1 /* 2 * Copyright (c) 2001, 2016, 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 "code/nmethod.hpp" 27 #include "gc/g1/g1BlockOffsetTable.inline.hpp" 28 #include "gc/g1/g1CollectedHeap.inline.hpp" 29 #include "gc/g1/g1HeapRegionTraceType.hpp" 30 #include "gc/g1/g1OopClosures.inline.hpp" 31 #include "gc/g1/heapRegion.inline.hpp" 32 #include "gc/g1/heapRegionBounds.inline.hpp" 33 #include "gc/g1/heapRegionManager.inline.hpp" 34 #include "gc/g1/heapRegionRemSet.hpp" 35 #include "gc/g1/heapRegionTracer.hpp" 36 #include "gc/shared/genOopClosures.inline.hpp" 37 #include "gc/shared/space.inline.hpp" 38 #include "logging/log.hpp" 39 #include "memory/iterator.hpp" 40 #include "memory/resourceArea.hpp" 41 #include "oops/oop.inline.hpp" 42 #include "runtime/atomic.hpp" 43 #include "runtime/orderAccess.inline.hpp" 44 45 int HeapRegion::LogOfHRGrainBytes = 0; 46 int HeapRegion::LogOfHRGrainWords = 0; 47 size_t HeapRegion::GrainBytes = 0; 48 size_t HeapRegion::GrainWords = 0; 49 size_t HeapRegion::CardsPerRegion = 0; 50 51 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1, 52 HeapRegion* hr, 53 G1ParPushHeapRSClosure* cl, 54 CardTableModRefBS::PrecisionStyle precision) : 55 DirtyCardToOopClosure(hr, cl, precision, NULL), 56 _hr(hr), _rs_scan(cl), _g1(g1) { } 57 58 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r, 59 OopClosure* oc) : 60 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { } 61 62 void HeapRegionDCTOC::walk_mem_region(MemRegion mr, 63 HeapWord* bottom, 64 HeapWord* top) { 65 G1CollectedHeap* g1h = _g1; 66 size_t oop_size; 67 HeapWord* cur = bottom; 68 69 // Start filtering what we add to the remembered set. If the object is 70 // not considered dead, either because it is marked (in the mark bitmap) 71 // or it was allocated after marking finished, then we add it. Otherwise 72 // we can safely ignore the object. 73 if (!g1h->is_obj_dead(oop(cur))) { 74 oop_size = oop(cur)->oop_iterate_size(_rs_scan, mr); 75 } else { 76 oop_size = _hr->block_size(cur); 77 } 78 79 cur += oop_size; 80 81 if (cur < top) { 82 oop cur_oop = oop(cur); 83 oop_size = _hr->block_size(cur); 84 HeapWord* next_obj = cur + oop_size; 85 while (next_obj < top) { 86 // Keep filtering the remembered set. 87 if (!g1h->is_obj_dead(cur_oop)) { 88 // Bottom lies entirely below top, so we can call the 89 // non-memRegion version of oop_iterate below. 90 cur_oop->oop_iterate(_rs_scan); 91 } 92 cur = next_obj; 93 cur_oop = oop(cur); 94 oop_size = _hr->block_size(cur); 95 next_obj = cur + oop_size; 96 } 97 98 // Last object. Need to do dead-obj filtering here too. 99 if (!g1h->is_obj_dead(oop(cur))) { 100 oop(cur)->oop_iterate(_rs_scan, mr); 101 } 102 } 103 } 104 105 size_t HeapRegion::max_region_size() { 106 return HeapRegionBounds::max_size(); 107 } 108 109 size_t HeapRegion::min_region_size_in_words() { 110 return HeapRegionBounds::min_size() >> LogHeapWordSize; 111 } 112 113 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) { 114 size_t region_size = G1HeapRegionSize; 115 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) { 116 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2; 117 region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(), 118 HeapRegionBounds::min_size()); 119 } 120 121 int region_size_log = log2_long((jlong) region_size); 122 // Recalculate the region size to make sure it's a power of 123 // 2. This means that region_size is the largest power of 2 that's 124 // <= what we've calculated so far. 125 region_size = ((size_t)1 << region_size_log); 126 127 // Now make sure that we don't go over or under our limits. 128 if (region_size < HeapRegionBounds::min_size()) { 129 region_size = HeapRegionBounds::min_size(); 130 } else if (region_size > HeapRegionBounds::max_size()) { 131 region_size = HeapRegionBounds::max_size(); 132 } 133 134 // And recalculate the log. 135 region_size_log = log2_long((jlong) region_size); 136 137 // Now, set up the globals. 138 guarantee(LogOfHRGrainBytes == 0, "we should only set it once"); 139 LogOfHRGrainBytes = region_size_log; 140 141 guarantee(LogOfHRGrainWords == 0, "we should only set it once"); 142 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize; 143 144 guarantee(GrainBytes == 0, "we should only set it once"); 145 // The cast to int is safe, given that we've bounded region_size by 146 // MIN_REGION_SIZE and MAX_REGION_SIZE. 147 GrainBytes = region_size; 148 log_info(gc, heap)("Heap region size: " SIZE_FORMAT "M", GrainBytes / M); 149 150 guarantee(GrainWords == 0, "we should only set it once"); 151 GrainWords = GrainBytes >> LogHeapWordSize; 152 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity"); 153 154 guarantee(CardsPerRegion == 0, "we should only set it once"); 155 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift; 156 157 if (G1HeapRegionSize != GrainBytes) { 158 FLAG_SET_ERGO(size_t, G1HeapRegionSize, GrainBytes); 159 } 160 } 161 162 void HeapRegion::reset_after_compaction() { 163 G1ContiguousSpace::reset_after_compaction(); 164 // After a compaction the mark bitmap is invalid, so we must 165 // treat all objects as being inside the unmarked area. 166 zero_marked_bytes(); 167 init_top_at_mark_start(); 168 } 169 170 void HeapRegion::hr_clear(bool keep_remset, bool clear_space, bool locked) { 171 assert(_humongous_start_region == NULL, 172 "we should have already filtered out humongous regions"); 173 assert(!in_collection_set(), 174 "Should not clear heap region %u in the collection set", hrm_index()); 175 176 set_allocation_context(AllocationContext::system()); 177 set_young_index_in_cset(-1); 178 uninstall_surv_rate_group(); 179 set_free(); 180 reset_pre_dummy_top(); 181 182 if (!keep_remset) { 183 if (locked) { 184 rem_set()->clear_locked(); 185 } else { 186 rem_set()->clear(); 187 } 188 } 189 190 zero_marked_bytes(); 191 192 init_top_at_mark_start(); 193 _gc_time_stamp = G1CollectedHeap::heap()->get_gc_time_stamp(); 194 if (clear_space) clear(SpaceDecorator::Mangle); 195 } 196 197 void HeapRegion::par_clear() { 198 assert(used() == 0, "the region should have been already cleared"); 199 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal"); 200 HeapRegionRemSet* hrrs = rem_set(); 201 hrrs->clear(); 202 CardTableModRefBS* ct_bs = 203 barrier_set_cast<CardTableModRefBS>(G1CollectedHeap::heap()->barrier_set()); 204 ct_bs->clear(MemRegion(bottom(), end())); 205 } 206 207 void HeapRegion::calc_gc_efficiency() { 208 // GC efficiency is the ratio of how much space would be 209 // reclaimed over how long we predict it would take to reclaim it. 210 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 211 G1Policy* g1p = g1h->g1_policy(); 212 213 // Retrieve a prediction of the elapsed time for this region for 214 // a mixed gc because the region will only be evacuated during a 215 // mixed gc. 216 double region_elapsed_time_ms = 217 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */); 218 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms; 219 } 220 221 void HeapRegion::set_free() { 222 report_region_type_change(G1HeapRegionTraceType::Free); 223 _type.set_free(); 224 } 225 226 void HeapRegion::set_eden() { 227 report_region_type_change(G1HeapRegionTraceType::Eden); 228 _type.set_eden(); 229 } 230 231 void HeapRegion::set_eden_pre_gc() { 232 report_region_type_change(G1HeapRegionTraceType::Eden); 233 _type.set_eden_pre_gc(); 234 } 235 236 void HeapRegion::set_survivor() { 237 report_region_type_change(G1HeapRegionTraceType::Survivor); 238 _type.set_survivor(); 239 } 240 241 void HeapRegion::set_old() { 242 report_region_type_change(G1HeapRegionTraceType::Old); 243 _type.set_old(); 244 } 245 246 void HeapRegion::set_archive() { 247 report_region_type_change(G1HeapRegionTraceType::Archive); 248 _type.set_archive(); 249 } 250 251 void HeapRegion::set_starts_humongous(HeapWord* obj_top, size_t fill_size) { 252 assert(!is_humongous(), "sanity / pre-condition"); 253 assert(top() == bottom(), "should be empty"); 254 255 report_region_type_change(G1HeapRegionTraceType::StartsHumongous); 256 _type.set_starts_humongous(); 257 _humongous_start_region = this; 258 259 _bot_part.set_for_starts_humongous(obj_top, fill_size); 260 } 261 262 void HeapRegion::set_continues_humongous(HeapRegion* first_hr) { 263 assert(!is_humongous(), "sanity / pre-condition"); 264 assert(top() == bottom(), "should be empty"); 265 assert(first_hr->is_starts_humongous(), "pre-condition"); 266 267 report_region_type_change(G1HeapRegionTraceType::ContinuesHumongous); 268 _type.set_continues_humongous(); 269 _humongous_start_region = first_hr; 270 } 271 272 void HeapRegion::clear_humongous() { 273 assert(is_humongous(), "pre-condition"); 274 275 assert(capacity() == HeapRegion::GrainBytes, "pre-condition"); 276 _humongous_start_region = NULL; 277 } 278 279 HeapRegion::HeapRegion(uint hrm_index, 280 G1BlockOffsetTable* bot, 281 MemRegion mr) : 282 G1ContiguousSpace(bot), 283 _hrm_index(hrm_index), 284 _allocation_context(AllocationContext::system()), 285 _humongous_start_region(NULL), 286 _evacuation_failed(false), 287 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0), 288 _next(NULL), _prev(NULL), 289 #ifdef ASSERT 290 _containing_set(NULL), 291 #endif // ASSERT 292 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1), 293 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0), 294 _predicted_bytes_to_copy(0) 295 { 296 _rem_set = new HeapRegionRemSet(bot, this); 297 298 initialize(mr); 299 } 300 301 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) { 302 assert(_rem_set->is_empty(), "Remembered set must be empty"); 303 304 G1ContiguousSpace::initialize(mr, clear_space, mangle_space); 305 306 hr_clear(false /*par*/, false /*clear_space*/); 307 set_top(bottom()); 308 record_timestamp(); 309 } 310 311 void HeapRegion::report_region_type_change(G1HeapRegionTraceType::Type to) { 312 HeapRegionTracer::send_region_type_change(_hrm_index, 313 get_trace_type(), 314 to, 315 (uintptr_t)bottom(), 316 used(), 317 (uint)allocation_context()); 318 } 319 320 CompactibleSpace* HeapRegion::next_compaction_space() const { 321 return G1CollectedHeap::heap()->next_compaction_region(this); 322 } 323 324 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark, 325 bool during_conc_mark) { 326 // We always recreate the prev marking info and we'll explicitly 327 // mark all objects we find to be self-forwarded on the prev 328 // bitmap. So all objects need to be below PTAMS. 329 _prev_marked_bytes = 0; 330 331 if (during_initial_mark) { 332 // During initial-mark, we'll also explicitly mark all objects 333 // we find to be self-forwarded on the next bitmap. So all 334 // objects need to be below NTAMS. 335 _next_top_at_mark_start = top(); 336 _next_marked_bytes = 0; 337 } else if (during_conc_mark) { 338 // During concurrent mark, all objects in the CSet (including 339 // the ones we find to be self-forwarded) are implicitly live. 340 // So all objects need to be above NTAMS. 341 _next_top_at_mark_start = bottom(); 342 _next_marked_bytes = 0; 343 } 344 } 345 346 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark, 347 bool during_conc_mark, 348 size_t marked_bytes) { 349 assert(marked_bytes <= used(), 350 "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used()); 351 _prev_top_at_mark_start = top(); 352 _prev_marked_bytes = marked_bytes; 353 } 354 355 // Humongous objects are allocated directly in the old-gen. Need 356 // special handling for concurrent processing encountering an 357 // in-progress allocation. 358 static bool do_oops_on_card_in_humongous(MemRegion mr, 359 FilterOutOfRegionClosure* cl, 360 HeapRegion* hr, 361 G1CollectedHeap* g1h) { 362 assert(hr->is_humongous(), "precondition"); 363 HeapRegion* sr = hr->humongous_start_region(); 364 oop obj = oop(sr->bottom()); 365 366 // If concurrent and klass_or_null is NULL, then space has been 367 // allocated but the object has not yet been published by setting 368 // the klass. That can only happen if the card is stale. However, 369 // we've already set the card clean, so we must return failure, 370 // since the allocating thread could have performed a write to the 371 // card that might be missed otherwise. 372 if (!g1h->is_gc_active() && (obj->klass_or_null_acquire() == NULL)) { 373 return false; 374 } 375 376 // Only filler objects follow a humongous object in the containing 377 // regions, and we can ignore those. So only process the one 378 // humongous object. 379 if (!g1h->is_obj_dead(obj, sr)) { 380 if (obj->is_objArray() || (sr->bottom() < mr.start())) { 381 // objArrays are always marked precisely, so limit processing 382 // with mr. Non-objArrays might be precisely marked, and since 383 // it's humongous it's worthwhile avoiding full processing. 384 // However, the card could be stale and only cover filler 385 // objects. That should be rare, so not worth checking for; 386 // instead let it fall out from the bounded iteration. 387 obj->oop_iterate(cl, mr); 388 } else { 389 // If obj is not an objArray and mr contains the start of the 390 // obj, then this could be an imprecise mark, and we need to 391 // process the entire object. 392 obj->oop_iterate(cl); 393 } 394 } 395 return true; 396 } 397 398 bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr, 399 FilterOutOfRegionClosure* cl, 400 jbyte* card_ptr) { 401 assert(card_ptr != NULL, "pre-condition"); 402 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 403 404 // If we're within a stop-world GC, then we might look at a card in a 405 // GC alloc region that extends onto a GC LAB, which may not be 406 // parseable. Stop such at the "scan_top" of the region. 407 if (g1h->is_gc_active()) { 408 mr = mr.intersection(MemRegion(bottom(), scan_top())); 409 } else { 410 mr = mr.intersection(used_region()); 411 } 412 if (mr.is_empty()) { 413 return true; 414 } 415 416 // The intersection of the incoming mr (for the card) and the 417 // allocated part of the region is non-empty. This implies that 418 // we have actually allocated into this region. The code in 419 // G1CollectedHeap.cpp that allocates a new region sets the 420 // is_young tag on the region before allocating. Thus we 421 // safely know if this region is young. 422 if (is_young()) { 423 return true; 424 } 425 426 // We can only clean the card here, after we make the decision that 427 // the card is not young. 428 *card_ptr = CardTableModRefBS::clean_card_val(); 429 // We must complete this write before we do any of the reads below. 430 OrderAccess::storeload(); 431 432 // Special handling for humongous regions. 433 if (is_humongous()) { 434 return do_oops_on_card_in_humongous(mr, cl, this, g1h); 435 } 436 437 // During GC we limit mr by scan_top. So we never get here with an 438 // mr covering objects allocated during GC. Non-humongous objects 439 // are only allocated in the old-gen during GC. So the parts of the 440 // heap that may be examined here are always parsable; there's no 441 // need to use klass_or_null here to detect in-progress allocations. 442 443 // Cache the boundaries of the memory region in some const locals 444 HeapWord* const start = mr.start(); 445 HeapWord* const end = mr.end(); 446 447 // Find the obj that extends onto mr.start(). 448 // Update BOT as needed while finding start of (possibly dead) 449 // object containing the start of the region. 450 HeapWord* cur = block_start(start); 451 452 #ifdef ASSERT 453 { 454 assert(cur <= start, 455 "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start)); 456 HeapWord* next = cur + block_size(cur); 457 assert(start < next, 458 "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next)); 459 } 460 #endif 461 462 do { 463 oop obj = oop(cur); 464 assert(obj->is_oop(true), "Not an oop at " PTR_FORMAT, p2i(cur)); 465 assert(obj->klass_or_null() != NULL, 466 "Unparsable heap at " PTR_FORMAT, p2i(cur)); 467 468 if (g1h->is_obj_dead(obj, this)) { 469 // Carefully step over dead object. 470 cur += block_size(cur); 471 } else { 472 // Step over live object, and process its references. 473 cur += obj->size(); 474 // Non-objArrays are usually marked imprecise at the object 475 // start, in which case we need to iterate over them in full. 476 // objArrays are precisely marked, but can still be iterated 477 // over in full if completely covered. 478 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) { 479 obj->oop_iterate(cl); 480 } else { 481 obj->oop_iterate(cl, mr); 482 } 483 } 484 } while (cur < end); 485 486 return true; 487 } 488 489 // Code roots support 490 491 void HeapRegion::add_strong_code_root(nmethod* nm) { 492 HeapRegionRemSet* hrrs = rem_set(); 493 hrrs->add_strong_code_root(nm); 494 } 495 496 void HeapRegion::add_strong_code_root_locked(nmethod* nm) { 497 assert_locked_or_safepoint(CodeCache_lock); 498 HeapRegionRemSet* hrrs = rem_set(); 499 hrrs->add_strong_code_root_locked(nm); 500 } 501 502 void HeapRegion::remove_strong_code_root(nmethod* nm) { 503 HeapRegionRemSet* hrrs = rem_set(); 504 hrrs->remove_strong_code_root(nm); 505 } 506 507 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const { 508 HeapRegionRemSet* hrrs = rem_set(); 509 hrrs->strong_code_roots_do(blk); 510 } 511 512 class VerifyStrongCodeRootOopClosure: public OopClosure { 513 const HeapRegion* _hr; 514 nmethod* _nm; 515 bool _failures; 516 bool _has_oops_in_region; 517 518 template <class T> void do_oop_work(T* p) { 519 T heap_oop = oopDesc::load_heap_oop(p); 520 if (!oopDesc::is_null(heap_oop)) { 521 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 522 523 // Note: not all the oops embedded in the nmethod are in the 524 // current region. We only look at those which are. 525 if (_hr->is_in(obj)) { 526 // Object is in the region. Check that its less than top 527 if (_hr->top() <= (HeapWord*)obj) { 528 // Object is above top 529 log_error(gc, verify)("Object " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ") is above top " PTR_FORMAT, 530 p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top())); 531 _failures = true; 532 return; 533 } 534 // Nmethod has at least one oop in the current region 535 _has_oops_in_region = true; 536 } 537 } 538 } 539 540 public: 541 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm): 542 _hr(hr), _failures(false), _has_oops_in_region(false) {} 543 544 void do_oop(narrowOop* p) { do_oop_work(p); } 545 void do_oop(oop* p) { do_oop_work(p); } 546 547 bool failures() { return _failures; } 548 bool has_oops_in_region() { return _has_oops_in_region; } 549 }; 550 551 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 552 const HeapRegion* _hr; 553 bool _failures; 554 public: 555 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) : 556 _hr(hr), _failures(false) {} 557 558 void do_code_blob(CodeBlob* cb) { 559 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 560 if (nm != NULL) { 561 // Verify that the nemthod is live 562 if (!nm->is_alive()) { 563 log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has dead nmethod " PTR_FORMAT " in its strong code roots", 564 p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm)); 565 _failures = true; 566 } else { 567 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm); 568 nm->oops_do(&oop_cl); 569 if (!oop_cl.has_oops_in_region()) { 570 log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has nmethod " PTR_FORMAT " in its strong code roots with no pointers into region", 571 p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm)); 572 _failures = true; 573 } else if (oop_cl.failures()) { 574 log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has other failures for nmethod " PTR_FORMAT, 575 p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm)); 576 _failures = true; 577 } 578 } 579 } 580 } 581 582 bool failures() { return _failures; } 583 }; 584 585 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const { 586 if (!G1VerifyHeapRegionCodeRoots) { 587 // We're not verifying code roots. 588 return; 589 } 590 if (vo == VerifyOption_G1UseMarkWord) { 591 // Marking verification during a full GC is performed after class 592 // unloading, code cache unloading, etc so the strong code roots 593 // attached to each heap region are in an inconsistent state. They won't 594 // be consistent until the strong code roots are rebuilt after the 595 // actual GC. Skip verifying the strong code roots in this particular 596 // time. 597 assert(VerifyDuringGC, "only way to get here"); 598 return; 599 } 600 601 HeapRegionRemSet* hrrs = rem_set(); 602 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length(); 603 604 // if this region is empty then there should be no entries 605 // on its strong code root list 606 if (is_empty()) { 607 if (strong_code_roots_length > 0) { 608 log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] is empty but has " SIZE_FORMAT " code root entries", 609 p2i(bottom()), p2i(end()), strong_code_roots_length); 610 *failures = true; 611 } 612 return; 613 } 614 615 if (is_continues_humongous()) { 616 if (strong_code_roots_length > 0) { 617 log_error(gc, verify)("region " HR_FORMAT " is a continuation of a humongous region but has " SIZE_FORMAT " code root entries", 618 HR_FORMAT_PARAMS(this), strong_code_roots_length); 619 *failures = true; 620 } 621 return; 622 } 623 624 VerifyStrongCodeRootCodeBlobClosure cb_cl(this); 625 strong_code_roots_do(&cb_cl); 626 627 if (cb_cl.failures()) { 628 *failures = true; 629 } 630 } 631 632 void HeapRegion::print() const { print_on(tty); } 633 void HeapRegion::print_on(outputStream* st) const { 634 st->print("|%4u", this->_hrm_index); 635 st->print("|" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT, 636 p2i(bottom()), p2i(top()), p2i(end())); 637 st->print("|%3d%%", (int) ((double) used() * 100 / capacity())); 638 st->print("|%2s", get_short_type_str()); 639 if (in_collection_set()) { 640 st->print("|CS"); 641 } else { 642 st->print("| "); 643 } 644 st->print("|TS%3u", _gc_time_stamp); 645 st->print("|AC%3u", allocation_context()); 646 st->print_cr("|TAMS " PTR_FORMAT ", " PTR_FORMAT "|", 647 p2i(prev_top_at_mark_start()), p2i(next_top_at_mark_start())); 648 } 649 650 class G1VerificationClosure : public OopClosure { 651 protected: 652 G1CollectedHeap* _g1h; 653 CardTableModRefBS* _bs; 654 oop _containing_obj; 655 bool _failures; 656 int _n_failures; 657 VerifyOption _vo; 658 public: 659 // _vo == UsePrevMarking -> use "prev" marking information, 660 // _vo == UseNextMarking -> use "next" marking information, 661 // _vo == UseMarkWord -> use mark word from object header. 662 G1VerificationClosure(G1CollectedHeap* g1h, VerifyOption vo) : 663 _g1h(g1h), _bs(barrier_set_cast<CardTableModRefBS>(g1h->barrier_set())), 664 _containing_obj(NULL), _failures(false), _n_failures(0), _vo(vo) { 665 } 666 667 void set_containing_obj(oop obj) { 668 _containing_obj = obj; 669 } 670 671 bool failures() { return _failures; } 672 int n_failures() { return _n_failures; } 673 674 void print_object(outputStream* out, oop obj) { 675 #ifdef PRODUCT 676 Klass* k = obj->klass(); 677 const char* class_name = k->external_name(); 678 out->print_cr("class name %s", class_name); 679 #else // PRODUCT 680 obj->print_on(out); 681 #endif // PRODUCT 682 } 683 }; 684 685 class VerifyLiveClosure : public G1VerificationClosure { 686 public: 687 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {} 688 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 689 virtual void do_oop(oop* p) { do_oop_work(p); } 690 691 template <class T> 692 void do_oop_work(T* p) { 693 assert(_containing_obj != NULL, "Precondition"); 694 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo), 695 "Precondition"); 696 verify_liveness(p); 697 } 698 699 template <class T> 700 void verify_liveness(T* p) { 701 T heap_oop = oopDesc::load_heap_oop(p); 702 Log(gc, verify) log; 703 if (!oopDesc::is_null(heap_oop)) { 704 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 705 bool failed = false; 706 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) { 707 MutexLockerEx x(ParGCRareEvent_lock, 708 Mutex::_no_safepoint_check_flag); 709 710 if (!_failures) { 711 log.error("----------"); 712 } 713 ResourceMark rm; 714 if (!_g1h->is_in_closed_subset(obj)) { 715 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 716 log.error("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")", 717 p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end())); 718 print_object(log.error_stream(), _containing_obj); 719 log.error("points to obj " PTR_FORMAT " not in the heap", p2i(obj)); 720 } else { 721 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 722 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj); 723 log.error("Field " PTR_FORMAT " of live obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")", 724 p2i(p), p2i(_containing_obj), p2i(from->bottom()), p2i(from->end())); 725 print_object(log.error_stream(), _containing_obj); 726 log.error("points to dead obj " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ")", 727 p2i(obj), p2i(to->bottom()), p2i(to->end())); 728 print_object(log.error_stream(), obj); 729 } 730 log.error("----------"); 731 _failures = true; 732 failed = true; 733 _n_failures++; 734 } 735 } 736 } 737 }; 738 739 class VerifyRemSetClosure : public G1VerificationClosure { 740 public: 741 VerifyRemSetClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {} 742 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 743 virtual void do_oop(oop* p) { do_oop_work(p); } 744 745 template <class T> 746 void do_oop_work(T* p) { 747 assert(_containing_obj != NULL, "Precondition"); 748 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo), 749 "Precondition"); 750 verify_remembered_set(p); 751 } 752 753 template <class T> 754 void verify_remembered_set(T* p) { 755 T heap_oop = oopDesc::load_heap_oop(p); 756 Log(gc, verify) log; 757 if (!oopDesc::is_null(heap_oop)) { 758 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 759 bool failed = false; 760 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 761 HeapRegion* to = _g1h->heap_region_containing(obj); 762 if (from != NULL && to != NULL && 763 from != to && 764 !to->is_pinned()) { 765 jbyte cv_obj = *_bs->byte_for_const(_containing_obj); 766 jbyte cv_field = *_bs->byte_for_const(p); 767 const jbyte dirty = CardTableModRefBS::dirty_card_val(); 768 769 bool is_bad = !(from->is_young() 770 || to->rem_set()->contains_reference(p) 771 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed 772 (_containing_obj->is_objArray() ? 773 cv_field == dirty 774 : cv_obj == dirty || cv_field == dirty)); 775 if (is_bad) { 776 MutexLockerEx x(ParGCRareEvent_lock, 777 Mutex::_no_safepoint_check_flag); 778 779 if (!_failures) { 780 log.error("----------"); 781 } 782 log.error("Missing rem set entry:"); 783 log.error("Field " PTR_FORMAT " of obj " PTR_FORMAT ", in region " HR_FORMAT, 784 p2i(p), p2i(_containing_obj), HR_FORMAT_PARAMS(from)); 785 ResourceMark rm; 786 _containing_obj->print_on(log.error_stream()); 787 log.error("points to obj " PTR_FORMAT " in region " HR_FORMAT, p2i(obj), HR_FORMAT_PARAMS(to)); 788 if (obj->is_oop()) { 789 obj->print_on(log.error_stream()); 790 } 791 log.error("Obj head CTE = %d, field CTE = %d.", cv_obj, cv_field); 792 log.error("----------"); 793 _failures = true; 794 if (!failed) _n_failures++; 795 } 796 } 797 } 798 } 799 }; 800 801 // This really ought to be commoned up into OffsetTableContigSpace somehow. 802 // We would need a mechanism to make that code skip dead objects. 803 804 void HeapRegion::verify(VerifyOption vo, 805 bool* failures) const { 806 G1CollectedHeap* g1 = G1CollectedHeap::heap(); 807 *failures = false; 808 HeapWord* p = bottom(); 809 HeapWord* prev_p = NULL; 810 VerifyLiveClosure vl_cl(g1, vo); 811 VerifyRemSetClosure vr_cl(g1, vo); 812 bool is_region_humongous = is_humongous(); 813 size_t object_num = 0; 814 while (p < top()) { 815 oop obj = oop(p); 816 size_t obj_size = block_size(p); 817 object_num += 1; 818 819 if (!g1->is_obj_dead_cond(obj, this, vo)) { 820 if (obj->is_oop()) { 821 Klass* klass = obj->klass(); 822 bool is_metaspace_object = Metaspace::contains(klass) || 823 (vo == VerifyOption_G1UsePrevMarking && 824 ClassLoaderDataGraph::unload_list_contains(klass)); 825 if (!is_metaspace_object) { 826 log_error(gc, verify)("klass " PTR_FORMAT " of object " PTR_FORMAT " " 827 "not metadata", p2i(klass), p2i(obj)); 828 *failures = true; 829 return; 830 } else if (!klass->is_klass()) { 831 log_error(gc, verify)("klass " PTR_FORMAT " of object " PTR_FORMAT " " 832 "not a klass", p2i(klass), p2i(obj)); 833 *failures = true; 834 return; 835 } else { 836 vl_cl.set_containing_obj(obj); 837 if (!g1->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC) { 838 // verify liveness and rem_set 839 vr_cl.set_containing_obj(obj); 840 G1Mux2Closure mux(&vl_cl, &vr_cl); 841 obj->oop_iterate_no_header(&mux); 842 843 if (vr_cl.failures()) { 844 *failures = true; 845 } 846 if (G1MaxVerifyFailures >= 0 && 847 vr_cl.n_failures() >= G1MaxVerifyFailures) { 848 return; 849 } 850 } else { 851 // verify only liveness 852 obj->oop_iterate_no_header(&vl_cl); 853 } 854 if (vl_cl.failures()) { 855 *failures = true; 856 } 857 if (G1MaxVerifyFailures >= 0 && 858 vl_cl.n_failures() >= G1MaxVerifyFailures) { 859 return; 860 } 861 } 862 } else { 863 log_error(gc, verify)(PTR_FORMAT " not an oop", p2i(obj)); 864 *failures = true; 865 return; 866 } 867 } 868 prev_p = p; 869 p += obj_size; 870 } 871 872 if (!is_young() && !is_empty()) { 873 _bot_part.verify(); 874 } 875 876 if (is_region_humongous) { 877 oop obj = oop(this->humongous_start_region()->bottom()); 878 if ((HeapWord*)obj > bottom() || (HeapWord*)obj + obj->size() < bottom()) { 879 log_error(gc, verify)("this humongous region is not part of its' humongous object " PTR_FORMAT, p2i(obj)); 880 *failures = true; 881 return; 882 } 883 } 884 885 if (!is_region_humongous && p != top()) { 886 log_error(gc, verify)("end of last object " PTR_FORMAT " " 887 "does not match top " PTR_FORMAT, p2i(p), p2i(top())); 888 *failures = true; 889 return; 890 } 891 892 HeapWord* the_end = end(); 893 // Do some extra BOT consistency checking for addresses in the 894 // range [top, end). BOT look-ups in this range should yield 895 // top. No point in doing that if top == end (there's nothing there). 896 if (p < the_end) { 897 // Look up top 898 HeapWord* addr_1 = p; 899 HeapWord* b_start_1 = _bot_part.block_start_const(addr_1); 900 if (b_start_1 != p) { 901 log_error(gc, verify)("BOT look up for top: " PTR_FORMAT " " 902 " yielded " PTR_FORMAT ", expecting " PTR_FORMAT, 903 p2i(addr_1), p2i(b_start_1), p2i(p)); 904 *failures = true; 905 return; 906 } 907 908 // Look up top + 1 909 HeapWord* addr_2 = p + 1; 910 if (addr_2 < the_end) { 911 HeapWord* b_start_2 = _bot_part.block_start_const(addr_2); 912 if (b_start_2 != p) { 913 log_error(gc, verify)("BOT look up for top + 1: " PTR_FORMAT " " 914 " yielded " PTR_FORMAT ", expecting " PTR_FORMAT, 915 p2i(addr_2), p2i(b_start_2), p2i(p)); 916 *failures = true; 917 return; 918 } 919 } 920 921 // Look up an address between top and end 922 size_t diff = pointer_delta(the_end, p) / 2; 923 HeapWord* addr_3 = p + diff; 924 if (addr_3 < the_end) { 925 HeapWord* b_start_3 = _bot_part.block_start_const(addr_3); 926 if (b_start_3 != p) { 927 log_error(gc, verify)("BOT look up for top + diff: " PTR_FORMAT " " 928 " yielded " PTR_FORMAT ", expecting " PTR_FORMAT, 929 p2i(addr_3), p2i(b_start_3), p2i(p)); 930 *failures = true; 931 return; 932 } 933 } 934 935 // Look up end - 1 936 HeapWord* addr_4 = the_end - 1; 937 HeapWord* b_start_4 = _bot_part.block_start_const(addr_4); 938 if (b_start_4 != p) { 939 log_error(gc, verify)("BOT look up for end - 1: " PTR_FORMAT " " 940 " yielded " PTR_FORMAT ", expecting " PTR_FORMAT, 941 p2i(addr_4), p2i(b_start_4), p2i(p)); 942 *failures = true; 943 return; 944 } 945 } 946 947 verify_strong_code_roots(vo, failures); 948 } 949 950 void HeapRegion::verify() const { 951 bool dummy = false; 952 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy); 953 } 954 955 void HeapRegion::verify_rem_set(VerifyOption vo, bool* failures) const { 956 G1CollectedHeap* g1 = G1CollectedHeap::heap(); 957 *failures = false; 958 HeapWord* p = bottom(); 959 HeapWord* prev_p = NULL; 960 VerifyRemSetClosure vr_cl(g1, vo); 961 while (p < top()) { 962 oop obj = oop(p); 963 size_t obj_size = block_size(p); 964 965 if (!g1->is_obj_dead_cond(obj, this, vo)) { 966 if (obj->is_oop()) { 967 vr_cl.set_containing_obj(obj); 968 obj->oop_iterate_no_header(&vr_cl); 969 970 if (vr_cl.failures()) { 971 *failures = true; 972 } 973 if (G1MaxVerifyFailures >= 0 && 974 vr_cl.n_failures() >= G1MaxVerifyFailures) { 975 return; 976 } 977 } else { 978 log_error(gc, verify)(PTR_FORMAT " not an oop", p2i(obj)); 979 *failures = true; 980 return; 981 } 982 } 983 984 prev_p = p; 985 p += obj_size; 986 } 987 } 988 989 void HeapRegion::verify_rem_set() const { 990 bool failures = false; 991 verify_rem_set(VerifyOption_G1UsePrevMarking, &failures); 992 guarantee(!failures, "HeapRegion RemSet verification failed"); 993 } 994 995 void HeapRegion::prepare_for_compaction(CompactPoint* cp) { 996 scan_and_forward(this, cp); 997 } 998 999 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go 1000 // away eventually. 1001 1002 void G1ContiguousSpace::clear(bool mangle_space) { 1003 set_top(bottom()); 1004 _scan_top = bottom(); 1005 CompactibleSpace::clear(mangle_space); 1006 reset_bot(); 1007 } 1008 1009 #ifndef PRODUCT 1010 void G1ContiguousSpace::mangle_unused_area() { 1011 mangle_unused_area_complete(); 1012 } 1013 1014 void G1ContiguousSpace::mangle_unused_area_complete() { 1015 SpaceMangler::mangle_region(MemRegion(top(), end())); 1016 } 1017 #endif 1018 1019 void G1ContiguousSpace::print() const { 1020 print_short(); 1021 tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 1022 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 1023 p2i(bottom()), p2i(top()), p2i(_bot_part.threshold()), p2i(end())); 1024 } 1025 1026 HeapWord* G1ContiguousSpace::initialize_threshold() { 1027 return _bot_part.initialize_threshold(); 1028 } 1029 1030 HeapWord* G1ContiguousSpace::cross_threshold(HeapWord* start, 1031 HeapWord* end) { 1032 _bot_part.alloc_block(start, end); 1033 return _bot_part.threshold(); 1034 } 1035 1036 HeapWord* G1ContiguousSpace::scan_top() const { 1037 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1038 HeapWord* local_top = top(); 1039 OrderAccess::loadload(); 1040 const unsigned local_time_stamp = _gc_time_stamp; 1041 assert(local_time_stamp <= g1h->get_gc_time_stamp(), "invariant"); 1042 if (local_time_stamp < g1h->get_gc_time_stamp()) { 1043 return local_top; 1044 } else { 1045 return _scan_top; 1046 } 1047 } 1048 1049 void G1ContiguousSpace::record_timestamp() { 1050 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1051 uint curr_gc_time_stamp = g1h->get_gc_time_stamp(); 1052 1053 if (_gc_time_stamp < curr_gc_time_stamp) { 1054 // Setting the time stamp here tells concurrent readers to look at 1055 // scan_top to know the maximum allowed address to look at. 1056 1057 // scan_top should be bottom for all regions except for the 1058 // retained old alloc region which should have scan_top == top 1059 HeapWord* st = _scan_top; 1060 guarantee(st == _bottom || st == _top, "invariant"); 1061 1062 _gc_time_stamp = curr_gc_time_stamp; 1063 } 1064 } 1065 1066 void G1ContiguousSpace::record_retained_region() { 1067 // scan_top is the maximum address where it's safe for the next gc to 1068 // scan this region. 1069 _scan_top = top(); 1070 } 1071 1072 void G1ContiguousSpace::safe_object_iterate(ObjectClosure* blk) { 1073 object_iterate(blk); 1074 } 1075 1076 void G1ContiguousSpace::object_iterate(ObjectClosure* blk) { 1077 HeapWord* p = bottom(); 1078 while (p < top()) { 1079 if (block_is_obj(p)) { 1080 blk->do_object(oop(p)); 1081 } 1082 p += block_size(p); 1083 } 1084 } 1085 1086 G1ContiguousSpace::G1ContiguousSpace(G1BlockOffsetTable* bot) : 1087 _bot_part(bot, this), 1088 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true), 1089 _gc_time_stamp(0) 1090 { 1091 } 1092 1093 void G1ContiguousSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) { 1094 CompactibleSpace::initialize(mr, clear_space, mangle_space); 1095 _top = bottom(); 1096 _scan_top = bottom(); 1097 set_saved_mark_word(NULL); 1098 reset_bot(); 1099 } 1100