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 "oops/flatArrayKlass.inline.hpp"
47 #include "utilities/checkedCast.hpp"
48
49 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = nullptr;
50 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = nullptr;
51 PreservedMarksSet* PSPromotionManager::_preserved_marks_set = nullptr;
52 PSOldGen* PSPromotionManager::_old_gen = nullptr;
53 MutableSpace* PSPromotionManager::_young_space = nullptr;
54 PartialArrayStateManager* PSPromotionManager::_partial_array_state_manager = nullptr;
55
56 void PSPromotionManager::initialize() {
57 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
58
59 _old_gen = heap->old_gen();
60 _young_space = heap->young_gen()->to_space();
61
62 const uint promotion_manager_num = ParallelGCThreads;
63
64 assert(_partial_array_state_manager == nullptr, "Attempt to initialize twice");
65 _partial_array_state_manager
66 = new PartialArrayStateManager(promotion_manager_num);
67
68 // To prevent false sharing, we pad the PSPromotionManagers
69 // and make sure that the first instance starts at a cache line.
70 assert(_manager_array == nullptr, "Attempt to initialize twice");
71 _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
72
73 _stack_array_depth = new PSScannerTasksQueueSet(promotion_manager_num);
74
75 // Create and register the PSPromotionManager(s) for the worker threads.
76 for(uint i=0; i<ParallelGCThreads; i++) {
77 stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
78 }
79 // The VMThread gets its own PSPromotionManager, which is not available
80 // for work stealing.
81
82 assert(_preserved_marks_set == nullptr, "Attempt to initialize twice");
83 _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
84 _preserved_marks_set->init(promotion_manager_num);
85 for (uint i = 0; i < promotion_manager_num; i += 1) {
86 _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
87 }
88 }
89
90 // Helper functions to get around the circular dependency between
91 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
92 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
93 return PSScavenge::should_scavenge(p, check_to_space);
94 }
95 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
96 return PSScavenge::should_scavenge(p, check_to_space);
97 }
98
99 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
100 assert(index < ParallelGCThreads, "index out of range");
101 assert(_manager_array != nullptr, "Sanity");
102 return &_manager_array[index];
103 }
104
105 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
106 assert(_manager_array != nullptr, "Sanity");
107 return &_manager_array[0];
108 }
109
110 void PSPromotionManager::pre_scavenge() {
111 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
112
113 _preserved_marks_set->assert_empty();
114 _young_space = heap->young_gen()->to_space();
115
116 for(uint i=0; i<ParallelGCThreads; i++) {
117 manager_array(i)->reset();
118 }
119 }
120
121 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
122 bool promotion_failure_occurred = false;
123
124 TASKQUEUE_STATS_ONLY(print_and_reset_taskqueue_stats());
125 for (uint i = 0; i < ParallelGCThreads; i++) {
126 PSPromotionManager* manager = manager_array(i);
127 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
128 if (manager->_promotion_failed_info.has_failed()) {
129 gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
130 promotion_failure_occurred = true;
131 }
132 manager->flush_labs();
133 manager->flush_string_dedup_requests();
134 }
135 // All PartialArrayStates have been returned to the allocator, since the
136 // claimed_stack_depths are all empty. Leave them there for use by future
137 // collections.
138
139 if (!promotion_failure_occurred) {
140 // If there was no promotion failure, the preserved mark stacks
141 // should be empty.
142 _preserved_marks_set->assert_empty();
143 }
144 return promotion_failure_occurred;
145 }
146
147 #if TASKQUEUE_STATS
148
149 void PSPromotionManager::print_and_reset_taskqueue_stats() {
150 stack_array_depth()->print_and_reset_taskqueue_stats("Oop Queue");
151
152 auto get_pa_stats = [&](uint i) {
153 return manager_array(i)->partial_array_task_stats();
154 };
155 PartialArrayTaskStats::log_set(ParallelGCThreads, get_pa_stats,
156 "Partial Array Task Stats");
157 for (uint i = 0; i < ParallelGCThreads; ++i) {
158 get_pa_stats(i)->reset();
159 }
160 }
161
162 PartialArrayTaskStats* PSPromotionManager::partial_array_task_stats() {
163 return _partial_array_splitter.stats();
164 }
165
166 #endif // TASKQUEUE_STATS
167
168 // Most members are initialized either by initialize() or reset().
169 PSPromotionManager::PSPromotionManager()
170 : _partial_array_splitter(_partial_array_state_manager, ParallelGCThreads)
171 {
172 // We set the old lab's start array.
173 _old_lab.set_start_array(old_gen()->start_array());
174
175 if (ParallelGCThreads == 1) {
176 _target_stack_size = 0;
177 } else {
178 _target_stack_size = GCDrainStackTargetSize;
179 }
180
181 // let's choose 1.5x the chunk size
182 _min_array_size_for_chunking = (3 * ParGCArrayScanChunk / 2);
183
184 _preserved_marks = nullptr;
185
186 reset();
187 }
188
189 void PSPromotionManager::reset() {
190 assert(stacks_empty(), "reset of non-empty stack");
191
192 // We need to get an assert in here to make sure the labs are always flushed.
193
194 // Do not prefill the LAB's, save heap wastage!
195 HeapWord* lab_base = young_space()->top();
196 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
197 _young_gen_is_full = false;
198
199 lab_base = old_gen()->object_space()->top();
200 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
201 _old_gen_is_full = false;
202
203 _promotion_failed_info.reset();
204 }
205
206 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
207 assert(_preserved_marks == nullptr, "do not set it twice");
208 _preserved_marks = preserved_marks;
209 }
210
211 void PSPromotionManager::restore_preserved_marks() {
212 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
213 }
214
215 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
216 const uint threshold = totally_drain ? 0
217 : _target_stack_size;
218
219 PSScannerTasksQueue* const tq = claimed_stack_depth();
220 do {
221 ScannerTask task;
222
223 // Drain overflow stack first, so other threads can steal from
224 // claimed stack while we work.
225 while (tq->pop_overflow(task)) {
226 if (!tq->try_push_to_taskqueue(task)) {
227 process_popped_location_depth(task, false);
228 }
229 }
230
231 while (tq->pop_local(task, threshold)) {
232 process_popped_location_depth(task, false);
233 }
234 } while (!tq->overflow_empty());
235
236 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
237 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
238 assert(tq->overflow_empty(), "Sanity");
239 }
240
241 void PSPromotionManager::flush_labs() {
242 assert(stacks_empty(), "Attempt to flush lab with live stack");
243
244 // If either promotion lab fills up, we can flush the
245 // lab but not refill it, so check first.
246 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
247 if (!_young_lab.is_flushed())
248 _young_lab.flush();
249
250 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
251 if (!_old_lab.is_flushed())
252 _old_lab.flush();
253
254 // Let PSScavenge know if we overflowed
255 if (_young_gen_is_full) {
256 PSScavenge::set_survivor_overflow(true);
257 }
258 }
259
260 template <class T>
261 void PSPromotionManager::process_array_chunk_work(oop obj, int start, int end) {
262 assert(start <= end, "invariant");
263 T* const base = (T*)objArrayOop(obj)->base();
264 T* p = base + start;
265 T* const chunk_end = base + end;
266 while (p < chunk_end) {
267 claim_or_forward_depth(p);
268 ++p;
269 }
270 }
271
272 void PSPromotionManager::process_array_chunk(PartialArrayState* state, bool stolen) {
273 // Access before release by claim().
274 oop new_obj = state->destination();
275 PartialArraySplitter::Claim claim =
276 _partial_array_splitter.claim(state, &_claimed_stack_depth, stolen);
277 int start = checked_cast<int>(claim._start);
278 int end = checked_cast<int>(claim._end);
279 if (UseCompressedOops) {
280 process_array_chunk_work<narrowOop>(new_obj, start, end);
281 } else {
282 process_array_chunk_work<oop>(new_obj, start, end);
283 }
284 }
285
286 void PSPromotionManager::push_objArray(oop old_obj, oop new_obj) {
287 assert(old_obj->is_forwarded(), "precondition");
288 assert(old_obj->forwardee() == new_obj, "precondition");
289 assert(new_obj->is_objArray(), "precondition");
290
291 objArrayOop to_array = objArrayOop(new_obj);
292 size_t array_length = to_array->length();
293 size_t initial_chunk_size =
294 // The source array is unused when processing states.
295 _partial_array_splitter.start(&_claimed_stack_depth, nullptr, to_array, array_length);
296 int end = checked_cast<int>(initial_chunk_size);
297 if (UseCompressedOops) {
298 process_array_chunk_work<narrowOop>(to_array, 0, end);
299 } else {
300 process_array_chunk_work<oop>(to_array, 0, end);
301 }
302 }
303
304 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
305 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
306
307 // Attempt to CAS in the header.
308 // This tests if the header is still the same as when
309 // this started. If it is the same (i.e., no forwarding
310 // pointer has been installed), then this thread owns
311 // it.
312 if (obj->forward_to_self_atomic(obj_mark) == nullptr) {
313 // We won any races, we "own" this object.
314 assert(obj == obj->forwardee(), "Sanity");
315
316 _promotion_failed_info.register_copy_failure(obj->size());
317
318 ContinuationGCSupport::transform_stack_chunk(obj);
319
320 push_contents(obj);
321
322 // Save the markWord of promotion-failed objs in _preserved_marks for later
323 // restoration. This way we don't have to walk the young-gen to locate
324 // these promotion-failed objs.
325 _preserved_marks->push_always(obj, obj_mark);
326 } else {
327 // We lost, someone else "owns" this object
328 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
329
330 // No unallocation to worry about.
331 obj = obj->forwardee();
332 }
333
334 return obj;
335 }