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--- old/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
+++ new/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
1 1 /*
2 2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 4 *
5 5 * This code is free software; you can redistribute it and/or modify it
6 6 * under the terms of the GNU General Public License version 2 only, as
7 7 * published by the Free Software Foundation.
8 8 *
9 9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 12 * version 2 for more details (a copy is included in the LICENSE file that
13 13 * accompanied this code).
14 14 *
15 15 * You should have received a copy of the GNU General Public License version
16 16 * 2 along with this work; if not, write to the Free Software Foundation,
17 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 18 *
19 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 20 * or visit www.oracle.com if you need additional information or have any
21 21 * questions.
22 22 *
23 23 */
24 24
25 25 #include "precompiled.hpp"
26 26 #include "code/icBuffer.hpp"
27 27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 31 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
32 32 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
33 33 #include "gc_implementation/g1/g1MarkSweep.hpp"
34 34 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
35 35 #include "gc_implementation/g1/g1RemSet.inline.hpp"
36 36 #include "gc_implementation/g1/heapRegionRemSet.hpp"
37 37 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
38 38 #include "gc_implementation/g1/vm_operations_g1.hpp"
39 39 #include "gc_implementation/shared/isGCActiveMark.hpp"
40 40 #include "memory/gcLocker.inline.hpp"
41 41 #include "memory/genOopClosures.inline.hpp"
42 42 #include "memory/generationSpec.hpp"
43 43 #include "oops/oop.inline.hpp"
44 44 #include "oops/oop.pcgc.inline.hpp"
45 45 #include "runtime/aprofiler.hpp"
46 46 #include "runtime/vmThread.hpp"
47 47
48 48 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
49 49
50 50 // turn it on so that the contents of the young list (scan-only /
51 51 // to-be-collected) are printed at "strategic" points before / during
52 52 // / after the collection --- this is useful for debugging
53 53 #define YOUNG_LIST_VERBOSE 0
54 54 // CURRENT STATUS
55 55 // This file is under construction. Search for "FIXME".
56 56
57 57 // INVARIANTS/NOTES
58 58 //
59 59 // All allocation activity covered by the G1CollectedHeap interface is
60 60 // serialized by acquiring the HeapLock. This happens in mem_allocate
61 61 // and allocate_new_tlab, which are the "entry" points to the
62 62 // allocation code from the rest of the JVM. (Note that this does not
63 63 // apply to TLAB allocation, which is not part of this interface: it
64 64 // is done by clients of this interface.)
65 65
66 66 // Local to this file.
67 67
68 68 class RefineCardTableEntryClosure: public CardTableEntryClosure {
69 69 SuspendibleThreadSet* _sts;
70 70 G1RemSet* _g1rs;
71 71 ConcurrentG1Refine* _cg1r;
72 72 bool _concurrent;
73 73 public:
74 74 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
75 75 G1RemSet* g1rs,
76 76 ConcurrentG1Refine* cg1r) :
77 77 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
78 78 {}
79 79 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
80 80 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
81 81 // This path is executed by the concurrent refine or mutator threads,
82 82 // concurrently, and so we do not care if card_ptr contains references
83 83 // that point into the collection set.
84 84 assert(!oops_into_cset, "should be");
85 85
86 86 if (_concurrent && _sts->should_yield()) {
87 87 // Caller will actually yield.
88 88 return false;
89 89 }
90 90 // Otherwise, we finished successfully; return true.
91 91 return true;
92 92 }
93 93 void set_concurrent(bool b) { _concurrent = b; }
94 94 };
95 95
96 96
97 97 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
98 98 int _calls;
99 99 G1CollectedHeap* _g1h;
100 100 CardTableModRefBS* _ctbs;
101 101 int _histo[256];
102 102 public:
103 103 ClearLoggedCardTableEntryClosure() :
104 104 _calls(0)
105 105 {
106 106 _g1h = G1CollectedHeap::heap();
107 107 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
108 108 for (int i = 0; i < 256; i++) _histo[i] = 0;
109 109 }
110 110 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
111 111 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
112 112 _calls++;
113 113 unsigned char* ujb = (unsigned char*)card_ptr;
114 114 int ind = (int)(*ujb);
115 115 _histo[ind]++;
116 116 *card_ptr = -1;
117 117 }
118 118 return true;
119 119 }
120 120 int calls() { return _calls; }
121 121 void print_histo() {
122 122 gclog_or_tty->print_cr("Card table value histogram:");
123 123 for (int i = 0; i < 256; i++) {
124 124 if (_histo[i] != 0) {
125 125 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
126 126 }
127 127 }
128 128 }
129 129 };
130 130
131 131 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
132 132 int _calls;
133 133 G1CollectedHeap* _g1h;
134 134 CardTableModRefBS* _ctbs;
135 135 public:
136 136 RedirtyLoggedCardTableEntryClosure() :
137 137 _calls(0)
138 138 {
139 139 _g1h = G1CollectedHeap::heap();
140 140 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
141 141 }
142 142 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
143 143 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
144 144 _calls++;
145 145 *card_ptr = 0;
146 146 }
147 147 return true;
148 148 }
149 149 int calls() { return _calls; }
150 150 };
151 151
152 152 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
153 153 public:
154 154 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
155 155 *card_ptr = CardTableModRefBS::dirty_card_val();
156 156 return true;
157 157 }
158 158 };
159 159
160 160 YoungList::YoungList(G1CollectedHeap* g1h)
161 161 : _g1h(g1h), _head(NULL),
162 162 _length(0),
163 163 _last_sampled_rs_lengths(0),
164 164 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
165 165 {
166 166 guarantee( check_list_empty(false), "just making sure..." );
167 167 }
168 168
169 169 void YoungList::push_region(HeapRegion *hr) {
170 170 assert(!hr->is_young(), "should not already be young");
171 171 assert(hr->get_next_young_region() == NULL, "cause it should!");
172 172
173 173 hr->set_next_young_region(_head);
174 174 _head = hr;
175 175
176 176 hr->set_young();
177 177 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
178 178 ++_length;
179 179 }
180 180
181 181 void YoungList::add_survivor_region(HeapRegion* hr) {
182 182 assert(hr->is_survivor(), "should be flagged as survivor region");
183 183 assert(hr->get_next_young_region() == NULL, "cause it should!");
184 184
185 185 hr->set_next_young_region(_survivor_head);
186 186 if (_survivor_head == NULL) {
187 187 _survivor_tail = hr;
188 188 }
189 189 _survivor_head = hr;
190 190
191 191 ++_survivor_length;
192 192 }
193 193
194 194 void YoungList::empty_list(HeapRegion* list) {
195 195 while (list != NULL) {
196 196 HeapRegion* next = list->get_next_young_region();
197 197 list->set_next_young_region(NULL);
198 198 list->uninstall_surv_rate_group();
199 199 list->set_not_young();
200 200 list = next;
201 201 }
202 202 }
203 203
204 204 void YoungList::empty_list() {
205 205 assert(check_list_well_formed(), "young list should be well formed");
206 206
207 207 empty_list(_head);
208 208 _head = NULL;
209 209 _length = 0;
210 210
211 211 empty_list(_survivor_head);
212 212 _survivor_head = NULL;
213 213 _survivor_tail = NULL;
214 214 _survivor_length = 0;
215 215
216 216 _last_sampled_rs_lengths = 0;
217 217
218 218 assert(check_list_empty(false), "just making sure...");
219 219 }
220 220
221 221 bool YoungList::check_list_well_formed() {
222 222 bool ret = true;
223 223
224 224 size_t length = 0;
225 225 HeapRegion* curr = _head;
226 226 HeapRegion* last = NULL;
227 227 while (curr != NULL) {
228 228 if (!curr->is_young()) {
229 229 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
230 230 "incorrectly tagged (y: %d, surv: %d)",
231 231 curr->bottom(), curr->end(),
232 232 curr->is_young(), curr->is_survivor());
233 233 ret = false;
234 234 }
235 235 ++length;
236 236 last = curr;
237 237 curr = curr->get_next_young_region();
238 238 }
239 239 ret = ret && (length == _length);
240 240
241 241 if (!ret) {
242 242 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
243 243 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
244 244 length, _length);
245 245 }
246 246
247 247 return ret;
248 248 }
249 249
250 250 bool YoungList::check_list_empty(bool check_sample) {
251 251 bool ret = true;
252 252
253 253 if (_length != 0) {
254 254 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
255 255 _length);
256 256 ret = false;
257 257 }
258 258 if (check_sample && _last_sampled_rs_lengths != 0) {
259 259 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
260 260 ret = false;
261 261 }
262 262 if (_head != NULL) {
263 263 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
264 264 ret = false;
265 265 }
266 266 if (!ret) {
267 267 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
268 268 }
269 269
270 270 return ret;
271 271 }
272 272
273 273 void
274 274 YoungList::rs_length_sampling_init() {
275 275 _sampled_rs_lengths = 0;
276 276 _curr = _head;
277 277 }
278 278
279 279 bool
280 280 YoungList::rs_length_sampling_more() {
281 281 return _curr != NULL;
282 282 }
283 283
284 284 void
285 285 YoungList::rs_length_sampling_next() {
286 286 assert( _curr != NULL, "invariant" );
287 287 size_t rs_length = _curr->rem_set()->occupied();
288 288
289 289 _sampled_rs_lengths += rs_length;
290 290
291 291 // The current region may not yet have been added to the
292 292 // incremental collection set (it gets added when it is
293 293 // retired as the current allocation region).
294 294 if (_curr->in_collection_set()) {
295 295 // Update the collection set policy information for this region
296 296 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
297 297 }
298 298
299 299 _curr = _curr->get_next_young_region();
300 300 if (_curr == NULL) {
301 301 _last_sampled_rs_lengths = _sampled_rs_lengths;
302 302 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
303 303 }
304 304 }
305 305
306 306 void
307 307 YoungList::reset_auxilary_lists() {
308 308 guarantee( is_empty(), "young list should be empty" );
309 309 assert(check_list_well_formed(), "young list should be well formed");
310 310
311 311 // Add survivor regions to SurvRateGroup.
312 312 _g1h->g1_policy()->note_start_adding_survivor_regions();
313 313 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
314 314
315 315 for (HeapRegion* curr = _survivor_head;
316 316 curr != NULL;
317 317 curr = curr->get_next_young_region()) {
318 318 _g1h->g1_policy()->set_region_survivors(curr);
319 319
320 320 // The region is a non-empty survivor so let's add it to
321 321 // the incremental collection set for the next evacuation
322 322 // pause.
323 323 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
324 324 }
325 325 _g1h->g1_policy()->note_stop_adding_survivor_regions();
326 326
327 327 _head = _survivor_head;
328 328 _length = _survivor_length;
329 329 if (_survivor_head != NULL) {
330 330 assert(_survivor_tail != NULL, "cause it shouldn't be");
331 331 assert(_survivor_length > 0, "invariant");
332 332 _survivor_tail->set_next_young_region(NULL);
333 333 }
334 334
335 335 // Don't clear the survivor list handles until the start of
336 336 // the next evacuation pause - we need it in order to re-tag
337 337 // the survivor regions from this evacuation pause as 'young'
338 338 // at the start of the next.
339 339
340 340 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
341 341
342 342 assert(check_list_well_formed(), "young list should be well formed");
343 343 }
344 344
345 345 void YoungList::print() {
346 346 HeapRegion* lists[] = {_head, _survivor_head};
347 347 const char* names[] = {"YOUNG", "SURVIVOR"};
348 348
349 349 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
350 350 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
351 351 HeapRegion *curr = lists[list];
352 352 if (curr == NULL)
353 353 gclog_or_tty->print_cr(" empty");
354 354 while (curr != NULL) {
355 355 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
356 356 "age: %4d, y: %d, surv: %d",
357 357 curr->bottom(), curr->end(),
358 358 curr->top(),
359 359 curr->prev_top_at_mark_start(),
360 360 curr->next_top_at_mark_start(),
361 361 curr->top_at_conc_mark_count(),
362 362 curr->age_in_surv_rate_group_cond(),
363 363 curr->is_young(),
364 364 curr->is_survivor());
365 365 curr = curr->get_next_young_region();
366 366 }
367 367 }
368 368
369 369 gclog_or_tty->print_cr("");
370 370 }
371 371
372 372 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
373 373 {
374 374 // Claim the right to put the region on the dirty cards region list
375 375 // by installing a self pointer.
376 376 HeapRegion* next = hr->get_next_dirty_cards_region();
377 377 if (next == NULL) {
378 378 HeapRegion* res = (HeapRegion*)
379 379 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
380 380 NULL);
381 381 if (res == NULL) {
382 382 HeapRegion* head;
383 383 do {
384 384 // Put the region to the dirty cards region list.
385 385 head = _dirty_cards_region_list;
386 386 next = (HeapRegion*)
387 387 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
388 388 if (next == head) {
389 389 assert(hr->get_next_dirty_cards_region() == hr,
390 390 "hr->get_next_dirty_cards_region() != hr");
391 391 if (next == NULL) {
392 392 // The last region in the list points to itself.
393 393 hr->set_next_dirty_cards_region(hr);
394 394 } else {
395 395 hr->set_next_dirty_cards_region(next);
396 396 }
397 397 }
398 398 } while (next != head);
399 399 }
400 400 }
401 401 }
402 402
403 403 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
404 404 {
405 405 HeapRegion* head;
406 406 HeapRegion* hr;
407 407 do {
408 408 head = _dirty_cards_region_list;
409 409 if (head == NULL) {
410 410 return NULL;
411 411 }
412 412 HeapRegion* new_head = head->get_next_dirty_cards_region();
413 413 if (head == new_head) {
414 414 // The last region.
415 415 new_head = NULL;
416 416 }
417 417 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
418 418 head);
419 419 } while (hr != head);
420 420 assert(hr != NULL, "invariant");
421 421 hr->set_next_dirty_cards_region(NULL);
422 422 return hr;
423 423 }
424 424
425 425 void G1CollectedHeap::stop_conc_gc_threads() {
426 426 _cg1r->stop();
427 427 _cmThread->stop();
428 428 }
429 429
430 430 void G1CollectedHeap::check_ct_logs_at_safepoint() {
431 431 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
432 432 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
433 433
434 434 // Count the dirty cards at the start.
435 435 CountNonCleanMemRegionClosure count1(this);
436 436 ct_bs->mod_card_iterate(&count1);
437 437 int orig_count = count1.n();
438 438
439 439 // First clear the logged cards.
440 440 ClearLoggedCardTableEntryClosure clear;
441 441 dcqs.set_closure(&clear);
442 442 dcqs.apply_closure_to_all_completed_buffers();
443 443 dcqs.iterate_closure_all_threads(false);
444 444 clear.print_histo();
445 445
446 446 // Now ensure that there's no dirty cards.
447 447 CountNonCleanMemRegionClosure count2(this);
448 448 ct_bs->mod_card_iterate(&count2);
449 449 if (count2.n() != 0) {
450 450 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
451 451 count2.n(), orig_count);
452 452 }
453 453 guarantee(count2.n() == 0, "Card table should be clean.");
454 454
455 455 RedirtyLoggedCardTableEntryClosure redirty;
456 456 JavaThread::dirty_card_queue_set().set_closure(&redirty);
457 457 dcqs.apply_closure_to_all_completed_buffers();
458 458 dcqs.iterate_closure_all_threads(false);
459 459 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
460 460 clear.calls(), orig_count);
461 461 guarantee(redirty.calls() == clear.calls(),
462 462 "Or else mechanism is broken.");
463 463
464 464 CountNonCleanMemRegionClosure count3(this);
465 465 ct_bs->mod_card_iterate(&count3);
466 466 if (count3.n() != orig_count) {
467 467 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
468 468 orig_count, count3.n());
469 469 guarantee(count3.n() >= orig_count, "Should have restored them all.");
470 470 }
471 471
472 472 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
473 473 }
474 474
475 475 // Private class members.
476 476
477 477 G1CollectedHeap* G1CollectedHeap::_g1h;
478 478
479 479 // Private methods.
480 480
481 481 HeapRegion*
482 482 G1CollectedHeap::new_region_try_secondary_free_list() {
483 483 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
484 484 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
485 485 if (!_secondary_free_list.is_empty()) {
486 486 if (G1ConcRegionFreeingVerbose) {
487 487 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
488 488 "secondary_free_list has "SIZE_FORMAT" entries",
489 489 _secondary_free_list.length());
490 490 }
491 491 // It looks as if there are free regions available on the
492 492 // secondary_free_list. Let's move them to the free_list and try
493 493 // again to allocate from it.
494 494 append_secondary_free_list();
495 495
496 496 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
497 497 "empty we should have moved at least one entry to the free_list");
498 498 HeapRegion* res = _free_list.remove_head();
499 499 if (G1ConcRegionFreeingVerbose) {
500 500 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
501 501 "allocated "HR_FORMAT" from secondary_free_list",
502 502 HR_FORMAT_PARAMS(res));
503 503 }
504 504 return res;
505 505 }
506 506
507 507 // Wait here until we get notifed either when (a) there are no
508 508 // more free regions coming or (b) some regions have been moved on
509 509 // the secondary_free_list.
510 510 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
511 511 }
512 512
513 513 if (G1ConcRegionFreeingVerbose) {
514 514 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
515 515 "could not allocate from secondary_free_list");
516 516 }
517 517 return NULL;
518 518 }
519 519
520 520 HeapRegion* G1CollectedHeap::new_region_work(size_t word_size,
521 521 bool do_expand) {
522 522 assert(!isHumongous(word_size) ||
523 523 word_size <= (size_t) HeapRegion::GrainWords,
524 524 "the only time we use this to allocate a humongous region is "
525 525 "when we are allocating a single humongous region");
526 526
527 527 HeapRegion* res;
528 528 if (G1StressConcRegionFreeing) {
529 529 if (!_secondary_free_list.is_empty()) {
530 530 if (G1ConcRegionFreeingVerbose) {
531 531 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
532 532 "forced to look at the secondary_free_list");
533 533 }
534 534 res = new_region_try_secondary_free_list();
535 535 if (res != NULL) {
536 536 return res;
537 537 }
538 538 }
539 539 }
540 540 res = _free_list.remove_head_or_null();
541 541 if (res == NULL) {
542 542 if (G1ConcRegionFreeingVerbose) {
543 543 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
544 544 "res == NULL, trying the secondary_free_list");
545 545 }
546 546 res = new_region_try_secondary_free_list();
547 547 }
548 548 if (res == NULL && do_expand) {
549 549 if (expand(word_size * HeapWordSize)) {
550 550 // The expansion succeeded and so we should have at least one
551 551 // region on the free list.
552 552 res = _free_list.remove_head();
553 553 }
554 554 }
555 555 if (res != NULL) {
556 556 if (G1PrintHeapRegions) {
557 557 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT","PTR_FORMAT"], "
558 558 "top "PTR_FORMAT, res->hrs_index(),
559 559 res->bottom(), res->end(), res->top());
560 560 }
561 561 }
562 562 return res;
563 563 }
564 564
565 565 HeapRegion* G1CollectedHeap::new_gc_alloc_region(int purpose,
566 566 size_t word_size) {
567 567 HeapRegion* alloc_region = NULL;
568 568 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
569 569 alloc_region = new_region_work(word_size, true /* do_expand */);
570 570 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
571 571 alloc_region->set_survivor();
572 572 }
573 573 ++_gc_alloc_region_counts[purpose];
574 574 } else {
575 575 g1_policy()->note_alloc_region_limit_reached(purpose);
576 576 }
577 577 return alloc_region;
578 578 }
579 579
580 580 int G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
581 581 size_t word_size) {
582 582 assert(isHumongous(word_size), "word_size should be humongous");
583 583 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
584 584
585 585 int first = -1;
586 586 if (num_regions == 1) {
587 587 // Only one region to allocate, no need to go through the slower
588 588 // path. The caller will attempt the expasion if this fails, so
589 589 // let's not try to expand here too.
590 590 HeapRegion* hr = new_region_work(word_size, false /* do_expand */);
591 591 if (hr != NULL) {
592 592 first = hr->hrs_index();
593 593 } else {
594 594 first = -1;
595 595 }
596 596 } else {
597 597 // We can't allocate humongous regions while cleanupComplete() is
598 598 // running, since some of the regions we find to be empty might not
599 599 // yet be added to the free list and it is not straightforward to
600 600 // know which list they are on so that we can remove them. Note
601 601 // that we only need to do this if we need to allocate more than
602 602 // one region to satisfy the current humongous allocation
603 603 // request. If we are only allocating one region we use the common
604 604 // region allocation code (see above).
605 605 wait_while_free_regions_coming();
606 606 append_secondary_free_list_if_not_empty_with_lock();
607 607
608 608 if (free_regions() >= num_regions) {
609 609 first = _hrs->find_contiguous(num_regions);
610 610 if (first != -1) {
611 611 for (int i = first; i < first + (int) num_regions; ++i) {
612 612 HeapRegion* hr = _hrs->at(i);
613 613 assert(hr->is_empty(), "sanity");
614 614 assert(is_on_master_free_list(hr), "sanity");
615 615 hr->set_pending_removal(true);
616 616 }
617 617 _free_list.remove_all_pending(num_regions);
618 618 }
619 619 }
620 620 }
621 621 return first;
622 622 }
623 623
624 624 HeapWord*
625 625 G1CollectedHeap::humongous_obj_allocate_initialize_regions(int first,
626 626 size_t num_regions,
627 627 size_t word_size) {
628 628 assert(first != -1, "pre-condition");
629 629 assert(isHumongous(word_size), "word_size should be humongous");
630 630 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
631 631
632 632 // Index of last region in the series + 1.
633 633 int last = first + (int) num_regions;
634 634
635 635 // We need to initialize the region(s) we just discovered. This is
636 636 // a bit tricky given that it can happen concurrently with
637 637 // refinement threads refining cards on these regions and
638 638 // potentially wanting to refine the BOT as they are scanning
639 639 // those cards (this can happen shortly after a cleanup; see CR
640 640 // 6991377). So we have to set up the region(s) carefully and in
641 641 // a specific order.
642 642
643 643 // The word size sum of all the regions we will allocate.
644 644 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
645 645 assert(word_size <= word_size_sum, "sanity");
646 646
647 647 // This will be the "starts humongous" region.
648 648 HeapRegion* first_hr = _hrs->at(first);
649 649 // The header of the new object will be placed at the bottom of
650 650 // the first region.
651 651 HeapWord* new_obj = first_hr->bottom();
652 652 // This will be the new end of the first region in the series that
653 653 // should also match the end of the last region in the seriers.
654 654 HeapWord* new_end = new_obj + word_size_sum;
655 655 // This will be the new top of the first region that will reflect
656 656 // this allocation.
657 657 HeapWord* new_top = new_obj + word_size;
658 658
659 659 // First, we need to zero the header of the space that we will be
660 660 // allocating. When we update top further down, some refinement
661 661 // threads might try to scan the region. By zeroing the header we
662 662 // ensure that any thread that will try to scan the region will
663 663 // come across the zero klass word and bail out.
664 664 //
665 665 // NOTE: It would not have been correct to have used
666 666 // CollectedHeap::fill_with_object() and make the space look like
667 667 // an int array. The thread that is doing the allocation will
668 668 // later update the object header to a potentially different array
669 669 // type and, for a very short period of time, the klass and length
670 670 // fields will be inconsistent. This could cause a refinement
671 671 // thread to calculate the object size incorrectly.
672 672 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
673 673
674 674 // We will set up the first region as "starts humongous". This
675 675 // will also update the BOT covering all the regions to reflect
676 676 // that there is a single object that starts at the bottom of the
677 677 // first region.
678 678 first_hr->set_startsHumongous(new_top, new_end);
679 679
680 680 // Then, if there are any, we will set up the "continues
681 681 // humongous" regions.
682 682 HeapRegion* hr = NULL;
683 683 for (int i = first + 1; i < last; ++i) {
684 684 hr = _hrs->at(i);
685 685 hr->set_continuesHumongous(first_hr);
686 686 }
687 687 // If we have "continues humongous" regions (hr != NULL), then the
688 688 // end of the last one should match new_end.
689 689 assert(hr == NULL || hr->end() == new_end, "sanity");
690 690
691 691 // Up to this point no concurrent thread would have been able to
692 692 // do any scanning on any region in this series. All the top
693 693 // fields still point to bottom, so the intersection between
694 694 // [bottom,top] and [card_start,card_end] will be empty. Before we
695 695 // update the top fields, we'll do a storestore to make sure that
696 696 // no thread sees the update to top before the zeroing of the
697 697 // object header and the BOT initialization.
698 698 OrderAccess::storestore();
699 699
700 700 // Now that the BOT and the object header have been initialized,
701 701 // we can update top of the "starts humongous" region.
702 702 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
703 703 "new_top should be in this region");
704 704 first_hr->set_top(new_top);
705 705
706 706 // Now, we will update the top fields of the "continues humongous"
707 707 // regions. The reason we need to do this is that, otherwise,
708 708 // these regions would look empty and this will confuse parts of
709 709 // G1. For example, the code that looks for a consecutive number
710 710 // of empty regions will consider them empty and try to
711 711 // re-allocate them. We can extend is_empty() to also include
712 712 // !continuesHumongous(), but it is easier to just update the top
713 713 // fields here. The way we set top for all regions (i.e., top ==
714 714 // end for all regions but the last one, top == new_top for the
715 715 // last one) is actually used when we will free up the humongous
716 716 // region in free_humongous_region().
717 717 hr = NULL;
718 718 for (int i = first + 1; i < last; ++i) {
719 719 hr = _hrs->at(i);
720 720 if ((i + 1) == last) {
721 721 // last continues humongous region
722 722 assert(hr->bottom() < new_top && new_top <= hr->end(),
723 723 "new_top should fall on this region");
724 724 hr->set_top(new_top);
725 725 } else {
726 726 // not last one
727 727 assert(new_top > hr->end(), "new_top should be above this region");
728 728 hr->set_top(hr->end());
729 729 }
730 730 }
731 731 // If we have continues humongous regions (hr != NULL), then the
732 732 // end of the last one should match new_end and its top should
733 733 // match new_top.
734 734 assert(hr == NULL ||
735 735 (hr->end() == new_end && hr->top() == new_top), "sanity");
736 736
737 737 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
738 738 _summary_bytes_used += first_hr->used();
739 739 _humongous_set.add(first_hr);
740 740
741 741 return new_obj;
742 742 }
743 743
744 744 // If could fit into free regions w/o expansion, try.
745 745 // Otherwise, if can expand, do so.
746 746 // Otherwise, if using ex regions might help, try with ex given back.
747 747 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
748 748 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
749 749
750 750 verify_region_sets_optional();
751 751
752 752 size_t num_regions =
753 753 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
754 754 size_t x_size = expansion_regions();
755 755 size_t fs = _hrs->free_suffix();
756 756 int first = humongous_obj_allocate_find_first(num_regions, word_size);
757 757 if (first == -1) {
758 758 // The only thing we can do now is attempt expansion.
759 759 if (fs + x_size >= num_regions) {
760 760 // If the number of regions we're trying to allocate for this
761 761 // object is at most the number of regions in the free suffix,
762 762 // then the call to humongous_obj_allocate_find_first() above
763 763 // should have succeeded and we wouldn't be here.
764 764 //
765 765 // We should only be trying to expand when the free suffix is
766 766 // not sufficient for the object _and_ we have some expansion
767 767 // room available.
768 768 assert(num_regions > fs, "earlier allocation should have succeeded");
769 769
770 770 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
771 771 first = humongous_obj_allocate_find_first(num_regions, word_size);
772 772 // If the expansion was successful then the allocation
773 773 // should have been successful.
774 774 assert(first != -1, "this should have worked");
775 775 }
776 776 }
777 777 }
778 778
779 779 HeapWord* result = NULL;
780 780 if (first != -1) {
781 781 result =
782 782 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
783 783 assert(result != NULL, "it should always return a valid result");
784 784 }
785 785
786 786 verify_region_sets_optional();
787 787
788 788 return result;
789 789 }
790 790
791 791 void
792 792 G1CollectedHeap::retire_cur_alloc_region(HeapRegion* cur_alloc_region) {
793 793 // Other threads might still be trying to allocate using CASes out
794 794 // of the region we are retiring, as they can do so without holding
795 795 // the Heap_lock. So we first have to make sure that noone else can
796 796 // allocate in it by doing a maximal allocation. Even if our CAS
797 797 // attempt fails a few times, we'll succeed sooner or later given
798 798 // that a failed CAS attempt mean that the region is getting closed
799 799 // to being full (someone else succeeded in allocating into it).
800 800 size_t free_word_size = cur_alloc_region->free() / HeapWordSize;
801 801
802 802 // This is the minimum free chunk we can turn into a dummy
803 803 // object. If the free space falls below this, then noone can
804 804 // allocate in this region anyway (all allocation requests will be
805 805 // of a size larger than this) so we won't have to perform the dummy
806 806 // allocation.
807 807 size_t min_word_size_to_fill = CollectedHeap::min_fill_size();
808 808
809 809 while (free_word_size >= min_word_size_to_fill) {
810 810 HeapWord* dummy =
811 811 cur_alloc_region->par_allocate_no_bot_updates(free_word_size);
812 812 if (dummy != NULL) {
813 813 // If the allocation was successful we should fill in the space.
814 814 CollectedHeap::fill_with_object(dummy, free_word_size);
815 815 break;
816 816 }
817 817
818 818 free_word_size = cur_alloc_region->free() / HeapWordSize;
819 819 // It's also possible that someone else beats us to the
820 820 // allocation and they fill up the region. In that case, we can
821 821 // just get out of the loop
822 822 }
823 823 assert(cur_alloc_region->free() / HeapWordSize < min_word_size_to_fill,
824 824 "sanity");
825 825
826 826 retire_cur_alloc_region_common(cur_alloc_region);
827 827 assert(_cur_alloc_region == NULL, "post-condition");
828 828 }
829 829
830 830 // See the comment in the .hpp file about the locking protocol and
831 831 // assumptions of this method (and other related ones).
832 832 HeapWord*
833 833 G1CollectedHeap::replace_cur_alloc_region_and_allocate(size_t word_size,
834 834 bool at_safepoint,
835 835 bool do_dirtying,
836 836 bool can_expand) {
837 837 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
838 838 assert(_cur_alloc_region == NULL,
839 839 "replace_cur_alloc_region_and_allocate() should only be called "
840 840 "after retiring the previous current alloc region");
841 841 assert(SafepointSynchronize::is_at_safepoint() == at_safepoint,
842 842 "at_safepoint and is_at_safepoint() should be a tautology");
843 843 assert(!can_expand || g1_policy()->can_expand_young_list(),
844 844 "we should not call this method with can_expand == true if "
845 845 "we are not allowed to expand the young gen");
846 846
847 847 if (can_expand || !g1_policy()->is_young_list_full()) {
848 848 HeapRegion* new_cur_alloc_region = new_alloc_region(word_size);
849 849 if (new_cur_alloc_region != NULL) {
850 850 assert(new_cur_alloc_region->is_empty(),
851 851 "the newly-allocated region should be empty, "
852 852 "as right now we only allocate new regions out of the free list");
853 853 g1_policy()->update_region_num(true /* next_is_young */);
854 854 set_region_short_lived_locked(new_cur_alloc_region);
855 855
856 856 assert(!new_cur_alloc_region->isHumongous(),
857 857 "Catch a regression of this bug.");
858 858
859 859 // We need to ensure that the stores to _cur_alloc_region and,
860 860 // subsequently, to top do not float above the setting of the
861 861 // young type.
862 862 OrderAccess::storestore();
863 863
864 864 // Now, perform the allocation out of the region we just
865 865 // allocated. Note that noone else can access that region at
866 866 // this point (as _cur_alloc_region has not been updated yet),
867 867 // so we can just go ahead and do the allocation without any
868 868 // atomics (and we expect this allocation attempt to
869 869 // suceeded). Given that other threads can attempt an allocation
870 870 // with a CAS and without needing the Heap_lock, if we assigned
871 871 // the new region to _cur_alloc_region before first allocating
872 872 // into it other threads might have filled up the new region
873 873 // before we got a chance to do the allocation ourselves. In
874 874 // that case, we would have needed to retire the region, grab a
875 875 // new one, and go through all this again. Allocating out of the
876 876 // new region before assigning it to _cur_alloc_region avoids
877 877 // all this.
878 878 HeapWord* result =
879 879 new_cur_alloc_region->allocate_no_bot_updates(word_size);
880 880 assert(result != NULL, "we just allocate out of an empty region "
881 881 "so allocation should have been successful");
882 882 assert(is_in(result), "result should be in the heap");
883 883
884 884 // Now make sure that the store to _cur_alloc_region does not
885 885 // float above the store to top.
886 886 OrderAccess::storestore();
887 887 _cur_alloc_region = new_cur_alloc_region;
888 888
889 889 if (!at_safepoint) {
890 890 Heap_lock->unlock();
891 891 }
892 892
893 893 // do the dirtying, if necessary, after we release the Heap_lock
894 894 if (do_dirtying) {
895 895 dirty_young_block(result, word_size);
896 896 }
897 897 return result;
898 898 }
899 899 }
900 900
901 901 assert(_cur_alloc_region == NULL, "we failed to allocate a new current "
902 902 "alloc region, it should still be NULL");
903 903 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
904 904 return NULL;
905 905 }
906 906
907 907 // See the comment in the .hpp file about the locking protocol and
908 908 // assumptions of this method (and other related ones).
909 909 HeapWord*
910 910 G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
911 911 assert_heap_locked_and_not_at_safepoint();
912 912 assert(!isHumongous(word_size), "attempt_allocation_slow() should not be "
913 913 "used for humongous allocations");
914 914
915 915 // We should only reach here when we were unable to allocate
916 916 // otherwise. So, we should have not active current alloc region.
917 917 assert(_cur_alloc_region == NULL, "current alloc region should be NULL");
918 918
919 919 // We will loop while succeeded is false, which means that we tried
920 920 // to do a collection, but the VM op did not succeed. So, when we
921 921 // exit the loop, either one of the allocation attempts was
922 922 // successful, or we succeeded in doing the VM op but which was
923 923 // unable to allocate after the collection.
924 924 for (int try_count = 1; /* we'll return or break */; try_count += 1) {
925 925 bool succeeded = true;
926 926
927 927 // Every time we go round the loop we should be holding the Heap_lock.
928 928 assert_heap_locked();
929 929
930 930 if (GC_locker::is_active_and_needs_gc()) {
931 931 // We are locked out of GC because of the GC locker. We can
932 932 // allocate a new region only if we can expand the young gen.
933 933
934 934 if (g1_policy()->can_expand_young_list()) {
935 935 // Yes, we are allowed to expand the young gen. Let's try to
936 936 // allocate a new current alloc region.
937 937 HeapWord* result =
938 938 replace_cur_alloc_region_and_allocate(word_size,
939 939 false, /* at_safepoint */
940 940 true, /* do_dirtying */
941 941 true /* can_expand */);
942 942 if (result != NULL) {
943 943 assert_heap_not_locked();
944 944 return result;
945 945 }
946 946 }
947 947 // We could not expand the young gen further (or we could but we
948 948 // failed to allocate a new region). We'll stall until the GC
949 949 // locker forces a GC.
950 950
951 951 // If this thread is not in a jni critical section, we stall
952 952 // the requestor until the critical section has cleared and
953 953 // GC allowed. When the critical section clears, a GC is
954 954 // initiated by the last thread exiting the critical section; so
955 955 // we retry the allocation sequence from the beginning of the loop,
956 956 // rather than causing more, now probably unnecessary, GC attempts.
957 957 JavaThread* jthr = JavaThread::current();
958 958 assert(jthr != NULL, "sanity");
959 959 if (jthr->in_critical()) {
960 960 if (CheckJNICalls) {
961 961 fatal("Possible deadlock due to allocating while"
962 962 " in jni critical section");
963 963 }
964 964 // We are returning NULL so the protocol is that we're still
965 965 // holding the Heap_lock.
966 966 assert_heap_locked();
967 967 return NULL;
968 968 }
969 969
970 970 Heap_lock->unlock();
971 971 GC_locker::stall_until_clear();
972 972
973 973 // No need to relock the Heap_lock. We'll fall off to the code
974 974 // below the else-statement which assumes that we are not
975 975 // holding the Heap_lock.
976 976 } else {
977 977 // We are not locked out. So, let's try to do a GC. The VM op
978 978 // will retry the allocation before it completes.
979 979
980 980 // Read the GC count while holding the Heap_lock
981 981 unsigned int gc_count_before = SharedHeap::heap()->total_collections();
982 982
983 983 Heap_lock->unlock();
984 984
985 985 HeapWord* result =
986 986 do_collection_pause(word_size, gc_count_before, &succeeded);
987 987 assert_heap_not_locked();
988 988 if (result != NULL) {
989 989 assert(succeeded, "the VM op should have succeeded");
990 990
991 991 // Allocations that take place on VM operations do not do any
992 992 // card dirtying and we have to do it here.
993 993 dirty_young_block(result, word_size);
994 994 return result;
995 995 }
996 996 }
997 997
998 998 // Both paths that get us here from above unlock the Heap_lock.
999 999 assert_heap_not_locked();
1000 1000
1001 1001 // We can reach here when we were unsuccessful in doing a GC,
1002 1002 // because another thread beat us to it, or because we were locked
1003 1003 // out of GC due to the GC locker. In either case a new alloc
1004 1004 // region might be available so we will retry the allocation.
1005 1005 HeapWord* result = attempt_allocation(word_size);
1006 1006 if (result != NULL) {
1007 1007 assert_heap_not_locked();
1008 1008 return result;
1009 1009 }
1010 1010
1011 1011 // So far our attempts to allocate failed. The only time we'll go
1012 1012 // around the loop and try again is if we tried to do a GC and the
1013 1013 // VM op that we tried to schedule was not successful because
1014 1014 // another thread beat us to it. If that happened it's possible
1015 1015 // that by the time we grabbed the Heap_lock again and tried to
1016 1016 // allocate other threads filled up the young generation, which
1017 1017 // means that the allocation attempt after the GC also failed. So,
1018 1018 // it's worth trying to schedule another GC pause.
1019 1019 if (succeeded) {
1020 1020 break;
1021 1021 }
1022 1022
1023 1023 // Give a warning if we seem to be looping forever.
1024 1024 if ((QueuedAllocationWarningCount > 0) &&
1025 1025 (try_count % QueuedAllocationWarningCount == 0)) {
1026 1026 warning("G1CollectedHeap::attempt_allocation_slow() "
1027 1027 "retries %d times", try_count);
1028 1028 }
1029 1029 }
1030 1030
1031 1031 assert_heap_locked();
1032 1032 return NULL;
1033 1033 }
1034 1034
1035 1035 // See the comment in the .hpp file about the locking protocol and
1036 1036 // assumptions of this method (and other related ones).
1037 1037 HeapWord*
1038 1038 G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1039 1039 bool at_safepoint) {
1040 1040 // This is the method that will allocate a humongous object. All
1041 1041 // allocation paths that attempt to allocate a humongous object
1042 1042 // should eventually reach here. Currently, the only paths are from
1043 1043 // mem_allocate() and attempt_allocation_at_safepoint().
1044 1044 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
1045 1045 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1046 1046 "should only be used for humongous allocations");
1047 1047 assert(SafepointSynchronize::is_at_safepoint() == at_safepoint,
1048 1048 "at_safepoint and is_at_safepoint() should be a tautology");
1049 1049
1050 1050 HeapWord* result = NULL;
1051 1051
1052 1052 // We will loop while succeeded is false, which means that we tried
1053 1053 // to do a collection, but the VM op did not succeed. So, when we
1054 1054 // exit the loop, either one of the allocation attempts was
1055 1055 // successful, or we succeeded in doing the VM op but which was
1056 1056 // unable to allocate after the collection.
1057 1057 for (int try_count = 1; /* we'll return or break */; try_count += 1) {
1058 1058 bool succeeded = true;
1059 1059
1060 1060 // Given that humongous objects are not allocated in young
1061 1061 // regions, we'll first try to do the allocation without doing a
1062 1062 // collection hoping that there's enough space in the heap.
1063 1063 result = humongous_obj_allocate(word_size);
1064 1064 assert(_cur_alloc_region == NULL || !_cur_alloc_region->isHumongous(),
1065 1065 "catch a regression of this bug.");
1066 1066 if (result != NULL) {
1067 1067 if (!at_safepoint) {
1068 1068 // If we're not at a safepoint, unlock the Heap_lock.
1069 1069 Heap_lock->unlock();
1070 1070 }
1071 1071 return result;
1072 1072 }
1073 1073
1074 1074 // If we failed to allocate the humongous object, we should try to
1075 1075 // do a collection pause (if we're allowed) in case it reclaims
1076 1076 // enough space for the allocation to succeed after the pause.
1077 1077 if (!at_safepoint) {
1078 1078 // Read the GC count while holding the Heap_lock
1079 1079 unsigned int gc_count_before = SharedHeap::heap()->total_collections();
1080 1080
1081 1081 // If we're allowed to do a collection we're not at a
1082 1082 // safepoint, so it is safe to unlock the Heap_lock.
1083 1083 Heap_lock->unlock();
1084 1084
1085 1085 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1086 1086 assert_heap_not_locked();
1087 1087 if (result != NULL) {
1088 1088 assert(succeeded, "the VM op should have succeeded");
1089 1089 return result;
1090 1090 }
1091 1091
1092 1092 // If we get here, the VM operation either did not succeed
1093 1093 // (i.e., another thread beat us to it) or it succeeded but
1094 1094 // failed to allocate the object.
1095 1095
1096 1096 // If we're allowed to do a collection we're not at a
1097 1097 // safepoint, so it is safe to lock the Heap_lock.
1098 1098 Heap_lock->lock();
1099 1099 }
1100 1100
1101 1101 assert(result == NULL, "otherwise we should have exited the loop earlier");
1102 1102
1103 1103 // So far our attempts to allocate failed. The only time we'll go
1104 1104 // around the loop and try again is if we tried to do a GC and the
1105 1105 // VM op that we tried to schedule was not successful because
1106 1106 // another thread beat us to it. That way it's possible that some
1107 1107 // space was freed up by the thread that successfully scheduled a
1108 1108 // GC. So it's worth trying to allocate again.
1109 1109 if (succeeded) {
1110 1110 break;
1111 1111 }
1112 1112
1113 1113 // Give a warning if we seem to be looping forever.
1114 1114 if ((QueuedAllocationWarningCount > 0) &&
1115 1115 (try_count % QueuedAllocationWarningCount == 0)) {
1116 1116 warning("G1CollectedHeap::attempt_allocation_humongous "
1117 1117 "retries %d times", try_count);
1118 1118 }
1119 1119 }
1120 1120
1121 1121 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
1122 1122 return NULL;
1123 1123 }
1124 1124
1125 1125 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1126 1126 bool expect_null_cur_alloc_region) {
1127 1127 assert_at_safepoint(true /* should_be_vm_thread */);
1128 1128 assert(_cur_alloc_region == NULL || !expect_null_cur_alloc_region,
1129 1129 err_msg("the current alloc region was unexpectedly found "
1130 1130 "to be non-NULL, cur alloc region: "PTR_FORMAT" "
1131 1131 "expect_null_cur_alloc_region: %d word_size: "SIZE_FORMAT,
1132 1132 _cur_alloc_region, expect_null_cur_alloc_region, word_size));
1133 1133
1134 1134 if (!isHumongous(word_size)) {
1135 1135 if (!expect_null_cur_alloc_region) {
1136 1136 HeapRegion* cur_alloc_region = _cur_alloc_region;
1137 1137 if (cur_alloc_region != NULL) {
1138 1138 // We are at a safepoint so no reason to use the MT-safe version.
1139 1139 HeapWord* result = cur_alloc_region->allocate_no_bot_updates(word_size);
1140 1140 if (result != NULL) {
1141 1141 assert(is_in(result), "result should be in the heap");
1142 1142
1143 1143 // We will not do any dirtying here. This is guaranteed to be
1144 1144 // called during a safepoint and the thread that scheduled the
1145 1145 // pause will do the dirtying if we return a non-NULL result.
1146 1146 return result;
1147 1147 }
1148 1148
1149 1149 retire_cur_alloc_region_common(cur_alloc_region);
1150 1150 }
1151 1151 }
1152 1152
1153 1153 assert(_cur_alloc_region == NULL,
1154 1154 "at this point we should have no cur alloc region");
1155 1155 return replace_cur_alloc_region_and_allocate(word_size,
1156 1156 true, /* at_safepoint */
1157 1157 false /* do_dirtying */,
1158 1158 false /* can_expand */);
1159 1159 } else {
1160 1160 return attempt_allocation_humongous(word_size,
1161 1161 true /* at_safepoint */);
1162 1162 }
1163 1163
1164 1164 ShouldNotReachHere();
1165 1165 }
1166 1166
1167 1167 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
1168 1168 assert_heap_not_locked_and_not_at_safepoint();
1169 1169 assert(!isHumongous(word_size), "we do not allow TLABs of humongous size");
1170 1170
1171 1171 // First attempt: Try allocating out of the current alloc region
1172 1172 // using a CAS. If that fails, take the Heap_lock and retry the
1173 1173 // allocation, potentially replacing the current alloc region.
1174 1174 HeapWord* result = attempt_allocation(word_size);
1175 1175 if (result != NULL) {
1176 1176 assert_heap_not_locked();
1177 1177 return result;
1178 1178 }
1179 1179
1180 1180 // Second attempt: Go to the slower path where we might try to
1181 1181 // schedule a collection.
1182 1182 result = attempt_allocation_slow(word_size);
1183 1183 if (result != NULL) {
1184 1184 assert_heap_not_locked();
1185 1185 return result;
1186 1186 }
1187 1187
1188 1188 assert_heap_locked();
1189 1189 // Need to unlock the Heap_lock before returning.
1190 1190 Heap_lock->unlock();
1191 1191 return NULL;
1192 1192 }
1193 1193
1194 1194 HeapWord*
1195 1195 G1CollectedHeap::mem_allocate(size_t word_size,
1196 1196 bool is_noref,
1197 1197 bool is_tlab,
1198 1198 bool* gc_overhead_limit_was_exceeded) {
1199 1199 assert_heap_not_locked_and_not_at_safepoint();
1200 1200 assert(!is_tlab, "mem_allocate() this should not be called directly "
1201 1201 "to allocate TLABs");
1202 1202
1203 1203 // Loop until the allocation is satisified,
1204 1204 // or unsatisfied after GC.
1205 1205 for (int try_count = 1; /* we'll return */; try_count += 1) {
1206 1206 unsigned int gc_count_before;
1207 1207 {
1208 1208 if (!isHumongous(word_size)) {
1209 1209 // First attempt: Try allocating out of the current alloc region
1210 1210 // using a CAS. If that fails, take the Heap_lock and retry the
1211 1211 // allocation, potentially replacing the current alloc region.
1212 1212 HeapWord* result = attempt_allocation(word_size);
1213 1213 if (result != NULL) {
1214 1214 assert_heap_not_locked();
1215 1215 return result;
1216 1216 }
1217 1217
1218 1218 assert_heap_locked();
1219 1219
1220 1220 // Second attempt: Go to the slower path where we might try to
1221 1221 // schedule a collection.
1222 1222 result = attempt_allocation_slow(word_size);
1223 1223 if (result != NULL) {
1224 1224 assert_heap_not_locked();
1225 1225 return result;
1226 1226 }
1227 1227 } else {
1228 1228 // attempt_allocation_humongous() requires the Heap_lock to be held.
1229 1229 Heap_lock->lock();
1230 1230
1231 1231 HeapWord* result = attempt_allocation_humongous(word_size,
1232 1232 false /* at_safepoint */);
1233 1233 if (result != NULL) {
1234 1234 assert_heap_not_locked();
1235 1235 return result;
1236 1236 }
1237 1237 }
1238 1238
1239 1239 assert_heap_locked();
1240 1240 // Read the gc count while the heap lock is held.
1241 1241 gc_count_before = SharedHeap::heap()->total_collections();
1242 1242
1243 1243 // Release the Heap_lock before attempting the collection.
1244 1244 Heap_lock->unlock();
1245 1245 }
1246 1246
1247 1247 // Create the garbage collection operation...
1248 1248 VM_G1CollectForAllocation op(gc_count_before, word_size);
1249 1249 // ...and get the VM thread to execute it.
1250 1250 VMThread::execute(&op);
1251 1251
1252 1252 assert_heap_not_locked();
1253 1253 if (op.prologue_succeeded() && op.pause_succeeded()) {
1254 1254 // If the operation was successful we'll return the result even
1255 1255 // if it is NULL. If the allocation attempt failed immediately
1256 1256 // after a Full GC, it's unlikely we'll be able to allocate now.
1257 1257 HeapWord* result = op.result();
1258 1258 if (result != NULL && !isHumongous(word_size)) {
1259 1259 // Allocations that take place on VM operations do not do any
1260 1260 // card dirtying and we have to do it here. We only have to do
1261 1261 // this for non-humongous allocations, though.
1262 1262 dirty_young_block(result, word_size);
1263 1263 }
1264 1264 return result;
1265 1265 } else {
1266 1266 assert(op.result() == NULL,
1267 1267 "the result should be NULL if the VM op did not succeed");
1268 1268 }
1269 1269
1270 1270 // Give a warning if we seem to be looping forever.
1271 1271 if ((QueuedAllocationWarningCount > 0) &&
1272 1272 (try_count % QueuedAllocationWarningCount == 0)) {
1273 1273 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
1274 1274 }
1275 1275 }
1276 1276
1277 1277 ShouldNotReachHere();
1278 1278 }
1279 1279
1280 1280 void G1CollectedHeap::abandon_cur_alloc_region() {
1281 1281 assert_at_safepoint(true /* should_be_vm_thread */);
1282 1282
1283 1283 HeapRegion* cur_alloc_region = _cur_alloc_region;
1284 1284 if (cur_alloc_region != NULL) {
1285 1285 assert(!cur_alloc_region->is_empty(),
1286 1286 "the current alloc region can never be empty");
1287 1287 assert(cur_alloc_region->is_young(),
1288 1288 "the current alloc region should be young");
1289 1289
1290 1290 retire_cur_alloc_region_common(cur_alloc_region);
1291 1291 }
1292 1292 assert(_cur_alloc_region == NULL, "post-condition");
1293 1293 }
1294 1294
1295 1295 void G1CollectedHeap::abandon_gc_alloc_regions() {
1296 1296 // first, make sure that the GC alloc region list is empty (it should!)
1297 1297 assert(_gc_alloc_region_list == NULL, "invariant");
1298 1298 release_gc_alloc_regions(true /* totally */);
1299 1299 }
1300 1300
1301 1301 class PostMCRemSetClearClosure: public HeapRegionClosure {
1302 1302 ModRefBarrierSet* _mr_bs;
1303 1303 public:
1304 1304 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1305 1305 bool doHeapRegion(HeapRegion* r) {
1306 1306 r->reset_gc_time_stamp();
1307 1307 if (r->continuesHumongous())
1308 1308 return false;
1309 1309 HeapRegionRemSet* hrrs = r->rem_set();
1310 1310 if (hrrs != NULL) hrrs->clear();
1311 1311 // You might think here that we could clear just the cards
1312 1312 // corresponding to the used region. But no: if we leave a dirty card
1313 1313 // in a region we might allocate into, then it would prevent that card
1314 1314 // from being enqueued, and cause it to be missed.
1315 1315 // Re: the performance cost: we shouldn't be doing full GC anyway!
1316 1316 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1317 1317 return false;
1318 1318 }
1319 1319 };
1320 1320
1321 1321
1322 1322 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1323 1323 ModRefBarrierSet* _mr_bs;
1324 1324 public:
1325 1325 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1326 1326 bool doHeapRegion(HeapRegion* r) {
1327 1327 if (r->continuesHumongous()) return false;
1328 1328 if (r->used_region().word_size() != 0) {
1329 1329 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1330 1330 }
1331 1331 return false;
1332 1332 }
1333 1333 };
1334 1334
1335 1335 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1336 1336 G1CollectedHeap* _g1h;
1337 1337 UpdateRSOopClosure _cl;
1338 1338 int _worker_i;
1339 1339 public:
1340 1340 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1341 1341 _cl(g1->g1_rem_set(), worker_i),
1342 1342 _worker_i(worker_i),
1343 1343 _g1h(g1)
1344 1344 { }
1345 1345
1346 1346 bool doHeapRegion(HeapRegion* r) {
1347 1347 if (!r->continuesHumongous()) {
1348 1348 _cl.set_from(r);
1349 1349 r->oop_iterate(&_cl);
1350 1350 }
1351 1351 return false;
1352 1352 }
1353 1353 };
1354 1354
1355 1355 class ParRebuildRSTask: public AbstractGangTask {
1356 1356 G1CollectedHeap* _g1;
1357 1357 public:
1358 1358 ParRebuildRSTask(G1CollectedHeap* g1)
1359 1359 : AbstractGangTask("ParRebuildRSTask"),
1360 1360 _g1(g1)
1361 1361 { }
1362 1362
1363 1363 void work(int i) {
1364 1364 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1365 1365 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1366 1366 HeapRegion::RebuildRSClaimValue);
1367 1367 }
1368 1368 };
1369 1369
1370 1370 bool G1CollectedHeap::do_collection(bool explicit_gc,
1371 1371 bool clear_all_soft_refs,
1372 1372 size_t word_size) {
1373 1373 assert_at_safepoint(true /* should_be_vm_thread */);
1374 1374
1375 1375 if (GC_locker::check_active_before_gc()) {
1376 1376 return false;
1377 1377 }
1378 1378
1379 1379 SvcGCMarker sgcm(SvcGCMarker::FULL);
1380 1380 ResourceMark rm;
1381 1381
1382 1382 if (PrintHeapAtGC) {
1383 1383 Universe::print_heap_before_gc();
1384 1384 }
1385 1385
1386 1386 verify_region_sets_optional();
1387 1387
1388 1388 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1389 1389 collector_policy()->should_clear_all_soft_refs();
1390 1390
1391 1391 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1392 1392
1393 1393 {
1394 1394 IsGCActiveMark x;
1395 1395
1396 1396 // Timing
1397 1397 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1398 1398 assert(!system_gc || explicit_gc, "invariant");
1399 1399 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1400 1400 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1401 1401 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1402 1402 PrintGC, true, gclog_or_tty);
1403 1403
1404 1404 TraceMemoryManagerStats tms(true /* fullGC */);
1405 1405
1406 1406 double start = os::elapsedTime();
1407 1407 g1_policy()->record_full_collection_start();
1408 1408
1409 1409 wait_while_free_regions_coming();
1410 1410 append_secondary_free_list_if_not_empty_with_lock();
1411 1411
1412 1412 gc_prologue(true);
1413 1413 increment_total_collections(true /* full gc */);
1414 1414
1415 1415 size_t g1h_prev_used = used();
1416 1416 assert(used() == recalculate_used(), "Should be equal");
1417 1417
1418 1418 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1419 1419 HandleMark hm; // Discard invalid handles created during verification
1420 1420 prepare_for_verify();
1421 1421 gclog_or_tty->print(" VerifyBeforeGC:");
1422 1422 Universe::verify(true);
1423 1423 }
1424 1424
1425 1425 COMPILER2_PRESENT(DerivedPointerTable::clear());
1426 1426
1427 1427 // We want to discover references, but not process them yet.
1428 1428 // This mode is disabled in
1429 1429 // instanceRefKlass::process_discovered_references if the
1430 1430 // generation does some collection work, or
1431 1431 // instanceRefKlass::enqueue_discovered_references if the
1432 1432 // generation returns without doing any work.
1433 1433 ref_processor()->disable_discovery();
1434 1434 ref_processor()->abandon_partial_discovery();
1435 1435 ref_processor()->verify_no_references_recorded();
1436 1436
1437 1437 // Abandon current iterations of concurrent marking and concurrent
1438 1438 // refinement, if any are in progress.
1439 1439 concurrent_mark()->abort();
1440 1440
1441 1441 // Make sure we'll choose a new allocation region afterwards.
1442 1442 abandon_cur_alloc_region();
1443 1443 abandon_gc_alloc_regions();
1444 1444 assert(_cur_alloc_region == NULL, "Invariant.");
1445 1445 g1_rem_set()->cleanupHRRS();
1446 1446 tear_down_region_lists();
1447 1447
1448 1448 // We may have added regions to the current incremental collection
1449 1449 // set between the last GC or pause and now. We need to clear the
1450 1450 // incremental collection set and then start rebuilding it afresh
1451 1451 // after this full GC.
1452 1452 abandon_collection_set(g1_policy()->inc_cset_head());
1453 1453 g1_policy()->clear_incremental_cset();
1454 1454 g1_policy()->stop_incremental_cset_building();
1455 1455
1456 1456 if (g1_policy()->in_young_gc_mode()) {
1457 1457 empty_young_list();
1458 1458 g1_policy()->set_full_young_gcs(true);
1459 1459 }
1460 1460
1461 1461 // See the comment in G1CollectedHeap::ref_processing_init() about
1462 1462 // how reference processing currently works in G1.
1463 1463
1464 1464 // Temporarily make reference _discovery_ single threaded (non-MT).
1465 1465 ReferenceProcessorMTMutator rp_disc_ser(ref_processor(), false);
1466 1466
1467 1467 // Temporarily make refs discovery atomic
1468 1468 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
1469 1469
1470 1470 // Temporarily clear _is_alive_non_header
1471 1471 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
1472 1472
1473 1473 ref_processor()->enable_discovery();
1474 1474 ref_processor()->setup_policy(do_clear_all_soft_refs);
1475 1475
1476 1476 // Do collection work
1477 1477 {
1478 1478 HandleMark hm; // Discard invalid handles created during gc
1479 1479 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
1480 1480 }
1481 1481 assert(free_regions() == 0, "we should not have added any free regions");
1482 1482 rebuild_region_lists();
1483 1483
1484 1484 _summary_bytes_used = recalculate_used();
1485 1485
1486 1486 ref_processor()->enqueue_discovered_references();
1487 1487
1488 1488 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1489 1489
1490 1490 MemoryService::track_memory_usage();
1491 1491
1492 1492 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1493 1493 HandleMark hm; // Discard invalid handles created during verification
1494 1494 gclog_or_tty->print(" VerifyAfterGC:");
1495 1495 prepare_for_verify();
1496 1496 Universe::verify(false);
1497 1497 }
1498 1498 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1499 1499
1500 1500 reset_gc_time_stamp();
1501 1501 // Since everything potentially moved, we will clear all remembered
1502 1502 // sets, and clear all cards. Later we will rebuild remebered
1503 1503 // sets. We will also reset the GC time stamps of the regions.
1504 1504 PostMCRemSetClearClosure rs_clear(mr_bs());
1505 1505 heap_region_iterate(&rs_clear);
1506 1506
1507 1507 // Resize the heap if necessary.
1508 1508 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1509 1509
1510 1510 if (_cg1r->use_cache()) {
1511 1511 _cg1r->clear_and_record_card_counts();
1512 1512 _cg1r->clear_hot_cache();
1513 1513 }
1514 1514
1515 1515 // Rebuild remembered sets of all regions.
1516 1516
1517 1517 if (G1CollectedHeap::use_parallel_gc_threads()) {
1518 1518 ParRebuildRSTask rebuild_rs_task(this);
1519 1519 assert(check_heap_region_claim_values(
1520 1520 HeapRegion::InitialClaimValue), "sanity check");
1521 1521 set_par_threads(workers()->total_workers());
1522 1522 workers()->run_task(&rebuild_rs_task);
1523 1523 set_par_threads(0);
1524 1524 assert(check_heap_region_claim_values(
1525 1525 HeapRegion::RebuildRSClaimValue), "sanity check");
1526 1526 reset_heap_region_claim_values();
1527 1527 } else {
1528 1528 RebuildRSOutOfRegionClosure rebuild_rs(this);
1529 1529 heap_region_iterate(&rebuild_rs);
1530 1530 }
1531 1531
1532 1532 if (PrintGC) {
1533 1533 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1534 1534 }
1535 1535
1536 1536 if (true) { // FIXME
1537 1537 // Ask the permanent generation to adjust size for full collections
1538 1538 perm()->compute_new_size();
1539 1539 }
1540 1540
1541 1541 // Start a new incremental collection set for the next pause
1542 1542 assert(g1_policy()->collection_set() == NULL, "must be");
1543 1543 g1_policy()->start_incremental_cset_building();
1544 1544
1545 1545 // Clear the _cset_fast_test bitmap in anticipation of adding
1546 1546 // regions to the incremental collection set for the next
1547 1547 // evacuation pause.
1548 1548 clear_cset_fast_test();
1549 1549
1550 1550 double end = os::elapsedTime();
1551 1551 g1_policy()->record_full_collection_end();
1552 1552
1553 1553 #ifdef TRACESPINNING
1554 1554 ParallelTaskTerminator::print_termination_counts();
1555 1555 #endif
1556 1556
1557 1557 gc_epilogue(true);
1558 1558
1559 1559 // Discard all rset updates
1560 1560 JavaThread::dirty_card_queue_set().abandon_logs();
1561 1561 assert(!G1DeferredRSUpdate
1562 1562 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1563 1563 }
1564 1564
1565 1565 if (g1_policy()->in_young_gc_mode()) {
1566 1566 _young_list->reset_sampled_info();
1567 1567 // At this point there should be no regions in the
1568 1568 // entire heap tagged as young.
1569 1569 assert( check_young_list_empty(true /* check_heap */),
1570 1570 "young list should be empty at this point");
1571 1571 }
1572 1572
1573 1573 // Update the number of full collections that have been completed.
1574 1574 increment_full_collections_completed(false /* concurrent */);
1575 1575
1576 1576 verify_region_sets_optional();
1577 1577
1578 1578 if (PrintHeapAtGC) {
1579 1579 Universe::print_heap_after_gc();
1580 1580 }
1581 1581
1582 1582 return true;
1583 1583 }
1584 1584
1585 1585 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1586 1586 // do_collection() will return whether it succeeded in performing
1587 1587 // the GC. Currently, there is no facility on the
1588 1588 // do_full_collection() API to notify the caller than the collection
1589 1589 // did not succeed (e.g., because it was locked out by the GC
1590 1590 // locker). So, right now, we'll ignore the return value.
1591 1591 bool dummy = do_collection(true, /* explicit_gc */
1592 1592 clear_all_soft_refs,
1593 1593 0 /* word_size */);
1594 1594 }
1595 1595
1596 1596 // This code is mostly copied from TenuredGeneration.
1597 1597 void
1598 1598 G1CollectedHeap::
1599 1599 resize_if_necessary_after_full_collection(size_t word_size) {
1600 1600 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1601 1601
1602 1602 // Include the current allocation, if any, and bytes that will be
1603 1603 // pre-allocated to support collections, as "used".
1604 1604 const size_t used_after_gc = used();
1605 1605 const size_t capacity_after_gc = capacity();
1606 1606 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1607 1607
1608 1608 // This is enforced in arguments.cpp.
1609 1609 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1610 1610 "otherwise the code below doesn't make sense");
1611 1611
1612 1612 // We don't have floating point command-line arguments
1613 1613 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1614 1614 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1615 1615 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1616 1616 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1617 1617
1618 1618 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1619 1619 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1620 1620
1621 1621 // We have to be careful here as these two calculations can overflow
1622 1622 // 32-bit size_t's.
1623 1623 double used_after_gc_d = (double) used_after_gc;
1624 1624 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1625 1625 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1626 1626
1627 1627 // Let's make sure that they are both under the max heap size, which
1628 1628 // by default will make them fit into a size_t.
1629 1629 double desired_capacity_upper_bound = (double) max_heap_size;
1630 1630 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1631 1631 desired_capacity_upper_bound);
1632 1632 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1633 1633 desired_capacity_upper_bound);
1634 1634
1635 1635 // We can now safely turn them into size_t's.
1636 1636 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1637 1637 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1638 1638
1639 1639 // This assert only makes sense here, before we adjust them
1640 1640 // with respect to the min and max heap size.
1641 1641 assert(minimum_desired_capacity <= maximum_desired_capacity,
1642 1642 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1643 1643 "maximum_desired_capacity = "SIZE_FORMAT,
1644 1644 minimum_desired_capacity, maximum_desired_capacity));
1645 1645
1646 1646 // Should not be greater than the heap max size. No need to adjust
1647 1647 // it with respect to the heap min size as it's a lower bound (i.e.,
1648 1648 // we'll try to make the capacity larger than it, not smaller).
1649 1649 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1650 1650 // Should not be less than the heap min size. No need to adjust it
1651 1651 // with respect to the heap max size as it's an upper bound (i.e.,
1652 1652 // we'll try to make the capacity smaller than it, not greater).
1653 1653 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1654 1654
1655 1655 if (PrintGC && Verbose) {
1656 1656 const double free_percentage =
1657 1657 (double) free_after_gc / (double) capacity_after_gc;
1658 1658 gclog_or_tty->print_cr("Computing new size after full GC ");
1659 1659 gclog_or_tty->print_cr(" "
1660 1660 " minimum_free_percentage: %6.2f",
1661 1661 minimum_free_percentage);
1662 1662 gclog_or_tty->print_cr(" "
1663 1663 " maximum_free_percentage: %6.2f",
1664 1664 maximum_free_percentage);
1665 1665 gclog_or_tty->print_cr(" "
1666 1666 " capacity: %6.1fK"
1667 1667 " minimum_desired_capacity: %6.1fK"
1668 1668 " maximum_desired_capacity: %6.1fK",
1669 1669 (double) capacity_after_gc / (double) K,
1670 1670 (double) minimum_desired_capacity / (double) K,
1671 1671 (double) maximum_desired_capacity / (double) K);
1672 1672 gclog_or_tty->print_cr(" "
1673 1673 " free_after_gc: %6.1fK"
1674 1674 " used_after_gc: %6.1fK",
1675 1675 (double) free_after_gc / (double) K,
1676 1676 (double) used_after_gc / (double) K);
1677 1677 gclog_or_tty->print_cr(" "
1678 1678 " free_percentage: %6.2f",
1679 1679 free_percentage);
1680 1680 }
1681 1681 if (capacity_after_gc < minimum_desired_capacity) {
1682 1682 // Don't expand unless it's significant
1683 1683 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1684 1684 if (expand(expand_bytes)) {
1685 1685 if (PrintGC && Verbose) {
1686 1686 gclog_or_tty->print_cr(" "
1687 1687 " expanding:"
1688 1688 " max_heap_size: %6.1fK"
1689 1689 " minimum_desired_capacity: %6.1fK"
1690 1690 " expand_bytes: %6.1fK",
1691 1691 (double) max_heap_size / (double) K,
1692 1692 (double) minimum_desired_capacity / (double) K,
1693 1693 (double) expand_bytes / (double) K);
1694 1694 }
1695 1695 }
1696 1696
1697 1697 // No expansion, now see if we want to shrink
1698 1698 } else if (capacity_after_gc > maximum_desired_capacity) {
1699 1699 // Capacity too large, compute shrinking size
1700 1700 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1701 1701 shrink(shrink_bytes);
1702 1702 if (PrintGC && Verbose) {
1703 1703 gclog_or_tty->print_cr(" "
1704 1704 " shrinking:"
1705 1705 " min_heap_size: %6.1fK"
1706 1706 " maximum_desired_capacity: %6.1fK"
1707 1707 " shrink_bytes: %6.1fK",
1708 1708 (double) min_heap_size / (double) K,
1709 1709 (double) maximum_desired_capacity / (double) K,
1710 1710 (double) shrink_bytes / (double) K);
1711 1711 }
1712 1712 }
1713 1713 }
1714 1714
1715 1715
1716 1716 HeapWord*
1717 1717 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1718 1718 bool* succeeded) {
1719 1719 assert_at_safepoint(true /* should_be_vm_thread */);
1720 1720
1721 1721 *succeeded = true;
1722 1722 // Let's attempt the allocation first.
1723 1723 HeapWord* result = attempt_allocation_at_safepoint(word_size,
1724 1724 false /* expect_null_cur_alloc_region */);
1725 1725 if (result != NULL) {
1726 1726 assert(*succeeded, "sanity");
1727 1727 return result;
1728 1728 }
1729 1729
1730 1730 // In a G1 heap, we're supposed to keep allocation from failing by
1731 1731 // incremental pauses. Therefore, at least for now, we'll favor
1732 1732 // expansion over collection. (This might change in the future if we can
1733 1733 // do something smarter than full collection to satisfy a failed alloc.)
1734 1734 result = expand_and_allocate(word_size);
1735 1735 if (result != NULL) {
1736 1736 assert(*succeeded, "sanity");
1737 1737 return result;
1738 1738 }
1739 1739
1740 1740 // Expansion didn't work, we'll try to do a Full GC.
1741 1741 bool gc_succeeded = do_collection(false, /* explicit_gc */
1742 1742 false, /* clear_all_soft_refs */
1743 1743 word_size);
1744 1744 if (!gc_succeeded) {
1745 1745 *succeeded = false;
1746 1746 return NULL;
1747 1747 }
1748 1748
1749 1749 // Retry the allocation
1750 1750 result = attempt_allocation_at_safepoint(word_size,
1751 1751 true /* expect_null_cur_alloc_region */);
1752 1752 if (result != NULL) {
1753 1753 assert(*succeeded, "sanity");
1754 1754 return result;
1755 1755 }
1756 1756
1757 1757 // Then, try a Full GC that will collect all soft references.
1758 1758 gc_succeeded = do_collection(false, /* explicit_gc */
1759 1759 true, /* clear_all_soft_refs */
1760 1760 word_size);
1761 1761 if (!gc_succeeded) {
1762 1762 *succeeded = false;
1763 1763 return NULL;
1764 1764 }
1765 1765
1766 1766 // Retry the allocation once more
1767 1767 result = attempt_allocation_at_safepoint(word_size,
1768 1768 true /* expect_null_cur_alloc_region */);
1769 1769 if (result != NULL) {
1770 1770 assert(*succeeded, "sanity");
1771 1771 return result;
1772 1772 }
1773 1773
1774 1774 assert(!collector_policy()->should_clear_all_soft_refs(),
1775 1775 "Flag should have been handled and cleared prior to this point");
1776 1776
1777 1777 // What else? We might try synchronous finalization later. If the total
1778 1778 // space available is large enough for the allocation, then a more
1779 1779 // complete compaction phase than we've tried so far might be
1780 1780 // appropriate.
1781 1781 assert(*succeeded, "sanity");
1782 1782 return NULL;
1783 1783 }
1784 1784
1785 1785 // Attempting to expand the heap sufficiently
1786 1786 // to support an allocation of the given "word_size". If
1787 1787 // successful, perform the allocation and return the address of the
1788 1788 // allocated block, or else "NULL".
1789 1789
1790 1790 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1791 1791 assert_at_safepoint(true /* should_be_vm_thread */);
1792 1792
1793 1793 verify_region_sets_optional();
1794 1794
1795 1795 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1796 1796 if (expand(expand_bytes)) {
1797 1797 verify_region_sets_optional();
1798 1798 return attempt_allocation_at_safepoint(word_size,
1799 1799 false /* expect_null_cur_alloc_region */);
1800 1800 }
1801 1801 return NULL;
1802 1802 }
1803 1803
1804 1804 bool G1CollectedHeap::expand(size_t expand_bytes) {
1805 1805 size_t old_mem_size = _g1_storage.committed_size();
1806 1806 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1807 1807 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1808 1808 HeapRegion::GrainBytes);
1809 1809
1810 1810 if (Verbose && PrintGC) {
1811 1811 gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK",
1812 1812 old_mem_size/K, aligned_expand_bytes/K);
1813 1813 }
1814 1814
1815 1815 HeapWord* old_end = (HeapWord*)_g1_storage.high();
1816 1816 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1817 1817 if (successful) {
1818 1818 HeapWord* new_end = (HeapWord*)_g1_storage.high();
1819 1819
1820 1820 // Expand the committed region.
1821 1821 _g1_committed.set_end(new_end);
1822 1822
1823 1823 // Tell the cardtable about the expansion.
1824 1824 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1825 1825
1826 1826 // And the offset table as well.
1827 1827 _bot_shared->resize(_g1_committed.word_size());
1828 1828
1829 1829 expand_bytes = aligned_expand_bytes;
1830 1830 HeapWord* base = old_end;
1831 1831
1832 1832 // Create the heap regions for [old_end, new_end)
1833 1833 while (expand_bytes > 0) {
1834 1834 HeapWord* high = base + HeapRegion::GrainWords;
1835 1835
1836 1836 // Create a new HeapRegion.
1837 1837 MemRegion mr(base, high);
1838 1838 bool is_zeroed = !_g1_max_committed.contains(base);
1839 1839 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1840 1840
1841 1841 // Add it to the HeapRegionSeq.
1842 1842 _hrs->insert(hr);
1843 1843 _free_list.add_as_tail(hr);
1844 1844
1845 1845 // And we used up an expansion region to create it.
1846 1846 _expansion_regions--;
1847 1847
1848 1848 expand_bytes -= HeapRegion::GrainBytes;
1849 1849 base += HeapRegion::GrainWords;
1850 1850 }
1851 1851 assert(base == new_end, "sanity");
1852 1852
1853 1853 // Now update max_committed if necessary.
1854 1854 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), new_end));
1855 1855
1856 1856 } else {
1857 1857 // The expansion of the virtual storage space was unsuccessful.
1858 1858 // Let's see if it was because we ran out of swap.
1859 1859 if (G1ExitOnExpansionFailure &&
1860 1860 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1861 1861 // We had head room...
1862 1862 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1863 1863 }
1864 1864 }
1865 1865
1866 1866 if (Verbose && PrintGC) {
1867 1867 size_t new_mem_size = _g1_storage.committed_size();
1868 1868 gclog_or_tty->print_cr("...%s, expanded to %ldK",
1869 1869 (successful ? "Successful" : "Failed"),
1870 1870 new_mem_size/K);
1871 1871 }
1872 1872 return successful;
1873 1873 }
1874 1874
1875 1875 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1876 1876 {
1877 1877 size_t old_mem_size = _g1_storage.committed_size();
1878 1878 size_t aligned_shrink_bytes =
1879 1879 ReservedSpace::page_align_size_down(shrink_bytes);
1880 1880 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1881 1881 HeapRegion::GrainBytes);
1882 1882 size_t num_regions_deleted = 0;
1883 1883 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1884 1884
1885 1885 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1886 1886 if (mr.byte_size() > 0)
1887 1887 _g1_storage.shrink_by(mr.byte_size());
1888 1888 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1889 1889
1890 1890 _g1_committed.set_end(mr.start());
1891 1891 _expansion_regions += num_regions_deleted;
1892 1892
1893 1893 // Tell the cardtable about it.
1894 1894 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1895 1895
1896 1896 // And the offset table as well.
1897 1897 _bot_shared->resize(_g1_committed.word_size());
1898 1898
1899 1899 HeapRegionRemSet::shrink_heap(n_regions());
1900 1900
1901 1901 if (Verbose && PrintGC) {
1902 1902 size_t new_mem_size = _g1_storage.committed_size();
1903 1903 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1904 1904 old_mem_size/K, aligned_shrink_bytes/K,
1905 1905 new_mem_size/K);
1906 1906 }
1907 1907 }
1908 1908
1909 1909 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1910 1910 verify_region_sets_optional();
1911 1911
1912 1912 release_gc_alloc_regions(true /* totally */);
1913 1913 // Instead of tearing down / rebuilding the free lists here, we
1914 1914 // could instead use the remove_all_pending() method on free_list to
1915 1915 // remove only the ones that we need to remove.
1916 1916 tear_down_region_lists(); // We will rebuild them in a moment.
1917 1917 shrink_helper(shrink_bytes);
1918 1918 rebuild_region_lists();
1919 1919
1920 1920 verify_region_sets_optional();
1921 1921 }
1922 1922
1923 1923 // Public methods.
1924 1924
1925 1925 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1926 1926 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1927 1927 #endif // _MSC_VER
1928 1928
1929 1929
1930 1930 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1931 1931 SharedHeap(policy_),
1932 1932 _g1_policy(policy_),
1933 1933 _dirty_card_queue_set(false),
1934 1934 _into_cset_dirty_card_queue_set(false),
1935 1935 _is_alive_closure(this),
1936 1936 _ref_processor(NULL),
1937 1937 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1938 1938 _bot_shared(NULL),
1939 1939 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1940 1940 _evac_failure_scan_stack(NULL) ,
1941 1941 _mark_in_progress(false),
1942 1942 _cg1r(NULL), _summary_bytes_used(0),
1943 1943 _cur_alloc_region(NULL),
1944 1944 _refine_cte_cl(NULL),
1945 1945 _full_collection(false),
1946 1946 _free_list("Master Free List"),
1947 1947 _secondary_free_list("Secondary Free List"),
1948 1948 _humongous_set("Master Humongous Set"),
1949 1949 _free_regions_coming(false),
1950 1950 _young_list(new YoungList(this)),
1951 1951 _gc_time_stamp(0),
1952 1952 _surviving_young_words(NULL),
1953 1953 _full_collections_completed(0),
1954 1954 _in_cset_fast_test(NULL),
1955 1955 _in_cset_fast_test_base(NULL),
1956 1956 _dirty_cards_region_list(NULL) {
1957 1957 _g1h = this; // To catch bugs.
1958 1958 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1959 1959 vm_exit_during_initialization("Failed necessary allocation.");
1960 1960 }
1961 1961
1962 1962 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1963 1963
1964 1964 int n_queues = MAX2((int)ParallelGCThreads, 1);
1965 1965 _task_queues = new RefToScanQueueSet(n_queues);
1966 1966
1967 1967 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1968 1968 assert(n_rem_sets > 0, "Invariant.");
1969 1969
1970 1970 HeapRegionRemSetIterator** iter_arr =
1971 1971 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1972 1972 for (int i = 0; i < n_queues; i++) {
1973 1973 iter_arr[i] = new HeapRegionRemSetIterator();
1974 1974 }
1975 1975 _rem_set_iterator = iter_arr;
1976 1976
1977 1977 for (int i = 0; i < n_queues; i++) {
1978 1978 RefToScanQueue* q = new RefToScanQueue();
1979 1979 q->initialize();
1980 1980 _task_queues->register_queue(i, q);
1981 1981 }
1982 1982
1983 1983 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1984 1984 _gc_alloc_regions[ap] = NULL;
1985 1985 _gc_alloc_region_counts[ap] = 0;
1986 1986 _retained_gc_alloc_regions[ap] = NULL;
1987 1987 // by default, we do not retain a GC alloc region for each ap;
1988 1988 // we'll override this, when appropriate, below
1989 1989 _retain_gc_alloc_region[ap] = false;
1990 1990 }
1991 1991
1992 1992 // We will try to remember the last half-full tenured region we
1993 1993 // allocated to at the end of a collection so that we can re-use it
1994 1994 // during the next collection.
1995 1995 _retain_gc_alloc_region[GCAllocForTenured] = true;
1996 1996
1997 1997 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1998 1998 }
1999 1999
2000 2000 jint G1CollectedHeap::initialize() {
2001 2001 CollectedHeap::pre_initialize();
2002 2002 os::enable_vtime();
2003 2003
2004 2004 // Necessary to satisfy locking discipline assertions.
2005 2005
2006 2006 MutexLocker x(Heap_lock);
2007 2007
2008 2008 // While there are no constraints in the GC code that HeapWordSize
2009 2009 // be any particular value, there are multiple other areas in the
2010 2010 // system which believe this to be true (e.g. oop->object_size in some
2011 2011 // cases incorrectly returns the size in wordSize units rather than
2012 2012 // HeapWordSize).
2013 2013 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2014 2014
2015 2015 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2016 2016 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2017 2017
2018 2018 // Ensure that the sizes are properly aligned.
2019 2019 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2020 2020 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2021 2021
2022 2022 _cg1r = new ConcurrentG1Refine();
2023 2023
2024 2024 // Reserve the maximum.
2025 2025 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
2026 2026 // Includes the perm-gen.
2027 2027
2028 2028 const size_t total_reserved = max_byte_size + pgs->max_size();
2029 2029 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
2030 2030
2031 2031 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
2032 2032 HeapRegion::GrainBytes,
2033 2033 UseLargePages, addr);
2034 2034
2035 2035 if (UseCompressedOops) {
2036 2036 if (addr != NULL && !heap_rs.is_reserved()) {
2037 2037 // Failed to reserve at specified address - the requested memory
2038 2038 // region is taken already, for example, by 'java' launcher.
2039 2039 // Try again to reserver heap higher.
2040 2040 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
2041 2041 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
2042 2042 UseLargePages, addr);
2043 2043 if (addr != NULL && !heap_rs0.is_reserved()) {
2044 2044 // Failed to reserve at specified address again - give up.
2045 2045 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
2046 2046 assert(addr == NULL, "");
2047 2047 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
2048 2048 UseLargePages, addr);
2049 2049 heap_rs = heap_rs1;
2050 2050 } else {
2051 2051 heap_rs = heap_rs0;
2052 2052 }
2053 2053 }
2054 2054 }
2055 2055
2056 2056 if (!heap_rs.is_reserved()) {
2057 2057 vm_exit_during_initialization("Could not reserve enough space for object heap");
2058 2058 return JNI_ENOMEM;
2059 2059 }
2060 2060
2061 2061 // It is important to do this in a way such that concurrent readers can't
2062 2062 // temporarily think somethings in the heap. (I've actually seen this
2063 2063 // happen in asserts: DLD.)
2064 2064 _reserved.set_word_size(0);
2065 2065 _reserved.set_start((HeapWord*)heap_rs.base());
2066 2066 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2067 2067
2068 2068 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
2069 2069
2070 2070 // Create the gen rem set (and barrier set) for the entire reserved region.
2071 2071 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2072 2072 set_barrier_set(rem_set()->bs());
2073 2073 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2074 2074 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2075 2075 } else {
2076 2076 vm_exit_during_initialization("G1 requires a mod ref bs.");
2077 2077 return JNI_ENOMEM;
2078 2078 }
2079 2079
2080 2080 // Also create a G1 rem set.
2081 2081 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2082 2082 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2083 2083 } else {
2084 2084 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2085 2085 return JNI_ENOMEM;
2086 2086 }
2087 2087
2088 2088 // Carve out the G1 part of the heap.
2089 2089
2090 2090 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2091 2091 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2092 2092 g1_rs.size()/HeapWordSize);
2093 2093 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
2094 2094
2095 2095 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2096 2096
2097 2097 _g1_storage.initialize(g1_rs, 0);
2098 2098 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2099 2099 _g1_max_committed = _g1_committed;
2100 2100 _hrs = new HeapRegionSeq(_expansion_regions);
2101 2101 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
2102 2102 guarantee(_cur_alloc_region == NULL, "from constructor");
2103 2103
2104 2104 // 6843694 - ensure that the maximum region index can fit
2105 2105 // in the remembered set structures.
2106 2106 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2107 2107 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2108 2108
2109 2109 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2110 2110 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2111 2111 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
2112 2112 "too many cards per region");
2113 2113
2114 2114 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2115 2115
2116 2116 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2117 2117 heap_word_size(init_byte_size));
2118 2118
2119 2119 _g1h = this;
2120 2120
2121 2121 _in_cset_fast_test_length = max_regions();
2122 2122 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2123 2123
2124 2124 // We're biasing _in_cset_fast_test to avoid subtracting the
2125 2125 // beginning of the heap every time we want to index; basically
2126 2126 // it's the same with what we do with the card table.
2127 2127 _in_cset_fast_test = _in_cset_fast_test_base -
2128 2128 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2129 2129
2130 2130 // Clear the _cset_fast_test bitmap in anticipation of adding
2131 2131 // regions to the incremental collection set for the first
2132 2132 // evacuation pause.
2133 2133 clear_cset_fast_test();
2134 2134
2135 2135 // Create the ConcurrentMark data structure and thread.
2136 2136 // (Must do this late, so that "max_regions" is defined.)
2137 2137 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
2138 2138 _cmThread = _cm->cmThread();
2139 2139
2140 2140 // Initialize the from_card cache structure of HeapRegionRemSet.
2141 2141 HeapRegionRemSet::init_heap(max_regions());
2142 2142
2143 2143 // Now expand into the initial heap size.
2144 2144 if (!expand(init_byte_size)) {
2145 2145 vm_exit_during_initialization("Failed to allocate initial heap.");
2146 2146 return JNI_ENOMEM;
2147 2147 }
2148 2148
2149 2149 // Perform any initialization actions delegated to the policy.
2150 2150 g1_policy()->init();
2151 2151
2152 2152 g1_policy()->note_start_of_mark_thread();
2153 2153
2154 2154 _refine_cte_cl =
2155 2155 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2156 2156 g1_rem_set(),
2157 2157 concurrent_g1_refine());
2158 2158 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2159 2159
2160 2160 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2161 2161 SATB_Q_FL_lock,
2162 2162 G1SATBProcessCompletedThreshold,
2163 2163 Shared_SATB_Q_lock);
2164 2164
2165 2165 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2166 2166 DirtyCardQ_FL_lock,
2167 2167 concurrent_g1_refine()->yellow_zone(),
2168 2168 concurrent_g1_refine()->red_zone(),
2169 2169 Shared_DirtyCardQ_lock);
2170 2170
2171 2171 if (G1DeferredRSUpdate) {
2172 2172 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2173 2173 DirtyCardQ_FL_lock,
2174 2174 -1, // never trigger processing
2175 2175 -1, // no limit on length
2176 2176 Shared_DirtyCardQ_lock,
2177 2177 &JavaThread::dirty_card_queue_set());
2178 2178 }
2179 2179
2180 2180 // Initialize the card queue set used to hold cards containing
2181 2181 // references into the collection set.
2182 2182 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2183 2183 DirtyCardQ_FL_lock,
2184 2184 -1, // never trigger processing
2185 2185 -1, // no limit on length
2186 2186 Shared_DirtyCardQ_lock,
2187 2187 &JavaThread::dirty_card_queue_set());
2188 2188
2189 2189 // In case we're keeping closure specialization stats, initialize those
2190 2190 // counts and that mechanism.
2191 2191 SpecializationStats::clear();
2192 2192
2193 2193 _gc_alloc_region_list = NULL;
2194 2194
2195 2195 // Do later initialization work for concurrent refinement.
2196 2196 _cg1r->init();
2197 2197
2198 2198 return JNI_OK;
2199 2199 }
2200 2200
2201 2201 void G1CollectedHeap::ref_processing_init() {
2202 2202 // Reference processing in G1 currently works as follows:
2203 2203 //
2204 2204 // * There is only one reference processor instance that
2205 2205 // 'spans' the entire heap. It is created by the code
2206 2206 // below.
2207 2207 // * Reference discovery is not enabled during an incremental
2208 2208 // pause (see 6484982).
2209 2209 // * Discoverered refs are not enqueued nor are they processed
2210 2210 // during an incremental pause (see 6484982).
2211 2211 // * Reference discovery is enabled at initial marking.
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2212 2212 // * Reference discovery is disabled and the discovered
2213 2213 // references processed etc during remarking.
2214 2214 // * Reference discovery is MT (see below).
2215 2215 // * Reference discovery requires a barrier (see below).
2216 2216 // * Reference processing is currently not MT (see 6608385).
2217 2217 // * A full GC enables (non-MT) reference discovery and
2218 2218 // processes any discovered references.
2219 2219
2220 2220 SharedHeap::ref_processing_init();
2221 2221 MemRegion mr = reserved_region();
2222 - _ref_processor = ReferenceProcessor::create_ref_processor(
2223 - mr, // span
2224 - false, // Reference discovery is not atomic
2225 - true, // mt_discovery
2226 - &_is_alive_closure, // is alive closure
2227 - // for efficiency
2228 - ParallelGCThreads,
2229 - ParallelRefProcEnabled,
2230 - true); // Setting next fields of discovered
2231 - // lists requires a barrier.
2222 + _ref_processor =
2223 + new ReferenceProcessor(mr, // span
2224 + ParallelRefProcEnabled, // mt processing
2225 + ParallelGCThreads, // degree of mt processing
2226 + true, // mt discovery
2227 + ConcGCThreads, // degree of mt discovery
2228 + false, // Reference discovery is not atomic
2229 + &_is_alive_closure, // is alive closure for efficiency
2230 + true); // Setting next fields of discovered
2231 + // lists requires a barrier.
2232 2232 }
2233 2233
2234 2234 size_t G1CollectedHeap::capacity() const {
2235 2235 return _g1_committed.byte_size();
2236 2236 }
2237 2237
2238 2238 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2239 2239 DirtyCardQueue* into_cset_dcq,
2240 2240 bool concurrent,
2241 2241 int worker_i) {
2242 2242 // Clean cards in the hot card cache
2243 2243 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2244 2244
2245 2245 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2246 2246 int n_completed_buffers = 0;
2247 2247 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2248 2248 n_completed_buffers++;
2249 2249 }
2250 2250 g1_policy()->record_update_rs_processed_buffers(worker_i,
2251 2251 (double) n_completed_buffers);
2252 2252 dcqs.clear_n_completed_buffers();
2253 2253 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2254 2254 }
2255 2255
2256 2256
2257 2257 // Computes the sum of the storage used by the various regions.
2258 2258
2259 2259 size_t G1CollectedHeap::used() const {
2260 2260 assert(Heap_lock->owner() != NULL,
2261 2261 "Should be owned on this thread's behalf.");
2262 2262 size_t result = _summary_bytes_used;
2263 2263 // Read only once in case it is set to NULL concurrently
2264 2264 HeapRegion* hr = _cur_alloc_region;
2265 2265 if (hr != NULL)
2266 2266 result += hr->used();
2267 2267 return result;
2268 2268 }
2269 2269
2270 2270 size_t G1CollectedHeap::used_unlocked() const {
2271 2271 size_t result = _summary_bytes_used;
2272 2272 return result;
2273 2273 }
2274 2274
2275 2275 class SumUsedClosure: public HeapRegionClosure {
2276 2276 size_t _used;
2277 2277 public:
2278 2278 SumUsedClosure() : _used(0) {}
2279 2279 bool doHeapRegion(HeapRegion* r) {
2280 2280 if (!r->continuesHumongous()) {
2281 2281 _used += r->used();
2282 2282 }
2283 2283 return false;
2284 2284 }
2285 2285 size_t result() { return _used; }
2286 2286 };
2287 2287
2288 2288 size_t G1CollectedHeap::recalculate_used() const {
2289 2289 SumUsedClosure blk;
2290 2290 _hrs->iterate(&blk);
2291 2291 return blk.result();
2292 2292 }
2293 2293
2294 2294 #ifndef PRODUCT
2295 2295 class SumUsedRegionsClosure: public HeapRegionClosure {
2296 2296 size_t _num;
2297 2297 public:
2298 2298 SumUsedRegionsClosure() : _num(0) {}
2299 2299 bool doHeapRegion(HeapRegion* r) {
2300 2300 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
2301 2301 _num += 1;
2302 2302 }
2303 2303 return false;
2304 2304 }
2305 2305 size_t result() { return _num; }
2306 2306 };
2307 2307
2308 2308 size_t G1CollectedHeap::recalculate_used_regions() const {
2309 2309 SumUsedRegionsClosure blk;
2310 2310 _hrs->iterate(&blk);
2311 2311 return blk.result();
2312 2312 }
2313 2313 #endif // PRODUCT
2314 2314
2315 2315 size_t G1CollectedHeap::unsafe_max_alloc() {
2316 2316 if (free_regions() > 0) return HeapRegion::GrainBytes;
2317 2317 // otherwise, is there space in the current allocation region?
2318 2318
2319 2319 // We need to store the current allocation region in a local variable
2320 2320 // here. The problem is that this method doesn't take any locks and
2321 2321 // there may be other threads which overwrite the current allocation
2322 2322 // region field. attempt_allocation(), for example, sets it to NULL
2323 2323 // and this can happen *after* the NULL check here but before the call
2324 2324 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2325 2325 // to be a problem in the optimized build, since the two loads of the
2326 2326 // current allocation region field are optimized away.
2327 2327 HeapRegion* car = _cur_alloc_region;
2328 2328
2329 2329 // FIXME: should iterate over all regions?
2330 2330 if (car == NULL) {
2331 2331 return 0;
2332 2332 }
2333 2333 return car->free();
2334 2334 }
2335 2335
2336 2336 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2337 2337 return
2338 2338 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2339 2339 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2340 2340 }
2341 2341
2342 2342 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2343 2343 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2344 2344
2345 2345 // We assume that if concurrent == true, then the caller is a
2346 2346 // concurrent thread that was joined the Suspendible Thread
2347 2347 // Set. If there's ever a cheap way to check this, we should add an
2348 2348 // assert here.
2349 2349
2350 2350 // We have already incremented _total_full_collections at the start
2351 2351 // of the GC, so total_full_collections() represents how many full
2352 2352 // collections have been started.
2353 2353 unsigned int full_collections_started = total_full_collections();
2354 2354
2355 2355 // Given that this method is called at the end of a Full GC or of a
2356 2356 // concurrent cycle, and those can be nested (i.e., a Full GC can
2357 2357 // interrupt a concurrent cycle), the number of full collections
2358 2358 // completed should be either one (in the case where there was no
2359 2359 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2360 2360 // behind the number of full collections started.
2361 2361
2362 2362 // This is the case for the inner caller, i.e. a Full GC.
2363 2363 assert(concurrent ||
2364 2364 (full_collections_started == _full_collections_completed + 1) ||
2365 2365 (full_collections_started == _full_collections_completed + 2),
2366 2366 err_msg("for inner caller (Full GC): full_collections_started = %u "
2367 2367 "is inconsistent with _full_collections_completed = %u",
2368 2368 full_collections_started, _full_collections_completed));
2369 2369
2370 2370 // This is the case for the outer caller, i.e. the concurrent cycle.
2371 2371 assert(!concurrent ||
2372 2372 (full_collections_started == _full_collections_completed + 1),
2373 2373 err_msg("for outer caller (concurrent cycle): "
2374 2374 "full_collections_started = %u "
2375 2375 "is inconsistent with _full_collections_completed = %u",
2376 2376 full_collections_started, _full_collections_completed));
2377 2377
2378 2378 _full_collections_completed += 1;
2379 2379
2380 2380 // We need to clear the "in_progress" flag in the CM thread before
2381 2381 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2382 2382 // is set) so that if a waiter requests another System.gc() it doesn't
2383 2383 // incorrectly see that a marking cyle is still in progress.
2384 2384 if (concurrent) {
2385 2385 _cmThread->clear_in_progress();
2386 2386 }
2387 2387
2388 2388 // This notify_all() will ensure that a thread that called
2389 2389 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2390 2390 // and it's waiting for a full GC to finish will be woken up. It is
2391 2391 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2392 2392 FullGCCount_lock->notify_all();
2393 2393 }
2394 2394
2395 2395 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2396 2396 assert_at_safepoint(true /* should_be_vm_thread */);
2397 2397 GCCauseSetter gcs(this, cause);
2398 2398 switch (cause) {
2399 2399 case GCCause::_heap_inspection:
2400 2400 case GCCause::_heap_dump: {
2401 2401 HandleMark hm;
2402 2402 do_full_collection(false); // don't clear all soft refs
2403 2403 break;
2404 2404 }
2405 2405 default: // XXX FIX ME
2406 2406 ShouldNotReachHere(); // Unexpected use of this function
2407 2407 }
2408 2408 }
2409 2409
2410 2410 void G1CollectedHeap::collect(GCCause::Cause cause) {
2411 2411 // The caller doesn't have the Heap_lock
2412 2412 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2413 2413
2414 2414 unsigned int gc_count_before;
2415 2415 unsigned int full_gc_count_before;
2416 2416 {
2417 2417 MutexLocker ml(Heap_lock);
2418 2418
2419 2419 // Read the GC count while holding the Heap_lock
2420 2420 gc_count_before = SharedHeap::heap()->total_collections();
2421 2421 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2422 2422 }
2423 2423
2424 2424 if (should_do_concurrent_full_gc(cause)) {
2425 2425 // Schedule an initial-mark evacuation pause that will start a
2426 2426 // concurrent cycle. We're setting word_size to 0 which means that
2427 2427 // we are not requesting a post-GC allocation.
2428 2428 VM_G1IncCollectionPause op(gc_count_before,
2429 2429 0, /* word_size */
2430 2430 true, /* should_initiate_conc_mark */
2431 2431 g1_policy()->max_pause_time_ms(),
2432 2432 cause);
2433 2433 VMThread::execute(&op);
2434 2434 } else {
2435 2435 if (cause == GCCause::_gc_locker
2436 2436 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2437 2437
2438 2438 // Schedule a standard evacuation pause. We're setting word_size
2439 2439 // to 0 which means that we are not requesting a post-GC allocation.
2440 2440 VM_G1IncCollectionPause op(gc_count_before,
2441 2441 0, /* word_size */
2442 2442 false, /* should_initiate_conc_mark */
2443 2443 g1_policy()->max_pause_time_ms(),
2444 2444 cause);
2445 2445 VMThread::execute(&op);
2446 2446 } else {
2447 2447 // Schedule a Full GC.
2448 2448 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2449 2449 VMThread::execute(&op);
2450 2450 }
2451 2451 }
2452 2452 }
2453 2453
2454 2454 bool G1CollectedHeap::is_in(const void* p) const {
2455 2455 if (_g1_committed.contains(p)) {
2456 2456 HeapRegion* hr = _hrs->addr_to_region(p);
2457 2457 return hr->is_in(p);
2458 2458 } else {
2459 2459 return _perm_gen->as_gen()->is_in(p);
2460 2460 }
2461 2461 }
2462 2462
2463 2463 // Iteration functions.
2464 2464
2465 2465 // Iterates an OopClosure over all ref-containing fields of objects
2466 2466 // within a HeapRegion.
2467 2467
2468 2468 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2469 2469 MemRegion _mr;
2470 2470 OopClosure* _cl;
2471 2471 public:
2472 2472 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2473 2473 : _mr(mr), _cl(cl) {}
2474 2474 bool doHeapRegion(HeapRegion* r) {
2475 2475 if (! r->continuesHumongous()) {
2476 2476 r->oop_iterate(_cl);
2477 2477 }
2478 2478 return false;
2479 2479 }
2480 2480 };
2481 2481
2482 2482 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2483 2483 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2484 2484 _hrs->iterate(&blk);
2485 2485 if (do_perm) {
2486 2486 perm_gen()->oop_iterate(cl);
2487 2487 }
2488 2488 }
2489 2489
2490 2490 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2491 2491 IterateOopClosureRegionClosure blk(mr, cl);
2492 2492 _hrs->iterate(&blk);
2493 2493 if (do_perm) {
2494 2494 perm_gen()->oop_iterate(cl);
2495 2495 }
2496 2496 }
2497 2497
2498 2498 // Iterates an ObjectClosure over all objects within a HeapRegion.
2499 2499
2500 2500 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2501 2501 ObjectClosure* _cl;
2502 2502 public:
2503 2503 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2504 2504 bool doHeapRegion(HeapRegion* r) {
2505 2505 if (! r->continuesHumongous()) {
2506 2506 r->object_iterate(_cl);
2507 2507 }
2508 2508 return false;
2509 2509 }
2510 2510 };
2511 2511
2512 2512 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2513 2513 IterateObjectClosureRegionClosure blk(cl);
2514 2514 _hrs->iterate(&blk);
2515 2515 if (do_perm) {
2516 2516 perm_gen()->object_iterate(cl);
2517 2517 }
2518 2518 }
2519 2519
2520 2520 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2521 2521 // FIXME: is this right?
2522 2522 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2523 2523 }
2524 2524
2525 2525 // Calls a SpaceClosure on a HeapRegion.
2526 2526
2527 2527 class SpaceClosureRegionClosure: public HeapRegionClosure {
2528 2528 SpaceClosure* _cl;
2529 2529 public:
2530 2530 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2531 2531 bool doHeapRegion(HeapRegion* r) {
2532 2532 _cl->do_space(r);
2533 2533 return false;
2534 2534 }
2535 2535 };
2536 2536
2537 2537 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2538 2538 SpaceClosureRegionClosure blk(cl);
2539 2539 _hrs->iterate(&blk);
2540 2540 }
2541 2541
2542 2542 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
2543 2543 _hrs->iterate(cl);
2544 2544 }
2545 2545
2546 2546 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2547 2547 HeapRegionClosure* cl) {
2548 2548 _hrs->iterate_from(r, cl);
2549 2549 }
2550 2550
2551 2551 void
2552 2552 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
2553 2553 _hrs->iterate_from(idx, cl);
2554 2554 }
2555 2555
2556 2556 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
2557 2557
2558 2558 void
2559 2559 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2560 2560 int worker,
2561 2561 jint claim_value) {
2562 2562 const size_t regions = n_regions();
2563 2563 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2564 2564 // try to spread out the starting points of the workers
2565 2565 const size_t start_index = regions / worker_num * (size_t) worker;
2566 2566
2567 2567 // each worker will actually look at all regions
2568 2568 for (size_t count = 0; count < regions; ++count) {
2569 2569 const size_t index = (start_index + count) % regions;
2570 2570 assert(0 <= index && index < regions, "sanity");
2571 2571 HeapRegion* r = region_at(index);
2572 2572 // we'll ignore "continues humongous" regions (we'll process them
2573 2573 // when we come across their corresponding "start humongous"
2574 2574 // region) and regions already claimed
2575 2575 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2576 2576 continue;
2577 2577 }
2578 2578 // OK, try to claim it
2579 2579 if (r->claimHeapRegion(claim_value)) {
2580 2580 // success!
2581 2581 assert(!r->continuesHumongous(), "sanity");
2582 2582 if (r->startsHumongous()) {
2583 2583 // If the region is "starts humongous" we'll iterate over its
2584 2584 // "continues humongous" first; in fact we'll do them
2585 2585 // first. The order is important. In on case, calling the
2586 2586 // closure on the "starts humongous" region might de-allocate
2587 2587 // and clear all its "continues humongous" regions and, as a
2588 2588 // result, we might end up processing them twice. So, we'll do
2589 2589 // them first (notice: most closures will ignore them anyway) and
2590 2590 // then we'll do the "starts humongous" region.
2591 2591 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2592 2592 HeapRegion* chr = region_at(ch_index);
2593 2593
2594 2594 // if the region has already been claimed or it's not
2595 2595 // "continues humongous" we're done
2596 2596 if (chr->claim_value() == claim_value ||
2597 2597 !chr->continuesHumongous()) {
2598 2598 break;
2599 2599 }
2600 2600
2601 2601 // Noone should have claimed it directly. We can given
2602 2602 // that we claimed its "starts humongous" region.
2603 2603 assert(chr->claim_value() != claim_value, "sanity");
2604 2604 assert(chr->humongous_start_region() == r, "sanity");
2605 2605
2606 2606 if (chr->claimHeapRegion(claim_value)) {
2607 2607 // we should always be able to claim it; noone else should
2608 2608 // be trying to claim this region
2609 2609
2610 2610 bool res2 = cl->doHeapRegion(chr);
2611 2611 assert(!res2, "Should not abort");
2612 2612
2613 2613 // Right now, this holds (i.e., no closure that actually
2614 2614 // does something with "continues humongous" regions
2615 2615 // clears them). We might have to weaken it in the future,
2616 2616 // but let's leave these two asserts here for extra safety.
2617 2617 assert(chr->continuesHumongous(), "should still be the case");
2618 2618 assert(chr->humongous_start_region() == r, "sanity");
2619 2619 } else {
2620 2620 guarantee(false, "we should not reach here");
2621 2621 }
2622 2622 }
2623 2623 }
2624 2624
2625 2625 assert(!r->continuesHumongous(), "sanity");
2626 2626 bool res = cl->doHeapRegion(r);
2627 2627 assert(!res, "Should not abort");
2628 2628 }
2629 2629 }
2630 2630 }
2631 2631
2632 2632 class ResetClaimValuesClosure: public HeapRegionClosure {
2633 2633 public:
2634 2634 bool doHeapRegion(HeapRegion* r) {
2635 2635 r->set_claim_value(HeapRegion::InitialClaimValue);
2636 2636 return false;
2637 2637 }
2638 2638 };
2639 2639
2640 2640 void
2641 2641 G1CollectedHeap::reset_heap_region_claim_values() {
2642 2642 ResetClaimValuesClosure blk;
2643 2643 heap_region_iterate(&blk);
2644 2644 }
2645 2645
2646 2646 #ifdef ASSERT
2647 2647 // This checks whether all regions in the heap have the correct claim
2648 2648 // value. I also piggy-backed on this a check to ensure that the
2649 2649 // humongous_start_region() information on "continues humongous"
2650 2650 // regions is correct.
2651 2651
2652 2652 class CheckClaimValuesClosure : public HeapRegionClosure {
2653 2653 private:
2654 2654 jint _claim_value;
2655 2655 size_t _failures;
2656 2656 HeapRegion* _sh_region;
2657 2657 public:
2658 2658 CheckClaimValuesClosure(jint claim_value) :
2659 2659 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2660 2660 bool doHeapRegion(HeapRegion* r) {
2661 2661 if (r->claim_value() != _claim_value) {
2662 2662 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2663 2663 "claim value = %d, should be %d",
2664 2664 r->bottom(), r->end(), r->claim_value(),
2665 2665 _claim_value);
2666 2666 ++_failures;
2667 2667 }
2668 2668 if (!r->isHumongous()) {
2669 2669 _sh_region = NULL;
2670 2670 } else if (r->startsHumongous()) {
2671 2671 _sh_region = r;
2672 2672 } else if (r->continuesHumongous()) {
2673 2673 if (r->humongous_start_region() != _sh_region) {
2674 2674 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2675 2675 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2676 2676 r->bottom(), r->end(),
2677 2677 r->humongous_start_region(),
2678 2678 _sh_region);
2679 2679 ++_failures;
2680 2680 }
2681 2681 }
2682 2682 return false;
2683 2683 }
2684 2684 size_t failures() {
2685 2685 return _failures;
2686 2686 }
2687 2687 };
2688 2688
2689 2689 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2690 2690 CheckClaimValuesClosure cl(claim_value);
2691 2691 heap_region_iterate(&cl);
2692 2692 return cl.failures() == 0;
2693 2693 }
2694 2694 #endif // ASSERT
2695 2695
2696 2696 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2697 2697 HeapRegion* r = g1_policy()->collection_set();
2698 2698 while (r != NULL) {
2699 2699 HeapRegion* next = r->next_in_collection_set();
2700 2700 if (cl->doHeapRegion(r)) {
2701 2701 cl->incomplete();
2702 2702 return;
2703 2703 }
2704 2704 r = next;
2705 2705 }
2706 2706 }
2707 2707
2708 2708 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2709 2709 HeapRegionClosure *cl) {
2710 2710 if (r == NULL) {
2711 2711 // The CSet is empty so there's nothing to do.
2712 2712 return;
2713 2713 }
2714 2714
2715 2715 assert(r->in_collection_set(),
2716 2716 "Start region must be a member of the collection set.");
2717 2717 HeapRegion* cur = r;
2718 2718 while (cur != NULL) {
2719 2719 HeapRegion* next = cur->next_in_collection_set();
2720 2720 if (cl->doHeapRegion(cur) && false) {
2721 2721 cl->incomplete();
2722 2722 return;
2723 2723 }
2724 2724 cur = next;
2725 2725 }
2726 2726 cur = g1_policy()->collection_set();
2727 2727 while (cur != r) {
2728 2728 HeapRegion* next = cur->next_in_collection_set();
2729 2729 if (cl->doHeapRegion(cur) && false) {
2730 2730 cl->incomplete();
2731 2731 return;
2732 2732 }
2733 2733 cur = next;
2734 2734 }
2735 2735 }
2736 2736
2737 2737 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2738 2738 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2739 2739 }
2740 2740
2741 2741
2742 2742 Space* G1CollectedHeap::space_containing(const void* addr) const {
2743 2743 Space* res = heap_region_containing(addr);
2744 2744 if (res == NULL)
2745 2745 res = perm_gen()->space_containing(addr);
2746 2746 return res;
2747 2747 }
2748 2748
2749 2749 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2750 2750 Space* sp = space_containing(addr);
2751 2751 if (sp != NULL) {
2752 2752 return sp->block_start(addr);
2753 2753 }
2754 2754 return NULL;
2755 2755 }
2756 2756
2757 2757 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2758 2758 Space* sp = space_containing(addr);
2759 2759 assert(sp != NULL, "block_size of address outside of heap");
2760 2760 return sp->block_size(addr);
2761 2761 }
2762 2762
2763 2763 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2764 2764 Space* sp = space_containing(addr);
2765 2765 return sp->block_is_obj(addr);
2766 2766 }
2767 2767
2768 2768 bool G1CollectedHeap::supports_tlab_allocation() const {
2769 2769 return true;
2770 2770 }
2771 2771
2772 2772 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2773 2773 return HeapRegion::GrainBytes;
2774 2774 }
2775 2775
2776 2776 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2777 2777 // Return the remaining space in the cur alloc region, but not less than
2778 2778 // the min TLAB size.
2779 2779
2780 2780 // Also, this value can be at most the humongous object threshold,
2781 2781 // since we can't allow tlabs to grow big enough to accomodate
2782 2782 // humongous objects.
2783 2783
2784 2784 // We need to store the cur alloc region locally, since it might change
2785 2785 // between when we test for NULL and when we use it later.
2786 2786 ContiguousSpace* cur_alloc_space = _cur_alloc_region;
2787 2787 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2788 2788
2789 2789 if (cur_alloc_space == NULL) {
2790 2790 return max_tlab_size;
2791 2791 } else {
2792 2792 return MIN2(MAX2(cur_alloc_space->free(), (size_t)MinTLABSize),
2793 2793 max_tlab_size);
2794 2794 }
2795 2795 }
2796 2796
2797 2797 size_t G1CollectedHeap::large_typearray_limit() {
2798 2798 // FIXME
2799 2799 return HeapRegion::GrainBytes/HeapWordSize;
2800 2800 }
2801 2801
2802 2802 size_t G1CollectedHeap::max_capacity() const {
2803 2803 return _g1_reserved.byte_size();
2804 2804 }
2805 2805
2806 2806 jlong G1CollectedHeap::millis_since_last_gc() {
2807 2807 // assert(false, "NYI");
2808 2808 return 0;
2809 2809 }
2810 2810
2811 2811 void G1CollectedHeap::prepare_for_verify() {
2812 2812 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2813 2813 ensure_parsability(false);
2814 2814 }
2815 2815 g1_rem_set()->prepare_for_verify();
2816 2816 }
2817 2817
2818 2818 class VerifyLivenessOopClosure: public OopClosure {
2819 2819 G1CollectedHeap* g1h;
2820 2820 public:
2821 2821 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2822 2822 g1h = _g1h;
2823 2823 }
2824 2824 void do_oop(narrowOop *p) { do_oop_work(p); }
2825 2825 void do_oop( oop *p) { do_oop_work(p); }
2826 2826
2827 2827 template <class T> void do_oop_work(T *p) {
2828 2828 oop obj = oopDesc::load_decode_heap_oop(p);
2829 2829 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2830 2830 "Dead object referenced by a not dead object");
2831 2831 }
2832 2832 };
2833 2833
2834 2834 class VerifyObjsInRegionClosure: public ObjectClosure {
2835 2835 private:
2836 2836 G1CollectedHeap* _g1h;
2837 2837 size_t _live_bytes;
2838 2838 HeapRegion *_hr;
2839 2839 bool _use_prev_marking;
2840 2840 public:
2841 2841 // use_prev_marking == true -> use "prev" marking information,
2842 2842 // use_prev_marking == false -> use "next" marking information
2843 2843 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2844 2844 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2845 2845 _g1h = G1CollectedHeap::heap();
2846 2846 }
2847 2847 void do_object(oop o) {
2848 2848 VerifyLivenessOopClosure isLive(_g1h);
2849 2849 assert(o != NULL, "Huh?");
2850 2850 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2851 2851 o->oop_iterate(&isLive);
2852 2852 if (!_hr->obj_allocated_since_prev_marking(o)) {
2853 2853 size_t obj_size = o->size(); // Make sure we don't overflow
2854 2854 _live_bytes += (obj_size * HeapWordSize);
2855 2855 }
2856 2856 }
2857 2857 }
2858 2858 size_t live_bytes() { return _live_bytes; }
2859 2859 };
2860 2860
2861 2861 class PrintObjsInRegionClosure : public ObjectClosure {
2862 2862 HeapRegion *_hr;
2863 2863 G1CollectedHeap *_g1;
2864 2864 public:
2865 2865 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2866 2866 _g1 = G1CollectedHeap::heap();
2867 2867 };
2868 2868
2869 2869 void do_object(oop o) {
2870 2870 if (o != NULL) {
2871 2871 HeapWord *start = (HeapWord *) o;
2872 2872 size_t word_sz = o->size();
2873 2873 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2874 2874 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2875 2875 (void*) o, word_sz,
2876 2876 _g1->isMarkedPrev(o),
2877 2877 _g1->isMarkedNext(o),
2878 2878 _hr->obj_allocated_since_prev_marking(o));
2879 2879 HeapWord *end = start + word_sz;
2880 2880 HeapWord *cur;
2881 2881 int *val;
2882 2882 for (cur = start; cur < end; cur++) {
2883 2883 val = (int *) cur;
2884 2884 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2885 2885 }
2886 2886 }
2887 2887 }
2888 2888 };
2889 2889
2890 2890 class VerifyRegionClosure: public HeapRegionClosure {
2891 2891 private:
2892 2892 bool _allow_dirty;
2893 2893 bool _par;
2894 2894 bool _use_prev_marking;
2895 2895 bool _failures;
2896 2896 public:
2897 2897 // use_prev_marking == true -> use "prev" marking information,
2898 2898 // use_prev_marking == false -> use "next" marking information
2899 2899 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2900 2900 : _allow_dirty(allow_dirty),
2901 2901 _par(par),
2902 2902 _use_prev_marking(use_prev_marking),
2903 2903 _failures(false) {}
2904 2904
2905 2905 bool failures() {
2906 2906 return _failures;
2907 2907 }
2908 2908
2909 2909 bool doHeapRegion(HeapRegion* r) {
2910 2910 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2911 2911 "Should be unclaimed at verify points.");
2912 2912 if (!r->continuesHumongous()) {
2913 2913 bool failures = false;
2914 2914 r->verify(_allow_dirty, _use_prev_marking, &failures);
2915 2915 if (failures) {
2916 2916 _failures = true;
2917 2917 } else {
2918 2918 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2919 2919 r->object_iterate(¬_dead_yet_cl);
2920 2920 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2921 2921 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2922 2922 "max_live_bytes "SIZE_FORMAT" "
2923 2923 "< calculated "SIZE_FORMAT,
2924 2924 r->bottom(), r->end(),
2925 2925 r->max_live_bytes(),
2926 2926 not_dead_yet_cl.live_bytes());
2927 2927 _failures = true;
2928 2928 }
2929 2929 }
2930 2930 }
2931 2931 return false; // stop the region iteration if we hit a failure
2932 2932 }
2933 2933 };
2934 2934
2935 2935 class VerifyRootsClosure: public OopsInGenClosure {
2936 2936 private:
2937 2937 G1CollectedHeap* _g1h;
2938 2938 bool _use_prev_marking;
2939 2939 bool _failures;
2940 2940 public:
2941 2941 // use_prev_marking == true -> use "prev" marking information,
2942 2942 // use_prev_marking == false -> use "next" marking information
2943 2943 VerifyRootsClosure(bool use_prev_marking) :
2944 2944 _g1h(G1CollectedHeap::heap()),
2945 2945 _use_prev_marking(use_prev_marking),
2946 2946 _failures(false) { }
2947 2947
2948 2948 bool failures() { return _failures; }
2949 2949
2950 2950 template <class T> void do_oop_nv(T* p) {
2951 2951 T heap_oop = oopDesc::load_heap_oop(p);
2952 2952 if (!oopDesc::is_null(heap_oop)) {
2953 2953 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2954 2954 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2955 2955 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2956 2956 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2957 2957 obj->print_on(gclog_or_tty);
2958 2958 _failures = true;
2959 2959 }
2960 2960 }
2961 2961 }
2962 2962
2963 2963 void do_oop(oop* p) { do_oop_nv(p); }
2964 2964 void do_oop(narrowOop* p) { do_oop_nv(p); }
2965 2965 };
2966 2966
2967 2967 // This is the task used for parallel heap verification.
2968 2968
2969 2969 class G1ParVerifyTask: public AbstractGangTask {
2970 2970 private:
2971 2971 G1CollectedHeap* _g1h;
2972 2972 bool _allow_dirty;
2973 2973 bool _use_prev_marking;
2974 2974 bool _failures;
2975 2975
2976 2976 public:
2977 2977 // use_prev_marking == true -> use "prev" marking information,
2978 2978 // use_prev_marking == false -> use "next" marking information
2979 2979 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2980 2980 bool use_prev_marking) :
2981 2981 AbstractGangTask("Parallel verify task"),
2982 2982 _g1h(g1h),
2983 2983 _allow_dirty(allow_dirty),
2984 2984 _use_prev_marking(use_prev_marking),
2985 2985 _failures(false) { }
2986 2986
2987 2987 bool failures() {
2988 2988 return _failures;
2989 2989 }
2990 2990
2991 2991 void work(int worker_i) {
2992 2992 HandleMark hm;
2993 2993 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2994 2994 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2995 2995 HeapRegion::ParVerifyClaimValue);
2996 2996 if (blk.failures()) {
2997 2997 _failures = true;
2998 2998 }
2999 2999 }
3000 3000 };
3001 3001
3002 3002 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
3003 3003 verify(allow_dirty, silent, /* use_prev_marking */ true);
3004 3004 }
3005 3005
3006 3006 void G1CollectedHeap::verify(bool allow_dirty,
3007 3007 bool silent,
3008 3008 bool use_prev_marking) {
3009 3009 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3010 3010 if (!silent) { gclog_or_tty->print("roots "); }
3011 3011 VerifyRootsClosure rootsCl(use_prev_marking);
3012 3012 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3013 3013 process_strong_roots(true, // activate StrongRootsScope
3014 3014 false,
3015 3015 SharedHeap::SO_AllClasses,
3016 3016 &rootsCl,
3017 3017 &blobsCl,
3018 3018 &rootsCl);
3019 3019 bool failures = rootsCl.failures();
3020 3020 rem_set()->invalidate(perm_gen()->used_region(), false);
3021 3021 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3022 3022 verify_region_sets();
3023 3023 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3024 3024 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3025 3025 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3026 3026 "sanity check");
3027 3027
3028 3028 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
3029 3029 int n_workers = workers()->total_workers();
3030 3030 set_par_threads(n_workers);
3031 3031 workers()->run_task(&task);
3032 3032 set_par_threads(0);
3033 3033 if (task.failures()) {
3034 3034 failures = true;
3035 3035 }
3036 3036
3037 3037 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3038 3038 "sanity check");
3039 3039
3040 3040 reset_heap_region_claim_values();
3041 3041
3042 3042 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3043 3043 "sanity check");
3044 3044 } else {
3045 3045 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
3046 3046 _hrs->iterate(&blk);
3047 3047 if (blk.failures()) {
3048 3048 failures = true;
3049 3049 }
3050 3050 }
3051 3051 if (!silent) gclog_or_tty->print("RemSet ");
3052 3052 rem_set()->verify();
3053 3053
3054 3054 if (failures) {
3055 3055 gclog_or_tty->print_cr("Heap:");
3056 3056 print_on(gclog_or_tty, true /* extended */);
3057 3057 gclog_or_tty->print_cr("");
3058 3058 #ifndef PRODUCT
3059 3059 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3060 3060 concurrent_mark()->print_reachable("at-verification-failure",
3061 3061 use_prev_marking, false /* all */);
3062 3062 }
3063 3063 #endif
3064 3064 gclog_or_tty->flush();
3065 3065 }
3066 3066 guarantee(!failures, "there should not have been any failures");
3067 3067 } else {
3068 3068 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3069 3069 }
3070 3070 }
3071 3071
3072 3072 class PrintRegionClosure: public HeapRegionClosure {
3073 3073 outputStream* _st;
3074 3074 public:
3075 3075 PrintRegionClosure(outputStream* st) : _st(st) {}
3076 3076 bool doHeapRegion(HeapRegion* r) {
3077 3077 r->print_on(_st);
3078 3078 return false;
3079 3079 }
3080 3080 };
3081 3081
3082 3082 void G1CollectedHeap::print() const { print_on(tty); }
3083 3083
3084 3084 void G1CollectedHeap::print_on(outputStream* st) const {
3085 3085 print_on(st, PrintHeapAtGCExtended);
3086 3086 }
3087 3087
3088 3088 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
3089 3089 st->print(" %-20s", "garbage-first heap");
3090 3090 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3091 3091 capacity()/K, used_unlocked()/K);
3092 3092 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3093 3093 _g1_storage.low_boundary(),
3094 3094 _g1_storage.high(),
3095 3095 _g1_storage.high_boundary());
3096 3096 st->cr();
3097 3097 st->print(" region size " SIZE_FORMAT "K, ",
3098 3098 HeapRegion::GrainBytes/K);
3099 3099 size_t young_regions = _young_list->length();
3100 3100 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3101 3101 young_regions, young_regions * HeapRegion::GrainBytes / K);
3102 3102 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3103 3103 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3104 3104 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3105 3105 st->cr();
3106 3106 perm()->as_gen()->print_on(st);
3107 3107 if (extended) {
3108 3108 st->cr();
3109 3109 print_on_extended(st);
3110 3110 }
3111 3111 }
3112 3112
3113 3113 void G1CollectedHeap::print_on_extended(outputStream* st) const {
3114 3114 PrintRegionClosure blk(st);
3115 3115 _hrs->iterate(&blk);
3116 3116 }
3117 3117
3118 3118 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3119 3119 if (G1CollectedHeap::use_parallel_gc_threads()) {
3120 3120 workers()->print_worker_threads_on(st);
3121 3121 }
3122 3122 _cmThread->print_on(st);
3123 3123 st->cr();
3124 3124 _cm->print_worker_threads_on(st);
3125 3125 _cg1r->print_worker_threads_on(st);
3126 3126 st->cr();
3127 3127 }
3128 3128
3129 3129 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3130 3130 if (G1CollectedHeap::use_parallel_gc_threads()) {
3131 3131 workers()->threads_do(tc);
3132 3132 }
3133 3133 tc->do_thread(_cmThread);
3134 3134 _cg1r->threads_do(tc);
3135 3135 }
3136 3136
3137 3137 void G1CollectedHeap::print_tracing_info() const {
3138 3138 // We'll overload this to mean "trace GC pause statistics."
3139 3139 if (TraceGen0Time || TraceGen1Time) {
3140 3140 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3141 3141 // to that.
3142 3142 g1_policy()->print_tracing_info();
3143 3143 }
3144 3144 if (G1SummarizeRSetStats) {
3145 3145 g1_rem_set()->print_summary_info();
3146 3146 }
3147 3147 if (G1SummarizeConcMark) {
3148 3148 concurrent_mark()->print_summary_info();
3149 3149 }
3150 3150 g1_policy()->print_yg_surv_rate_info();
3151 3151 SpecializationStats::print();
3152 3152 }
3153 3153
3154 3154 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
3155 3155 HeapRegion* hr = heap_region_containing(addr);
3156 3156 if (hr == NULL) {
3157 3157 return 0;
3158 3158 } else {
3159 3159 return 1;
3160 3160 }
3161 3161 }
3162 3162
3163 3163 G1CollectedHeap* G1CollectedHeap::heap() {
3164 3164 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3165 3165 "not a garbage-first heap");
3166 3166 return _g1h;
3167 3167 }
3168 3168
3169 3169 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3170 3170 // always_do_update_barrier = false;
3171 3171 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3172 3172 // Call allocation profiler
3173 3173 AllocationProfiler::iterate_since_last_gc();
3174 3174 // Fill TLAB's and such
3175 3175 ensure_parsability(true);
3176 3176 }
3177 3177
3178 3178 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3179 3179 // FIXME: what is this about?
3180 3180 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3181 3181 // is set.
3182 3182 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3183 3183 "derived pointer present"));
3184 3184 // always_do_update_barrier = true;
3185 3185 }
3186 3186
3187 3187 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3188 3188 unsigned int gc_count_before,
3189 3189 bool* succeeded) {
3190 3190 assert_heap_not_locked_and_not_at_safepoint();
3191 3191 g1_policy()->record_stop_world_start();
3192 3192 VM_G1IncCollectionPause op(gc_count_before,
3193 3193 word_size,
3194 3194 false, /* should_initiate_conc_mark */
3195 3195 g1_policy()->max_pause_time_ms(),
3196 3196 GCCause::_g1_inc_collection_pause);
3197 3197 VMThread::execute(&op);
3198 3198
3199 3199 HeapWord* result = op.result();
3200 3200 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3201 3201 assert(result == NULL || ret_succeeded,
3202 3202 "the result should be NULL if the VM did not succeed");
3203 3203 *succeeded = ret_succeeded;
3204 3204
3205 3205 assert_heap_not_locked();
3206 3206 return result;
3207 3207 }
3208 3208
3209 3209 void
3210 3210 G1CollectedHeap::doConcurrentMark() {
3211 3211 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3212 3212 if (!_cmThread->in_progress()) {
3213 3213 _cmThread->set_started();
3214 3214 CGC_lock->notify();
3215 3215 }
3216 3216 }
3217 3217
3218 3218 class VerifyMarkedObjsClosure: public ObjectClosure {
3219 3219 G1CollectedHeap* _g1h;
3220 3220 public:
3221 3221 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
3222 3222 void do_object(oop obj) {
3223 3223 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
3224 3224 "markandsweep mark should agree with concurrent deadness");
3225 3225 }
3226 3226 };
3227 3227
3228 3228 void
3229 3229 G1CollectedHeap::checkConcurrentMark() {
3230 3230 VerifyMarkedObjsClosure verifycl(this);
3231 3231 // MutexLockerEx x(getMarkBitMapLock(),
3232 3232 // Mutex::_no_safepoint_check_flag);
3233 3233 object_iterate(&verifycl, false);
3234 3234 }
3235 3235
3236 3236 void G1CollectedHeap::do_sync_mark() {
3237 3237 _cm->checkpointRootsInitial();
3238 3238 _cm->markFromRoots();
3239 3239 _cm->checkpointRootsFinal(false);
3240 3240 }
3241 3241
3242 3242 // <NEW PREDICTION>
3243 3243
3244 3244 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3245 3245 bool young) {
3246 3246 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3247 3247 }
3248 3248
3249 3249 void G1CollectedHeap::check_if_region_is_too_expensive(double
3250 3250 predicted_time_ms) {
3251 3251 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3252 3252 }
3253 3253
3254 3254 size_t G1CollectedHeap::pending_card_num() {
3255 3255 size_t extra_cards = 0;
3256 3256 JavaThread *curr = Threads::first();
3257 3257 while (curr != NULL) {
3258 3258 DirtyCardQueue& dcq = curr->dirty_card_queue();
3259 3259 extra_cards += dcq.size();
3260 3260 curr = curr->next();
3261 3261 }
3262 3262 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3263 3263 size_t buffer_size = dcqs.buffer_size();
3264 3264 size_t buffer_num = dcqs.completed_buffers_num();
3265 3265 return buffer_size * buffer_num + extra_cards;
3266 3266 }
3267 3267
3268 3268 size_t G1CollectedHeap::max_pending_card_num() {
3269 3269 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3270 3270 size_t buffer_size = dcqs.buffer_size();
3271 3271 size_t buffer_num = dcqs.completed_buffers_num();
3272 3272 int thread_num = Threads::number_of_threads();
3273 3273 return (buffer_num + thread_num) * buffer_size;
3274 3274 }
3275 3275
3276 3276 size_t G1CollectedHeap::cards_scanned() {
3277 3277 return g1_rem_set()->cardsScanned();
3278 3278 }
3279 3279
3280 3280 void
3281 3281 G1CollectedHeap::setup_surviving_young_words() {
3282 3282 guarantee( _surviving_young_words == NULL, "pre-condition" );
3283 3283 size_t array_length = g1_policy()->young_cset_length();
3284 3284 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3285 3285 if (_surviving_young_words == NULL) {
3286 3286 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3287 3287 "Not enough space for young surv words summary.");
3288 3288 }
3289 3289 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3290 3290 #ifdef ASSERT
3291 3291 for (size_t i = 0; i < array_length; ++i) {
3292 3292 assert( _surviving_young_words[i] == 0, "memset above" );
3293 3293 }
3294 3294 #endif // !ASSERT
3295 3295 }
3296 3296
3297 3297 void
3298 3298 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3299 3299 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3300 3300 size_t array_length = g1_policy()->young_cset_length();
3301 3301 for (size_t i = 0; i < array_length; ++i)
3302 3302 _surviving_young_words[i] += surv_young_words[i];
3303 3303 }
3304 3304
3305 3305 void
3306 3306 G1CollectedHeap::cleanup_surviving_young_words() {
3307 3307 guarantee( _surviving_young_words != NULL, "pre-condition" );
3308 3308 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3309 3309 _surviving_young_words = NULL;
3310 3310 }
3311 3311
3312 3312 // </NEW PREDICTION>
3313 3313
3314 3314 struct PrepareForRSScanningClosure : public HeapRegionClosure {
3315 3315 bool doHeapRegion(HeapRegion *r) {
3316 3316 r->rem_set()->set_iter_claimed(0);
3317 3317 return false;
3318 3318 }
3319 3319 };
3320 3320
3321 3321 #if TASKQUEUE_STATS
3322 3322 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3323 3323 st->print_raw_cr("GC Task Stats");
3324 3324 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3325 3325 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3326 3326 }
3327 3327
3328 3328 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3329 3329 print_taskqueue_stats_hdr(st);
3330 3330
3331 3331 TaskQueueStats totals;
3332 3332 const int n = workers() != NULL ? workers()->total_workers() : 1;
3333 3333 for (int i = 0; i < n; ++i) {
3334 3334 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3335 3335 totals += task_queue(i)->stats;
3336 3336 }
3337 3337 st->print_raw("tot "); totals.print(st); st->cr();
3338 3338
3339 3339 DEBUG_ONLY(totals.verify());
3340 3340 }
3341 3341
3342 3342 void G1CollectedHeap::reset_taskqueue_stats() {
3343 3343 const int n = workers() != NULL ? workers()->total_workers() : 1;
3344 3344 for (int i = 0; i < n; ++i) {
3345 3345 task_queue(i)->stats.reset();
3346 3346 }
3347 3347 }
3348 3348 #endif // TASKQUEUE_STATS
3349 3349
3350 3350 bool
3351 3351 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3352 3352 assert_at_safepoint(true /* should_be_vm_thread */);
3353 3353 guarantee(!is_gc_active(), "collection is not reentrant");
3354 3354
3355 3355 if (GC_locker::check_active_before_gc()) {
3356 3356 return false;
3357 3357 }
3358 3358
3359 3359 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3360 3360 ResourceMark rm;
3361 3361
3362 3362 if (PrintHeapAtGC) {
3363 3363 Universe::print_heap_before_gc();
3364 3364 }
3365 3365
3366 3366 verify_region_sets_optional();
3367 3367
3368 3368 {
3369 3369 // This call will decide whether this pause is an initial-mark
3370 3370 // pause. If it is, during_initial_mark_pause() will return true
3371 3371 // for the duration of this pause.
3372 3372 g1_policy()->decide_on_conc_mark_initiation();
3373 3373
3374 3374 char verbose_str[128];
3375 3375 sprintf(verbose_str, "GC pause ");
3376 3376 if (g1_policy()->in_young_gc_mode()) {
3377 3377 if (g1_policy()->full_young_gcs())
3378 3378 strcat(verbose_str, "(young)");
3379 3379 else
3380 3380 strcat(verbose_str, "(partial)");
3381 3381 }
3382 3382 if (g1_policy()->during_initial_mark_pause()) {
3383 3383 strcat(verbose_str, " (initial-mark)");
3384 3384 // We are about to start a marking cycle, so we increment the
3385 3385 // full collection counter.
3386 3386 increment_total_full_collections();
3387 3387 }
3388 3388
3389 3389 // if PrintGCDetails is on, we'll print long statistics information
3390 3390 // in the collector policy code, so let's not print this as the output
3391 3391 // is messy if we do.
3392 3392 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3393 3393 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3394 3394 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3395 3395
3396 3396 TraceMemoryManagerStats tms(false /* fullGC */);
3397 3397
3398 3398 // If the secondary_free_list is not empty, append it to the
3399 3399 // free_list. No need to wait for the cleanup operation to finish;
3400 3400 // the region allocation code will check the secondary_free_list
3401 3401 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3402 3402 // set, skip this step so that the region allocation code has to
3403 3403 // get entries from the secondary_free_list.
3404 3404 if (!G1StressConcRegionFreeing) {
3405 3405 append_secondary_free_list_if_not_empty_with_lock();
3406 3406 }
3407 3407
3408 3408 increment_gc_time_stamp();
3409 3409
3410 3410 if (g1_policy()->in_young_gc_mode()) {
3411 3411 assert(check_young_list_well_formed(),
3412 3412 "young list should be well formed");
3413 3413 }
3414 3414
3415 3415 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3416 3416 IsGCActiveMark x;
3417 3417
3418 3418 gc_prologue(false);
3419 3419 increment_total_collections(false /* full gc */);
3420 3420
3421 3421 #if G1_REM_SET_LOGGING
3422 3422 gclog_or_tty->print_cr("\nJust chose CS, heap:");
3423 3423 print();
3424 3424 #endif
3425 3425
3426 3426 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3427 3427 HandleMark hm; // Discard invalid handles created during verification
3428 3428 prepare_for_verify();
3429 3429 gclog_or_tty->print(" VerifyBeforeGC:");
3430 3430 Universe::verify(false);
3431 3431 }
3432 3432
3433 3433 COMPILER2_PRESENT(DerivedPointerTable::clear());
3434 3434
3435 3435 // Please see comment in G1CollectedHeap::ref_processing_init()
3436 3436 // to see how reference processing currently works in G1.
3437 3437 //
3438 3438 // We want to turn off ref discovery, if necessary, and turn it back on
3439 3439 // on again later if we do. XXX Dubious: why is discovery disabled?
3440 3440 bool was_enabled = ref_processor()->discovery_enabled();
3441 3441 if (was_enabled) ref_processor()->disable_discovery();
3442 3442
3443 3443 // Forget the current alloc region (we might even choose it to be part
3444 3444 // of the collection set!).
3445 3445 abandon_cur_alloc_region();
3446 3446
3447 3447 // The elapsed time induced by the start time below deliberately elides
3448 3448 // the possible verification above.
3449 3449 double start_time_sec = os::elapsedTime();
3450 3450 size_t start_used_bytes = used();
3451 3451
3452 3452 #if YOUNG_LIST_VERBOSE
3453 3453 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3454 3454 _young_list->print();
3455 3455 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3456 3456 #endif // YOUNG_LIST_VERBOSE
3457 3457
3458 3458 g1_policy()->record_collection_pause_start(start_time_sec,
3459 3459 start_used_bytes);
3460 3460
3461 3461 #if YOUNG_LIST_VERBOSE
3462 3462 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3463 3463 _young_list->print();
3464 3464 #endif // YOUNG_LIST_VERBOSE
3465 3465
3466 3466 if (g1_policy()->during_initial_mark_pause()) {
3467 3467 concurrent_mark()->checkpointRootsInitialPre();
3468 3468 }
3469 3469 save_marks();
3470 3470
3471 3471 // We must do this before any possible evacuation that should propagate
3472 3472 // marks.
3473 3473 if (mark_in_progress()) {
3474 3474 double start_time_sec = os::elapsedTime();
3475 3475
3476 3476 _cm->drainAllSATBBuffers();
3477 3477 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3478 3478 g1_policy()->record_satb_drain_time(finish_mark_ms);
3479 3479 }
3480 3480 // Record the number of elements currently on the mark stack, so we
3481 3481 // only iterate over these. (Since evacuation may add to the mark
3482 3482 // stack, doing more exposes race conditions.) If no mark is in
3483 3483 // progress, this will be zero.
3484 3484 _cm->set_oops_do_bound();
3485 3485
3486 3486 if (mark_in_progress())
3487 3487 concurrent_mark()->newCSet();
3488 3488
3489 3489 #if YOUNG_LIST_VERBOSE
3490 3490 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3491 3491 _young_list->print();
3492 3492 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3493 3493 #endif // YOUNG_LIST_VERBOSE
3494 3494
3495 3495 g1_policy()->choose_collection_set(target_pause_time_ms);
3496 3496
3497 3497 // Nothing to do if we were unable to choose a collection set.
3498 3498 #if G1_REM_SET_LOGGING
3499 3499 gclog_or_tty->print_cr("\nAfter pause, heap:");
3500 3500 print();
3501 3501 #endif
3502 3502 PrepareForRSScanningClosure prepare_for_rs_scan;
3503 3503 collection_set_iterate(&prepare_for_rs_scan);
3504 3504
3505 3505 setup_surviving_young_words();
3506 3506
3507 3507 // Set up the gc allocation regions.
3508 3508 get_gc_alloc_regions();
3509 3509
3510 3510 // Actually do the work...
3511 3511 evacuate_collection_set();
3512 3512
3513 3513 free_collection_set(g1_policy()->collection_set());
3514 3514 g1_policy()->clear_collection_set();
3515 3515
3516 3516 cleanup_surviving_young_words();
3517 3517
3518 3518 // Start a new incremental collection set for the next pause.
3519 3519 g1_policy()->start_incremental_cset_building();
3520 3520
3521 3521 // Clear the _cset_fast_test bitmap in anticipation of adding
3522 3522 // regions to the incremental collection set for the next
3523 3523 // evacuation pause.
3524 3524 clear_cset_fast_test();
3525 3525
3526 3526 if (g1_policy()->in_young_gc_mode()) {
3527 3527 _young_list->reset_sampled_info();
3528 3528
3529 3529 // Don't check the whole heap at this point as the
3530 3530 // GC alloc regions from this pause have been tagged
3531 3531 // as survivors and moved on to the survivor list.
3532 3532 // Survivor regions will fail the !is_young() check.
3533 3533 assert(check_young_list_empty(false /* check_heap */),
3534 3534 "young list should be empty");
3535 3535
3536 3536 #if YOUNG_LIST_VERBOSE
3537 3537 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3538 3538 _young_list->print();
3539 3539 #endif // YOUNG_LIST_VERBOSE
3540 3540
3541 3541 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3542 3542 _young_list->first_survivor_region(),
3543 3543 _young_list->last_survivor_region());
3544 3544
3545 3545 _young_list->reset_auxilary_lists();
3546 3546 }
3547 3547
3548 3548 if (evacuation_failed()) {
3549 3549 _summary_bytes_used = recalculate_used();
3550 3550 } else {
3551 3551 // The "used" of the the collection set have already been subtracted
3552 3552 // when they were freed. Add in the bytes evacuated.
3553 3553 _summary_bytes_used += g1_policy()->bytes_in_to_space();
3554 3554 }
3555 3555
3556 3556 if (g1_policy()->in_young_gc_mode() &&
3557 3557 g1_policy()->during_initial_mark_pause()) {
3558 3558 concurrent_mark()->checkpointRootsInitialPost();
3559 3559 set_marking_started();
3560 3560 // CAUTION: after the doConcurrentMark() call below,
3561 3561 // the concurrent marking thread(s) could be running
3562 3562 // concurrently with us. Make sure that anything after
3563 3563 // this point does not assume that we are the only GC thread
3564 3564 // running. Note: of course, the actual marking work will
3565 3565 // not start until the safepoint itself is released in
3566 3566 // ConcurrentGCThread::safepoint_desynchronize().
3567 3567 doConcurrentMark();
3568 3568 }
3569 3569
3570 3570 #if YOUNG_LIST_VERBOSE
3571 3571 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3572 3572 _young_list->print();
3573 3573 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3574 3574 #endif // YOUNG_LIST_VERBOSE
3575 3575
3576 3576 double end_time_sec = os::elapsedTime();
3577 3577 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3578 3578 g1_policy()->record_pause_time_ms(pause_time_ms);
3579 3579 g1_policy()->record_collection_pause_end();
3580 3580
3581 3581 MemoryService::track_memory_usage();
3582 3582
3583 3583 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3584 3584 HandleMark hm; // Discard invalid handles created during verification
3585 3585 gclog_or_tty->print(" VerifyAfterGC:");
3586 3586 prepare_for_verify();
3587 3587 Universe::verify(false);
3588 3588 }
3589 3589
3590 3590 if (was_enabled) ref_processor()->enable_discovery();
3591 3591
3592 3592 {
3593 3593 size_t expand_bytes = g1_policy()->expansion_amount();
3594 3594 if (expand_bytes > 0) {
3595 3595 size_t bytes_before = capacity();
3596 3596 if (!expand(expand_bytes)) {
3597 3597 // We failed to expand the heap so let's verify that
3598 3598 // committed/uncommitted amount match the backing store
3599 3599 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3600 3600 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3601 3601 }
3602 3602 }
3603 3603 }
3604 3604
3605 3605 if (mark_in_progress()) {
3606 3606 concurrent_mark()->update_g1_committed();
3607 3607 }
3608 3608
3609 3609 #ifdef TRACESPINNING
3610 3610 ParallelTaskTerminator::print_termination_counts();
3611 3611 #endif
3612 3612
3613 3613 gc_epilogue(false);
3614 3614 }
3615 3615
3616 3616 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3617 3617 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3618 3618 print_tracing_info();
3619 3619 vm_exit(-1);
3620 3620 }
3621 3621 }
3622 3622
3623 3623 verify_region_sets_optional();
3624 3624
3625 3625 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3626 3626 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3627 3627
3628 3628 if (PrintHeapAtGC) {
3629 3629 Universe::print_heap_after_gc();
3630 3630 }
3631 3631 if (G1SummarizeRSetStats &&
3632 3632 (G1SummarizeRSetStatsPeriod > 0) &&
3633 3633 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3634 3634 g1_rem_set()->print_summary_info();
3635 3635 }
3636 3636
3637 3637 return true;
3638 3638 }
3639 3639
3640 3640 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3641 3641 {
3642 3642 size_t gclab_word_size;
3643 3643 switch (purpose) {
3644 3644 case GCAllocForSurvived:
3645 3645 gclab_word_size = YoungPLABSize;
3646 3646 break;
3647 3647 case GCAllocForTenured:
3648 3648 gclab_word_size = OldPLABSize;
3649 3649 break;
3650 3650 default:
3651 3651 assert(false, "unknown GCAllocPurpose");
3652 3652 gclab_word_size = OldPLABSize;
3653 3653 break;
3654 3654 }
3655 3655 return gclab_word_size;
3656 3656 }
3657 3657
3658 3658
3659 3659 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
3660 3660 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
3661 3661 // make sure we don't call set_gc_alloc_region() multiple times on
3662 3662 // the same region
3663 3663 assert(r == NULL || !r->is_gc_alloc_region(),
3664 3664 "shouldn't already be a GC alloc region");
3665 3665 assert(r == NULL || !r->isHumongous(),
3666 3666 "humongous regions shouldn't be used as GC alloc regions");
3667 3667
3668 3668 HeapWord* original_top = NULL;
3669 3669 if (r != NULL)
3670 3670 original_top = r->top();
3671 3671
3672 3672 // We will want to record the used space in r as being there before gc.
3673 3673 // One we install it as a GC alloc region it's eligible for allocation.
3674 3674 // So record it now and use it later.
3675 3675 size_t r_used = 0;
3676 3676 if (r != NULL) {
3677 3677 r_used = r->used();
3678 3678
3679 3679 if (G1CollectedHeap::use_parallel_gc_threads()) {
3680 3680 // need to take the lock to guard against two threads calling
3681 3681 // get_gc_alloc_region concurrently (very unlikely but...)
3682 3682 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3683 3683 r->save_marks();
3684 3684 }
3685 3685 }
3686 3686 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
3687 3687 _gc_alloc_regions[purpose] = r;
3688 3688 if (old_alloc_region != NULL) {
3689 3689 // Replace aliases too.
3690 3690 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3691 3691 if (_gc_alloc_regions[ap] == old_alloc_region) {
3692 3692 _gc_alloc_regions[ap] = r;
3693 3693 }
3694 3694 }
3695 3695 }
3696 3696 if (r != NULL) {
3697 3697 push_gc_alloc_region(r);
3698 3698 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
3699 3699 // We are using a region as a GC alloc region after it has been used
3700 3700 // as a mutator allocation region during the current marking cycle.
3701 3701 // The mutator-allocated objects are currently implicitly marked, but
3702 3702 // when we move hr->next_top_at_mark_start() forward at the the end
3703 3703 // of the GC pause, they won't be. We therefore mark all objects in
3704 3704 // the "gap". We do this object-by-object, since marking densely
3705 3705 // does not currently work right with marking bitmap iteration. This
3706 3706 // means we rely on TLAB filling at the start of pauses, and no
3707 3707 // "resuscitation" of filled TLAB's. If we want to do this, we need
3708 3708 // to fix the marking bitmap iteration.
3709 3709 HeapWord* curhw = r->next_top_at_mark_start();
3710 3710 HeapWord* t = original_top;
3711 3711
3712 3712 while (curhw < t) {
3713 3713 oop cur = (oop)curhw;
3714 3714 // We'll assume parallel for generality. This is rare code.
3715 3715 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
3716 3716 curhw = curhw + cur->size();
3717 3717 }
3718 3718 assert(curhw == t, "Should have parsed correctly.");
3719 3719 }
3720 3720 if (G1PolicyVerbose > 1) {
3721 3721 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
3722 3722 "for survivors:", r->bottom(), original_top, r->end());
3723 3723 r->print();
3724 3724 }
3725 3725 g1_policy()->record_before_bytes(r_used);
3726 3726 }
3727 3727 }
3728 3728
3729 3729 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
3730 3730 assert(Thread::current()->is_VM_thread() ||
3731 3731 FreeList_lock->owned_by_self(), "Precondition");
3732 3732 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3733 3733 "Precondition.");
3734 3734 hr->set_is_gc_alloc_region(true);
3735 3735 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3736 3736 _gc_alloc_region_list = hr;
3737 3737 }
3738 3738
3739 3739 #ifdef G1_DEBUG
3740 3740 class FindGCAllocRegion: public HeapRegionClosure {
3741 3741 public:
3742 3742 bool doHeapRegion(HeapRegion* r) {
3743 3743 if (r->is_gc_alloc_region()) {
3744 3744 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
3745 3745 r->hrs_index(), r->bottom());
3746 3746 }
3747 3747 return false;
3748 3748 }
3749 3749 };
3750 3750 #endif // G1_DEBUG
3751 3751
3752 3752 void G1CollectedHeap::forget_alloc_region_list() {
3753 3753 assert_at_safepoint(true /* should_be_vm_thread */);
3754 3754 while (_gc_alloc_region_list != NULL) {
3755 3755 HeapRegion* r = _gc_alloc_region_list;
3756 3756 assert(r->is_gc_alloc_region(), "Invariant.");
3757 3757 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3758 3758 // newly allocated data in order to be able to apply deferred updates
3759 3759 // before the GC is done for verification purposes (i.e to allow
3760 3760 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3761 3761 // collection.
3762 3762 r->ContiguousSpace::set_saved_mark();
3763 3763 _gc_alloc_region_list = r->next_gc_alloc_region();
3764 3764 r->set_next_gc_alloc_region(NULL);
3765 3765 r->set_is_gc_alloc_region(false);
3766 3766 if (r->is_survivor()) {
3767 3767 if (r->is_empty()) {
3768 3768 r->set_not_young();
3769 3769 } else {
3770 3770 _young_list->add_survivor_region(r);
3771 3771 }
3772 3772 }
3773 3773 }
3774 3774 #ifdef G1_DEBUG
3775 3775 FindGCAllocRegion fa;
3776 3776 heap_region_iterate(&fa);
3777 3777 #endif // G1_DEBUG
3778 3778 }
3779 3779
3780 3780
3781 3781 bool G1CollectedHeap::check_gc_alloc_regions() {
3782 3782 // TODO: allocation regions check
3783 3783 return true;
3784 3784 }
3785 3785
3786 3786 void G1CollectedHeap::get_gc_alloc_regions() {
3787 3787 // First, let's check that the GC alloc region list is empty (it should)
3788 3788 assert(_gc_alloc_region_list == NULL, "invariant");
3789 3789
3790 3790 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3791 3791 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3792 3792 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3793 3793
3794 3794 // Create new GC alloc regions.
3795 3795 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3796 3796 _retained_gc_alloc_regions[ap] = NULL;
3797 3797
3798 3798 if (alloc_region != NULL) {
3799 3799 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3800 3800
3801 3801 // let's make sure that the GC alloc region is not tagged as such
3802 3802 // outside a GC operation
3803 3803 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3804 3804
3805 3805 if (alloc_region->in_collection_set() ||
3806 3806 alloc_region->top() == alloc_region->end() ||
3807 3807 alloc_region->top() == alloc_region->bottom() ||
3808 3808 alloc_region->isHumongous()) {
3809 3809 // we will discard the current GC alloc region if
3810 3810 // * it's in the collection set (it can happen!),
3811 3811 // * it's already full (no point in using it),
3812 3812 // * it's empty (this means that it was emptied during
3813 3813 // a cleanup and it should be on the free list now), or
3814 3814 // * it's humongous (this means that it was emptied
3815 3815 // during a cleanup and was added to the free list, but
3816 3816 // has been subseqently used to allocate a humongous
3817 3817 // object that may be less than the region size).
3818 3818
3819 3819 alloc_region = NULL;
3820 3820 }
3821 3821 }
3822 3822
3823 3823 if (alloc_region == NULL) {
3824 3824 // we will get a new GC alloc region
3825 3825 alloc_region = new_gc_alloc_region(ap, HeapRegion::GrainWords);
3826 3826 } else {
3827 3827 // the region was retained from the last collection
3828 3828 ++_gc_alloc_region_counts[ap];
3829 3829 if (G1PrintHeapRegions) {
3830 3830 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
3831 3831 "top "PTR_FORMAT,
3832 3832 alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top());
3833 3833 }
3834 3834 }
3835 3835
3836 3836 if (alloc_region != NULL) {
3837 3837 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3838 3838 set_gc_alloc_region(ap, alloc_region);
3839 3839 }
3840 3840
3841 3841 assert(_gc_alloc_regions[ap] == NULL ||
3842 3842 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3843 3843 "the GC alloc region should be tagged as such");
3844 3844 assert(_gc_alloc_regions[ap] == NULL ||
3845 3845 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3846 3846 "the GC alloc region should be the same as the GC alloc list head");
3847 3847 }
3848 3848 // Set alternative regions for allocation purposes that have reached
3849 3849 // their limit.
3850 3850 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3851 3851 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3852 3852 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3853 3853 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3854 3854 }
3855 3855 }
3856 3856 assert(check_gc_alloc_regions(), "alloc regions messed up");
3857 3857 }
3858 3858
3859 3859 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3860 3860 // We keep a separate list of all regions that have been alloc regions in
3861 3861 // the current collection pause. Forget that now. This method will
3862 3862 // untag the GC alloc regions and tear down the GC alloc region
3863 3863 // list. It's desirable that no regions are tagged as GC alloc
3864 3864 // outside GCs.
3865 3865
3866 3866 forget_alloc_region_list();
3867 3867
3868 3868 // The current alloc regions contain objs that have survived
3869 3869 // collection. Make them no longer GC alloc regions.
3870 3870 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3871 3871 HeapRegion* r = _gc_alloc_regions[ap];
3872 3872 _retained_gc_alloc_regions[ap] = NULL;
3873 3873 _gc_alloc_region_counts[ap] = 0;
3874 3874
3875 3875 if (r != NULL) {
3876 3876 // we retain nothing on _gc_alloc_regions between GCs
3877 3877 set_gc_alloc_region(ap, NULL);
3878 3878
3879 3879 if (r->is_empty()) {
3880 3880 // We didn't actually allocate anything in it; let's just put
3881 3881 // it back on the free list.
3882 3882 _free_list.add_as_tail(r);
3883 3883 } else if (_retain_gc_alloc_region[ap] && !totally) {
3884 3884 // retain it so that we can use it at the beginning of the next GC
3885 3885 _retained_gc_alloc_regions[ap] = r;
3886 3886 }
3887 3887 }
3888 3888 }
3889 3889 }
3890 3890
3891 3891 #ifndef PRODUCT
3892 3892 // Useful for debugging
3893 3893
3894 3894 void G1CollectedHeap::print_gc_alloc_regions() {
3895 3895 gclog_or_tty->print_cr("GC alloc regions");
3896 3896 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3897 3897 HeapRegion* r = _gc_alloc_regions[ap];
3898 3898 if (r == NULL) {
3899 3899 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3900 3900 } else {
3901 3901 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3902 3902 ap, r->bottom(), r->used());
3903 3903 }
3904 3904 }
3905 3905 }
3906 3906 #endif // PRODUCT
3907 3907
3908 3908 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3909 3909 _drain_in_progress = false;
3910 3910 set_evac_failure_closure(cl);
3911 3911 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3912 3912 }
3913 3913
3914 3914 void G1CollectedHeap::finalize_for_evac_failure() {
3915 3915 assert(_evac_failure_scan_stack != NULL &&
3916 3916 _evac_failure_scan_stack->length() == 0,
3917 3917 "Postcondition");
3918 3918 assert(!_drain_in_progress, "Postcondition");
3919 3919 delete _evac_failure_scan_stack;
3920 3920 _evac_failure_scan_stack = NULL;
3921 3921 }
3922 3922
3923 3923
3924 3924
3925 3925 // *** Sequential G1 Evacuation
3926 3926
3927 3927 class G1IsAliveClosure: public BoolObjectClosure {
3928 3928 G1CollectedHeap* _g1;
3929 3929 public:
3930 3930 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3931 3931 void do_object(oop p) { assert(false, "Do not call."); }
3932 3932 bool do_object_b(oop p) {
3933 3933 // It is reachable if it is outside the collection set, or is inside
3934 3934 // and forwarded.
3935 3935
3936 3936 #ifdef G1_DEBUG
3937 3937 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3938 3938 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3939 3939 !_g1->obj_in_cs(p) || p->is_forwarded());
3940 3940 #endif // G1_DEBUG
3941 3941
3942 3942 return !_g1->obj_in_cs(p) || p->is_forwarded();
3943 3943 }
3944 3944 };
3945 3945
3946 3946 class G1KeepAliveClosure: public OopClosure {
3947 3947 G1CollectedHeap* _g1;
3948 3948 public:
3949 3949 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3950 3950 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3951 3951 void do_oop( oop* p) {
3952 3952 oop obj = *p;
3953 3953 #ifdef G1_DEBUG
3954 3954 if (PrintGC && Verbose) {
3955 3955 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3956 3956 p, (void*) obj, (void*) *p);
3957 3957 }
3958 3958 #endif // G1_DEBUG
3959 3959
3960 3960 if (_g1->obj_in_cs(obj)) {
3961 3961 assert( obj->is_forwarded(), "invariant" );
3962 3962 *p = obj->forwardee();
3963 3963 #ifdef G1_DEBUG
3964 3964 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3965 3965 (void*) obj, (void*) *p);
3966 3966 #endif // G1_DEBUG
3967 3967 }
3968 3968 }
3969 3969 };
3970 3970
3971 3971 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3972 3972 private:
3973 3973 G1CollectedHeap* _g1;
3974 3974 DirtyCardQueue *_dcq;
3975 3975 CardTableModRefBS* _ct_bs;
3976 3976
3977 3977 public:
3978 3978 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3979 3979 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3980 3980
3981 3981 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3982 3982 virtual void do_oop( oop* p) { do_oop_work(p); }
3983 3983 template <class T> void do_oop_work(T* p) {
3984 3984 assert(_from->is_in_reserved(p), "paranoia");
3985 3985 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3986 3986 !_from->is_survivor()) {
3987 3987 size_t card_index = _ct_bs->index_for(p);
3988 3988 if (_ct_bs->mark_card_deferred(card_index)) {
3989 3989 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3990 3990 }
3991 3991 }
3992 3992 }
3993 3993 };
3994 3994
3995 3995 class RemoveSelfPointerClosure: public ObjectClosure {
3996 3996 private:
3997 3997 G1CollectedHeap* _g1;
3998 3998 ConcurrentMark* _cm;
3999 3999 HeapRegion* _hr;
4000 4000 size_t _prev_marked_bytes;
4001 4001 size_t _next_marked_bytes;
4002 4002 OopsInHeapRegionClosure *_cl;
4003 4003 public:
4004 4004 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
4005 4005 OopsInHeapRegionClosure* cl) :
4006 4006 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
4007 4007 _next_marked_bytes(0), _cl(cl) {}
4008 4008
4009 4009 size_t prev_marked_bytes() { return _prev_marked_bytes; }
4010 4010 size_t next_marked_bytes() { return _next_marked_bytes; }
4011 4011
4012 4012 // <original comment>
4013 4013 // The original idea here was to coalesce evacuated and dead objects.
4014 4014 // However that caused complications with the block offset table (BOT).
4015 4015 // In particular if there were two TLABs, one of them partially refined.
4016 4016 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
4017 4017 // The BOT entries of the unrefined part of TLAB_2 point to the start
4018 4018 // of TLAB_2. If the last object of the TLAB_1 and the first object
4019 4019 // of TLAB_2 are coalesced, then the cards of the unrefined part
4020 4020 // would point into middle of the filler object.
4021 4021 // The current approach is to not coalesce and leave the BOT contents intact.
4022 4022 // </original comment>
4023 4023 //
4024 4024 // We now reset the BOT when we start the object iteration over the
4025 4025 // region and refine its entries for every object we come across. So
4026 4026 // the above comment is not really relevant and we should be able
4027 4027 // to coalesce dead objects if we want to.
4028 4028 void do_object(oop obj) {
4029 4029 HeapWord* obj_addr = (HeapWord*) obj;
4030 4030 assert(_hr->is_in(obj_addr), "sanity");
4031 4031 size_t obj_size = obj->size();
4032 4032 _hr->update_bot_for_object(obj_addr, obj_size);
4033 4033 if (obj->is_forwarded() && obj->forwardee() == obj) {
4034 4034 // The object failed to move.
4035 4035 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
4036 4036 _cm->markPrev(obj);
4037 4037 assert(_cm->isPrevMarked(obj), "Should be marked!");
4038 4038 _prev_marked_bytes += (obj_size * HeapWordSize);
4039 4039 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
4040 4040 _cm->markAndGrayObjectIfNecessary(obj);
4041 4041 }
4042 4042 obj->set_mark(markOopDesc::prototype());
4043 4043 // While we were processing RSet buffers during the
4044 4044 // collection, we actually didn't scan any cards on the
4045 4045 // collection set, since we didn't want to update remebered
4046 4046 // sets with entries that point into the collection set, given
4047 4047 // that live objects fromthe collection set are about to move
4048 4048 // and such entries will be stale very soon. This change also
4049 4049 // dealt with a reliability issue which involved scanning a
4050 4050 // card in the collection set and coming across an array that
4051 4051 // was being chunked and looking malformed. The problem is
4052 4052 // that, if evacuation fails, we might have remembered set
4053 4053 // entries missing given that we skipped cards on the
4054 4054 // collection set. So, we'll recreate such entries now.
4055 4055 obj->oop_iterate(_cl);
4056 4056 assert(_cm->isPrevMarked(obj), "Should be marked!");
4057 4057 } else {
4058 4058 // The object has been either evacuated or is dead. Fill it with a
4059 4059 // dummy object.
4060 4060 MemRegion mr((HeapWord*)obj, obj_size);
4061 4061 CollectedHeap::fill_with_object(mr);
4062 4062 _cm->clearRangeBothMaps(mr);
4063 4063 }
4064 4064 }
4065 4065 };
4066 4066
4067 4067 void G1CollectedHeap::remove_self_forwarding_pointers() {
4068 4068 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
4069 4069 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
4070 4070 UpdateRSetDeferred deferred_update(_g1h, &dcq);
4071 4071 OopsInHeapRegionClosure *cl;
4072 4072 if (G1DeferredRSUpdate) {
4073 4073 cl = &deferred_update;
4074 4074 } else {
4075 4075 cl = &immediate_update;
4076 4076 }
4077 4077 HeapRegion* cur = g1_policy()->collection_set();
4078 4078 while (cur != NULL) {
4079 4079 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4080 4080 assert(!cur->isHumongous(), "sanity");
4081 4081
4082 4082 if (cur->evacuation_failed()) {
4083 4083 assert(cur->in_collection_set(), "bad CS");
4084 4084 RemoveSelfPointerClosure rspc(_g1h, cur, cl);
4085 4085
4086 4086 cur->reset_bot();
4087 4087 cl->set_region(cur);
4088 4088 cur->object_iterate(&rspc);
4089 4089
4090 4090 // A number of manipulations to make the TAMS be the current top,
4091 4091 // and the marked bytes be the ones observed in the iteration.
4092 4092 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
4093 4093 // The comments below are the postconditions achieved by the
4094 4094 // calls. Note especially the last such condition, which says that
4095 4095 // the count of marked bytes has been properly restored.
4096 4096 cur->note_start_of_marking(false);
4097 4097 // _next_top_at_mark_start == top, _next_marked_bytes == 0
4098 4098 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
4099 4099 // _next_marked_bytes == prev_marked_bytes.
4100 4100 cur->note_end_of_marking();
4101 4101 // _prev_top_at_mark_start == top(),
4102 4102 // _prev_marked_bytes == prev_marked_bytes
4103 4103 }
4104 4104 // If there is no mark in progress, we modified the _next variables
4105 4105 // above needlessly, but harmlessly.
4106 4106 if (_g1h->mark_in_progress()) {
4107 4107 cur->note_start_of_marking(false);
4108 4108 // _next_top_at_mark_start == top, _next_marked_bytes == 0
4109 4109 // _next_marked_bytes == next_marked_bytes.
4110 4110 }
4111 4111
4112 4112 // Now make sure the region has the right index in the sorted array.
4113 4113 g1_policy()->note_change_in_marked_bytes(cur);
4114 4114 }
4115 4115 cur = cur->next_in_collection_set();
4116 4116 }
4117 4117 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4118 4118
4119 4119 // Now restore saved marks, if any.
4120 4120 if (_objs_with_preserved_marks != NULL) {
4121 4121 assert(_preserved_marks_of_objs != NULL, "Both or none.");
4122 4122 guarantee(_objs_with_preserved_marks->length() ==
4123 4123 _preserved_marks_of_objs->length(), "Both or none.");
4124 4124 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4125 4125 oop obj = _objs_with_preserved_marks->at(i);
4126 4126 markOop m = _preserved_marks_of_objs->at(i);
4127 4127 obj->set_mark(m);
4128 4128 }
4129 4129 // Delete the preserved marks growable arrays (allocated on the C heap).
4130 4130 delete _objs_with_preserved_marks;
4131 4131 delete _preserved_marks_of_objs;
4132 4132 _objs_with_preserved_marks = NULL;
4133 4133 _preserved_marks_of_objs = NULL;
4134 4134 }
4135 4135 }
4136 4136
4137 4137 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4138 4138 _evac_failure_scan_stack->push(obj);
4139 4139 }
4140 4140
4141 4141 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4142 4142 assert(_evac_failure_scan_stack != NULL, "precondition");
4143 4143
4144 4144 while (_evac_failure_scan_stack->length() > 0) {
4145 4145 oop obj = _evac_failure_scan_stack->pop();
4146 4146 _evac_failure_closure->set_region(heap_region_containing(obj));
4147 4147 obj->oop_iterate_backwards(_evac_failure_closure);
4148 4148 }
4149 4149 }
4150 4150
4151 4151 oop
4152 4152 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4153 4153 oop old) {
4154 4154 markOop m = old->mark();
4155 4155 oop forward_ptr = old->forward_to_atomic(old);
4156 4156 if (forward_ptr == NULL) {
4157 4157 // Forward-to-self succeeded.
4158 4158 if (_evac_failure_closure != cl) {
4159 4159 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4160 4160 assert(!_drain_in_progress,
4161 4161 "Should only be true while someone holds the lock.");
4162 4162 // Set the global evac-failure closure to the current thread's.
4163 4163 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4164 4164 set_evac_failure_closure(cl);
4165 4165 // Now do the common part.
4166 4166 handle_evacuation_failure_common(old, m);
4167 4167 // Reset to NULL.
4168 4168 set_evac_failure_closure(NULL);
4169 4169 } else {
4170 4170 // The lock is already held, and this is recursive.
4171 4171 assert(_drain_in_progress, "This should only be the recursive case.");
4172 4172 handle_evacuation_failure_common(old, m);
4173 4173 }
4174 4174 return old;
4175 4175 } else {
4176 4176 // Someone else had a place to copy it.
4177 4177 return forward_ptr;
4178 4178 }
4179 4179 }
4180 4180
4181 4181 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4182 4182 set_evacuation_failed(true);
4183 4183
4184 4184 preserve_mark_if_necessary(old, m);
4185 4185
4186 4186 HeapRegion* r = heap_region_containing(old);
4187 4187 if (!r->evacuation_failed()) {
4188 4188 r->set_evacuation_failed(true);
4189 4189 if (G1PrintHeapRegions) {
4190 4190 gclog_or_tty->print("overflow in heap region "PTR_FORMAT" "
4191 4191 "["PTR_FORMAT","PTR_FORMAT")\n",
4192 4192 r, r->bottom(), r->end());
4193 4193 }
4194 4194 }
4195 4195
4196 4196 push_on_evac_failure_scan_stack(old);
4197 4197
4198 4198 if (!_drain_in_progress) {
4199 4199 // prevent recursion in copy_to_survivor_space()
4200 4200 _drain_in_progress = true;
4201 4201 drain_evac_failure_scan_stack();
4202 4202 _drain_in_progress = false;
4203 4203 }
4204 4204 }
4205 4205
4206 4206 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4207 4207 assert(evacuation_failed(), "Oversaving!");
4208 4208 // We want to call the "for_promotion_failure" version only in the
4209 4209 // case of a promotion failure.
4210 4210 if (m->must_be_preserved_for_promotion_failure(obj)) {
4211 4211 if (_objs_with_preserved_marks == NULL) {
4212 4212 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4213 4213 _objs_with_preserved_marks =
4214 4214 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4215 4215 _preserved_marks_of_objs =
4216 4216 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4217 4217 }
4218 4218 _objs_with_preserved_marks->push(obj);
4219 4219 _preserved_marks_of_objs->push(m);
4220 4220 }
4221 4221 }
4222 4222
4223 4223 // *** Parallel G1 Evacuation
4224 4224
4225 4225 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4226 4226 size_t word_size) {
4227 4227 assert(!isHumongous(word_size),
4228 4228 err_msg("we should not be seeing humongous allocation requests "
4229 4229 "during GC, word_size = "SIZE_FORMAT, word_size));
4230 4230
4231 4231 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
4232 4232 // let the caller handle alloc failure
4233 4233 if (alloc_region == NULL) return NULL;
4234 4234
4235 4235 HeapWord* block = alloc_region->par_allocate(word_size);
4236 4236 if (block == NULL) {
4237 4237 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
4238 4238 }
4239 4239 return block;
4240 4240 }
4241 4241
4242 4242 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
4243 4243 bool par) {
4244 4244 // Another thread might have obtained alloc_region for the given
4245 4245 // purpose, and might be attempting to allocate in it, and might
4246 4246 // succeed. Therefore, we can't do the "finalization" stuff on the
4247 4247 // region below until we're sure the last allocation has happened.
4248 4248 // We ensure this by allocating the remaining space with a garbage
4249 4249 // object.
4250 4250 if (par) par_allocate_remaining_space(alloc_region);
4251 4251 // Now we can do the post-GC stuff on the region.
4252 4252 alloc_region->note_end_of_copying();
4253 4253 g1_policy()->record_after_bytes(alloc_region->used());
4254 4254 }
4255 4255
4256 4256 HeapWord*
4257 4257 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
4258 4258 HeapRegion* alloc_region,
4259 4259 bool par,
4260 4260 size_t word_size) {
4261 4261 assert(!isHumongous(word_size),
4262 4262 err_msg("we should not be seeing humongous allocation requests "
4263 4263 "during GC, word_size = "SIZE_FORMAT, word_size));
4264 4264
4265 4265 // We need to make sure we serialize calls to this method. Given
4266 4266 // that the FreeList_lock guards accesses to the free_list anyway,
4267 4267 // and we need to potentially remove a region from it, we'll use it
4268 4268 // to protect the whole call.
4269 4269 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4270 4270
4271 4271 HeapWord* block = NULL;
4272 4272 // In the parallel case, a previous thread to obtain the lock may have
4273 4273 // already assigned a new gc_alloc_region.
4274 4274 if (alloc_region != _gc_alloc_regions[purpose]) {
4275 4275 assert(par, "But should only happen in parallel case.");
4276 4276 alloc_region = _gc_alloc_regions[purpose];
4277 4277 if (alloc_region == NULL) return NULL;
4278 4278 block = alloc_region->par_allocate(word_size);
4279 4279 if (block != NULL) return block;
4280 4280 // Otherwise, continue; this new region is empty, too.
4281 4281 }
4282 4282 assert(alloc_region != NULL, "We better have an allocation region");
4283 4283 retire_alloc_region(alloc_region, par);
4284 4284
4285 4285 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
4286 4286 // Cannot allocate more regions for the given purpose.
4287 4287 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
4288 4288 // Is there an alternative?
4289 4289 if (purpose != alt_purpose) {
4290 4290 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
4291 4291 // Has not the alternative region been aliased?
4292 4292 if (alloc_region != alt_region && alt_region != NULL) {
4293 4293 // Try to allocate in the alternative region.
4294 4294 if (par) {
4295 4295 block = alt_region->par_allocate(word_size);
4296 4296 } else {
4297 4297 block = alt_region->allocate(word_size);
4298 4298 }
4299 4299 // Make an alias.
4300 4300 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
4301 4301 if (block != NULL) {
4302 4302 return block;
4303 4303 }
4304 4304 retire_alloc_region(alt_region, par);
4305 4305 }
4306 4306 // Both the allocation region and the alternative one are full
4307 4307 // and aliased, replace them with a new allocation region.
4308 4308 purpose = alt_purpose;
4309 4309 } else {
4310 4310 set_gc_alloc_region(purpose, NULL);
4311 4311 return NULL;
4312 4312 }
4313 4313 }
4314 4314
4315 4315 // Now allocate a new region for allocation.
4316 4316 alloc_region = new_gc_alloc_region(purpose, word_size);
4317 4317
4318 4318 // let the caller handle alloc failure
4319 4319 if (alloc_region != NULL) {
4320 4320
4321 4321 assert(check_gc_alloc_regions(), "alloc regions messed up");
4322 4322 assert(alloc_region->saved_mark_at_top(),
4323 4323 "Mark should have been saved already.");
4324 4324 // This must be done last: once it's installed, other regions may
4325 4325 // allocate in it (without holding the lock.)
4326 4326 set_gc_alloc_region(purpose, alloc_region);
4327 4327
4328 4328 if (par) {
4329 4329 block = alloc_region->par_allocate(word_size);
4330 4330 } else {
4331 4331 block = alloc_region->allocate(word_size);
4332 4332 }
4333 4333 // Caller handles alloc failure.
4334 4334 } else {
4335 4335 // This sets other apis using the same old alloc region to NULL, also.
4336 4336 set_gc_alloc_region(purpose, NULL);
4337 4337 }
4338 4338 return block; // May be NULL.
4339 4339 }
4340 4340
4341 4341 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
4342 4342 HeapWord* block = NULL;
4343 4343 size_t free_words;
4344 4344 do {
4345 4345 free_words = r->free()/HeapWordSize;
4346 4346 // If there's too little space, no one can allocate, so we're done.
4347 4347 if (free_words < CollectedHeap::min_fill_size()) return;
4348 4348 // Otherwise, try to claim it.
4349 4349 block = r->par_allocate(free_words);
4350 4350 } while (block == NULL);
4351 4351 fill_with_object(block, free_words);
4352 4352 }
4353 4353
4354 4354 #ifndef PRODUCT
4355 4355 bool GCLabBitMapClosure::do_bit(size_t offset) {
4356 4356 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4357 4357 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4358 4358 return true;
4359 4359 }
4360 4360 #endif // PRODUCT
4361 4361
4362 4362 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4363 4363 : _g1h(g1h),
4364 4364 _refs(g1h->task_queue(queue_num)),
4365 4365 _dcq(&g1h->dirty_card_queue_set()),
4366 4366 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4367 4367 _g1_rem(g1h->g1_rem_set()),
4368 4368 _hash_seed(17), _queue_num(queue_num),
4369 4369 _term_attempts(0),
4370 4370 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4371 4371 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4372 4372 _age_table(false),
4373 4373 _strong_roots_time(0), _term_time(0),
4374 4374 _alloc_buffer_waste(0), _undo_waste(0)
4375 4375 {
4376 4376 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4377 4377 // we "sacrifice" entry 0 to keep track of surviving bytes for
4378 4378 // non-young regions (where the age is -1)
4379 4379 // We also add a few elements at the beginning and at the end in
4380 4380 // an attempt to eliminate cache contention
4381 4381 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4382 4382 size_t array_length = PADDING_ELEM_NUM +
4383 4383 real_length +
4384 4384 PADDING_ELEM_NUM;
4385 4385 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4386 4386 if (_surviving_young_words_base == NULL)
4387 4387 vm_exit_out_of_memory(array_length * sizeof(size_t),
4388 4388 "Not enough space for young surv histo.");
4389 4389 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4390 4390 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4391 4391
4392 4392 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4393 4393 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4394 4394
4395 4395 _start = os::elapsedTime();
4396 4396 }
4397 4397
4398 4398 void
4399 4399 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4400 4400 {
4401 4401 st->print_raw_cr("GC Termination Stats");
4402 4402 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4403 4403 " ------waste (KiB)------");
4404 4404 st->print_raw_cr("thr ms ms % ms % attempts"
4405 4405 " total alloc undo");
4406 4406 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4407 4407 " ------- ------- -------");
4408 4408 }
4409 4409
4410 4410 void
4411 4411 G1ParScanThreadState::print_termination_stats(int i,
4412 4412 outputStream* const st) const
4413 4413 {
4414 4414 const double elapsed_ms = elapsed_time() * 1000.0;
4415 4415 const double s_roots_ms = strong_roots_time() * 1000.0;
4416 4416 const double term_ms = term_time() * 1000.0;
4417 4417 st->print_cr("%3d %9.2f %9.2f %6.2f "
4418 4418 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4419 4419 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4420 4420 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4421 4421 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4422 4422 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4423 4423 alloc_buffer_waste() * HeapWordSize / K,
4424 4424 undo_waste() * HeapWordSize / K);
4425 4425 }
4426 4426
4427 4427 #ifdef ASSERT
4428 4428 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4429 4429 assert(ref != NULL, "invariant");
4430 4430 assert(UseCompressedOops, "sanity");
4431 4431 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4432 4432 oop p = oopDesc::load_decode_heap_oop(ref);
4433 4433 assert(_g1h->is_in_g1_reserved(p),
4434 4434 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4435 4435 return true;
4436 4436 }
4437 4437
4438 4438 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4439 4439 assert(ref != NULL, "invariant");
4440 4440 if (has_partial_array_mask(ref)) {
4441 4441 // Must be in the collection set--it's already been copied.
4442 4442 oop p = clear_partial_array_mask(ref);
4443 4443 assert(_g1h->obj_in_cs(p),
4444 4444 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4445 4445 } else {
4446 4446 oop p = oopDesc::load_decode_heap_oop(ref);
4447 4447 assert(_g1h->is_in_g1_reserved(p),
4448 4448 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4449 4449 }
4450 4450 return true;
4451 4451 }
4452 4452
4453 4453 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4454 4454 if (ref.is_narrow()) {
4455 4455 return verify_ref((narrowOop*) ref);
4456 4456 } else {
4457 4457 return verify_ref((oop*) ref);
4458 4458 }
4459 4459 }
4460 4460 #endif // ASSERT
4461 4461
4462 4462 void G1ParScanThreadState::trim_queue() {
4463 4463 StarTask ref;
4464 4464 do {
4465 4465 // Drain the overflow stack first, so other threads can steal.
4466 4466 while (refs()->pop_overflow(ref)) {
4467 4467 deal_with_reference(ref);
4468 4468 }
4469 4469 while (refs()->pop_local(ref)) {
4470 4470 deal_with_reference(ref);
4471 4471 }
4472 4472 } while (!refs()->is_empty());
4473 4473 }
4474 4474
4475 4475 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4476 4476 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4477 4477 _par_scan_state(par_scan_state) { }
4478 4478
4479 4479 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
4480 4480 // This is called _after_ do_oop_work has been called, hence after
4481 4481 // the object has been relocated to its new location and *p points
4482 4482 // to its new location.
4483 4483
4484 4484 T heap_oop = oopDesc::load_heap_oop(p);
4485 4485 if (!oopDesc::is_null(heap_oop)) {
4486 4486 oop obj = oopDesc::decode_heap_oop(heap_oop);
4487 4487 assert((_g1->evacuation_failed()) || (!_g1->obj_in_cs(obj)),
4488 4488 "shouldn't still be in the CSet if evacuation didn't fail.");
4489 4489 HeapWord* addr = (HeapWord*)obj;
4490 4490 if (_g1->is_in_g1_reserved(addr))
4491 4491 _cm->grayRoot(oop(addr));
4492 4492 }
4493 4493 }
4494 4494
4495 4495 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4496 4496 size_t word_sz = old->size();
4497 4497 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4498 4498 // +1 to make the -1 indexes valid...
4499 4499 int young_index = from_region->young_index_in_cset()+1;
4500 4500 assert( (from_region->is_young() && young_index > 0) ||
4501 4501 (!from_region->is_young() && young_index == 0), "invariant" );
4502 4502 G1CollectorPolicy* g1p = _g1->g1_policy();
4503 4503 markOop m = old->mark();
4504 4504 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4505 4505 : m->age();
4506 4506 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4507 4507 word_sz);
4508 4508 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4509 4509 oop obj = oop(obj_ptr);
4510 4510
4511 4511 if (obj_ptr == NULL) {
4512 4512 // This will either forward-to-self, or detect that someone else has
4513 4513 // installed a forwarding pointer.
4514 4514 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4515 4515 return _g1->handle_evacuation_failure_par(cl, old);
4516 4516 }
4517 4517
4518 4518 // We're going to allocate linearly, so might as well prefetch ahead.
4519 4519 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4520 4520
4521 4521 oop forward_ptr = old->forward_to_atomic(obj);
4522 4522 if (forward_ptr == NULL) {
4523 4523 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4524 4524 if (g1p->track_object_age(alloc_purpose)) {
4525 4525 // We could simply do obj->incr_age(). However, this causes a
4526 4526 // performance issue. obj->incr_age() will first check whether
4527 4527 // the object has a displaced mark by checking its mark word;
4528 4528 // getting the mark word from the new location of the object
4529 4529 // stalls. So, given that we already have the mark word and we
4530 4530 // are about to install it anyway, it's better to increase the
4531 4531 // age on the mark word, when the object does not have a
4532 4532 // displaced mark word. We're not expecting many objects to have
4533 4533 // a displaced marked word, so that case is not optimized
4534 4534 // further (it could be...) and we simply call obj->incr_age().
4535 4535
4536 4536 if (m->has_displaced_mark_helper()) {
4537 4537 // in this case, we have to install the mark word first,
4538 4538 // otherwise obj looks to be forwarded (the old mark word,
4539 4539 // which contains the forward pointer, was copied)
4540 4540 obj->set_mark(m);
4541 4541 obj->incr_age();
4542 4542 } else {
4543 4543 m = m->incr_age();
4544 4544 obj->set_mark(m);
4545 4545 }
4546 4546 _par_scan_state->age_table()->add(obj, word_sz);
4547 4547 } else {
4548 4548 obj->set_mark(m);
4549 4549 }
4550 4550
4551 4551 // preserve "next" mark bit
4552 4552 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4553 4553 if (!use_local_bitmaps ||
4554 4554 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4555 4555 // if we couldn't mark it on the local bitmap (this happens when
4556 4556 // the object was not allocated in the GCLab), we have to bite
4557 4557 // the bullet and do the standard parallel mark
4558 4558 _cm->markAndGrayObjectIfNecessary(obj);
4559 4559 }
4560 4560 #if 1
4561 4561 if (_g1->isMarkedNext(old)) {
4562 4562 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4563 4563 }
4564 4564 #endif
4565 4565 }
4566 4566
4567 4567 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4568 4568 surv_young_words[young_index] += word_sz;
4569 4569
4570 4570 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4571 4571 arrayOop(old)->set_length(0);
4572 4572 oop* old_p = set_partial_array_mask(old);
4573 4573 _par_scan_state->push_on_queue(old_p);
4574 4574 } else {
4575 4575 // No point in using the slower heap_region_containing() method,
4576 4576 // given that we know obj is in the heap.
4577 4577 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4578 4578 obj->oop_iterate_backwards(_scanner);
4579 4579 }
4580 4580 } else {
4581 4581 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4582 4582 obj = forward_ptr;
4583 4583 }
4584 4584 return obj;
4585 4585 }
4586 4586
4587 4587 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4588 4588 template <class T>
4589 4589 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
4590 4590 ::do_oop_work(T* p) {
4591 4591 oop obj = oopDesc::load_decode_heap_oop(p);
4592 4592 assert(barrier != G1BarrierRS || obj != NULL,
4593 4593 "Precondition: G1BarrierRS implies obj is nonNull");
4594 4594
4595 4595 // here the null check is implicit in the cset_fast_test() test
4596 4596 if (_g1->in_cset_fast_test(obj)) {
4597 4597 #if G1_REM_SET_LOGGING
4598 4598 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4599 4599 "into CS.", p, (void*) obj);
4600 4600 #endif
4601 4601 if (obj->is_forwarded()) {
4602 4602 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4603 4603 } else {
4604 4604 oop copy_oop = copy_to_survivor_space(obj);
4605 4605 oopDesc::encode_store_heap_oop(p, copy_oop);
4606 4606 }
4607 4607 // When scanning the RS, we only care about objs in CS.
4608 4608 if (barrier == G1BarrierRS) {
4609 4609 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4610 4610 }
4611 4611 }
4612 4612
4613 4613 if (barrier == G1BarrierEvac && obj != NULL) {
4614 4614 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4615 4615 }
4616 4616
4617 4617 if (do_gen_barrier && obj != NULL) {
4618 4618 par_do_barrier(p);
4619 4619 }
4620 4620 }
4621 4621
4622 4622 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4623 4623 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4624 4624
4625 4625 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4626 4626 assert(has_partial_array_mask(p), "invariant");
4627 4627 oop old = clear_partial_array_mask(p);
4628 4628 assert(old->is_objArray(), "must be obj array");
4629 4629 assert(old->is_forwarded(), "must be forwarded");
4630 4630 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4631 4631
4632 4632 objArrayOop obj = objArrayOop(old->forwardee());
4633 4633 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4634 4634 // Process ParGCArrayScanChunk elements now
4635 4635 // and push the remainder back onto queue
4636 4636 int start = arrayOop(old)->length();
4637 4637 int end = obj->length();
4638 4638 int remainder = end - start;
4639 4639 assert(start <= end, "just checking");
4640 4640 if (remainder > 2 * ParGCArrayScanChunk) {
4641 4641 // Test above combines last partial chunk with a full chunk
4642 4642 end = start + ParGCArrayScanChunk;
4643 4643 arrayOop(old)->set_length(end);
4644 4644 // Push remainder.
4645 4645 oop* old_p = set_partial_array_mask(old);
4646 4646 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4647 4647 _par_scan_state->push_on_queue(old_p);
4648 4648 } else {
4649 4649 // Restore length so that the heap remains parsable in
4650 4650 // case of evacuation failure.
4651 4651 arrayOop(old)->set_length(end);
4652 4652 }
4653 4653 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4654 4654 // process our set of indices (include header in first chunk)
4655 4655 obj->oop_iterate_range(&_scanner, start, end);
4656 4656 }
4657 4657
4658 4658 class G1ParEvacuateFollowersClosure : public VoidClosure {
4659 4659 protected:
4660 4660 G1CollectedHeap* _g1h;
4661 4661 G1ParScanThreadState* _par_scan_state;
4662 4662 RefToScanQueueSet* _queues;
4663 4663 ParallelTaskTerminator* _terminator;
4664 4664
4665 4665 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4666 4666 RefToScanQueueSet* queues() { return _queues; }
4667 4667 ParallelTaskTerminator* terminator() { return _terminator; }
4668 4668
4669 4669 public:
4670 4670 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4671 4671 G1ParScanThreadState* par_scan_state,
4672 4672 RefToScanQueueSet* queues,
4673 4673 ParallelTaskTerminator* terminator)
4674 4674 : _g1h(g1h), _par_scan_state(par_scan_state),
4675 4675 _queues(queues), _terminator(terminator) {}
4676 4676
4677 4677 void do_void();
4678 4678
4679 4679 private:
4680 4680 inline bool offer_termination();
4681 4681 };
4682 4682
4683 4683 bool G1ParEvacuateFollowersClosure::offer_termination() {
4684 4684 G1ParScanThreadState* const pss = par_scan_state();
4685 4685 pss->start_term_time();
4686 4686 const bool res = terminator()->offer_termination();
4687 4687 pss->end_term_time();
4688 4688 return res;
4689 4689 }
4690 4690
4691 4691 void G1ParEvacuateFollowersClosure::do_void() {
4692 4692 StarTask stolen_task;
4693 4693 G1ParScanThreadState* const pss = par_scan_state();
4694 4694 pss->trim_queue();
4695 4695
4696 4696 do {
4697 4697 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4698 4698 assert(pss->verify_task(stolen_task), "sanity");
4699 4699 if (stolen_task.is_narrow()) {
4700 4700 pss->deal_with_reference((narrowOop*) stolen_task);
4701 4701 } else {
4702 4702 pss->deal_with_reference((oop*) stolen_task);
4703 4703 }
4704 4704
4705 4705 // We've just processed a reference and we might have made
4706 4706 // available new entries on the queues. So we have to make sure
4707 4707 // we drain the queues as necessary.
4708 4708 pss->trim_queue();
4709 4709 }
4710 4710 } while (!offer_termination());
4711 4711
4712 4712 pss->retire_alloc_buffers();
4713 4713 }
4714 4714
4715 4715 class G1ParTask : public AbstractGangTask {
4716 4716 protected:
4717 4717 G1CollectedHeap* _g1h;
4718 4718 RefToScanQueueSet *_queues;
4719 4719 ParallelTaskTerminator _terminator;
4720 4720 int _n_workers;
4721 4721
4722 4722 Mutex _stats_lock;
4723 4723 Mutex* stats_lock() { return &_stats_lock; }
4724 4724
4725 4725 size_t getNCards() {
4726 4726 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4727 4727 / G1BlockOffsetSharedArray::N_bytes;
4728 4728 }
4729 4729
4730 4730 public:
4731 4731 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4732 4732 : AbstractGangTask("G1 collection"),
4733 4733 _g1h(g1h),
4734 4734 _queues(task_queues),
4735 4735 _terminator(workers, _queues),
4736 4736 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4737 4737 _n_workers(workers)
4738 4738 {}
4739 4739
4740 4740 RefToScanQueueSet* queues() { return _queues; }
4741 4741
4742 4742 RefToScanQueue *work_queue(int i) {
4743 4743 return queues()->queue(i);
4744 4744 }
4745 4745
4746 4746 void work(int i) {
4747 4747 if (i >= _n_workers) return; // no work needed this round
4748 4748
4749 4749 double start_time_ms = os::elapsedTime() * 1000.0;
4750 4750 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4751 4751
4752 4752 ResourceMark rm;
4753 4753 HandleMark hm;
4754 4754
4755 4755 G1ParScanThreadState pss(_g1h, i);
4756 4756 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4757 4757 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4758 4758 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4759 4759
4760 4760 pss.set_evac_closure(&scan_evac_cl);
4761 4761 pss.set_evac_failure_closure(&evac_failure_cl);
4762 4762 pss.set_partial_scan_closure(&partial_scan_cl);
4763 4763
4764 4764 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4765 4765 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4766 4766 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4767 4767 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4768 4768
4769 4769 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4770 4770 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4771 4771 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4772 4772
4773 4773 OopsInHeapRegionClosure *scan_root_cl;
4774 4774 OopsInHeapRegionClosure *scan_perm_cl;
4775 4775
4776 4776 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4777 4777 scan_root_cl = &scan_mark_root_cl;
4778 4778 scan_perm_cl = &scan_mark_perm_cl;
4779 4779 } else {
4780 4780 scan_root_cl = &only_scan_root_cl;
4781 4781 scan_perm_cl = &only_scan_perm_cl;
4782 4782 }
4783 4783
4784 4784 pss.start_strong_roots();
4785 4785 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4786 4786 SharedHeap::SO_AllClasses,
4787 4787 scan_root_cl,
4788 4788 &push_heap_rs_cl,
4789 4789 scan_perm_cl,
4790 4790 i);
4791 4791 pss.end_strong_roots();
4792 4792 {
4793 4793 double start = os::elapsedTime();
4794 4794 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4795 4795 evac.do_void();
4796 4796 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4797 4797 double term_ms = pss.term_time()*1000.0;
4798 4798 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4799 4799 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4800 4800 }
4801 4801 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4802 4802 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4803 4803
4804 4804 // Clean up any par-expanded rem sets.
4805 4805 HeapRegionRemSet::par_cleanup();
4806 4806
4807 4807 if (ParallelGCVerbose) {
4808 4808 MutexLocker x(stats_lock());
4809 4809 pss.print_termination_stats(i);
4810 4810 }
4811 4811
4812 4812 assert(pss.refs()->is_empty(), "should be empty");
4813 4813 double end_time_ms = os::elapsedTime() * 1000.0;
4814 4814 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4815 4815 }
4816 4816 };
4817 4817
4818 4818 // *** Common G1 Evacuation Stuff
4819 4819
4820 4820 // This method is run in a GC worker.
4821 4821
4822 4822 void
4823 4823 G1CollectedHeap::
4824 4824 g1_process_strong_roots(bool collecting_perm_gen,
4825 4825 SharedHeap::ScanningOption so,
4826 4826 OopClosure* scan_non_heap_roots,
4827 4827 OopsInHeapRegionClosure* scan_rs,
4828 4828 OopsInGenClosure* scan_perm,
4829 4829 int worker_i) {
4830 4830 // First scan the strong roots, including the perm gen.
4831 4831 double ext_roots_start = os::elapsedTime();
4832 4832 double closure_app_time_sec = 0.0;
4833 4833
4834 4834 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4835 4835 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4836 4836 buf_scan_perm.set_generation(perm_gen());
4837 4837
4838 4838 // Walk the code cache w/o buffering, because StarTask cannot handle
4839 4839 // unaligned oop locations.
4840 4840 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4841 4841
4842 4842 process_strong_roots(false, // no scoping; this is parallel code
4843 4843 collecting_perm_gen, so,
4844 4844 &buf_scan_non_heap_roots,
4845 4845 &eager_scan_code_roots,
4846 4846 &buf_scan_perm);
4847 4847
4848 4848 // Finish up any enqueued closure apps.
4849 4849 buf_scan_non_heap_roots.done();
4850 4850 buf_scan_perm.done();
4851 4851 double ext_roots_end = os::elapsedTime();
4852 4852 g1_policy()->reset_obj_copy_time(worker_i);
4853 4853 double obj_copy_time_sec =
4854 4854 buf_scan_non_heap_roots.closure_app_seconds() +
4855 4855 buf_scan_perm.closure_app_seconds();
4856 4856 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4857 4857 double ext_root_time_ms =
4858 4858 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4859 4859 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4860 4860
4861 4861 // Scan strong roots in mark stack.
4862 4862 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4863 4863 concurrent_mark()->oops_do(scan_non_heap_roots);
4864 4864 }
4865 4865 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4866 4866 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4867 4867
4868 4868 // XXX What should this be doing in the parallel case?
4869 4869 g1_policy()->record_collection_pause_end_CH_strong_roots();
4870 4870 // Now scan the complement of the collection set.
4871 4871 if (scan_rs != NULL) {
4872 4872 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4873 4873 }
4874 4874 // Finish with the ref_processor roots.
4875 4875 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4876 4876 // We need to treat the discovered reference lists as roots and
4877 4877 // keep entries (which are added by the marking threads) on them
4878 4878 // live until they can be processed at the end of marking.
4879 4879 ref_processor()->weak_oops_do(scan_non_heap_roots);
4880 4880 ref_processor()->oops_do(scan_non_heap_roots);
4881 4881 }
4882 4882 g1_policy()->record_collection_pause_end_G1_strong_roots();
4883 4883 _process_strong_tasks->all_tasks_completed();
4884 4884 }
4885 4885
4886 4886 void
4887 4887 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4888 4888 OopClosure* non_root_closure) {
4889 4889 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4890 4890 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4891 4891 }
4892 4892
4893 4893
4894 4894 class SaveMarksClosure: public HeapRegionClosure {
4895 4895 public:
4896 4896 bool doHeapRegion(HeapRegion* r) {
4897 4897 r->save_marks();
4898 4898 return false;
4899 4899 }
4900 4900 };
4901 4901
4902 4902 void G1CollectedHeap::save_marks() {
4903 4903 if (!CollectedHeap::use_parallel_gc_threads()) {
4904 4904 SaveMarksClosure sm;
4905 4905 heap_region_iterate(&sm);
4906 4906 }
4907 4907 // We do this even in the parallel case
4908 4908 perm_gen()->save_marks();
4909 4909 }
4910 4910
4911 4911 void G1CollectedHeap::evacuate_collection_set() {
4912 4912 set_evacuation_failed(false);
4913 4913
4914 4914 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4915 4915 concurrent_g1_refine()->set_use_cache(false);
4916 4916 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4917 4917
4918 4918 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4919 4919 set_par_threads(n_workers);
4920 4920 G1ParTask g1_par_task(this, n_workers, _task_queues);
4921 4921
4922 4922 init_for_evac_failure(NULL);
4923 4923
4924 4924 rem_set()->prepare_for_younger_refs_iterate(true);
4925 4925
4926 4926 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4927 4927 double start_par = os::elapsedTime();
4928 4928 if (G1CollectedHeap::use_parallel_gc_threads()) {
4929 4929 // The individual threads will set their evac-failure closures.
4930 4930 StrongRootsScope srs(this);
4931 4931 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4932 4932 workers()->run_task(&g1_par_task);
4933 4933 } else {
4934 4934 StrongRootsScope srs(this);
4935 4935 g1_par_task.work(0);
4936 4936 }
4937 4937
4938 4938 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4939 4939 g1_policy()->record_par_time(par_time);
4940 4940 set_par_threads(0);
4941 4941 // Is this the right thing to do here? We don't save marks
4942 4942 // on individual heap regions when we allocate from
4943 4943 // them in parallel, so this seems like the correct place for this.
4944 4944 retire_all_alloc_regions();
4945 4945
4946 4946 // Weak root processing.
4947 4947 // Note: when JSR 292 is enabled and code blobs can contain
4948 4948 // non-perm oops then we will need to process the code blobs
4949 4949 // here too.
4950 4950 {
4951 4951 G1IsAliveClosure is_alive(this);
4952 4952 G1KeepAliveClosure keep_alive(this);
4953 4953 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4954 4954 }
4955 4955 release_gc_alloc_regions(false /* totally */);
4956 4956 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4957 4957
4958 4958 concurrent_g1_refine()->clear_hot_cache();
4959 4959 concurrent_g1_refine()->set_use_cache(true);
4960 4960
4961 4961 finalize_for_evac_failure();
4962 4962
4963 4963 // Must do this before removing self-forwarding pointers, which clears
4964 4964 // the per-region evac-failure flags.
4965 4965 concurrent_mark()->complete_marking_in_collection_set();
4966 4966
4967 4967 if (evacuation_failed()) {
4968 4968 remove_self_forwarding_pointers();
4969 4969 if (PrintGCDetails) {
4970 4970 gclog_or_tty->print(" (to-space overflow)");
4971 4971 } else if (PrintGC) {
4972 4972 gclog_or_tty->print("--");
4973 4973 }
4974 4974 }
4975 4975
4976 4976 if (G1DeferredRSUpdate) {
4977 4977 RedirtyLoggedCardTableEntryFastClosure redirty;
4978 4978 dirty_card_queue_set().set_closure(&redirty);
4979 4979 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4980 4980
4981 4981 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4982 4982 dcq.merge_bufferlists(&dirty_card_queue_set());
4983 4983 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4984 4984 }
4985 4985 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4986 4986 }
4987 4987
4988 4988 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
4989 4989 size_t* pre_used,
4990 4990 FreeRegionList* free_list,
4991 4991 HumongousRegionSet* humongous_proxy_set,
4992 4992 HRRSCleanupTask* hrrs_cleanup_task,
4993 4993 bool par) {
4994 4994 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
4995 4995 if (hr->isHumongous()) {
4996 4996 assert(hr->startsHumongous(), "we should only see starts humongous");
4997 4997 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
4998 4998 } else {
4999 4999 free_region(hr, pre_used, free_list, par);
5000 5000 }
5001 5001 } else {
5002 5002 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5003 5003 }
5004 5004 }
5005 5005
5006 5006 void G1CollectedHeap::free_region(HeapRegion* hr,
5007 5007 size_t* pre_used,
5008 5008 FreeRegionList* free_list,
5009 5009 bool par) {
5010 5010 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5011 5011 assert(!hr->is_empty(), "the region should not be empty");
5012 5012 assert(free_list != NULL, "pre-condition");
5013 5013
5014 5014 *pre_used += hr->used();
5015 5015 hr->hr_clear(par, true /* clear_space */);
5016 5016 free_list->add_as_tail(hr);
5017 5017 }
5018 5018
5019 5019 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5020 5020 size_t* pre_used,
5021 5021 FreeRegionList* free_list,
5022 5022 HumongousRegionSet* humongous_proxy_set,
5023 5023 bool par) {
5024 5024 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5025 5025 assert(free_list != NULL, "pre-condition");
5026 5026 assert(humongous_proxy_set != NULL, "pre-condition");
5027 5027
5028 5028 size_t hr_used = hr->used();
5029 5029 size_t hr_capacity = hr->capacity();
5030 5030 size_t hr_pre_used = 0;
5031 5031 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5032 5032 hr->set_notHumongous();
5033 5033 free_region(hr, &hr_pre_used, free_list, par);
5034 5034
5035 5035 int i = hr->hrs_index() + 1;
5036 5036 size_t num = 1;
5037 5037 while ((size_t) i < n_regions()) {
5038 5038 HeapRegion* curr_hr = _hrs->at(i);
5039 5039 if (!curr_hr->continuesHumongous()) {
5040 5040 break;
5041 5041 }
5042 5042 curr_hr->set_notHumongous();
5043 5043 free_region(curr_hr, &hr_pre_used, free_list, par);
5044 5044 num += 1;
5045 5045 i += 1;
5046 5046 }
5047 5047 assert(hr_pre_used == hr_used,
5048 5048 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5049 5049 "should be the same", hr_pre_used, hr_used));
5050 5050 *pre_used += hr_pre_used;
5051 5051 }
5052 5052
5053 5053 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5054 5054 FreeRegionList* free_list,
5055 5055 HumongousRegionSet* humongous_proxy_set,
5056 5056 bool par) {
5057 5057 if (pre_used > 0) {
5058 5058 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5059 5059 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5060 5060 assert(_summary_bytes_used >= pre_used,
5061 5061 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5062 5062 "should be >= pre_used: "SIZE_FORMAT,
5063 5063 _summary_bytes_used, pre_used));
5064 5064 _summary_bytes_used -= pre_used;
5065 5065 }
5066 5066 if (free_list != NULL && !free_list->is_empty()) {
5067 5067 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5068 5068 _free_list.add_as_tail(free_list);
5069 5069 }
5070 5070 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5071 5071 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5072 5072 _humongous_set.update_from_proxy(humongous_proxy_set);
5073 5073 }
5074 5074 }
5075 5075
5076 5076 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
5077 5077 while (list != NULL) {
5078 5078 guarantee( list->is_young(), "invariant" );
5079 5079
5080 5080 HeapWord* bottom = list->bottom();
5081 5081 HeapWord* end = list->end();
5082 5082 MemRegion mr(bottom, end);
5083 5083 ct_bs->dirty(mr);
5084 5084
5085 5085 list = list->get_next_young_region();
5086 5086 }
5087 5087 }
5088 5088
5089 5089
5090 5090 class G1ParCleanupCTTask : public AbstractGangTask {
5091 5091 CardTableModRefBS* _ct_bs;
5092 5092 G1CollectedHeap* _g1h;
5093 5093 HeapRegion* volatile _su_head;
5094 5094 public:
5095 5095 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5096 5096 G1CollectedHeap* g1h,
5097 5097 HeapRegion* survivor_list) :
5098 5098 AbstractGangTask("G1 Par Cleanup CT Task"),
5099 5099 _ct_bs(ct_bs),
5100 5100 _g1h(g1h),
5101 5101 _su_head(survivor_list)
5102 5102 { }
5103 5103
5104 5104 void work(int i) {
5105 5105 HeapRegion* r;
5106 5106 while (r = _g1h->pop_dirty_cards_region()) {
5107 5107 clear_cards(r);
5108 5108 }
5109 5109 // Redirty the cards of the survivor regions.
5110 5110 dirty_list(&this->_su_head);
5111 5111 }
5112 5112
5113 5113 void clear_cards(HeapRegion* r) {
5114 5114 // Cards for Survivor regions will be dirtied later.
5115 5115 if (!r->is_survivor()) {
5116 5116 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5117 5117 }
5118 5118 }
5119 5119
5120 5120 void dirty_list(HeapRegion* volatile * head_ptr) {
5121 5121 HeapRegion* head;
5122 5122 do {
5123 5123 // Pop region off the list.
5124 5124 head = *head_ptr;
5125 5125 if (head != NULL) {
5126 5126 HeapRegion* r = (HeapRegion*)
5127 5127 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
5128 5128 if (r == head) {
5129 5129 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
5130 5130 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
5131 5131 }
5132 5132 }
5133 5133 } while (*head_ptr != NULL);
5134 5134 }
5135 5135 };
5136 5136
5137 5137
5138 5138 #ifndef PRODUCT
5139 5139 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5140 5140 CardTableModRefBS* _ct_bs;
5141 5141 public:
5142 5142 G1VerifyCardTableCleanup(CardTableModRefBS* ct_bs)
5143 5143 : _ct_bs(ct_bs)
5144 5144 { }
5145 5145 virtual bool doHeapRegion(HeapRegion* r)
5146 5146 {
5147 5147 MemRegion mr(r->bottom(), r->end());
5148 5148 if (r->is_survivor()) {
5149 5149 _ct_bs->verify_dirty_region(mr);
5150 5150 } else {
5151 5151 _ct_bs->verify_clean_region(mr);
5152 5152 }
5153 5153 return false;
5154 5154 }
5155 5155 };
5156 5156 #endif
5157 5157
5158 5158 void G1CollectedHeap::cleanUpCardTable() {
5159 5159 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5160 5160 double start = os::elapsedTime();
5161 5161
5162 5162 // Iterate over the dirty cards region list.
5163 5163 G1ParCleanupCTTask cleanup_task(ct_bs, this,
5164 5164 _young_list->first_survivor_region());
5165 5165
5166 5166 if (ParallelGCThreads > 0) {
5167 5167 set_par_threads(workers()->total_workers());
5168 5168 workers()->run_task(&cleanup_task);
5169 5169 set_par_threads(0);
5170 5170 } else {
5171 5171 while (_dirty_cards_region_list) {
5172 5172 HeapRegion* r = _dirty_cards_region_list;
5173 5173 cleanup_task.clear_cards(r);
5174 5174 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5175 5175 if (_dirty_cards_region_list == r) {
5176 5176 // The last region.
5177 5177 _dirty_cards_region_list = NULL;
5178 5178 }
5179 5179 r->set_next_dirty_cards_region(NULL);
5180 5180 }
5181 5181 // now, redirty the cards of the survivor regions
5182 5182 // (it seemed faster to do it this way, instead of iterating over
5183 5183 // all regions and then clearing / dirtying as appropriate)
5184 5184 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
5185 5185 }
5186 5186
5187 5187 double elapsed = os::elapsedTime() - start;
5188 5188 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
5189 5189 #ifndef PRODUCT
5190 5190 if (G1VerifyCTCleanup || VerifyAfterGC) {
5191 5191 G1VerifyCardTableCleanup cleanup_verifier(ct_bs);
5192 5192 heap_region_iterate(&cleanup_verifier);
5193 5193 }
5194 5194 #endif
5195 5195 }
5196 5196
5197 5197 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5198 5198 size_t pre_used = 0;
5199 5199 FreeRegionList local_free_list("Local List for CSet Freeing");
5200 5200
5201 5201 double young_time_ms = 0.0;
5202 5202 double non_young_time_ms = 0.0;
5203 5203
5204 5204 // Since the collection set is a superset of the the young list,
5205 5205 // all we need to do to clear the young list is clear its
5206 5206 // head and length, and unlink any young regions in the code below
5207 5207 _young_list->clear();
5208 5208
5209 5209 G1CollectorPolicy* policy = g1_policy();
5210 5210
5211 5211 double start_sec = os::elapsedTime();
5212 5212 bool non_young = true;
5213 5213
5214 5214 HeapRegion* cur = cs_head;
5215 5215 int age_bound = -1;
5216 5216 size_t rs_lengths = 0;
5217 5217
5218 5218 while (cur != NULL) {
5219 5219 assert(!is_on_master_free_list(cur), "sanity");
5220 5220
5221 5221 if (non_young) {
5222 5222 if (cur->is_young()) {
5223 5223 double end_sec = os::elapsedTime();
5224 5224 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5225 5225 non_young_time_ms += elapsed_ms;
5226 5226
5227 5227 start_sec = os::elapsedTime();
5228 5228 non_young = false;
5229 5229 }
5230 5230 } else {
5231 5231 double end_sec = os::elapsedTime();
5232 5232 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5233 5233 young_time_ms += elapsed_ms;
5234 5234
5235 5235 start_sec = os::elapsedTime();
5236 5236 non_young = true;
5237 5237 }
5238 5238
5239 5239 rs_lengths += cur->rem_set()->occupied();
5240 5240
5241 5241 HeapRegion* next = cur->next_in_collection_set();
5242 5242 assert(cur->in_collection_set(), "bad CS");
5243 5243 cur->set_next_in_collection_set(NULL);
5244 5244 cur->set_in_collection_set(false);
5245 5245
5246 5246 if (cur->is_young()) {
5247 5247 int index = cur->young_index_in_cset();
5248 5248 guarantee( index != -1, "invariant" );
5249 5249 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
5250 5250 size_t words_survived = _surviving_young_words[index];
5251 5251 cur->record_surv_words_in_group(words_survived);
5252 5252
5253 5253 // At this point the we have 'popped' cur from the collection set
5254 5254 // (linked via next_in_collection_set()) but it is still in the
5255 5255 // young list (linked via next_young_region()). Clear the
5256 5256 // _next_young_region field.
5257 5257 cur->set_next_young_region(NULL);
5258 5258 } else {
5259 5259 int index = cur->young_index_in_cset();
5260 5260 guarantee( index == -1, "invariant" );
5261 5261 }
5262 5262
5263 5263 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5264 5264 (!cur->is_young() && cur->young_index_in_cset() == -1),
5265 5265 "invariant" );
5266 5266
5267 5267 if (!cur->evacuation_failed()) {
5268 5268 // And the region is empty.
5269 5269 assert(!cur->is_empty(), "Should not have empty regions in a CS.");
5270 5270 free_region(cur, &pre_used, &local_free_list, false /* par */);
5271 5271 } else {
5272 5272 cur->uninstall_surv_rate_group();
5273 5273 if (cur->is_young())
5274 5274 cur->set_young_index_in_cset(-1);
5275 5275 cur->set_not_young();
5276 5276 cur->set_evacuation_failed(false);
5277 5277 }
5278 5278 cur = next;
5279 5279 }
5280 5280
5281 5281 policy->record_max_rs_lengths(rs_lengths);
5282 5282 policy->cset_regions_freed();
5283 5283
5284 5284 double end_sec = os::elapsedTime();
5285 5285 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5286 5286 if (non_young)
5287 5287 non_young_time_ms += elapsed_ms;
5288 5288 else
5289 5289 young_time_ms += elapsed_ms;
5290 5290
5291 5291 update_sets_after_freeing_regions(pre_used, &local_free_list,
5292 5292 NULL /* humongous_proxy_set */,
5293 5293 false /* par */);
5294 5294 policy->record_young_free_cset_time_ms(young_time_ms);
5295 5295 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5296 5296 }
5297 5297
5298 5298 // This routine is similar to the above but does not record
5299 5299 // any policy statistics or update free lists; we are abandoning
5300 5300 // the current incremental collection set in preparation of a
5301 5301 // full collection. After the full GC we will start to build up
5302 5302 // the incremental collection set again.
5303 5303 // This is only called when we're doing a full collection
5304 5304 // and is immediately followed by the tearing down of the young list.
5305 5305
5306 5306 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5307 5307 HeapRegion* cur = cs_head;
5308 5308
5309 5309 while (cur != NULL) {
5310 5310 HeapRegion* next = cur->next_in_collection_set();
5311 5311 assert(cur->in_collection_set(), "bad CS");
5312 5312 cur->set_next_in_collection_set(NULL);
5313 5313 cur->set_in_collection_set(false);
5314 5314 cur->set_young_index_in_cset(-1);
5315 5315 cur = next;
5316 5316 }
5317 5317 }
5318 5318
5319 5319 void G1CollectedHeap::set_free_regions_coming() {
5320 5320 if (G1ConcRegionFreeingVerbose) {
5321 5321 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5322 5322 "setting free regions coming");
5323 5323 }
5324 5324
5325 5325 assert(!free_regions_coming(), "pre-condition");
5326 5326 _free_regions_coming = true;
5327 5327 }
5328 5328
5329 5329 void G1CollectedHeap::reset_free_regions_coming() {
5330 5330 {
5331 5331 assert(free_regions_coming(), "pre-condition");
5332 5332 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5333 5333 _free_regions_coming = false;
5334 5334 SecondaryFreeList_lock->notify_all();
5335 5335 }
5336 5336
5337 5337 if (G1ConcRegionFreeingVerbose) {
5338 5338 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5339 5339 "reset free regions coming");
5340 5340 }
5341 5341 }
5342 5342
5343 5343 void G1CollectedHeap::wait_while_free_regions_coming() {
5344 5344 // Most of the time we won't have to wait, so let's do a quick test
5345 5345 // first before we take the lock.
5346 5346 if (!free_regions_coming()) {
5347 5347 return;
5348 5348 }
5349 5349
5350 5350 if (G1ConcRegionFreeingVerbose) {
5351 5351 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5352 5352 "waiting for free regions");
5353 5353 }
5354 5354
5355 5355 {
5356 5356 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5357 5357 while (free_regions_coming()) {
5358 5358 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5359 5359 }
5360 5360 }
5361 5361
5362 5362 if (G1ConcRegionFreeingVerbose) {
5363 5363 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5364 5364 "done waiting for free regions");
5365 5365 }
5366 5366 }
5367 5367
5368 5368 size_t G1CollectedHeap::n_regions() {
5369 5369 return _hrs->length();
5370 5370 }
5371 5371
5372 5372 size_t G1CollectedHeap::max_regions() {
5373 5373 return
5374 5374 (size_t)align_size_up(max_capacity(), HeapRegion::GrainBytes) /
5375 5375 HeapRegion::GrainBytes;
5376 5376 }
5377 5377
5378 5378 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5379 5379 assert(heap_lock_held_for_gc(),
5380 5380 "the heap lock should already be held by or for this thread");
5381 5381 _young_list->push_region(hr);
5382 5382 g1_policy()->set_region_short_lived(hr);
5383 5383 }
5384 5384
5385 5385 class NoYoungRegionsClosure: public HeapRegionClosure {
5386 5386 private:
5387 5387 bool _success;
5388 5388 public:
5389 5389 NoYoungRegionsClosure() : _success(true) { }
5390 5390 bool doHeapRegion(HeapRegion* r) {
5391 5391 if (r->is_young()) {
5392 5392 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5393 5393 r->bottom(), r->end());
5394 5394 _success = false;
5395 5395 }
5396 5396 return false;
5397 5397 }
5398 5398 bool success() { return _success; }
5399 5399 };
5400 5400
5401 5401 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5402 5402 bool ret = _young_list->check_list_empty(check_sample);
5403 5403
5404 5404 if (check_heap) {
5405 5405 NoYoungRegionsClosure closure;
5406 5406 heap_region_iterate(&closure);
5407 5407 ret = ret && closure.success();
5408 5408 }
5409 5409
5410 5410 return ret;
5411 5411 }
5412 5412
5413 5413 void G1CollectedHeap::empty_young_list() {
5414 5414 assert(heap_lock_held_for_gc(),
5415 5415 "the heap lock should already be held by or for this thread");
5416 5416 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5417 5417
5418 5418 _young_list->empty_list();
5419 5419 }
5420 5420
5421 5421 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5422 5422 bool no_allocs = true;
5423 5423 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5424 5424 HeapRegion* r = _gc_alloc_regions[ap];
5425 5425 no_allocs = r == NULL || r->saved_mark_at_top();
5426 5426 }
5427 5427 return no_allocs;
5428 5428 }
5429 5429
5430 5430 void G1CollectedHeap::retire_all_alloc_regions() {
5431 5431 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5432 5432 HeapRegion* r = _gc_alloc_regions[ap];
5433 5433 if (r != NULL) {
5434 5434 // Check for aliases.
5435 5435 bool has_processed_alias = false;
5436 5436 for (int i = 0; i < ap; ++i) {
5437 5437 if (_gc_alloc_regions[i] == r) {
5438 5438 has_processed_alias = true;
5439 5439 break;
5440 5440 }
5441 5441 }
5442 5442 if (!has_processed_alias) {
5443 5443 retire_alloc_region(r, false /* par */);
5444 5444 }
5445 5445 }
5446 5446 }
5447 5447 }
5448 5448
5449 5449 // Done at the start of full GC.
5450 5450 void G1CollectedHeap::tear_down_region_lists() {
5451 5451 _free_list.remove_all();
5452 5452 }
5453 5453
5454 5454 class RegionResetter: public HeapRegionClosure {
5455 5455 G1CollectedHeap* _g1h;
5456 5456 FreeRegionList _local_free_list;
5457 5457
5458 5458 public:
5459 5459 RegionResetter() : _g1h(G1CollectedHeap::heap()),
5460 5460 _local_free_list("Local Free List for RegionResetter") { }
5461 5461
5462 5462 bool doHeapRegion(HeapRegion* r) {
5463 5463 if (r->continuesHumongous()) return false;
5464 5464 if (r->top() > r->bottom()) {
5465 5465 if (r->top() < r->end()) {
5466 5466 Copy::fill_to_words(r->top(),
5467 5467 pointer_delta(r->end(), r->top()));
5468 5468 }
5469 5469 } else {
5470 5470 assert(r->is_empty(), "tautology");
5471 5471 _local_free_list.add_as_tail(r);
5472 5472 }
5473 5473 return false;
5474 5474 }
5475 5475
5476 5476 void update_free_lists() {
5477 5477 _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL,
5478 5478 false /* par */);
5479 5479 }
5480 5480 };
5481 5481
5482 5482 // Done at the end of full GC.
5483 5483 void G1CollectedHeap::rebuild_region_lists() {
5484 5484 // This needs to go at the end of the full GC.
5485 5485 RegionResetter rs;
5486 5486 heap_region_iterate(&rs);
5487 5487 rs.update_free_lists();
5488 5488 }
5489 5489
5490 5490 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5491 5491 _refine_cte_cl->set_concurrent(concurrent);
5492 5492 }
5493 5493
5494 5494 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5495 5495 HeapRegion* hr = heap_region_containing(p);
5496 5496 if (hr == NULL) {
5497 5497 return is_in_permanent(p);
5498 5498 } else {
5499 5499 return hr->is_in(p);
5500 5500 }
5501 5501 }
5502 5502
5503 5503 class VerifyRegionListsClosure : public HeapRegionClosure {
5504 5504 private:
5505 5505 HumongousRegionSet* _humongous_set;
5506 5506 FreeRegionList* _free_list;
5507 5507 size_t _region_count;
5508 5508
5509 5509 public:
5510 5510 VerifyRegionListsClosure(HumongousRegionSet* humongous_set,
5511 5511 FreeRegionList* free_list) :
5512 5512 _humongous_set(humongous_set), _free_list(free_list),
5513 5513 _region_count(0) { }
5514 5514
5515 5515 size_t region_count() { return _region_count; }
5516 5516
5517 5517 bool doHeapRegion(HeapRegion* hr) {
5518 5518 _region_count += 1;
5519 5519
5520 5520 if (hr->continuesHumongous()) {
5521 5521 return false;
5522 5522 }
5523 5523
5524 5524 if (hr->is_young()) {
5525 5525 // TODO
5526 5526 } else if (hr->startsHumongous()) {
5527 5527 _humongous_set->verify_next_region(hr);
5528 5528 } else if (hr->is_empty()) {
5529 5529 _free_list->verify_next_region(hr);
5530 5530 }
5531 5531 return false;
5532 5532 }
5533 5533 };
5534 5534
5535 5535 void G1CollectedHeap::verify_region_sets() {
5536 5536 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5537 5537
5538 5538 // First, check the explicit lists.
5539 5539 _free_list.verify();
5540 5540 {
5541 5541 // Given that a concurrent operation might be adding regions to
5542 5542 // the secondary free list we have to take the lock before
5543 5543 // verifying it.
5544 5544 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5545 5545 _secondary_free_list.verify();
5546 5546 }
5547 5547 _humongous_set.verify();
5548 5548
5549 5549 // If a concurrent region freeing operation is in progress it will
5550 5550 // be difficult to correctly attributed any free regions we come
5551 5551 // across to the correct free list given that they might belong to
5552 5552 // one of several (free_list, secondary_free_list, any local lists,
5553 5553 // etc.). So, if that's the case we will skip the rest of the
5554 5554 // verification operation. Alternatively, waiting for the concurrent
5555 5555 // operation to complete will have a non-trivial effect on the GC's
5556 5556 // operation (no concurrent operation will last longer than the
5557 5557 // interval between two calls to verification) and it might hide
5558 5558 // any issues that we would like to catch during testing.
5559 5559 if (free_regions_coming()) {
5560 5560 return;
5561 5561 }
5562 5562
5563 5563 // Make sure we append the secondary_free_list on the free_list so
5564 5564 // that all free regions we will come across can be safely
5565 5565 // attributed to the free_list.
5566 5566 append_secondary_free_list_if_not_empty_with_lock();
5567 5567
5568 5568 // Finally, make sure that the region accounting in the lists is
5569 5569 // consistent with what we see in the heap.
5570 5570 _humongous_set.verify_start();
5571 5571 _free_list.verify_start();
5572 5572
5573 5573 VerifyRegionListsClosure cl(&_humongous_set, &_free_list);
5574 5574 heap_region_iterate(&cl);
5575 5575
5576 5576 _humongous_set.verify_end();
5577 5577 _free_list.verify_end();
5578 5578 }
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