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