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 // The dest for Young is used when the objects are aged enough to
79 // need to be moved to the next space.
80 _dest[G1HeapRegionAttr::Young] = G1HeapRegionAttr::Old;
81 _dest[G1HeapRegionAttr::Old] = G1HeapRegionAttr::Old;
82
83 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
84
85 _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions];
86 }
87
88 // Pass locally gathered statistics to global state.
89 void G1ParScanThreadState::flush(size_t* surviving_young_words) {
90 _dcq.flush();
91 // Update allocation statistics.
92 _plab_allocator->flush_and_retire_stats();
93 _g1h->policy()->record_age_table(&_age_table);
94
95 uint length = _g1h->collection_set()->young_region_length();
96 for (uint region_index = 0; region_index < length; region_index++) {
97 surviving_young_words[region_index] += _surviving_young_words[region_index];
98 }
99 }
100
101 G1ParScanThreadState::~G1ParScanThreadState() {
102 delete _plab_allocator;
103 delete _closures;
104 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
105 delete[] _oops_into_optional_regions;
106 }
107
108 size_t G1ParScanThreadState::lab_waste_words() const {
109 return _plab_allocator->waste();
110 }
111
112 size_t G1ParScanThreadState::lab_undo_waste_words() const {
113 return _plab_allocator->undo_waste();
114 }
115
116 #ifdef ASSERT
117 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
118 assert(ref != NULL, "invariant");
119 assert(UseCompressedOops, "sanity");
120 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));
121 oop p = RawAccess<>::oop_load(ref);
122 assert(_g1h->is_in_g1_reserved(p),
123 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
124 return true;
125 }
126
127 bool G1ParScanThreadState::verify_ref(oop* ref) const {
128 assert(ref != NULL, "invariant");
129 if (has_partial_array_mask(ref)) {
130 // Must be in the collection set--it's already been copied.
131 oop p = clear_partial_array_mask(ref);
132 assert(_g1h->is_in_cset(p),
133 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
134 } else {
135 oop p = RawAccess<>::oop_load(ref);
136 assert(_g1h->is_in_g1_reserved(p),
137 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));
138 }
139 return true;
140 }
141
142 bool G1ParScanThreadState::verify_task(StarTask ref) const {
143 if (ref.is_narrow()) {
144 return verify_ref((narrowOop*) ref);
145 } else {
146 return verify_ref((oop*) ref);
147 }
148 }
149 #endif // ASSERT
150
151 void G1ParScanThreadState::trim_queue() {
152 StarTask ref;
153 do {
154 // Fully drain the queue.
155 trim_queue_to_threshold(0);
156 } while (!_refs->is_empty());
157 }
158
159 HeapWord* G1ParScanThreadState::allocate_in_next_plab(G1HeapRegionAttr const region_attr,
160 G1HeapRegionAttr* dest,
161 size_t word_sz,
162 bool previous_plab_refill_failed) {
163 assert(region_attr.is_in_cset_or_humongous(), "Unexpected region attr type: %s", region_attr.get_type_str());
164 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: %s region attr", dest->get_type_str());
165
166 // Right now we only have two types of regions (young / old) so
167 // let's keep the logic here simple. We can generalize it when necessary.
168 if (dest->is_young()) {
169 bool plab_refill_in_old_failed = false;
170 HeapWord* const obj_ptr = _plab_allocator->allocate(G1HeapRegionAttr::Old,
171 word_sz,
172 &plab_refill_in_old_failed);
173 // Make sure that we won't attempt to copy any other objects out
174 // of a survivor region (given that apparently we cannot allocate
175 // any new ones) to avoid coming into this slow path again and again.
176 // Only consider failed PLAB refill here: failed inline allocations are
177 // typically large, so not indicative of remaining space.
178 if (previous_plab_refill_failed) {
179 _tenuring_threshold = 0;
180 }
181
182 if (obj_ptr != NULL) {
183 dest->set_old();
184 } else {
185 // We just failed to allocate in old gen. The same idea as explained above
186 // for making survivor gen unavailable for allocation applies for old gen.
187 _old_gen_is_full = plab_refill_in_old_failed;
188 }
189 return obj_ptr;
190 } else {
191 _old_gen_is_full = previous_plab_refill_failed;
192 assert(dest->is_old(), "Unexpected dest region attr: %s", dest->get_type_str());
193 // no other space to try.
194 return NULL;
195 }
196 }
197
198 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markOop const m, uint& age) {
199 if (region_attr.is_young()) {
200 age = !m->has_displaced_mark_helper() ? m->age()
201 : m->displaced_mark_helper()->age();
202 if (age < _tenuring_threshold) {
203 return region_attr;
204 }
205 }
206 return dest(region_attr);
207 }
208
209 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,
210 oop const old, size_t word_sz, uint age,
211 HeapWord * const obj_ptr) const {
212 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr);
213 if (alloc_buf->contains(obj_ptr)) {
214 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,
215 dest_attr.type() == G1HeapRegionAttr::Old,
216 alloc_buf->word_sz() * HeapWordSize);
217 } else {
218 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,
219 dest_attr.type() == G1HeapRegionAttr::Old);
220 }
221 }
222
223 oop G1ParScanThreadState::copy_to_survivor_space(G1HeapRegionAttr const region_attr,
224 oop const old,
225 markOop const old_mark) {
226 const size_t word_sz = old->size();
227 HeapRegion* const from_region = _g1h->heap_region_containing(old);
228 // +1 to make the -1 indexes valid...
229 const int young_index = from_region->young_index_in_cset()+1;
230 assert( (from_region->is_young() && young_index > 0) ||
231 (!from_region->is_young() && young_index == 0), "invariant" );
232
233 uint age = 0;
234 G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);
235 // The second clause is to prevent premature evacuation failure in case there
236 // is still space in survivor, but old gen is full.
237 if (_old_gen_is_full && dest_attr.is_old()) {
238 return handle_evacuation_failure_par(old, old_mark);
239 }
240 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz);
241
242 // PLAB allocations should succeed most of the time, so we'll
243 // normally check against NULL once and that's it.
244 if (obj_ptr == NULL) {
245 bool plab_refill_failed = false;
246 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_attr, word_sz, &plab_refill_failed);
247 if (obj_ptr == NULL) {
248 obj_ptr = allocate_in_next_plab(region_attr, &dest_attr, word_sz, plab_refill_failed);
249 if (obj_ptr == NULL) {
250 // This will either forward-to-self, or detect that someone else has
251 // installed a forwarding pointer.
252 return handle_evacuation_failure_par(old, old_mark);
253 }
254 }
255 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {
256 // The events are checked individually as part of the actual commit
257 report_promotion_event(dest_attr, old, word_sz, age, obj_ptr);
258 }
259 }
260
261 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
262 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
263
264 #ifndef PRODUCT
265 // Should this evacuation fail?
266 if (_g1h->evacuation_should_fail()) {
267 // Doing this after all the allocation attempts also tests the
268 // undo_allocation() method too.
269 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz);
270 return handle_evacuation_failure_par(old, old_mark);
271 }
272 #endif // !PRODUCT
273
274 // We're going to allocate linearly, so might as well prefetch ahead.
275 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
276
277 const oop obj = oop(obj_ptr);
278 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed);
279 if (forward_ptr == NULL) {
280 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
281
282 if (dest_attr.is_young()) {
283 if (age < markOopDesc::max_age) {
284 age++;
285 }
286 if (old_mark->has_displaced_mark_helper()) {
287 // In this case, we have to install the mark word first,
288 // otherwise obj looks to be forwarded (the old mark word,
289 // which contains the forward pointer, was copied)
290 obj->set_mark_raw(old_mark);
291 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
292 old_mark->set_displaced_mark_helper(new_mark);
293 } else {
294 obj->set_mark_raw(old_mark->set_age(age));
295 }
296 _age_table.add(age, word_sz);
297 } else {
298 obj->set_mark_raw(old_mark);
299 }
300
301 if (G1StringDedup::is_enabled()) {
302 const bool is_from_young = region_attr.is_young();
303 const bool is_to_young = dest_attr.is_young();
304 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(),
305 "sanity");
306 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),
307 "sanity");
308 G1StringDedup::enqueue_from_evacuation(is_from_young,
309 is_to_young,
310 _worker_id,
311 obj);
312 }
313
314 _surviving_young_words[young_index] += word_sz;
315
316 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
317 // We keep track of the next start index in the length field of
318 // the to-space object. The actual length can be found in the
319 // length field of the from-space object.
320 arrayOop(obj)->set_length(0);
321 oop* old_p = set_partial_array_mask(old);
322 do_oop_partial_array(old_p);
323 } else {
324 G1ScanInYoungSetter x(&_scanner, dest_attr.is_young());
325 obj->oop_iterate_backwards(&_scanner);
326 }
327 return obj;
328 } else {
329 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz);
330 return forward_ptr;
331 }
332 }
333
334 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {
335 assert(worker_id < _n_workers, "out of bounds access");
336 if (_states[worker_id] == NULL) {
337 _states[worker_id] =
338 new G1ParScanThreadState(_g1h, worker_id, _young_cset_length, _optional_cset_length);
339 }
340 return _states[worker_id];
341 }
342
343 const size_t* G1ParScanThreadStateSet::surviving_young_words() const {
344 assert(_flushed, "thread local state from the per thread states should have been flushed");
345 return _surviving_young_words_total;
346 }
347
348 void G1ParScanThreadStateSet::flush() {
349 assert(!_flushed, "thread local state from the per thread states should be flushed once");
350
351 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
352 G1ParScanThreadState* pss = _states[worker_index];
353
354 if (pss == NULL) {
355 continue;
356 }
357
358 pss->flush(_surviving_young_words_total);
359 delete pss;
360 _states[worker_index] = NULL;
361 }
362 _flushed = true;
363 }
364
365 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {
366 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {
367 G1ParScanThreadState* pss = _states[worker_index];
368
369 if (pss == NULL) {
370 continue;
371 }
372
373 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();
374 _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_index, used_memory, G1GCPhaseTimes::ScanRSUsedMemory);
375 }
376 }
377
378 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
379 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));
380
381 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);
382 if (forward_ptr == NULL) {
383 // Forward-to-self succeeded. We are the "owner" of the object.
384 HeapRegion* r = _g1h->heap_region_containing(old);
385
386 if (!r->evacuation_failed()) {
387 r->set_evacuation_failed(true);
388 _g1h->hr_printer()->evac_failure(r);
389 }
390
391 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);
392
393 G1ScanInYoungSetter x(&_scanner, r->is_young());
394 old->oop_iterate_backwards(&_scanner);
395
396 return old;
397 } else {
398 // Forward-to-self failed. Either someone else managed to allocate
399 // space for this object (old != forward_ptr) or they beat us in
400 // self-forwarding it (old == forward_ptr).
401 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),
402 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
403 "should not be in the CSet",
404 p2i(old), p2i(forward_ptr));
405 return forward_ptr;
406 }
407 }
408 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h,
409 uint n_workers,
410 size_t young_cset_length,
411 size_t optional_cset_length) :
412 _g1h(g1h),
413 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),
414 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)),
415 _young_cset_length(young_cset_length),
416 _optional_cset_length(optional_cset_length),
417 _n_workers(n_workers),
418 _flushed(false) {
419 for (uint i = 0; i < n_workers; ++i) {
420 _states[i] = NULL;
421 }
422 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t));
423 }
424
425 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {
426 assert(_flushed, "thread local state from the per thread states should have been flushed");
427 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);
428 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);
429 }