Wed, 09 Jul 2008 15:08:55 -0700
6672698: mangle_unused_area() should not remangle the entire heap at each collection.
Summary: Maintain a high water mark for the allocations in a space and mangle only up to that high water mark.
Reviewed-by: ysr, apetrusenko
duke@435 | 1 | /* |
duke@435 | 2 | * Copyright 2001-2007 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/_parNewGeneration.cpp.incl" |
duke@435 | 27 | |
duke@435 | 28 | #ifdef _MSC_VER |
duke@435 | 29 | #pragma warning( push ) |
duke@435 | 30 | #pragma warning( disable:4355 ) // 'this' : used in base member initializer list |
duke@435 | 31 | #endif |
duke@435 | 32 | ParScanThreadState::ParScanThreadState(Space* to_space_, |
duke@435 | 33 | ParNewGeneration* gen_, |
duke@435 | 34 | Generation* old_gen_, |
duke@435 | 35 | int thread_num_, |
duke@435 | 36 | ObjToScanQueueSet* work_queue_set_, |
duke@435 | 37 | size_t desired_plab_sz_, |
duke@435 | 38 | ParallelTaskTerminator& term_) : |
duke@435 | 39 | _to_space(to_space_), _old_gen(old_gen_), _thread_num(thread_num_), |
duke@435 | 40 | _work_queue(work_queue_set_->queue(thread_num_)), _to_space_full(false), |
duke@435 | 41 | _ageTable(false), // false ==> not the global age table, no perf data. |
duke@435 | 42 | _to_space_alloc_buffer(desired_plab_sz_), |
duke@435 | 43 | _to_space_closure(gen_, this), _old_gen_closure(gen_, this), |
duke@435 | 44 | _to_space_root_closure(gen_, this), _old_gen_root_closure(gen_, this), |
duke@435 | 45 | _older_gen_closure(gen_, this), |
duke@435 | 46 | _evacuate_followers(this, &_to_space_closure, &_old_gen_closure, |
duke@435 | 47 | &_to_space_root_closure, gen_, &_old_gen_root_closure, |
duke@435 | 48 | work_queue_set_, &term_), |
duke@435 | 49 | _is_alive_closure(gen_), _scan_weak_ref_closure(gen_, this), |
duke@435 | 50 | _keep_alive_closure(&_scan_weak_ref_closure), |
duke@435 | 51 | _pushes(0), _pops(0), _steals(0), _steal_attempts(0), _term_attempts(0), |
duke@435 | 52 | _strong_roots_time(0.0), _term_time(0.0) |
duke@435 | 53 | { |
duke@435 | 54 | _survivor_chunk_array = |
duke@435 | 55 | (ChunkArray*) old_gen()->get_data_recorder(thread_num()); |
duke@435 | 56 | _hash_seed = 17; // Might want to take time-based random value. |
duke@435 | 57 | _start = os::elapsedTime(); |
duke@435 | 58 | _old_gen_closure.set_generation(old_gen_); |
duke@435 | 59 | _old_gen_root_closure.set_generation(old_gen_); |
duke@435 | 60 | } |
duke@435 | 61 | #ifdef _MSC_VER |
duke@435 | 62 | #pragma warning( pop ) |
duke@435 | 63 | #endif |
duke@435 | 64 | |
duke@435 | 65 | void ParScanThreadState::record_survivor_plab(HeapWord* plab_start, |
duke@435 | 66 | size_t plab_word_size) { |
duke@435 | 67 | ChunkArray* sca = survivor_chunk_array(); |
duke@435 | 68 | if (sca != NULL) { |
duke@435 | 69 | // A non-null SCA implies that we want the PLAB data recorded. |
duke@435 | 70 | sca->record_sample(plab_start, plab_word_size); |
duke@435 | 71 | } |
duke@435 | 72 | } |
duke@435 | 73 | |
duke@435 | 74 | bool ParScanThreadState::should_be_partially_scanned(oop new_obj, oop old_obj) const { |
duke@435 | 75 | return new_obj->is_objArray() && |
duke@435 | 76 | arrayOop(new_obj)->length() > ParGCArrayScanChunk && |
duke@435 | 77 | new_obj != old_obj; |
duke@435 | 78 | } |
duke@435 | 79 | |
duke@435 | 80 | void ParScanThreadState::scan_partial_array_and_push_remainder(oop old) { |
duke@435 | 81 | assert(old->is_objArray(), "must be obj array"); |
duke@435 | 82 | assert(old->is_forwarded(), "must be forwarded"); |
duke@435 | 83 | assert(Universe::heap()->is_in_reserved(old), "must be in heap."); |
duke@435 | 84 | assert(!_old_gen->is_in(old), "must be in young generation."); |
duke@435 | 85 | |
duke@435 | 86 | objArrayOop obj = objArrayOop(old->forwardee()); |
duke@435 | 87 | // Process ParGCArrayScanChunk elements now |
duke@435 | 88 | // and push the remainder back onto queue |
duke@435 | 89 | int start = arrayOop(old)->length(); |
duke@435 | 90 | int end = obj->length(); |
duke@435 | 91 | int remainder = end - start; |
duke@435 | 92 | assert(start <= end, "just checking"); |
duke@435 | 93 | if (remainder > 2 * ParGCArrayScanChunk) { |
duke@435 | 94 | // Test above combines last partial chunk with a full chunk |
duke@435 | 95 | end = start + ParGCArrayScanChunk; |
duke@435 | 96 | arrayOop(old)->set_length(end); |
duke@435 | 97 | // Push remainder. |
duke@435 | 98 | bool ok = work_queue()->push(old); |
duke@435 | 99 | assert(ok, "just popped, push must be okay"); |
duke@435 | 100 | note_push(); |
duke@435 | 101 | } else { |
duke@435 | 102 | // Restore length so that it can be used if there |
duke@435 | 103 | // is a promotion failure and forwarding pointers |
duke@435 | 104 | // must be removed. |
duke@435 | 105 | arrayOop(old)->set_length(end); |
duke@435 | 106 | } |
coleenp@548 | 107 | |
duke@435 | 108 | // process our set of indices (include header in first chunk) |
coleenp@548 | 109 | // should make sure end is even (aligned to HeapWord in case of compressed oops) |
duke@435 | 110 | if ((HeapWord *)obj < young_old_boundary()) { |
duke@435 | 111 | // object is in to_space |
coleenp@548 | 112 | obj->oop_iterate_range(&_to_space_closure, start, end); |
duke@435 | 113 | } else { |
duke@435 | 114 | // object is in old generation |
coleenp@548 | 115 | obj->oop_iterate_range(&_old_gen_closure, start, end); |
duke@435 | 116 | } |
duke@435 | 117 | } |
duke@435 | 118 | |
duke@435 | 119 | |
duke@435 | 120 | void ParScanThreadState::trim_queues(int max_size) { |
duke@435 | 121 | ObjToScanQueue* queue = work_queue(); |
duke@435 | 122 | while (queue->size() > (juint)max_size) { |
duke@435 | 123 | oop obj_to_scan; |
duke@435 | 124 | if (queue->pop_local(obj_to_scan)) { |
duke@435 | 125 | note_pop(); |
duke@435 | 126 | |
duke@435 | 127 | if ((HeapWord *)obj_to_scan < young_old_boundary()) { |
duke@435 | 128 | if (obj_to_scan->is_objArray() && |
duke@435 | 129 | obj_to_scan->is_forwarded() && |
duke@435 | 130 | obj_to_scan->forwardee() != obj_to_scan) { |
duke@435 | 131 | scan_partial_array_and_push_remainder(obj_to_scan); |
duke@435 | 132 | } else { |
duke@435 | 133 | // object is in to_space |
duke@435 | 134 | obj_to_scan->oop_iterate(&_to_space_closure); |
duke@435 | 135 | } |
duke@435 | 136 | } else { |
duke@435 | 137 | // object is in old generation |
duke@435 | 138 | obj_to_scan->oop_iterate(&_old_gen_closure); |
duke@435 | 139 | } |
duke@435 | 140 | } |
duke@435 | 141 | } |
duke@435 | 142 | } |
duke@435 | 143 | |
duke@435 | 144 | HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) { |
duke@435 | 145 | |
duke@435 | 146 | // Otherwise, if the object is small enough, try to reallocate the |
duke@435 | 147 | // buffer. |
duke@435 | 148 | HeapWord* obj = NULL; |
duke@435 | 149 | if (!_to_space_full) { |
duke@435 | 150 | ParGCAllocBuffer* const plab = to_space_alloc_buffer(); |
duke@435 | 151 | Space* const sp = to_space(); |
duke@435 | 152 | if (word_sz * 100 < |
duke@435 | 153 | ParallelGCBufferWastePct * plab->word_sz()) { |
duke@435 | 154 | // Is small enough; abandon this buffer and start a new one. |
duke@435 | 155 | plab->retire(false, false); |
duke@435 | 156 | size_t buf_size = plab->word_sz(); |
duke@435 | 157 | HeapWord* buf_space = sp->par_allocate(buf_size); |
duke@435 | 158 | if (buf_space == NULL) { |
duke@435 | 159 | const size_t min_bytes = |
duke@435 | 160 | ParGCAllocBuffer::min_size() << LogHeapWordSize; |
duke@435 | 161 | size_t free_bytes = sp->free(); |
duke@435 | 162 | while(buf_space == NULL && free_bytes >= min_bytes) { |
duke@435 | 163 | buf_size = free_bytes >> LogHeapWordSize; |
duke@435 | 164 | assert(buf_size == (size_t)align_object_size(buf_size), |
duke@435 | 165 | "Invariant"); |
duke@435 | 166 | buf_space = sp->par_allocate(buf_size); |
duke@435 | 167 | free_bytes = sp->free(); |
duke@435 | 168 | } |
duke@435 | 169 | } |
duke@435 | 170 | if (buf_space != NULL) { |
duke@435 | 171 | plab->set_word_size(buf_size); |
duke@435 | 172 | plab->set_buf(buf_space); |
duke@435 | 173 | record_survivor_plab(buf_space, buf_size); |
duke@435 | 174 | obj = plab->allocate(word_sz); |
duke@435 | 175 | // Note that we cannot compare buf_size < word_sz below |
duke@435 | 176 | // because of AlignmentReserve (see ParGCAllocBuffer::allocate()). |
duke@435 | 177 | assert(obj != NULL || plab->words_remaining() < word_sz, |
duke@435 | 178 | "Else should have been able to allocate"); |
duke@435 | 179 | // It's conceivable that we may be able to use the |
duke@435 | 180 | // buffer we just grabbed for subsequent small requests |
duke@435 | 181 | // even if not for this one. |
duke@435 | 182 | } else { |
duke@435 | 183 | // We're used up. |
duke@435 | 184 | _to_space_full = true; |
duke@435 | 185 | } |
duke@435 | 186 | |
duke@435 | 187 | } else { |
duke@435 | 188 | // Too large; allocate the object individually. |
duke@435 | 189 | obj = sp->par_allocate(word_sz); |
duke@435 | 190 | } |
duke@435 | 191 | } |
duke@435 | 192 | return obj; |
duke@435 | 193 | } |
duke@435 | 194 | |
duke@435 | 195 | |
duke@435 | 196 | void ParScanThreadState::undo_alloc_in_to_space(HeapWord* obj, |
duke@435 | 197 | size_t word_sz) { |
duke@435 | 198 | // Is the alloc in the current alloc buffer? |
duke@435 | 199 | if (to_space_alloc_buffer()->contains(obj)) { |
duke@435 | 200 | assert(to_space_alloc_buffer()->contains(obj + word_sz - 1), |
duke@435 | 201 | "Should contain whole object."); |
duke@435 | 202 | to_space_alloc_buffer()->undo_allocation(obj, word_sz); |
duke@435 | 203 | } else { |
duke@435 | 204 | SharedHeap::fill_region_with_object(MemRegion(obj, word_sz)); |
duke@435 | 205 | } |
duke@435 | 206 | } |
duke@435 | 207 | |
duke@435 | 208 | class ParScanThreadStateSet: private ResourceArray { |
duke@435 | 209 | public: |
duke@435 | 210 | // Initializes states for the specified number of threads; |
duke@435 | 211 | ParScanThreadStateSet(int num_threads, |
duke@435 | 212 | Space& to_space, |
duke@435 | 213 | ParNewGeneration& gen, |
duke@435 | 214 | Generation& old_gen, |
duke@435 | 215 | ObjToScanQueueSet& queue_set, |
duke@435 | 216 | size_t desired_plab_sz, |
duke@435 | 217 | ParallelTaskTerminator& term); |
duke@435 | 218 | inline ParScanThreadState& thread_sate(int i); |
duke@435 | 219 | int pushes() { return _pushes; } |
duke@435 | 220 | int pops() { return _pops; } |
duke@435 | 221 | int steals() { return _steals; } |
duke@435 | 222 | void reset(); |
duke@435 | 223 | void flush(); |
duke@435 | 224 | private: |
duke@435 | 225 | ParallelTaskTerminator& _term; |
duke@435 | 226 | ParNewGeneration& _gen; |
duke@435 | 227 | Generation& _next_gen; |
duke@435 | 228 | // staticstics |
duke@435 | 229 | int _pushes; |
duke@435 | 230 | int _pops; |
duke@435 | 231 | int _steals; |
duke@435 | 232 | }; |
duke@435 | 233 | |
duke@435 | 234 | |
duke@435 | 235 | ParScanThreadStateSet::ParScanThreadStateSet( |
duke@435 | 236 | int num_threads, Space& to_space, ParNewGeneration& gen, |
duke@435 | 237 | Generation& old_gen, ObjToScanQueueSet& queue_set, |
duke@435 | 238 | size_t desired_plab_sz, ParallelTaskTerminator& term) |
duke@435 | 239 | : ResourceArray(sizeof(ParScanThreadState), num_threads), |
duke@435 | 240 | _gen(gen), _next_gen(old_gen), _term(term), |
duke@435 | 241 | _pushes(0), _pops(0), _steals(0) |
duke@435 | 242 | { |
duke@435 | 243 | assert(num_threads > 0, "sanity check!"); |
duke@435 | 244 | // Initialize states. |
duke@435 | 245 | for (int i = 0; i < num_threads; ++i) { |
duke@435 | 246 | new ((ParScanThreadState*)_data + i) |
duke@435 | 247 | ParScanThreadState(&to_space, &gen, &old_gen, i, &queue_set, |
duke@435 | 248 | desired_plab_sz, term); |
duke@435 | 249 | } |
duke@435 | 250 | } |
duke@435 | 251 | |
duke@435 | 252 | inline ParScanThreadState& ParScanThreadStateSet::thread_sate(int i) |
duke@435 | 253 | { |
duke@435 | 254 | assert(i >= 0 && i < length(), "sanity check!"); |
duke@435 | 255 | return ((ParScanThreadState*)_data)[i]; |
duke@435 | 256 | } |
duke@435 | 257 | |
duke@435 | 258 | |
duke@435 | 259 | void ParScanThreadStateSet::reset() |
duke@435 | 260 | { |
duke@435 | 261 | _term.reset_for_reuse(); |
duke@435 | 262 | } |
duke@435 | 263 | |
duke@435 | 264 | void ParScanThreadStateSet::flush() |
duke@435 | 265 | { |
duke@435 | 266 | for (int i = 0; i < length(); ++i) { |
duke@435 | 267 | ParScanThreadState& par_scan_state = thread_sate(i); |
duke@435 | 268 | |
duke@435 | 269 | // Flush stats related to To-space PLAB activity and |
duke@435 | 270 | // retire the last buffer. |
duke@435 | 271 | par_scan_state.to_space_alloc_buffer()-> |
duke@435 | 272 | flush_stats_and_retire(_gen.plab_stats(), |
duke@435 | 273 | false /* !retain */); |
duke@435 | 274 | |
duke@435 | 275 | // Every thread has its own age table. We need to merge |
duke@435 | 276 | // them all into one. |
duke@435 | 277 | ageTable *local_table = par_scan_state.age_table(); |
duke@435 | 278 | _gen.age_table()->merge(local_table); |
duke@435 | 279 | |
duke@435 | 280 | // Inform old gen that we're done. |
duke@435 | 281 | _next_gen.par_promote_alloc_done(i); |
duke@435 | 282 | _next_gen.par_oop_since_save_marks_iterate_done(i); |
duke@435 | 283 | |
duke@435 | 284 | // Flush stats related to work queue activity (push/pop/steal) |
duke@435 | 285 | // This could conceivably become a bottleneck; if so, we'll put the |
duke@435 | 286 | // stat's gathering under the flag. |
duke@435 | 287 | if (PAR_STATS_ENABLED) { |
duke@435 | 288 | _pushes += par_scan_state.pushes(); |
duke@435 | 289 | _pops += par_scan_state.pops(); |
duke@435 | 290 | _steals += par_scan_state.steals(); |
duke@435 | 291 | if (ParallelGCVerbose) { |
duke@435 | 292 | gclog_or_tty->print("Thread %d complete:\n" |
duke@435 | 293 | " Pushes: %7d Pops: %7d Steals %7d (in %d attempts)\n", |
duke@435 | 294 | i, par_scan_state.pushes(), par_scan_state.pops(), |
duke@435 | 295 | par_scan_state.steals(), par_scan_state.steal_attempts()); |
duke@435 | 296 | if (par_scan_state.overflow_pushes() > 0 || |
duke@435 | 297 | par_scan_state.overflow_refills() > 0) { |
duke@435 | 298 | gclog_or_tty->print(" Overflow pushes: %7d " |
duke@435 | 299 | "Overflow refills: %7d for %d objs.\n", |
duke@435 | 300 | par_scan_state.overflow_pushes(), |
duke@435 | 301 | par_scan_state.overflow_refills(), |
duke@435 | 302 | par_scan_state.overflow_refill_objs()); |
duke@435 | 303 | } |
duke@435 | 304 | |
duke@435 | 305 | double elapsed = par_scan_state.elapsed(); |
duke@435 | 306 | double strong_roots = par_scan_state.strong_roots_time(); |
duke@435 | 307 | double term = par_scan_state.term_time(); |
duke@435 | 308 | gclog_or_tty->print( |
duke@435 | 309 | " Elapsed: %7.2f ms.\n" |
duke@435 | 310 | " Strong roots: %7.2f ms (%6.2f%%)\n" |
duke@435 | 311 | " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n", |
duke@435 | 312 | elapsed * 1000.0, |
duke@435 | 313 | strong_roots * 1000.0, (strong_roots*100.0/elapsed), |
duke@435 | 314 | term * 1000.0, (term*100.0/elapsed), |
duke@435 | 315 | par_scan_state.term_attempts()); |
duke@435 | 316 | } |
duke@435 | 317 | } |
duke@435 | 318 | } |
duke@435 | 319 | } |
duke@435 | 320 | |
duke@435 | 321 | ParScanClosure::ParScanClosure(ParNewGeneration* g, |
duke@435 | 322 | ParScanThreadState* par_scan_state) : |
duke@435 | 323 | OopsInGenClosure(g), _par_scan_state(par_scan_state), _g(g) |
duke@435 | 324 | { |
duke@435 | 325 | assert(_g->level() == 0, "Optimized for youngest generation"); |
duke@435 | 326 | _boundary = _g->reserved().end(); |
duke@435 | 327 | } |
duke@435 | 328 | |
coleenp@548 | 329 | void ParScanWithBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, false); } |
coleenp@548 | 330 | void ParScanWithBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, false); } |
coleenp@548 | 331 | |
coleenp@548 | 332 | void ParScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, false); } |
coleenp@548 | 333 | void ParScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, false); } |
coleenp@548 | 334 | |
coleenp@548 | 335 | void ParRootScanWithBarrierTwoGensClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, true); } |
coleenp@548 | 336 | void ParRootScanWithBarrierTwoGensClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, true); } |
coleenp@548 | 337 | |
coleenp@548 | 338 | void ParRootScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, true); } |
coleenp@548 | 339 | void ParRootScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, true); } |
coleenp@548 | 340 | |
duke@435 | 341 | ParScanWeakRefClosure::ParScanWeakRefClosure(ParNewGeneration* g, |
duke@435 | 342 | ParScanThreadState* par_scan_state) |
duke@435 | 343 | : ScanWeakRefClosure(g), _par_scan_state(par_scan_state) |
coleenp@548 | 344 | {} |
coleenp@548 | 345 | |
coleenp@548 | 346 | void ParScanWeakRefClosure::do_oop(oop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
coleenp@548 | 347 | void ParScanWeakRefClosure::do_oop(narrowOop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
duke@435 | 348 | |
duke@435 | 349 | #ifdef WIN32 |
duke@435 | 350 | #pragma warning(disable: 4786) /* identifier was truncated to '255' characters in the browser information */ |
duke@435 | 351 | #endif |
duke@435 | 352 | |
duke@435 | 353 | ParEvacuateFollowersClosure::ParEvacuateFollowersClosure( |
duke@435 | 354 | ParScanThreadState* par_scan_state_, |
duke@435 | 355 | ParScanWithoutBarrierClosure* to_space_closure_, |
duke@435 | 356 | ParScanWithBarrierClosure* old_gen_closure_, |
duke@435 | 357 | ParRootScanWithoutBarrierClosure* to_space_root_closure_, |
duke@435 | 358 | ParNewGeneration* par_gen_, |
duke@435 | 359 | ParRootScanWithBarrierTwoGensClosure* old_gen_root_closure_, |
duke@435 | 360 | ObjToScanQueueSet* task_queues_, |
duke@435 | 361 | ParallelTaskTerminator* terminator_) : |
duke@435 | 362 | |
duke@435 | 363 | _par_scan_state(par_scan_state_), |
duke@435 | 364 | _to_space_closure(to_space_closure_), |
duke@435 | 365 | _old_gen_closure(old_gen_closure_), |
duke@435 | 366 | _to_space_root_closure(to_space_root_closure_), |
duke@435 | 367 | _old_gen_root_closure(old_gen_root_closure_), |
duke@435 | 368 | _par_gen(par_gen_), |
duke@435 | 369 | _task_queues(task_queues_), |
duke@435 | 370 | _terminator(terminator_) |
duke@435 | 371 | {} |
duke@435 | 372 | |
duke@435 | 373 | void ParEvacuateFollowersClosure::do_void() { |
duke@435 | 374 | ObjToScanQueue* work_q = par_scan_state()->work_queue(); |
duke@435 | 375 | |
duke@435 | 376 | while (true) { |
duke@435 | 377 | |
duke@435 | 378 | // Scan to-space and old-gen objs until we run out of both. |
duke@435 | 379 | oop obj_to_scan; |
duke@435 | 380 | par_scan_state()->trim_queues(0); |
duke@435 | 381 | |
duke@435 | 382 | // We have no local work, attempt to steal from other threads. |
duke@435 | 383 | |
duke@435 | 384 | // attempt to steal work from promoted. |
duke@435 | 385 | par_scan_state()->note_steal_attempt(); |
duke@435 | 386 | if (task_queues()->steal(par_scan_state()->thread_num(), |
duke@435 | 387 | par_scan_state()->hash_seed(), |
duke@435 | 388 | obj_to_scan)) { |
duke@435 | 389 | par_scan_state()->note_steal(); |
duke@435 | 390 | bool res = work_q->push(obj_to_scan); |
duke@435 | 391 | assert(res, "Empty queue should have room for a push."); |
duke@435 | 392 | |
duke@435 | 393 | par_scan_state()->note_push(); |
duke@435 | 394 | // if successful, goto Start. |
duke@435 | 395 | continue; |
duke@435 | 396 | |
duke@435 | 397 | // try global overflow list. |
duke@435 | 398 | } else if (par_gen()->take_from_overflow_list(par_scan_state())) { |
duke@435 | 399 | continue; |
duke@435 | 400 | } |
duke@435 | 401 | |
duke@435 | 402 | // Otherwise, offer termination. |
duke@435 | 403 | par_scan_state()->start_term_time(); |
duke@435 | 404 | if (terminator()->offer_termination()) break; |
duke@435 | 405 | par_scan_state()->end_term_time(); |
duke@435 | 406 | } |
duke@435 | 407 | // Finish the last termination pause. |
duke@435 | 408 | par_scan_state()->end_term_time(); |
duke@435 | 409 | } |
duke@435 | 410 | |
duke@435 | 411 | ParNewGenTask::ParNewGenTask(ParNewGeneration* gen, Generation* next_gen, |
duke@435 | 412 | HeapWord* young_old_boundary, ParScanThreadStateSet* state_set) : |
duke@435 | 413 | AbstractGangTask("ParNewGeneration collection"), |
duke@435 | 414 | _gen(gen), _next_gen(next_gen), |
duke@435 | 415 | _young_old_boundary(young_old_boundary), |
duke@435 | 416 | _state_set(state_set) |
duke@435 | 417 | {} |
duke@435 | 418 | |
duke@435 | 419 | void ParNewGenTask::work(int i) { |
duke@435 | 420 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 421 | // Since this is being done in a separate thread, need new resource |
duke@435 | 422 | // and handle marks. |
duke@435 | 423 | ResourceMark rm; |
duke@435 | 424 | HandleMark hm; |
duke@435 | 425 | // We would need multiple old-gen queues otherwise. |
duke@435 | 426 | guarantee(gch->n_gens() == 2, |
duke@435 | 427 | "Par young collection currently only works with one older gen."); |
duke@435 | 428 | |
duke@435 | 429 | Generation* old_gen = gch->next_gen(_gen); |
duke@435 | 430 | |
duke@435 | 431 | ParScanThreadState& par_scan_state = _state_set->thread_sate(i); |
duke@435 | 432 | par_scan_state.set_young_old_boundary(_young_old_boundary); |
duke@435 | 433 | |
duke@435 | 434 | par_scan_state.start_strong_roots(); |
duke@435 | 435 | gch->gen_process_strong_roots(_gen->level(), |
duke@435 | 436 | true, // Process younger gens, if any, |
duke@435 | 437 | // as strong roots. |
duke@435 | 438 | false,// not collecting perm generation. |
duke@435 | 439 | SharedHeap::SO_AllClasses, |
duke@435 | 440 | &par_scan_state.older_gen_closure(), |
duke@435 | 441 | &par_scan_state.to_space_root_closure()); |
duke@435 | 442 | par_scan_state.end_strong_roots(); |
duke@435 | 443 | |
duke@435 | 444 | // "evacuate followers". |
duke@435 | 445 | par_scan_state.evacuate_followers_closure().do_void(); |
duke@435 | 446 | } |
duke@435 | 447 | |
duke@435 | 448 | #ifdef _MSC_VER |
duke@435 | 449 | #pragma warning( push ) |
duke@435 | 450 | #pragma warning( disable:4355 ) // 'this' : used in base member initializer list |
duke@435 | 451 | #endif |
duke@435 | 452 | ParNewGeneration:: |
duke@435 | 453 | ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level) |
duke@435 | 454 | : DefNewGeneration(rs, initial_byte_size, level, "PCopy"), |
duke@435 | 455 | _overflow_list(NULL), |
duke@435 | 456 | _is_alive_closure(this), |
duke@435 | 457 | _plab_stats(YoungPLABSize, PLABWeight) |
duke@435 | 458 | { |
duke@435 | 459 | _task_queues = new ObjToScanQueueSet(ParallelGCThreads); |
duke@435 | 460 | guarantee(_task_queues != NULL, "task_queues allocation failure."); |
duke@435 | 461 | |
duke@435 | 462 | for (uint i1 = 0; i1 < ParallelGCThreads; i1++) { |
duke@435 | 463 | ObjToScanQueuePadded *q_padded = new ObjToScanQueuePadded(); |
duke@435 | 464 | guarantee(q_padded != NULL, "work_queue Allocation failure."); |
duke@435 | 465 | |
duke@435 | 466 | _task_queues->register_queue(i1, &q_padded->work_queue); |
duke@435 | 467 | } |
duke@435 | 468 | |
duke@435 | 469 | for (uint i2 = 0; i2 < ParallelGCThreads; i2++) |
duke@435 | 470 | _task_queues->queue(i2)->initialize(); |
duke@435 | 471 | |
duke@435 | 472 | if (UsePerfData) { |
duke@435 | 473 | EXCEPTION_MARK; |
duke@435 | 474 | ResourceMark rm; |
duke@435 | 475 | |
duke@435 | 476 | const char* cname = |
duke@435 | 477 | PerfDataManager::counter_name(_gen_counters->name_space(), "threads"); |
duke@435 | 478 | PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None, |
duke@435 | 479 | ParallelGCThreads, CHECK); |
duke@435 | 480 | } |
duke@435 | 481 | } |
duke@435 | 482 | #ifdef _MSC_VER |
duke@435 | 483 | #pragma warning( pop ) |
duke@435 | 484 | #endif |
duke@435 | 485 | |
duke@435 | 486 | // ParNewGeneration:: |
duke@435 | 487 | ParKeepAliveClosure::ParKeepAliveClosure(ParScanWeakRefClosure* cl) : |
duke@435 | 488 | DefNewGeneration::KeepAliveClosure(cl), _par_cl(cl) {} |
duke@435 | 489 | |
coleenp@548 | 490 | template <class T> |
coleenp@548 | 491 | void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop_work(T* p) { |
coleenp@548 | 492 | #ifdef ASSERT |
coleenp@548 | 493 | { |
coleenp@548 | 494 | assert(!oopDesc::is_null(*p), "expected non-null ref"); |
coleenp@548 | 495 | oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
coleenp@548 | 496 | // We never expect to see a null reference being processed |
coleenp@548 | 497 | // as a weak reference. |
coleenp@548 | 498 | assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
coleenp@548 | 499 | } |
coleenp@548 | 500 | #endif // ASSERT |
duke@435 | 501 | |
duke@435 | 502 | _par_cl->do_oop_nv(p); |
duke@435 | 503 | |
duke@435 | 504 | if (Universe::heap()->is_in_reserved(p)) { |
coleenp@548 | 505 | oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
coleenp@548 | 506 | _rs->write_ref_field_gc_par(p, obj); |
duke@435 | 507 | } |
duke@435 | 508 | } |
duke@435 | 509 | |
coleenp@548 | 510 | void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(oop* p) { ParKeepAliveClosure::do_oop_work(p); } |
coleenp@548 | 511 | void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(narrowOop* p) { ParKeepAliveClosure::do_oop_work(p); } |
coleenp@548 | 512 | |
duke@435 | 513 | // ParNewGeneration:: |
duke@435 | 514 | KeepAliveClosure::KeepAliveClosure(ScanWeakRefClosure* cl) : |
duke@435 | 515 | DefNewGeneration::KeepAliveClosure(cl) {} |
duke@435 | 516 | |
coleenp@548 | 517 | template <class T> |
coleenp@548 | 518 | void /*ParNewGeneration::*/KeepAliveClosure::do_oop_work(T* p) { |
coleenp@548 | 519 | #ifdef ASSERT |
coleenp@548 | 520 | { |
coleenp@548 | 521 | assert(!oopDesc::is_null(*p), "expected non-null ref"); |
coleenp@548 | 522 | oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
coleenp@548 | 523 | // We never expect to see a null reference being processed |
coleenp@548 | 524 | // as a weak reference. |
coleenp@548 | 525 | assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
coleenp@548 | 526 | } |
coleenp@548 | 527 | #endif // ASSERT |
duke@435 | 528 | |
duke@435 | 529 | _cl->do_oop_nv(p); |
duke@435 | 530 | |
duke@435 | 531 | if (Universe::heap()->is_in_reserved(p)) { |
coleenp@548 | 532 | oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
coleenp@548 | 533 | _rs->write_ref_field_gc_par(p, obj); |
duke@435 | 534 | } |
duke@435 | 535 | } |
duke@435 | 536 | |
coleenp@548 | 537 | void /*ParNewGeneration::*/KeepAliveClosure::do_oop(oop* p) { KeepAliveClosure::do_oop_work(p); } |
coleenp@548 | 538 | void /*ParNewGeneration::*/KeepAliveClosure::do_oop(narrowOop* p) { KeepAliveClosure::do_oop_work(p); } |
coleenp@548 | 539 | |
coleenp@548 | 540 | template <class T> void ScanClosureWithParBarrier::do_oop_work(T* p) { |
coleenp@548 | 541 | T heap_oop = oopDesc::load_heap_oop(p); |
coleenp@548 | 542 | if (!oopDesc::is_null(heap_oop)) { |
coleenp@548 | 543 | oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
duke@435 | 544 | if ((HeapWord*)obj < _boundary) { |
duke@435 | 545 | assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?"); |
coleenp@548 | 546 | oop new_obj = obj->is_forwarded() |
coleenp@548 | 547 | ? obj->forwardee() |
coleenp@548 | 548 | : _g->DefNewGeneration::copy_to_survivor_space(obj); |
coleenp@548 | 549 | oopDesc::encode_store_heap_oop_not_null(p, new_obj); |
duke@435 | 550 | } |
duke@435 | 551 | if (_gc_barrier) { |
duke@435 | 552 | // If p points to a younger generation, mark the card. |
duke@435 | 553 | if ((HeapWord*)obj < _gen_boundary) { |
duke@435 | 554 | _rs->write_ref_field_gc_par(p, obj); |
duke@435 | 555 | } |
duke@435 | 556 | } |
duke@435 | 557 | } |
duke@435 | 558 | } |
duke@435 | 559 | |
coleenp@548 | 560 | void ScanClosureWithParBarrier::do_oop(oop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
coleenp@548 | 561 | void ScanClosureWithParBarrier::do_oop(narrowOop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
coleenp@548 | 562 | |
duke@435 | 563 | class ParNewRefProcTaskProxy: public AbstractGangTask { |
duke@435 | 564 | typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; |
duke@435 | 565 | public: |
duke@435 | 566 | ParNewRefProcTaskProxy(ProcessTask& task, ParNewGeneration& gen, |
duke@435 | 567 | Generation& next_gen, |
duke@435 | 568 | HeapWord* young_old_boundary, |
duke@435 | 569 | ParScanThreadStateSet& state_set); |
duke@435 | 570 | |
duke@435 | 571 | private: |
duke@435 | 572 | virtual void work(int i); |
duke@435 | 573 | |
duke@435 | 574 | private: |
duke@435 | 575 | ParNewGeneration& _gen; |
duke@435 | 576 | ProcessTask& _task; |
duke@435 | 577 | Generation& _next_gen; |
duke@435 | 578 | HeapWord* _young_old_boundary; |
duke@435 | 579 | ParScanThreadStateSet& _state_set; |
duke@435 | 580 | }; |
duke@435 | 581 | |
duke@435 | 582 | ParNewRefProcTaskProxy::ParNewRefProcTaskProxy( |
duke@435 | 583 | ProcessTask& task, ParNewGeneration& gen, |
duke@435 | 584 | Generation& next_gen, |
duke@435 | 585 | HeapWord* young_old_boundary, |
duke@435 | 586 | ParScanThreadStateSet& state_set) |
duke@435 | 587 | : AbstractGangTask("ParNewGeneration parallel reference processing"), |
duke@435 | 588 | _gen(gen), |
duke@435 | 589 | _task(task), |
duke@435 | 590 | _next_gen(next_gen), |
duke@435 | 591 | _young_old_boundary(young_old_boundary), |
duke@435 | 592 | _state_set(state_set) |
duke@435 | 593 | { |
duke@435 | 594 | } |
duke@435 | 595 | |
duke@435 | 596 | void ParNewRefProcTaskProxy::work(int i) |
duke@435 | 597 | { |
duke@435 | 598 | ResourceMark rm; |
duke@435 | 599 | HandleMark hm; |
duke@435 | 600 | ParScanThreadState& par_scan_state = _state_set.thread_sate(i); |
duke@435 | 601 | par_scan_state.set_young_old_boundary(_young_old_boundary); |
duke@435 | 602 | _task.work(i, par_scan_state.is_alive_closure(), |
duke@435 | 603 | par_scan_state.keep_alive_closure(), |
duke@435 | 604 | par_scan_state.evacuate_followers_closure()); |
duke@435 | 605 | } |
duke@435 | 606 | |
duke@435 | 607 | class ParNewRefEnqueueTaskProxy: public AbstractGangTask { |
duke@435 | 608 | typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; |
duke@435 | 609 | EnqueueTask& _task; |
duke@435 | 610 | |
duke@435 | 611 | public: |
duke@435 | 612 | ParNewRefEnqueueTaskProxy(EnqueueTask& task) |
duke@435 | 613 | : AbstractGangTask("ParNewGeneration parallel reference enqueue"), |
duke@435 | 614 | _task(task) |
duke@435 | 615 | { } |
duke@435 | 616 | |
duke@435 | 617 | virtual void work(int i) |
duke@435 | 618 | { |
duke@435 | 619 | _task.work(i); |
duke@435 | 620 | } |
duke@435 | 621 | }; |
duke@435 | 622 | |
duke@435 | 623 | |
duke@435 | 624 | void ParNewRefProcTaskExecutor::execute(ProcessTask& task) |
duke@435 | 625 | { |
duke@435 | 626 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 627 | assert(gch->kind() == CollectedHeap::GenCollectedHeap, |
duke@435 | 628 | "not a generational heap"); |
duke@435 | 629 | WorkGang* workers = gch->workers(); |
duke@435 | 630 | assert(workers != NULL, "Need parallel worker threads."); |
duke@435 | 631 | ParNewRefProcTaskProxy rp_task(task, _generation, *_generation.next_gen(), |
duke@435 | 632 | _generation.reserved().end(), _state_set); |
duke@435 | 633 | workers->run_task(&rp_task); |
duke@435 | 634 | _state_set.reset(); |
duke@435 | 635 | } |
duke@435 | 636 | |
duke@435 | 637 | void ParNewRefProcTaskExecutor::execute(EnqueueTask& task) |
duke@435 | 638 | { |
duke@435 | 639 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 640 | WorkGang* workers = gch->workers(); |
duke@435 | 641 | assert(workers != NULL, "Need parallel worker threads."); |
duke@435 | 642 | ParNewRefEnqueueTaskProxy enq_task(task); |
duke@435 | 643 | workers->run_task(&enq_task); |
duke@435 | 644 | } |
duke@435 | 645 | |
duke@435 | 646 | void ParNewRefProcTaskExecutor::set_single_threaded_mode() |
duke@435 | 647 | { |
duke@435 | 648 | _state_set.flush(); |
duke@435 | 649 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 650 | gch->set_par_threads(0); // 0 ==> non-parallel. |
duke@435 | 651 | gch->save_marks(); |
duke@435 | 652 | } |
duke@435 | 653 | |
duke@435 | 654 | ScanClosureWithParBarrier:: |
duke@435 | 655 | ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier) : |
duke@435 | 656 | ScanClosure(g, gc_barrier) {} |
duke@435 | 657 | |
duke@435 | 658 | EvacuateFollowersClosureGeneral:: |
duke@435 | 659 | EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, |
duke@435 | 660 | OopsInGenClosure* cur, |
duke@435 | 661 | OopsInGenClosure* older) : |
duke@435 | 662 | _gch(gch), _level(level), |
duke@435 | 663 | _scan_cur_or_nonheap(cur), _scan_older(older) |
duke@435 | 664 | {} |
duke@435 | 665 | |
duke@435 | 666 | void EvacuateFollowersClosureGeneral::do_void() { |
duke@435 | 667 | do { |
duke@435 | 668 | // Beware: this call will lead to closure applications via virtual |
duke@435 | 669 | // calls. |
duke@435 | 670 | _gch->oop_since_save_marks_iterate(_level, |
duke@435 | 671 | _scan_cur_or_nonheap, |
duke@435 | 672 | _scan_older); |
duke@435 | 673 | } while (!_gch->no_allocs_since_save_marks(_level)); |
duke@435 | 674 | } |
duke@435 | 675 | |
duke@435 | 676 | |
duke@435 | 677 | bool ParNewGeneration::_avoid_promotion_undo = false; |
duke@435 | 678 | |
duke@435 | 679 | void ParNewGeneration::adjust_desired_tenuring_threshold() { |
duke@435 | 680 | // Set the desired survivor size to half the real survivor space |
duke@435 | 681 | _tenuring_threshold = |
duke@435 | 682 | age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); |
duke@435 | 683 | } |
duke@435 | 684 | |
duke@435 | 685 | // A Generation that does parallel young-gen collection. |
duke@435 | 686 | |
duke@435 | 687 | void ParNewGeneration::collect(bool full, |
duke@435 | 688 | bool clear_all_soft_refs, |
duke@435 | 689 | size_t size, |
duke@435 | 690 | bool is_tlab) { |
duke@435 | 691 | assert(full || size > 0, "otherwise we don't want to collect"); |
duke@435 | 692 | GenCollectedHeap* gch = GenCollectedHeap::heap(); |
duke@435 | 693 | assert(gch->kind() == CollectedHeap::GenCollectedHeap, |
duke@435 | 694 | "not a CMS generational heap"); |
duke@435 | 695 | AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); |
duke@435 | 696 | WorkGang* workers = gch->workers(); |
duke@435 | 697 | _next_gen = gch->next_gen(this); |
duke@435 | 698 | assert(_next_gen != NULL, |
duke@435 | 699 | "This must be the youngest gen, and not the only gen"); |
duke@435 | 700 | assert(gch->n_gens() == 2, |
duke@435 | 701 | "Par collection currently only works with single older gen."); |
duke@435 | 702 | // Do we have to avoid promotion_undo? |
duke@435 | 703 | if (gch->collector_policy()->is_concurrent_mark_sweep_policy()) { |
duke@435 | 704 | set_avoid_promotion_undo(true); |
duke@435 | 705 | } |
duke@435 | 706 | |
duke@435 | 707 | // If the next generation is too full to accomodate worst-case promotion |
duke@435 | 708 | // from this generation, pass on collection; let the next generation |
duke@435 | 709 | // do it. |
duke@435 | 710 | if (!collection_attempt_is_safe()) { |
duke@435 | 711 | gch->set_incremental_collection_will_fail(); |
duke@435 | 712 | return; |
duke@435 | 713 | } |
duke@435 | 714 | assert(to()->is_empty(), "Else not collection_attempt_is_safe"); |
duke@435 | 715 | |
duke@435 | 716 | init_assuming_no_promotion_failure(); |
duke@435 | 717 | |
duke@435 | 718 | if (UseAdaptiveSizePolicy) { |
duke@435 | 719 | set_survivor_overflow(false); |
duke@435 | 720 | size_policy->minor_collection_begin(); |
duke@435 | 721 | } |
duke@435 | 722 | |
duke@435 | 723 | TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); |
duke@435 | 724 | // Capture heap used before collection (for printing). |
duke@435 | 725 | size_t gch_prev_used = gch->used(); |
duke@435 | 726 | |
duke@435 | 727 | SpecializationStats::clear(); |
duke@435 | 728 | |
duke@435 | 729 | age_table()->clear(); |
jmasa@698 | 730 | to()->clear(SpaceDecorator::Mangle); |
duke@435 | 731 | |
duke@435 | 732 | gch->save_marks(); |
duke@435 | 733 | assert(workers != NULL, "Need parallel worker threads."); |
duke@435 | 734 | ParallelTaskTerminator _term(workers->total_workers(), task_queues()); |
duke@435 | 735 | ParScanThreadStateSet thread_state_set(workers->total_workers(), |
duke@435 | 736 | *to(), *this, *_next_gen, *task_queues(), |
duke@435 | 737 | desired_plab_sz(), _term); |
duke@435 | 738 | |
duke@435 | 739 | ParNewGenTask tsk(this, _next_gen, reserved().end(), &thread_state_set); |
duke@435 | 740 | int n_workers = workers->total_workers(); |
duke@435 | 741 | gch->set_par_threads(n_workers); |
duke@435 | 742 | gch->change_strong_roots_parity(); |
duke@435 | 743 | gch->rem_set()->prepare_for_younger_refs_iterate(true); |
duke@435 | 744 | // It turns out that even when we're using 1 thread, doing the work in a |
duke@435 | 745 | // separate thread causes wide variance in run times. We can't help this |
duke@435 | 746 | // in the multi-threaded case, but we special-case n=1 here to get |
duke@435 | 747 | // repeatable measurements of the 1-thread overhead of the parallel code. |
duke@435 | 748 | if (n_workers > 1) { |
duke@435 | 749 | workers->run_task(&tsk); |
duke@435 | 750 | } else { |
duke@435 | 751 | tsk.work(0); |
duke@435 | 752 | } |
duke@435 | 753 | thread_state_set.reset(); |
duke@435 | 754 | |
duke@435 | 755 | if (PAR_STATS_ENABLED && ParallelGCVerbose) { |
duke@435 | 756 | gclog_or_tty->print("Thread totals:\n" |
duke@435 | 757 | " Pushes: %7d Pops: %7d Steals %7d (sum = %7d).\n", |
duke@435 | 758 | thread_state_set.pushes(), thread_state_set.pops(), |
duke@435 | 759 | thread_state_set.steals(), |
duke@435 | 760 | thread_state_set.pops()+thread_state_set.steals()); |
duke@435 | 761 | } |
duke@435 | 762 | assert(thread_state_set.pushes() == thread_state_set.pops() + thread_state_set.steals(), |
duke@435 | 763 | "Or else the queues are leaky."); |
duke@435 | 764 | |
duke@435 | 765 | // For now, process discovered weak refs sequentially. |
duke@435 | 766 | #ifdef COMPILER2 |
duke@435 | 767 | ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy(); |
duke@435 | 768 | #else |
duke@435 | 769 | ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy(); |
duke@435 | 770 | #endif // COMPILER2 |
duke@435 | 771 | |
duke@435 | 772 | // Process (weak) reference objects found during scavenge. |
duke@435 | 773 | IsAliveClosure is_alive(this); |
duke@435 | 774 | ScanWeakRefClosure scan_weak_ref(this); |
duke@435 | 775 | KeepAliveClosure keep_alive(&scan_weak_ref); |
duke@435 | 776 | ScanClosure scan_without_gc_barrier(this, false); |
duke@435 | 777 | ScanClosureWithParBarrier scan_with_gc_barrier(this, true); |
duke@435 | 778 | set_promo_failure_scan_stack_closure(&scan_without_gc_barrier); |
duke@435 | 779 | EvacuateFollowersClosureGeneral evacuate_followers(gch, _level, |
duke@435 | 780 | &scan_without_gc_barrier, &scan_with_gc_barrier); |
duke@435 | 781 | if (ref_processor()->processing_is_mt()) { |
duke@435 | 782 | ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
duke@435 | 783 | ref_processor()->process_discovered_references( |
duke@435 | 784 | soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, |
duke@435 | 785 | &task_executor); |
duke@435 | 786 | } else { |
duke@435 | 787 | thread_state_set.flush(); |
duke@435 | 788 | gch->set_par_threads(0); // 0 ==> non-parallel. |
duke@435 | 789 | gch->save_marks(); |
duke@435 | 790 | ref_processor()->process_discovered_references( |
duke@435 | 791 | soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, |
duke@435 | 792 | NULL); |
duke@435 | 793 | } |
duke@435 | 794 | if (!promotion_failed()) { |
duke@435 | 795 | // Swap the survivor spaces. |
jmasa@698 | 796 | eden()->clear(SpaceDecorator::Mangle); |
jmasa@698 | 797 | from()->clear(SpaceDecorator::Mangle); |
jmasa@698 | 798 | if (ZapUnusedHeapArea) { |
jmasa@698 | 799 | // This is now done here because of the piece-meal mangling which |
jmasa@698 | 800 | // can check for valid mangling at intermediate points in the |
jmasa@698 | 801 | // collection(s). When a minor collection fails to collect |
jmasa@698 | 802 | // sufficient space resizing of the young generation can occur |
jmasa@698 | 803 | // an redistribute the spaces in the young generation. Mangle |
jmasa@698 | 804 | // here so that unzapped regions don't get distributed to |
jmasa@698 | 805 | // other spaces. |
jmasa@698 | 806 | to()->mangle_unused_area(); |
jmasa@698 | 807 | } |
duke@435 | 808 | swap_spaces(); |
duke@435 | 809 | |
duke@435 | 810 | assert(to()->is_empty(), "to space should be empty now"); |
duke@435 | 811 | } else { |
duke@435 | 812 | assert(HandlePromotionFailure, |
duke@435 | 813 | "Should only be here if promotion failure handling is on"); |
duke@435 | 814 | if (_promo_failure_scan_stack != NULL) { |
duke@435 | 815 | // Can be non-null because of reference processing. |
duke@435 | 816 | // Free stack with its elements. |
duke@435 | 817 | delete _promo_failure_scan_stack; |
duke@435 | 818 | _promo_failure_scan_stack = NULL; |
duke@435 | 819 | } |
duke@435 | 820 | remove_forwarding_pointers(); |
duke@435 | 821 | if (PrintGCDetails) { |
duke@435 | 822 | gclog_or_tty->print(" (promotion failed)"); |
duke@435 | 823 | } |
duke@435 | 824 | // All the spaces are in play for mark-sweep. |
duke@435 | 825 | swap_spaces(); // Make life simpler for CMS || rescan; see 6483690. |
duke@435 | 826 | from()->set_next_compaction_space(to()); |
duke@435 | 827 | gch->set_incremental_collection_will_fail(); |
jmasa@441 | 828 | |
jmasa@441 | 829 | // Reset the PromotionFailureALot counters. |
jmasa@441 | 830 | NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) |
duke@435 | 831 | } |
duke@435 | 832 | // set new iteration safe limit for the survivor spaces |
duke@435 | 833 | from()->set_concurrent_iteration_safe_limit(from()->top()); |
duke@435 | 834 | to()->set_concurrent_iteration_safe_limit(to()->top()); |
duke@435 | 835 | |
duke@435 | 836 | adjust_desired_tenuring_threshold(); |
duke@435 | 837 | if (ResizePLAB) { |
duke@435 | 838 | plab_stats()->adjust_desired_plab_sz(); |
duke@435 | 839 | } |
duke@435 | 840 | |
duke@435 | 841 | if (PrintGC && !PrintGCDetails) { |
duke@435 | 842 | gch->print_heap_change(gch_prev_used); |
duke@435 | 843 | } |
duke@435 | 844 | |
duke@435 | 845 | if (UseAdaptiveSizePolicy) { |
duke@435 | 846 | size_policy->minor_collection_end(gch->gc_cause()); |
duke@435 | 847 | size_policy->avg_survived()->sample(from()->used()); |
duke@435 | 848 | } |
duke@435 | 849 | |
duke@435 | 850 | update_time_of_last_gc(os::javaTimeMillis()); |
duke@435 | 851 | |
duke@435 | 852 | SpecializationStats::print(); |
duke@435 | 853 | |
duke@435 | 854 | ref_processor()->set_enqueuing_is_done(true); |
duke@435 | 855 | if (ref_processor()->processing_is_mt()) { |
duke@435 | 856 | ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
duke@435 | 857 | ref_processor()->enqueue_discovered_references(&task_executor); |
duke@435 | 858 | } else { |
duke@435 | 859 | ref_processor()->enqueue_discovered_references(NULL); |
duke@435 | 860 | } |
duke@435 | 861 | ref_processor()->verify_no_references_recorded(); |
duke@435 | 862 | } |
duke@435 | 863 | |
duke@435 | 864 | static int sum; |
duke@435 | 865 | void ParNewGeneration::waste_some_time() { |
duke@435 | 866 | for (int i = 0; i < 100; i++) { |
duke@435 | 867 | sum += i; |
duke@435 | 868 | } |
duke@435 | 869 | } |
duke@435 | 870 | |
duke@435 | 871 | static const oop ClaimedForwardPtr = oop(0x4); |
duke@435 | 872 | |
duke@435 | 873 | // Because of concurrency, there are times where an object for which |
duke@435 | 874 | // "is_forwarded()" is true contains an "interim" forwarding pointer |
duke@435 | 875 | // value. Such a value will soon be overwritten with a real value. |
duke@435 | 876 | // This method requires "obj" to have a forwarding pointer, and waits, if |
duke@435 | 877 | // necessary for a real one to be inserted, and returns it. |
duke@435 | 878 | |
duke@435 | 879 | oop ParNewGeneration::real_forwardee(oop obj) { |
duke@435 | 880 | oop forward_ptr = obj->forwardee(); |
duke@435 | 881 | if (forward_ptr != ClaimedForwardPtr) { |
duke@435 | 882 | return forward_ptr; |
duke@435 | 883 | } else { |
duke@435 | 884 | return real_forwardee_slow(obj); |
duke@435 | 885 | } |
duke@435 | 886 | } |
duke@435 | 887 | |
duke@435 | 888 | oop ParNewGeneration::real_forwardee_slow(oop obj) { |
duke@435 | 889 | // Spin-read if it is claimed but not yet written by another thread. |
duke@435 | 890 | oop forward_ptr = obj->forwardee(); |
duke@435 | 891 | while (forward_ptr == ClaimedForwardPtr) { |
duke@435 | 892 | waste_some_time(); |
duke@435 | 893 | assert(obj->is_forwarded(), "precondition"); |
duke@435 | 894 | forward_ptr = obj->forwardee(); |
duke@435 | 895 | } |
duke@435 | 896 | return forward_ptr; |
duke@435 | 897 | } |
duke@435 | 898 | |
duke@435 | 899 | #ifdef ASSERT |
duke@435 | 900 | bool ParNewGeneration::is_legal_forward_ptr(oop p) { |
duke@435 | 901 | return |
duke@435 | 902 | (_avoid_promotion_undo && p == ClaimedForwardPtr) |
duke@435 | 903 | || Universe::heap()->is_in_reserved(p); |
duke@435 | 904 | } |
duke@435 | 905 | #endif |
duke@435 | 906 | |
duke@435 | 907 | void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { |
duke@435 | 908 | if ((m != markOopDesc::prototype()) && |
duke@435 | 909 | (!UseBiasedLocking || (m != markOopDesc::biased_locking_prototype()))) { |
duke@435 | 910 | MutexLocker ml(ParGCRareEvent_lock); |
duke@435 | 911 | DefNewGeneration::preserve_mark_if_necessary(obj, m); |
duke@435 | 912 | } |
duke@435 | 913 | } |
duke@435 | 914 | |
duke@435 | 915 | // Multiple GC threads may try to promote an object. If the object |
duke@435 | 916 | // is successfully promoted, a forwarding pointer will be installed in |
duke@435 | 917 | // the object in the young generation. This method claims the right |
duke@435 | 918 | // to install the forwarding pointer before it copies the object, |
duke@435 | 919 | // thus avoiding the need to undo the copy as in |
duke@435 | 920 | // copy_to_survivor_space_avoiding_with_undo. |
duke@435 | 921 | |
duke@435 | 922 | oop ParNewGeneration::copy_to_survivor_space_avoiding_promotion_undo( |
duke@435 | 923 | ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { |
duke@435 | 924 | // In the sequential version, this assert also says that the object is |
duke@435 | 925 | // not forwarded. That might not be the case here. It is the case that |
duke@435 | 926 | // the caller observed it to be not forwarded at some time in the past. |
duke@435 | 927 | assert(is_in_reserved(old), "shouldn't be scavenging this oop"); |
duke@435 | 928 | |
duke@435 | 929 | // The sequential code read "old->age()" below. That doesn't work here, |
duke@435 | 930 | // since the age is in the mark word, and that might be overwritten with |
duke@435 | 931 | // a forwarding pointer by a parallel thread. So we must save the mark |
duke@435 | 932 | // word in a local and then analyze it. |
duke@435 | 933 | oopDesc dummyOld; |
duke@435 | 934 | dummyOld.set_mark(m); |
duke@435 | 935 | assert(!dummyOld.is_forwarded(), |
duke@435 | 936 | "should not be called with forwarding pointer mark word."); |
duke@435 | 937 | |
duke@435 | 938 | oop new_obj = NULL; |
duke@435 | 939 | oop forward_ptr; |
duke@435 | 940 | |
duke@435 | 941 | // Try allocating obj in to-space (unless too old) |
duke@435 | 942 | if (dummyOld.age() < tenuring_threshold()) { |
duke@435 | 943 | new_obj = (oop)par_scan_state->alloc_in_to_space(sz); |
duke@435 | 944 | if (new_obj == NULL) { |
duke@435 | 945 | set_survivor_overflow(true); |
duke@435 | 946 | } |
duke@435 | 947 | } |
duke@435 | 948 | |
duke@435 | 949 | if (new_obj == NULL) { |
duke@435 | 950 | // Either to-space is full or we decided to promote |
duke@435 | 951 | // try allocating obj tenured |
duke@435 | 952 | |
duke@435 | 953 | // Attempt to install a null forwarding pointer (atomically), |
duke@435 | 954 | // to claim the right to install the real forwarding pointer. |
duke@435 | 955 | forward_ptr = old->forward_to_atomic(ClaimedForwardPtr); |
duke@435 | 956 | if (forward_ptr != NULL) { |
duke@435 | 957 | // someone else beat us to it. |
duke@435 | 958 | return real_forwardee(old); |
duke@435 | 959 | } |
duke@435 | 960 | |
duke@435 | 961 | new_obj = _next_gen->par_promote(par_scan_state->thread_num(), |
duke@435 | 962 | old, m, sz); |
duke@435 | 963 | |
duke@435 | 964 | if (new_obj == NULL) { |
duke@435 | 965 | if (!HandlePromotionFailure) { |
duke@435 | 966 | // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag |
duke@435 | 967 | // is incorrectly set. In any case, its seriously wrong to be here! |
duke@435 | 968 | vm_exit_out_of_memory(sz*wordSize, "promotion"); |
duke@435 | 969 | } |
duke@435 | 970 | // promotion failed, forward to self |
duke@435 | 971 | _promotion_failed = true; |
duke@435 | 972 | new_obj = old; |
duke@435 | 973 | |
duke@435 | 974 | preserve_mark_if_necessary(old, m); |
duke@435 | 975 | } |
duke@435 | 976 | |
duke@435 | 977 | old->forward_to(new_obj); |
duke@435 | 978 | forward_ptr = NULL; |
duke@435 | 979 | } else { |
duke@435 | 980 | // Is in to-space; do copying ourselves. |
duke@435 | 981 | Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); |
duke@435 | 982 | forward_ptr = old->forward_to_atomic(new_obj); |
duke@435 | 983 | // Restore the mark word copied above. |
duke@435 | 984 | new_obj->set_mark(m); |
duke@435 | 985 | // Increment age if obj still in new generation |
duke@435 | 986 | new_obj->incr_age(); |
duke@435 | 987 | par_scan_state->age_table()->add(new_obj, sz); |
duke@435 | 988 | } |
duke@435 | 989 | assert(new_obj != NULL, "just checking"); |
duke@435 | 990 | |
duke@435 | 991 | if (forward_ptr == NULL) { |
duke@435 | 992 | oop obj_to_push = new_obj; |
duke@435 | 993 | if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { |
duke@435 | 994 | // Length field used as index of next element to be scanned. |
duke@435 | 995 | // Real length can be obtained from real_forwardee() |
duke@435 | 996 | arrayOop(old)->set_length(0); |
duke@435 | 997 | obj_to_push = old; |
duke@435 | 998 | assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, |
duke@435 | 999 | "push forwarded object"); |
duke@435 | 1000 | } |
duke@435 | 1001 | // Push it on one of the queues of to-be-scanned objects. |
duke@435 | 1002 | if (!par_scan_state->work_queue()->push(obj_to_push)) { |
duke@435 | 1003 | // Add stats for overflow pushes. |
duke@435 | 1004 | if (Verbose && PrintGCDetails) { |
duke@435 | 1005 | gclog_or_tty->print("queue overflow!\n"); |
duke@435 | 1006 | } |
duke@435 | 1007 | push_on_overflow_list(old); |
duke@435 | 1008 | par_scan_state->note_overflow_push(); |
duke@435 | 1009 | } |
duke@435 | 1010 | par_scan_state->note_push(); |
duke@435 | 1011 | |
duke@435 | 1012 | return new_obj; |
duke@435 | 1013 | } |
duke@435 | 1014 | |
duke@435 | 1015 | // Oops. Someone beat us to it. Undo the allocation. Where did we |
duke@435 | 1016 | // allocate it? |
duke@435 | 1017 | if (is_in_reserved(new_obj)) { |
duke@435 | 1018 | // Must be in to_space. |
duke@435 | 1019 | assert(to()->is_in_reserved(new_obj), "Checking"); |
duke@435 | 1020 | if (forward_ptr == ClaimedForwardPtr) { |
duke@435 | 1021 | // Wait to get the real forwarding pointer value. |
duke@435 | 1022 | forward_ptr = real_forwardee(old); |
duke@435 | 1023 | } |
duke@435 | 1024 | par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); |
duke@435 | 1025 | } |
duke@435 | 1026 | |
duke@435 | 1027 | return forward_ptr; |
duke@435 | 1028 | } |
duke@435 | 1029 | |
duke@435 | 1030 | |
duke@435 | 1031 | // Multiple GC threads may try to promote the same object. If two |
duke@435 | 1032 | // or more GC threads copy the object, only one wins the race to install |
duke@435 | 1033 | // the forwarding pointer. The other threads have to undo their copy. |
duke@435 | 1034 | |
duke@435 | 1035 | oop ParNewGeneration::copy_to_survivor_space_with_undo( |
duke@435 | 1036 | ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { |
duke@435 | 1037 | |
duke@435 | 1038 | // In the sequential version, this assert also says that the object is |
duke@435 | 1039 | // not forwarded. That might not be the case here. It is the case that |
duke@435 | 1040 | // the caller observed it to be not forwarded at some time in the past. |
duke@435 | 1041 | assert(is_in_reserved(old), "shouldn't be scavenging this oop"); |
duke@435 | 1042 | |
duke@435 | 1043 | // The sequential code read "old->age()" below. That doesn't work here, |
duke@435 | 1044 | // since the age is in the mark word, and that might be overwritten with |
duke@435 | 1045 | // a forwarding pointer by a parallel thread. So we must save the mark |
duke@435 | 1046 | // word here, install it in a local oopDesc, and then analyze it. |
duke@435 | 1047 | oopDesc dummyOld; |
duke@435 | 1048 | dummyOld.set_mark(m); |
duke@435 | 1049 | assert(!dummyOld.is_forwarded(), |
duke@435 | 1050 | "should not be called with forwarding pointer mark word."); |
duke@435 | 1051 | |
duke@435 | 1052 | bool failed_to_promote = false; |
duke@435 | 1053 | oop new_obj = NULL; |
duke@435 | 1054 | oop forward_ptr; |
duke@435 | 1055 | |
duke@435 | 1056 | // Try allocating obj in to-space (unless too old) |
duke@435 | 1057 | if (dummyOld.age() < tenuring_threshold()) { |
duke@435 | 1058 | new_obj = (oop)par_scan_state->alloc_in_to_space(sz); |
duke@435 | 1059 | if (new_obj == NULL) { |
duke@435 | 1060 | set_survivor_overflow(true); |
duke@435 | 1061 | } |
duke@435 | 1062 | } |
duke@435 | 1063 | |
duke@435 | 1064 | if (new_obj == NULL) { |
duke@435 | 1065 | // Either to-space is full or we decided to promote |
duke@435 | 1066 | // try allocating obj tenured |
duke@435 | 1067 | new_obj = _next_gen->par_promote(par_scan_state->thread_num(), |
duke@435 | 1068 | old, m, sz); |
duke@435 | 1069 | |
duke@435 | 1070 | if (new_obj == NULL) { |
duke@435 | 1071 | if (!HandlePromotionFailure) { |
duke@435 | 1072 | // A failed promotion likely means the MaxLiveObjectEvacuationRatio |
duke@435 | 1073 | // flag is incorrectly set. In any case, its seriously wrong to be |
duke@435 | 1074 | // here! |
duke@435 | 1075 | vm_exit_out_of_memory(sz*wordSize, "promotion"); |
duke@435 | 1076 | } |
duke@435 | 1077 | // promotion failed, forward to self |
duke@435 | 1078 | forward_ptr = old->forward_to_atomic(old); |
duke@435 | 1079 | new_obj = old; |
duke@435 | 1080 | |
duke@435 | 1081 | if (forward_ptr != NULL) { |
duke@435 | 1082 | return forward_ptr; // someone else succeeded |
duke@435 | 1083 | } |
duke@435 | 1084 | |
duke@435 | 1085 | _promotion_failed = true; |
duke@435 | 1086 | failed_to_promote = true; |
duke@435 | 1087 | |
duke@435 | 1088 | preserve_mark_if_necessary(old, m); |
duke@435 | 1089 | } |
duke@435 | 1090 | } else { |
duke@435 | 1091 | // Is in to-space; do copying ourselves. |
duke@435 | 1092 | Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); |
duke@435 | 1093 | // Restore the mark word copied above. |
duke@435 | 1094 | new_obj->set_mark(m); |
duke@435 | 1095 | // Increment age if new_obj still in new generation |
duke@435 | 1096 | new_obj->incr_age(); |
duke@435 | 1097 | par_scan_state->age_table()->add(new_obj, sz); |
duke@435 | 1098 | } |
duke@435 | 1099 | assert(new_obj != NULL, "just checking"); |
duke@435 | 1100 | |
duke@435 | 1101 | // Now attempt to install the forwarding pointer (atomically). |
duke@435 | 1102 | // We have to copy the mark word before overwriting with forwarding |
duke@435 | 1103 | // ptr, so we can restore it below in the copy. |
duke@435 | 1104 | if (!failed_to_promote) { |
duke@435 | 1105 | forward_ptr = old->forward_to_atomic(new_obj); |
duke@435 | 1106 | } |
duke@435 | 1107 | |
duke@435 | 1108 | if (forward_ptr == NULL) { |
duke@435 | 1109 | oop obj_to_push = new_obj; |
duke@435 | 1110 | if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { |
duke@435 | 1111 | // Length field used as index of next element to be scanned. |
duke@435 | 1112 | // Real length can be obtained from real_forwardee() |
duke@435 | 1113 | arrayOop(old)->set_length(0); |
duke@435 | 1114 | obj_to_push = old; |
duke@435 | 1115 | assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, |
duke@435 | 1116 | "push forwarded object"); |
duke@435 | 1117 | } |
duke@435 | 1118 | // Push it on one of the queues of to-be-scanned objects. |
duke@435 | 1119 | if (!par_scan_state->work_queue()->push(obj_to_push)) { |
duke@435 | 1120 | // Add stats for overflow pushes. |
duke@435 | 1121 | push_on_overflow_list(old); |
duke@435 | 1122 | par_scan_state->note_overflow_push(); |
duke@435 | 1123 | } |
duke@435 | 1124 | par_scan_state->note_push(); |
duke@435 | 1125 | |
duke@435 | 1126 | return new_obj; |
duke@435 | 1127 | } |
duke@435 | 1128 | |
duke@435 | 1129 | // Oops. Someone beat us to it. Undo the allocation. Where did we |
duke@435 | 1130 | // allocate it? |
duke@435 | 1131 | if (is_in_reserved(new_obj)) { |
duke@435 | 1132 | // Must be in to_space. |
duke@435 | 1133 | assert(to()->is_in_reserved(new_obj), "Checking"); |
duke@435 | 1134 | par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); |
duke@435 | 1135 | } else { |
duke@435 | 1136 | assert(!_avoid_promotion_undo, "Should not be here if avoiding."); |
duke@435 | 1137 | _next_gen->par_promote_alloc_undo(par_scan_state->thread_num(), |
duke@435 | 1138 | (HeapWord*)new_obj, sz); |
duke@435 | 1139 | } |
duke@435 | 1140 | |
duke@435 | 1141 | return forward_ptr; |
duke@435 | 1142 | } |
duke@435 | 1143 | |
duke@435 | 1144 | void ParNewGeneration::push_on_overflow_list(oop from_space_obj) { |
duke@435 | 1145 | oop cur_overflow_list = _overflow_list; |
duke@435 | 1146 | // if the object has been forwarded to itself, then we cannot |
duke@435 | 1147 | // use the klass pointer for the linked list. Instead we have |
duke@435 | 1148 | // to allocate an oopDesc in the C-Heap and use that for the linked list. |
duke@435 | 1149 | if (from_space_obj->forwardee() == from_space_obj) { |
duke@435 | 1150 | oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1); |
duke@435 | 1151 | listhead->forward_to(from_space_obj); |
duke@435 | 1152 | from_space_obj = listhead; |
duke@435 | 1153 | } |
duke@435 | 1154 | while (true) { |
duke@435 | 1155 | from_space_obj->set_klass_to_list_ptr(cur_overflow_list); |
duke@435 | 1156 | oop observed_overflow_list = |
duke@435 | 1157 | (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); |
duke@435 | 1158 | if (observed_overflow_list == cur_overflow_list) break; |
duke@435 | 1159 | // Otherwise... |
duke@435 | 1160 | cur_overflow_list = observed_overflow_list; |
duke@435 | 1161 | } |
duke@435 | 1162 | } |
duke@435 | 1163 | |
duke@435 | 1164 | bool |
duke@435 | 1165 | ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { |
duke@435 | 1166 | ObjToScanQueue* work_q = par_scan_state->work_queue(); |
duke@435 | 1167 | // How many to take? |
duke@435 | 1168 | int objsFromOverflow = MIN2(work_q->max_elems()/4, |
duke@435 | 1169 | (juint)ParGCDesiredObjsFromOverflowList); |
duke@435 | 1170 | |
duke@435 | 1171 | if (_overflow_list == NULL) return false; |
duke@435 | 1172 | |
duke@435 | 1173 | // Otherwise, there was something there; try claiming the list. |
duke@435 | 1174 | oop prefix = (oop)Atomic::xchg_ptr(NULL, &_overflow_list); |
duke@435 | 1175 | |
duke@435 | 1176 | if (prefix == NULL) { |
duke@435 | 1177 | return false; |
duke@435 | 1178 | } |
duke@435 | 1179 | // Trim off a prefix of at most objsFromOverflow items |
duke@435 | 1180 | int i = 1; |
duke@435 | 1181 | oop cur = prefix; |
coleenp@602 | 1182 | while (i < objsFromOverflow && cur->klass_or_null() != NULL) { |
duke@435 | 1183 | i++; cur = oop(cur->klass()); |
duke@435 | 1184 | } |
duke@435 | 1185 | |
duke@435 | 1186 | // Reattach remaining (suffix) to overflow list |
coleenp@602 | 1187 | if (cur->klass_or_null() != NULL) { |
duke@435 | 1188 | oop suffix = oop(cur->klass()); |
duke@435 | 1189 | cur->set_klass_to_list_ptr(NULL); |
duke@435 | 1190 | |
duke@435 | 1191 | // Find last item of suffix list |
duke@435 | 1192 | oop last = suffix; |
coleenp@602 | 1193 | while (last->klass_or_null() != NULL) { |
duke@435 | 1194 | last = oop(last->klass()); |
duke@435 | 1195 | } |
duke@435 | 1196 | // Atomically prepend suffix to current overflow list |
duke@435 | 1197 | oop cur_overflow_list = _overflow_list; |
duke@435 | 1198 | while (true) { |
duke@435 | 1199 | last->set_klass_to_list_ptr(cur_overflow_list); |
duke@435 | 1200 | oop observed_overflow_list = |
duke@435 | 1201 | (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); |
duke@435 | 1202 | if (observed_overflow_list == cur_overflow_list) break; |
duke@435 | 1203 | // Otherwise... |
duke@435 | 1204 | cur_overflow_list = observed_overflow_list; |
duke@435 | 1205 | } |
duke@435 | 1206 | } |
duke@435 | 1207 | |
duke@435 | 1208 | // Push objects on prefix list onto this thread's work queue |
duke@435 | 1209 | assert(cur != NULL, "program logic"); |
duke@435 | 1210 | cur = prefix; |
duke@435 | 1211 | int n = 0; |
duke@435 | 1212 | while (cur != NULL) { |
duke@435 | 1213 | oop obj_to_push = cur->forwardee(); |
duke@435 | 1214 | oop next = oop(cur->klass()); |
duke@435 | 1215 | cur->set_klass(obj_to_push->klass()); |
duke@435 | 1216 | if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { |
duke@435 | 1217 | obj_to_push = cur; |
duke@435 | 1218 | assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
duke@435 | 1219 | } |
duke@435 | 1220 | work_q->push(obj_to_push); |
duke@435 | 1221 | cur = next; |
duke@435 | 1222 | n++; |
duke@435 | 1223 | } |
duke@435 | 1224 | par_scan_state->note_overflow_refill(n); |
duke@435 | 1225 | return true; |
duke@435 | 1226 | } |
duke@435 | 1227 | |
duke@435 | 1228 | void ParNewGeneration::ref_processor_init() |
duke@435 | 1229 | { |
duke@435 | 1230 | if (_ref_processor == NULL) { |
duke@435 | 1231 | // Allocate and initialize a reference processor |
duke@435 | 1232 | _ref_processor = ReferenceProcessor::create_ref_processor( |
duke@435 | 1233 | _reserved, // span |
duke@435 | 1234 | refs_discovery_is_atomic(), // atomic_discovery |
duke@435 | 1235 | refs_discovery_is_mt(), // mt_discovery |
duke@435 | 1236 | NULL, // is_alive_non_header |
duke@435 | 1237 | ParallelGCThreads, |
duke@435 | 1238 | ParallelRefProcEnabled); |
duke@435 | 1239 | } |
duke@435 | 1240 | } |
duke@435 | 1241 | |
duke@435 | 1242 | const char* ParNewGeneration::name() const { |
duke@435 | 1243 | return "par new generation"; |
duke@435 | 1244 | } |