1 /*
2 * Copyright (c) 2002, 2025, 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 "classfile/javaClasses.inline.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/continuationGCSupport.inline.hpp"
32 #include "gc/shared/gcTrace.hpp"
33 #include "gc/shared/partialArraySplitter.inline.hpp"
34 #include "gc/shared/partialArrayState.hpp"
35 #include "gc/shared/preservedMarks.inline.hpp"
36 #include "gc/shared/taskqueue.inline.hpp"
37 #include "logging/log.hpp"
38 #include "logging/logStream.hpp"
39 #include "memory/allocation.inline.hpp"
40 #include "memory/iterator.inline.hpp"
41 #include "memory/memRegion.hpp"
42 #include "memory/padded.inline.hpp"
43 #include "memory/resourceArea.hpp"
44 #include "oops/access.inline.hpp"
45 #include "oops/compressedOops.inline.hpp"
46 #include "utilities/checkedCast.hpp"
47
48 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = nullptr;
49 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = nullptr;
50 PreservedMarksSet* PSPromotionManager::_preserved_marks_set = nullptr;
51 PSOldGen* PSPromotionManager::_old_gen = nullptr;
52 MutableSpace* PSPromotionManager::_young_space = nullptr;
53 PartialArrayStateManager* PSPromotionManager::_partial_array_state_manager = nullptr;
54
55 void PSPromotionManager::initialize() {
56 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
57
58 _old_gen = heap->old_gen();
59 _young_space = heap->young_gen()->to_space();
60
61 const uint promotion_manager_num = ParallelGCThreads;
62
63 assert(_partial_array_state_manager == nullptr, "Attempt to initialize twice");
64 _partial_array_state_manager
65 = new PartialArrayStateManager(promotion_manager_num);
66
67 // To prevent false sharing, we pad the PSPromotionManagers
68 // and make sure that the first instance starts at a cache line.
69 assert(_manager_array == nullptr, "Attempt to initialize twice");
70 _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
71
72 _stack_array_depth = new PSScannerTasksQueueSet(promotion_manager_num);
73
74 // Create and register the PSPromotionManager(s) for the worker threads.
75 for(uint i=0; i<ParallelGCThreads; i++) {
76 stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
77 }
78 // The VMThread gets its own PSPromotionManager, which is not available
79 // for work stealing.
80
81 assert(_preserved_marks_set == nullptr, "Attempt to initialize twice");
82 _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
83 _preserved_marks_set->init(promotion_manager_num);
84 for (uint i = 0; i < promotion_manager_num; i += 1) {
85 _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
86 }
87 }
88
89 // Helper functions to get around the circular dependency between
90 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
91 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
92 return PSScavenge::should_scavenge(p, check_to_space);
93 }
94 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
95 return PSScavenge::should_scavenge(p, check_to_space);
96 }
97
98 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
99 assert(index < ParallelGCThreads, "index out of range");
100 assert(_manager_array != nullptr, "Sanity");
101 return &_manager_array[index];
102 }
103
104 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
105 assert(_manager_array != nullptr, "Sanity");
106 return &_manager_array[0];
107 }
108
109 void PSPromotionManager::pre_scavenge() {
110 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
111
112 _preserved_marks_set->assert_empty();
113 _young_space = heap->young_gen()->to_space();
114
115 for(uint i=0; i<ParallelGCThreads; i++) {
116 manager_array(i)->reset();
117 }
118 }
119
120 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
121 bool promotion_failure_occurred = false;
122
123 TASKQUEUE_STATS_ONLY(print_and_reset_taskqueue_stats());
124 for (uint i = 0; i < ParallelGCThreads; i++) {
125 PSPromotionManager* manager = manager_array(i);
126 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
127 if (manager->_promotion_failed_info.has_failed()) {
128 gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
129 promotion_failure_occurred = true;
130 }
131 manager->flush_labs();
132 manager->flush_string_dedup_requests();
133 }
134 // All PartialArrayStates have been returned to the allocator, since the
135 // claimed_stack_depths are all empty. Leave them there for use by future
136 // collections.
137
138 if (!promotion_failure_occurred) {
139 // If there was no promotion failure, the preserved mark stacks
140 // should be empty.
141 _preserved_marks_set->assert_empty();
142 }
143 return promotion_failure_occurred;
144 }
145
146 #if TASKQUEUE_STATS
147
148 void PSPromotionManager::print_and_reset_taskqueue_stats() {
149 stack_array_depth()->print_and_reset_taskqueue_stats("Oop Queue");
150
151 auto get_pa_stats = [&](uint i) {
152 return manager_array(i)->partial_array_task_stats();
153 };
154 PartialArrayTaskStats::log_set(ParallelGCThreads, get_pa_stats,
155 "Partial Array Task Stats");
156 for (uint i = 0; i < ParallelGCThreads; ++i) {
157 get_pa_stats(i)->reset();
158 }
159 }
160
161 PartialArrayTaskStats* PSPromotionManager::partial_array_task_stats() {
162 return _partial_array_splitter.stats();
163 }
164
165 #endif // TASKQUEUE_STATS
166
167 // Most members are initialized either by initialize() or reset().
168 PSPromotionManager::PSPromotionManager()
169 : _partial_array_splitter(_partial_array_state_manager, ParallelGCThreads)
170 {
171 // We set the old lab's start array.
172 _old_lab.set_start_array(old_gen()->start_array());
173
174 if (ParallelGCThreads == 1) {
175 _target_stack_size = 0;
176 } else {
177 _target_stack_size = GCDrainStackTargetSize;
178 }
179
180 // let's choose 1.5x the chunk size
181 _min_array_size_for_chunking = (3 * ParGCArrayScanChunk / 2);
182
183 _preserved_marks = nullptr;
184
185 reset();
186 }
187
188 void PSPromotionManager::reset() {
189 assert(stacks_empty(), "reset of non-empty stack");
190
191 // We need to get an assert in here to make sure the labs are always flushed.
192
193 // Do not prefill the LAB's, save heap wastage!
194 HeapWord* lab_base = young_space()->top();
195 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
196 _young_gen_is_full = false;
197
198 lab_base = old_gen()->object_space()->top();
199 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
200 _old_gen_is_full = false;
201
202 _promotion_failed_info.reset();
203 }
204
205 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
206 assert(_preserved_marks == nullptr, "do not set it twice");
207 _preserved_marks = preserved_marks;
208 }
209
210 void PSPromotionManager::restore_preserved_marks() {
211 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
212 }
213
214 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
215 const uint threshold = totally_drain ? 0
216 : _target_stack_size;
217
218 PSScannerTasksQueue* const tq = claimed_stack_depth();
219 do {
220 ScannerTask task;
221
222 // Drain overflow stack first, so other threads can steal from
223 // claimed stack while we work.
224 while (tq->pop_overflow(task)) {
225 if (!tq->try_push_to_taskqueue(task)) {
226 process_popped_location_depth(task, false);
227 }
228 }
229
230 while (tq->pop_local(task, threshold)) {
231 process_popped_location_depth(task, false);
232 }
233 } while (!tq->overflow_empty());
234
235 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
236 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
237 assert(tq->overflow_empty(), "Sanity");
238 }
239
240 void PSPromotionManager::flush_labs() {
241 assert(stacks_empty(), "Attempt to flush lab with live stack");
242
243 // If either promotion lab fills up, we can flush the
244 // lab but not refill it, so check first.
245 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
246 if (!_young_lab.is_flushed())
247 _young_lab.flush();
248
249 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
250 if (!_old_lab.is_flushed())
251 _old_lab.flush();
252
253 // Let PSScavenge know if we overflowed
254 if (_young_gen_is_full) {
255 PSScavenge::set_survivor_overflow(true);
256 }
257 }
258
259 template <class T>
260 void PSPromotionManager::process_array_chunk_work(oop obj, int start, int end) {
261 assert(start <= end, "invariant");
262 T* const base = (T*)objArrayOop(obj)->base();
263 T* p = base + start;
264 T* const chunk_end = base + end;
265 while (p < chunk_end) {
266 claim_or_forward_depth(p);
267 ++p;
268 }
269 }
270
271 void PSPromotionManager::process_array_chunk(PartialArrayState* state, bool stolen) {
272 // Access before release by claim().
273 oop new_obj = state->destination();
274 PartialArraySplitter::Claim claim =
275 _partial_array_splitter.claim(state, &_claimed_stack_depth, stolen);
276 int start = checked_cast<int>(claim._start);
277 int end = checked_cast<int>(claim._end);
278 if (UseCompressedOops) {
279 process_array_chunk_work<narrowOop>(new_obj, start, end);
280 } else {
281 process_array_chunk_work<oop>(new_obj, start, end);
282 }
283 }
284
285 void PSPromotionManager::push_objArray(oop old_obj, oop new_obj) {
286 assert(old_obj->is_forwarded(), "precondition");
287 assert(old_obj->forwardee() == new_obj, "precondition");
288 assert(new_obj->is_objArray(), "precondition");
289
290 objArrayOop to_array = objArrayOop(new_obj);
291 size_t array_length = to_array->length();
292 size_t initial_chunk_size =
293 // The source array is unused when processing states.
294 _partial_array_splitter.start(&_claimed_stack_depth, nullptr, to_array, array_length);
295 int end = checked_cast<int>(initial_chunk_size);
296 if (UseCompressedOops) {
297 process_array_chunk_work<narrowOop>(to_array, 0, end);
298 } else {
299 process_array_chunk_work<oop>(to_array, 0, end);
300 }
301 }
302
303 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
304 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
305
306 // Attempt to CAS in the header.
307 // This tests if the header is still the same as when
308 // this started. If it is the same (i.e., no forwarding
309 // pointer has been installed), then this thread owns
310 // it.
311 if (obj->forward_to_self_atomic(obj_mark) == nullptr) {
312 // We won any races, we "own" this object.
313 assert(obj == obj->forwardee(), "Sanity");
314
315 _promotion_failed_info.register_copy_failure(obj->size());
316
317 ContinuationGCSupport::transform_stack_chunk(obj);
318
319 push_contents(obj);
320
321 // Save the markWord of promotion-failed objs in _preserved_marks for later
322 // restoration. This way we don't have to walk the young-gen to locate
323 // these promotion-failed objs.
324 _preserved_marks->push_always(obj, obj_mark);
325 } else {
326 // We lost, someone else "owns" this object
327 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
328
329 // No unallocation to worry about.
330 obj = obj->forwardee();
331 }
332
333 return obj;
334 }