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/continuationGCSupport.inline.hpp"
 33 #include "gc/shared/gcTrace.hpp"
 34 #include "gc/shared/preservedMarks.inline.hpp"
 35 #include "gc/shared/taskqueue.inline.hpp"
 36 #include "logging/log.hpp"
 37 #include "logging/logStream.hpp"
 38 #include "memory/allocation.inline.hpp"
 39 #include "memory/iterator.inline.hpp"
 40 #include "memory/memRegion.hpp"
 41 #include "memory/padded.inline.hpp"
 42 #include "memory/resourceArea.hpp"
 43 #include "oops/access.inline.hpp"
 44 #include "oops/compressedOops.inline.hpp"
 45 #include "oops/flatArrayKlass.inline.hpp"
 46 
 47 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
 48 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = NULL;
 49 PreservedMarksSet*             PSPromotionManager::_preserved_marks_set = NULL;
 50 PSOldGen*                      PSPromotionManager::_old_gen = NULL;
 51 MutableSpace*                  PSPromotionManager::_young_space = NULL;
 52 
 53 void PSPromotionManager::initialize() {
 54   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 55 
 56   _old_gen = heap->old_gen();
 57   _young_space = heap->young_gen()->to_space();
 58 
 59   const uint promotion_manager_num = ParallelGCThreads;
 60 
 61   // To prevent false sharing, we pad the PSPromotionManagers
 62   // and make sure that the first instance starts at a cache line.
 63   assert(_manager_array == NULL, "Attempt to initialize twice");
 64   _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
 65 
 66   _stack_array_depth = new PSScannerTasksQueueSet(ParallelGCThreads);
 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   _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[0];
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; 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; 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     manager->flush_string_dedup_requests();
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
137 void
138 PSPromotionManager::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,
141                 i, _array_chunk_pushes, _array_chunk_steals,
142                 _arrays_chunked, _array_chunks_processed);
143   #undef FMT
144 }
145 
146 static const char* const pm_stats_hdr[] = {
147   "    ----partial array----     arrays      array",
148   "thr       push      steal    chunked     chunks",
149   "--- ---------- ---------- ---------- ----------"
150 };
151 
152 void PSPromotionManager::print_taskqueue_stats() {
153   if (!log_is_enabled(Trace, gc, task, stats)) {
154     return;
155   }
156   Log(gc, task, stats) log;
157   ResourceMark rm;
158   LogStream ls(log.trace());
159 
160   stack_array_depth()->print_taskqueue_stats(&ls, "Oop Queue");
161 
162   const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
163   for (uint i = 0; i < hlines; ++i) ls.print_cr("%s", pm_stats_hdr[i]);
164   for (uint i = 0; i < ParallelGCThreads; ++i) {
165     manager_array(i)->print_local_stats(&ls, i);
166   }
167 }
168 
169 void PSPromotionManager::reset_stats() {
170   claimed_stack_depth()->stats.reset();
171   _array_chunk_pushes = _array_chunk_steals = 0;
172   _arrays_chunked = _array_chunks_processed = 0;
173 }
174 #endif // TASKQUEUE_STATS
175 
176 PSPromotionManager::PSPromotionManager() {
177   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
178 
179   // We set the old lab's start array.
180   _old_lab.set_start_array(old_gen()->start_array());
181 
182   uint queue_size;
183   queue_size = claimed_stack_depth()->max_elems();
184 
185   if (ParallelGCThreads == 1) {
186     _target_stack_size = 0;
187   } else {
188     // don't let the target stack size to be more than 1/4 of the entries
189     _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
190                                      (uint) (queue_size / 4));
191   }
192 
193   _array_chunk_size = ParGCArrayScanChunk;
194   // let's choose 1.5x the chunk size
195   _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
196 
197   _preserved_marks = NULL;
198 
199   reset();
200 }
201 
202 void PSPromotionManager::reset() {
203   assert(stacks_empty(), "reset of non-empty stack");
204 
205   // We need to get an assert in here to make sure the labs are always flushed.
206 
207   // Do not prefill the LAB's, save heap wastage!
208   HeapWord* lab_base = young_space()->top();
209   _young_lab.initialize(MemRegion(lab_base, (size_t)0));
210   _young_gen_is_full = false;
211 
212   lab_base = old_gen()->object_space()->top();
213   _old_lab.initialize(MemRegion(lab_base, (size_t)0));
214   _old_gen_is_full = false;
215 
216   _promotion_failed_info.reset();
217 
218   TASKQUEUE_STATS_ONLY(reset_stats());
219 }
220 
221 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
222   assert(_preserved_marks == NULL, "do not set it twice");
223   _preserved_marks = preserved_marks;
224 }
225 
226 void PSPromotionManager::restore_preserved_marks() {
227   _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
228 }
229 
230 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
231   totally_drain = totally_drain || (_target_stack_size == 0);
232 
233   PSScannerTasksQueue* const tq = claimed_stack_depth();
234   do {
235     ScannerTask task;
236 
237     // Drain overflow stack first, so other threads can steal from
238     // claimed stack while we work.
239     while (tq->pop_overflow(task)) {
240       process_popped_location_depth(task);
241     }
242 
243     if (totally_drain) {
244       while (tq->pop_local(task)) {
245         process_popped_location_depth(task);
246       }
247     } else {
248       while (tq->size() > _target_stack_size && tq->pop_local(task)) {
249         process_popped_location_depth(task);
250       }
251     }
252   } while ((totally_drain && !tq->taskqueue_empty()) || !tq->overflow_empty());
253 
254   assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
255   assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
256   assert(tq->overflow_empty(), "Sanity");
257 }
258 
259 void PSPromotionManager::flush_labs() {
260   assert(stacks_empty(), "Attempt to flush lab with live stack");
261 
262   // If either promotion lab fills up, we can flush the
263   // lab but not refill it, so check first.
264   assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
265   if (!_young_lab.is_flushed())
266     _young_lab.flush();
267 
268   assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
269   if (!_old_lab.is_flushed())
270     _old_lab.flush();
271 
272   // Let PSScavenge know if we overflowed
273   if (_young_gen_is_full) {
274     PSScavenge::set_survivor_overflow(true);
275   }
276 }
277 
278 template <class T> void PSPromotionManager::process_array_chunk_work(
279                                                  oop obj,
280                                                  int start, int end) {
281   assert(start <= end, "invariant");
282   T* const base      = (T*)objArrayOop(obj)->base();
283   T* p               = base + start;
284   T* const chunk_end = base + end;
285   while (p < chunk_end) {
286     if (PSScavenge::should_scavenge(p)) {
287       claim_or_forward_depth(p);
288     }
289     ++p;
290   }
291 }
292 
293 void PSPromotionManager::process_array_chunk(PartialArrayScanTask task) {
294   assert(PSChunkLargeArrays, "invariant");
295 
296   oop old = task.to_source_array();
297   assert(old->is_objArray(), "invariant");
298   assert(old->is_forwarded(), "invariant");
299 
300   TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
301 
302   oop const obj = old->forwardee();
303 
304   int start;
305   int const end = arrayOop(old)->length();
306   if (end > (int) _min_array_size_for_chunking) {
307     // we'll chunk more
308     start = end - _array_chunk_size;
309     assert(start > 0, "invariant");
310     arrayOop(old)->set_length(start);
311     push_depth(ScannerTask(PartialArrayScanTask(old)));
312     TASKQUEUE_STATS_ONLY(++_array_chunk_pushes);
313   } else {
314     // this is the final chunk for this array
315     start = 0;
316     int const actual_length = arrayOop(obj)->length();
317     arrayOop(old)->set_length(actual_length);
318   }
319 
320   if (UseCompressedOops) {
321     process_array_chunk_work<narrowOop>(obj, start, end);
322   } else {
323     process_array_chunk_work<oop>(obj, start, end);
324   }
325 }
326 
327 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
328   assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
329 
330   // Attempt to CAS in the header.
331   // This tests if the header is still the same as when
332   // this started.  If it is the same (i.e., no forwarding
333   // pointer has been installed), then this thread owns
334   // it.
335   if (obj->forward_to_atomic(obj, obj_mark) == NULL) {
336     // We won any races, we "own" this object.
337     assert(obj == obj->forwardee(), "Sanity");
338 
339     _promotion_failed_info.register_copy_failure(obj->size());
340 
341     ContinuationGCSupport::transform_stack_chunk(obj);
342 
343     push_contents(obj);
344 
345     // Save the markWord of promotion-failed objs in _preserved_marks for later
346     // restoration. This way we don't have to walk the young-gen to locate
347     // these promotion-failed objs.
348     _preserved_marks->push_always(obj, obj_mark);
349   }  else {
350     // We lost, someone else "owns" this object
351     guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
352 
353     // No unallocation to worry about.
354     obj = obj->forwardee();
355   }
356 
357   return obj;
358 }