1 /*
2 * Copyright (c) 2014, 2019, 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 "gc/g1/g1Allocator.inline.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1CollectionSet.hpp"
29 #include "gc/g1/g1OopClosures.inline.hpp"
30 #include "gc/g1/g1ParScanThreadState.inline.hpp"
31 #include "gc/g1/g1RootClosures.hpp"
32 #include "gc/g1/g1StringDedup.hpp"
33 #include "gc/shared/gcTrace.hpp"
34 #include "gc/shared/taskqueue.inline.hpp"
35 #include "memory/allocation.inline.hpp"
36 #include "oops/access.inline.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/prefetch.inline.hpp"
39
40 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h,
41 uint worker_id,
42 size_t young_cset_length,
43 size_t optional_cset_length)
44 : _g1h(g1h),
45 _refs(g1h->task_queue(worker_id)),
46 _dcq(&g1h->dirty_card_queue_set()),
47 _ct(g1h->card_table()),
48 _closures(NULL),
49 _plab_allocator(NULL),
50 _age_table(false),
51 _tenuring_threshold(g1h->policy()->tenuring_threshold()),
52 _scanner(g1h, this),
53 _worker_id(worker_id),
54 _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1),
55 _stack_trim_lower_threshold(GCDrainStackTargetSize),
56 _trim_ticks(),
57 _old_gen_is_full(false),
58 _num_optional_regions(optional_cset_length)
59 {
60 // we allocate G1YoungSurvRateNumRegions plus one entries, since
61 // we "sacrifice" entry 0 to keep track of surviving bytes for
62 // non-young regions (where the age is -1)
63 // We also add a few elements at the beginning and at the end in
64 // an attempt to eliminate cache contention
65 size_t real_length = 1 + young_cset_length;
66 size_t array_length = PADDING_ELEM_NUM +
67 real_length +
68 PADDING_ELEM_NUM;
69 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
70 if (_surviving_young_words_base == NULL)
71 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
72 "Not enough space for young surv histo.");
73 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
74 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
75
76 _plab_allocator = new G1PLABAllocator(_g1h->allocator());
77
78 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
79 // The dest for Young is used when the objects are aged enough to
80 // need to be moved to the next space.
81 _dest[InCSetState::Young] = InCSetState::Old;
82 _dest[InCSetState::Old] = InCSetState::Old;
83
84 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
85
86 _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions];
87 }
88
89 // Pass locally gathered statistics to global state.
90 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
91 _dcq.flush();
92 // Update allocation statistics.
93 _plab_allocator->flush_and_retire_stats();
94 _g1h->policy()->record_age_table(&_age_table);
95
96 uint length = _g1h->collection_set()->young_region_length();
97 for (uint region_index = 0; region_index < length; region_index++) {
98 surviving_young_words[region_index] += _surviving_young_words[region_index];
99 }
100 }
101
102 G1ParScanThreadState::~G1ParScanThreadState() {
103 delete _plab_allocator;
104 delete _closures;
105 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
106 delete[] _oops_into_optional_regions;
107 }
108
109 size_t G1ParScanThreadState::lab_waste_words() const {
110 return _plab_allocator->waste();
111 }
112
113 size_t G1ParScanThreadState::lab_undo_waste_words() const {
114 return _plab_allocator->undo_waste();
115 }
116
117 #ifdef ASSERT
118 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
119 assert(ref != NULL, "invariant");
120 assert(UseCompressedOops, "sanity");
121 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
122 oop p = RawAccess<>::oop_load(ref);
123 assert(_g1h->is_in_g1_reserved(p),
124 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
125 return true;
126 }
127
128 bool G1ParScanThreadState::verify_ref(oop* ref) const {
129 assert(ref != NULL, "invariant");
130 if (has_partial_array_mask(ref)) {
131 // Must be in the collection set--it's already been copied.
132 oop p = clear_partial_array_mask(ref);
133 assert(_g1h->is_in_cset(p),
134 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
135 } else {
136 oop p = RawAccess<>::oop_load(ref);
137 assert(_g1h->is_in_g1_reserved(p),
138 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
139 }
140 return true;
141 }
142
143 bool G1ParScanThreadState::verify_task(StarTask ref) const {
144 if (ref.is_narrow()) {
145 return verify_ref((narrowOop*) ref);
146 } else {
147 return verify_ref((oop*) ref);
148 }
149 }
150 #endif // ASSERT
151
152 void G1ParScanThreadState::trim_queue() {
153 StarTask ref;
154 do {
155 // Fully drain the queue.
156 trim_queue_to_threshold(0);
157 } while (!_refs->is_empty());
158 }
159
160 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
161 InCSetState* dest,
162 size_t word_sz,
163 bool previous_plab_refill_failed) {
164 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());
165 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
166
167 // Right now we only have two types of regions (young / old) so
168 // let's keep the logic here simple. We can generalize it when necessary.
169 if (dest->is_young()) {
170 bool plab_refill_in_old_failed = false;
171 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old,
172 word_sz,
173 &plab_refill_in_old_failed);
174 // Make sure that we won't attempt to copy any other objects out
175 // of a survivor region (given that apparently we cannot allocate
176 // any new ones) to avoid coming into this slow path again and again.
177 // Only consider failed PLAB refill here: failed inline allocations are
178 // typically large, so not indicative of remaining space.
179 if (previous_plab_refill_failed) {
180 _tenuring_threshold = 0;
181 }
182
183 if (obj_ptr != NULL) {
184 dest->set_old();
185 } else {
186 // We just failed to allocate in old gen. The same idea as explained above
187 // for making survivor gen unavailable for allocation applies for old gen.
188 _old_gen_is_full = plab_refill_in_old_failed;
189 }
190 return obj_ptr;
191 } else {
192 _old_gen_is_full = previous_plab_refill_failed;
193 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
194 // no other space to try.
195 return NULL;
196 }
197 }
198
199 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
200 if (state.is_young()) {
201 age = !m->has_displaced_mark_helper() ? m->age()
202 : m->displaced_mark_helper()->age();
203 if (age < _tenuring_threshold) {
204 return state;
205 }
206 }
207 return dest(state);
208 }
209
210 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,
211 oop const old, size_t word_sz, uint age,
212 HeapWord * const obj_ptr) const {
213 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state);
214 if (alloc_buf->contains(obj_ptr)) {
215 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
216 dest_state.value() == InCSetState::Old,
217 alloc_buf->word_sz() * HeapWordSize);
218 } else {
219 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
220 dest_state.value() == InCSetState::Old);
221 }
222 }
223
224 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
225 oop const old,
226 markOop const old_mark) {
227 const size_t word_sz = old->size();
228 HeapRegion* const from_region = _g1h->heap_region_containing(old);
229 // +1 to make the -1 indexes valid...
230 const int young_index = from_region->young_index_in_cset()+1;
231 assert( (from_region->is_young() && young_index > 0) ||
232 (!from_region->is_young() && young_index == 0), "invariant" );
233
234 uint age = 0;
235 InCSetState dest_state = next_state(state, old_mark, age);
236 // The second clause is to prevent premature evacuation failure in case there
237 // is still space in survivor, but old gen is full.
238 if (_old_gen_is_full && dest_state.is_old()) {
239 return handle_evacuation_failure_par(old, old_mark);
240 }
241 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz);
242
243 // PLAB allocations should succeed most of the time, so we'll
244 // normally check against NULL once and that's it.
245 if (obj_ptr == NULL) {
246 bool plab_refill_failed = false;
247 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed);
248 if (obj_ptr == NULL) {
249 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed);
250 if (obj_ptr == NULL) {
251 // This will either forward-to-self, or detect that someone else has
252 // installed a forwarding pointer.
253 return handle_evacuation_failure_par(old, old_mark);
254 }
255 }
256 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
257 // The events are checked individually as part of the actual commit
258 report_promotion_event(dest_state, old, word_sz, age, obj_ptr);
259 }
260 }
261
262 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
263 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
264
265 #ifndef PRODUCT
266 // Should this evacuation fail?
267 if (_g1h->evacuation_should_fail()) {
268 // Doing this after all the allocation attempts also tests the
269 // undo_allocation() method too.
270 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
271 return handle_evacuation_failure_par(old, old_mark);
272 }
273 #endif // !PRODUCT
274
275 // We're going to allocate linearly, so might as well prefetch ahead.
276 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
277
278 const oop obj = oop(obj_ptr);
279 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed);
280 if (forward_ptr == NULL) {
281 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
282
283 if (dest_state.is_young()) {
284 if (age < markOopDesc::max_age) {
285 age++;
286 }
287 if (old_mark->has_displaced_mark_helper()) {
288 // In this case, we have to install the mark word first,
289 // otherwise obj looks to be forwarded (the old mark word,
290 // which contains the forward pointer, was copied)
291 obj->set_mark_raw(old_mark);
292 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
293 old_mark->set_displaced_mark_helper(new_mark);
294 } else {
295 obj->set_mark_raw(old_mark->set_age(age));
296 }
297 _age_table.add(age, word_sz);
298 } else {
299 obj->set_mark_raw(old_mark);
300 }
301
302 if (G1StringDedup::is_enabled()) {
303 const bool is_from_young = state.is_young();
304 const bool is_to_young = dest_state.is_young();
305 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
306 "sanity");
307 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
308 "sanity");
309 G1StringDedup::enqueue_from_evacuation(is_from_young,
310 is_to_young,
311 _worker_id,
312 obj);
313 }
314
315 _surviving_young_words[young_index] += word_sz;
316
317 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
318 // We keep track of the next start index in the length field of
319 // the to-space object. The actual length can be found in the
320 // length field of the from-space object.
321 arrayOop(obj)->set_length(0);
322 oop* old_p = set_partial_array_mask(old);
323 do_oop_partial_array(old_p);
324 } else {
325 G1ScanInYoungSetter x(&_scanner, dest_state.is_young());
326 obj->oop_iterate_backwards(&_scanner);
327 }
328 return obj;
329 } else {
330 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
331 return forward_ptr;
332 }
333 }
334
335 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
336 assert(worker_id < _n_workers, "out of bounds access");
337 if (_states[worker_id] == NULL) {
338 _states[worker_id] =
339 new G1ParScanThreadState(_g1h, worker_id, _young_cset_length, _optional_cset_length);
340 }
341 return _states[worker_id];
342 }
343
344 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
345 assert(_flushed, "thread local state from the per thread states should have been flushed");
346 return _surviving_young_words_total;
347 }
348
349 void G1ParScanThreadStateSet::flush() {
350 assert(!_flushed, "thread local state from the per thread states should be flushed once");
351
352 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
353 G1ParScanThreadState* pss = _states[worker_index];
354
355 if (pss == NULL) {
356 continue;
357 }
358
359 pss->flush(_surviving_young_words_total);
360 delete pss;
361 _states[worker_index] = NULL;
362 }
363 _flushed = true;
364 }
365
366 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
367 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
368 G1ParScanThreadState* pss = _states[worker_index];
369
370 if (pss == NULL) {
371 continue;
372 }
373
374 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
375 _g1h->policy()->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_index, used_memory, G1GCPhaseTimes::OptCSetUsedMemory);
376 }
377 }
378
379 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
380 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
381
382 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
383 if (forward_ptr == NULL) {
384 // Forward-to-self succeeded. We are the "owner" of the object.
385 HeapRegion* r = _g1h->heap_region_containing(old);
386
387 if (!r->evacuation_failed()) {
388 r->set_evacuation_failed(true);
389 _g1h->hr_printer()->evac_failure(r);
390 }
391
392 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
393
394 G1ScanInYoungSetter x(&_scanner, r->is_young());
395 old->oop_iterate_backwards(&_scanner);
396
397 return old;
398 } else {
399 // Forward-to-self failed. Either someone else managed to allocate
400 // space for this object (old != forward_ptr) or they beat us in
401 // self-forwarding it (old == forward_ptr).
402 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
403 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
404 "should not be in the CSet",
405 p2i(old), p2i(forward_ptr));
406 return forward_ptr;
407 }
408 }
409 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h,
410 uint n_workers,
411 size_t young_cset_length,
412 size_t optional_cset_length) :
413 _g1h(g1h),
414 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
415 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
416 _young_cset_length(young_cset_length),
417 _optional_cset_length(optional_cset_length),
418 _n_workers(n_workers),
419 _flushed(false) {
420 for (uint i = 0; i < n_workers; ++i) {
421 _states[i] = NULL;
422 }
423 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
424 }
425
426 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
427 assert(_flushed, "thread local state from the per thread states should have been flushed");
428 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
429 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
430 }