--- old/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp 2015-05-12 11:55:55.242476044 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,1438 +0,0 @@ -/* - * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved. - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. - * - * This code is free software; you can redistribute it and/or modify it - * under the terms of the GNU General Public License version 2 only, as - * published by the Free Software Foundation. - * - * This code is distributed in the hope that it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License - * version 2 for more details (a copy is included in the LICENSE file that - * accompanied this code). - * - * You should have received a copy of the GNU General Public License version - * 2 along with this work; if not, write to the Free Software Foundation, - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. - * - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA - * or visit www.oracle.com if you need additional information or have any - * questions. - * - */ - -#ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP -#define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP - -#include "gc_implementation/parallelScavenge/objectStartArray.hpp" -#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" -#include "gc_implementation/parallelScavenge/parMarkBitMap.hpp" -#include "gc_implementation/shared/collectorCounters.hpp" -#include "gc_implementation/shared/mutableSpace.hpp" -#include "gc_interface/collectedHeap.hpp" -#include "oops/oop.hpp" - -class ParallelScavengeHeap; -class PSAdaptiveSizePolicy; -class PSYoungGen; -class PSOldGen; -class ParCompactionManager; -class ParallelTaskTerminator; -class PSParallelCompact; -class GCTaskManager; -class GCTaskQueue; -class PreGCValues; -class MoveAndUpdateClosure; -class RefProcTaskExecutor; -class ParallelOldTracer; -class STWGCTimer; - -// The SplitInfo class holds the information needed to 'split' a source region -// so that the live data can be copied to two destination *spaces*. Normally, -// all the live data in a region is copied to a single destination space (e.g., -// everything live in a region in eden is copied entirely into the old gen). -// However, when the heap is nearly full, all the live data in eden may not fit -// into the old gen. Copying only some of the regions from eden to old gen -// requires finding a region that does not contain a partial object (i.e., no -// live object crosses the region boundary) somewhere near the last object that -// does fit into the old gen. Since it's not always possible to find such a -// region, splitting is necessary for predictable behavior. -// -// A region is always split at the end of the partial object. This avoids -// additional tests when calculating the new location of a pointer, which is a -// very hot code path. The partial object and everything to its left will be -// copied to another space (call it dest_space_1). The live data to the right -// of the partial object will be copied either within the space itself, or to a -// different destination space (distinct from dest_space_1). -// -// Split points are identified during the summary phase, when region -// destinations are computed: data about the split, including the -// partial_object_size, is recorded in a SplitInfo record and the -// partial_object_size field in the summary data is set to zero. The zeroing is -// possible (and necessary) since the partial object will move to a different -// destination space than anything to its right, thus the partial object should -// not affect the locations of any objects to its right. -// -// The recorded data is used during the compaction phase, but only rarely: when -// the partial object on the split region will be copied across a destination -// region boundary. This test is made once each time a region is filled, and is -// a simple address comparison, so the overhead is negligible (see -// PSParallelCompact::first_src_addr()). -// -// Notes: -// -// Only regions with partial objects are split; a region without a partial -// object does not need any extra bookkeeping. -// -// At most one region is split per space, so the amount of data required is -// constant. -// -// A region is split only when the destination space would overflow. Once that -// happens, the destination space is abandoned and no other data (even from -// other source spaces) is targeted to that destination space. Abandoning the -// destination space may leave a somewhat large unused area at the end, if a -// large object caused the overflow. -// -// Future work: -// -// More bookkeeping would be required to continue to use the destination space. -// The most general solution would allow data from regions in two different -// source spaces to be "joined" in a single destination region. At the very -// least, additional code would be required in next_src_region() to detect the -// join and skip to an out-of-order source region. If the join region was also -// the last destination region to which a split region was copied (the most -// likely case), then additional work would be needed to get fill_region() to -// stop iteration and switch to a new source region at the right point. Basic -// idea would be to use a fake value for the top of the source space. It is -// doable, if a bit tricky. -// -// A simpler (but less general) solution would fill the remainder of the -// destination region with a dummy object and continue filling the next -// destination region. - -class SplitInfo -{ -public: - // Return true if this split info is valid (i.e., if a split has been - // recorded). The very first region cannot have a partial object and thus is - // never split, so 0 is the 'invalid' value. - bool is_valid() const { return _src_region_idx > 0; } - - // Return true if this split holds data for the specified source region. - inline bool is_split(size_t source_region) const; - - // The index of the split region, the size of the partial object on that - // region and the destination of the partial object. - size_t src_region_idx() const { return _src_region_idx; } - size_t partial_obj_size() const { return _partial_obj_size; } - HeapWord* destination() const { return _destination; } - - // The destination count of the partial object referenced by this split - // (either 1 or 2). This must be added to the destination count of the - // remainder of the source region. - unsigned int destination_count() const { return _destination_count; } - - // If a word within the partial object will be written to the first word of a - // destination region, this is the address of the destination region; - // otherwise this is NULL. - HeapWord* dest_region_addr() const { return _dest_region_addr; } - - // If a word within the partial object will be written to the first word of a - // destination region, this is the address of that word within the partial - // object; otherwise this is NULL. - HeapWord* first_src_addr() const { return _first_src_addr; } - - // Record the data necessary to split the region src_region_idx. - void record(size_t src_region_idx, size_t partial_obj_size, - HeapWord* destination); - - void clear(); - - DEBUG_ONLY(void verify_clear();) - -private: - size_t _src_region_idx; - size_t _partial_obj_size; - HeapWord* _destination; - unsigned int _destination_count; - HeapWord* _dest_region_addr; - HeapWord* _first_src_addr; -}; - -inline bool SplitInfo::is_split(size_t region_idx) const -{ - return _src_region_idx == region_idx && is_valid(); -} - -class SpaceInfo -{ - public: - MutableSpace* space() const { return _space; } - - // Where the free space will start after the collection. Valid only after the - // summary phase completes. - HeapWord* new_top() const { return _new_top; } - - // Allows new_top to be set. - HeapWord** new_top_addr() { return &_new_top; } - - // Where the smallest allowable dense prefix ends (used only for perm gen). - HeapWord* min_dense_prefix() const { return _min_dense_prefix; } - - // Where the dense prefix ends, or the compacted region begins. - HeapWord* dense_prefix() const { return _dense_prefix; } - - // The start array for the (generation containing the) space, or NULL if there - // is no start array. - ObjectStartArray* start_array() const { return _start_array; } - - SplitInfo& split_info() { return _split_info; } - - void set_space(MutableSpace* s) { _space = s; } - void set_new_top(HeapWord* addr) { _new_top = addr; } - void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; } - void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; } - void set_start_array(ObjectStartArray* s) { _start_array = s; } - - void publish_new_top() const { _space->set_top(_new_top); } - - private: - MutableSpace* _space; - HeapWord* _new_top; - HeapWord* _min_dense_prefix; - HeapWord* _dense_prefix; - ObjectStartArray* _start_array; - SplitInfo _split_info; -}; - -class ParallelCompactData -{ -public: - // Sizes are in HeapWords, unless indicated otherwise. - static const size_t Log2RegionSize; - static const size_t RegionSize; - static const size_t RegionSizeBytes; - - // Mask for the bits in a size_t to get an offset within a region. - static const size_t RegionSizeOffsetMask; - // Mask for the bits in a pointer to get an offset within a region. - static const size_t RegionAddrOffsetMask; - // Mask for the bits in a pointer to get the address of the start of a region. - static const size_t RegionAddrMask; - - static const size_t Log2BlockSize; - static const size_t BlockSize; - static const size_t BlockSizeBytes; - - static const size_t BlockSizeOffsetMask; - static const size_t BlockAddrOffsetMask; - static const size_t BlockAddrMask; - - static const size_t BlocksPerRegion; - static const size_t Log2BlocksPerRegion; - - class RegionData - { - public: - // Destination address of the region. - HeapWord* destination() const { return _destination; } - - // The first region containing data destined for this region. - size_t source_region() const { return _source_region; } - - // The object (if any) starting in this region and ending in a different - // region that could not be updated during the main (parallel) compaction - // phase. This is different from _partial_obj_addr, which is an object that - // extends onto a source region. However, the two uses do not overlap in - // time, so the same field is used to save space. - HeapWord* deferred_obj_addr() const { return _partial_obj_addr; } - - // The starting address of the partial object extending onto the region. - HeapWord* partial_obj_addr() const { return _partial_obj_addr; } - - // Size of the partial object extending onto the region (words). - size_t partial_obj_size() const { return _partial_obj_size; } - - // Size of live data that lies within this region due to objects that start - // in this region (words). This does not include the partial object - // extending onto the region (if any), or the part of an object that extends - // onto the next region (if any). - size_t live_obj_size() const { return _dc_and_los & los_mask; } - - // Total live data that lies within the region (words). - size_t data_size() const { return partial_obj_size() + live_obj_size(); } - - // The destination_count is the number of other regions to which data from - // this region will be copied. At the end of the summary phase, the valid - // values of destination_count are - // - // 0 - data from the region will be compacted completely into itself, or the - // region is empty. The region can be claimed and then filled. - // 1 - data from the region will be compacted into 1 other region; some - // data from the region may also be compacted into the region itself. - // 2 - data from the region will be copied to 2 other regions. - // - // During compaction as regions are emptied, the destination_count is - // decremented (atomically) and when it reaches 0, it can be claimed and - // then filled. - // - // A region is claimed for processing by atomically changing the - // destination_count to the claimed value (dc_claimed). After a region has - // been filled, the destination_count should be set to the completed value - // (dc_completed). - inline uint destination_count() const; - inline uint destination_count_raw() const; - - // Whether the block table for this region has been filled. - inline bool blocks_filled() const; - - // Number of times the block table was filled. - DEBUG_ONLY(inline size_t blocks_filled_count() const;) - - // The location of the java heap data that corresponds to this region. - inline HeapWord* data_location() const; - - // The highest address referenced by objects in this region. - inline HeapWord* highest_ref() const; - - // Whether this region is available to be claimed, has been claimed, or has - // been completed. - // - // Minor subtlety: claimed() returns true if the region is marked - // completed(), which is desirable since a region must be claimed before it - // can be completed. - bool available() const { return _dc_and_los < dc_one; } - bool claimed() const { return _dc_and_los >= dc_claimed; } - bool completed() const { return _dc_and_los >= dc_completed; } - - // These are not atomic. - void set_destination(HeapWord* addr) { _destination = addr; } - void set_source_region(size_t region) { _source_region = region; } - void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } - void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } - void set_partial_obj_size(size_t words) { - _partial_obj_size = (region_sz_t) words; - } - inline void set_blocks_filled(); - - inline void set_destination_count(uint count); - inline void set_live_obj_size(size_t words); - inline void set_data_location(HeapWord* addr); - inline void set_completed(); - inline bool claim_unsafe(); - - // These are atomic. - inline void add_live_obj(size_t words); - inline void set_highest_ref(HeapWord* addr); - inline void decrement_destination_count(); - inline bool claim(); - - private: - // The type used to represent object sizes within a region. - typedef uint region_sz_t; - - // Constants for manipulating the _dc_and_los field, which holds both the - // destination count and live obj size. The live obj size lives at the - // least significant end so no masking is necessary when adding. - static const region_sz_t dc_shift; // Shift amount. - static const region_sz_t dc_mask; // Mask for destination count. - static const region_sz_t dc_one; // 1, shifted appropriately. - static const region_sz_t dc_claimed; // Region has been claimed. - static const region_sz_t dc_completed; // Region has been completed. - static const region_sz_t los_mask; // Mask for live obj size. - - HeapWord* _destination; - size_t _source_region; - HeapWord* _partial_obj_addr; - region_sz_t _partial_obj_size; - region_sz_t volatile _dc_and_los; - bool _blocks_filled; - -#ifdef ASSERT - size_t _blocks_filled_count; // Number of block table fills. - - // These enable optimizations that are only partially implemented. Use - // debug builds to prevent the code fragments from breaking. - HeapWord* _data_location; - HeapWord* _highest_ref; -#endif // #ifdef ASSERT - -#ifdef ASSERT - public: - uint _pushed; // 0 until region is pushed onto a stack - private: -#endif - }; - - // "Blocks" allow shorter sections of the bitmap to be searched. Each Block - // holds an offset, which is the amount of live data in the Region to the left - // of the first live object that starts in the Block. - class BlockData - { - public: - typedef unsigned short int blk_ofs_t; - - blk_ofs_t offset() const { return _offset; } - void set_offset(size_t val) { _offset = (blk_ofs_t)val; } - - private: - blk_ofs_t _offset; - }; - -public: - ParallelCompactData(); - bool initialize(MemRegion covered_region); - - size_t region_count() const { return _region_count; } - size_t reserved_byte_size() const { return _reserved_byte_size; } - - // Convert region indices to/from RegionData pointers. - inline RegionData* region(size_t region_idx) const; - inline size_t region(const RegionData* const region_ptr) const; - - size_t block_count() const { return _block_count; } - inline BlockData* block(size_t block_idx) const; - inline size_t block(const BlockData* block_ptr) const; - - void add_obj(HeapWord* addr, size_t len); - void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); } - - // Fill in the regions covering [beg, end) so that no data moves; i.e., the - // destination of region n is simply the start of region n. The argument beg - // must be region-aligned; end need not be. - void summarize_dense_prefix(HeapWord* beg, HeapWord* end); - - HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info, - HeapWord* destination, HeapWord* target_end, - HeapWord** target_next); - bool summarize(SplitInfo& split_info, - HeapWord* source_beg, HeapWord* source_end, - HeapWord** source_next, - HeapWord* target_beg, HeapWord* target_end, - HeapWord** target_next); - - void clear(); - void clear_range(size_t beg_region, size_t end_region); - void clear_range(HeapWord* beg, HeapWord* end) { - clear_range(addr_to_region_idx(beg), addr_to_region_idx(end)); - } - - // Return the number of words between addr and the start of the region - // containing addr. - inline size_t region_offset(const HeapWord* addr) const; - - // Convert addresses to/from a region index or region pointer. - inline size_t addr_to_region_idx(const HeapWord* addr) const; - inline RegionData* addr_to_region_ptr(const HeapWord* addr) const; - inline HeapWord* region_to_addr(size_t region) const; - inline HeapWord* region_to_addr(size_t region, size_t offset) const; - inline HeapWord* region_to_addr(const RegionData* region) const; - - inline HeapWord* region_align_down(HeapWord* addr) const; - inline HeapWord* region_align_up(HeapWord* addr) const; - inline bool is_region_aligned(HeapWord* addr) const; - - // Analogous to region_offset() for blocks. - size_t block_offset(const HeapWord* addr) const; - size_t addr_to_block_idx(const HeapWord* addr) const; - size_t addr_to_block_idx(const oop obj) const { - return addr_to_block_idx((HeapWord*) obj); - } - inline BlockData* addr_to_block_ptr(const HeapWord* addr) const; - inline HeapWord* block_to_addr(size_t block) const; - inline size_t region_to_block_idx(size_t region) const; - - inline HeapWord* block_align_down(HeapWord* addr) const; - inline HeapWord* block_align_up(HeapWord* addr) const; - inline bool is_block_aligned(HeapWord* addr) const; - - // Return the address one past the end of the partial object. - HeapWord* partial_obj_end(size_t region_idx) const; - - // Return the location of the object after compaction. - HeapWord* calc_new_pointer(HeapWord* addr); - - HeapWord* calc_new_pointer(oop p) { - return calc_new_pointer((HeapWord*) p); - } - -#ifdef ASSERT - void verify_clear(const PSVirtualSpace* vspace); - void verify_clear(); -#endif // #ifdef ASSERT - -private: - bool initialize_block_data(); - bool initialize_region_data(size_t region_size); - PSVirtualSpace* create_vspace(size_t count, size_t element_size); - -private: - HeapWord* _region_start; -#ifdef ASSERT - HeapWord* _region_end; -#endif // #ifdef ASSERT - - PSVirtualSpace* _region_vspace; - size_t _reserved_byte_size; - RegionData* _region_data; - size_t _region_count; - - PSVirtualSpace* _block_vspace; - BlockData* _block_data; - size_t _block_count; -}; - -inline uint -ParallelCompactData::RegionData::destination_count_raw() const -{ - return _dc_and_los & dc_mask; -} - -inline uint -ParallelCompactData::RegionData::destination_count() const -{ - return destination_count_raw() >> dc_shift; -} - -inline bool -ParallelCompactData::RegionData::blocks_filled() const -{ - return _blocks_filled; -} - -#ifdef ASSERT -inline size_t -ParallelCompactData::RegionData::blocks_filled_count() const -{ - return _blocks_filled_count; -} -#endif // #ifdef ASSERT - -inline void -ParallelCompactData::RegionData::set_blocks_filled() -{ - _blocks_filled = true; - // Debug builds count the number of times the table was filled. - DEBUG_ONLY(Atomic::inc_ptr(&_blocks_filled_count)); -} - -inline void -ParallelCompactData::RegionData::set_destination_count(uint count) -{ - assert(count <= (dc_completed >> dc_shift), "count too large"); - const region_sz_t live_sz = (region_sz_t) live_obj_size(); - _dc_and_los = (count << dc_shift) | live_sz; -} - -inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words) -{ - assert(words <= los_mask, "would overflow"); - _dc_and_los = destination_count_raw() | (region_sz_t)words; -} - -inline void ParallelCompactData::RegionData::decrement_destination_count() -{ - assert(_dc_and_los < dc_claimed, "already claimed"); - assert(_dc_and_los >= dc_one, "count would go negative"); - Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los); -} - -inline HeapWord* ParallelCompactData::RegionData::data_location() const -{ - DEBUG_ONLY(return _data_location;) - NOT_DEBUG(return NULL;) -} - -inline HeapWord* ParallelCompactData::RegionData::highest_ref() const -{ - DEBUG_ONLY(return _highest_ref;) - NOT_DEBUG(return NULL;) -} - -inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr) -{ - DEBUG_ONLY(_data_location = addr;) -} - -inline void ParallelCompactData::RegionData::set_completed() -{ - assert(claimed(), "must be claimed first"); - _dc_and_los = dc_completed | (region_sz_t) live_obj_size(); -} - -// MT-unsafe claiming of a region. Should only be used during single threaded -// execution. -inline bool ParallelCompactData::RegionData::claim_unsafe() -{ - if (available()) { - _dc_and_los |= dc_claimed; - return true; - } - return false; -} - -inline void ParallelCompactData::RegionData::add_live_obj(size_t words) -{ - assert(words <= (size_t)los_mask - live_obj_size(), "overflow"); - Atomic::add((int) words, (volatile int*) &_dc_and_los); -} - -inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr) -{ -#ifdef ASSERT - HeapWord* tmp = _highest_ref; - while (addr > tmp) { - tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp); - } -#endif // #ifdef ASSERT -} - -inline bool ParallelCompactData::RegionData::claim() -{ - const int los = (int) live_obj_size(); - const int old = Atomic::cmpxchg(dc_claimed | los, - (volatile int*) &_dc_and_los, los); - return old == los; -} - -inline ParallelCompactData::RegionData* -ParallelCompactData::region(size_t region_idx) const -{ - assert(region_idx <= region_count(), "bad arg"); - return _region_data + region_idx; -} - -inline size_t -ParallelCompactData::region(const RegionData* const region_ptr) const -{ - assert(region_ptr >= _region_data, "bad arg"); - assert(region_ptr <= _region_data + region_count(), "bad arg"); - return pointer_delta(region_ptr, _region_data, sizeof(RegionData)); -} - -inline ParallelCompactData::BlockData* -ParallelCompactData::block(size_t n) const { - assert(n < block_count(), "bad arg"); - return _block_data + n; -} - -inline size_t -ParallelCompactData::region_offset(const HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr <= _region_end, "bad addr"); - return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize; -} - -inline size_t -ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr <= _region_end, "bad addr"); - return pointer_delta(addr, _region_start) >> Log2RegionSize; -} - -inline ParallelCompactData::RegionData* -ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const -{ - return region(addr_to_region_idx(addr)); -} - -inline HeapWord* -ParallelCompactData::region_to_addr(size_t region) const -{ - assert(region <= _region_count, "region out of range"); - return _region_start + (region << Log2RegionSize); -} - -inline HeapWord* -ParallelCompactData::region_to_addr(const RegionData* region) const -{ - return region_to_addr(pointer_delta(region, _region_data, - sizeof(RegionData))); -} - -inline HeapWord* -ParallelCompactData::region_to_addr(size_t region, size_t offset) const -{ - assert(region <= _region_count, "region out of range"); - assert(offset < RegionSize, "offset too big"); // This may be too strict. - return region_to_addr(region) + offset; -} - -inline HeapWord* -ParallelCompactData::region_align_down(HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr < _region_end + RegionSize, "bad addr"); - return (HeapWord*)(size_t(addr) & RegionAddrMask); -} - -inline HeapWord* -ParallelCompactData::region_align_up(HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr <= _region_end, "bad addr"); - return region_align_down(addr + RegionSizeOffsetMask); -} - -inline bool -ParallelCompactData::is_region_aligned(HeapWord* addr) const -{ - return region_offset(addr) == 0; -} - -inline size_t -ParallelCompactData::block_offset(const HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr <= _region_end, "bad addr"); - return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize; -} - -inline size_t -ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr <= _region_end, "bad addr"); - return pointer_delta(addr, _region_start) >> Log2BlockSize; -} - -inline ParallelCompactData::BlockData* -ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const -{ - return block(addr_to_block_idx(addr)); -} - -inline HeapWord* -ParallelCompactData::block_to_addr(size_t block) const -{ - assert(block < _block_count, "block out of range"); - return _region_start + (block << Log2BlockSize); -} - -inline size_t -ParallelCompactData::region_to_block_idx(size_t region) const -{ - return region << Log2BlocksPerRegion; -} - -inline HeapWord* -ParallelCompactData::block_align_down(HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr < _region_end + RegionSize, "bad addr"); - return (HeapWord*)(size_t(addr) & BlockAddrMask); -} - -inline HeapWord* -ParallelCompactData::block_align_up(HeapWord* addr) const -{ - assert(addr >= _region_start, "bad addr"); - assert(addr <= _region_end, "bad addr"); - return block_align_down(addr + BlockSizeOffsetMask); -} - -inline bool -ParallelCompactData::is_block_aligned(HeapWord* addr) const -{ - return block_offset(addr) == 0; -} - -// Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the -// do_addr() method. -// -// The closure is initialized with the number of heap words to process -// (words_remaining()), and becomes 'full' when it reaches 0. The do_addr() -// methods in subclasses should update the total as words are processed. Since -// only one subclass actually uses this mechanism to terminate iteration, the -// default initial value is > 0. The implementation is here and not in the -// single subclass that uses it to avoid making is_full() virtual, and thus -// adding a virtual call per live object. - -class ParMarkBitMapClosure: public StackObj { - public: - typedef ParMarkBitMap::idx_t idx_t; - typedef ParMarkBitMap::IterationStatus IterationStatus; - - public: - inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm, - size_t words = max_uintx); - - inline ParCompactionManager* compaction_manager() const; - inline ParMarkBitMap* bitmap() const; - inline size_t words_remaining() const; - inline bool is_full() const; - inline HeapWord* source() const; - - inline void set_source(HeapWord* addr); - - virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0; - - protected: - inline void decrement_words_remaining(size_t words); - - private: - ParMarkBitMap* const _bitmap; - ParCompactionManager* const _compaction_manager; - DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger. - size_t _words_remaining; // Words left to copy. - - protected: - HeapWord* _source; // Next addr that would be read. -}; - -inline -ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap, - ParCompactionManager* cm, - size_t words): - _bitmap(bitmap), _compaction_manager(cm) -#ifdef ASSERT - , _initial_words_remaining(words) -#endif -{ - _words_remaining = words; - _source = NULL; -} - -inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const { - return _compaction_manager; -} - -inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const { - return _bitmap; -} - -inline size_t ParMarkBitMapClosure::words_remaining() const { - return _words_remaining; -} - -inline bool ParMarkBitMapClosure::is_full() const { - return words_remaining() == 0; -} - -inline HeapWord* ParMarkBitMapClosure::source() const { - return _source; -} - -inline void ParMarkBitMapClosure::set_source(HeapWord* addr) { - _source = addr; -} - -inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) { - assert(_words_remaining >= words, "processed too many words"); - _words_remaining -= words; -} - -// The UseParallelOldGC collector is a stop-the-world garbage collector that -// does parts of the collection using parallel threads. The collection includes -// the tenured generation and the young generation. The permanent generation is -// collected at the same time as the other two generations but the permanent -// generation is collect by a single GC thread. The permanent generation is -// collected serially because of the requirement that during the processing of a -// klass AAA, any objects reference by AAA must already have been processed. -// This requirement is enforced by a left (lower address) to right (higher -// address) sliding compaction. -// -// There are four phases of the collection. -// -// - marking phase -// - summary phase -// - compacting phase -// - clean up phase -// -// Roughly speaking these phases correspond, respectively, to -// - mark all the live objects -// - calculate the destination of each object at the end of the collection -// - move the objects to their destination -// - update some references and reinitialize some variables -// -// These three phases are invoked in PSParallelCompact::invoke_no_policy(). The -// marking phase is implemented in PSParallelCompact::marking_phase() and does a -// complete marking of the heap. The summary phase is implemented in -// PSParallelCompact::summary_phase(). The move and update phase is implemented -// in PSParallelCompact::compact(). -// -// A space that is being collected is divided into regions and with each region -// is associated an object of type ParallelCompactData. Each region is of a -// fixed size and typically will contain more than 1 object and may have parts -// of objects at the front and back of the region. -// -// region -----+---------------------+---------- -// objects covered [ AAA )[ BBB )[ CCC )[ DDD ) -// -// The marking phase does a complete marking of all live objects in the heap. -// The marking also compiles the size of the data for all live objects covered -// by the region. This size includes the part of any live object spanning onto -// the region (part of AAA if it is live) from the front, all live objects -// contained in the region (BBB and/or CCC if they are live), and the part of -// any live objects covered by the region that extends off the region (part of -// DDD if it is live). The marking phase uses multiple GC threads and marking -// is done in a bit array of type ParMarkBitMap. The marking of the bit map is -// done atomically as is the accumulation of the size of the live objects -// covered by a region. -// -// The summary phase calculates the total live data to the left of each region -// XXX. Based on that total and the bottom of the space, it can calculate the -// starting location of the live data in XXX. The summary phase calculates for -// each region XXX quantities such as -// -// - the amount of live data at the beginning of a region from an object -// entering the region. -// - the location of the first live data on the region -// - a count of the number of regions receiving live data from XXX. -// -// See ParallelCompactData for precise details. The summary phase also -// calculates the dense prefix for the compaction. The dense prefix is a -// portion at the beginning of the space that is not moved. The objects in the -// dense prefix do need to have their object references updated. See method -// summarize_dense_prefix(). -// -// The summary phase is done using 1 GC thread. -// -// The compaction phase moves objects to their new location and updates all -// references in the object. -// -// A current exception is that objects that cross a region boundary are moved -// but do not have their references updated. References are not updated because -// it cannot easily be determined if the klass pointer KKK for the object AAA -// has been updated. KKK likely resides in a region to the left of the region -// containing AAA. These AAA's have there references updated at the end in a -// clean up phase. See the method PSParallelCompact::update_deferred_objects(). -// An alternate strategy is being investigated for this deferral of updating. -// -// Compaction is done on a region basis. A region that is ready to be filled is -// put on a ready list and GC threads take region off the list and fill them. A -// region is ready to be filled if it empty of live objects. Such a region may -// have been initially empty (only contained dead objects) or may have had all -// its live objects copied out already. A region that compacts into itself is -// also ready for filling. The ready list is initially filled with empty -// regions and regions compacting into themselves. There is always at least 1 -// region that can be put on the ready list. The regions are atomically added -// and removed from the ready list. - -class PSParallelCompact : AllStatic { - public: - // Convenient access to type names. - typedef ParMarkBitMap::idx_t idx_t; - typedef ParallelCompactData::RegionData RegionData; - typedef ParallelCompactData::BlockData BlockData; - - typedef enum { - old_space_id, eden_space_id, - from_space_id, to_space_id, last_space_id - } SpaceId; - - public: - // Inline closure decls - // - class IsAliveClosure: public BoolObjectClosure { - public: - virtual bool do_object_b(oop p); - }; - - class AdjustPointerClosure: public ExtendedOopClosure { - public: - template void do_oop_nv(T* p); - virtual void do_oop(oop* p); - virtual void do_oop(narrowOop* p); - - // This closure provides its own oop verification code. - debug_only(virtual bool should_verify_oops() { return false; }) - }; - - class AdjustKlassClosure : public KlassClosure { - public: - void do_klass(Klass* klass); - }; - - friend class AdjustPointerClosure; - friend class AdjustKlassClosure; - friend class RefProcTaskProxy; - - private: - static STWGCTimer _gc_timer; - static ParallelOldTracer _gc_tracer; - static elapsedTimer _accumulated_time; - static unsigned int _total_invocations; - static unsigned int _maximum_compaction_gc_num; - static jlong _time_of_last_gc; // ms - static CollectorCounters* _counters; - static ParMarkBitMap _mark_bitmap; - static ParallelCompactData _summary_data; - static IsAliveClosure _is_alive_closure; - static SpaceInfo _space_info[last_space_id]; - static bool _print_phases; - static AdjustPointerClosure _adjust_pointer_closure; - static AdjustKlassClosure _adjust_klass_closure; - - // Reference processing (used in ...follow_contents) - static ReferenceProcessor* _ref_processor; - - // Values computed at initialization and used by dead_wood_limiter(). - static double _dwl_mean; - static double _dwl_std_dev; - static double _dwl_first_term; - static double _dwl_adjustment; -#ifdef ASSERT - static bool _dwl_initialized; -#endif // #ifdef ASSERT - - - public: - static ParallelOldTracer* gc_tracer() { return &_gc_tracer; } - - private: - - static void initialize_space_info(); - - // Return true if details about individual phases should be printed. - static inline bool print_phases(); - - // Clear the marking bitmap and summary data that cover the specified space. - static void clear_data_covering_space(SpaceId id); - - static void pre_compact(PreGCValues* pre_gc_values); - static void post_compact(); - - // Mark live objects - static void marking_phase(ParCompactionManager* cm, - bool maximum_heap_compaction, - ParallelOldTracer *gc_tracer); - - // Compute the dense prefix for the designated space. This is an experimental - // implementation currently not used in production. - static HeapWord* compute_dense_prefix_via_density(const SpaceId id, - bool maximum_compaction); - - // Methods used to compute the dense prefix. - - // Compute the value of the normal distribution at x = density. The mean and - // standard deviation are values saved by initialize_dead_wood_limiter(). - static inline double normal_distribution(double density); - - // Initialize the static vars used by dead_wood_limiter(). - static void initialize_dead_wood_limiter(); - - // Return the percentage of space that can be treated as "dead wood" (i.e., - // not reclaimed). - static double dead_wood_limiter(double density, size_t min_percent); - - // Find the first (left-most) region in the range [beg, end) that has at least - // dead_words of dead space to the left. The argument beg must be the first - // region in the space that is not completely live. - static RegionData* dead_wood_limit_region(const RegionData* beg, - const RegionData* end, - size_t dead_words); - - // Return a pointer to the first region in the range [beg, end) that is not - // completely full. - static RegionData* first_dead_space_region(const RegionData* beg, - const RegionData* end); - - // Return a value indicating the benefit or 'yield' if the compacted region - // were to start (or equivalently if the dense prefix were to end) at the - // candidate region. Higher values are better. - // - // The value is based on the amount of space reclaimed vs. the costs of (a) - // updating references in the dense prefix plus (b) copying objects and - // updating references in the compacted region. - static inline double reclaimed_ratio(const RegionData* const candidate, - HeapWord* const bottom, - HeapWord* const top, - HeapWord* const new_top); - - // Compute the dense prefix for the designated space. - static HeapWord* compute_dense_prefix(const SpaceId id, - bool maximum_compaction); - - // Return true if dead space crosses onto the specified Region; bit must be - // the bit index corresponding to the first word of the Region. - static inline bool dead_space_crosses_boundary(const RegionData* region, - idx_t bit); - - // Summary phase utility routine to fill dead space (if any) at the dense - // prefix boundary. Should only be called if the the dense prefix is - // non-empty. - static void fill_dense_prefix_end(SpaceId id); - - // Clear the summary data source_region field for the specified addresses. - static void clear_source_region(HeapWord* beg_addr, HeapWord* end_addr); - -#ifndef PRODUCT - // Routines to provoke splitting a young gen space (ParallelOldGCSplitALot). - - // Fill the region [start, start + words) with live object(s). Only usable - // for the old and permanent generations. - static void fill_with_live_objects(SpaceId id, HeapWord* const start, - size_t words); - // Include the new objects in the summary data. - static void summarize_new_objects(SpaceId id, HeapWord* start); - - // Add live objects to a survivor space since it's rare that both survivors - // are non-empty. - static void provoke_split_fill_survivor(SpaceId id); - - // Add live objects and/or choose the dense prefix to provoke splitting. - static void provoke_split(bool & maximum_compaction); -#endif - - static void summarize_spaces_quick(); - static void summarize_space(SpaceId id, bool maximum_compaction); - static void summary_phase(ParCompactionManager* cm, bool maximum_compaction); - - // Adjust addresses in roots. Does not adjust addresses in heap. - static void adjust_roots(); - - DEBUG_ONLY(static void write_block_fill_histogram(outputStream* const out);) - - // Move objects to new locations. - static void compact_perm(ParCompactionManager* cm); - static void compact(); - - // Add available regions to the stack and draining tasks to the task queue. - static void enqueue_region_draining_tasks(GCTaskQueue* q, - uint parallel_gc_threads); - - // Add dense prefix update tasks to the task queue. - static void enqueue_dense_prefix_tasks(GCTaskQueue* q, - uint parallel_gc_threads); - - // Add region stealing tasks to the task queue. - static void enqueue_region_stealing_tasks( - GCTaskQueue* q, - ParallelTaskTerminator* terminator_ptr, - uint parallel_gc_threads); - - // If objects are left in eden after a collection, try to move the boundary - // and absorb them into the old gen. Returns true if eden was emptied. - static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, - PSYoungGen* young_gen, - PSOldGen* old_gen); - - // Reset time since last full gc - static void reset_millis_since_last_gc(); - - public: - - PSParallelCompact(); - - static void invoke(bool maximum_heap_compaction); - static bool invoke_no_policy(bool maximum_heap_compaction); - - static void post_initialize(); - // Perform initialization for PSParallelCompact that requires - // allocations. This should be called during the VM initialization - // at a pointer where it would be appropriate to return a JNI_ENOMEM - // in the event of a failure. - static bool initialize(); - - // Closure accessors - static PSParallelCompact::AdjustPointerClosure* adjust_pointer_closure() { - return &_adjust_pointer_closure; - } - static KlassClosure* adjust_klass_closure() { return (KlassClosure*)&_adjust_klass_closure; } - static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; } - - // Public accessors - static elapsedTimer* accumulated_time() { return &_accumulated_time; } - static unsigned int total_invocations() { return _total_invocations; } - static CollectorCounters* counters() { return _counters; } - - // Used to add tasks - static GCTaskManager* const gc_task_manager(); - - // Marking support - static inline bool mark_obj(oop obj); - static inline bool is_marked(oop obj); - - template static inline void adjust_pointer(T* p); - - // Compaction support. - // Return true if p is in the range [beg_addr, end_addr). - static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr); - static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr); - - // Convenience wrappers for per-space data kept in _space_info. - static inline MutableSpace* space(SpaceId space_id); - static inline HeapWord* new_top(SpaceId space_id); - static inline HeapWord* dense_prefix(SpaceId space_id); - static inline ObjectStartArray* start_array(SpaceId space_id); - - // Move and update the live objects in the specified space. - static void move_and_update(ParCompactionManager* cm, SpaceId space_id); - - // Process the end of the given region range in the dense prefix. - // This includes saving any object not updated. - static void dense_prefix_regions_epilogue(ParCompactionManager* cm, - size_t region_start_index, - size_t region_end_index, - idx_t exiting_object_offset, - idx_t region_offset_start, - idx_t region_offset_end); - - // Update a region in the dense prefix. For each live object - // in the region, update it's interior references. For each - // dead object, fill it with deadwood. Dead space at the end - // of a region range will be filled to the start of the next - // live object regardless of the region_index_end. None of the - // objects in the dense prefix move and dead space is dead - // (holds only dead objects that don't need any processing), so - // dead space can be filled in any order. - static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, - SpaceId space_id, - size_t region_index_start, - size_t region_index_end); - - // Return the address of the count + 1st live word in the range [beg, end). - static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count); - - // Return the address of the word to be copied to dest_addr, which must be - // aligned to a region boundary. - static HeapWord* first_src_addr(HeapWord* const dest_addr, - SpaceId src_space_id, - size_t src_region_idx); - - // Determine the next source region, set closure.source() to the start of the - // new region return the region index. Parameter end_addr is the address one - // beyond the end of source range just processed. If necessary, switch to a - // new source space and set src_space_id (in-out parameter) and src_space_top - // (out parameter) accordingly. - static size_t next_src_region(MoveAndUpdateClosure& closure, - SpaceId& src_space_id, - HeapWord*& src_space_top, - HeapWord* end_addr); - - // Decrement the destination count for each non-empty source region in the - // range [beg_region, region(region_align_up(end_addr))). If the destination - // count for a region goes to 0 and it needs to be filled, enqueue it. - static void decrement_destination_counts(ParCompactionManager* cm, - SpaceId src_space_id, - size_t beg_region, - HeapWord* end_addr); - - // Fill a region, copying objects from one or more source regions. - static void fill_region(ParCompactionManager* cm, size_t region_idx); - static void fill_and_update_region(ParCompactionManager* cm, size_t region) { - fill_region(cm, region); - } - - // Fill in the block table for the specified region. - static void fill_blocks(size_t region_idx); - - // Update the deferred objects in the space. - static void update_deferred_objects(ParCompactionManager* cm, SpaceId id); - - static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; } - static ParallelCompactData& summary_data() { return _summary_data; } - - // Reference Processing - static ReferenceProcessor* const ref_processor() { return _ref_processor; } - - static STWGCTimer* gc_timer() { return &_gc_timer; } - - // Return the SpaceId for the given address. - static SpaceId space_id(HeapWord* addr); - - // Time since last full gc (in milliseconds). - static jlong millis_since_last_gc(); - - static void print_on_error(outputStream* st); - -#ifndef PRODUCT - // Debugging support. - static const char* space_names[last_space_id]; - static void print_region_ranges(); - static void print_dense_prefix_stats(const char* const algorithm, - const SpaceId id, - const bool maximum_compaction, - HeapWord* const addr); - static void summary_phase_msg(SpaceId dst_space_id, - HeapWord* dst_beg, HeapWord* dst_end, - SpaceId src_space_id, - HeapWord* src_beg, HeapWord* src_end); -#endif // #ifndef PRODUCT - -#ifdef ASSERT - // Sanity check the new location of a word in the heap. - static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr); - // Verify that all the regions have been emptied. - static void verify_complete(SpaceId space_id); -#endif // #ifdef ASSERT -}; - -inline bool PSParallelCompact::mark_obj(oop obj) { - const int obj_size = obj->size(); - if (mark_bitmap()->mark_obj(obj, obj_size)) { - _summary_data.add_obj(obj, obj_size); - return true; - } else { - return false; - } -} - -inline bool PSParallelCompact::is_marked(oop obj) { - return mark_bitmap()->is_marked(obj); -} - -inline bool PSParallelCompact::print_phases() { - return _print_phases; -} - -inline double PSParallelCompact::normal_distribution(double density) { - assert(_dwl_initialized, "uninitialized"); - const double squared_term = (density - _dwl_mean) / _dwl_std_dev; - return _dwl_first_term * exp(-0.5 * squared_term * squared_term); -} - -inline bool -PSParallelCompact::dead_space_crosses_boundary(const RegionData* region, - idx_t bit) -{ - assert(bit > 0, "cannot call this for the first bit/region"); - assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit), - "sanity check"); - - // Dead space crosses the boundary if (1) a partial object does not extend - // onto the region, (2) an object does not start at the beginning of the - // region, and (3) an object does not end at the end of the prior region. - return region->partial_obj_size() == 0 && - !_mark_bitmap.is_obj_beg(bit) && - !_mark_bitmap.is_obj_end(bit - 1); -} - -inline bool -PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) { - return p >= beg_addr && p < end_addr; -} - -inline bool -PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) { - return is_in((HeapWord*)p, beg_addr, end_addr); -} - -inline MutableSpace* PSParallelCompact::space(SpaceId id) { - assert(id < last_space_id, "id out of range"); - return _space_info[id].space(); -} - -inline HeapWord* PSParallelCompact::new_top(SpaceId id) { - assert(id < last_space_id, "id out of range"); - return _space_info[id].new_top(); -} - -inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) { - assert(id < last_space_id, "id out of range"); - return _space_info[id].dense_prefix(); -} - -inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) { - assert(id < last_space_id, "id out of range"); - return _space_info[id].start_array(); -} - -#ifdef ASSERT -inline void -PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr) -{ - assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr), - "must move left or to a different space"); - assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr), - "checking alignment"); -} -#endif // ASSERT - -class MoveAndUpdateClosure: public ParMarkBitMapClosure { - public: - inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm, - ObjectStartArray* start_array, - HeapWord* destination, size_t words); - - // Accessors. - HeapWord* destination() const { return _destination; } - - // If the object will fit (size <= words_remaining()), copy it to the current - // destination, update the interior oops and the start array and return either - // full (if the closure is full) or incomplete. If the object will not fit, - // return would_overflow. - virtual IterationStatus do_addr(HeapWord* addr, size_t size); - - // Copy enough words to fill this closure, starting at source(). Interior - // oops and the start array are not updated. Return full. - IterationStatus copy_until_full(); - - // Copy enough words to fill this closure or to the end of an object, - // whichever is smaller, starting at source(). Interior oops and the start - // array are not updated. - void copy_partial_obj(); - - protected: - // Update variables to indicate that word_count words were processed. - inline void update_state(size_t word_count); - - protected: - ObjectStartArray* const _start_array; - HeapWord* _destination; // Next addr to be written. -}; - -inline -MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap, - ParCompactionManager* cm, - ObjectStartArray* start_array, - HeapWord* destination, - size_t words) : - ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array) -{ - _destination = destination; -} - -inline void MoveAndUpdateClosure::update_state(size_t words) -{ - decrement_words_remaining(words); - _source += words; - _destination += words; -} - -class UpdateOnlyClosure: public ParMarkBitMapClosure { - private: - const PSParallelCompact::SpaceId _space_id; - ObjectStartArray* const _start_array; - - public: - UpdateOnlyClosure(ParMarkBitMap* mbm, - ParCompactionManager* cm, - PSParallelCompact::SpaceId space_id); - - // Update the object. - virtual IterationStatus do_addr(HeapWord* addr, size_t words); - - inline void do_addr(HeapWord* addr); -}; - -class FillClosure: public ParMarkBitMapClosure -{ -public: - FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : - ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), - _start_array(PSParallelCompact::start_array(space_id)) - { - assert(space_id == PSParallelCompact::old_space_id, - "cannot use FillClosure in the young gen"); - } - - virtual IterationStatus do_addr(HeapWord* addr, size_t size) { - CollectedHeap::fill_with_objects(addr, size); - HeapWord* const end = addr + size; - do { - _start_array->allocate_block(addr); - addr += oop(addr)->size(); - } while (addr < end); - return ParMarkBitMap::incomplete; - } - -private: - ObjectStartArray* const _start_array; -}; - -#endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/parallel/psParallelCompact.hpp 2015-05-12 11:55:55.033467307 +0200 @@ -0,0 +1,1438 @@ +/* + * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#ifndef SHARE_VM_GC_PARALLEL_PSPARALLELCOMPACT_HPP +#define SHARE_VM_GC_PARALLEL_PSPARALLELCOMPACT_HPP + +#include "gc/parallel/objectStartArray.hpp" +#include "gc/parallel/parMarkBitMap.hpp" +#include "gc/parallel/parallelScavengeHeap.hpp" +#include "gc/shared/collectedHeap.hpp" +#include "gc/shared/collectorCounters.hpp" +#include "gc/shared/mutableSpace.hpp" +#include "oops/oop.hpp" + +class ParallelScavengeHeap; +class PSAdaptiveSizePolicy; +class PSYoungGen; +class PSOldGen; +class ParCompactionManager; +class ParallelTaskTerminator; +class PSParallelCompact; +class GCTaskManager; +class GCTaskQueue; +class PreGCValues; +class MoveAndUpdateClosure; +class RefProcTaskExecutor; +class ParallelOldTracer; +class STWGCTimer; + +// The SplitInfo class holds the information needed to 'split' a source region +// so that the live data can be copied to two destination *spaces*. Normally, +// all the live data in a region is copied to a single destination space (e.g., +// everything live in a region in eden is copied entirely into the old gen). +// However, when the heap is nearly full, all the live data in eden may not fit +// into the old gen. Copying only some of the regions from eden to old gen +// requires finding a region that does not contain a partial object (i.e., no +// live object crosses the region boundary) somewhere near the last object that +// does fit into the old gen. Since it's not always possible to find such a +// region, splitting is necessary for predictable behavior. +// +// A region is always split at the end of the partial object. This avoids +// additional tests when calculating the new location of a pointer, which is a +// very hot code path. The partial object and everything to its left will be +// copied to another space (call it dest_space_1). The live data to the right +// of the partial object will be copied either within the space itself, or to a +// different destination space (distinct from dest_space_1). +// +// Split points are identified during the summary phase, when region +// destinations are computed: data about the split, including the +// partial_object_size, is recorded in a SplitInfo record and the +// partial_object_size field in the summary data is set to zero. The zeroing is +// possible (and necessary) since the partial object will move to a different +// destination space than anything to its right, thus the partial object should +// not affect the locations of any objects to its right. +// +// The recorded data is used during the compaction phase, but only rarely: when +// the partial object on the split region will be copied across a destination +// region boundary. This test is made once each time a region is filled, and is +// a simple address comparison, so the overhead is negligible (see +// PSParallelCompact::first_src_addr()). +// +// Notes: +// +// Only regions with partial objects are split; a region without a partial +// object does not need any extra bookkeeping. +// +// At most one region is split per space, so the amount of data required is +// constant. +// +// A region is split only when the destination space would overflow. Once that +// happens, the destination space is abandoned and no other data (even from +// other source spaces) is targeted to that destination space. Abandoning the +// destination space may leave a somewhat large unused area at the end, if a +// large object caused the overflow. +// +// Future work: +// +// More bookkeeping would be required to continue to use the destination space. +// The most general solution would allow data from regions in two different +// source spaces to be "joined" in a single destination region. At the very +// least, additional code would be required in next_src_region() to detect the +// join and skip to an out-of-order source region. If the join region was also +// the last destination region to which a split region was copied (the most +// likely case), then additional work would be needed to get fill_region() to +// stop iteration and switch to a new source region at the right point. Basic +// idea would be to use a fake value for the top of the source space. It is +// doable, if a bit tricky. +// +// A simpler (but less general) solution would fill the remainder of the +// destination region with a dummy object and continue filling the next +// destination region. + +class SplitInfo +{ +public: + // Return true if this split info is valid (i.e., if a split has been + // recorded). The very first region cannot have a partial object and thus is + // never split, so 0 is the 'invalid' value. + bool is_valid() const { return _src_region_idx > 0; } + + // Return true if this split holds data for the specified source region. + inline bool is_split(size_t source_region) const; + + // The index of the split region, the size of the partial object on that + // region and the destination of the partial object. + size_t src_region_idx() const { return _src_region_idx; } + size_t partial_obj_size() const { return _partial_obj_size; } + HeapWord* destination() const { return _destination; } + + // The destination count of the partial object referenced by this split + // (either 1 or 2). This must be added to the destination count of the + // remainder of the source region. + unsigned int destination_count() const { return _destination_count; } + + // If a word within the partial object will be written to the first word of a + // destination region, this is the address of the destination region; + // otherwise this is NULL. + HeapWord* dest_region_addr() const { return _dest_region_addr; } + + // If a word within the partial object will be written to the first word of a + // destination region, this is the address of that word within the partial + // object; otherwise this is NULL. + HeapWord* first_src_addr() const { return _first_src_addr; } + + // Record the data necessary to split the region src_region_idx. + void record(size_t src_region_idx, size_t partial_obj_size, + HeapWord* destination); + + void clear(); + + DEBUG_ONLY(void verify_clear();) + +private: + size_t _src_region_idx; + size_t _partial_obj_size; + HeapWord* _destination; + unsigned int _destination_count; + HeapWord* _dest_region_addr; + HeapWord* _first_src_addr; +}; + +inline bool SplitInfo::is_split(size_t region_idx) const +{ + return _src_region_idx == region_idx && is_valid(); +} + +class SpaceInfo +{ + public: + MutableSpace* space() const { return _space; } + + // Where the free space will start after the collection. Valid only after the + // summary phase completes. + HeapWord* new_top() const { return _new_top; } + + // Allows new_top to be set. + HeapWord** new_top_addr() { return &_new_top; } + + // Where the smallest allowable dense prefix ends (used only for perm gen). + HeapWord* min_dense_prefix() const { return _min_dense_prefix; } + + // Where the dense prefix ends, or the compacted region begins. + HeapWord* dense_prefix() const { return _dense_prefix; } + + // The start array for the (generation containing the) space, or NULL if there + // is no start array. + ObjectStartArray* start_array() const { return _start_array; } + + SplitInfo& split_info() { return _split_info; } + + void set_space(MutableSpace* s) { _space = s; } + void set_new_top(HeapWord* addr) { _new_top = addr; } + void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; } + void set_dense_prefix(HeapWord* addr) { _dense_prefix = addr; } + void set_start_array(ObjectStartArray* s) { _start_array = s; } + + void publish_new_top() const { _space->set_top(_new_top); } + + private: + MutableSpace* _space; + HeapWord* _new_top; + HeapWord* _min_dense_prefix; + HeapWord* _dense_prefix; + ObjectStartArray* _start_array; + SplitInfo _split_info; +}; + +class ParallelCompactData +{ +public: + // Sizes are in HeapWords, unless indicated otherwise. + static const size_t Log2RegionSize; + static const size_t RegionSize; + static const size_t RegionSizeBytes; + + // Mask for the bits in a size_t to get an offset within a region. + static const size_t RegionSizeOffsetMask; + // Mask for the bits in a pointer to get an offset within a region. + static const size_t RegionAddrOffsetMask; + // Mask for the bits in a pointer to get the address of the start of a region. + static const size_t RegionAddrMask; + + static const size_t Log2BlockSize; + static const size_t BlockSize; + static const size_t BlockSizeBytes; + + static const size_t BlockSizeOffsetMask; + static const size_t BlockAddrOffsetMask; + static const size_t BlockAddrMask; + + static const size_t BlocksPerRegion; + static const size_t Log2BlocksPerRegion; + + class RegionData + { + public: + // Destination address of the region. + HeapWord* destination() const { return _destination; } + + // The first region containing data destined for this region. + size_t source_region() const { return _source_region; } + + // The object (if any) starting in this region and ending in a different + // region that could not be updated during the main (parallel) compaction + // phase. This is different from _partial_obj_addr, which is an object that + // extends onto a source region. However, the two uses do not overlap in + // time, so the same field is used to save space. + HeapWord* deferred_obj_addr() const { return _partial_obj_addr; } + + // The starting address of the partial object extending onto the region. + HeapWord* partial_obj_addr() const { return _partial_obj_addr; } + + // Size of the partial object extending onto the region (words). + size_t partial_obj_size() const { return _partial_obj_size; } + + // Size of live data that lies within this region due to objects that start + // in this region (words). This does not include the partial object + // extending onto the region (if any), or the part of an object that extends + // onto the next region (if any). + size_t live_obj_size() const { return _dc_and_los & los_mask; } + + // Total live data that lies within the region (words). + size_t data_size() const { return partial_obj_size() + live_obj_size(); } + + // The destination_count is the number of other regions to which data from + // this region will be copied. At the end of the summary phase, the valid + // values of destination_count are + // + // 0 - data from the region will be compacted completely into itself, or the + // region is empty. The region can be claimed and then filled. + // 1 - data from the region will be compacted into 1 other region; some + // data from the region may also be compacted into the region itself. + // 2 - data from the region will be copied to 2 other regions. + // + // During compaction as regions are emptied, the destination_count is + // decremented (atomically) and when it reaches 0, it can be claimed and + // then filled. + // + // A region is claimed for processing by atomically changing the + // destination_count to the claimed value (dc_claimed). After a region has + // been filled, the destination_count should be set to the completed value + // (dc_completed). + inline uint destination_count() const; + inline uint destination_count_raw() const; + + // Whether the block table for this region has been filled. + inline bool blocks_filled() const; + + // Number of times the block table was filled. + DEBUG_ONLY(inline size_t blocks_filled_count() const;) + + // The location of the java heap data that corresponds to this region. + inline HeapWord* data_location() const; + + // The highest address referenced by objects in this region. + inline HeapWord* highest_ref() const; + + // Whether this region is available to be claimed, has been claimed, or has + // been completed. + // + // Minor subtlety: claimed() returns true if the region is marked + // completed(), which is desirable since a region must be claimed before it + // can be completed. + bool available() const { return _dc_and_los < dc_one; } + bool claimed() const { return _dc_and_los >= dc_claimed; } + bool completed() const { return _dc_and_los >= dc_completed; } + + // These are not atomic. + void set_destination(HeapWord* addr) { _destination = addr; } + void set_source_region(size_t region) { _source_region = region; } + void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } + void set_partial_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; } + void set_partial_obj_size(size_t words) { + _partial_obj_size = (region_sz_t) words; + } + inline void set_blocks_filled(); + + inline void set_destination_count(uint count); + inline void set_live_obj_size(size_t words); + inline void set_data_location(HeapWord* addr); + inline void set_completed(); + inline bool claim_unsafe(); + + // These are atomic. + inline void add_live_obj(size_t words); + inline void set_highest_ref(HeapWord* addr); + inline void decrement_destination_count(); + inline bool claim(); + + private: + // The type used to represent object sizes within a region. + typedef uint region_sz_t; + + // Constants for manipulating the _dc_and_los field, which holds both the + // destination count and live obj size. The live obj size lives at the + // least significant end so no masking is necessary when adding. + static const region_sz_t dc_shift; // Shift amount. + static const region_sz_t dc_mask; // Mask for destination count. + static const region_sz_t dc_one; // 1, shifted appropriately. + static const region_sz_t dc_claimed; // Region has been claimed. + static const region_sz_t dc_completed; // Region has been completed. + static const region_sz_t los_mask; // Mask for live obj size. + + HeapWord* _destination; + size_t _source_region; + HeapWord* _partial_obj_addr; + region_sz_t _partial_obj_size; + region_sz_t volatile _dc_and_los; + bool _blocks_filled; + +#ifdef ASSERT + size_t _blocks_filled_count; // Number of block table fills. + + // These enable optimizations that are only partially implemented. Use + // debug builds to prevent the code fragments from breaking. + HeapWord* _data_location; + HeapWord* _highest_ref; +#endif // #ifdef ASSERT + +#ifdef ASSERT + public: + uint _pushed; // 0 until region is pushed onto a stack + private: +#endif + }; + + // "Blocks" allow shorter sections of the bitmap to be searched. Each Block + // holds an offset, which is the amount of live data in the Region to the left + // of the first live object that starts in the Block. + class BlockData + { + public: + typedef unsigned short int blk_ofs_t; + + blk_ofs_t offset() const { return _offset; } + void set_offset(size_t val) { _offset = (blk_ofs_t)val; } + + private: + blk_ofs_t _offset; + }; + +public: + ParallelCompactData(); + bool initialize(MemRegion covered_region); + + size_t region_count() const { return _region_count; } + size_t reserved_byte_size() const { return _reserved_byte_size; } + + // Convert region indices to/from RegionData pointers. + inline RegionData* region(size_t region_idx) const; + inline size_t region(const RegionData* const region_ptr) const; + + size_t block_count() const { return _block_count; } + inline BlockData* block(size_t block_idx) const; + inline size_t block(const BlockData* block_ptr) const; + + void add_obj(HeapWord* addr, size_t len); + void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); } + + // Fill in the regions covering [beg, end) so that no data moves; i.e., the + // destination of region n is simply the start of region n. The argument beg + // must be region-aligned; end need not be. + void summarize_dense_prefix(HeapWord* beg, HeapWord* end); + + HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info, + HeapWord* destination, HeapWord* target_end, + HeapWord** target_next); + bool summarize(SplitInfo& split_info, + HeapWord* source_beg, HeapWord* source_end, + HeapWord** source_next, + HeapWord* target_beg, HeapWord* target_end, + HeapWord** target_next); + + void clear(); + void clear_range(size_t beg_region, size_t end_region); + void clear_range(HeapWord* beg, HeapWord* end) { + clear_range(addr_to_region_idx(beg), addr_to_region_idx(end)); + } + + // Return the number of words between addr and the start of the region + // containing addr. + inline size_t region_offset(const HeapWord* addr) const; + + // Convert addresses to/from a region index or region pointer. + inline size_t addr_to_region_idx(const HeapWord* addr) const; + inline RegionData* addr_to_region_ptr(const HeapWord* addr) const; + inline HeapWord* region_to_addr(size_t region) const; + inline HeapWord* region_to_addr(size_t region, size_t offset) const; + inline HeapWord* region_to_addr(const RegionData* region) const; + + inline HeapWord* region_align_down(HeapWord* addr) const; + inline HeapWord* region_align_up(HeapWord* addr) const; + inline bool is_region_aligned(HeapWord* addr) const; + + // Analogous to region_offset() for blocks. + size_t block_offset(const HeapWord* addr) const; + size_t addr_to_block_idx(const HeapWord* addr) const; + size_t addr_to_block_idx(const oop obj) const { + return addr_to_block_idx((HeapWord*) obj); + } + inline BlockData* addr_to_block_ptr(const HeapWord* addr) const; + inline HeapWord* block_to_addr(size_t block) const; + inline size_t region_to_block_idx(size_t region) const; + + inline HeapWord* block_align_down(HeapWord* addr) const; + inline HeapWord* block_align_up(HeapWord* addr) const; + inline bool is_block_aligned(HeapWord* addr) const; + + // Return the address one past the end of the partial object. + HeapWord* partial_obj_end(size_t region_idx) const; + + // Return the location of the object after compaction. + HeapWord* calc_new_pointer(HeapWord* addr); + + HeapWord* calc_new_pointer(oop p) { + return calc_new_pointer((HeapWord*) p); + } + +#ifdef ASSERT + void verify_clear(const PSVirtualSpace* vspace); + void verify_clear(); +#endif // #ifdef ASSERT + +private: + bool initialize_block_data(); + bool initialize_region_data(size_t region_size); + PSVirtualSpace* create_vspace(size_t count, size_t element_size); + +private: + HeapWord* _region_start; +#ifdef ASSERT + HeapWord* _region_end; +#endif // #ifdef ASSERT + + PSVirtualSpace* _region_vspace; + size_t _reserved_byte_size; + RegionData* _region_data; + size_t _region_count; + + PSVirtualSpace* _block_vspace; + BlockData* _block_data; + size_t _block_count; +}; + +inline uint +ParallelCompactData::RegionData::destination_count_raw() const +{ + return _dc_and_los & dc_mask; +} + +inline uint +ParallelCompactData::RegionData::destination_count() const +{ + return destination_count_raw() >> dc_shift; +} + +inline bool +ParallelCompactData::RegionData::blocks_filled() const +{ + return _blocks_filled; +} + +#ifdef ASSERT +inline size_t +ParallelCompactData::RegionData::blocks_filled_count() const +{ + return _blocks_filled_count; +} +#endif // #ifdef ASSERT + +inline void +ParallelCompactData::RegionData::set_blocks_filled() +{ + _blocks_filled = true; + // Debug builds count the number of times the table was filled. + DEBUG_ONLY(Atomic::inc_ptr(&_blocks_filled_count)); +} + +inline void +ParallelCompactData::RegionData::set_destination_count(uint count) +{ + assert(count <= (dc_completed >> dc_shift), "count too large"); + const region_sz_t live_sz = (region_sz_t) live_obj_size(); + _dc_and_los = (count << dc_shift) | live_sz; +} + +inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words) +{ + assert(words <= los_mask, "would overflow"); + _dc_and_los = destination_count_raw() | (region_sz_t)words; +} + +inline void ParallelCompactData::RegionData::decrement_destination_count() +{ + assert(_dc_and_los < dc_claimed, "already claimed"); + assert(_dc_and_los >= dc_one, "count would go negative"); + Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los); +} + +inline HeapWord* ParallelCompactData::RegionData::data_location() const +{ + DEBUG_ONLY(return _data_location;) + NOT_DEBUG(return NULL;) +} + +inline HeapWord* ParallelCompactData::RegionData::highest_ref() const +{ + DEBUG_ONLY(return _highest_ref;) + NOT_DEBUG(return NULL;) +} + +inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr) +{ + DEBUG_ONLY(_data_location = addr;) +} + +inline void ParallelCompactData::RegionData::set_completed() +{ + assert(claimed(), "must be claimed first"); + _dc_and_los = dc_completed | (region_sz_t) live_obj_size(); +} + +// MT-unsafe claiming of a region. Should only be used during single threaded +// execution. +inline bool ParallelCompactData::RegionData::claim_unsafe() +{ + if (available()) { + _dc_and_los |= dc_claimed; + return true; + } + return false; +} + +inline void ParallelCompactData::RegionData::add_live_obj(size_t words) +{ + assert(words <= (size_t)los_mask - live_obj_size(), "overflow"); + Atomic::add((int) words, (volatile int*) &_dc_and_los); +} + +inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr) +{ +#ifdef ASSERT + HeapWord* tmp = _highest_ref; + while (addr > tmp) { + tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp); + } +#endif // #ifdef ASSERT +} + +inline bool ParallelCompactData::RegionData::claim() +{ + const int los = (int) live_obj_size(); + const int old = Atomic::cmpxchg(dc_claimed | los, + (volatile int*) &_dc_and_los, los); + return old == los; +} + +inline ParallelCompactData::RegionData* +ParallelCompactData::region(size_t region_idx) const +{ + assert(region_idx <= region_count(), "bad arg"); + return _region_data + region_idx; +} + +inline size_t +ParallelCompactData::region(const RegionData* const region_ptr) const +{ + assert(region_ptr >= _region_data, "bad arg"); + assert(region_ptr <= _region_data + region_count(), "bad arg"); + return pointer_delta(region_ptr, _region_data, sizeof(RegionData)); +} + +inline ParallelCompactData::BlockData* +ParallelCompactData::block(size_t n) const { + assert(n < block_count(), "bad arg"); + return _block_data + n; +} + +inline size_t +ParallelCompactData::region_offset(const HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr <= _region_end, "bad addr"); + return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize; +} + +inline size_t +ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr <= _region_end, "bad addr"); + return pointer_delta(addr, _region_start) >> Log2RegionSize; +} + +inline ParallelCompactData::RegionData* +ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const +{ + return region(addr_to_region_idx(addr)); +} + +inline HeapWord* +ParallelCompactData::region_to_addr(size_t region) const +{ + assert(region <= _region_count, "region out of range"); + return _region_start + (region << Log2RegionSize); +} + +inline HeapWord* +ParallelCompactData::region_to_addr(const RegionData* region) const +{ + return region_to_addr(pointer_delta(region, _region_data, + sizeof(RegionData))); +} + +inline HeapWord* +ParallelCompactData::region_to_addr(size_t region, size_t offset) const +{ + assert(region <= _region_count, "region out of range"); + assert(offset < RegionSize, "offset too big"); // This may be too strict. + return region_to_addr(region) + offset; +} + +inline HeapWord* +ParallelCompactData::region_align_down(HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr < _region_end + RegionSize, "bad addr"); + return (HeapWord*)(size_t(addr) & RegionAddrMask); +} + +inline HeapWord* +ParallelCompactData::region_align_up(HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr <= _region_end, "bad addr"); + return region_align_down(addr + RegionSizeOffsetMask); +} + +inline bool +ParallelCompactData::is_region_aligned(HeapWord* addr) const +{ + return region_offset(addr) == 0; +} + +inline size_t +ParallelCompactData::block_offset(const HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr <= _region_end, "bad addr"); + return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize; +} + +inline size_t +ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr <= _region_end, "bad addr"); + return pointer_delta(addr, _region_start) >> Log2BlockSize; +} + +inline ParallelCompactData::BlockData* +ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const +{ + return block(addr_to_block_idx(addr)); +} + +inline HeapWord* +ParallelCompactData::block_to_addr(size_t block) const +{ + assert(block < _block_count, "block out of range"); + return _region_start + (block << Log2BlockSize); +} + +inline size_t +ParallelCompactData::region_to_block_idx(size_t region) const +{ + return region << Log2BlocksPerRegion; +} + +inline HeapWord* +ParallelCompactData::block_align_down(HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr < _region_end + RegionSize, "bad addr"); + return (HeapWord*)(size_t(addr) & BlockAddrMask); +} + +inline HeapWord* +ParallelCompactData::block_align_up(HeapWord* addr) const +{ + assert(addr >= _region_start, "bad addr"); + assert(addr <= _region_end, "bad addr"); + return block_align_down(addr + BlockSizeOffsetMask); +} + +inline bool +ParallelCompactData::is_block_aligned(HeapWord* addr) const +{ + return block_offset(addr) == 0; +} + +// Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the +// do_addr() method. +// +// The closure is initialized with the number of heap words to process +// (words_remaining()), and becomes 'full' when it reaches 0. The do_addr() +// methods in subclasses should update the total as words are processed. Since +// only one subclass actually uses this mechanism to terminate iteration, the +// default initial value is > 0. The implementation is here and not in the +// single subclass that uses it to avoid making is_full() virtual, and thus +// adding a virtual call per live object. + +class ParMarkBitMapClosure: public StackObj { + public: + typedef ParMarkBitMap::idx_t idx_t; + typedef ParMarkBitMap::IterationStatus IterationStatus; + + public: + inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm, + size_t words = max_uintx); + + inline ParCompactionManager* compaction_manager() const; + inline ParMarkBitMap* bitmap() const; + inline size_t words_remaining() const; + inline bool is_full() const; + inline HeapWord* source() const; + + inline void set_source(HeapWord* addr); + + virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0; + + protected: + inline void decrement_words_remaining(size_t words); + + private: + ParMarkBitMap* const _bitmap; + ParCompactionManager* const _compaction_manager; + DEBUG_ONLY(const size_t _initial_words_remaining;) // Useful in debugger. + size_t _words_remaining; // Words left to copy. + + protected: + HeapWord* _source; // Next addr that would be read. +}; + +inline +ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap, + ParCompactionManager* cm, + size_t words): + _bitmap(bitmap), _compaction_manager(cm) +#ifdef ASSERT + , _initial_words_remaining(words) +#endif +{ + _words_remaining = words; + _source = NULL; +} + +inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const { + return _compaction_manager; +} + +inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const { + return _bitmap; +} + +inline size_t ParMarkBitMapClosure::words_remaining() const { + return _words_remaining; +} + +inline bool ParMarkBitMapClosure::is_full() const { + return words_remaining() == 0; +} + +inline HeapWord* ParMarkBitMapClosure::source() const { + return _source; +} + +inline void ParMarkBitMapClosure::set_source(HeapWord* addr) { + _source = addr; +} + +inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) { + assert(_words_remaining >= words, "processed too many words"); + _words_remaining -= words; +} + +// The UseParallelOldGC collector is a stop-the-world garbage collector that +// does parts of the collection using parallel threads. The collection includes +// the tenured generation and the young generation. The permanent generation is +// collected at the same time as the other two generations but the permanent +// generation is collect by a single GC thread. The permanent generation is +// collected serially because of the requirement that during the processing of a +// klass AAA, any objects reference by AAA must already have been processed. +// This requirement is enforced by a left (lower address) to right (higher +// address) sliding compaction. +// +// There are four phases of the collection. +// +// - marking phase +// - summary phase +// - compacting phase +// - clean up phase +// +// Roughly speaking these phases correspond, respectively, to +// - mark all the live objects +// - calculate the destination of each object at the end of the collection +// - move the objects to their destination +// - update some references and reinitialize some variables +// +// These three phases are invoked in PSParallelCompact::invoke_no_policy(). The +// marking phase is implemented in PSParallelCompact::marking_phase() and does a +// complete marking of the heap. The summary phase is implemented in +// PSParallelCompact::summary_phase(). The move and update phase is implemented +// in PSParallelCompact::compact(). +// +// A space that is being collected is divided into regions and with each region +// is associated an object of type ParallelCompactData. Each region is of a +// fixed size and typically will contain more than 1 object and may have parts +// of objects at the front and back of the region. +// +// region -----+---------------------+---------- +// objects covered [ AAA )[ BBB )[ CCC )[ DDD ) +// +// The marking phase does a complete marking of all live objects in the heap. +// The marking also compiles the size of the data for all live objects covered +// by the region. This size includes the part of any live object spanning onto +// the region (part of AAA if it is live) from the front, all live objects +// contained in the region (BBB and/or CCC if they are live), and the part of +// any live objects covered by the region that extends off the region (part of +// DDD if it is live). The marking phase uses multiple GC threads and marking +// is done in a bit array of type ParMarkBitMap. The marking of the bit map is +// done atomically as is the accumulation of the size of the live objects +// covered by a region. +// +// The summary phase calculates the total live data to the left of each region +// XXX. Based on that total and the bottom of the space, it can calculate the +// starting location of the live data in XXX. The summary phase calculates for +// each region XXX quantities such as +// +// - the amount of live data at the beginning of a region from an object +// entering the region. +// - the location of the first live data on the region +// - a count of the number of regions receiving live data from XXX. +// +// See ParallelCompactData for precise details. The summary phase also +// calculates the dense prefix for the compaction. The dense prefix is a +// portion at the beginning of the space that is not moved. The objects in the +// dense prefix do need to have their object references updated. See method +// summarize_dense_prefix(). +// +// The summary phase is done using 1 GC thread. +// +// The compaction phase moves objects to their new location and updates all +// references in the object. +// +// A current exception is that objects that cross a region boundary are moved +// but do not have their references updated. References are not updated because +// it cannot easily be determined if the klass pointer KKK for the object AAA +// has been updated. KKK likely resides in a region to the left of the region +// containing AAA. These AAA's have there references updated at the end in a +// clean up phase. See the method PSParallelCompact::update_deferred_objects(). +// An alternate strategy is being investigated for this deferral of updating. +// +// Compaction is done on a region basis. A region that is ready to be filled is +// put on a ready list and GC threads take region off the list and fill them. A +// region is ready to be filled if it empty of live objects. Such a region may +// have been initially empty (only contained dead objects) or may have had all +// its live objects copied out already. A region that compacts into itself is +// also ready for filling. The ready list is initially filled with empty +// regions and regions compacting into themselves. There is always at least 1 +// region that can be put on the ready list. The regions are atomically added +// and removed from the ready list. + +class PSParallelCompact : AllStatic { + public: + // Convenient access to type names. + typedef ParMarkBitMap::idx_t idx_t; + typedef ParallelCompactData::RegionData RegionData; + typedef ParallelCompactData::BlockData BlockData; + + typedef enum { + old_space_id, eden_space_id, + from_space_id, to_space_id, last_space_id + } SpaceId; + + public: + // Inline closure decls + // + class IsAliveClosure: public BoolObjectClosure { + public: + virtual bool do_object_b(oop p); + }; + + class AdjustPointerClosure: public ExtendedOopClosure { + public: + template void do_oop_nv(T* p); + virtual void do_oop(oop* p); + virtual void do_oop(narrowOop* p); + + // This closure provides its own oop verification code. + debug_only(virtual bool should_verify_oops() { return false; }) + }; + + class AdjustKlassClosure : public KlassClosure { + public: + void do_klass(Klass* klass); + }; + + friend class AdjustPointerClosure; + friend class AdjustKlassClosure; + friend class RefProcTaskProxy; + + private: + static STWGCTimer _gc_timer; + static ParallelOldTracer _gc_tracer; + static elapsedTimer _accumulated_time; + static unsigned int _total_invocations; + static unsigned int _maximum_compaction_gc_num; + static jlong _time_of_last_gc; // ms + static CollectorCounters* _counters; + static ParMarkBitMap _mark_bitmap; + static ParallelCompactData _summary_data; + static IsAliveClosure _is_alive_closure; + static SpaceInfo _space_info[last_space_id]; + static bool _print_phases; + static AdjustPointerClosure _adjust_pointer_closure; + static AdjustKlassClosure _adjust_klass_closure; + + // Reference processing (used in ...follow_contents) + static ReferenceProcessor* _ref_processor; + + // Values computed at initialization and used by dead_wood_limiter(). + static double _dwl_mean; + static double _dwl_std_dev; + static double _dwl_first_term; + static double _dwl_adjustment; +#ifdef ASSERT + static bool _dwl_initialized; +#endif // #ifdef ASSERT + + + public: + static ParallelOldTracer* gc_tracer() { return &_gc_tracer; } + + private: + + static void initialize_space_info(); + + // Return true if details about individual phases should be printed. + static inline bool print_phases(); + + // Clear the marking bitmap and summary data that cover the specified space. + static void clear_data_covering_space(SpaceId id); + + static void pre_compact(PreGCValues* pre_gc_values); + static void post_compact(); + + // Mark live objects + static void marking_phase(ParCompactionManager* cm, + bool maximum_heap_compaction, + ParallelOldTracer *gc_tracer); + + // Compute the dense prefix for the designated space. This is an experimental + // implementation currently not used in production. + static HeapWord* compute_dense_prefix_via_density(const SpaceId id, + bool maximum_compaction); + + // Methods used to compute the dense prefix. + + // Compute the value of the normal distribution at x = density. The mean and + // standard deviation are values saved by initialize_dead_wood_limiter(). + static inline double normal_distribution(double density); + + // Initialize the static vars used by dead_wood_limiter(). + static void initialize_dead_wood_limiter(); + + // Return the percentage of space that can be treated as "dead wood" (i.e., + // not reclaimed). + static double dead_wood_limiter(double density, size_t min_percent); + + // Find the first (left-most) region in the range [beg, end) that has at least + // dead_words of dead space to the left. The argument beg must be the first + // region in the space that is not completely live. + static RegionData* dead_wood_limit_region(const RegionData* beg, + const RegionData* end, + size_t dead_words); + + // Return a pointer to the first region in the range [beg, end) that is not + // completely full. + static RegionData* first_dead_space_region(const RegionData* beg, + const RegionData* end); + + // Return a value indicating the benefit or 'yield' if the compacted region + // were to start (or equivalently if the dense prefix were to end) at the + // candidate region. Higher values are better. + // + // The value is based on the amount of space reclaimed vs. the costs of (a) + // updating references in the dense prefix plus (b) copying objects and + // updating references in the compacted region. + static inline double reclaimed_ratio(const RegionData* const candidate, + HeapWord* const bottom, + HeapWord* const top, + HeapWord* const new_top); + + // Compute the dense prefix for the designated space. + static HeapWord* compute_dense_prefix(const SpaceId id, + bool maximum_compaction); + + // Return true if dead space crosses onto the specified Region; bit must be + // the bit index corresponding to the first word of the Region. + static inline bool dead_space_crosses_boundary(const RegionData* region, + idx_t bit); + + // Summary phase utility routine to fill dead space (if any) at the dense + // prefix boundary. Should only be called if the the dense prefix is + // non-empty. + static void fill_dense_prefix_end(SpaceId id); + + // Clear the summary data source_region field for the specified addresses. + static void clear_source_region(HeapWord* beg_addr, HeapWord* end_addr); + +#ifndef PRODUCT + // Routines to provoke splitting a young gen space (ParallelOldGCSplitALot). + + // Fill the region [start, start + words) with live object(s). Only usable + // for the old and permanent generations. + static void fill_with_live_objects(SpaceId id, HeapWord* const start, + size_t words); + // Include the new objects in the summary data. + static void summarize_new_objects(SpaceId id, HeapWord* start); + + // Add live objects to a survivor space since it's rare that both survivors + // are non-empty. + static void provoke_split_fill_survivor(SpaceId id); + + // Add live objects and/or choose the dense prefix to provoke splitting. + static void provoke_split(bool & maximum_compaction); +#endif + + static void summarize_spaces_quick(); + static void summarize_space(SpaceId id, bool maximum_compaction); + static void summary_phase(ParCompactionManager* cm, bool maximum_compaction); + + // Adjust addresses in roots. Does not adjust addresses in heap. + static void adjust_roots(); + + DEBUG_ONLY(static void write_block_fill_histogram(outputStream* const out);) + + // Move objects to new locations. + static void compact_perm(ParCompactionManager* cm); + static void compact(); + + // Add available regions to the stack and draining tasks to the task queue. + static void enqueue_region_draining_tasks(GCTaskQueue* q, + uint parallel_gc_threads); + + // Add dense prefix update tasks to the task queue. + static void enqueue_dense_prefix_tasks(GCTaskQueue* q, + uint parallel_gc_threads); + + // Add region stealing tasks to the task queue. + static void enqueue_region_stealing_tasks( + GCTaskQueue* q, + ParallelTaskTerminator* terminator_ptr, + uint parallel_gc_threads); + + // If objects are left in eden after a collection, try to move the boundary + // and absorb them into the old gen. Returns true if eden was emptied. + static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy, + PSYoungGen* young_gen, + PSOldGen* old_gen); + + // Reset time since last full gc + static void reset_millis_since_last_gc(); + + public: + + PSParallelCompact(); + + static void invoke(bool maximum_heap_compaction); + static bool invoke_no_policy(bool maximum_heap_compaction); + + static void post_initialize(); + // Perform initialization for PSParallelCompact that requires + // allocations. This should be called during the VM initialization + // at a pointer where it would be appropriate to return a JNI_ENOMEM + // in the event of a failure. + static bool initialize(); + + // Closure accessors + static PSParallelCompact::AdjustPointerClosure* adjust_pointer_closure() { + return &_adjust_pointer_closure; + } + static KlassClosure* adjust_klass_closure() { return (KlassClosure*)&_adjust_klass_closure; } + static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; } + + // Public accessors + static elapsedTimer* accumulated_time() { return &_accumulated_time; } + static unsigned int total_invocations() { return _total_invocations; } + static CollectorCounters* counters() { return _counters; } + + // Used to add tasks + static GCTaskManager* const gc_task_manager(); + + // Marking support + static inline bool mark_obj(oop obj); + static inline bool is_marked(oop obj); + + template static inline void adjust_pointer(T* p); + + // Compaction support. + // Return true if p is in the range [beg_addr, end_addr). + static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr); + static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr); + + // Convenience wrappers for per-space data kept in _space_info. + static inline MutableSpace* space(SpaceId space_id); + static inline HeapWord* new_top(SpaceId space_id); + static inline HeapWord* dense_prefix(SpaceId space_id); + static inline ObjectStartArray* start_array(SpaceId space_id); + + // Move and update the live objects in the specified space. + static void move_and_update(ParCompactionManager* cm, SpaceId space_id); + + // Process the end of the given region range in the dense prefix. + // This includes saving any object not updated. + static void dense_prefix_regions_epilogue(ParCompactionManager* cm, + size_t region_start_index, + size_t region_end_index, + idx_t exiting_object_offset, + idx_t region_offset_start, + idx_t region_offset_end); + + // Update a region in the dense prefix. For each live object + // in the region, update it's interior references. For each + // dead object, fill it with deadwood. Dead space at the end + // of a region range will be filled to the start of the next + // live object regardless of the region_index_end. None of the + // objects in the dense prefix move and dead space is dead + // (holds only dead objects that don't need any processing), so + // dead space can be filled in any order. + static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm, + SpaceId space_id, + size_t region_index_start, + size_t region_index_end); + + // Return the address of the count + 1st live word in the range [beg, end). + static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count); + + // Return the address of the word to be copied to dest_addr, which must be + // aligned to a region boundary. + static HeapWord* first_src_addr(HeapWord* const dest_addr, + SpaceId src_space_id, + size_t src_region_idx); + + // Determine the next source region, set closure.source() to the start of the + // new region return the region index. Parameter end_addr is the address one + // beyond the end of source range just processed. If necessary, switch to a + // new source space and set src_space_id (in-out parameter) and src_space_top + // (out parameter) accordingly. + static size_t next_src_region(MoveAndUpdateClosure& closure, + SpaceId& src_space_id, + HeapWord*& src_space_top, + HeapWord* end_addr); + + // Decrement the destination count for each non-empty source region in the + // range [beg_region, region(region_align_up(end_addr))). If the destination + // count for a region goes to 0 and it needs to be filled, enqueue it. + static void decrement_destination_counts(ParCompactionManager* cm, + SpaceId src_space_id, + size_t beg_region, + HeapWord* end_addr); + + // Fill a region, copying objects from one or more source regions. + static void fill_region(ParCompactionManager* cm, size_t region_idx); + static void fill_and_update_region(ParCompactionManager* cm, size_t region) { + fill_region(cm, region); + } + + // Fill in the block table for the specified region. + static void fill_blocks(size_t region_idx); + + // Update the deferred objects in the space. + static void update_deferred_objects(ParCompactionManager* cm, SpaceId id); + + static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; } + static ParallelCompactData& summary_data() { return _summary_data; } + + // Reference Processing + static ReferenceProcessor* const ref_processor() { return _ref_processor; } + + static STWGCTimer* gc_timer() { return &_gc_timer; } + + // Return the SpaceId for the given address. + static SpaceId space_id(HeapWord* addr); + + // Time since last full gc (in milliseconds). + static jlong millis_since_last_gc(); + + static void print_on_error(outputStream* st); + +#ifndef PRODUCT + // Debugging support. + static const char* space_names[last_space_id]; + static void print_region_ranges(); + static void print_dense_prefix_stats(const char* const algorithm, + const SpaceId id, + const bool maximum_compaction, + HeapWord* const addr); + static void summary_phase_msg(SpaceId dst_space_id, + HeapWord* dst_beg, HeapWord* dst_end, + SpaceId src_space_id, + HeapWord* src_beg, HeapWord* src_end); +#endif // #ifndef PRODUCT + +#ifdef ASSERT + // Sanity check the new location of a word in the heap. + static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr); + // Verify that all the regions have been emptied. + static void verify_complete(SpaceId space_id); +#endif // #ifdef ASSERT +}; + +inline bool PSParallelCompact::mark_obj(oop obj) { + const int obj_size = obj->size(); + if (mark_bitmap()->mark_obj(obj, obj_size)) { + _summary_data.add_obj(obj, obj_size); + return true; + } else { + return false; + } +} + +inline bool PSParallelCompact::is_marked(oop obj) { + return mark_bitmap()->is_marked(obj); +} + +inline bool PSParallelCompact::print_phases() { + return _print_phases; +} + +inline double PSParallelCompact::normal_distribution(double density) { + assert(_dwl_initialized, "uninitialized"); + const double squared_term = (density - _dwl_mean) / _dwl_std_dev; + return _dwl_first_term * exp(-0.5 * squared_term * squared_term); +} + +inline bool +PSParallelCompact::dead_space_crosses_boundary(const RegionData* region, + idx_t bit) +{ + assert(bit > 0, "cannot call this for the first bit/region"); + assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit), + "sanity check"); + + // Dead space crosses the boundary if (1) a partial object does not extend + // onto the region, (2) an object does not start at the beginning of the + // region, and (3) an object does not end at the end of the prior region. + return region->partial_obj_size() == 0 && + !_mark_bitmap.is_obj_beg(bit) && + !_mark_bitmap.is_obj_end(bit - 1); +} + +inline bool +PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) { + return p >= beg_addr && p < end_addr; +} + +inline bool +PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) { + return is_in((HeapWord*)p, beg_addr, end_addr); +} + +inline MutableSpace* PSParallelCompact::space(SpaceId id) { + assert(id < last_space_id, "id out of range"); + return _space_info[id].space(); +} + +inline HeapWord* PSParallelCompact::new_top(SpaceId id) { + assert(id < last_space_id, "id out of range"); + return _space_info[id].new_top(); +} + +inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) { + assert(id < last_space_id, "id out of range"); + return _space_info[id].dense_prefix(); +} + +inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) { + assert(id < last_space_id, "id out of range"); + return _space_info[id].start_array(); +} + +#ifdef ASSERT +inline void +PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr) +{ + assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr), + "must move left or to a different space"); + assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr), + "checking alignment"); +} +#endif // ASSERT + +class MoveAndUpdateClosure: public ParMarkBitMapClosure { + public: + inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm, + ObjectStartArray* start_array, + HeapWord* destination, size_t words); + + // Accessors. + HeapWord* destination() const { return _destination; } + + // If the object will fit (size <= words_remaining()), copy it to the current + // destination, update the interior oops and the start array and return either + // full (if the closure is full) or incomplete. If the object will not fit, + // return would_overflow. + virtual IterationStatus do_addr(HeapWord* addr, size_t size); + + // Copy enough words to fill this closure, starting at source(). Interior + // oops and the start array are not updated. Return full. + IterationStatus copy_until_full(); + + // Copy enough words to fill this closure or to the end of an object, + // whichever is smaller, starting at source(). Interior oops and the start + // array are not updated. + void copy_partial_obj(); + + protected: + // Update variables to indicate that word_count words were processed. + inline void update_state(size_t word_count); + + protected: + ObjectStartArray* const _start_array; + HeapWord* _destination; // Next addr to be written. +}; + +inline +MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap, + ParCompactionManager* cm, + ObjectStartArray* start_array, + HeapWord* destination, + size_t words) : + ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array) +{ + _destination = destination; +} + +inline void MoveAndUpdateClosure::update_state(size_t words) +{ + decrement_words_remaining(words); + _source += words; + _destination += words; +} + +class UpdateOnlyClosure: public ParMarkBitMapClosure { + private: + const PSParallelCompact::SpaceId _space_id; + ObjectStartArray* const _start_array; + + public: + UpdateOnlyClosure(ParMarkBitMap* mbm, + ParCompactionManager* cm, + PSParallelCompact::SpaceId space_id); + + // Update the object. + virtual IterationStatus do_addr(HeapWord* addr, size_t words); + + inline void do_addr(HeapWord* addr); +}; + +class FillClosure: public ParMarkBitMapClosure +{ +public: + FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : + ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), + _start_array(PSParallelCompact::start_array(space_id)) + { + assert(space_id == PSParallelCompact::old_space_id, + "cannot use FillClosure in the young gen"); + } + + virtual IterationStatus do_addr(HeapWord* addr, size_t size) { + CollectedHeap::fill_with_objects(addr, size); + HeapWord* const end = addr + size; + do { + _start_array->allocate_block(addr); + addr += oop(addr)->size(); + } while (addr < end); + return ParMarkBitMap::incomplete; + } + +private: + ObjectStartArray* const _start_array; +}; + +#endif // SHARE_VM_GC_PARALLEL_PSPARALLELCOMPACT_HPP