1 /*
2 * Copyright (c) 2002, 2024, 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 "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/partialArrayState.hpp"
35 #include "gc/shared/partialArrayTaskStepper.inline.hpp"
36 #include "gc/shared/preservedMarks.inline.hpp"
37 #include "gc/shared/taskqueue.inline.hpp"
38 #include "logging/log.hpp"
39 #include "logging/logStream.hpp"
40 #include "memory/allocation.inline.hpp"
41 #include "memory/iterator.inline.hpp"
42 #include "memory/memRegion.hpp"
43 #include "memory/padded.inline.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "oops/access.inline.hpp"
46 #include "oops/compressedOops.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 PartialArrayStateAllocator* PSPromotionManager::_partial_array_state_allocator = 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 // To prevent false sharing, we pad the PSPromotionManagers
65 // and make sure that the first instance starts at a cache line.
66 assert(_manager_array == nullptr, "Attempt to initialize twice");
67 _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
68
69 assert(_partial_array_state_allocator == nullptr, "Attempt to initialize twice");
70 _partial_array_state_allocator
71 = new PartialArrayStateAllocator(ParallelGCThreads);
72
73 _stack_array_depth = new PSScannerTasksQueueSet(ParallelGCThreads);
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 _manager_array[i]._partial_array_state_allocator_index = i;
79 }
80 // The VMThread gets its own PSPromotionManager, which is not available
81 // for work stealing.
82
83 assert(_preserved_marks_set == nullptr, "Attempt to initialize twice");
84 _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
85 _preserved_marks_set->init(promotion_manager_num);
86 for (uint i = 0; i < promotion_manager_num; i += 1) {
87 _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
88 }
89 }
90
91 // Helper functions to get around the circular dependency between
92 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
93 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
94 return PSScavenge::should_scavenge(p, check_to_space);
95 }
96 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
97 return PSScavenge::should_scavenge(p, check_to_space);
98 }
99
100 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
101 assert(index < ParallelGCThreads, "index out of range");
102 assert(_manager_array != nullptr, "Sanity");
103 return &_manager_array[index];
104 }
105
106 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
107 assert(_manager_array != nullptr, "Sanity");
108 return &_manager_array[0];
109 }
110
111 void PSPromotionManager::pre_scavenge() {
112 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
113
114 _preserved_marks_set->assert_empty();
115 _young_space = heap->young_gen()->to_space();
116
117 for(uint i=0; i<ParallelGCThreads; i++) {
118 manager_array(i)->reset();
119 }
120 }
121
122 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
123 bool promotion_failure_occurred = false;
124
125 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
126 for (uint i = 0; i < ParallelGCThreads; i++) {
127 PSPromotionManager* manager = manager_array(i);
128 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
129 if (manager->_promotion_failed_info.has_failed()) {
130 gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
131 promotion_failure_occurred = true;
132 }
133 manager->flush_labs();
134 manager->flush_string_dedup_requests();
135 }
136 // All PartialArrayStates have been returned to the allocator, since the
137 // claimed_stack_depths are all empty. Leave them there for use by future
138 // collections.
139
140 if (!promotion_failure_occurred) {
141 // If there was no promotion failure, the preserved mark stacks
142 // should be empty.
143 _preserved_marks_set->assert_empty();
144 }
145 return promotion_failure_occurred;
146 }
147
148 #if TASKQUEUE_STATS
149 void
150 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
151 #define FMT " " SIZE_FORMAT_W(10)
152 out->print_cr("%3u" FMT FMT FMT FMT,
153 i, _array_chunk_pushes, _array_chunk_steals,
154 _arrays_chunked, _array_chunks_processed);
155 #undef FMT
156 }
157
158 static const char* const pm_stats_hdr[] = {
159 " ----partial array---- arrays array",
160 "thr push steal chunked chunks",
161 "--- ---------- ---------- ---------- ----------"
162 };
163
164 void PSPromotionManager::print_taskqueue_stats() {
165 if (!log_is_enabled(Trace, gc, task, stats)) {
166 return;
167 }
168 Log(gc, task, stats) log;
169 ResourceMark rm;
170 LogStream ls(log.trace());
171
172 stack_array_depth()->print_taskqueue_stats(&ls, "Oop Queue");
173
174 const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
175 for (uint i = 0; i < hlines; ++i) ls.print_cr("%s", pm_stats_hdr[i]);
176 for (uint i = 0; i < ParallelGCThreads; ++i) {
177 manager_array(i)->print_local_stats(&ls, i);
178 }
179 }
180
181 void PSPromotionManager::reset_stats() {
182 claimed_stack_depth()->stats.reset();
183 _array_chunk_pushes = _array_chunk_steals = 0;
184 _arrays_chunked = _array_chunks_processed = 0;
185 }
186 #endif // TASKQUEUE_STATS
187
188 // Most members are initialized either by initialize() or reset().
189 PSPromotionManager::PSPromotionManager()
190 : _partial_array_stepper(ParallelGCThreads, ParGCArrayScanChunk)
191 {
192 // We set the old lab's start array.
193 _old_lab.set_start_array(old_gen()->start_array());
194
195 if (ParallelGCThreads == 1) {
196 _target_stack_size = 0;
197 } else {
198 _target_stack_size = GCDrainStackTargetSize;
199 }
200
201 // Initialize to a bad value; fixed by initialize().
202 _partial_array_state_allocator_index = UINT_MAX;
203
204 // let's choose 1.5x the chunk size
205 _min_array_size_for_chunking = (3 * ParGCArrayScanChunk / 2);
206
207 _preserved_marks = nullptr;
208
209 reset();
210 }
211
212 void PSPromotionManager::reset() {
213 assert(stacks_empty(), "reset of non-empty stack");
214
215 // We need to get an assert in here to make sure the labs are always flushed.
216
217 // Do not prefill the LAB's, save heap wastage!
218 HeapWord* lab_base = young_space()->top();
219 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
220 _young_gen_is_full = false;
221
222 lab_base = old_gen()->object_space()->top();
223 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
224 _old_gen_is_full = false;
225
226 _promotion_failed_info.reset();
227
228 TASKQUEUE_STATS_ONLY(reset_stats());
229 }
230
231 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
232 assert(_preserved_marks == nullptr, "do not set it twice");
233 _preserved_marks = preserved_marks;
234 }
235
236 void PSPromotionManager::restore_preserved_marks() {
237 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
238 }
239
240 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
241 const uint threshold = totally_drain ? 0
242 : _target_stack_size;
243
244 PSScannerTasksQueue* const tq = claimed_stack_depth();
245 do {
246 ScannerTask task;
247
248 // Drain overflow stack first, so other threads can steal from
249 // claimed stack while we work.
250 while (tq->pop_overflow(task)) {
251 if (!tq->try_push_to_taskqueue(task)) {
252 process_popped_location_depth(task);
253 }
254 }
255
256 while (tq->pop_local(task, threshold)) {
257 process_popped_location_depth(task);
258 }
259 } while (!tq->overflow_empty());
260
261 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
262 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
263 assert(tq->overflow_empty(), "Sanity");
264 }
265
266 void PSPromotionManager::flush_labs() {
267 assert(stacks_empty(), "Attempt to flush lab with live stack");
268
269 // If either promotion lab fills up, we can flush the
270 // lab but not refill it, so check first.
271 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
272 if (!_young_lab.is_flushed())
273 _young_lab.flush();
274
275 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
276 if (!_old_lab.is_flushed())
277 _old_lab.flush();
278
279 // Let PSScavenge know if we overflowed
280 if (_young_gen_is_full) {
281 PSScavenge::set_survivor_overflow(true);
282 }
283 }
284
285 template <class T> void PSPromotionManager::process_array_chunk_work(
286 oop obj,
287 int start, int end) {
288 assert(start <= end, "invariant");
289 T* const base = (T*)objArrayOop(obj)->base();
290 T* p = base + start;
291 T* const chunk_end = base + end;
292 while (p < chunk_end) {
293 claim_or_forward_depth(p);
294 ++p;
295 }
296 }
297
298 void PSPromotionManager::process_array_chunk(PartialArrayState* state) {
299 TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
300
301 // Claim a chunk. Push additional tasks before processing the claimed
302 // chunk to allow other workers to steal while we're processing.
303 PartialArrayTaskStepper::Step step = _partial_array_stepper.next(state);
304 if (step._ncreate > 0) {
305 state->add_references(step._ncreate);
306 for (uint i = 0; i < step._ncreate; ++i) {
307 push_depth(ScannerTask(state));
308 }
309 TASKQUEUE_STATS_ONLY(_array_chunk_pushes += step._ncreate);
310 }
311 int start = checked_cast<int>(step._index);
312 int end = checked_cast<int>(step._index + _partial_array_stepper.chunk_size());
313 assert(start < end, "invariant");
314 if (UseCompressedOops) {
315 process_array_chunk_work<narrowOop>(state->destination(), start, end);
316 } else {
317 process_array_chunk_work<oop>(state->destination(), start, end);
318 }
319 // Release reference to state, now that we're done with it.
320 _partial_array_state_allocator->release(_partial_array_state_allocator_index, state);
321 }
322
323 void PSPromotionManager::push_objArray(oop old_obj, oop new_obj) {
324 assert(old_obj->is_objArray(), "precondition");
325 assert(old_obj->is_forwarded(), "precondition");
326 assert(old_obj->forwardee() == new_obj, "precondition");
327 assert(new_obj->is_objArray(), "precondition");
328
329 size_t array_length = objArrayOop(new_obj)->length();
330 PartialArrayTaskStepper::Step step = _partial_array_stepper.start(array_length);
331
332 if (step._ncreate > 0) {
333 TASKQUEUE_STATS_ONLY(++_arrays_chunked);
334 PartialArrayState* state =
335 _partial_array_state_allocator->allocate(_partial_array_state_allocator_index,
336 old_obj, new_obj,
337 step._index,
338 array_length,
339 step._ncreate);
340 for (uint i = 0; i < step._ncreate; ++i) {
341 push_depth(ScannerTask(state));
342 }
343 TASKQUEUE_STATS_ONLY(_array_chunk_pushes += step._ncreate);
344 }
345 if (UseCompressedOops) {
346 process_array_chunk_work<narrowOop>(new_obj, 0, checked_cast<int>(step._index));
347 } else {
348 process_array_chunk_work<oop>(new_obj, 0, checked_cast<int>(step._index));
349 }
350 }
351
352 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
353 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
354
355 // Attempt to CAS in the header.
356 // This tests if the header is still the same as when
357 // this started. If it is the same (i.e., no forwarding
358 // pointer has been installed), then this thread owns
359 // it.
360 if (obj->forward_to_atomic(obj, obj_mark) == nullptr) {
361 // We won any races, we "own" this object.
362 assert(obj == obj->forwardee(), "Sanity");
363
364 _promotion_failed_info.register_copy_failure(obj->size());
365
366 ContinuationGCSupport::transform_stack_chunk(obj);
367
368 push_contents(obj);
369
370 // Save the markWord of promotion-failed objs in _preserved_marks for later
371 // restoration. This way we don't have to walk the young-gen to locate
372 // these promotion-failed objs.
373 _preserved_marks->push_always(obj, obj_mark);
374 } else {
375 // We lost, someone else "owns" this object
376 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
377
378 // No unallocation to worry about.
379 obj = obj->forwardee();
380 }
381
382 return obj;
383 }