1 /*
  2  * Copyright (c) 2002, 2022, 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 "classfile/javaClasses.inline.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/iterator.inline.hpp"
 39 #include "memory/memRegion.hpp"
 40 #include "memory/padded.inline.hpp"
 41 #include "memory/resourceArea.hpp"
 42 #include "oops/access.inline.hpp"
 43 #include "oops/compressedOops.inline.hpp"
 44 
 45 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
 46 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = NULL;
 47 PreservedMarksSet*             PSPromotionManager::_preserved_marks_set = NULL;
 48 PSOldGen*                      PSPromotionManager::_old_gen = NULL;
 49 MutableSpace*                  PSPromotionManager::_young_space = NULL;
 50 
 51 void 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;
 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 
 64   _stack_array_depth = new PSScannerTasksQueueSet(ParallelGCThreads);
 65 
 66   // Create and register the PSPromotionManager(s) for the worker threads.
 67   for(uint i=0; i<ParallelGCThreads; i++) {
 68     stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
 69   }
 70   // The VMThread gets its own PSPromotionManager, which is not available
 71   // for work stealing.
 72 
 73   assert(_preserved_marks_set == NULL, "Attempt to initialize twice");
 74   _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
 75   _preserved_marks_set->init(promotion_manager_num);
 76   for (uint i = 0; i < promotion_manager_num; i += 1) {
 77     _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
 78   }
 79 }
 80 
 81 // Helper functions to get around the circular dependency between
 82 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
 83 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
 84   return PSScavenge::should_scavenge(p, check_to_space);
 85 }
 86 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
 87   return PSScavenge::should_scavenge(p, check_to_space);
 88 }
 89 
 90 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
 91   assert(index < ParallelGCThreads, "index out of range");
 92   assert(_manager_array != NULL, "Sanity");
 93   return &_manager_array[index];
 94 }
 95 
 96 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
 97   assert(_manager_array != NULL, "Sanity");
 98   return &_manager_array[0];
 99 }
100 
101 void PSPromotionManager::pre_scavenge() {
102   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
103 
104   _preserved_marks_set->assert_empty();
105   _young_space = heap->young_gen()->to_space();
106 
107   for(uint i=0; i<ParallelGCThreads; i++) {
108     manager_array(i)->reset();
109   }
110 }
111 
112 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
113   bool promotion_failure_occurred = false;
114 
115   TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
116   for (uint i = 0; i < ParallelGCThreads; i++) {
117     PSPromotionManager* manager = manager_array(i);
118     assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
119     if (manager->_promotion_failed_info.has_failed()) {
120       gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
121       promotion_failure_occurred = true;
122     }
123     manager->flush_labs();
124     manager->flush_string_dedup_requests();
125   }
126   if (!promotion_failure_occurred) {
127     // If there was no promotion failure, the preserved mark stacks
128     // should be empty.
129     _preserved_marks_set->assert_empty();
130   }
131   return promotion_failure_occurred;
132 }
133 
134 #if TASKQUEUE_STATS
135 void
136 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
137   #define FMT " " SIZE_FORMAT_W(10)
138   out->print_cr("%3u" FMT FMT FMT FMT,
139                 i, _array_chunk_pushes, _array_chunk_steals,
140                 _arrays_chunked, _array_chunks_processed);
141   #undef FMT
142 }
143 
144 static const char* const pm_stats_hdr[] = {
145   "    ----partial array----     arrays      array",
146   "thr       push      steal    chunked     chunks",
147   "--- ---------- ---------- ---------- ----------"
148 };
149 
150 void PSPromotionManager::print_taskqueue_stats() {
151   if (!log_is_enabled(Trace, gc, task, stats)) {
152     return;
153   }
154   Log(gc, task, stats) log;
155   ResourceMark rm;
156   LogStream ls(log.trace());
157 
158   stack_array_depth()->print_taskqueue_stats(&ls, "Oop Queue");
159 
160   const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
161   for (uint i = 0; i < hlines; ++i) ls.print_cr("%s", pm_stats_hdr[i]);
162   for (uint i = 0; i < ParallelGCThreads; ++i) {
163     manager_array(i)->print_local_stats(&ls, i);
164   }
165 }
166 
167 void PSPromotionManager::reset_stats() {
168   claimed_stack_depth()->stats.reset();
169   _array_chunk_pushes = _array_chunk_steals = 0;
170   _arrays_chunked = _array_chunks_processed = 0;
171 }
172 #endif // TASKQUEUE_STATS
173 
174 PSPromotionManager::PSPromotionManager() {
175   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
176 
177   // We set the old lab's start array.
178   _old_lab.set_start_array(old_gen()->start_array());
179 
180   uint queue_size;
181   queue_size = claimed_stack_depth()->max_elems();
182 
183   if (ParallelGCThreads == 1) {
184     _target_stack_size = 0;
185   } else {
186     // don't let the target stack size to be more than 1/4 of the entries
187     _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
188                                      (uint) (queue_size / 4));
189   }
190 
191   _array_chunk_size = ParGCArrayScanChunk;
192   // let's choose 1.5x the chunk size
193   _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
194 
195   _preserved_marks = NULL;
196 
197   reset();
198 }
199 
200 void PSPromotionManager::reset() {
201   assert(stacks_empty(), "reset of non-empty stack");
202 
203   // We need to get an assert in here to make sure the labs are always flushed.
204 
205   // Do not prefill the LAB's, save heap wastage!
206   HeapWord* lab_base = young_space()->top();
207   _young_lab.initialize(MemRegion(lab_base, (size_t)0));
208   _young_gen_is_full = false;
209 
210   lab_base = old_gen()->object_space()->top();
211   _old_lab.initialize(MemRegion(lab_base, (size_t)0));
212   _old_gen_is_full = false;
213 
214   _promotion_failed_info.reset();
215 
216   TASKQUEUE_STATS_ONLY(reset_stats());
217 }
218 
219 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
220   assert(_preserved_marks == NULL, "do not set it twice");
221   _preserved_marks = preserved_marks;
222 }
223 
224 void PSPromotionManager::restore_preserved_marks() {
225   _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
226 }
227 
228 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
229   totally_drain = totally_drain || (_target_stack_size == 0);
230 
231   PSScannerTasksQueue* const tq = claimed_stack_depth();
232   do {
233     ScannerTask task;
234 
235     // Drain overflow stack first, so other threads can steal from
236     // claimed stack while we work.
237     while (tq->pop_overflow(task)) {
238       process_popped_location_depth(task);
239     }
240 
241     if (totally_drain) {
242       while (tq->pop_local(task)) {
243         process_popped_location_depth(task);
244       }
245     } else {
246       while (tq->size() > _target_stack_size && tq->pop_local(task)) {
247         process_popped_location_depth(task);
248       }
249     }
250   } while ((totally_drain && !tq->taskqueue_empty()) || !tq->overflow_empty());
251 
252   assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
253   assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
254   assert(tq->overflow_empty(), "Sanity");
255 }
256 
257 void PSPromotionManager::flush_labs() {
258   assert(stacks_empty(), "Attempt to flush lab with live stack");
259 
260   // If either promotion lab fills up, we can flush the
261   // lab but not refill it, so check first.
262   assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
263   if (!_young_lab.is_flushed())
264     _young_lab.flush();
265 
266   assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
267   if (!_old_lab.is_flushed())
268     _old_lab.flush();
269 
270   // Let PSScavenge know if we overflowed
271   if (_young_gen_is_full) {
272     PSScavenge::set_survivor_overflow(true);
273   }
274 }
275 
276 template <class T> void PSPromotionManager::process_array_chunk_work(
277                                                  oop obj,
278                                                  int start, int end) {
279   assert(start <= end, "invariant");
280   T* const base      = (T*)objArrayOop(obj)->base();
281   T* p               = base + start;
282   T* const chunk_end = base + end;
283   while (p < chunk_end) {
284     if (PSScavenge::should_scavenge(p)) {
285       claim_or_forward_depth(p);
286     }
287     ++p;
288   }
289 }
290 
291 void PSPromotionManager::process_array_chunk(PartialArrayScanTask task) {
292   assert(PSChunkLargeArrays, "invariant");
293 
294   oop old = task.to_source_array();
295   assert(old->is_objArray(), "invariant");
296   assert(old->is_forwarded(), "invariant");
297 
298   TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
299 
300   oop const obj = old->forwardee();
301 
302   int start;
303   int const end = arrayOop(old)->length();
304   if (end > (int) _min_array_size_for_chunking) {
305     // we'll chunk more
306     start = end - _array_chunk_size;
307     assert(start > 0, "invariant");
308     arrayOop(old)->set_length(start);
309     push_depth(ScannerTask(PartialArrayScanTask(old)));
310     TASKQUEUE_STATS_ONLY(++_array_chunk_pushes);
311   } else {
312     // this is the final chunk for this array
313     start = 0;
314     int const actual_length = arrayOop(obj)->length();
315     arrayOop(old)->set_length(actual_length);
316   }
317 
318   if (UseCompressedOops) {
319     process_array_chunk_work<narrowOop>(obj, start, end);
320   } else {
321     process_array_chunk_work<oop>(obj, start, end);
322   }
323 }
324 
325 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
326   assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
327 
328   // Attempt to CAS in the header.
329   // This tests if the header is still the same as when
330   // this started.  If it is the same (i.e., no forwarding
331   // pointer has been installed), then this thread owns
332   // it.
333   if (obj->forward_to_atomic(obj, obj_mark) == NULL) {
334     // We won any races, we "own" this object.
335     assert(obj == obj->forwardee(), "Sanity");
336 
337     _promotion_failed_info.register_copy_failure(obj->size());
338 
339     push_contents(obj);
340 
341     // Save the markWord of promotion-failed objs in _preserved_marks for later
342     // restoration. This way we don't have to walk the young-gen to locate
343     // these promotion-failed objs.
344     _preserved_marks->push_always(obj, obj_mark);
345   }  else {
346     // We lost, someone else "owns" this object
347     guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
348 
349     // No unallocation to worry about.
350     obj = obj->forwardee();
351   }
352 
353   return obj;
354 }