Tue, 13 Apr 2010 13:52:10 -0700
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
Summary: Ensure a full GC that clears SoftReferences before throwing an out-of-memory
Reviewed-by: ysr, jcoomes
ysr@777 | 1 | /* |
xdono@1014 | 2 | * Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved. |
ysr@777 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
ysr@777 | 4 | * |
ysr@777 | 5 | * This code is free software; you can redistribute it and/or modify it |
ysr@777 | 6 | * under the terms of the GNU General Public License version 2 only, as |
ysr@777 | 7 | * published by the Free Software Foundation. |
ysr@777 | 8 | * |
ysr@777 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
ysr@777 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
ysr@777 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
ysr@777 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
ysr@777 | 13 | * accompanied this code). |
ysr@777 | 14 | * |
ysr@777 | 15 | * You should have received a copy of the GNU General Public License version |
ysr@777 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
ysr@777 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
ysr@777 | 18 | * |
ysr@777 | 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
ysr@777 | 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
ysr@777 | 21 | * have any questions. |
ysr@777 | 22 | * |
ysr@777 | 23 | */ |
ysr@777 | 24 | |
ysr@777 | 25 | // Sparse remembered set for a heap region (the "owning" region). Maps |
ysr@777 | 26 | // indices of other regions to short sequences of cards in the other region |
ysr@777 | 27 | // that might contain pointers into the owner region. |
ysr@777 | 28 | |
ysr@777 | 29 | // These tables only expand while they are accessed in parallel -- |
ysr@777 | 30 | // deletions may be done in single-threaded code. This allows us to allow |
ysr@777 | 31 | // unsynchronized reads/iterations, as long as expansions caused by |
ysr@777 | 32 | // insertions only enqueue old versions for deletions, but do not delete |
ysr@777 | 33 | // old versions synchronously. |
ysr@777 | 34 | |
apetrusenko@984 | 35 | class SparsePRTEntry: public CHeapObj { |
ysr@777 | 36 | public: |
ysr@777 | 37 | enum SomePublicConstants { |
iveresov@1696 | 38 | NullEntry = -1, |
iveresov@1696 | 39 | UnrollFactor = 4 |
ysr@777 | 40 | }; |
ysr@777 | 41 | private: |
johnc@1242 | 42 | RegionIdx_t _region_ind; |
johnc@1242 | 43 | int _next_index; |
iveresov@1696 | 44 | CardIdx_t _cards[1]; |
iveresov@1696 | 45 | // WARNING: Don't put any data members beyond this line. Card array has, in fact, variable length. |
iveresov@1696 | 46 | // It should always be the last data member. |
ysr@777 | 47 | public: |
iveresov@1696 | 48 | // Returns the size of the entry, used for entry allocation. |
iveresov@1696 | 49 | static size_t size() { return sizeof(SparsePRTEntry) + sizeof(CardIdx_t) * (cards_num() - 1); } |
iveresov@1696 | 50 | // Returns the size of the card array. |
iveresov@1696 | 51 | static int cards_num() { |
iveresov@1696 | 52 | // The number of cards should be a multiple of 4, because that's our current |
iveresov@1696 | 53 | // unrolling factor. |
iveresov@1696 | 54 | static const int s = MAX2<int>(G1RSetSparseRegionEntries & ~(UnrollFactor - 1), UnrollFactor); |
iveresov@1696 | 55 | return s; |
iveresov@1696 | 56 | } |
ysr@777 | 57 | |
ysr@777 | 58 | // Set the region_ind to the given value, and delete all cards. |
johnc@1242 | 59 | inline void init(RegionIdx_t region_ind); |
ysr@777 | 60 | |
johnc@1242 | 61 | RegionIdx_t r_ind() const { return _region_ind; } |
ysr@777 | 62 | bool valid_entry() const { return r_ind() >= 0; } |
johnc@1242 | 63 | void set_r_ind(RegionIdx_t rind) { _region_ind = rind; } |
ysr@777 | 64 | |
johnc@1242 | 65 | int next_index() const { return _next_index; } |
johnc@1242 | 66 | int* next_index_addr() { return &_next_index; } |
johnc@1242 | 67 | void set_next_index(int ni) { _next_index = ni; } |
ysr@777 | 68 | |
ysr@777 | 69 | // Returns "true" iff the entry contains the given card index. |
johnc@1242 | 70 | inline bool contains_card(CardIdx_t card_index) const; |
ysr@777 | 71 | |
ysr@777 | 72 | // Returns the number of non-NULL card entries. |
ysr@777 | 73 | inline int num_valid_cards() const; |
ysr@777 | 74 | |
ysr@777 | 75 | // Requires that the entry not contain the given card index. If there is |
ysr@777 | 76 | // space available, add the given card index to the entry and return |
ysr@777 | 77 | // "true"; otherwise, return "false" to indicate that the entry is full. |
ysr@777 | 78 | enum AddCardResult { |
ysr@777 | 79 | overflow, |
ysr@777 | 80 | found, |
ysr@777 | 81 | added |
ysr@777 | 82 | }; |
johnc@1242 | 83 | inline AddCardResult add_card(CardIdx_t card_index); |
ysr@777 | 84 | |
ysr@777 | 85 | // Copy the current entry's cards into "cards". |
johnc@1242 | 86 | inline void copy_cards(CardIdx_t* cards) const; |
ysr@777 | 87 | // Copy the current entry's cards into the "_card" array of "e." |
ysr@777 | 88 | inline void copy_cards(SparsePRTEntry* e) const; |
ysr@777 | 89 | |
johnc@1242 | 90 | inline CardIdx_t card(int i) const { return _cards[i]; } |
ysr@777 | 91 | }; |
ysr@777 | 92 | |
ysr@777 | 93 | |
ysr@777 | 94 | class RSHashTable : public CHeapObj { |
ysr@777 | 95 | |
ysr@777 | 96 | friend class RSHashTableIter; |
ysr@777 | 97 | |
ysr@777 | 98 | enum SomePrivateConstants { |
ysr@777 | 99 | NullEntry = -1 |
ysr@777 | 100 | }; |
ysr@777 | 101 | |
ysr@777 | 102 | size_t _capacity; |
ysr@777 | 103 | size_t _capacity_mask; |
ysr@777 | 104 | size_t _occupied_entries; |
ysr@777 | 105 | size_t _occupied_cards; |
ysr@777 | 106 | |
ysr@777 | 107 | SparsePRTEntry* _entries; |
johnc@1242 | 108 | int* _buckets; |
johnc@1242 | 109 | int _free_region; |
johnc@1242 | 110 | int _free_list; |
ysr@777 | 111 | |
ysr@777 | 112 | // Requires that the caller hold a lock preventing parallel modifying |
ysr@777 | 113 | // operations, and that the the table be less than completely full. If |
ysr@777 | 114 | // an entry for "region_ind" is already in the table, finds it and |
ysr@777 | 115 | // returns its address; otherwise returns "NULL." |
johnc@1242 | 116 | SparsePRTEntry* entry_for_region_ind(RegionIdx_t region_ind) const; |
ysr@777 | 117 | |
ysr@777 | 118 | // Requires that the caller hold a lock preventing parallel modifying |
ysr@777 | 119 | // operations, and that the the table be less than completely full. If |
ysr@777 | 120 | // an entry for "region_ind" is already in the table, finds it and |
ysr@777 | 121 | // returns its address; otherwise allocates, initializes, inserts and |
ysr@777 | 122 | // returns a new entry for "region_ind". |
johnc@1242 | 123 | SparsePRTEntry* entry_for_region_ind_create(RegionIdx_t region_ind); |
ysr@777 | 124 | |
ysr@777 | 125 | // Returns the index of the next free entry in "_entries". |
johnc@1242 | 126 | int alloc_entry(); |
ysr@777 | 127 | // Declares the entry "fi" to be free. (It must have already been |
ysr@777 | 128 | // deleted from any bucket lists. |
johnc@1242 | 129 | void free_entry(int fi); |
ysr@777 | 130 | |
ysr@777 | 131 | public: |
ysr@777 | 132 | RSHashTable(size_t capacity); |
ysr@777 | 133 | ~RSHashTable(); |
ysr@777 | 134 | |
ysr@777 | 135 | // Attempts to ensure that the given card_index in the given region is in |
ysr@777 | 136 | // the sparse table. If successful (because the card was already |
ysr@777 | 137 | // present, or because it was successfullly added) returns "true". |
ysr@777 | 138 | // Otherwise, returns "false" to indicate that the addition would |
ysr@777 | 139 | // overflow the entry for the region. The caller must transfer these |
ysr@777 | 140 | // entries to a larger-capacity representation. |
johnc@1242 | 141 | bool add_card(RegionIdx_t region_id, CardIdx_t card_index); |
ysr@777 | 142 | |
johnc@1242 | 143 | bool get_cards(RegionIdx_t region_id, CardIdx_t* cards); |
iveresov@1696 | 144 | |
johnc@1242 | 145 | bool delete_entry(RegionIdx_t region_id); |
ysr@777 | 146 | |
johnc@1242 | 147 | bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const; |
ysr@777 | 148 | |
ysr@777 | 149 | void add_entry(SparsePRTEntry* e); |
ysr@777 | 150 | |
iveresov@1696 | 151 | SparsePRTEntry* get_entry(RegionIdx_t region_id); |
iveresov@1696 | 152 | |
ysr@777 | 153 | void clear(); |
ysr@777 | 154 | |
ysr@777 | 155 | size_t capacity() const { return _capacity; } |
ysr@777 | 156 | size_t capacity_mask() const { return _capacity_mask; } |
ysr@777 | 157 | size_t occupied_entries() const { return _occupied_entries; } |
ysr@777 | 158 | size_t occupied_cards() const { return _occupied_cards; } |
ysr@777 | 159 | size_t mem_size() const; |
ysr@777 | 160 | |
iveresov@1696 | 161 | SparsePRTEntry* entry(int i) const { return (SparsePRTEntry*)((char*)_entries + SparsePRTEntry::size() * i); } |
ysr@777 | 162 | |
ysr@777 | 163 | void print(); |
ysr@777 | 164 | }; |
ysr@777 | 165 | |
johnc@1242 | 166 | // ValueObj because will be embedded in HRRS iterator. |
apetrusenko@984 | 167 | class RSHashTableIter VALUE_OBJ_CLASS_SPEC { |
johnc@1242 | 168 | int _tbl_ind; // [-1, 0.._rsht->_capacity) |
johnc@1242 | 169 | int _bl_ind; // [-1, 0.._rsht->_capacity) |
iveresov@1696 | 170 | short _card_ind; // [0..SparsePRTEntry::cards_num()) |
johnc@1242 | 171 | RSHashTable* _rsht; |
johnc@1242 | 172 | size_t _heap_bot_card_ind; |
ysr@777 | 173 | |
johnc@1242 | 174 | // If the bucket list pointed to by _bl_ind contains a card, sets |
johnc@1242 | 175 | // _bl_ind to the index of that entry, and returns the card. |
johnc@1242 | 176 | // Otherwise, returns SparseEntry::NullEntry. |
johnc@1242 | 177 | CardIdx_t find_first_card_in_list(); |
ysr@777 | 178 | |
johnc@1242 | 179 | // Computes the proper card index for the card whose offset in the |
johnc@1242 | 180 | // current region (as indicated by _bl_ind) is "ci". |
johnc@1242 | 181 | // This is subject to errors when there is iteration concurrent with |
johnc@1242 | 182 | // modification, but these errors should be benign. |
johnc@1242 | 183 | size_t compute_card_ind(CardIdx_t ci); |
ysr@777 | 184 | |
johnc@1242 | 185 | public: |
johnc@1242 | 186 | RSHashTableIter(size_t heap_bot_card_ind) : |
johnc@1242 | 187 | _tbl_ind(RSHashTable::NullEntry), |
johnc@1242 | 188 | _bl_ind(RSHashTable::NullEntry), |
iveresov@1696 | 189 | _card_ind((SparsePRTEntry::cards_num() - 1)), |
johnc@1242 | 190 | _rsht(NULL), |
johnc@1242 | 191 | _heap_bot_card_ind(heap_bot_card_ind) |
johnc@1242 | 192 | {} |
ysr@777 | 193 | |
johnc@1242 | 194 | void init(RSHashTable* rsht) { |
johnc@1242 | 195 | _rsht = rsht; |
johnc@1242 | 196 | _tbl_ind = -1; // So that first increment gets to 0. |
johnc@1242 | 197 | _bl_ind = RSHashTable::NullEntry; |
iveresov@1696 | 198 | _card_ind = (SparsePRTEntry::cards_num() - 1); |
johnc@1242 | 199 | } |
ysr@777 | 200 | |
johnc@1242 | 201 | bool has_next(size_t& card_index); |
johnc@1242 | 202 | }; |
ysr@777 | 203 | |
ysr@777 | 204 | // Concurrent accesss to a SparsePRT must be serialized by some external |
ysr@777 | 205 | // mutex. |
ysr@777 | 206 | |
ysr@777 | 207 | class SparsePRTIter; |
ysr@777 | 208 | |
apetrusenko@984 | 209 | class SparsePRT VALUE_OBJ_CLASS_SPEC { |
ysr@777 | 210 | // Iterations are done on the _cur hash table, since they only need to |
ysr@777 | 211 | // see entries visible at the start of a collection pause. |
ysr@777 | 212 | // All other operations are done using the _next hash table. |
ysr@777 | 213 | RSHashTable* _cur; |
ysr@777 | 214 | RSHashTable* _next; |
ysr@777 | 215 | |
ysr@777 | 216 | HeapRegion* _hr; |
ysr@777 | 217 | |
ysr@777 | 218 | enum SomeAdditionalPrivateConstants { |
ysr@777 | 219 | InitialCapacity = 16 |
ysr@777 | 220 | }; |
ysr@777 | 221 | |
ysr@777 | 222 | void expand(); |
ysr@777 | 223 | |
ysr@777 | 224 | bool _expanded; |
ysr@777 | 225 | |
ysr@777 | 226 | bool expanded() { return _expanded; } |
ysr@777 | 227 | void set_expanded(bool b) { _expanded = b; } |
ysr@777 | 228 | |
ysr@777 | 229 | SparsePRT* _next_expanded; |
ysr@777 | 230 | |
ysr@777 | 231 | SparsePRT* next_expanded() { return _next_expanded; } |
ysr@777 | 232 | void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; } |
ysr@777 | 233 | |
ysr@777 | 234 | static SparsePRT* _head_expanded_list; |
ysr@777 | 235 | |
ysr@777 | 236 | public: |
ysr@777 | 237 | SparsePRT(HeapRegion* hr); |
ysr@777 | 238 | |
ysr@777 | 239 | ~SparsePRT(); |
ysr@777 | 240 | |
ysr@777 | 241 | size_t occupied() const { return _next->occupied_cards(); } |
ysr@777 | 242 | size_t mem_size() const; |
ysr@777 | 243 | |
ysr@777 | 244 | // Attempts to ensure that the given card_index in the given region is in |
ysr@777 | 245 | // the sparse table. If successful (because the card was already |
ysr@777 | 246 | // present, or because it was successfullly added) returns "true". |
ysr@777 | 247 | // Otherwise, returns "false" to indicate that the addition would |
ysr@777 | 248 | // overflow the entry for the region. The caller must transfer these |
ysr@777 | 249 | // entries to a larger-capacity representation. |
johnc@1242 | 250 | bool add_card(RegionIdx_t region_id, CardIdx_t card_index); |
ysr@777 | 251 | |
ysr@777 | 252 | // If the table hold an entry for "region_ind", Copies its |
ysr@777 | 253 | // cards into "cards", which must be an array of length at least |
iveresov@1696 | 254 | // "SparePRTEntry::cards_num()", and returns "true"; otherwise, |
iveresov@1696 | 255 | // returns "false". |
johnc@1242 | 256 | bool get_cards(RegionIdx_t region_ind, CardIdx_t* cards); |
ysr@777 | 257 | |
iveresov@1696 | 258 | // Return the pointer to the entry associated with the given region. |
iveresov@1696 | 259 | SparsePRTEntry* get_entry(RegionIdx_t region_ind); |
iveresov@1696 | 260 | |
ysr@777 | 261 | // If there is an entry for "region_ind", removes it and return "true"; |
ysr@777 | 262 | // otherwise returns "false." |
johnc@1242 | 263 | bool delete_entry(RegionIdx_t region_ind); |
ysr@777 | 264 | |
ysr@777 | 265 | // Clear the table, and reinitialize to initial capacity. |
ysr@777 | 266 | void clear(); |
ysr@777 | 267 | |
ysr@777 | 268 | // Ensure that "_cur" and "_next" point to the same table. |
ysr@777 | 269 | void cleanup(); |
ysr@777 | 270 | |
ysr@777 | 271 | // Clean up all tables on the expanded list. Called single threaded. |
ysr@777 | 272 | static void cleanup_all(); |
tonyp@1052 | 273 | RSHashTable* cur() const { return _cur; } |
ysr@777 | 274 | |
ysr@777 | 275 | void init_iterator(SparsePRTIter* sprt_iter); |
ysr@777 | 276 | |
ysr@777 | 277 | static void add_to_expanded_list(SparsePRT* sprt); |
ysr@777 | 278 | static SparsePRT* get_from_expanded_list(); |
ysr@777 | 279 | |
johnc@1242 | 280 | bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const { |
ysr@777 | 281 | return _next->contains_card(region_id, card_index); |
ysr@777 | 282 | } |
ysr@777 | 283 | |
ysr@777 | 284 | #if 0 |
ysr@777 | 285 | void verify_is_cleared(); |
ysr@777 | 286 | void print(); |
ysr@777 | 287 | #endif |
ysr@777 | 288 | }; |
ysr@777 | 289 | |
ysr@777 | 290 | |
ysr@777 | 291 | class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter { |
ysr@777 | 292 | public: |
ysr@777 | 293 | SparsePRTIter(size_t heap_bot_card_ind) : |
ysr@777 | 294 | /* RSHashTable:: */RSHashTableIter(heap_bot_card_ind) |
ysr@777 | 295 | {} |
ysr@777 | 296 | |
ysr@777 | 297 | void init(const SparsePRT* sprt) { |
tonyp@1052 | 298 | RSHashTableIter::init(sprt->cur()); |
ysr@777 | 299 | } |
ysr@777 | 300 | bool has_next(size_t& card_index) { |
ysr@777 | 301 | return RSHashTableIter::has_next(card_index); |
ysr@777 | 302 | } |
ysr@777 | 303 | }; |