1 /* 2 * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc/g1/g1Allocator.inline.hpp" 27 #include "gc/g1/g1CollectedHeap.inline.hpp" 28 #include "gc/g1/g1CollectionSet.hpp" 29 #include "gc/g1/g1OopClosures.inline.hpp" 30 #include "gc/g1/g1ParScanThreadState.inline.hpp" 31 #include "gc/g1/g1RootClosures.hpp" 32 #include "gc/g1/g1StringDedup.hpp" 33 #include "gc/shared/gcTrace.hpp" 34 #include "gc/shared/taskqueue.inline.hpp" 35 #include "memory/allocation.inline.hpp" 36 #include "oops/access.inline.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "runtime/prefetch.inline.hpp" 39 40 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length) 41 : _g1h(g1h), 42 _refs(g1h->task_queue(worker_id)), 43 _dcq(&g1h->dirty_card_queue_set()), 44 _ct(g1h->card_table()), 45 _closures(NULL), 46 _plab_allocator(NULL), 47 _age_table(false), 48 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 49 _scanner(g1h, this), 50 _worker_id(worker_id), 51 _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1), 52 _stack_trim_lower_threshold(GCDrainStackTargetSize), 53 _trim_ticks(), 54 _old_gen_is_full(false) 55 { 56 // we allocate G1YoungSurvRateNumRegions plus one entries, since 57 // we "sacrifice" entry 0 to keep track of surviving bytes for 58 // non-young regions (where the age is -1) 59 // We also add a few elements at the beginning and at the end in 60 // an attempt to eliminate cache contention 61 size_t real_length = 1 + young_cset_length; 62 size_t array_length = PADDING_ELEM_NUM + 63 real_length + 64 PADDING_ELEM_NUM; 65 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 66 if (_surviving_young_words_base == NULL) 67 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 68 "Not enough space for young surv histo."); 69 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 70 memset(_surviving_young_words, 0, real_length * sizeof(size_t)); 71 72 _plab_allocator = new G1PLABAllocator(_g1h->allocator()); 73 74 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 75 // The dest for Young is used when the objects are aged enough to 76 // need to be moved to the next space. 77 _dest[InCSetState::Young] = InCSetState::Old; 78 _dest[InCSetState::Old] = InCSetState::Old; 79 80 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); 81 } 82 83 // Pass locally gathered statistics to global state. 84 void G1ParScanThreadState::flush(size_t* surviving_young_words) { 85 _dcq.flush(); 86 // Update allocation statistics. 87 _plab_allocator->flush_and_retire_stats(); 88 _g1h->g1_policy()->record_age_table(&_age_table); 89 90 uint length = _g1h->collection_set()->young_region_length(); 91 for (uint region_index = 0; region_index < length; region_index++) { 92 surviving_young_words[region_index] += _surviving_young_words[region_index]; 93 } 94 } 95 96 G1ParScanThreadState::~G1ParScanThreadState() { 97 delete _plab_allocator; 98 delete _closures; 99 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 100 } 101 102 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) { 103 _plab_allocator->waste(wasted, undo_wasted); 104 } 105 106 #ifdef ASSERT 107 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 108 assert(ref != NULL, "invariant"); 109 assert(UseCompressedOops, "sanity"); 110 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref)); 111 oop p = RawAccess<>::oop_load(ref); 112 assert(_g1h->is_in_g1_reserved(p), 113 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 114 return true; 115 } 116 117 bool G1ParScanThreadState::verify_ref(oop* ref) const { 118 assert(ref != NULL, "invariant"); 119 if (has_partial_array_mask(ref)) { 120 // Must be in the collection set--it's already been copied. 121 oop p = clear_partial_array_mask(ref); 122 assert(_g1h->is_in_cset(p), 123 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 124 } else { 125 oop p = RawAccess<>::oop_load(ref); 126 assert(_g1h->is_in_g1_reserved(p), 127 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 128 } 129 return true; 130 } 131 132 bool G1ParScanThreadState::verify_task(StarTask ref) const { 133 if (ref.is_narrow()) { 134 return verify_ref((narrowOop*) ref); 135 } else { 136 return verify_ref((oop*) ref); 137 } 138 } 139 #endif // ASSERT 140 141 void G1ParScanThreadState::trim_queue() { 142 StarTask ref; 143 do { 144 // Fully drain the queue. 145 trim_queue_to_threshold(0); 146 } while (!_refs->is_empty()); 147 } 148 149 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 150 InCSetState* dest, 151 size_t word_sz, 152 bool previous_plab_refill_failed) { 153 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value()); 154 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 155 156 // Right now we only have two types of regions (young / old) so 157 // let's keep the logic here simple. We can generalize it when necessary. 158 if (dest->is_young()) { 159 bool plab_refill_in_old_failed = false; 160 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old, 161 word_sz, 162 &plab_refill_in_old_failed); 163 // Make sure that we won't attempt to copy any other objects out 164 // of a survivor region (given that apparently we cannot allocate 165 // any new ones) to avoid coming into this slow path again and again. 166 // Only consider failed PLAB refill here: failed inline allocations are 167 // typically large, so not indicative of remaining space. 168 if (previous_plab_refill_failed) { 169 _tenuring_threshold = 0; 170 } 171 172 if (obj_ptr != NULL) { 173 dest->set_old(); 174 } else { 175 // We just failed to allocate in old gen. The same idea as explained above 176 // for making survivor gen unavailable for allocation applies for old gen. 177 _old_gen_is_full = plab_refill_in_old_failed; 178 } 179 return obj_ptr; 180 } else { 181 _old_gen_is_full = previous_plab_refill_failed; 182 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 183 // no other space to try. 184 return NULL; 185 } 186 } 187 188 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 189 if (state.is_young()) { 190 age = !m->has_displaced_mark_helper() ? m->age() 191 : m->displaced_mark_helper()->age(); 192 if (age < _tenuring_threshold) { 193 return state; 194 } 195 } 196 return dest(state); 197 } 198 199 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state, 200 oop const old, size_t word_sz, uint age, 201 HeapWord * const obj_ptr) const { 202 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state); 203 if (alloc_buf->contains(obj_ptr)) { 204 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age, 205 dest_state.value() == InCSetState::Old, 206 alloc_buf->word_sz() * HeapWordSize); 207 } else { 208 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age, 209 dest_state.value() == InCSetState::Old); 210 } 211 } 212 213 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 214 oop const old, 215 markOop const old_mark) { 216 const size_t word_sz = old->size(); 217 HeapRegion* const from_region = _g1h->heap_region_containing(old); 218 // +1 to make the -1 indexes valid... 219 const int young_index = from_region->young_index_in_cset()+1; 220 assert( (from_region->is_young() && young_index > 0) || 221 (!from_region->is_young() && young_index == 0), "invariant" ); 222 223 uint age = 0; 224 InCSetState dest_state = next_state(state, old_mark, age); 225 // The second clause is to prevent premature evacuation failure in case there 226 // is still space in survivor, but old gen is full. 227 if (_old_gen_is_full && dest_state.is_old()) { 228 return handle_evacuation_failure_par(old, old_mark); 229 } 230 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz); 231 232 // PLAB allocations should succeed most of the time, so we'll 233 // normally check against NULL once and that's it. 234 if (obj_ptr == NULL) { 235 bool plab_refill_failed = false; 236 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed); 237 if (obj_ptr == NULL) { 238 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed); 239 if (obj_ptr == NULL) { 240 // This will either forward-to-self, or detect that someone else has 241 // installed a forwarding pointer. 242 return handle_evacuation_failure_par(old, old_mark); 243 } 244 } 245 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { 246 // The events are checked individually as part of the actual commit 247 report_promotion_event(dest_state, old, word_sz, age, obj_ptr); 248 } 249 } 250 251 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 252 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 253 254 #ifndef PRODUCT 255 // Should this evacuation fail? 256 if (_g1h->evacuation_should_fail()) { 257 // Doing this after all the allocation attempts also tests the 258 // undo_allocation() method too. 259 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 260 return handle_evacuation_failure_par(old, old_mark); 261 } 262 #endif // !PRODUCT 263 264 // We're going to allocate linearly, so might as well prefetch ahead. 265 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 266 267 const oop obj = oop(obj_ptr); 268 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed); 269 if (forward_ptr == NULL) { 270 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 271 272 if (dest_state.is_young()) { 273 if (age < markOopDesc::max_age) { 274 age++; 275 } 276 if (old_mark->has_displaced_mark_helper()) { 277 // In this case, we have to install the mark word first, 278 // otherwise obj looks to be forwarded (the old mark word, 279 // which contains the forward pointer, was copied) 280 obj->set_mark_raw(old_mark); 281 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 282 old_mark->set_displaced_mark_helper(new_mark); 283 } else { 284 obj->set_mark_raw(old_mark->set_age(age)); 285 } 286 _age_table.add(age, word_sz); 287 } else { 288 obj->set_mark_raw(old_mark); 289 } 290 291 if (G1StringDedup::is_enabled()) { 292 const bool is_from_young = state.is_young(); 293 const bool is_to_young = dest_state.is_young(); 294 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(), 295 "sanity"); 296 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), 297 "sanity"); 298 G1StringDedup::enqueue_from_evacuation(is_from_young, 299 is_to_young, 300 _worker_id, 301 obj); 302 } 303 304 _surviving_young_words[young_index] += word_sz; 305 306 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 307 // We keep track of the next start index in the length field of 308 // the to-space object. The actual length can be found in the 309 // length field of the from-space object. 310 arrayOop(obj)->set_length(0); 311 oop* old_p = set_partial_array_mask(old); 312 do_oop_partial_array(old_p); 313 } else { 314 _scanner.set_scanning_in_young(dest_state.is_young()); 315 obj->oop_iterate_backwards(&_scanner); 316 } 317 return obj; 318 } else { 319 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 320 return forward_ptr; 321 } 322 } 323 324 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { 325 assert(worker_id < _n_workers, "out of bounds access"); 326 if (_states[worker_id] == NULL) { 327 _states[worker_id] = new G1ParScanThreadState(_g1h, worker_id, _young_cset_length); 328 } 329 return _states[worker_id]; 330 } 331 332 const size_t* G1ParScanThreadStateSet::surviving_young_words() const { 333 assert(_flushed, "thread local state from the per thread states should have been flushed"); 334 return _surviving_young_words_total; 335 } 336 337 void G1ParScanThreadStateSet::flush() { 338 assert(!_flushed, "thread local state from the per thread states should be flushed once"); 339 340 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 341 G1ParScanThreadState* pss = _states[worker_index]; 342 343 if (pss == NULL) { 344 continue; 345 } 346 347 pss->flush(_surviving_young_words_total); 348 delete pss; 349 _states[worker_index] = NULL; 350 } 351 _flushed = true; 352 } 353 354 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 355 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 356 357 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed); 358 if (forward_ptr == NULL) { 359 // Forward-to-self succeeded. We are the "owner" of the object. 360 HeapRegion* r = _g1h->heap_region_containing(old); 361 362 if (!r->evacuation_failed()) { 363 r->set_evacuation_failed(true); 364 _g1h->hr_printer()->evac_failure(r); 365 } 366 367 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 368 369 _scanner.set_scanning_in_young(r->is_young()); 370 old->oop_iterate_backwards(&_scanner); 371 372 return old; 373 } else { 374 // Forward-to-self failed. Either someone else managed to allocate 375 // space for this object (old != forward_ptr) or they beat us in 376 // self-forwarding it (old == forward_ptr). 377 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), 378 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 379 "should not be in the CSet", 380 p2i(old), p2i(forward_ptr)); 381 return forward_ptr; 382 } 383 } 384 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) : 385 _g1h(g1h), 386 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)), 387 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)), 388 _young_cset_length(young_cset_length), 389 _n_workers(n_workers), 390 _flushed(false) { 391 for (uint i = 0; i < n_workers; ++i) { 392 _states[i] = NULL; 393 } 394 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t)); 395 } 396 397 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() { 398 assert(_flushed, "thread local state from the per thread states should have been flushed"); 399 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states); 400 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total); 401 }