1 /*
   2  * Copyright (c) 2014, 2019, 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,
  41                                            uint worker_id,
  42                                            size_t young_cset_length,
  43                                            size_t optional_cset_length)
  44   : _g1h(g1h),
  45     _refs(g1h->task_queue(worker_id)),
  46     _dcq(&g1h->dirty_card_queue_set()),
  47     _ct(g1h->card_table()),
  48     _closures(NULL),
  49     _plab_allocator(NULL),
  50     _age_table(false),
  51     _tenuring_threshold(g1h->policy()->tenuring_threshold()),
  52     _scanner(g1h, this),
  53     _worker_id(worker_id),
  54     _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1),
  55     _stack_trim_lower_threshold(GCDrainStackTargetSize),
  56     _trim_ticks(),
  57     _old_gen_is_full(false),
  58     _num_optional_regions(optional_cset_length)
  59 {
  60   // we allocate G1YoungSurvRateNumRegions plus one entries, since
  61   // we "sacrifice" entry 0 to keep track of surviving bytes for
  62   // non-young regions (where the age is -1)
  63   // We also add a few elements at the beginning and at the end in
  64   // an attempt to eliminate cache contention
  65   size_t real_length = 1 + young_cset_length;
  66   size_t array_length = PADDING_ELEM_NUM +
  67                       real_length +
  68                       PADDING_ELEM_NUM;
  69   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
  70   if (_surviving_young_words_base == NULL)
  71     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
  72                           "Not enough space for young surv histo.");
  73   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
  74   memset(_surviving_young_words, 0, real_length * sizeof(size_t));
  75 
  76   _plab_allocator = new G1PLABAllocator(_g1h->allocator());
  77 
  78   _dest[G1HeapRegionAttr::NotInCSet] = G1HeapRegionAttr::NotInCSet;
  79   // The dest for Young is used when the objects are aged enough to
  80   // need to be moved to the next space.
  81   _dest[G1HeapRegionAttr::Young] = G1HeapRegionAttr::Old;
  82   _dest[G1HeapRegionAttr::Old]   = G1HeapRegionAttr::Old;
  83 
  84   _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
  85 
  86   _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions];
  87 }
  88 
  89 // Pass locally gathered statistics to global state.
  90 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
  91   _dcq.flush();
  92   // Update allocation statistics.
  93   _plab_allocator->flush_and_retire_stats();
  94   _g1h->policy()->record_age_table(&_age_table);
  95 
  96   uint length = _g1h->collection_set()->young_region_length();
  97   for (uint region_index = 0; region_index < length; region_index++) {
  98     surviving_young_words[region_index] += _surviving_young_words[region_index];
  99   }
 100 }
 101 
 102 G1ParScanThreadState::~G1ParScanThreadState() {
 103   delete _plab_allocator;
 104   delete _closures;
 105   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
 106   delete[] _oops_into_optional_regions;
 107 }
 108 
 109 size_t G1ParScanThreadState::lab_waste_words() const {
 110   return _plab_allocator->waste();
 111 }
 112 
 113 size_t G1ParScanThreadState::lab_undo_waste_words() const {
 114   return _plab_allocator->undo_waste();
 115 }
 116 
 117 #ifdef ASSERT
 118 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
 119   assert(ref != NULL, "invariant");
 120   assert(UseCompressedOops, "sanity");
 121   assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
 122   oop p = RawAccess<>::oop_load(ref);
 123   assert(_g1h->is_in_g1_reserved(p),
 124          "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
 125   return true;
 126 }
 127 
 128 bool G1ParScanThreadState::verify_ref(oop* ref) const {
 129   assert(ref != NULL, "invariant");
 130   if (has_partial_array_mask(ref)) {
 131     // Must be in the collection set--it's already been copied.
 132     oop p = clear_partial_array_mask(ref);
 133     assert(_g1h->is_in_cset(p),
 134            "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
 135   } else {
 136     oop p = RawAccess<>::oop_load(ref);
 137     assert(_g1h->is_in_g1_reserved(p),
 138            "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
 139   }
 140   return true;
 141 }
 142 
 143 bool G1ParScanThreadState::verify_task(StarTask ref) const {
 144   if (ref.is_narrow()) {
 145     return verify_ref((narrowOop*) ref);
 146   } else {
 147     return verify_ref((oop*) ref);
 148   }
 149 }
 150 #endif // ASSERT
 151 
 152 void G1ParScanThreadState::trim_queue() {
 153   StarTask ref;
 154   do {
 155     // Fully drain the queue.
 156     trim_queue_to_threshold(0);
 157   } while (!_refs->is_empty());
 158 }
 159 
 160 HeapWord* G1ParScanThreadState::allocate_in_next_plab(G1HeapRegionAttr const region_attr,
 161                                                       G1HeapRegionAttr* dest,
 162                                                       size_t word_sz,
 163                                                       bool previous_plab_refill_failed) {
 164   assert(region_attr.is_in_cset_or_humongous(), "Unexpected region attr type: %s", region_attr.get_type_str());
 165   assert(dest->is_in_cset_or_humongous(), "Unexpected dest: %s region attr", dest->get_type_str());
 166 
 167   // Right now we only have two types of regions (young / old) so
 168   // let's keep the logic here simple. We can generalize it when necessary.
 169   if (dest->is_young()) {
 170     bool plab_refill_in_old_failed = false;
 171     HeapWord* const obj_ptr = _plab_allocator->allocate(G1HeapRegionAttr::Old,
 172                                                         word_sz,
 173                                                         &plab_refill_in_old_failed);
 174     // Make sure that we won't attempt to copy any other objects out
 175     // of a survivor region (given that apparently we cannot allocate
 176     // any new ones) to avoid coming into this slow path again and again.
 177     // Only consider failed PLAB refill here: failed inline allocations are
 178     // typically large, so not indicative of remaining space.
 179     if (previous_plab_refill_failed) {
 180       _tenuring_threshold = 0;
 181     }
 182 
 183     if (obj_ptr != NULL) {
 184       dest->set_old();
 185     } else {
 186       // We just failed to allocate in old gen. The same idea as explained above
 187       // for making survivor gen unavailable for allocation applies for old gen.
 188       _old_gen_is_full = plab_refill_in_old_failed;
 189     }
 190     return obj_ptr;
 191   } else {
 192     _old_gen_is_full = previous_plab_refill_failed;
 193     assert(dest->is_old(), "Unexpected dest region attr: %s", dest->get_type_str());
 194     // no other space to try.
 195     return NULL;
 196   }
 197 }
 198 
 199 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markOop const m, uint& age) {
 200   if (region_attr.is_young()) {
 201     age = !m->has_displaced_mark_helper() ? m->age()
 202                                           : m->displaced_mark_helper()->age();
 203     if (age < _tenuring_threshold) {
 204       return region_attr;
 205     }
 206   }
 207   return dest(region_attr);
 208 }
 209 
 210 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,
 211                                                   oop const old, size_t word_sz, uint age,
 212                                                   HeapWord * const obj_ptr) const {
 213   PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr);
 214   if (alloc_buf->contains(obj_ptr)) {
 215     _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
 216                                                              dest_attr.type() == G1HeapRegionAttr::Old,
 217                                                              alloc_buf->word_sz() * HeapWordSize);
 218   } else {
 219     _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
 220                                                               dest_attr.type() == G1HeapRegionAttr::Old);
 221   }
 222 }
 223 
 224 oop G1ParScanThreadState::copy_to_survivor_space(G1HeapRegionAttr const region_attr,
 225                                                  oop const old,
 226                                                  markOop const old_mark) {
 227   const size_t word_sz = old->size();
 228   HeapRegion* const from_region = _g1h->heap_region_containing(old);
 229   // +1 to make the -1 indexes valid...
 230   const int young_index = from_region->young_index_in_cset()+1;
 231   assert( (from_region->is_young() && young_index >  0) ||
 232          (!from_region->is_young() && young_index == 0), "invariant" );
 233 
 234   uint age = 0;
 235   G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);
 236   // The second clause is to prevent premature evacuation failure in case there
 237   // is still space in survivor, but old gen is full.
 238   if (_old_gen_is_full && dest_attr.is_old()) {
 239     return handle_evacuation_failure_par(old, old_mark);
 240   }
 241   HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz);
 242 
 243   // PLAB allocations should succeed most of the time, so we'll
 244   // normally check against NULL once and that's it.
 245   if (obj_ptr == NULL) {
 246     bool plab_refill_failed = false;
 247     obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_attr, word_sz, &plab_refill_failed);
 248     if (obj_ptr == NULL) {
 249       obj_ptr = allocate_in_next_plab(region_attr, &dest_attr, word_sz, plab_refill_failed);
 250       if (obj_ptr == NULL) {
 251         // This will either forward-to-self, or detect that someone else has
 252         // installed a forwarding pointer.
 253         return handle_evacuation_failure_par(old, old_mark);
 254       }
 255     }
 256     if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
 257       // The events are checked individually as part of the actual commit
 258       report_promotion_event(dest_attr, old, word_sz, age, obj_ptr);
 259     }
 260   }
 261 
 262   assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
 263   assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
 264 
 265 #ifndef PRODUCT
 266   // Should this evacuation fail?
 267   if (_g1h->evacuation_should_fail()) {
 268     // Doing this after all the allocation attempts also tests the
 269     // undo_allocation() method too.
 270     _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz);
 271     return handle_evacuation_failure_par(old, old_mark);
 272   }
 273 #endif // !PRODUCT
 274 
 275   // We're going to allocate linearly, so might as well prefetch ahead.
 276   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
 277 
 278   const oop obj = oop(obj_ptr);
 279   const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed);
 280   if (forward_ptr == NULL) {
 281     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
 282 
 283     if (dest_attr.is_young()) {
 284       if (age < markOopDesc::max_age) {
 285         age++;
 286       }
 287       if (old_mark->has_displaced_mark_helper()) {
 288         // In this case, we have to install the mark word first,
 289         // otherwise obj looks to be forwarded (the old mark word,
 290         // which contains the forward pointer, was copied)
 291         obj->set_mark_raw(old_mark);
 292         markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
 293         old_mark->set_displaced_mark_helper(new_mark);
 294       } else {
 295         obj->set_mark_raw(old_mark->set_age(age));
 296       }
 297       _age_table.add(age, word_sz);
 298     } else {
 299       obj->set_mark_raw(old_mark);
 300     }
 301 
 302     if (G1StringDedup::is_enabled()) {
 303       const bool is_from_young = region_attr.is_young();
 304       const bool is_to_young = dest_attr.is_young();
 305       assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
 306              "sanity");
 307       assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
 308              "sanity");
 309       G1StringDedup::enqueue_from_evacuation(is_from_young,
 310                                              is_to_young,
 311                                              _worker_id,
 312                                              obj);
 313     }
 314 
 315     _surviving_young_words[young_index] += word_sz;
 316 
 317     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
 318       // We keep track of the next start index in the length field of
 319       // the to-space object. The actual length can be found in the
 320       // length field of the from-space object.
 321       arrayOop(obj)->set_length(0);
 322       oop* old_p = set_partial_array_mask(old);
 323       do_oop_partial_array(old_p);
 324     } else {
 325       G1ScanInYoungSetter x(&_scanner, dest_attr.is_young());
 326       obj->oop_iterate_backwards(&_scanner);
 327     }
 328     return obj;
 329   } else {
 330     _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz);
 331     return forward_ptr;
 332   }
 333 }
 334 
 335 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
 336   assert(worker_id < _n_workers, "out of bounds access");
 337   if (_states[worker_id] == NULL) {
 338     _states[worker_id] =
 339       new G1ParScanThreadState(_g1h, worker_id, _young_cset_length, _optional_cset_length);
 340   }
 341   return _states[worker_id];
 342 }
 343 
 344 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
 345   assert(_flushed, "thread local state from the per thread states should have been flushed");
 346   return _surviving_young_words_total;
 347 }
 348 
 349 void G1ParScanThreadStateSet::flush() {
 350   assert(!_flushed, "thread local state from the per thread states should be flushed once");
 351 
 352   for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
 353     G1ParScanThreadState* pss = _states[worker_index];
 354 
 355     if (pss == NULL) {
 356       continue;
 357     }
 358 
 359     pss->flush(_surviving_young_words_total);
 360     delete pss;
 361     _states[worker_index] = NULL;
 362   }
 363   _flushed = true;
 364 }
 365 
 366 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
 367   for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
 368     G1ParScanThreadState* pss = _states[worker_index];
 369 
 370     if (pss == NULL) {
 371       continue;
 372     }
 373 
 374     size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
 375     _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_index, used_memory, G1GCPhaseTimes::ScanRSUsedMemory);
 376   }
 377 }
 378 
 379 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
 380   assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
 381 
 382   oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
 383   if (forward_ptr == NULL) {
 384     // Forward-to-self succeeded. We are the "owner" of the object.
 385     HeapRegion* r = _g1h->heap_region_containing(old);
 386 
 387     if (!r->evacuation_failed()) {
 388       r->set_evacuation_failed(true);
 389      _g1h->hr_printer()->evac_failure(r);
 390     }
 391 
 392     _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
 393 
 394     G1ScanInYoungSetter x(&_scanner, r->is_young());
 395     old->oop_iterate_backwards(&_scanner);
 396 
 397     return old;
 398   } else {
 399     // Forward-to-self failed. Either someone else managed to allocate
 400     // space for this object (old != forward_ptr) or they beat us in
 401     // self-forwarding it (old == forward_ptr).
 402     assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
 403            "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
 404            "should not be in the CSet",
 405            p2i(old), p2i(forward_ptr));
 406     return forward_ptr;
 407   }
 408 }
 409 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h,
 410                                                  uint n_workers,
 411                                                  size_t young_cset_length,
 412                                                  size_t optional_cset_length) :
 413     _g1h(g1h),
 414     _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
 415     _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
 416     _young_cset_length(young_cset_length),
 417     _optional_cset_length(optional_cset_length),
 418     _n_workers(n_workers),
 419     _flushed(false) {
 420   for (uint i = 0; i < n_workers; ++i) {
 421     _states[i] = NULL;
 422   }
 423   memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
 424 }
 425 
 426 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
 427   assert(_flushed, "thread local state from the per thread states should have been flushed");
 428   FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
 429   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
 430 }