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view src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp @ 20280:bac98749fe00
8049831: Metadata Full GCs are not triggered when CMSClassUnloadingEnabled is turned off
Reviewed-by: brutisso, tschatzl, ehelin, jmasa, dfazunen
author | stefank |
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date | Fri, 11 Jul 2014 09:07:23 +0200 |
parents | 828056cf311f |
children | a3953c777565 |
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/* * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP #include "gc_implementation/g1/g1CodeCacheRemSet.hpp" #include "gc_implementation/g1/sparsePRT.hpp" // Remembered set for a heap region. Represent a set of "cards" that // contain pointers into the owner heap region. Cards are defined somewhat // abstractly, in terms of what the "BlockOffsetTable" in use can parse. class G1CollectedHeap; class G1BlockOffsetSharedArray; class HeapRegion; class HeapRegionRemSetIterator; class PerRegionTable; class SparsePRT; class nmethod; // Essentially a wrapper around SparsePRTCleanupTask. See // sparsePRT.hpp for more details. class HRRSCleanupTask : public SparsePRTCleanupTask { }; // The FromCardCache remembers the most recently processed card on the heap on // a per-region and per-thread basis. class FromCardCache : public AllStatic { private: // Array of card indices. Indexed by thread X and heap region to minimize // thread contention. static int** _cache; static uint _max_regions; static size_t _static_mem_size; public: enum { InvalidCard = -1 // Card value of an invalid card, i.e. a card index not otherwise used. }; static void clear(uint region_idx); // Returns true if the given card is in the cache at the given location, or // replaces the card at that location and returns false. static bool contains_or_replace(uint worker_id, uint region_idx, int card) { int card_in_cache = at(worker_id, region_idx); if (card_in_cache == card) { return true; } else { set(worker_id, region_idx, card); return false; } } static int at(uint worker_id, uint region_idx) { return _cache[worker_id][region_idx]; } static void set(uint worker_id, uint region_idx, int val) { _cache[worker_id][region_idx] = val; } static void initialize(uint n_par_rs, uint max_num_regions); static void shrink(uint new_num_regions); static void print(outputStream* out = gclog_or_tty) PRODUCT_RETURN; static size_t static_mem_size() { return _static_mem_size; } }; // The "_coarse_map" is a bitmap with one bit for each region, where set // bits indicate that the corresponding region may contain some pointer // into the owning region. // The "_fine_grain_entries" array is an open hash table of PerRegionTables // (PRTs), indicating regions for which we're keeping the RS as a set of // cards. The strategy is to cap the size of the fine-grain table, // deleting an entry and setting the corresponding coarse-grained bit when // we would overflow this cap. // We use a mixture of locking and lock-free techniques here. We allow // threads to locate PRTs without locking, but threads attempting to alter // a bucket list obtain a lock. This means that any failing attempt to // find a PRT must be retried with the lock. It might seem dangerous that // a read can find a PRT that is concurrently deleted. This is all right, // because: // // 1) We only actually free PRT's at safe points (though we reuse them at // other times). // 2) We find PRT's in an attempt to add entries. If a PRT is deleted, // it's _coarse_map bit is set, so the that we were attempting to add // is represented. If a deleted PRT is re-used, a thread adding a bit, // thinking the PRT is for a different region, does no harm. class OtherRegionsTable VALUE_OBJ_CLASS_SPEC { friend class HeapRegionRemSetIterator; G1CollectedHeap* _g1h; Mutex* _m; HeapRegion* _hr; // These are protected by "_m". BitMap _coarse_map; size_t _n_coarse_entries; static jint _n_coarsenings; PerRegionTable** _fine_grain_regions; size_t _n_fine_entries; // The fine grain remembered sets are doubly linked together using // their 'next' and 'prev' fields. // This allows fast bulk freeing of all the fine grain remembered // set entries, and fast finding of all of them without iterating // over the _fine_grain_regions table. PerRegionTable * _first_all_fine_prts; PerRegionTable * _last_all_fine_prts; // Used to sample a subset of the fine grain PRTs to determine which // PRT to evict and coarsen. size_t _fine_eviction_start; static size_t _fine_eviction_stride; static size_t _fine_eviction_sample_size; SparsePRT _sparse_table; // These are static after init. static size_t _max_fine_entries; static size_t _mod_max_fine_entries_mask; // Requires "prt" to be the first element of the bucket list appropriate // for "hr". If this list contains an entry for "hr", return it, // otherwise return "NULL". PerRegionTable* find_region_table(size_t ind, HeapRegion* hr) const; // Find, delete, and return a candidate PerRegionTable, if any exists, // adding the deleted region to the coarse bitmap. Requires the caller // to hold _m, and the fine-grain table to be full. PerRegionTable* delete_region_table(); // If a PRT for "hr" is in the bucket list indicated by "ind" (which must // be the correct index for "hr"), delete it and return true; else return // false. bool del_single_region_table(size_t ind, HeapRegion* hr); // link/add the given fine grain remembered set into the "all" list void link_to_all(PerRegionTable * prt); // unlink/remove the given fine grain remembered set into the "all" list void unlink_from_all(PerRegionTable * prt); public: OtherRegionsTable(HeapRegion* hr, Mutex* m); HeapRegion* hr() const { return _hr; } // For now. Could "expand" some tables in the future, so that this made // sense. void add_reference(OopOrNarrowOopStar from, int tid); // Removes any entries shown by the given bitmaps to contain only dead // objects. void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); size_t occupied() const; size_t occ_fine() const; size_t occ_coarse() const; size_t occ_sparse() const; static jint n_coarsenings() { return _n_coarsenings; } // Returns size in bytes. // Not const because it takes a lock. size_t mem_size() const; static size_t static_mem_size(); static size_t fl_mem_size(); bool contains_reference(OopOrNarrowOopStar from) const; bool contains_reference_locked(OopOrNarrowOopStar from) const; void clear(); // Specifically clear the from_card_cache. void clear_fcc(); void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); // Declare the heap size (in # of regions) to the OtherRegionsTable. // (Uses it to initialize from_card_cache). static void init_from_card_cache(uint max_regions); // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. // Make sure any entries for higher regions are invalid. static void shrink_from_card_cache(uint new_num_regions); static void print_from_card_cache(); }; class HeapRegionRemSet : public CHeapObj<mtGC> { friend class VMStructs; friend class HeapRegionRemSetIterator; public: enum Event { Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd }; private: G1BlockOffsetSharedArray* _bosa; G1BlockOffsetSharedArray* bosa() const { return _bosa; } // A set of code blobs (nmethods) whose code contains pointers into // the region that owns this RSet. G1CodeRootSet _code_roots; Mutex _m; OtherRegionsTable _other_regions; enum ParIterState { Unclaimed, Claimed, Complete }; volatile ParIterState _iter_state; volatile jlong _iter_claimed; // Unused unless G1RecordHRRSOops is true. static const int MaxRecorded = 1000000; static OopOrNarrowOopStar* _recorded_oops; static HeapWord** _recorded_cards; static HeapRegion** _recorded_regions; static int _n_recorded; static const int MaxRecordedEvents = 1000; static Event* _recorded_events; static int* _recorded_event_index; static int _n_recorded_events; static void print_event(outputStream* str, Event evnt); public: HeapRegionRemSet(G1BlockOffsetSharedArray* bosa, HeapRegion* hr); static uint num_par_rem_sets(); static void setup_remset_size(); HeapRegion* hr() const { return _other_regions.hr(); } size_t occupied() { MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); return occupied_locked(); } size_t occupied_locked() { return _other_regions.occupied(); } size_t occ_fine() const { return _other_regions.occ_fine(); } size_t occ_coarse() const { return _other_regions.occ_coarse(); } size_t occ_sparse() const { return _other_regions.occ_sparse(); } static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); } // Used in the sequential case. void add_reference(OopOrNarrowOopStar from) { _other_regions.add_reference(from, 0); } // Used in the parallel case. void add_reference(OopOrNarrowOopStar from, int tid) { _other_regions.add_reference(from, tid); } // Removes any entries shown by the given bitmaps to contain only dead // objects. void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm); // The region is being reclaimed; clear its remset, and any mention of // entries for this region in other remsets. void clear(); void clear_locked(); // Attempt to claim the region. Returns true iff this call caused an // atomic transition from Unclaimed to Claimed. bool claim_iter(); // Sets the iteration state to "complete". void set_iter_complete(); // Returns "true" iff the region's iteration is complete. bool iter_is_complete(); // Support for claiming blocks of cards during iteration size_t iter_claimed() const { return (size_t)_iter_claimed; } // Claim the next block of cards size_t iter_claimed_next(size_t step) { size_t current, next; do { current = iter_claimed(); next = current + step; } while (Atomic::cmpxchg((jlong)next, &_iter_claimed, (jlong)current) != (jlong)current); return current; } void reset_for_par_iteration(); bool verify_ready_for_par_iteration() { return (_iter_state == Unclaimed) && (_iter_claimed == 0); } // The actual # of bytes this hr_remset takes up. // Note also includes the strong code root set. size_t mem_size() { MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag); return _other_regions.mem_size() // This correction is necessary because the above includes the second // part. + (sizeof(HeapRegionRemSet) - sizeof(OtherRegionsTable)) + strong_code_roots_mem_size(); } // Returns the memory occupancy of all static data structures associated // with remembered sets. static size_t static_mem_size() { return OtherRegionsTable::static_mem_size() + G1CodeRootSet::free_chunks_static_mem_size(); } // Returns the memory occupancy of all free_list data structures associated // with remembered sets. static size_t fl_mem_size() { return OtherRegionsTable::fl_mem_size() + G1CodeRootSet::free_chunks_mem_size(); } bool contains_reference(OopOrNarrowOopStar from) const { return _other_regions.contains_reference(from); } // Routines for managing the list of code roots that point into // the heap region that owns this RSet. void add_strong_code_root(nmethod* nm); void remove_strong_code_root(nmethod* nm); // During a collection, migrate the successfully evacuated strong // code roots that referenced into the region that owns this RSet // to the RSets of the new regions that they now point into. // Unsuccessfully evacuated code roots are not migrated. void migrate_strong_code_roots(); // Applies blk->do_code_blob() to each of the entries in // the strong code roots list void strong_code_roots_do(CodeBlobClosure* blk) const; // Returns the number of elements in the strong code roots list size_t strong_code_roots_list_length() { return _code_roots.length(); } // Returns true if the strong code roots contains the given // nmethod. bool strong_code_roots_list_contains(nmethod* nm) { return _code_roots.contains(nm); } // Returns the amount of memory, in bytes, currently // consumed by the strong code roots. size_t strong_code_roots_mem_size(); void print() PRODUCT_RETURN; // Called during a stop-world phase to perform any deferred cleanups. static void cleanup(); // Declare the heap size (in # of regions) to the HeapRegionRemSet(s). // (Uses it to initialize from_card_cache). static void init_heap(uint max_regions) { OtherRegionsTable::init_from_card_cache(max_regions); } // Declares that only regions i s.t. 0 <= i < new_n_regs are in use. static void shrink_heap(uint new_n_regs) { OtherRegionsTable::shrink_from_card_cache(new_n_regs); } #ifndef PRODUCT static void print_from_card_cache() { OtherRegionsTable::print_from_card_cache(); } #endif static void record(HeapRegion* hr, OopOrNarrowOopStar f); static void print_recorded(); static void record_event(Event evnt); // These are wrappers for the similarly-named methods on // SparsePRT. Look at sparsePRT.hpp for more details. static void reset_for_cleanup_tasks(); void do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task); static void finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task); // Run unit tests. #ifndef PRODUCT static void test_prt(); static void test(); #endif }; class HeapRegionRemSetIterator : public StackObj { private: // The region RSet over which we are iterating. HeapRegionRemSet* _hrrs; // Local caching of HRRS fields. const BitMap* _coarse_map; G1BlockOffsetSharedArray* _bosa; G1CollectedHeap* _g1h; // The number of cards yielded since initialization. size_t _n_yielded_fine; size_t _n_yielded_coarse; size_t _n_yielded_sparse; // Indicates what granularity of table that we are currently iterating over. // We start iterating over the sparse table, progress to the fine grain // table, and then finish with the coarse table. enum IterState { Sparse, Fine, Coarse }; IterState _is; // For both Coarse and Fine remembered set iteration this contains the // first card number of the heap region we currently iterate over. size_t _cur_region_card_offset; // Current region index for the Coarse remembered set iteration. int _coarse_cur_region_index; size_t _coarse_cur_region_cur_card; bool coarse_has_next(size_t& card_index); // The PRT we are currently iterating over. PerRegionTable* _fine_cur_prt; // Card offset within the current PRT. size_t _cur_card_in_prt; // Update internal variables when switching to the given PRT. void switch_to_prt(PerRegionTable* prt); bool fine_has_next(); bool fine_has_next(size_t& card_index); // The Sparse remembered set iterator. SparsePRTIter _sparse_iter; public: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs); // If there remains one or more cards to be yielded, returns true and // sets "card_index" to one of those cards (which is then considered // yielded.) Otherwise, returns false (and leaves "card_index" // undefined.) bool has_next(size_t& card_index); size_t n_yielded_fine() { return _n_yielded_fine; } size_t n_yielded_coarse() { return _n_yielded_coarse; } size_t n_yielded_sparse() { return _n_yielded_sparse; } size_t n_yielded() { return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse(); } }; #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONREMSET_HPP