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.
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/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 "oops/flatArrayKlass.inline.hpp"
48 #include "utilities/checkedCast.hpp"
49
50 PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = nullptr;
51 PSPromotionManager::PSScannerTasksQueueSet* PSPromotionManager::_stack_array_depth = nullptr;
52 PreservedMarksSet* PSPromotionManager::_preserved_marks_set = nullptr;
53 PSOldGen* PSPromotionManager::_old_gen = nullptr;
54 MutableSpace* PSPromotionManager::_young_space = nullptr;
55 PartialArrayStateAllocator* PSPromotionManager::_partial_array_state_allocator = nullptr;
56
57 void PSPromotionManager::initialize() {
58 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
59
60 _old_gen = heap->old_gen();
61 _young_space = heap->young_gen()->to_space();
62
63 const uint promotion_manager_num = ParallelGCThreads;
64
65 // To prevent false sharing, we pad the PSPromotionManagers
66 // and make sure that the first instance starts at a cache line.
67 assert(_manager_array == nullptr, "Attempt to initialize twice");
68 _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(promotion_manager_num);
69
70 assert(_partial_array_state_allocator == nullptr, "Attempt to initialize twice");
71 _partial_array_state_allocator
72 = new PartialArrayStateAllocator(ParallelGCThreads);
73
74 _stack_array_depth = new PSScannerTasksQueueSet(ParallelGCThreads);
75
76 // Create and register the PSPromotionManager(s) for the worker threads.
77 for(uint i=0; i<ParallelGCThreads; i++) {
78 stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
79 _manager_array[i]._partial_array_state_allocator_index = i;
80 }
81 // The VMThread gets its own PSPromotionManager, which is not available
82 // for work stealing.
83
84 assert(_preserved_marks_set == nullptr, "Attempt to initialize twice");
85 _preserved_marks_set = new PreservedMarksSet(true /* in_c_heap */);
86 _preserved_marks_set->init(promotion_manager_num);
87 for (uint i = 0; i < promotion_manager_num; i += 1) {
88 _manager_array[i].register_preserved_marks(_preserved_marks_set->get(i));
89 }
90 }
91
92 // Helper functions to get around the circular dependency between
93 // psScavenge.inline.hpp and psPromotionManager.inline.hpp.
94 bool PSPromotionManager::should_scavenge(oop* p, bool check_to_space) {
95 return PSScavenge::should_scavenge(p, check_to_space);
96 }
97 bool PSPromotionManager::should_scavenge(narrowOop* p, bool check_to_space) {
98 return PSScavenge::should_scavenge(p, check_to_space);
99 }
100
101 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(uint index) {
102 assert(index < ParallelGCThreads, "index out of range");
103 assert(_manager_array != nullptr, "Sanity");
104 return &_manager_array[index];
105 }
106
107 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
108 assert(_manager_array != nullptr, "Sanity");
109 return &_manager_array[0];
110 }
111
112 void PSPromotionManager::pre_scavenge() {
113 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
114
115 _preserved_marks_set->assert_empty();
116 _young_space = heap->young_gen()->to_space();
117
118 for(uint i=0; i<ParallelGCThreads; i++) {
119 manager_array(i)->reset();
120 }
121 }
122
123 bool PSPromotionManager::post_scavenge(YoungGCTracer& gc_tracer) {
124 bool promotion_failure_occurred = false;
125
126 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
127 for (uint i = 0; i < ParallelGCThreads; i++) {
128 PSPromotionManager* manager = manager_array(i);
129 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
130 if (manager->_promotion_failed_info.has_failed()) {
131 gc_tracer.report_promotion_failed(manager->_promotion_failed_info);
132 promotion_failure_occurred = true;
133 }
134 manager->flush_labs();
135 manager->flush_string_dedup_requests();
136 }
137 // All PartialArrayStates have been returned to the allocator, since the
138 // claimed_stack_depths are all empty. Leave them there for use by future
139 // collections.
140
141 if (!promotion_failure_occurred) {
142 // If there was no promotion failure, the preserved mark stacks
143 // should be empty.
144 _preserved_marks_set->assert_empty();
145 }
146 return promotion_failure_occurred;
147 }
148
149 #if TASKQUEUE_STATS
150 void
151 PSPromotionManager::print_local_stats(outputStream* const out, uint i) const {
152 #define FMT " " SIZE_FORMAT_W(10)
153 out->print_cr("%3u" FMT FMT FMT FMT,
154 i, _array_chunk_pushes, _array_chunk_steals,
155 _arrays_chunked, _array_chunks_processed);
156 #undef FMT
157 }
158
159 static const char* const pm_stats_hdr[] = {
160 " ----partial array---- arrays array",
161 "thr push steal chunked chunks",
162 "--- ---------- ---------- ---------- ----------"
163 };
164
165 void PSPromotionManager::print_taskqueue_stats() {
166 if (!log_is_enabled(Trace, gc, task, stats)) {
167 return;
168 }
169 Log(gc, task, stats) log;
170 ResourceMark rm;
171 LogStream ls(log.trace());
172
173 stack_array_depth()->print_taskqueue_stats(&ls, "Oop Queue");
174
175 const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
176 for (uint i = 0; i < hlines; ++i) ls.print_cr("%s", pm_stats_hdr[i]);
177 for (uint i = 0; i < ParallelGCThreads; ++i) {
178 manager_array(i)->print_local_stats(&ls, i);
179 }
180 }
181
182 void PSPromotionManager::reset_stats() {
183 claimed_stack_depth()->stats.reset();
184 _array_chunk_pushes = _array_chunk_steals = 0;
185 _arrays_chunked = _array_chunks_processed = 0;
186 }
187 #endif // TASKQUEUE_STATS
188
189 // Most members are initialized either by initialize() or reset().
190 PSPromotionManager::PSPromotionManager()
191 : _partial_array_stepper(ParallelGCThreads, ParGCArrayScanChunk)
192 {
193 // We set the old lab's start array.
194 _old_lab.set_start_array(old_gen()->start_array());
195
196 if (ParallelGCThreads == 1) {
197 _target_stack_size = 0;
198 } else {
199 _target_stack_size = GCDrainStackTargetSize;
200 }
201
202 // Initialize to a bad value; fixed by initialize().
203 _partial_array_state_allocator_index = UINT_MAX;
204
205 // let's choose 1.5x the chunk size
206 _min_array_size_for_chunking = (3 * ParGCArrayScanChunk / 2);
207
208 _preserved_marks = nullptr;
209
210 reset();
211 }
212
213 void PSPromotionManager::reset() {
214 assert(stacks_empty(), "reset of non-empty stack");
215
216 // We need to get an assert in here to make sure the labs are always flushed.
217
218 // Do not prefill the LAB's, save heap wastage!
219 HeapWord* lab_base = young_space()->top();
220 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
221 _young_gen_is_full = false;
222
223 lab_base = old_gen()->object_space()->top();
224 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
225 _old_gen_is_full = false;
226
227 _promotion_failed_info.reset();
228
229 TASKQUEUE_STATS_ONLY(reset_stats());
230 }
231
232 void PSPromotionManager::register_preserved_marks(PreservedMarks* preserved_marks) {
233 assert(_preserved_marks == nullptr, "do not set it twice");
234 _preserved_marks = preserved_marks;
235 }
236
237 void PSPromotionManager::restore_preserved_marks() {
238 _preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
239 }
240
241 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
242 const uint threshold = totally_drain ? 0
243 : _target_stack_size;
244
245 PSScannerTasksQueue* const tq = claimed_stack_depth();
246 do {
247 ScannerTask task;
248
249 // Drain overflow stack first, so other threads can steal from
250 // claimed stack while we work.
251 while (tq->pop_overflow(task)) {
252 if (!tq->try_push_to_taskqueue(task)) {
253 process_popped_location_depth(task);
254 }
255 }
256
257 while (tq->pop_local(task, threshold)) {
258 process_popped_location_depth(task);
259 }
260 } while (!tq->overflow_empty());
261
262 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
263 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
264 assert(tq->overflow_empty(), "Sanity");
265 }
266
267 void PSPromotionManager::flush_labs() {
268 assert(stacks_empty(), "Attempt to flush lab with live stack");
269
270 // If either promotion lab fills up, we can flush the
271 // lab but not refill it, so check first.
272 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
273 if (!_young_lab.is_flushed())
274 _young_lab.flush();
275
276 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
277 if (!_old_lab.is_flushed())
278 _old_lab.flush();
279
280 // Let PSScavenge know if we overflowed
281 if (_young_gen_is_full) {
282 PSScavenge::set_survivor_overflow(true);
283 }
284 }
285
286 template <class T> void PSPromotionManager::process_array_chunk_work(
287 oop obj,
288 int start, int end) {
289 assert(start <= end, "invariant");
290 T* const base = (T*)objArrayOop(obj)->base();
291 T* p = base + start;
292 T* const chunk_end = base + end;
293 while (p < chunk_end) {
294 claim_or_forward_depth(p);
295 ++p;
296 }
297 }
298
299 void PSPromotionManager::process_array_chunk(PartialArrayState* state) {
300 TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
301
302 // Claim a chunk. Push additional tasks before processing the claimed
303 // chunk to allow other workers to steal while we're processing.
304 PartialArrayTaskStepper::Step step = _partial_array_stepper.next(state);
305 if (step._ncreate > 0) {
306 state->add_references(step._ncreate);
307 for (uint i = 0; i < step._ncreate; ++i) {
308 push_depth(ScannerTask(state));
309 }
310 TASKQUEUE_STATS_ONLY(_array_chunk_pushes += step._ncreate);
311 }
312 int start = checked_cast<int>(step._index);
313 int end = checked_cast<int>(step._index + _partial_array_stepper.chunk_size());
314 assert(start < end, "invariant");
315 if (UseCompressedOops) {
316 process_array_chunk_work<narrowOop>(state->destination(), start, end);
317 } else {
318 process_array_chunk_work<oop>(state->destination(), start, end);
319 }
320 // Release reference to state, now that we're done with it.
321 _partial_array_state_allocator->release(_partial_array_state_allocator_index, state);
322 }
323
324 void PSPromotionManager::push_objArray(oop old_obj, oop new_obj) {
325 assert(old_obj->is_objArray(), "precondition");
326 assert(old_obj->is_forwarded(), "precondition");
327 assert(old_obj->forwardee() == new_obj, "precondition");
328 assert(new_obj->is_objArray(), "precondition");
329
330 size_t array_length = objArrayOop(new_obj)->length();
331 PartialArrayTaskStepper::Step step = _partial_array_stepper.start(array_length);
332
333 if (step._ncreate > 0) {
334 TASKQUEUE_STATS_ONLY(++_arrays_chunked);
335 PartialArrayState* state =
336 _partial_array_state_allocator->allocate(_partial_array_state_allocator_index,
337 old_obj, new_obj,
338 step._index,
339 array_length,
340 step._ncreate);
341 for (uint i = 0; i < step._ncreate; ++i) {
342 push_depth(ScannerTask(state));
343 }
344 TASKQUEUE_STATS_ONLY(_array_chunk_pushes += step._ncreate);
345 }
346 if (UseCompressedOops) {
347 process_array_chunk_work<narrowOop>(new_obj, 0, checked_cast<int>(step._index));
348 } else {
349 process_array_chunk_work<oop>(new_obj, 0, checked_cast<int>(step._index));
350 }
351 }
352
353 oop PSPromotionManager::oop_promotion_failed(oop obj, markWord obj_mark) {
354 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
355
356 // Attempt to CAS in the header.
357 // This tests if the header is still the same as when
358 // this started. If it is the same (i.e., no forwarding
359 // pointer has been installed), then this thread owns
360 // it.
361 if (obj->forward_to_atomic(obj, obj_mark) == nullptr) {
362 // We won any races, we "own" this object.
363 assert(obj == obj->forwardee(), "Sanity");
364
365 _promotion_failed_info.register_copy_failure(obj->size());
366
367 ContinuationGCSupport::transform_stack_chunk(obj);
368
369 push_contents(obj);
370
371 // Save the markWord of promotion-failed objs in _preserved_marks for later
372 // restoration. This way we don't have to walk the young-gen to locate
373 // these promotion-failed objs.
374 _preserved_marks->push_always(obj, obj_mark);
375 } else {
376 // We lost, someone else "owns" this object
377 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
378
379 // No unallocation to worry about.
380 obj = obj->forwardee();
381 }
382
383 return obj;
384 }