Thu, 11 Dec 2008 12:05:08 -0800
6578152: fill_region_with_object has usability and safety issues
Reviewed-by: apetrusenko, ysr
duke@435 | 1 | /* |
xdono@631 | 2 | * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved. |
duke@435 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@435 | 4 | * |
duke@435 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@435 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@435 | 7 | * published by the Free Software Foundation. |
duke@435 | 8 | * |
duke@435 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@435 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@435 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@435 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@435 | 13 | * accompanied this code). |
duke@435 | 14 | * |
duke@435 | 15 | * You should have received a copy of the GNU General Public License version |
duke@435 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@435 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@435 | 18 | * |
duke@435 | 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
duke@435 | 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
duke@435 | 21 | * have any questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
duke@435 | 25 | #include "incls/_precompiled.incl" |
duke@435 | 26 | #include "incls/_genMarkSweep.cpp.incl" |
duke@435 | 27 | |
duke@435 | 28 | void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp, |
duke@435 | 29 | bool clear_all_softrefs) { |
duke@435 | 30 | assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); |
duke@435 | 31 | |
duke@435 | 32 | // hook up weak ref data so it can be used during Mark-Sweep |
duke@435 | 33 | assert(ref_processor() == NULL, "no stomping"); |
ysr@888 | 34 | assert(rp != NULL, "should be non-NULL"); |
duke@435 | 35 | _ref_processor = rp; |
ysr@892 | 36 | rp->setup_policy(clear_all_softrefs); |
duke@435 | 37 | |
duke@435 | 38 | TraceTime t1("Full GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); |
duke@435 | 39 | |
duke@435 | 40 | // When collecting the permanent generation methodOops may be moving, |
duke@435 | 41 | // so we either have to flush all bcp data or convert it into bci. |
duke@435 | 42 | CodeCache::gc_prologue(); |
duke@435 | 43 | Threads::gc_prologue(); |
duke@435 | 44 | |
duke@435 | 45 | // Increment the invocation count for the permanent generation, since it is |
duke@435 | 46 | // implicitly collected whenever we do a full mark sweep collection. |
duke@435 | 47 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 48 | gch->perm_gen()->stat_record()->invocations++; |
duke@435 | 49 | |
duke@435 | 50 | // Capture heap size before collection for printing. |
duke@435 | 51 | size_t gch_prev_used = gch->used(); |
duke@435 | 52 | |
duke@435 | 53 | // Some of the card table updates below assume that the perm gen is |
duke@435 | 54 | // also being collected. |
duke@435 | 55 | assert(level == gch->n_gens() - 1, |
duke@435 | 56 | "All generations are being collected, ergo perm gen too."); |
duke@435 | 57 | |
duke@435 | 58 | // Capture used regions for each generation that will be |
duke@435 | 59 | // subject to collection, so that card table adjustments can |
duke@435 | 60 | // be made intelligently (see clear / invalidate further below). |
duke@435 | 61 | gch->save_used_regions(level, true /* perm */); |
duke@435 | 62 | |
duke@435 | 63 | allocate_stacks(); |
duke@435 | 64 | |
duke@435 | 65 | mark_sweep_phase1(level, clear_all_softrefs); |
duke@435 | 66 | |
duke@435 | 67 | mark_sweep_phase2(); |
duke@435 | 68 | |
duke@435 | 69 | // Don't add any more derived pointers during phase3 |
duke@435 | 70 | COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity")); |
duke@435 | 71 | COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); |
duke@435 | 72 | |
duke@435 | 73 | mark_sweep_phase3(level); |
duke@435 | 74 | |
duke@435 | 75 | VALIDATE_MARK_SWEEP_ONLY( |
duke@435 | 76 | if (ValidateMarkSweep) { |
coleenp@548 | 77 | guarantee(_root_refs_stack->length() == 0, "should be empty by now"); |
duke@435 | 78 | } |
duke@435 | 79 | ) |
duke@435 | 80 | |
duke@435 | 81 | mark_sweep_phase4(); |
duke@435 | 82 | |
duke@435 | 83 | VALIDATE_MARK_SWEEP_ONLY( |
duke@435 | 84 | if (ValidateMarkSweep) { |
duke@435 | 85 | guarantee(_live_oops->length() == _live_oops_moved_to->length(), |
duke@435 | 86 | "should be the same size"); |
duke@435 | 87 | } |
duke@435 | 88 | ) |
duke@435 | 89 | |
duke@435 | 90 | restore_marks(); |
duke@435 | 91 | |
duke@435 | 92 | // Set saved marks for allocation profiler (and other things? -- dld) |
duke@435 | 93 | // (Should this be in general part?) |
duke@435 | 94 | gch->save_marks(); |
duke@435 | 95 | |
duke@435 | 96 | deallocate_stacks(); |
duke@435 | 97 | |
duke@435 | 98 | // If compaction completely evacuated all generations younger than this |
duke@435 | 99 | // one, then we can clear the card table. Otherwise, we must invalidate |
duke@435 | 100 | // it (consider all cards dirty). In the future, we might consider doing |
duke@435 | 101 | // compaction within generations only, and doing card-table sliding. |
duke@435 | 102 | bool all_empty = true; |
duke@435 | 103 | for (int i = 0; all_empty && i < level; i++) { |
duke@435 | 104 | Generation* g = gch->get_gen(i); |
duke@435 | 105 | all_empty = all_empty && gch->get_gen(i)->used() == 0; |
duke@435 | 106 | } |
duke@435 | 107 | GenRemSet* rs = gch->rem_set(); |
duke@435 | 108 | // Clear/invalidate below make use of the "prev_used_regions" saved earlier. |
duke@435 | 109 | if (all_empty) { |
duke@435 | 110 | // We've evacuated all generations below us. |
duke@435 | 111 | Generation* g = gch->get_gen(level); |
duke@435 | 112 | rs->clear_into_younger(g, true /* perm */); |
duke@435 | 113 | } else { |
duke@435 | 114 | // Invalidate the cards corresponding to the currently used |
duke@435 | 115 | // region and clear those corresponding to the evacuated region |
duke@435 | 116 | // of all generations just collected (i.e. level and younger). |
duke@435 | 117 | rs->invalidate_or_clear(gch->get_gen(level), |
duke@435 | 118 | true /* younger */, |
duke@435 | 119 | true /* perm */); |
duke@435 | 120 | } |
duke@435 | 121 | |
duke@435 | 122 | Threads::gc_epilogue(); |
duke@435 | 123 | CodeCache::gc_epilogue(); |
duke@435 | 124 | |
duke@435 | 125 | if (PrintGC && !PrintGCDetails) { |
duke@435 | 126 | gch->print_heap_change(gch_prev_used); |
duke@435 | 127 | } |
duke@435 | 128 | |
duke@435 | 129 | // refs processing: clean slate |
duke@435 | 130 | _ref_processor = NULL; |
duke@435 | 131 | |
duke@435 | 132 | // Update heap occupancy information which is used as |
duke@435 | 133 | // input to soft ref clearing policy at the next gc. |
duke@435 | 134 | Universe::update_heap_info_at_gc(); |
duke@435 | 135 | |
duke@435 | 136 | // Update time of last gc for all generations we collected |
duke@435 | 137 | // (which curently is all the generations in the heap). |
duke@435 | 138 | gch->update_time_of_last_gc(os::javaTimeMillis()); |
duke@435 | 139 | } |
duke@435 | 140 | |
duke@435 | 141 | void GenMarkSweep::allocate_stacks() { |
duke@435 | 142 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 143 | // Scratch request on behalf of oldest generation; will do no |
duke@435 | 144 | // allocation. |
duke@435 | 145 | ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0); |
duke@435 | 146 | |
duke@435 | 147 | // $$$ To cut a corner, we'll only use the first scratch block, and then |
duke@435 | 148 | // revert to malloc. |
duke@435 | 149 | if (scratch != NULL) { |
duke@435 | 150 | _preserved_count_max = |
duke@435 | 151 | scratch->num_words * HeapWordSize / sizeof(PreservedMark); |
duke@435 | 152 | } else { |
duke@435 | 153 | _preserved_count_max = 0; |
duke@435 | 154 | } |
duke@435 | 155 | |
duke@435 | 156 | _preserved_marks = (PreservedMark*)scratch; |
duke@435 | 157 | _preserved_count = 0; |
duke@435 | 158 | _preserved_mark_stack = NULL; |
duke@435 | 159 | _preserved_oop_stack = NULL; |
duke@435 | 160 | |
duke@435 | 161 | _marking_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(4000, true); |
duke@435 | 162 | |
duke@435 | 163 | int size = SystemDictionary::number_of_classes() * 2; |
duke@435 | 164 | _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true); |
duke@435 | 165 | |
duke@435 | 166 | #ifdef VALIDATE_MARK_SWEEP |
duke@435 | 167 | if (ValidateMarkSweep) { |
coleenp@548 | 168 | _root_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
coleenp@548 | 169 | _other_refs_stack = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
coleenp@548 | 170 | _adjusted_pointers = new (ResourceObj::C_HEAP) GrowableArray<void*>(100, true); |
duke@435 | 171 | _live_oops = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); |
duke@435 | 172 | _live_oops_moved_to = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true); |
duke@435 | 173 | _live_oops_size = new (ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); |
duke@435 | 174 | } |
duke@435 | 175 | if (RecordMarkSweepCompaction) { |
duke@435 | 176 | if (_cur_gc_live_oops == NULL) { |
duke@435 | 177 | _cur_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
duke@435 | 178 | _cur_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
duke@435 | 179 | _cur_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); |
duke@435 | 180 | _last_gc_live_oops = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
duke@435 | 181 | _last_gc_live_oops_moved_to = new(ResourceObj::C_HEAP) GrowableArray<HeapWord*>(100, true); |
duke@435 | 182 | _last_gc_live_oops_size = new(ResourceObj::C_HEAP) GrowableArray<size_t>(100, true); |
duke@435 | 183 | } else { |
duke@435 | 184 | _cur_gc_live_oops->clear(); |
duke@435 | 185 | _cur_gc_live_oops_moved_to->clear(); |
duke@435 | 186 | _cur_gc_live_oops_size->clear(); |
duke@435 | 187 | } |
duke@435 | 188 | } |
duke@435 | 189 | #endif |
duke@435 | 190 | } |
duke@435 | 191 | |
duke@435 | 192 | |
duke@435 | 193 | void GenMarkSweep::deallocate_stacks() { |
jmasa@698 | 194 | |
tonyp@791 | 195 | if (!UseG1GC) { |
tonyp@791 | 196 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
tonyp@791 | 197 | gch->release_scratch(); |
tonyp@791 | 198 | } |
jmasa@698 | 199 | |
duke@435 | 200 | if (_preserved_oop_stack) { |
duke@435 | 201 | delete _preserved_mark_stack; |
duke@435 | 202 | _preserved_mark_stack = NULL; |
duke@435 | 203 | delete _preserved_oop_stack; |
duke@435 | 204 | _preserved_oop_stack = NULL; |
duke@435 | 205 | } |
duke@435 | 206 | |
duke@435 | 207 | delete _marking_stack; |
duke@435 | 208 | delete _revisit_klass_stack; |
duke@435 | 209 | |
duke@435 | 210 | #ifdef VALIDATE_MARK_SWEEP |
duke@435 | 211 | if (ValidateMarkSweep) { |
duke@435 | 212 | delete _root_refs_stack; |
duke@435 | 213 | delete _other_refs_stack; |
duke@435 | 214 | delete _adjusted_pointers; |
duke@435 | 215 | delete _live_oops; |
duke@435 | 216 | delete _live_oops_size; |
duke@435 | 217 | delete _live_oops_moved_to; |
duke@435 | 218 | _live_oops_index = 0; |
duke@435 | 219 | _live_oops_index_at_perm = 0; |
duke@435 | 220 | } |
duke@435 | 221 | #endif |
duke@435 | 222 | } |
duke@435 | 223 | |
duke@435 | 224 | void GenMarkSweep::mark_sweep_phase1(int level, |
duke@435 | 225 | bool clear_all_softrefs) { |
duke@435 | 226 | // Recursively traverse all live objects and mark them |
duke@435 | 227 | EventMark m("1 mark object"); |
duke@435 | 228 | TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty); |
duke@435 | 229 | trace(" 1"); |
duke@435 | 230 | |
duke@435 | 231 | VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
duke@435 | 232 | |
duke@435 | 233 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 234 | |
duke@435 | 235 | // Because follow_root_closure is created statically, cannot |
duke@435 | 236 | // use OopsInGenClosure constructor which takes a generation, |
duke@435 | 237 | // as the Universe has not been created when the static constructors |
duke@435 | 238 | // are run. |
duke@435 | 239 | follow_root_closure.set_orig_generation(gch->get_gen(level)); |
duke@435 | 240 | |
duke@435 | 241 | gch->gen_process_strong_roots(level, |
duke@435 | 242 | false, // Younger gens are not roots. |
duke@435 | 243 | true, // Collecting permanent generation. |
duke@435 | 244 | SharedHeap::SO_SystemClasses, |
duke@435 | 245 | &follow_root_closure, &follow_root_closure); |
duke@435 | 246 | |
duke@435 | 247 | // Process reference objects found during marking |
duke@435 | 248 | { |
ysr@892 | 249 | ref_processor()->setup_policy(clear_all_softrefs); |
duke@435 | 250 | ref_processor()->process_discovered_references( |
ysr@888 | 251 | &is_alive, &keep_alive, &follow_stack_closure, NULL); |
duke@435 | 252 | } |
duke@435 | 253 | |
duke@435 | 254 | // Follow system dictionary roots and unload classes |
duke@435 | 255 | bool purged_class = SystemDictionary::do_unloading(&is_alive); |
duke@435 | 256 | |
duke@435 | 257 | // Follow code cache roots |
duke@435 | 258 | CodeCache::do_unloading(&is_alive, &keep_alive, purged_class); |
duke@435 | 259 | follow_stack(); // Flush marking stack |
duke@435 | 260 | |
duke@435 | 261 | // Update subklass/sibling/implementor links of live klasses |
duke@435 | 262 | follow_weak_klass_links(); |
duke@435 | 263 | assert(_marking_stack->is_empty(), "just drained"); |
duke@435 | 264 | |
duke@435 | 265 | // Visit symbol and interned string tables and delete unmarked oops |
duke@435 | 266 | SymbolTable::unlink(&is_alive); |
duke@435 | 267 | StringTable::unlink(&is_alive); |
duke@435 | 268 | |
duke@435 | 269 | assert(_marking_stack->is_empty(), "stack should be empty by now"); |
duke@435 | 270 | } |
duke@435 | 271 | |
duke@435 | 272 | |
duke@435 | 273 | void GenMarkSweep::mark_sweep_phase2() { |
duke@435 | 274 | // Now all live objects are marked, compute the new object addresses. |
duke@435 | 275 | |
duke@435 | 276 | // It is imperative that we traverse perm_gen LAST. If dead space is |
duke@435 | 277 | // allowed a range of dead object may get overwritten by a dead int |
duke@435 | 278 | // array. If perm_gen is not traversed last a klassOop may get |
duke@435 | 279 | // overwritten. This is fine since it is dead, but if the class has dead |
duke@435 | 280 | // instances we have to skip them, and in order to find their size we |
duke@435 | 281 | // need the klassOop! |
duke@435 | 282 | // |
duke@435 | 283 | // It is not required that we traverse spaces in the same order in |
duke@435 | 284 | // phase2, phase3 and phase4, but the ValidateMarkSweep live oops |
duke@435 | 285 | // tracking expects us to do so. See comment under phase4. |
duke@435 | 286 | |
duke@435 | 287 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 288 | Generation* pg = gch->perm_gen(); |
duke@435 | 289 | |
duke@435 | 290 | EventMark m("2 compute new addresses"); |
duke@435 | 291 | TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty); |
duke@435 | 292 | trace("2"); |
duke@435 | 293 | |
duke@435 | 294 | VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
duke@435 | 295 | |
duke@435 | 296 | gch->prepare_for_compaction(); |
duke@435 | 297 | |
duke@435 | 298 | VALIDATE_MARK_SWEEP_ONLY(_live_oops_index_at_perm = _live_oops_index); |
duke@435 | 299 | CompactPoint perm_cp(pg, NULL, NULL); |
duke@435 | 300 | pg->prepare_for_compaction(&perm_cp); |
duke@435 | 301 | } |
duke@435 | 302 | |
duke@435 | 303 | class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure { |
duke@435 | 304 | public: |
duke@435 | 305 | void do_generation(Generation* gen) { |
duke@435 | 306 | gen->adjust_pointers(); |
duke@435 | 307 | } |
duke@435 | 308 | }; |
duke@435 | 309 | |
duke@435 | 310 | void GenMarkSweep::mark_sweep_phase3(int level) { |
duke@435 | 311 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 312 | Generation* pg = gch->perm_gen(); |
duke@435 | 313 | |
duke@435 | 314 | // Adjust the pointers to reflect the new locations |
duke@435 | 315 | EventMark m("3 adjust pointers"); |
duke@435 | 316 | TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty); |
duke@435 | 317 | trace("3"); |
duke@435 | 318 | |
duke@435 | 319 | VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
duke@435 | 320 | |
duke@435 | 321 | // Needs to be done before the system dictionary is adjusted. |
duke@435 | 322 | pg->pre_adjust_pointers(); |
duke@435 | 323 | |
duke@435 | 324 | // Because the two closures below are created statically, cannot |
duke@435 | 325 | // use OopsInGenClosure constructor which takes a generation, |
duke@435 | 326 | // as the Universe has not been created when the static constructors |
duke@435 | 327 | // are run. |
duke@435 | 328 | adjust_root_pointer_closure.set_orig_generation(gch->get_gen(level)); |
duke@435 | 329 | adjust_pointer_closure.set_orig_generation(gch->get_gen(level)); |
duke@435 | 330 | |
duke@435 | 331 | gch->gen_process_strong_roots(level, |
duke@435 | 332 | false, // Younger gens are not roots. |
duke@435 | 333 | true, // Collecting permanent generation. |
duke@435 | 334 | SharedHeap::SO_AllClasses, |
duke@435 | 335 | &adjust_root_pointer_closure, |
duke@435 | 336 | &adjust_root_pointer_closure); |
duke@435 | 337 | |
duke@435 | 338 | // Now adjust pointers in remaining weak roots. (All of which should |
duke@435 | 339 | // have been cleared if they pointed to non-surviving objects.) |
duke@435 | 340 | gch->gen_process_weak_roots(&adjust_root_pointer_closure, |
duke@435 | 341 | &adjust_pointer_closure); |
duke@435 | 342 | |
duke@435 | 343 | adjust_marks(); |
duke@435 | 344 | GenAdjustPointersClosure blk; |
duke@435 | 345 | gch->generation_iterate(&blk, true); |
duke@435 | 346 | pg->adjust_pointers(); |
duke@435 | 347 | } |
duke@435 | 348 | |
duke@435 | 349 | class GenCompactClosure: public GenCollectedHeap::GenClosure { |
duke@435 | 350 | public: |
duke@435 | 351 | void do_generation(Generation* gen) { |
duke@435 | 352 | gen->compact(); |
duke@435 | 353 | } |
duke@435 | 354 | }; |
duke@435 | 355 | |
duke@435 | 356 | void GenMarkSweep::mark_sweep_phase4() { |
duke@435 | 357 | // All pointers are now adjusted, move objects accordingly |
duke@435 | 358 | |
duke@435 | 359 | // It is imperative that we traverse perm_gen first in phase4. All |
duke@435 | 360 | // classes must be allocated earlier than their instances, and traversing |
duke@435 | 361 | // perm_gen first makes sure that all klassOops have moved to their new |
duke@435 | 362 | // location before any instance does a dispatch through it's klass! |
duke@435 | 363 | |
duke@435 | 364 | // The ValidateMarkSweep live oops tracking expects us to traverse spaces |
duke@435 | 365 | // in the same order in phase2, phase3 and phase4. We don't quite do that |
duke@435 | 366 | // here (perm_gen first rather than last), so we tell the validate code |
duke@435 | 367 | // to use a higher index (saved from phase2) when verifying perm_gen. |
duke@435 | 368 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 369 | Generation* pg = gch->perm_gen(); |
duke@435 | 370 | |
duke@435 | 371 | EventMark m("4 compact heap"); |
duke@435 | 372 | TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty); |
duke@435 | 373 | trace("4"); |
duke@435 | 374 | |
duke@435 | 375 | VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(true)); |
duke@435 | 376 | |
duke@435 | 377 | pg->compact(); |
duke@435 | 378 | |
duke@435 | 379 | VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false)); |
duke@435 | 380 | |
duke@435 | 381 | GenCompactClosure blk; |
duke@435 | 382 | gch->generation_iterate(&blk, true); |
duke@435 | 383 | |
duke@435 | 384 | VALIDATE_MARK_SWEEP_ONLY(compaction_complete()); |
duke@435 | 385 | |
duke@435 | 386 | pg->post_compact(); // Shared spaces verification. |
duke@435 | 387 | } |