1 /*
   2  * Copyright (c) 2002, 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 "gc/parallel/mutableSpace.hpp"
  27 #include "gc/parallel/parallelScavengeHeap.hpp"
  28 #include "gc/parallel/psOldGen.hpp"
  29 #include "gc/parallel/psPromotionManager.inline.hpp"
  30 #include "gc/parallel/psScavenge.inline.hpp"
  31 #include "gc/shared/gcTrace.hpp"
  32 #include "gc/shared/preservedMarks.inline.hpp"
  33 #include "gc/shared/taskqueue.inline.hpp"
  34 #include "logging/log.hpp"
  35 #include "memory/allocation.inline.hpp"
  36 #include "memory/memRegion.hpp"
  37 #include "memory/padded.inline.hpp"
  38 #include "memory/resourceArea.hpp"
  39 #include "oops/instanceKlass.inline.hpp"
  40 #include "oops/instanceMirrorKlass.inline.hpp"
  41 #include "oops/objArrayKlass.inline.hpp"
  42 #include "oops/oop.inline.hpp"
  43 
  44 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
  45 OopStarTaskQueueSet*           PSPromotionManager::_stack_array_depth = NULL;
  46 PreservedMarksSet*             PSPromotionManager::_preserved_marks_set = NULL;
  47 PSOldGen*                      PSPromotionManager::_old_gen = NULL;
  48 MutableSpace*                  PSPromotionManager::_young_space = NULL;
  49 
  50 void PSPromotionManager::initialize() {
  51   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
  52 
  53   _old_gen = heap->old_gen();
  54   _young_space = heap->young_gen()->to_space();
  55 
  56   const uint promotion_manager_num = ParallelGCThreads + 1;
  57 
  58   // To prevent false sharing, we pad the PSPromotionManagers
  59   // and make sure that the first instance starts at a cache line.
  60   assert(_manager_array == NULL, "Attempt to initialize twice");
  61   _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
  62   guarantee(_manager_array != NULL, "Could not initialize promotion manager");
  63 
  64   _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
  65   guarantee(_stack_array_depth != NULL, "Could not initialize promotion manager");
  66 
  67   // Create and register the PSPromotionManager(s) for the worker threads.
  68   for(uint i=0; i<ParallelGCThreads; i++) {
  69     stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
  70   }
  71   // The VMThread gets its own PSPromotionManager, which is not available
  72   // for work stealing.
  73 
  74   assert(_preserved_marks_set == NULL, "Attempt to initialize twice");
  75   _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
  76   guarantee(_preserved_marks_set != NULL, "Could not initialize preserved marks set");
  77   _preserved_marks_set->init(promotion_manager_num);
  78   for (uint i = 0; i < promotion_manager_num; i += 1) {
  79     _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
  80   }
  81 }
  82 
  83 // Helper functions to get around the circular dependency between
  84 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
  85 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
  86   return PSScavenge::should_scavenge(p, check_to_space);
  87 }
  88 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
  89   return PSScavenge::should_scavenge(p, check_to_space);
  90 }
  91 
  92 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
  93   assert(index < ParallelGCThreads, "index out of range");
  94   assert(_manager_array != NULL, "Sanity");
  95   return &_manager_array[index];
  96 }
  97 
  98 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
  99   assert(_manager_array != NULL, "Sanity");
 100   return &_manager_array[ParallelGCThreads];
 101 }
 102 
 103 void PSPromotionManager::pre_scavenge() {
 104   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 105 
 106   _preserved_marks_set->assert_empty();
 107   _young_space = heap->young_gen()->to_space();
 108 
 109   for(uint i=0; i<ParallelGCThreads+1; i++) {
 110     manager_array(i)->reset();
 111   }
 112 }
 113 
 114 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
 115   bool promotion_failure_occurred = false;
 116 
 117   TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
 118   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
 119     PSPromotionManager* manager = manager_array(i);
 120     assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
 121     if (manager->_promotion_failed_info.has_failed()) {
 122       gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
 123       promotion_failure_occurred = true;
 124     }
 125     manager->flush_labs();
 126   }
 127   if (!promotion_failure_occurred) {
 128     // If there was no promotion failure, the preserved mark stacks
 129     // should be empty.
 130     _preserved_marks_set->assert_empty();
 131   }
 132   return promotion_failure_occurred;
 133 }
 134 
 135 #if TASKQUEUE_STATS
 136 void
 137 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
 138   #define FMT " " SIZE_FORMAT_W(10)
 139   out->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,
 140                 _arrays_chunked, _array_chunks_processed);
 141   #undef FMT
 142 }
 143 
 144 static const char* const pm_stats_hdr[] = {
 145   "    --------masked-------     arrays      array",
 146   "thr       push      steal    chunked     chunks",
 147   "--- ---------- ---------- ---------- ----------"
 148 };
 149 
 150 void
 151 PSPromotionManager::print_taskqueue_stats() {
 152   if (!log_develop_is_enabled(Trace, gc, task, stats)) {
 153     return;
 154   }
 155   Log(gc, task, stats) log;
 156   ResourceMark rm;
 157   outputStream* out = log.trace_stream();
 158   out->print_cr("== GC Tasks Stats, GC %3d",
 159                 ParallelScavengeHeap::heap()->total_collections());
 160 
 161   TaskQueueStats totals;
 162   out->print("thr "); TaskQueueStats::print_header(1, out); out->cr();
 163   out->print("--- "); TaskQueueStats::print_header(2, out); out->cr();
 164   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
 165     TaskQueueStats& next = manager_array(i)->_claimed_stack_depth.stats;
 166     out->print("%3d ", i); next.print(out); out->cr();
 167     totals += next;
 168   }
 169   out->print("tot "); totals.print(out); out->cr();
 170 
 171   const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
 172   for (uint i = 0; i < hlines; ++i) out->print_cr("%s", pm_stats_hdr[i]);
 173   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
 174     manager_array(i)->print_local_stats(out, i);
 175   }
 176 }
 177 
 178 void
 179 PSPromotionManager::reset_stats() {
 180   claimed_stack_depth()->stats.reset();
 181   _masked_pushes = _masked_steals = 0;
 182   _arrays_chunked = _array_chunks_processed = 0;
 183 }
 184 #endif // TASKQUEUE_STATS
 185 
 186 PSPromotionManager::PSPromotionManager() {
 187   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 188 
 189   // We set the old lab's start array.
 190   _old_lab.set_start_array(old_gen()->start_array());
 191 
 192   uint queue_size;
 193   claimed_stack_depth()->initialize();
 194   queue_size = claimed_stack_depth()->max_elems();
 195 
 196   _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
 197   if (_totally_drain) {
 198     _target_stack_size = 0;
 199   } else {
 200     // don't let the target stack size to be more than 1/4 of the entries
 201     _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
 202                                      (uint) (queue_size / 4));
 203   }
 204 
 205   _array_chunk_size = ParGCArrayScanChunk;
 206   // let's choose 1.5x the chunk size
 207   _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
 208 
 209   _preserved_marks = NULL;
 210 
 211   reset();
 212 }
 213 
 214 void PSPromotionManager::reset() {
 215   assert(stacks_empty(), "reset of non-empty stack");
 216 
 217   // We need to get an assert in here to make sure the labs are always flushed.
 218 
 219   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 220 
 221   // Do not prefill the LAB's, save heap wastage!
 222   HeapWord* lab_base = young_space()->top();
 223   _young_lab.initialize(MemRegion(lab_base, (size_t)0));
 224   _young_gen_is_full = false;
 225 
 226   lab_base = old_gen()->object_space()->top();
 227   _old_lab.initialize(MemRegion(lab_base, (size_t)0));
 228   _old_gen_is_full = false;
 229 
 230   _promotion_failed_info.reset();
 231 
 232   TASKQUEUE_STATS_ONLY(reset_stats());
 233 }
 234 
 235 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
 236   assert(_preserved_marks == NULL, "do not set it twice");
 237   _preserved_marks = preserved_marks;
 238 }
 239 
 240 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
 241   totally_drain = totally_drain || _totally_drain;
 242 
 243 #ifdef ASSERT
 244   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 245   MutableSpace* to_space = heap->young_gen()->to_space();
 246   MutableSpace* old_space = heap->old_gen()->object_space();
 247 #endif /* ASSERT */
 248 
 249   OopStarTaskQueue* const tq = claimed_stack_depth();
 250   do {
 251     StarTask p;
 252 
 253     // Drain overflow stack first, so other threads can steal from
 254     // claimed stack while we work.
 255     while (tq->pop_overflow(p)) {
 256       process_popped_location_depth(p);
 257     }
 258 
 259     if (totally_drain) {
 260       while (tq->pop_local(p)) {
 261         process_popped_location_depth(p);
 262       }
 263     } else {
 264       while (tq->size() > _target_stack_size && tq->pop_local(p)) {
 265         process_popped_location_depth(p);
 266       }
 267     }
 268   } while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty());
 269 
 270   assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
 271   assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
 272   assert(tq->overflow_empty(), "Sanity");
 273 }
 274 
 275 void PSPromotionManager::flush_labs() {
 276   assert(stacks_empty(), "Attempt to flush lab with live stack");
 277 
 278   // If either promotion lab fills up, we can flush the
 279   // lab but not refill it, so check first.
 280   assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
 281   if (!_young_lab.is_flushed())
 282     _young_lab.flush();
 283 
 284   assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
 285   if (!_old_lab.is_flushed())
 286     _old_lab.flush();
 287 
 288   // Let PSScavenge know if we overflowed
 289   if (_young_gen_is_full) {
 290     PSScavenge::set_survivor_overflow(true);
 291   }
 292 }
 293 
 294 template <class T> void PSPromotionManager::process_array_chunk_work(
 295                                                  oop obj,
 296                                                  int start, int end) {
 297   assert(start <= end, "invariant");
 298   T* const base      = (T*)objArrayOop(obj)->base();
 299   T* p               = base + start;
 300   T* const chunk_end = base + end;
 301   while (p < chunk_end) {
 302     if (PSScavenge::should_scavenge(p)) {
 303       claim_or_forward_depth(p);
 304     }
 305     ++p;
 306   }
 307 }
 308 
 309 void PSPromotionManager::process_array_chunk(oop old) {
 310   assert(PSChunkLargeArrays, "invariant");
 311   assert(old->is_objArray(), "invariant");
 312   assert(old->is_forwarded(), "invariant");
 313 
 314   TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
 315 
 316   oop const obj = old->forwardee();
 317 
 318   int start;
 319   int const end = arrayOop(old)->length();
 320   if (end > (int) _min_array_size_for_chunking) {
 321     // we'll chunk more
 322     start = end - _array_chunk_size;
 323     assert(start > 0, "invariant");
 324     arrayOop(old)->set_length(start);
 325     push_depth(mask_chunked_array_oop(old));
 326     TASKQUEUE_STATS_ONLY(++_masked_pushes);
 327   } else {
 328     // this is the final chunk for this array
 329     start = 0;
 330     int const actual_length = arrayOop(obj)->length();
 331     arrayOop(old)->set_length(actual_length);
 332   }
 333 
 334   if (UseCompressedOops) {
 335     process_array_chunk_work<narrowOop>(obj, start, end);
 336   } else {
 337     process_array_chunk_work<oop>(obj, start, end);
 338   }
 339 }
 340 
 341 class PushContentsClosure : public ExtendedOopClosure {
 342   PSPromotionManager* _pm;
 343  public:
 344   PushContentsClosure(PSPromotionManager* pm) : _pm(pm) {}
 345 
 346   template <typename T> void do_oop_nv(T* p) {
 347     if (PSScavenge::should_scavenge(p)) {
 348       _pm->claim_or_forward_depth(p);
 349     }
 350   }
 351 
 352   virtual void do_oop(oop* p)       { do_oop_nv(p); }
 353   virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
 354 
 355   // Don't use the oop verification code in the oop_oop_iterate framework.
 356   debug_only(virtual bool should_verify_oops() { return false; })
 357 };
 358 
 359 void InstanceKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
 360   PushContentsClosure cl(pm);
 361   oop_oop_iterate_oop_maps_reverse<true>(obj, &cl);
 362 }
 363 
 364 void InstanceMirrorKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
 365     // Note that we don't have to follow the mirror -> klass pointer, since all
 366     // klasses that are dirty will be scavenged when we iterate over the
 367     // ClassLoaderData objects.
 368 
 369   InstanceKlass::oop_ps_push_contents(obj, pm);
 370 
 371   PushContentsClosure cl(pm);
 372   oop_oop_iterate_statics<true>(obj, &cl);
 373 }
 374 
 375 void InstanceClassLoaderKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
 376   InstanceKlass::oop_ps_push_contents(obj, pm);
 377 
 378   // This is called by the young collector. It will already have taken care of
 379   // all class loader data. So, we don't have to follow the class loader ->
 380   // class loader data link.
 381 }
 382 
 383 template <class T>
 384 static void oop_ps_push_contents_specialized(oop obj, InstanceRefKlass *klass, PSPromotionManager* pm) {
 385   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
 386   if (PSScavenge::should_scavenge(referent_addr)) {
 387     ReferenceProcessor* rp = PSScavenge::reference_processor();
 388     if (rp->discover_reference(obj, klass->reference_type())) {
 389       // reference already enqueued, referent and next will be traversed later
 390       klass->InstanceKlass::oop_ps_push_contents(obj, pm);
 391       return;
 392     } else {
 393       // treat referent as normal oop
 394       pm->claim_or_forward_depth(referent_addr);
 395     }
 396   }
 397   // Treat discovered as normal oop, if ref is not "active",
 398   // i.e. if next is non-NULL.
 399   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
 400   T  next_oop = oopDesc::load_heap_oop(next_addr);
 401   if (!oopDesc::is_null(next_oop)) { // i.e. ref is not "active"
 402     T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
 403     log_develop_trace(gc, ref)("   Process discovered as normal " PTR_FORMAT, p2i(discovered_addr));
 404     if (PSScavenge::should_scavenge(discovered_addr)) {
 405       pm->claim_or_forward_depth(discovered_addr);
 406     }
 407   }
 408   // Treat next as normal oop;  next is a link in the reference queue.
 409   if (PSScavenge::should_scavenge(next_addr)) {
 410     pm->claim_or_forward_depth(next_addr);
 411   }
 412   klass->InstanceKlass::oop_ps_push_contents(obj, pm);
 413 }
 414 
 415 void InstanceRefKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
 416   if (UseCompressedOops) {
 417     oop_ps_push_contents_specialized<narrowOop>(obj, this, pm);
 418   } else {
 419     oop_ps_push_contents_specialized<oop>(obj, this, pm);
 420   }
 421 }
 422 
 423 void ObjArrayKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
 424   assert(obj->is_objArray(), "obj must be obj array");
 425   PushContentsClosure cl(pm);
 426   oop_oop_iterate_elements<true>(objArrayOop(obj), &cl);
 427 }
 428 
 429 void TypeArrayKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
 430   assert(obj->is_typeArray(),"must be a type array");
 431   ShouldNotReachHere();
 432 }
 433 
 434 oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {
 435   assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
 436 
 437   // Attempt to CAS in the header.
 438   // This tests if the header is still the same as when
 439   // this started.  If it is the same (i.e., no forwarding
 440   // pointer has been installed), then this thread owns
 441   // it.
 442   if (obj->cas_forward_to(obj, obj_mark, memory_order_relaxed)) {
 443     // We won any races, we "own" this object.
 444     assert(obj == obj->forwardee(), "Sanity");
 445 
 446     _promotion_failed_info.register_copy_failure(obj->size());
 447 
 448     push_contents(obj);
 449 
 450     _preserved_marks->push_if_necessary(obj, obj_mark);
 451   }  else {
 452     // We lost, someone else "owns" this object
 453     guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
 454 
 455     // No unallocation to worry about.
 456     obj = obj->forwardee();
 457   }
 458 
 459   log_develop_trace(gc, scavenge)("{promotion-failure %s " PTR_FORMAT " (%d)}", obj->klass()->internal_name(), p2i(obj), obj->size());
 460 
 461   return obj;
 462 }