1 /*
2 * Copyright (c) 2014, 2018, 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->g1_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_C_HEAP_ARRAY(G1OopStarChunkedList, _num_optional_regions, mtGC);
87 for (size_t i = 0; i < _num_optional_regions; i++) {
88 ::new (_oops_into_optional_regions + i) G1OopStarChunkedList();
89 }
90 }
91
92 // Pass locally gathered statistics to global state.
93 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
94 _dcq.flush();
95 // Update allocation statistics.
96 _plab_allocator->flush_and_retire_stats();
97 _g1h->g1_policy()->record_age_table(&_age_table);
98
99 uint length = _g1h->collection_set()->young_region_length();
100 for (uint region_index = 0; region_index < length; region_index++) {
101 surviving_young_words[region_index] += _surviving_young_words[region_index];
102 }
103 }
104
105 G1ParScanThreadState::~G1ParScanThreadState() {
106 delete _plab_allocator;
107 delete _closures;
108 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
109 size_t used_by_optional = 0;
110 for (size_t i = 0; i < _num_optional_regions; i++) {
111 used_by_optional += _oops_into_optional_regions[i].free_chunk_lists();
112 }
113 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::OptScanRS, _worker_id, used_by_optional, G1GCPhaseTimes::OptCSetUsedMemory);
114 FREE_C_HEAP_ARRAY(G1OopStarChunkedList, _oops_into_optional_regions);
115 }
116
117 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) {
118 _plab_allocator->waste(wasted, undo_wasted);
119 }
120
121 #ifdef ASSERT
122 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
123 assert(ref != NULL, "invariant");
124 assert(UseCompressedOops, "sanity");
125 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
126 oop p = RawAccess<>::oop_load(ref);
127 assert(_g1h->is_in_g1_reserved(p),
128 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
129 return true;
130 }
131
132 bool G1ParScanThreadState::verify_ref(oop* ref) const {
133 assert(ref != NULL, "invariant");
134 if (has_partial_array_mask(ref)) {
135 // Must be in the collection set--it's already been copied.
136 oop p = clear_partial_array_mask(ref);
137 assert(_g1h->is_in_cset(p),
138 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
139 } else {
140 oop p = RawAccess<>::oop_load(ref);
141 assert(_g1h->is_in_g1_reserved(p),
142 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
143 }
144 return true;
145 }
146
147 bool G1ParScanThreadState::verify_task(StarTask ref) const {
148 if (ref.is_narrow()) {
149 return verify_ref((narrowOop*) ref);
150 } else {
151 return verify_ref((oop*) ref);
152 }
153 }
154 #endif // ASSERT
155
156 void G1ParScanThreadState::trim_queue() {
157 StarTask ref;
158 do {
159 // Fully drain the queue.
160 trim_queue_to_threshold(0);
161 } while (!_refs->is_empty());
162 }
163
164 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
165 InCSetState* dest,
166 size_t word_sz,
167 bool previous_plab_refill_failed) {
168 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());
169 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
170
171 // Right now we only have two types of regions (young / old) so
172 // let's keep the logic here simple. We can generalize it when necessary.
173 if (dest->is_young()) {
174 bool plab_refill_in_old_failed = false;
175 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old,
176 word_sz,
177 &plab_refill_in_old_failed);
178 // Make sure that we won't attempt to copy any other objects out
179 // of a survivor region (given that apparently we cannot allocate
180 // any new ones) to avoid coming into this slow path again and again.
181 // Only consider failed PLAB refill here: failed inline allocations are
182 // typically large, so not indicative of remaining space.
183 if (previous_plab_refill_failed) {
184 _tenuring_threshold = 0;
185 }
186
187 if (obj_ptr != NULL) {
188 dest->set_old();
189 } else {
190 // We just failed to allocate in old gen. The same idea as explained above
191 // for making survivor gen unavailable for allocation applies for old gen.
192 _old_gen_is_full = plab_refill_in_old_failed;
193 }
194 return obj_ptr;
195 } else {
196 _old_gen_is_full = previous_plab_refill_failed;
197 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
198 // no other space to try.
199 return NULL;
200 }
201 }
202
203 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
204 if (state.is_young()) {
205 age = !m->has_displaced_mark_helper() ? m->age()
206 : m->displaced_mark_helper()->age();
207 if (age < _tenuring_threshold) {
208 return state;
209 }
210 }
211 return dest(state);
212 }
213
214 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,
215 oop const old, size_t word_sz, uint age,
216 HeapWord * const obj_ptr) const {
217 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state);
218 if (alloc_buf->contains(obj_ptr)) {
219 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
220 dest_state.value() == InCSetState::Old,
221 alloc_buf->word_sz() * HeapWordSize);
222 } else {
223 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
224 dest_state.value() == InCSetState::Old);
225 }
226 }
227
228 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
229 oop const old,
230 markOop const old_mark) {
231 const size_t word_sz = old->size();
232 HeapRegion* const from_region = _g1h->heap_region_containing(old);
233 // +1 to make the -1 indexes valid...
234 const int young_index = from_region->young_index_in_cset()+1;
235 assert( (from_region->is_young() && young_index > 0) ||
236 (!from_region->is_young() && young_index == 0), "invariant" );
237
238 uint age = 0;
239 InCSetState dest_state = next_state(state, old_mark, age);
240 // The second clause is to prevent premature evacuation failure in case there
241 // is still space in survivor, but old gen is full.
242 if (_old_gen_is_full && dest_state.is_old()) {
243 return handle_evacuation_failure_par(old, old_mark);
244 }
245 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz);
246
247 // PLAB allocations should succeed most of the time, so we'll
248 // normally check against NULL once and that's it.
249 if (obj_ptr == NULL) {
250 bool plab_refill_failed = false;
251 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed);
252 if (obj_ptr == NULL) {
253 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed);
254 if (obj_ptr == NULL) {
255 // This will either forward-to-self, or detect that someone else has
256 // installed a forwarding pointer.
257 return handle_evacuation_failure_par(old, old_mark);
258 }
259 }
260 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
261 // The events are checked individually as part of the actual commit
262 report_promotion_event(dest_state, old, word_sz, age, obj_ptr);
263 }
264 }
265
266 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
267 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
268
269 #ifndef PRODUCT
270 // Should this evacuation fail?
271 if (_g1h->evacuation_should_fail()) {
272 // Doing this after all the allocation attempts also tests the
273 // undo_allocation() method too.
274 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
275 return handle_evacuation_failure_par(old, old_mark);
276 }
277 #endif // !PRODUCT
278
279 // We're going to allocate linearly, so might as well prefetch ahead.
280 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
281
282 const oop obj = oop(obj_ptr);
283 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed);
284 if (forward_ptr == NULL) {
285 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
286
287 if (dest_state.is_young()) {
288 if (age < markOopDesc::max_age) {
289 age++;
290 }
291 if (old_mark->has_displaced_mark_helper()) {
292 // In this case, we have to install the mark word first,
293 // otherwise obj looks to be forwarded (the old mark word,
294 // which contains the forward pointer, was copied)
295 obj->set_mark_raw(old_mark);
296 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
297 old_mark->set_displaced_mark_helper(new_mark);
298 } else {
299 obj->set_mark_raw(old_mark->set_age(age));
300 }
301 _age_table.add(age, word_sz);
302 } else {
303 obj->set_mark_raw(old_mark);
304 }
305
306 if (G1StringDedup::is_enabled()) {
307 const bool is_from_young = state.is_young();
308 const bool is_to_young = dest_state.is_young();
309 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
310 "sanity");
311 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
312 "sanity");
313 G1StringDedup::enqueue_from_evacuation(is_from_young,
314 is_to_young,
315 _worker_id,
316 obj);
317 }
318
319 _surviving_young_words[young_index] += word_sz;
320
321 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
322 // We keep track of the next start index in the length field of
323 // the to-space object. The actual length can be found in the
324 // length field of the from-space object.
325 arrayOop(obj)->set_length(0);
326 oop* old_p = set_partial_array_mask(old);
327 do_oop_partial_array(old_p);
328 } else {
329 G1ScanInYoungSetter x(&_scanner, dest_state.is_young());
330 obj->oop_iterate_backwards(&_scanner);
331 }
332 return obj;
333 } else {
334 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
335 return forward_ptr;
336 }
337 }
338
339 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
340 assert(worker_id < _n_workers, "out of bounds access");
341 if (_states[worker_id] == NULL) {
342 _states[worker_id] =
343 new G1ParScanThreadState(_g1h, worker_id, _young_cset_length, _optional_cset_length);
344 }
345 return _states[worker_id];
346 }
347
348 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
349 assert(_flushed, "thread local state from the per thread states should have been flushed");
350 return _surviving_young_words_total;
351 }
352
353 void G1ParScanThreadStateSet::flush() {
354 assert(!_flushed, "thread local state from the per thread states should be flushed once");
355
356 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
357 G1ParScanThreadState* pss = _states[worker_index];
358
359 if (pss == NULL) {
360 continue;
361 }
362
363 pss->flush(_surviving_young_words_total);
364 delete pss;
365 _states[worker_index] = NULL;
366 }
367 _flushed = true;
368 }
369
370 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
371 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
372
373 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
374 if (forward_ptr == NULL) {
375 // Forward-to-self succeeded. We are the "owner" of the object.
376 HeapRegion* r = _g1h->heap_region_containing(old);
377
378 if (!r->evacuation_failed()) {
379 r->set_evacuation_failed(true);
380 _g1h->hr_printer()->evac_failure(r);
381 }
382
383 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
384
385 G1ScanInYoungSetter x(&_scanner, r->is_young());
386 old->oop_iterate_backwards(&_scanner);
387
388 return old;
389 } else {
390 // Forward-to-self failed. Either someone else managed to allocate
391 // space for this object (old != forward_ptr) or they beat us in
392 // self-forwarding it (old == forward_ptr).
393 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
394 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
395 "should not be in the CSet",
396 p2i(old), p2i(forward_ptr));
397 return forward_ptr;
398 }
399 }
400 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h,
401 uint n_workers,
402 size_t young_cset_length,
403 size_t optional_cset_length) :
404 _g1h(g1h),
405 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
406 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
407 _young_cset_length(young_cset_length),
408 _optional_cset_length(optional_cset_length),
409 _n_workers(n_workers),
410 _flushed(false) {
411 for (uint i = 0; i < n_workers; ++i) {
412 _states[i] = NULL;
413 }
414 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
415 }
416
417 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
418 assert(_flushed, "thread local state from the per thread states should have been flushed");
419 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
420 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
421 }