix_chunks <= (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) { // Don't over partition. This assumes that // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value // so there are not many chunks to process. tasks_for_dense_prefix = parallel_gc_threads; } else { // Over partition tasks_for_dense_prefix = parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING; } } size_t chunks_per_thread = total_dense_prefix_chunks / tasks_for_dense_prefix; // Give each thread at least 1 chunk. if (chunks_per_thread == 0) { chunks_per_thread = 1; } for (uint k = 0; k < tasks_for_dense_prefix; k++) { if (chunk_index_start >= chunk_index_end_dense_prefix) { break; } // chunk_index_end is not processed size_t chunk_index_end = MIN2(chunk_index_start + chunks_per_thread, chunk_index_end_dense_prefix); q->enqueue(new UpdateDensePrefixTask( space_id, chunk_index_start, chunk_index_end)); chunk_index_start = chunk_index_end; } } // This gets any part of the dense prefix that did not // fit evenly. if (chunk_index_start < chunk_index_end_dense_prefix) { q->enqueue(new UpdateDensePrefixTask( space_id, chunk_index_start, chunk_index_end_dense_prefix)); } space_id = next_compaction_space_id(space_id); } // End tasks for dense prefix } void PSParallelCompact::enqueue_chunk_stealing_tasks( GCTaskQueue* q, ParallelTaskTerminator* terminator_ptr, uint parallel_gc_threads) { TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty); // Once a thread has drained it's stack, it should try to steal chunks from // other threads. if (parallel_gc_threads > 1) { for (uint j = 0; j < parallel_gc_threads; j++) { q->enqueue(new StealChunkCompactionTask(terminator_ptr)); } } } void PSParallelCompact::compact() { EventMark m("5 compact"); // trace("5"); TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty); ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); PSOldGen* old_gen = heap->old_gen(); old_gen->start_array()->reset(); uint parallel_gc_threads = heap->gc_task_manager()->workers(); TaskQueueSetSuper* qset = ParCompactionManager::chunk_array(); ParallelTaskTerminator terminator(parallel_gc_threads, qset); GCTaskQueue* q = GCTaskQueue::create(); enqueue_chunk_draining_tasks(q, parallel_gc_threads); enqueue_dense_prefix_tasks(q, parallel_gc_threads); enqueue_chunk_stealing_tasks(q, &terminator, parallel_gc_threads); { TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty); WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create(); q->enqueue(fin); gc_task_manager()->add_list(q); fin->wait_for(); // We have to release the barrier tasks! WaitForBarrierGCTask::destroy(fin); #ifdef ASSERT // Verify that all chunks have been processed before the deferred updates. // Note that perm_space_id is skipped; this type of verification is not // valid until the perm gen is compacted by chunks. for (unsigned int id = old_space_id; id < last_space_id; ++id) { verify_complete(SpaceId(id)); } #endif } { // Update the deferred objects, if any. Any compaction manager can be used. TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty); ParCompactionManager* cm = ParCompactionManager::manager_array(0); for (unsigned int id = old_space_id; id < last_space_id; ++id) { update_deferred_objects(cm, SpaceId(id)); } } } #ifdef ASSERT void PSParallelCompact::verify_complete(SpaceId space_id) { // All Chunks between space bottom() to new_top() should be marked as filled // and all Chunks between new_top() and top() should be available (i.e., // should have been emptied). ParallelCompactData& sd = summary_data(); SpaceInfo si = _space_info[space_id]; HeapWord* new_top_addr = sd.chunk_align_up(si.new_top()); HeapWord* old_top_addr = sd.chunk_align_up(si.space()->top()); const size_t beg_chunk = sd.addr_to_chunk_idx(si.space()->bottom()); const size_t new_top_chunk = sd.addr_to_chunk_idx(new_top_addr); const size_t old_top_chunk = sd.addr_to_chunk_idx(old_top_addr); bool issued_a_warning = false; size_t cur_chunk; for (cur_chunk = beg_chunk; cur_chunk < new_top_chunk; ++cur_chunk) { const ChunkData* const c = sd.chunk(cur_chunk); if (!c->completed()) { warning("chunk " SIZE_FORMAT " not filled: " "destination_count=" SIZE_FORMAT, cur_chunk, c->destination_count()); issued_a_warning = true; } } for (cur_chunk = new_top_chunk; cur_chunk < old_top_chunk; ++cur_chunk) { const ChunkData* const c = sd.chunk(cur_chunk); if (!c->available()) { warning("chunk " SIZE_FORMAT " not empty: " "destination_count=" SIZE_FORMAT, cur_chunk, c->destination_count()); issued_a_warning = true; } } if (issued_a_warning) { print_chunk_ranges(); } } #endif // #ifdef ASSERT void PSParallelCompact::compact_serial(ParCompactionManager* cm) { EventMark m("5 compact serial"); TraceTime tm("compact serial", print_phases(), true, gclog_or_tty); ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); PSYoungGen* young_gen = heap->young_gen(); PSOldGen* old_gen = heap->old_gen(); old_gen->start_array()->reset(); old_gen->move_and_update(cm); young_gen->move_and_update(cm); } void PSParallelCompact::follow_stack(ParCompactionManager* cm) { while(!cm->overflow_stack()->is_empty()) { oop obj = cm->overflow_stack()->pop(); obj->follow_contents(cm); } oop obj; // obj is a reference!!! while (cm->marking_stack()->pop_local(obj)) { // It would be nice to assert about the type of objects we might // pop, but they can come from anywhere, unfortunately. obj->follow_contents(cm); } } void PSParallelCompact::follow_weak_klass_links(ParCompactionManager* serial_cm) { // All klasses on the revisit stack are marked at this point. // Update and follow all subklass, sibling and implementor links. for (uint i = 0; i < ParallelGCThreads+1; i++) { ParCompactionManager* cm = ParCompactionManager::manager_array(i); KeepAliveClosure keep_alive_closure(cm); for (int i = 0; i < cm->revisit_klass_stack()->length(); i++) { cm->revisit_klass_stack()->at(i)->follow_weak_klass_links( is_alive_closure(), &keep_alive_closure); } follow_stack(cm); } } void PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) { cm->revisit_klass_stack()->push(k); } #ifdef VALIDATE_MARK_SWEEP void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) { if (!ValidateMarkSweep) return; if (!isroot) { if (_pointer_tracking) { guarantee(_adjusted_pointers->contains(p), "should have seen this pointer"); _adjusted_pointers->remove(p); } } else { ptrdiff_t index = _root_refs_stack->find(p); if (index != -1) { int l = _root_refs_stack->length(); if (l > 0 && l - 1 != index) { void* last = _root_refs_stack->pop(); assert(last != p, "should be different"); _root_refs_stack->at_put(index, last); } else { _root_refs_stack->remove(p); } } } } void PSParallelCompact::check_adjust_pointer(void* p) { _adjusted_pointers->push(p); } class AdjusterTracker: public OopClosure { public: AdjusterTracker() {}; void do_oop(oop* o) { PSParallelCompact::check_adjust_pointer(o); } void do_oop(narrowOop* o) { PSParallelCompact::check_adjust_pointer(o); } }; void PSParallelCompact::track_interior_pointers(oop obj) { if (ValidateMarkSweep) { _adjusted_pointers->clear(); _pointer_tracking = true; AdjusterTracker checker; obj->oop_iterate(&checker); } } void PSParallelCompact::check_interior_pointers() { if (ValidateMarkSweep) { _pointer_tracking = false; guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers"); } } void PSParallelCompact::reset_live_oop_tracking(bool at_perm) { if (ValidateMarkSweep) { guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops"); _live_oops_index = at_perm ? _live_oops_index_at_perm : 0; } } void PSParallelCompact::register_live_oop(oop p, size_t size) { if (ValidateMarkSweep) { _live_oops->push(p); _live_oops_size->push(size); _live_oops_index++; } } void PSParallelCompact::validate_live_oop(oop p, size_t size) { if (ValidateMarkSweep) { oop obj = _live_oops->at((int)_live_oops_index); guarantee(obj == p, "should be the same object"); guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size"); _live_oops_index++; } } void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top) { assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top), "should be moved to forwarded location"); if (ValidateMarkSweep) { PSParallelCompact::validate_live_oop(oop(q), size); _live_oops_moved_to->push(oop(compaction_top)); } if (RecordMarkSweepCompaction) { _cur_gc_live_oops->push(q); _cur_gc_live_oops_moved_to->push(compaction_top); _cur_gc_live_oops_size->push(size); } } void PSParallelCompact::compaction_complete() { if (RecordMarkSweepCompaction) { GrowableArray<HeapWord*>* _tmp_live_oops = _cur_gc_live_oops; GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to; GrowableArray<size_t> * _tmp_live_oops_size = _cur_gc_live_oops_size; _cur_gc_live_oops = _last_gc_live_oops; _cur_gc_live_oops_moved_to = _last_gc_live_oops_moved_to; _cur_gc_live_oops_size = _last_gc_live_oops_size; _last_gc_live_oops = _tmp_live_oops; _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to; _last_gc_live_oops_size = _tmp_live_oops_size; } } void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) { if (!RecordMarkSweepCompaction) { tty->print_cr("Requires RecordMarkSweepCompaction to be enabled"); return; } if (_last_gc_live_oops == NULL) { tty->print_cr("No compaction information gathered yet"); return; } for (int i = 0; i < _last_gc_live_oops->length(); i++) { HeapWord* old_oop = _last_gc_live_oops->at(i); size_t sz = _last_gc_live_oops_size->at(i); if (old_oop <= q && q < (old_oop + sz)) { HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i); size_t offset = (q - old_oop); tty->print_cr("Address " PTR_FORMAT, q); tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset); tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset); return; } } tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q); } #endif //VALIDATE_MARK_SWEEP // Update interior oops in the ranges of chunks [beg_chunk, end_chunk). void PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, SpaceId space_id, size_t beg_chunk, size_t end_chunk) { ParallelCompactData& sd = summary_data(); ParMarkBitMap* const mbm = mark_bitmap(); HeapWord* beg_addr = sd.chunk_to_addr(beg_chunk); HeapWord* const end_addr = sd.chunk_to_addr(end_chunk); assert(beg_chunk <= end_chunk, "bad chunk range"); assert(end_addr <= dense_prefix(space_id), "not in the dense prefix"); #ifdef ASSERT // Claim the chunks to avoid triggering an assert when they are marked as // filled. for (size_t claim_chunk = beg_chunk; claim_chunk < end_chunk; ++claim_chunk) { assert(sd.chunk(claim_chunk)->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 chunks. If a partial object crosses onto the chunk, skip it; it // will be marked for 'deferred update' when the object head is processed. // If dead space crosses onto the chunk, it is also skipped; it will be // filled when the prior chunk is processed. If neither of those apply, the // first word in the chunk is the start of a live object or dead space. assert(beg_addr > space(space_id)->bottom(), "sanity"); const ChunkData* const cp = sd.chunk(beg_chunk); if (cp->partial_obj_size() != 0) { beg_addr = sd.partial_obj_end(beg_chunk); } 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 Chunks. 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 chunks as filled. ChunkData* const beg_cp = sd.chunk(beg_chunk); ChunkData* const end_cp = sd.chunk(end_chunk); for (ChunkData* 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 = perm_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.chunk_align_up(space_info->new_top()); const ChunkData* const beg_chunk = sd.addr_to_chunk_ptr(beg_addr); const ChunkData* const end_chunk = sd.addr_to_chunk_ptr(end_addr); const ChunkData* cur_chunk; for (cur_chunk = beg_chunk; cur_chunk < end_chunk; ++cur_chunk) { HeapWord* const addr = cur_chunk->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, size_t src_chunk_idx) { ParMarkBitMap* const bitmap = mark_bitmap(); const ParallelCompactData& sd = summary_data(); const size_t ChunkSize = ParallelCompactData::ChunkSize; assert(sd.is_chunk_aligned(dest_addr), "not aligned"); const ChunkData* const src_chunk_ptr = sd.chunk(src_chunk_idx); const size_t partial_obj_size = src_chunk_ptr->partial_obj_size(); HeapWord* const src_chunk_destination = src_chunk_ptr->destination(); assert(dest_addr >= src_chunk_destination, "wrong src chunk"); assert(src_chunk_ptr->data_size() > 0, "src chunk cannot be empty"); HeapWord* const src_chunk_beg = sd.chunk_to_addr(src_chunk_idx); HeapWord* const src_chunk_end = src_chunk_beg + ChunkSize; HeapWord* addr = src_chunk_beg; if (dest_addr == src_chunk_destination) { // Return the first live word in the source chunk. if (partial_obj_size == 0) { addr = bitmap->find_obj_beg(addr, src_chunk_end); assert(addr < src_chunk_end, "no objects start in src chunk"); } return addr; } // Must skip some live data. size_t words_to_skip = dest_addr - src_chunk_destination; assert(src_chunk_ptr->data_size() > words_to_skip, "wrong src chunk"); 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_chunk_end); assert(addr < src_chunk_end, "wrong src chunk"); } 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 chunk. addr = skip_live_words(addr, src_chunk_end, words_to_skip); assert(addr < src_chunk_end, "wrong src chunk"); return addr; } void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm, size_t beg_chunk, HeapWord* end_addr) { ParallelCompactData& sd = summary_data(); ChunkData* const beg = sd.chunk(beg_chunk); HeapWord* const end_addr_aligned_up = sd.chunk_align_up(end_addr); ChunkData* const end = sd.addr_to_chunk_ptr(end_addr_aligned_up); size_t cur_idx = beg_chunk; for (ChunkData* cur = beg; cur < end; ++cur, ++cur_idx) { assert(cur->data_size() > 0, "chunk must have live data"); cur->decrement_destination_count(); if (cur_idx <= cur->source_chunk() && cur->available() && cur->claim()) { cm->save_for_processing(cur_idx); } } } size_t PSParallelCompact::next_src_chunk(MoveAndUpdateClosure& closure, SpaceId& src_space_id, HeapWord*& src_space_top, HeapWord* end_addr) { typedef ParallelCompactData::ChunkData ChunkData; ParallelCompactData& sd = PSParallelCompact::summary_data(); const size_t chunk_size = ParallelCompactData::ChunkSize; size_t src_chunk_idx = 0; // Skip empty chunks (if any) up to the top of the space. HeapWord* const src_aligned_up = sd.chunk_align_up(end_addr); ChunkData* src_chunk_ptr = sd.addr_to_chunk_ptr(src_aligned_up); HeapWord* const top_aligned_up = sd.chunk_align_up(src_space_top); const ChunkData* const top_chunk_ptr = sd.addr_to_chunk_ptr(top_aligned_up); while (src_chunk_ptr < top_chunk_ptr && src_chunk_ptr->data_size() == 0) { ++src_chunk_ptr; } if (src_chunk_ptr < top_chunk_ptr) { // The next source chunk is in the current space. Update src_chunk_idx and // the source address to match src_chunk_ptr. src_chunk_idx = sd.chunk(src_chunk_ptr); HeapWord* const src_chunk_addr = sd.chunk_to_addr(src_chunk_idx); if (src_chunk_addr > closure.source()) { closure.set_source(src_chunk_addr); } return src_chunk_idx; } // Switch to a new source space and find the first non-empty chunk. 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 ChunkData* const bottom_cp = sd.addr_to_chunk_ptr(bottom); // Iterate over the spaces that do not compact into themselves. if (bottom_cp->destination() != bottom) { HeapWord* const top_aligned_up = sd.chunk_align_up(space->top()); const ChunkData* const top_cp = sd.addr_to_chunk_ptr(top_aligned_up); for (const ChunkData* 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_chunk_idx = sd.chunk(src_cp); closure.set_source(sd.chunk_to_addr(src_chunk_idx)); return src_chunk_idx; } else { assert(src_cp->data_size() == 0, "sanity"); } } } } while (++space_id < last_space_id); assert(false, "no source chunk was found"); return 0; } void PSParallelCompact::fill_chunk(ParCompactionManager* cm, size_t chunk_idx) { typedef ParMarkBitMap::IterationStatus IterationStatus; const size_t ChunkSize = ParallelCompactData::ChunkSize; ParMarkBitMap* const bitmap = mark_bitmap(); ParallelCompactData& sd = summary_data(); ChunkData* const chunk_ptr = sd.chunk(chunk_idx); // Get the items needed to construct the closure. HeapWord* dest_addr = sd.chunk_to_addr(chunk_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), ChunkSize); // Get the source chunk and related info. size_t src_chunk_idx = chunk_ptr->source_chunk(); SpaceId src_space_id = space_id(sd.chunk_to_addr(src_chunk_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_chunk_idx)); // Adjust src_chunk_idx to prepare for decrementing destination counts (the // destination count is not decremented when a chunk is copied to itself). if (src_chunk_idx == chunk_idx) { src_chunk_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_chunk_idx, closure.source()); chunk_ptr->set_deferred_obj_addr(NULL); chunk_ptr->set_completed(); return; } HeapWord* const end_addr = sd.chunk_align_down(closure.source()); if (sd.chunk_align_down(old_src_addr) != end_addr) { // The partial object was copied from more than one source chunk. decrement_destination_counts(cm, src_chunk_idx, end_addr); // Move to the next source chunk, possibly switching spaces as well. All // args except end_addr may be modified. src_chunk_idx = next_src_chunk(closure, src_space_id, src_space_top, end_addr); } } do { HeapWord* const cur_addr = closure.source(); HeapWord* const end_addr = MIN2(sd.chunk_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 chunk does not end in the chunk. 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 chunk. chunk_ptr->set_deferred_obj_addr(closure.destination()); status = closure.copy_until_full(); // copies from closure.source() decrement_destination_counts(cm, src_chunk_idx, closure.source()); chunk_ptr->set_completed(); return; } if (status == ParMarkBitMap::full) { decrement_destination_counts(cm, src_chunk_idx, closure.source()); chunk_ptr->set_deferred_obj_addr(NULL); chunk_ptr->set_completed(); return; } decrement_destination_counts(cm, src_chunk_idx, end_addr); // Move to the next source chunk, possibly switching spaces as well. All // args except end_addr may be modified. src_chunk_idx = next_src_chunk(closure, src_space_id, src_space_top, end_addr); } while (true); } 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(); #ifdef ASSERT assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix"); if (cm->should_verify_only()) { VerifyUpdateClosure verify_update(cm, sp); bitmap->iterate(&verify_update, beg_addr, end_addr); return; } if (cm->should_reset_only()) { ResetObjectsClosure reset_objects(cm); bitmap->iterate(&reset_objects, beg_addr, end_addr); return; } #endif const size_t beg_chunk = sd.addr_to_chunk_idx(beg_addr); const size_t dp_chunk = sd.addr_to_chunk_idx(dp_addr); if (beg_chunk < dp_chunk) { update_and_deadwood_in_dense_prefix(cm, space_id, beg_chunk, dp_chunk); } // The destination of the first live object that starts in the chunk is one // past the end of the partial object entering the chunk (if any). HeapWord* const dest_addr = sd.partial_obj_end(dp_chunk); 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() { jlong ret_val = os::javaTimeMillis() - _time_of_last_gc; // XXX See note in genCollectedHeap::millis_since_last_gc(). if (ret_val < 0) { NOT_PRODUCT(warning("time warp: %d", ret_val);) return 0; } return ret_val; } void PSParallelCompact::reset_millis_since_last_gc() { _time_of_last_gc = os::javaTimeMillis(); } ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full() { if (source() != destination()) { assert(source() > destination(), "must copy to the left"); 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()) { assert(source() > destination(), "must copy to the left"); 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()) { assert(destination() < source(), "must copy to the left"); 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; } BitBlockUpdateClosure::BitBlockUpdateClosure(ParMarkBitMap* mbm, ParCompactionManager* cm, size_t chunk_index) : ParMarkBitMapClosure(mbm, cm), _live_data_left(0), _cur_block(0) { _chunk_start = PSParallelCompact::summary_data().chunk_to_addr(chunk_index); _chunk_end = PSParallelCompact::summary_data().chunk_to_addr(chunk_index) + ParallelCompactData::ChunkSize; _chunk_index = chunk_index; _cur_block = PSParallelCompact::summary_data().addr_to_block_idx(_chunk_start); } bool BitBlockUpdateClosure::chunk_contains_cur_block() { return ParallelCompactData::chunk_contains_block(_chunk_index, _cur_block); } void BitBlockUpdateClosure::reset_chunk(size_t chunk_index) { DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(7);) ParallelCompactData& sd = PSParallelCompact::summary_data(); _chunk_index = chunk_index; _live_data_left = 0; _chunk_start = sd.chunk_to_addr(chunk_index); _chunk_end = sd.chunk_to_addr(chunk_index) + ParallelCompactData::ChunkSize; // The first block in this chunk size_t first_block = sd.addr_to_block_idx(_chunk_start); size_t partial_live_size = sd.chunk(chunk_index)->partial_obj_size(); // Set the offset to 0. By definition it should have that value // but it may have been written while processing an earlier chunk. if (partial_live_size == 0) { // No live object extends onto the chunk. The first bit // in the bit map for the first chunk must be a start bit. // Although there may not be any marked bits, it is safe // to set it as a start bit. sd.block(first_block)->set_start_bit_offset(0); sd.block(first_block)->set_first_is_start_bit(true); } else if (sd.partial_obj_ends_in_block(first_block)) { sd.block(first_block)->set_end_bit_offset(0); sd.block(first_block)->set_first_is_start_bit(false); } else { // The partial object extends beyond the first block. // There is no object starting in the first block // so the offset and bit parity are not needed. // Set the the bit parity to start bit so assertions // work when not bit is found. sd.block(first_block)->set_end_bit_offset(0); sd.block(first_block)->set_first_is_start_bit(false); } _cur_block = first_block; #ifdef ASSERT if (sd.block(first_block)->first_is_start_bit()) { assert(!sd.partial_obj_ends_in_block(first_block), "Partial object cannot end in first block"); } if (PrintGCDetails && Verbose) { if (partial_live_size == 1) { gclog_or_tty->print_cr("first_block " PTR_FORMAT " _offset " PTR_FORMAT " _first_is_start_bit %d", first_block, sd.block(first_block)->raw_offset(), sd.block(first_block)->first_is_start_bit()); } } #endif DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(17);) } // This method is called when a object has been found (both beginning // and end of the object) in the range of iteration. This method is // calculating the words of live data to the left of a block. That live // data includes any object starting to the left of the block (i.e., // the live-data-to-the-left of block AAA will include the full size // of any object entering AAA). ParMarkBitMapClosure::IterationStatus BitBlockUpdateClosure::do_addr(HeapWord* addr, size_t words) { // add the size to the block data. HeapWord* obj = addr; ParallelCompactData& sd = PSParallelCompact::summary_data(); assert(bitmap()->obj_size(obj) == words, "bad size"); assert(_chunk_start <= obj, "object is not in chunk"); assert(obj + words <= _chunk_end, "object is not in chunk"); // Update the live data to the left size_t prev_live_data_left = _live_data_left; _live_data_left = _live_data_left + words; // Is this object in the current block. size_t block_of_obj = sd.addr_to_block_idx(obj); size_t block_of_obj_last = sd.addr_to_block_idx(obj + words - 1); HeapWord* block_of_obj_last_addr = sd.block_to_addr(block_of_obj_last); if (_cur_block < block_of_obj) { // // No object crossed the block boundary and this object was found // on the other side of the block boundary. Update the offset for // the new block with the data size that does not include this object. // // The first bit in block_of_obj is a start bit except in the // case where the partial object for the chunk extends into // this block. if (sd.partial_obj_ends_in_block(block_of_obj)) { sd.block(block_of_obj)->set_end_bit_offset(prev_live_data_left); } else { sd.block(block_of_obj)->set_start_bit_offset(prev_live_data_left); } // Does this object pass beyond the its block? if (block_of_obj < block_of_obj_last) { // Object crosses block boundary. Two blocks need to be udpated: // the current block where the object started // the block where the object ends // // The offset for blocks with no objects starting in them // (e.g., blocks between _cur_block and block_of_obj_last) // should not be needed. // Note that block_of_obj_last may be in another chunk. If so, // it should be overwritten later. This is a problem (writting // into a block in a later chunk) for parallel execution. assert(obj < block_of_obj_last_addr, "Object should start in previous block"); // obj is crossing into block_of_obj_last so the first bit // is and end bit. sd.block(block_of_obj_last)->set_end_bit_offset(_live_data_left); _cur_block = block_of_obj_last; } else { // _first_is_start_bit has already been set correctly // in the if-then-else above so don't reset it here. _cur_block = block_of_obj; } } else { // The current block only changes if the object extends beyound // the block it starts in. // // The object starts in the current block. // Does this object pass beyond the end of it? if (block_of_obj < block_of_obj_last) { // Object crosses block boundary. // See note above on possible blocks between block_of_obj and // block_of_obj_last assert(obj < block_of_obj_last_addr, "Object should start in previous block"); sd.block(block_of_obj_last)->set_end_bit_offset(_live_data_left); _cur_block = block_of_obj_last; } } // Return incomplete if there are more blocks to be done. if (chunk_contains_cur_block()) { return ParMarkBitMap::incomplete; } return ParMarkBitMap::complete; } // Verify the new location using the forwarding pointer // from MarkSweep::mark_sweep_phase2(). Set the mark_word // to the initial value. ParMarkBitMapClosure::IterationStatus PSParallelCompact::VerifyUpdateClosure::do_addr(HeapWord* addr, size_t words) { // The second arg (words) is not used. oop obj = (oop) addr; HeapWord* forwarding_ptr = (HeapWord*) obj->mark()->decode_pointer(); HeapWord* new_pointer = summary_data().calc_new_pointer(obj); if (forwarding_ptr == NULL) { // The object is dead or not moving. assert(bitmap()->is_unmarked(obj) || (new_pointer == (HeapWord*) obj), "Object liveness is wrong."); return ParMarkBitMap::incomplete; } assert(UseParallelOldGCDensePrefix || (HeapMaximumCompactionInterval > 1) || (MarkSweepAlwaysCompactCount > 1) || (forwarding_ptr == new_pointer), "Calculation of new location is incorrect"); return ParMarkBitMap::incomplete; } // Reset objects modified for debug checking. ParMarkBitMapClosure::IterationStatus PSParallelCompact::ResetObjectsClosure::do_addr(HeapWord* addr, size_t words) { // The second arg (words) is not used. oop obj = (oop) addr; obj->init_mark(); return ParMarkBitMap::incomplete; } // Prepare for compaction. This method is executed once // (i.e., by a single thread) before compaction. // Save the updated location of the intArrayKlassObj for // filling holes in the dense prefix. void PSParallelCompact::compact_prologue() { _updated_int_array_klass_obj = (klassOop) summary_data().calc_new_pointer(Universe::intArrayKlassObj()); } // The initial implementation of this method created a field // _next_compaction_space_id in SpaceInfo and initialized // that field in SpaceInfo::initialize_space_info(). That // required that _next_compaction_space_id be declared a // SpaceId in SpaceInfo and that would have required that // either SpaceId be declared in a separate class or that // it be declared in SpaceInfo. It didn't seem consistent // to declare it in SpaceInfo (didn't really fit logically). // Alternatively, defining a separate class to define SpaceId // seem excessive. This implementation is simple and localizes // the knowledge. PSParallelCompact::SpaceId PSParallelCompact::next_compaction_space_id(SpaceId id) { assert(id < last_space_id, "id out of range"); switch (id) { case perm_space_id : return last_space_id; case old_space_id : return eden_space_id; case eden_space_id : return from_space_id; case from_space_id : return to_space_id; case to_space_id : return last_space_id; default: assert(false, "Bad space id"); return last_space_id; } } // Here temporarily for debugging #ifdef ASSERT size_t ParallelCompactData::block_idx(BlockData* block) { size_t index = pointer_delta(block, PSParallelCompact::summary_data()._block_data, sizeof(BlockData)); return index; } #endif