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/oop.inline.hpp"
37 #include "runtime/prefetch.inline.hpp"
38
39 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length)
40 : _g1h(g1h),
41 _refs(g1h->task_queue(worker_id)),
42 _dcq(&g1h->dirty_card_queue_set()),
43 _ct(g1h->card_table()),
44 _closures(NULL),
45 _hash_seed(17),
46 _worker_id(worker_id),
47 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),
48 _age_table(false),
49 _scanner(g1h, this),
50 _old_gen_is_full(false)
51 {
52 // we allocate G1YoungSurvRateNumRegions plus one entries, since
53 // we "sacrifice" entry 0 to keep track of surviving bytes for
54 // non-young regions (where the age is -1)
55 // We also add a few elements at the beginning and at the end in
56 // an attempt to eliminate cache contention
57 size_t real_length = 1 + young_cset_length;
58 size_t array_length = PADDING_ELEM_NUM +
59 real_length +
60 PADDING_ELEM_NUM;
61 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
62 if (_surviving_young_words_base == NULL)
63 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
64 "Not enough space for young surv histo.");
65 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
66 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
67
68 _plab_allocator = new G1DefaultPLABAllocator(_g1h->allocator());
69
70 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
71 // The dest for Young is used when the objects are aged enough to
72 // need to be moved to the next space.
73 _dest[InCSetState::Young] = InCSetState::Old;
74 _dest[InCSetState::Old] = InCSetState::Old;
75
76 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
77 }
78
79 // Pass locally gathered statistics to global state.
80 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
81 _dcq.flush();
82 // Update allocation statistics.
83 _plab_allocator->flush_and_retire_stats();
84 _g1h->g1_policy()->record_age_table(&_age_table);
85
86 uint length = _g1h->collection_set()->young_region_length();
87 for (uint region_index = 0; region_index < length; region_index++) {
88 surviving_young_words[region_index] += _surviving_young_words[region_index];
89 }
90 }
91
92 G1ParScanThreadState::~G1ParScanThreadState() {
93 delete _plab_allocator;
94 delete _closures;
95 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
96 }
97
98 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) {
99 _plab_allocator->waste(wasted, undo_wasted);
100 }
101
102 #ifdef ASSERT
103 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
104 assert(ref != NULL, "invariant");
105 assert(UseCompressedOops, "sanity");
106 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
107 oop p = oopDesc::load_decode_heap_oop(ref);
108 assert(_g1h->is_in_g1_reserved(p),
109 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
110 return true;
111 }
112
113 bool G1ParScanThreadState::verify_ref(oop* ref) const {
114 assert(ref != NULL, "invariant");
115 if (has_partial_array_mask(ref)) {
116 // Must be in the collection set--it's already been copied.
117 oop p = clear_partial_array_mask(ref);
118 assert(_g1h->is_in_cset(p),
119 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
120 } else {
121 oop p = oopDesc::load_decode_heap_oop(ref);
122 assert(_g1h->is_in_g1_reserved(p),
123 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
124 }
125 return true;
126 }
127
128 bool G1ParScanThreadState::verify_task(StarTask ref) const {
129 if (ref.is_narrow()) {
130 return verify_ref((narrowOop*) ref);
131 } else {
132 return verify_ref((oop*) ref);
133 }
134 }
135 #endif // ASSERT
136
137 void G1ParScanThreadState::trim_queue() {
138 StarTask ref;
139 do {
140 // Drain the overflow stack first, so other threads can steal.
141 while (_refs->pop_overflow(ref)) {
142 if (!_refs->try_push_to_taskqueue(ref)) {
143 dispatch_reference(ref);
144 }
145 }
146
147 while (_refs->pop_local(ref)) {
148 dispatch_reference(ref);
149 }
150 } while (!_refs->is_empty());
151 }
152
153 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
154 InCSetState* dest,
155 size_t word_sz,
156 bool previous_plab_refill_failed) {
157 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());
158 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
159
160 // Right now we only have two types of regions (young / old) so
161 // let's keep the logic here simple. We can generalize it when necessary.
162 if (dest->is_young()) {
163 bool plab_refill_in_old_failed = false;
164 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old,
165 word_sz,
166 &plab_refill_in_old_failed);
167 // Make sure that we won't attempt to copy any other objects out
168 // of a survivor region (given that apparently we cannot allocate
169 // any new ones) to avoid coming into this slow path again and again.
170 // Only consider failed PLAB refill here: failed inline allocations are
171 // typically large, so not indicative of remaining space.
172 if (previous_plab_refill_failed) {
173 _tenuring_threshold = 0;
174 }
175
176 if (obj_ptr != NULL) {
177 dest->set_old();
178 } else {
179 // We just failed to allocate in old gen. The same idea as explained above
180 // for making survivor gen unavailable for allocation applies for old gen.
181 _old_gen_is_full = plab_refill_in_old_failed;
182 }
183 return obj_ptr;
184 } else {
185 _old_gen_is_full = previous_plab_refill_failed;
186 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());
187 // no other space to try.
188 return NULL;
189 }
190 }
191
192 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
193 if (state.is_young()) {
194 age = !m->has_displaced_mark_helper() ? m->age()
195 : m->displaced_mark_helper()->age();
196 if (age < _tenuring_threshold) {
197 return state;
198 }
199 }
200 return dest(state);
201 }
202
203 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,
204 oop const old, size_t word_sz, uint age,
205 HeapWord * const obj_ptr) const {
206 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state);
207 if (alloc_buf->contains(obj_ptr)) {
208 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age,
209 dest_state.value() == InCSetState::Old,
210 alloc_buf->word_sz());
211 } else {
212 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age,
213 dest_state.value() == InCSetState::Old);
214 }
215 }
216
217 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
218 oop const old,
219 markOop const old_mark) {
220 const size_t word_sz = old->size();
221 HeapRegion* const from_region = _g1h->heap_region_containing(old);
222 // +1 to make the -1 indexes valid...
223 const int young_index = from_region->young_index_in_cset()+1;
224 assert( (from_region->is_young() && young_index > 0) ||
225 (!from_region->is_young() && young_index == 0), "invariant" );
226
227 uint age = 0;
228 InCSetState dest_state = next_state(state, old_mark, age);
229 // The second clause is to prevent premature evacuation failure in case there
230 // is still space in survivor, but old gen is full.
231 if (_old_gen_is_full && dest_state.is_old()) {
232 return handle_evacuation_failure_par(old, old_mark);
233 }
234 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz);
235
236 // PLAB allocations should succeed most of the time, so we'll
237 // normally check against NULL once and that's it.
238 if (obj_ptr == NULL) {
239 bool plab_refill_failed = false;
240 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed);
241 if (obj_ptr == NULL) {
242 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed);
243 if (obj_ptr == NULL) {
244 // This will either forward-to-self, or detect that someone else has
245 // installed a forwarding pointer.
246 return handle_evacuation_failure_par(old, old_mark);
247 }
248 }
249 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
250 // The events are checked individually as part of the actual commit
251 report_promotion_event(dest_state, old, word_sz, age, obj_ptr);
252 }
253 }
254
255 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
256 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
257
258 #ifndef PRODUCT
259 // Should this evacuation fail?
260 if (_g1h->evacuation_should_fail()) {
261 // Doing this after all the allocation attempts also tests the
262 // undo_allocation() method too.
263 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
264 return handle_evacuation_failure_par(old, old_mark);
265 }
266 #endif // !PRODUCT
267
268 // We're going to allocate linearly, so might as well prefetch ahead.
269 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
270
271 const oop obj = oop(obj_ptr);
272 const oop forward_ptr = old->forward_to_atomic(obj);
273 if (forward_ptr == NULL) {
274 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
275
276 if (dest_state.is_young()) {
277 if (age < markOopDesc::max_age) {
278 age++;
279 }
280 if (old_mark->has_displaced_mark_helper()) {
281 // In this case, we have to install the mark word first,
282 // otherwise obj looks to be forwarded (the old mark word,
283 // which contains the forward pointer, was copied)
284 obj->set_mark_raw(old_mark);
285 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
286 old_mark->set_displaced_mark_helper(new_mark);
287 } else {
288 obj->set_mark_raw(old_mark->set_age(age));
289 }
290 _age_table.add(age, word_sz);
291 } else {
292 obj->set_mark_raw(old_mark);
293 }
294
295 if (G1StringDedup::is_enabled()) {
296 const bool is_from_young = state.is_young();
297 const bool is_to_young = dest_state.is_young();
298 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
299 "sanity");
300 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
301 "sanity");
302 G1StringDedup::enqueue_from_evacuation(is_from_young,
303 is_to_young,
304 _worker_id,
305 obj);
306 }
307
308 _surviving_young_words[young_index] += word_sz;
309
310 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
311 // We keep track of the next start index in the length field of
312 // the to-space object. The actual length can be found in the
313 // length field of the from-space object.
314 arrayOop(obj)->set_length(0);
315 oop* old_p = set_partial_array_mask(old);
316 push_on_queue(old_p);
317 } else {
318 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr);
319 _scanner.set_region(to_region);
320 obj->oop_iterate_backwards(&_scanner);
321 }
322 return obj;
323 } else {
324 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz);
325 return forward_ptr;
326 }
327 }
328
329 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
330 assert(worker_id < _n_workers, "out of bounds access");
331 if (_states[worker_id] == NULL) {
332 _states[worker_id] = new G1ParScanThreadState(_g1h, worker_id, _young_cset_length);
333 }
334 return _states[worker_id];
335 }
336
337 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
338 assert(_flushed, "thread local state from the per thread states should have been flushed");
339 return _surviving_young_words_total;
340 }
341
342 void G1ParScanThreadStateSet::flush() {
343 assert(!_flushed, "thread local state from the per thread states should be flushed once");
344
345 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
346 G1ParScanThreadState* pss = _states[worker_index];
347
348 if (pss == NULL) {
349 continue;
350 }
351
352 pss->flush(_surviving_young_words_total);
353 delete pss;
354 _states[worker_index] = NULL;
355 }
356 _flushed = true;
357 }
358
359 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
360 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
361
362 oop forward_ptr = old->forward_to_atomic(old);
363 if (forward_ptr == NULL) {
364 // Forward-to-self succeeded. We are the "owner" of the object.
365 HeapRegion* r = _g1h->heap_region_containing(old);
366
367 if (!r->evacuation_failed()) {
368 r->set_evacuation_failed(true);
369 _g1h->hr_printer()->evac_failure(r);
370 }
371
372 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
373
374 _scanner.set_region(r);
375 old->oop_iterate_backwards(&_scanner);
376
377 return old;
378 } else {
379 // Forward-to-self failed. Either someone else managed to allocate
380 // space for this object (old != forward_ptr) or they beat us in
381 // self-forwarding it (old == forward_ptr).
382 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
383 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
384 "should not be in the CSet",
385 p2i(old), p2i(forward_ptr));
386 return forward_ptr;
387 }
388 }
389 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) :
390 _g1h(g1h),
391 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
392 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
393 _young_cset_length(young_cset_length),
394 _n_workers(n_workers),
395 _flushed(false) {
396 for (uint i = 0; i < n_workers; ++i) {
397 _states[i] = NULL;
398 }
399 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
400 }
401
402 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
403 assert(_flushed, "thread local state from the per thread states should have been flushed");
404 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
405 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
406 }