1/*
2 * Copyright (c) 2002, 2017, 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.
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23 */
24
25#include "precompiled.hpp"
26#include "gc/parallel/gcTaskManager.hpp"
27#include "gc/parallel/mutableSpace.hpp"
28#include "gc/parallel/parallelScavengeHeap.hpp"
29#include "gc/parallel/psOldGen.hpp"
30#include "gc/parallel/psPromotionManager.inline.hpp"
31#include "gc/parallel/psScavenge.inline.hpp"
32#include "gc/shared/gcTrace.hpp"
33#include "gc/shared/preservedMarks.inline.hpp"
34#include "gc/shared/taskqueue.inline.hpp"
35#include "logging/log.hpp"
36#include "logging/logStream.hpp"
37#include "memory/allocation.inline.hpp"
38#include "memory/memRegion.hpp"
39#include "memory/padded.inline.hpp"
40#include "memory/resourceArea.hpp"
41#include "oops/instanceKlass.inline.hpp"
42#include "oops/instanceMirrorKlass.inline.hpp"
43#include "oops/objArrayKlass.inline.hpp"
44#include "oops/oop.inline.hpp"
45
46PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
47OopStarTaskQueueSet*           PSPromotionManager::_stack_array_depth = NULL;
48PreservedMarksSet*             PSPromotionManager::_preserved_marks_set = NULL;
49PSOldGen*                      PSPromotionManager::_old_gen = NULL;
50MutableSpace*                  PSPromotionManager::_young_space = NULL;
51
52void PSPromotionManager::initialize() {
53  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
54
55  _old_gen = heap->old_gen();
56  _young_space = heap->young_gen()->to_space();
57
58  const uint promotion_manager_num = ParallelGCThreads + 1;
59
60  // To prevent false sharing, we pad the PSPromotionManagers
61  // and make sure that the first instance starts at a cache line.
62  assert(_manager_array == NULL, "Attempt to initialize twice");
63  _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
64  guarantee(_manager_array != NULL, "Could not initialize promotion manager");
65
66  _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
67  guarantee(_stack_array_depth != NULL, "Could not initialize promotion manager");
68
69  // Create and register the PSPromotionManager(s) for the worker threads.
70  for(uint i=0; i<ParallelGCThreads; i++) {
71    stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
72  }
73  // The VMThread gets its own PSPromotionManager, which is not available
74  // for work stealing.
75
76  assert(_preserved_marks_set == NULL, "Attempt to initialize twice");
77  _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
78  guarantee(_preserved_marks_set != NULL, "Could not initialize preserved marks set");
79  _preserved_marks_set->init(promotion_manager_num);
80  for (uint i = 0; i < promotion_manager_num; i += 1) {
81    _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
82  }
83}
84
85// Helper functions to get around the circular dependency between
86// psScavenge.inline.hpp and psPromotionManager.inline.hpp.
87bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
88  return PSScavenge::should_scavenge(p, check_to_space);
89}
90bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
91  return PSScavenge::should_scavenge(p, check_to_space);
92}
93
94PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
95  assert(index < ParallelGCThreads, "index out of range");
96  assert(_manager_array != NULL, "Sanity");
97  return &_manager_array[index];
98}
99
100PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
101  assert(_manager_array != NULL, "Sanity");
102  return &_manager_array[ParallelGCThreads];
103}
104
105void PSPromotionManager::pre_scavenge() {
106  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
107
108  _preserved_marks_set->assert_empty();
109  _young_space = heap->young_gen()->to_space();
110
111  for(uint i=0; i<ParallelGCThreads+1; i++) {
112    manager_array(i)->reset();
113  }
114}
115
116bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
117  bool promotion_failure_occurred = false;
118
119  TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
120  for (uint i = 0; i < ParallelGCThreads + 1; i++) {
121    PSPromotionManager* manager = manager_array(i);
122    assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
123    if (manager->_promotion_failed_info.has_failed()) {
124      gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
125      promotion_failure_occurred = true;
126    }
127    manager->flush_labs();
128  }
129  if (!promotion_failure_occurred) {
130    // If there was no promotion failure, the preserved mark stacks
131    // should be empty.
132    _preserved_marks_set->assert_empty();
133  }
134  return promotion_failure_occurred;
135}
136
137#if TASKQUEUE_STATS
138void
139PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
140  #define FMT " " SIZE_FORMAT_W(10)
141  out->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,
142                _arrays_chunked, _array_chunks_processed);
143  #undef FMT
144}
145
146static const char* const pm_stats_hdr[] = {
147  "    --------masked-------     arrays      array",
148  "thr       push      steal    chunked     chunks",
149  "--- ---------- ---------- ---------- ----------"
150};
151
152void
153PSPromotionManager::print_taskqueue_stats() {
154  if (!log_develop_is_enabled(Trace, gc, task, stats)) {
155    return;
156  }
157  Log(gc, task, stats) log;
158  ResourceMark rm;
159  LogStream ls(log.trace());
160  outputStream* out = &ls;
161  out->print_cr("== GC Tasks Stats, GC %3d",
162                ParallelScavengeHeap::heap()->total_collections());
163
164  TaskQueueStats totals;
165  out->print("thr "); TaskQueueStats::print_header(1, out); out->cr();
166  out->print("--- "); TaskQueueStats::print_header(2, out); out->cr();
167  for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
168    TaskQueueStats& next = manager_array(i)->_claimed_stack_depth.stats;
169    out->print("%3d ", i); next.print(out); out->cr();
170    totals += next;
171  }
172  out->print("tot "); totals.print(out); out->cr();
173
174  const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
175  for (uint i = 0; i < hlines; ++i) out->print_cr("%s", pm_stats_hdr[i]);
176  for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
177    manager_array(i)->print_local_stats(out, i);
178  }
179}
180
181void
182PSPromotionManager::reset_stats() {
183  claimed_stack_depth()->stats.reset();
184  _masked_pushes = _masked_steals = 0;
185  _arrays_chunked = _array_chunks_processed = 0;
186}
187#endif // TASKQUEUE_STATS
188
189PSPromotionManager::PSPromotionManager() {
190  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
191
192  // We set the old lab's start array.
193  _old_lab.set_start_array(old_gen()->start_array());
194
195  uint queue_size;
196  claimed_stack_depth()->initialize();
197  queue_size = claimed_stack_depth()->max_elems();
198
199  _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
200  if (_totally_drain) {
201    _target_stack_size = 0;
202  } else {
203    // don't let the target stack size to be more than 1/4 of the entries
204    _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
205                                     (uint) (queue_size / 4));
206  }
207
208  _array_chunk_size = ParGCArrayScanChunk;
209  // let's choose 1.5x the chunk size
210  _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
211
212  _preserved_marks = NULL;
213
214  reset();
215}
216
217void PSPromotionManager::reset() {
218  assert(stacks_empty(), "reset of non-empty stack");
219
220  // We need to get an assert in here to make sure the labs are always flushed.
221
222  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
223
224  // Do not prefill the LAB's, save heap wastage!
225  HeapWord* lab_base = young_space()->top();
226  _young_lab.initialize(MemRegion(lab_base, (size_t)0));
227  _young_gen_is_full = false;
228
229  lab_base = old_gen()->object_space()->top();
230  _old_lab.initialize(MemRegion(lab_base, (size_t)0));
231  _old_gen_is_full = false;
232
233  _promotion_failed_info.reset();
234
235  TASKQUEUE_STATS_ONLY(reset_stats());
236}
237
238void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
239  assert(_preserved_marks == NULL, "do not set it twice");
240  _preserved_marks = preserved_marks;
241}
242
243class ParRestoreGCTask : public GCTask {
244private:
245  const uint _id;
246  PreservedMarksSet* const _preserved_marks_set;
247  volatile size_t* const _total_size_addr;
248
249public:
250  virtual char* name() {
251    return (char*) "preserved mark restoration task";
252  }
253
254  virtual void do_it(GCTaskManager* manager, uint which){
255    _preserved_marks_set->get(_id)->restore_and_increment(_total_size_addr);
256  }
257
258  ParRestoreGCTask(uint id,
259                   PreservedMarksSet* preserved_marks_set,
260                   volatile size_t* total_size_addr)
261    : _id(id),
262      _preserved_marks_set(preserved_marks_set),
263      _total_size_addr(total_size_addr) { }
264};
265
266class PSRestorePreservedMarksTaskExecutor : public RestorePreservedMarksTaskExecutor {
267private:
268  GCTaskManager* _gc_task_manager;
269
270public:
271  PSRestorePreservedMarksTaskExecutor(GCTaskManager* gc_task_manager)
272      : _gc_task_manager(gc_task_manager) { }
273
274  void restore(PreservedMarksSet* preserved_marks_set,
275               volatile size_t* total_size_addr) {
276    // GCTask / GCTaskQueue are ResourceObjs
277    ResourceMark rm;
278
279    GCTaskQueue* q = GCTaskQueue::create();
280    for (uint i = 0; i < preserved_marks_set->num(); i += 1) {
281      q->enqueue(new ParRestoreGCTask(i, preserved_marks_set, total_size_addr));
282    }
283    _gc_task_manager->execute_and_wait(q);
284  }
285};
286
287void PSPromotionManager::restore_preserved_marks() {
288  PSRestorePreservedMarksTaskExecutor task_executor(PSScavenge::gc_task_manager());
289  _preserved_marks_set->restore(&task_executor);
290}
291
292void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
293  totally_drain = totally_drain || _totally_drain;
294
295#ifdef ASSERT
296  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
297  MutableSpace* to_space = heap->young_gen()->to_space();
298  MutableSpace* old_space = heap->old_gen()->object_space();
299#endif /* ASSERT */
300
301  OopStarTaskQueue* const tq = claimed_stack_depth();
302  do {
303    StarTask p;
304
305    // Drain overflow stack first, so other threads can steal from
306    // claimed stack while we work.
307    while (tq->pop_overflow(p)) {
308      process_popped_location_depth(p);
309    }
310
311    if (totally_drain) {
312      while (tq->pop_local(p)) {
313        process_popped_location_depth(p);
314      }
315    } else {
316      while (tq->size() > _target_stack_size && tq->pop_local(p)) {
317        process_popped_location_depth(p);
318      }
319    }
320  } while ((totally_drain && !tq->taskqueue_empty()) || !tq->overflow_empty());
321
322  assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
323  assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
324  assert(tq->overflow_empty(), "Sanity");
325}
326
327void PSPromotionManager::flush_labs() {
328  assert(stacks_empty(), "Attempt to flush lab with live stack");
329
330  // If either promotion lab fills up, we can flush the
331  // lab but not refill it, so check first.
332  assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
333  if (!_young_lab.is_flushed())
334    _young_lab.flush();
335
336  assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
337  if (!_old_lab.is_flushed())
338    _old_lab.flush();
339
340  // Let PSScavenge know if we overflowed
341  if (_young_gen_is_full) {
342    PSScavenge::set_survivor_overflow(true);
343  }
344}
345
346template <class T> void PSPromotionManager::process_array_chunk_work(
347                                                 oop obj,
348                                                 int start, int end) {
349  assert(start <= end, "invariant");
350  T* const base      = (T*)objArrayOop(obj)->base();
351  T* p               = base + start;
352  T* const chunk_end = base + end;
353  while (p < chunk_end) {
354    if (PSScavenge::should_scavenge(p)) {
355      claim_or_forward_depth(p);
356    }
357    ++p;
358  }
359}
360
361void PSPromotionManager::process_array_chunk(oop old) {
362  assert(PSChunkLargeArrays, "invariant");
363  assert(old->is_objArray(), "invariant");
364  assert(old->is_forwarded(), "invariant");
365
366  TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
367
368  oop const obj = old->forwardee();
369
370  int start;
371  int const end = arrayOop(old)->length();
372  if (end > (int) _min_array_size_for_chunking) {
373    // we'll chunk more
374    start = end - _array_chunk_size;
375    assert(start > 0, "invariant");
376    arrayOop(old)->set_length(start);
377    push_depth(mask_chunked_array_oop(old));
378    TASKQUEUE_STATS_ONLY(++_masked_pushes);
379  } else {
380    // this is the final chunk for this array
381    start = 0;
382    int const actual_length = arrayOop(obj)->length();
383    arrayOop(old)->set_length(actual_length);
384  }
385
386  if (UseCompressedOops) {
387    process_array_chunk_work<narrowOop>(obj, start, end);
388  } else {
389    process_array_chunk_work<oop>(obj, start, end);
390  }
391}
392
393class PushContentsClosure : public ExtendedOopClosure {
394  PSPromotionManager* _pm;
395 public:
396  PushContentsClosure(PSPromotionManager* pm) : _pm(pm) {}
397
398  template <typename T> void do_oop_nv(T* p) {
399    if (PSScavenge::should_scavenge(p)) {
400      _pm->claim_or_forward_depth(p);
401    }
402  }
403
404  virtual void do_oop(oop* p)       { do_oop_nv(p); }
405  virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
406
407  // Don't use the oop verification code in the oop_oop_iterate framework.
408  debug_only(virtual bool should_verify_oops() { return false; })
409};
410
411void InstanceKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
412  PushContentsClosure cl(pm);
413  oop_oop_iterate_oop_maps_reverse<true>(obj, &cl);
414}
415
416void InstanceMirrorKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
417    // Note that we don't have to follow the mirror -> klass pointer, since all
418    // klasses that are dirty will be scavenged when we iterate over the
419    // ClassLoaderData objects.
420
421  InstanceKlass::oop_ps_push_contents(obj, pm);
422
423  PushContentsClosure cl(pm);
424  oop_oop_iterate_statics<true>(obj, &cl);
425}
426
427void InstanceClassLoaderKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
428  InstanceKlass::oop_ps_push_contents(obj, pm);
429
430  // This is called by the young collector. It will already have taken care of
431  // all class loader data. So, we don't have to follow the class loader ->
432  // class loader data link.
433}
434
435template <class T>
436static void oop_ps_push_contents_specialized(oop obj, InstanceRefKlass *klass, PSPromotionManager* pm) {
437  T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
438  if (PSScavenge::should_scavenge(referent_addr)) {
439    ReferenceProcessor* rp = PSScavenge::reference_processor();
440    if (rp->discover_reference(obj, klass->reference_type())) {
441      // reference already enqueued, referent and next will be traversed later
442      klass->InstanceKlass::oop_ps_push_contents(obj, pm);
443      return;
444    } else {
445      // treat referent as normal oop
446      pm->claim_or_forward_depth(referent_addr);
447    }
448  }
449  // Treat discovered as normal oop, if ref is not "active",
450  // i.e. if next is non-NULL.
451  T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
452  T  next_oop = oopDesc::load_heap_oop(next_addr);
453  if (!oopDesc::is_null(next_oop)) { // i.e. ref is not "active"
454    T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
455    log_develop_trace(gc, ref)("   Process discovered as normal " PTR_FORMAT, p2i(discovered_addr));
456    if (PSScavenge::should_scavenge(discovered_addr)) {
457      pm->claim_or_forward_depth(discovered_addr);
458    }
459  }
460  // Treat next as normal oop;  next is a link in the reference queue.
461  if (PSScavenge::should_scavenge(next_addr)) {
462    pm->claim_or_forward_depth(next_addr);
463  }
464  klass->InstanceKlass::oop_ps_push_contents(obj, pm);
465}
466
467void InstanceRefKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
468  if (UseCompressedOops) {
469    oop_ps_push_contents_specialized<narrowOop>(obj, this, pm);
470  } else {
471    oop_ps_push_contents_specialized<oop>(obj, this, pm);
472  }
473}
474
475void ObjArrayKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
476  assert(obj->is_objArray(), "obj must be obj array");
477  PushContentsClosure cl(pm);
478  oop_oop_iterate_elements<true>(objArrayOop(obj), &cl);
479}
480
481void TypeArrayKlass::oop_ps_push_contents(oop obj, PSPromotionManager* pm) {
482  assert(obj->is_typeArray(),"must be a type array");
483  ShouldNotReachHere();
484}
485
486oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {
487  assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
488
489  // Attempt to CAS in the header.
490  // This tests if the header is still the same as when
491  // this started.  If it is the same (i.e., no forwarding
492  // pointer has been installed), then this thread owns
493  // it.
494  if (obj->cas_forward_to(obj, obj_mark)) {
495    // We won any races, we "own" this object.
496    assert(obj == obj->forwardee(), "Sanity");
497
498    _promotion_failed_info.register_copy_failure(obj->size());
499
500    push_contents(obj);
501
502    _preserved_marks->push_if_necessary(obj, obj_mark);
503  }  else {
504    // We lost, someone else "owns" this object
505    guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
506
507    // No unallocation to worry about.
508    obj = obj->forwardee();
509  }
510
511  log_develop_trace(gc, scavenge)("{promotion-failure %s " PTR_FORMAT " (%d)}", obj->klass()->internal_name(), p2i(obj), obj->size());
512
513  return obj;
514}
515