Mercurial > hg > graal-jvmci-8
view src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp @ 375:81cd571500b0
6725697: par compact - rename class ChunkData to RegionData
Reviewed-by: iveresov, tonyp
author | jcoomes |
---|---|
date | Tue, 30 Sep 2008 12:20:22 -0700 |
parents | 850fdf70db2b |
children | 0166ac265d53 |
line wrap: on
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/* * Copyright 2005-2008 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ class ParallelScavengeHeap; class PSAdaptiveSizePolicy; class PSYoungGen; class PSOldGen; class PSPermGen; class ParCompactionManager; class ParallelTaskTerminator; class PSParallelCompact; class GCTaskManager; class GCTaskQueue; class PreGCValues; class MoveAndUpdateClosure; class RefProcTaskExecutor; 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; } 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; } private: MutableSpace* _space; HeapWord* _new_top; HeapWord* _min_dense_prefix; HeapWord* _dense_prefix; ObjectStartArray* _start_array; }; 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 BlockOffsetMask; static const size_t BlockMask; static const size_t BlocksPerRegion; 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; // 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_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; #ifdef ASSERT // 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 worker's 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 in the Block. This amount of live data will // include any object extending into the block. The first block in // a region does not include any partial object extending into the // the region. // // The offset also encodes the // 'parity' of the first 1 bit in the Block: a positive offset means the // first 1 bit marks the start of an object, a negative offset means the first // 1 bit marks the end of an object. class BlockData { public: typedef short int blk_ofs_t; blk_ofs_t offset() const { return _offset >= 0 ? _offset : -_offset; } blk_ofs_t raw_offset() const { return _offset; } void set_first_is_start_bit(bool v) { _first_is_start_bit = v; } #if 0 // The need for this method was anticipated but it is // never actually used. Do not include it for now. If // it is needed, consider the problem of what is passed // as "v". To avoid warning errors the method set_start_bit_offset() // was changed to take a size_t as the parameter and to do the // check for the possible overflow. Doing the cast in these // methods better limits the potential problems because of // the size of the field to this class. void set_raw_offset(blk_ofs_t v) { _offset = v; } #endif void set_start_bit_offset(size_t val) { assert(val >= 0, "sanity"); _offset = (blk_ofs_t) val; assert(val == (size_t) _offset, "Value is too large"); _first_is_start_bit = true; } void set_end_bit_offset(size_t val) { assert(val >= 0, "sanity"); _offset = (blk_ofs_t) val; assert(val == (size_t) _offset, "Value is too large"); _offset = - _offset; _first_is_start_bit = false; } bool first_is_start_bit() { assert(_set_phase > 0, "Not initialized"); return _first_is_start_bit; } bool first_is_end_bit() { assert(_set_phase > 0, "Not initialized"); return !_first_is_start_bit; } private: blk_ofs_t _offset; // This is temporary until the mark_bitmap is separated into // a start bit array and an end bit array. bool _first_is_start_bit; #ifdef ASSERT short _set_phase; static short _cur_phase; public: static void set_cur_phase(short v) { _cur_phase = v; } #endif }; public: ParallelCompactData(); bool initialize(MemRegion covered_region); size_t region_count() const { return _region_count; } // 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; // Returns true if the given address is contained within the region bool region_contains(size_t region_index, HeapWord* addr); size_t block_count() const { return _block_count; } inline BlockData* block(size_t n) const; // Returns true if the given block is in the given region. static bool region_contains_block(size_t region_index, size_t block_index); 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); bool summarize(HeapWord* target_beg, HeapWord* target_end, HeapWord* source_beg, HeapWord* source_end, HeapWord** target_next, HeapWord** source_next = 0); 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; // Return the address one past the end of the partial object. HeapWord* partial_obj_end(size_t region_idx) const; // Return the new location of the object p after the // the compaction. HeapWord* calc_new_pointer(HeapWord* addr); // Same as calc_new_pointer() using blocks. HeapWord* block_calc_new_pointer(HeapWord* addr); // Same as calc_new_pointer() using regions. HeapWord* region_calc_new_pointer(HeapWord* addr); HeapWord* calc_new_pointer(oop p) { return calc_new_pointer((HeapWord*) p); } // Return the updated address for the given klass klassOop calc_new_klass(klassOop); // Given a block returns true if the partial object for the // corresponding region ends in the block. Returns false, otherwise // If there is no partial object, returns false. bool partial_obj_ends_in_block(size_t block_index); // Returns the block index for the block static size_t block_idx(BlockData* block); #ifdef ASSERT void verify_clear(const PSVirtualSpace* vspace); void verify_clear(); #endif // #ifdef ASSERT private: bool initialize_block_data(size_t region_size); 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; 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 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 pointer_delta(addr, _region_start) & BlockOffsetMask; } 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); } // 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; } // Closure for updating the block data during the summary phase. class BitBlockUpdateClosure: public ParMarkBitMapClosure { // ParallelCompactData::BlockData::blk_ofs_t _live_data_left; size_t _live_data_left; size_t _cur_block; HeapWord* _region_start; HeapWord* _region_end; size_t _region_index; public: BitBlockUpdateClosure(ParMarkBitMap* mbm, ParCompactionManager* cm, size_t region_index); size_t cur_block() { return _cur_block; } size_t region_index() { return _region_index; } size_t live_data_left() { return _live_data_left; } // Returns true the first bit in the current block (cur_block) is // a start bit. // Returns true if the current block is within the region for the closure; bool region_contains_cur_block(); // Set the region index and related region values for // a new region. void reset_region(size_t region_index); virtual IterationStatus do_addr(HeapWord* addr, size_t 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 quantites 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 { perm_space_id, 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 void do_object(oop p); virtual bool do_object_b(oop p); }; class KeepAliveClosure: public OopClosure { private: ParCompactionManager* _compaction_manager; protected: template <class T> inline void do_oop_work(T* p); public: KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { } virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); }; // Current unused class FollowRootClosure: public OopsInGenClosure { private: ParCompactionManager* _compaction_manager; public: FollowRootClosure(ParCompactionManager* cm) : _compaction_manager(cm) { } virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); virtual const bool do_nmethods() const { return true; } }; class FollowStackClosure: public VoidClosure { private: ParCompactionManager* _compaction_manager; public: FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { } virtual void do_void(); }; class AdjustPointerClosure: public OopsInGenClosure { private: bool _is_root; public: AdjustPointerClosure(bool is_root) : _is_root(is_root) { } virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); }; // Closure for verifying update of pointers. Does not // have any side effects. class VerifyUpdateClosure: public ParMarkBitMapClosure { const MutableSpace* _space; // Is this ever used? public: VerifyUpdateClosure(ParCompactionManager* cm, const MutableSpace* sp) : ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), _space(sp) { } virtual IterationStatus do_addr(HeapWord* addr, size_t words); const MutableSpace* space() { return _space; } }; // Closure for updating objects altered for debug checking class ResetObjectsClosure: public ParMarkBitMapClosure { public: ResetObjectsClosure(ParCompactionManager* cm): ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm) { } virtual IterationStatus do_addr(HeapWord* addr, size_t words); }; friend class KeepAliveClosure; friend class FollowStackClosure; friend class AdjustPointerClosure; friend class FollowRootClosure; friend class instanceKlassKlass; friend class RefProcTaskProxy; private: 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_root_pointer_closure; static AdjustPointerClosure _adjust_pointer_closure; // Reference processing (used in ...follow_contents) static ReferenceProcessor* _ref_processor; // Updated location of intArrayKlassObj. static klassOop _updated_int_array_klass_obj; // 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 private: // Closure accessors static OopClosure* adjust_pointer_closure() { return (OopClosure*)&_adjust_pointer_closure; } static OopClosure* adjust_root_pointer_closure() { return (OopClosure*)&_adjust_root_pointer_closure; } static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; } 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); static void follow_stack(ParCompactionManager* cm); static void follow_weak_klass_links(ParCompactionManager* cm); template <class T> static inline void adjust_pointer(T* p, bool is_root); static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); } template <class T> static inline void follow_root(ParCompactionManager* cm, T* p); // 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); static void summarize_spaces_quick(); static void summarize_space(SpaceId id, bool maximum_compaction); static void summary_phase(ParCompactionManager* cm, bool maximum_compaction); static bool block_first_offset(size_t block_index, idx_t* block_offset_ptr); // Fill in the BlockData static void summarize_blocks(ParCompactionManager* cm, SpaceId first_compaction_space_id); // The space that is compacted after space_id. static SpaceId next_compaction_space_id(SpaceId space_id); // Adjust addresses in roots. Does not adjust addresses in heap. static void adjust_roots(); // Serial code executed in preparation for the compaction phase. static void compact_prologue(); // 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); // For debugging only - compacts the old gen serially static void compact_serial(ParCompactionManager* cm); // 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(); protected: #ifdef VALIDATE_MARK_SWEEP static GrowableArray<void*>* _root_refs_stack; static GrowableArray<oop> * _live_oops; static GrowableArray<oop> * _live_oops_moved_to; static GrowableArray<size_t>* _live_oops_size; static size_t _live_oops_index; static size_t _live_oops_index_at_perm; static GrowableArray<void*>* _other_refs_stack; static GrowableArray<void*>* _adjusted_pointers; static bool _pointer_tracking; static bool _root_tracking; // The following arrays are saved since the time of the last GC and // assist in tracking down problems where someone has done an errant // store into the heap, usually to an oop that wasn't properly // handleized across a GC. If we crash or otherwise fail before the // next GC, we can query these arrays to find out the object we had // intended to do the store to (assuming it is still alive) and the // offset within that object. Covered under RecordMarkSweepCompaction. static GrowableArray<HeapWord*> * _cur_gc_live_oops; static GrowableArray<HeapWord*> * _cur_gc_live_oops_moved_to; static GrowableArray<size_t>* _cur_gc_live_oops_size; static GrowableArray<HeapWord*> * _last_gc_live_oops; static GrowableArray<HeapWord*> * _last_gc_live_oops_moved_to; static GrowableArray<size_t>* _last_gc_live_oops_size; #endif public: class MarkAndPushClosure: public OopClosure { private: ParCompactionManager* _compaction_manager; public: MarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { } virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); virtual const bool do_nmethods() const { return true; } }; PSParallelCompact(); // Convenient accessor for Universe::heap(). static ParallelScavengeHeap* gc_heap() { return (ParallelScavengeHeap*)Universe::heap(); } static void invoke(bool maximum_heap_compaction); static void 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(); // 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(); static klassOop updated_int_array_klass_obj() { return _updated_int_array_klass_obj; } // Marking support static inline bool mark_obj(oop obj); // Check mark and maybe push on marking stack template <class T> static inline void mark_and_push(ParCompactionManager* cm, 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); // Return true if the klass should be updated. static inline bool should_update_klass(klassOop k); // 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, 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))). static void decrement_destination_counts(ParCompactionManager* cm, 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); } // Update the deferred objects in the space. static void update_deferred_objects(ParCompactionManager* cm, SpaceId id); // Mark pointer and follow contents. template <class T> static inline void mark_and_follow(ParCompactionManager* cm, T* p); static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; } static ParallelCompactData& summary_data() { return _summary_data; } static inline void adjust_pointer(oop* p) { adjust_pointer(p, false); } static inline void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); } template <class T> static inline void adjust_pointer(T* p, HeapWord* beg_addr, HeapWord* end_addr); // Reference Processing static ReferenceProcessor* const ref_processor() { return _ref_processor; } // 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(); #ifdef VALIDATE_MARK_SWEEP static void track_adjusted_pointer(void* p, bool isroot); static void check_adjust_pointer(void* p); static void track_interior_pointers(oop obj); static void check_interior_pointers(); static void reset_live_oop_tracking(bool at_perm); static void register_live_oop(oop p, size_t size); static void validate_live_oop(oop p, size_t size); static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top); static void compaction_complete(); // Querying operation of RecordMarkSweepCompaction results. // Finds and prints the current base oop and offset for a word // within an oop that was live during the last GC. Helpful for // tracking down heap stomps. static void print_new_location_of_heap_address(HeapWord* q); #endif // #ifdef VALIDATE_MARK_SWEEP // Call backs for class unloading // Update subklass/sibling/implementor links at end of marking. static void revisit_weak_klass_link(ParCompactionManager* cm, Klass* k); #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); #endif // #ifndef PRODUCT #ifdef ASSERT // 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; } } template <class T> inline void PSParallelCompact::follow_root(ParCompactionManager* cm, T* p) { assert(!Universe::heap()->is_in_reserved(p), "roots shouldn't be things within the heap"); #ifdef VALIDATE_MARK_SWEEP if (ValidateMarkSweep) { guarantee(!_root_refs_stack->contains(p), "should only be in here once"); _root_refs_stack->push(p); } #endif T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); if (mark_bitmap()->is_unmarked(obj)) { if (mark_obj(obj)) { obj->follow_contents(cm); } } } follow_stack(cm); } template <class T> inline void PSParallelCompact::mark_and_follow(ParCompactionManager* cm, T* p) { T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); if (mark_bitmap()->is_unmarked(obj)) { if (mark_obj(obj)) { obj->follow_contents(cm); } } } } template <class T> inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, T* p) { T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); if (mark_bitmap()->is_unmarked(obj)) { if (mark_obj(obj)) { // This thread marked the object and owns the subsequent processing of it. cm->save_for_scanning(obj); } } } } template <class T> inline void PSParallelCompact::adjust_pointer(T* p, bool isroot) { T heap_oop = oopDesc::load_heap_oop(p); if (!oopDesc::is_null(heap_oop)) { oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); oop new_obj = (oop)summary_data().calc_new_pointer(obj); assert(new_obj != NULL || // is forwarding ptr? obj->is_shared(), // never forwarded? "should be forwarded"); // Just always do the update unconditionally? if (new_obj != NULL) { assert(Universe::heap()->is_in_reserved(new_obj), "should be in object space"); oopDesc::encode_store_heap_oop_not_null(p, new_obj); } } VALIDATE_MARK_SWEEP_ONLY(track_adjusted_pointer(p, isroot)); } template <class T> inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) { #ifdef VALIDATE_MARK_SWEEP if (ValidateMarkSweep) { if (!Universe::heap()->is_in_reserved(p)) { _root_refs_stack->push(p); } else { _other_refs_stack->push(p); } } #endif mark_and_push(_compaction_manager, p); } 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(); } inline bool PSParallelCompact::should_update_klass(klassOop k) { return ((HeapWord*) k) >= dense_prefix(perm_space_id); } template <class T> inline void PSParallelCompact::adjust_pointer(T* p, HeapWord* beg_addr, HeapWord* end_addr) { if (is_in((HeapWord*)p, beg_addr, end_addr)) { adjust_pointer(p); } } 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); }; inline void UpdateOnlyClosure::do_addr(HeapWord* addr) { _start_array->allocate_block(addr); oop(addr)->update_contents(compaction_manager()); } class FillClosure: public ParMarkBitMapClosure { public: FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) : ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), _space_id(space_id), _start_array(PSParallelCompact::start_array(space_id)) { assert(_space_id == PSParallelCompact::perm_space_id || _space_id == PSParallelCompact::old_space_id, "cannot use FillClosure in the young gen"); assert(bitmap() != NULL, "need a bitmap"); assert(_start_array != NULL, "need a start array"); } void fill_region(HeapWord* addr, size_t size) { MemRegion region(addr, size); SharedHeap::fill_region_with_object(region); _start_array->allocate_block(addr); } virtual IterationStatus do_addr(HeapWord* addr, size_t size) { fill_region(addr, size); return ParMarkBitMap::incomplete; } private: const PSParallelCompact::SpaceId _space_id; ObjectStartArray* const _start_array; };