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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/g1AllocRegion.inline.hpp"
32 32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 34 #include "gc_implementation/g1/g1MarkSweep.hpp"
35 35 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
36 36 #include "gc_implementation/g1/g1RemSet.inline.hpp"
37 37 #include "gc_implementation/g1/heapRegionRemSet.hpp"
38 38 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
39 39 #include "gc_implementation/g1/vm_operations_g1.hpp"
40 40 #include "gc_implementation/shared/isGCActiveMark.hpp"
41 41 #include "memory/gcLocker.inline.hpp"
42 42 #include "memory/genOopClosures.inline.hpp"
43 43 #include "memory/generationSpec.hpp"
44 44 #include "oops/oop.inline.hpp"
45 45 #include "oops/oop.pcgc.inline.hpp"
46 46 #include "runtime/aprofiler.hpp"
47 47 #include "runtime/vmThread.hpp"
48 48
49 49 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
50 50
51 51 // turn it on so that the contents of the young list (scan-only /
52 52 // to-be-collected) are printed at "strategic" points before / during
53 53 // / after the collection --- this is useful for debugging
54 54 #define YOUNG_LIST_VERBOSE 0
55 55 // CURRENT STATUS
56 56 // This file is under construction. Search for "FIXME".
57 57
58 58 // INVARIANTS/NOTES
59 59 //
60 60 // All allocation activity covered by the G1CollectedHeap interface is
61 61 // serialized by acquiring the HeapLock. This happens in mem_allocate
62 62 // and allocate_new_tlab, which are the "entry" points to the
63 63 // allocation code from the rest of the JVM. (Note that this does not
64 64 // apply to TLAB allocation, which is not part of this interface: it
65 65 // is done by clients of this interface.)
66 66
67 67 // Local to this file.
68 68
69 69 class RefineCardTableEntryClosure: public CardTableEntryClosure {
70 70 SuspendibleThreadSet* _sts;
71 71 G1RemSet* _g1rs;
72 72 ConcurrentG1Refine* _cg1r;
73 73 bool _concurrent;
74 74 public:
75 75 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
76 76 G1RemSet* g1rs,
77 77 ConcurrentG1Refine* cg1r) :
78 78 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
79 79 {}
80 80 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
81 81 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
82 82 // This path is executed by the concurrent refine or mutator threads,
83 83 // concurrently, and so we do not care if card_ptr contains references
84 84 // that point into the collection set.
85 85 assert(!oops_into_cset, "should be");
86 86
87 87 if (_concurrent && _sts->should_yield()) {
88 88 // Caller will actually yield.
89 89 return false;
90 90 }
91 91 // Otherwise, we finished successfully; return true.
92 92 return true;
93 93 }
94 94 void set_concurrent(bool b) { _concurrent = b; }
95 95 };
96 96
97 97
98 98 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
99 99 int _calls;
100 100 G1CollectedHeap* _g1h;
101 101 CardTableModRefBS* _ctbs;
102 102 int _histo[256];
103 103 public:
104 104 ClearLoggedCardTableEntryClosure() :
105 105 _calls(0)
106 106 {
107 107 _g1h = G1CollectedHeap::heap();
108 108 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
109 109 for (int i = 0; i < 256; i++) _histo[i] = 0;
110 110 }
111 111 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
112 112 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
113 113 _calls++;
114 114 unsigned char* ujb = (unsigned char*)card_ptr;
115 115 int ind = (int)(*ujb);
116 116 _histo[ind]++;
117 117 *card_ptr = -1;
118 118 }
119 119 return true;
120 120 }
121 121 int calls() { return _calls; }
122 122 void print_histo() {
123 123 gclog_or_tty->print_cr("Card table value histogram:");
124 124 for (int i = 0; i < 256; i++) {
125 125 if (_histo[i] != 0) {
126 126 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
127 127 }
128 128 }
129 129 }
130 130 };
131 131
132 132 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
133 133 int _calls;
134 134 G1CollectedHeap* _g1h;
135 135 CardTableModRefBS* _ctbs;
136 136 public:
137 137 RedirtyLoggedCardTableEntryClosure() :
138 138 _calls(0)
139 139 {
140 140 _g1h = G1CollectedHeap::heap();
141 141 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
142 142 }
143 143 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
144 144 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
145 145 _calls++;
146 146 *card_ptr = 0;
147 147 }
148 148 return true;
149 149 }
150 150 int calls() { return _calls; }
151 151 };
152 152
153 153 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
154 154 public:
155 155 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
156 156 *card_ptr = CardTableModRefBS::dirty_card_val();
157 157 return true;
158 158 }
159 159 };
160 160
161 161 YoungList::YoungList(G1CollectedHeap* g1h)
162 162 : _g1h(g1h), _head(NULL),
163 163 _length(0),
164 164 _last_sampled_rs_lengths(0),
165 165 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
166 166 {
167 167 guarantee( check_list_empty(false), "just making sure..." );
168 168 }
169 169
170 170 void YoungList::push_region(HeapRegion *hr) {
171 171 assert(!hr->is_young(), "should not already be young");
172 172 assert(hr->get_next_young_region() == NULL, "cause it should!");
173 173
174 174 hr->set_next_young_region(_head);
175 175 _head = hr;
176 176
177 177 hr->set_young();
178 178 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
179 179 ++_length;
180 180 }
181 181
182 182 void YoungList::add_survivor_region(HeapRegion* hr) {
183 183 assert(hr->is_survivor(), "should be flagged as survivor region");
184 184 assert(hr->get_next_young_region() == NULL, "cause it should!");
185 185
186 186 hr->set_next_young_region(_survivor_head);
187 187 if (_survivor_head == NULL) {
188 188 _survivor_tail = hr;
189 189 }
190 190 _survivor_head = hr;
191 191
192 192 ++_survivor_length;
193 193 }
194 194
195 195 void YoungList::empty_list(HeapRegion* list) {
196 196 while (list != NULL) {
197 197 HeapRegion* next = list->get_next_young_region();
198 198 list->set_next_young_region(NULL);
199 199 list->uninstall_surv_rate_group();
200 200 list->set_not_young();
201 201 list = next;
202 202 }
203 203 }
204 204
205 205 void YoungList::empty_list() {
206 206 assert(check_list_well_formed(), "young list should be well formed");
207 207
208 208 empty_list(_head);
209 209 _head = NULL;
210 210 _length = 0;
211 211
212 212 empty_list(_survivor_head);
213 213 _survivor_head = NULL;
214 214 _survivor_tail = NULL;
215 215 _survivor_length = 0;
216 216
217 217 _last_sampled_rs_lengths = 0;
218 218
219 219 assert(check_list_empty(false), "just making sure...");
220 220 }
221 221
222 222 bool YoungList::check_list_well_formed() {
223 223 bool ret = true;
224 224
225 225 size_t length = 0;
226 226 HeapRegion* curr = _head;
227 227 HeapRegion* last = NULL;
228 228 while (curr != NULL) {
229 229 if (!curr->is_young()) {
230 230 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
231 231 "incorrectly tagged (y: %d, surv: %d)",
232 232 curr->bottom(), curr->end(),
233 233 curr->is_young(), curr->is_survivor());
234 234 ret = false;
235 235 }
236 236 ++length;
237 237 last = curr;
238 238 curr = curr->get_next_young_region();
239 239 }
240 240 ret = ret && (length == _length);
241 241
242 242 if (!ret) {
243 243 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
244 244 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
245 245 length, _length);
246 246 }
247 247
248 248 return ret;
249 249 }
250 250
251 251 bool YoungList::check_list_empty(bool check_sample) {
252 252 bool ret = true;
253 253
254 254 if (_length != 0) {
255 255 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
256 256 _length);
257 257 ret = false;
258 258 }
259 259 if (check_sample && _last_sampled_rs_lengths != 0) {
260 260 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
261 261 ret = false;
262 262 }
263 263 if (_head != NULL) {
264 264 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
265 265 ret = false;
266 266 }
267 267 if (!ret) {
268 268 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
269 269 }
270 270
271 271 return ret;
272 272 }
273 273
274 274 void
275 275 YoungList::rs_length_sampling_init() {
276 276 _sampled_rs_lengths = 0;
277 277 _curr = _head;
278 278 }
279 279
280 280 bool
281 281 YoungList::rs_length_sampling_more() {
282 282 return _curr != NULL;
283 283 }
284 284
285 285 void
286 286 YoungList::rs_length_sampling_next() {
287 287 assert( _curr != NULL, "invariant" );
288 288 size_t rs_length = _curr->rem_set()->occupied();
289 289
290 290 _sampled_rs_lengths += rs_length;
291 291
292 292 // The current region may not yet have been added to the
293 293 // incremental collection set (it gets added when it is
294 294 // retired as the current allocation region).
295 295 if (_curr->in_collection_set()) {
296 296 // Update the collection set policy information for this region
297 297 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
298 298 }
299 299
300 300 _curr = _curr->get_next_young_region();
301 301 if (_curr == NULL) {
302 302 _last_sampled_rs_lengths = _sampled_rs_lengths;
303 303 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
304 304 }
305 305 }
306 306
307 307 void
308 308 YoungList::reset_auxilary_lists() {
309 309 guarantee( is_empty(), "young list should be empty" );
310 310 assert(check_list_well_formed(), "young list should be well formed");
311 311
312 312 // Add survivor regions to SurvRateGroup.
313 313 _g1h->g1_policy()->note_start_adding_survivor_regions();
314 314 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
315 315
316 316 for (HeapRegion* curr = _survivor_head;
317 317 curr != NULL;
318 318 curr = curr->get_next_young_region()) {
319 319 _g1h->g1_policy()->set_region_survivors(curr);
320 320
321 321 // The region is a non-empty survivor so let's add it to
322 322 // the incremental collection set for the next evacuation
323 323 // pause.
324 324 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
325 325 }
326 326 _g1h->g1_policy()->note_stop_adding_survivor_regions();
327 327
328 328 _head = _survivor_head;
329 329 _length = _survivor_length;
330 330 if (_survivor_head != NULL) {
331 331 assert(_survivor_tail != NULL, "cause it shouldn't be");
332 332 assert(_survivor_length > 0, "invariant");
333 333 _survivor_tail->set_next_young_region(NULL);
334 334 }
335 335
336 336 // Don't clear the survivor list handles until the start of
337 337 // the next evacuation pause - we need it in order to re-tag
338 338 // the survivor regions from this evacuation pause as 'young'
339 339 // at the start of the next.
340 340
341 341 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
342 342
343 343 assert(check_list_well_formed(), "young list should be well formed");
344 344 }
345 345
346 346 void YoungList::print() {
347 347 HeapRegion* lists[] = {_head, _survivor_head};
348 348 const char* names[] = {"YOUNG", "SURVIVOR"};
349 349
350 350 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
351 351 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
352 352 HeapRegion *curr = lists[list];
353 353 if (curr == NULL)
354 354 gclog_or_tty->print_cr(" empty");
355 355 while (curr != NULL) {
356 356 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
357 357 "age: %4d, y: %d, surv: %d",
358 358 curr->bottom(), curr->end(),
359 359 curr->top(),
360 360 curr->prev_top_at_mark_start(),
361 361 curr->next_top_at_mark_start(),
362 362 curr->top_at_conc_mark_count(),
363 363 curr->age_in_surv_rate_group_cond(),
364 364 curr->is_young(),
365 365 curr->is_survivor());
366 366 curr = curr->get_next_young_region();
367 367 }
368 368 }
369 369
370 370 gclog_or_tty->print_cr("");
371 371 }
372 372
373 373 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
374 374 {
375 375 // Claim the right to put the region on the dirty cards region list
376 376 // by installing a self pointer.
377 377 HeapRegion* next = hr->get_next_dirty_cards_region();
378 378 if (next == NULL) {
379 379 HeapRegion* res = (HeapRegion*)
380 380 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
381 381 NULL);
382 382 if (res == NULL) {
383 383 HeapRegion* head;
384 384 do {
385 385 // Put the region to the dirty cards region list.
386 386 head = _dirty_cards_region_list;
387 387 next = (HeapRegion*)
388 388 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
389 389 if (next == head) {
390 390 assert(hr->get_next_dirty_cards_region() == hr,
391 391 "hr->get_next_dirty_cards_region() != hr");
392 392 if (next == NULL) {
393 393 // The last region in the list points to itself.
394 394 hr->set_next_dirty_cards_region(hr);
395 395 } else {
396 396 hr->set_next_dirty_cards_region(next);
397 397 }
398 398 }
399 399 } while (next != head);
400 400 }
401 401 }
402 402 }
403 403
404 404 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
405 405 {
406 406 HeapRegion* head;
407 407 HeapRegion* hr;
408 408 do {
409 409 head = _dirty_cards_region_list;
410 410 if (head == NULL) {
411 411 return NULL;
412 412 }
413 413 HeapRegion* new_head = head->get_next_dirty_cards_region();
414 414 if (head == new_head) {
415 415 // The last region.
416 416 new_head = NULL;
417 417 }
418 418 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
419 419 head);
420 420 } while (hr != head);
421 421 assert(hr != NULL, "invariant");
422 422 hr->set_next_dirty_cards_region(NULL);
423 423 return hr;
424 424 }
425 425
426 426 void G1CollectedHeap::stop_conc_gc_threads() {
427 427 _cg1r->stop();
428 428 _cmThread->stop();
429 429 }
430 430
431 431 #ifdef ASSERT
432 432 // A region is added to the collection set as it is retired
433 433 // so an address p can point to a region which will be in the
434 434 // collection set but has not yet been retired. This method
435 435 // therefore is only accurate during a GC pause after all
436 436 // regions have been retired. It is used for debugging
437 437 // to check if an nmethod has references to objects that can
438 438 // be move during a partial collection. Though it can be
439 439 // inaccurate, it is sufficient for G1 because the conservative
440 440 // implementation of is_scavengable() for G1 will indicate that
441 441 // all nmethods must be scanned during a partial collection.
442 442 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
443 443 HeapRegion* hr = heap_region_containing(p);
444 444 return hr != NULL && hr->in_collection_set();
445 445 }
446 446 #endif
447 447
448 448 // Returns true if the reference points to an object that
449 449 // can move in an incremental collecction.
450 450 bool G1CollectedHeap::is_scavengable(const void* p) {
451 451 G1CollectedHeap* g1h = G1CollectedHeap::heap();
452 452 G1CollectorPolicy* g1p = g1h->g1_policy();
453 453 HeapRegion* hr = heap_region_containing(p);
454 454 if (hr == NULL) {
455 455 // perm gen (or null)
456 456 return false;
457 457 } else {
458 458 return !hr->isHumongous();
459 459 }
460 460 }
461 461
462 462 void G1CollectedHeap::check_ct_logs_at_safepoint() {
463 463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
464 464 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
465 465
466 466 // Count the dirty cards at the start.
467 467 CountNonCleanMemRegionClosure count1(this);
468 468 ct_bs->mod_card_iterate(&count1);
469 469 int orig_count = count1.n();
470 470
471 471 // First clear the logged cards.
472 472 ClearLoggedCardTableEntryClosure clear;
473 473 dcqs.set_closure(&clear);
474 474 dcqs.apply_closure_to_all_completed_buffers();
475 475 dcqs.iterate_closure_all_threads(false);
476 476 clear.print_histo();
477 477
478 478 // Now ensure that there's no dirty cards.
479 479 CountNonCleanMemRegionClosure count2(this);
480 480 ct_bs->mod_card_iterate(&count2);
481 481 if (count2.n() != 0) {
482 482 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
483 483 count2.n(), orig_count);
484 484 }
485 485 guarantee(count2.n() == 0, "Card table should be clean.");
486 486
487 487 RedirtyLoggedCardTableEntryClosure redirty;
488 488 JavaThread::dirty_card_queue_set().set_closure(&redirty);
489 489 dcqs.apply_closure_to_all_completed_buffers();
490 490 dcqs.iterate_closure_all_threads(false);
491 491 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
492 492 clear.calls(), orig_count);
493 493 guarantee(redirty.calls() == clear.calls(),
494 494 "Or else mechanism is broken.");
495 495
496 496 CountNonCleanMemRegionClosure count3(this);
497 497 ct_bs->mod_card_iterate(&count3);
498 498 if (count3.n() != orig_count) {
499 499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 500 orig_count, count3.n());
501 501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 502 }
503 503
504 504 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
505 505 }
506 506
507 507 // Private class members.
508 508
509 509 G1CollectedHeap* G1CollectedHeap::_g1h;
510 510
511 511 // Private methods.
512 512
513 513 HeapRegion*
514 514 G1CollectedHeap::new_region_try_secondary_free_list() {
515 515 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
516 516 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
517 517 if (!_secondary_free_list.is_empty()) {
518 518 if (G1ConcRegionFreeingVerbose) {
519 519 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
520 520 "secondary_free_list has "SIZE_FORMAT" entries",
521 521 _secondary_free_list.length());
522 522 }
523 523 // It looks as if there are free regions available on the
524 524 // secondary_free_list. Let's move them to the free_list and try
525 525 // again to allocate from it.
526 526 append_secondary_free_list();
527 527
528 528 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
529 529 "empty we should have moved at least one entry to the free_list");
530 530 HeapRegion* res = _free_list.remove_head();
531 531 if (G1ConcRegionFreeingVerbose) {
532 532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 533 "allocated "HR_FORMAT" from secondary_free_list",
534 534 HR_FORMAT_PARAMS(res));
535 535 }
536 536 return res;
537 537 }
538 538
539 539 // Wait here until we get notifed either when (a) there are no
540 540 // more free regions coming or (b) some regions have been moved on
541 541 // the secondary_free_list.
542 542 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
543 543 }
544 544
545 545 if (G1ConcRegionFreeingVerbose) {
546 546 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
547 547 "could not allocate from secondary_free_list");
548 548 }
549 549 return NULL;
550 550 }
551 551
552 552 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
553 553 assert(!isHumongous(word_size) ||
554 554 word_size <= (size_t) HeapRegion::GrainWords,
555 555 "the only time we use this to allocate a humongous region is "
556 556 "when we are allocating a single humongous region");
557 557
558 558 HeapRegion* res;
559 559 if (G1StressConcRegionFreeing) {
560 560 if (!_secondary_free_list.is_empty()) {
561 561 if (G1ConcRegionFreeingVerbose) {
562 562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
563 563 "forced to look at the secondary_free_list");
564 564 }
565 565 res = new_region_try_secondary_free_list();
566 566 if (res != NULL) {
567 567 return res;
568 568 }
569 569 }
570 570 }
571 571 res = _free_list.remove_head_or_null();
572 572 if (res == NULL) {
573 573 if (G1ConcRegionFreeingVerbose) {
574 574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 575 "res == NULL, trying the secondary_free_list");
576 576 }
577 577 res = new_region_try_secondary_free_list();
578 578 }
579 579 if (res == NULL && do_expand) {
580 580 if (expand(word_size * HeapWordSize)) {
581 581 // The expansion succeeded and so we should have at least one
582 582 // region on the free list.
583 583 res = _free_list.remove_head();
584 584 }
585 585 }
586 586 if (res != NULL) {
587 587 if (G1PrintHeapRegions) {
588 588 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT","PTR_FORMAT"], "
589 589 "top "PTR_FORMAT, res->hrs_index(),
590 590 res->bottom(), res->end(), res->top());
591 591 }
592 592 }
593 593 return res;
594 594 }
595 595
596 596 HeapRegion* G1CollectedHeap::new_gc_alloc_region(int purpose,
597 597 size_t word_size) {
598 598 HeapRegion* alloc_region = NULL;
599 599 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
600 600 alloc_region = new_region(word_size, true /* do_expand */);
601 601 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
602 602 alloc_region->set_survivor();
603 603 }
604 604 ++_gc_alloc_region_counts[purpose];
605 605 } else {
606 606 g1_policy()->note_alloc_region_limit_reached(purpose);
607 607 }
608 608 return alloc_region;
609 609 }
610 610
611 611 int G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
612 612 size_t word_size) {
613 613 assert(isHumongous(word_size), "word_size should be humongous");
614 614 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
615 615
616 616 int first = -1;
617 617 if (num_regions == 1) {
618 618 // Only one region to allocate, no need to go through the slower
619 619 // path. The caller will attempt the expasion if this fails, so
620 620 // let's not try to expand here too.
621 621 HeapRegion* hr = new_region(word_size, false /* do_expand */);
622 622 if (hr != NULL) {
623 623 first = hr->hrs_index();
624 624 } else {
625 625 first = -1;
626 626 }
627 627 } else {
628 628 // We can't allocate humongous regions while cleanupComplete() is
629 629 // running, since some of the regions we find to be empty might not
630 630 // yet be added to the free list and it is not straightforward to
631 631 // know which list they are on so that we can remove them. Note
632 632 // that we only need to do this if we need to allocate more than
633 633 // one region to satisfy the current humongous allocation
634 634 // request. If we are only allocating one region we use the common
635 635 // region allocation code (see above).
636 636 wait_while_free_regions_coming();
637 637 append_secondary_free_list_if_not_empty_with_lock();
638 638
639 639 if (free_regions() >= num_regions) {
640 640 first = _hrs->find_contiguous(num_regions);
641 641 if (first != -1) {
642 642 for (int i = first; i < first + (int) num_regions; ++i) {
643 643 HeapRegion* hr = _hrs->at(i);
644 644 assert(hr->is_empty(), "sanity");
645 645 assert(is_on_master_free_list(hr), "sanity");
646 646 hr->set_pending_removal(true);
647 647 }
648 648 _free_list.remove_all_pending(num_regions);
649 649 }
650 650 }
651 651 }
652 652 return first;
653 653 }
654 654
655 655 HeapWord*
656 656 G1CollectedHeap::humongous_obj_allocate_initialize_regions(int first,
657 657 size_t num_regions,
658 658 size_t word_size) {
659 659 assert(first != -1, "pre-condition");
660 660 assert(isHumongous(word_size), "word_size should be humongous");
661 661 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
662 662
663 663 // Index of last region in the series + 1.
664 664 int last = first + (int) num_regions;
665 665
666 666 // We need to initialize the region(s) we just discovered. This is
667 667 // a bit tricky given that it can happen concurrently with
668 668 // refinement threads refining cards on these regions and
669 669 // potentially wanting to refine the BOT as they are scanning
670 670 // those cards (this can happen shortly after a cleanup; see CR
671 671 // 6991377). So we have to set up the region(s) carefully and in
672 672 // a specific order.
673 673
674 674 // The word size sum of all the regions we will allocate.
675 675 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
676 676 assert(word_size <= word_size_sum, "sanity");
677 677
678 678 // This will be the "starts humongous" region.
679 679 HeapRegion* first_hr = _hrs->at(first);
680 680 // The header of the new object will be placed at the bottom of
681 681 // the first region.
682 682 HeapWord* new_obj = first_hr->bottom();
683 683 // This will be the new end of the first region in the series that
684 684 // should also match the end of the last region in the seriers.
685 685 HeapWord* new_end = new_obj + word_size_sum;
686 686 // This will be the new top of the first region that will reflect
687 687 // this allocation.
688 688 HeapWord* new_top = new_obj + word_size;
689 689
690 690 // First, we need to zero the header of the space that we will be
691 691 // allocating. When we update top further down, some refinement
692 692 // threads might try to scan the region. By zeroing the header we
693 693 // ensure that any thread that will try to scan the region will
694 694 // come across the zero klass word and bail out.
695 695 //
696 696 // NOTE: It would not have been correct to have used
697 697 // CollectedHeap::fill_with_object() and make the space look like
698 698 // an int array. The thread that is doing the allocation will
699 699 // later update the object header to a potentially different array
700 700 // type and, for a very short period of time, the klass and length
701 701 // fields will be inconsistent. This could cause a refinement
702 702 // thread to calculate the object size incorrectly.
703 703 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
704 704
705 705 // We will set up the first region as "starts humongous". This
706 706 // will also update the BOT covering all the regions to reflect
707 707 // that there is a single object that starts at the bottom of the
708 708 // first region.
709 709 first_hr->set_startsHumongous(new_top, new_end);
710 710
711 711 // Then, if there are any, we will set up the "continues
712 712 // humongous" regions.
713 713 HeapRegion* hr = NULL;
714 714 for (int i = first + 1; i < last; ++i) {
715 715 hr = _hrs->at(i);
716 716 hr->set_continuesHumongous(first_hr);
717 717 }
718 718 // If we have "continues humongous" regions (hr != NULL), then the
719 719 // end of the last one should match new_end.
720 720 assert(hr == NULL || hr->end() == new_end, "sanity");
721 721
722 722 // Up to this point no concurrent thread would have been able to
723 723 // do any scanning on any region in this series. All the top
724 724 // fields still point to bottom, so the intersection between
725 725 // [bottom,top] and [card_start,card_end] will be empty. Before we
726 726 // update the top fields, we'll do a storestore to make sure that
727 727 // no thread sees the update to top before the zeroing of the
728 728 // object header and the BOT initialization.
729 729 OrderAccess::storestore();
730 730
731 731 // Now that the BOT and the object header have been initialized,
732 732 // we can update top of the "starts humongous" region.
733 733 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
734 734 "new_top should be in this region");
735 735 first_hr->set_top(new_top);
736 736
737 737 // Now, we will update the top fields of the "continues humongous"
738 738 // regions. The reason we need to do this is that, otherwise,
739 739 // these regions would look empty and this will confuse parts of
740 740 // G1. For example, the code that looks for a consecutive number
741 741 // of empty regions will consider them empty and try to
742 742 // re-allocate them. We can extend is_empty() to also include
743 743 // !continuesHumongous(), but it is easier to just update the top
744 744 // fields here. The way we set top for all regions (i.e., top ==
745 745 // end for all regions but the last one, top == new_top for the
746 746 // last one) is actually used when we will free up the humongous
747 747 // region in free_humongous_region().
748 748 hr = NULL;
749 749 for (int i = first + 1; i < last; ++i) {
750 750 hr = _hrs->at(i);
751 751 if ((i + 1) == last) {
752 752 // last continues humongous region
753 753 assert(hr->bottom() < new_top && new_top <= hr->end(),
754 754 "new_top should fall on this region");
755 755 hr->set_top(new_top);
756 756 } else {
757 757 // not last one
758 758 assert(new_top > hr->end(), "new_top should be above this region");
759 759 hr->set_top(hr->end());
760 760 }
761 761 }
762 762 // If we have continues humongous regions (hr != NULL), then the
763 763 // end of the last one should match new_end and its top should
764 764 // match new_top.
765 765 assert(hr == NULL ||
766 766 (hr->end() == new_end && hr->top() == new_top), "sanity");
767 767
768 768 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
769 769 _summary_bytes_used += first_hr->used();
770 770 _humongous_set.add(first_hr);
771 771
772 772 return new_obj;
773 773 }
774 774
775 775 // If could fit into free regions w/o expansion, try.
776 776 // Otherwise, if can expand, do so.
777 777 // Otherwise, if using ex regions might help, try with ex given back.
778 778 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
779 779 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
780 780
781 781 verify_region_sets_optional();
782 782
783 783 size_t num_regions =
784 784 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
785 785 size_t x_size = expansion_regions();
786 786 size_t fs = _hrs->free_suffix();
787 787 int first = humongous_obj_allocate_find_first(num_regions, word_size);
788 788 if (first == -1) {
789 789 // The only thing we can do now is attempt expansion.
790 790 if (fs + x_size >= num_regions) {
791 791 // If the number of regions we're trying to allocate for this
792 792 // object is at most the number of regions in the free suffix,
793 793 // then the call to humongous_obj_allocate_find_first() above
794 794 // should have succeeded and we wouldn't be here.
795 795 //
796 796 // We should only be trying to expand when the free suffix is
797 797 // not sufficient for the object _and_ we have some expansion
798 798 // room available.
799 799 assert(num_regions > fs, "earlier allocation should have succeeded");
800 800
801 801 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
802 802 first = humongous_obj_allocate_find_first(num_regions, word_size);
803 803 // If the expansion was successful then the allocation
804 804 // should have been successful.
805 805 assert(first != -1, "this should have worked");
806 806 }
807 807 }
808 808 }
809 809
810 810 HeapWord* result = NULL;
811 811 if (first != -1) {
812 812 result =
813 813 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
814 814 assert(result != NULL, "it should always return a valid result");
815 815 }
816 816
817 817 verify_region_sets_optional();
818 818
819 819 return result;
820 820 }
821 821
822 822 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
823 823 assert_heap_not_locked_and_not_at_safepoint();
824 824 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
825 825
826 826 unsigned int dummy_gc_count_before;
827 827 return attempt_allocation(word_size, &dummy_gc_count_before);
828 828 }
829 829
830 830 HeapWord*
831 831 G1CollectedHeap::mem_allocate(size_t word_size,
832 832 bool is_noref,
833 833 bool is_tlab,
834 834 bool* gc_overhead_limit_was_exceeded) {
835 835 assert_heap_not_locked_and_not_at_safepoint();
836 836 assert(!is_tlab, "mem_allocate() this should not be called directly "
837 837 "to allocate TLABs");
838 838
839 839 // Loop until the allocation is satisified, or unsatisfied after GC.
840 840 for (int try_count = 1; /* we'll return */; try_count += 1) {
841 841 unsigned int gc_count_before;
842 842
843 843 HeapWord* result = NULL;
844 844 if (!isHumongous(word_size)) {
845 845 result = attempt_allocation(word_size, &gc_count_before);
846 846 } else {
847 847 result = attempt_allocation_humongous(word_size, &gc_count_before);
848 848 }
849 849 if (result != NULL) {
850 850 return result;
851 851 }
852 852
853 853 // Create the garbage collection operation...
854 854 VM_G1CollectForAllocation op(gc_count_before, word_size);
855 855 // ...and get the VM thread to execute it.
856 856 VMThread::execute(&op);
857 857
858 858 if (op.prologue_succeeded() && op.pause_succeeded()) {
859 859 // If the operation was successful we'll return the result even
860 860 // if it is NULL. If the allocation attempt failed immediately
861 861 // after a Full GC, it's unlikely we'll be able to allocate now.
862 862 HeapWord* result = op.result();
863 863 if (result != NULL && !isHumongous(word_size)) {
864 864 // Allocations that take place on VM operations do not do any
865 865 // card dirtying and we have to do it here. We only have to do
866 866 // this for non-humongous allocations, though.
867 867 dirty_young_block(result, word_size);
868 868 }
869 869 return result;
870 870 } else {
871 871 assert(op.result() == NULL,
872 872 "the result should be NULL if the VM op did not succeed");
873 873 }
874 874
875 875 // Give a warning if we seem to be looping forever.
876 876 if ((QueuedAllocationWarningCount > 0) &&
877 877 (try_count % QueuedAllocationWarningCount == 0)) {
878 878 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
879 879 }
880 880 }
881 881
882 882 ShouldNotReachHere();
883 883 return NULL;
884 884 }
885 885
886 886 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
887 887 unsigned int *gc_count_before_ret) {
888 888 // Make sure you read the note in attempt_allocation_humongous().
889 889
890 890 assert_heap_not_locked_and_not_at_safepoint();
891 891 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
892 892 "be called for humongous allocation requests");
893 893
894 894 // We should only get here after the first-level allocation attempt
895 895 // (attempt_allocation()) failed to allocate.
896 896
897 897 // We will loop until a) we manage to successfully perform the
898 898 // allocation or b) we successfully schedule a collection which
899 899 // fails to perform the allocation. b) is the only case when we'll
900 900 // return NULL.
901 901 HeapWord* result = NULL;
902 902 for (int try_count = 1; /* we'll return */; try_count += 1) {
903 903 bool should_try_gc;
904 904 unsigned int gc_count_before;
905 905
906 906 {
907 907 MutexLockerEx x(Heap_lock);
908 908
909 909 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
910 910 false /* bot_updates */);
911 911 if (result != NULL) {
912 912 return result;
913 913 }
914 914
915 915 // If we reach here, attempt_allocation_locked() above failed to
916 916 // allocate a new region. So the mutator alloc region should be NULL.
917 917 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
918 918
919 919 if (GC_locker::is_active_and_needs_gc()) {
920 920 if (g1_policy()->can_expand_young_list()) {
921 921 result = _mutator_alloc_region.attempt_allocation_force(word_size,
922 922 false /* bot_updates */);
923 923 if (result != NULL) {
924 924 return result;
925 925 }
926 926 }
927 927 should_try_gc = false;
928 928 } else {
929 929 // Read the GC count while still holding the Heap_lock.
930 930 gc_count_before = SharedHeap::heap()->total_collections();
931 931 should_try_gc = true;
932 932 }
933 933 }
934 934
935 935 if (should_try_gc) {
936 936 bool succeeded;
937 937 result = do_collection_pause(word_size, gc_count_before, &succeeded);
938 938 if (result != NULL) {
939 939 assert(succeeded, "only way to get back a non-NULL result");
940 940 return result;
941 941 }
942 942
943 943 if (succeeded) {
944 944 // If we get here we successfully scheduled a collection which
945 945 // failed to allocate. No point in trying to allocate
946 946 // further. We'll just return NULL.
947 947 MutexLockerEx x(Heap_lock);
948 948 *gc_count_before_ret = SharedHeap::heap()->total_collections();
949 949 return NULL;
950 950 }
951 951 } else {
952 952 GC_locker::stall_until_clear();
953 953 }
954 954
955 955 // We can reach here if we were unsuccessul in scheduling a
956 956 // collection (because another thread beat us to it) or if we were
957 957 // stalled due to the GC locker. In either can we should retry the
958 958 // allocation attempt in case another thread successfully
959 959 // performed a collection and reclaimed enough space. We do the
960 960 // first attempt (without holding the Heap_lock) here and the
961 961 // follow-on attempt will be at the start of the next loop
962 962 // iteration (after taking the Heap_lock).
963 963 result = _mutator_alloc_region.attempt_allocation(word_size,
964 964 false /* bot_updates */);
965 965 if (result != NULL ){
966 966 return result;
967 967 }
968 968
969 969 // Give a warning if we seem to be looping forever.
970 970 if ((QueuedAllocationWarningCount > 0) &&
971 971 (try_count % QueuedAllocationWarningCount == 0)) {
972 972 warning("G1CollectedHeap::attempt_allocation_slow() "
973 973 "retries %d times", try_count);
974 974 }
975 975 }
976 976
977 977 ShouldNotReachHere();
978 978 return NULL;
979 979 }
980 980
981 981 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
982 982 unsigned int * gc_count_before_ret) {
983 983 // The structure of this method has a lot of similarities to
984 984 // attempt_allocation_slow(). The reason these two were not merged
985 985 // into a single one is that such a method would require several "if
986 986 // allocation is not humongous do this, otherwise do that"
987 987 // conditional paths which would obscure its flow. In fact, an early
988 988 // version of this code did use a unified method which was harder to
989 989 // follow and, as a result, it had subtle bugs that were hard to
990 990 // track down. So keeping these two methods separate allows each to
991 991 // be more readable. It will be good to keep these two in sync as
992 992 // much as possible.
993 993
994 994 assert_heap_not_locked_and_not_at_safepoint();
995 995 assert(isHumongous(word_size), "attempt_allocation_humongous() "
996 996 "should only be called for humongous allocations");
997 997
998 998 // We will loop until a) we manage to successfully perform the
999 999 // allocation or b) we successfully schedule a collection which
1000 1000 // fails to perform the allocation. b) is the only case when we'll
1001 1001 // return NULL.
1002 1002 HeapWord* result = NULL;
1003 1003 for (int try_count = 1; /* we'll return */; try_count += 1) {
1004 1004 bool should_try_gc;
1005 1005 unsigned int gc_count_before;
1006 1006
1007 1007 {
1008 1008 MutexLockerEx x(Heap_lock);
1009 1009
1010 1010 // Given that humongous objects are not allocated in young
1011 1011 // regions, we'll first try to do the allocation without doing a
1012 1012 // collection hoping that there's enough space in the heap.
1013 1013 result = humongous_obj_allocate(word_size);
1014 1014 if (result != NULL) {
1015 1015 return result;
1016 1016 }
1017 1017
1018 1018 if (GC_locker::is_active_and_needs_gc()) {
1019 1019 should_try_gc = false;
1020 1020 } else {
1021 1021 // Read the GC count while still holding the Heap_lock.
1022 1022 gc_count_before = SharedHeap::heap()->total_collections();
1023 1023 should_try_gc = true;
1024 1024 }
1025 1025 }
1026 1026
1027 1027 if (should_try_gc) {
1028 1028 // If we failed to allocate the humongous object, we should try to
1029 1029 // do a collection pause (if we're allowed) in case it reclaims
1030 1030 // enough space for the allocation to succeed after the pause.
1031 1031
1032 1032 bool succeeded;
1033 1033 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1034 1034 if (result != NULL) {
1035 1035 assert(succeeded, "only way to get back a non-NULL result");
1036 1036 return result;
1037 1037 }
1038 1038
1039 1039 if (succeeded) {
1040 1040 // If we get here we successfully scheduled a collection which
1041 1041 // failed to allocate. No point in trying to allocate
1042 1042 // further. We'll just return NULL.
1043 1043 MutexLockerEx x(Heap_lock);
1044 1044 *gc_count_before_ret = SharedHeap::heap()->total_collections();
1045 1045 return NULL;
1046 1046 }
1047 1047 } else {
1048 1048 GC_locker::stall_until_clear();
1049 1049 }
1050 1050
1051 1051 // We can reach here if we were unsuccessul in scheduling a
1052 1052 // collection (because another thread beat us to it) or if we were
1053 1053 // stalled due to the GC locker. In either can we should retry the
1054 1054 // allocation attempt in case another thread successfully
1055 1055 // performed a collection and reclaimed enough space. Give a
1056 1056 // warning if we seem to be looping forever.
1057 1057
1058 1058 if ((QueuedAllocationWarningCount > 0) &&
1059 1059 (try_count % QueuedAllocationWarningCount == 0)) {
1060 1060 warning("G1CollectedHeap::attempt_allocation_humongous() "
1061 1061 "retries %d times", try_count);
1062 1062 }
1063 1063 }
1064 1064
1065 1065 ShouldNotReachHere();
1066 1066 return NULL;
1067 1067 }
1068 1068
1069 1069 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1070 1070 bool expect_null_mutator_alloc_region) {
1071 1071 assert_at_safepoint(true /* should_be_vm_thread */);
1072 1072 assert(_mutator_alloc_region.get() == NULL ||
1073 1073 !expect_null_mutator_alloc_region,
1074 1074 "the current alloc region was unexpectedly found to be non-NULL");
1075 1075
1076 1076 if (!isHumongous(word_size)) {
1077 1077 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1078 1078 false /* bot_updates */);
1079 1079 } else {
1080 1080 return humongous_obj_allocate(word_size);
1081 1081 }
1082 1082
1083 1083 ShouldNotReachHere();
1084 1084 }
1085 1085
1086 1086 void G1CollectedHeap::abandon_gc_alloc_regions() {
1087 1087 // first, make sure that the GC alloc region list is empty (it should!)
1088 1088 assert(_gc_alloc_region_list == NULL, "invariant");
1089 1089 release_gc_alloc_regions(true /* totally */);
1090 1090 }
1091 1091
1092 1092 class PostMCRemSetClearClosure: public HeapRegionClosure {
1093 1093 ModRefBarrierSet* _mr_bs;
1094 1094 public:
1095 1095 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1096 1096 bool doHeapRegion(HeapRegion* r) {
1097 1097 r->reset_gc_time_stamp();
1098 1098 if (r->continuesHumongous())
1099 1099 return false;
1100 1100 HeapRegionRemSet* hrrs = r->rem_set();
1101 1101 if (hrrs != NULL) hrrs->clear();
1102 1102 // You might think here that we could clear just the cards
1103 1103 // corresponding to the used region. But no: if we leave a dirty card
1104 1104 // in a region we might allocate into, then it would prevent that card
1105 1105 // from being enqueued, and cause it to be missed.
1106 1106 // Re: the performance cost: we shouldn't be doing full GC anyway!
1107 1107 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1108 1108 return false;
1109 1109 }
1110 1110 };
1111 1111
1112 1112
1113 1113 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1114 1114 ModRefBarrierSet* _mr_bs;
1115 1115 public:
1116 1116 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1117 1117 bool doHeapRegion(HeapRegion* r) {
1118 1118 if (r->continuesHumongous()) return false;
1119 1119 if (r->used_region().word_size() != 0) {
1120 1120 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1121 1121 }
1122 1122 return false;
1123 1123 }
1124 1124 };
1125 1125
1126 1126 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1127 1127 G1CollectedHeap* _g1h;
1128 1128 UpdateRSOopClosure _cl;
1129 1129 int _worker_i;
1130 1130 public:
1131 1131 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1132 1132 _cl(g1->g1_rem_set(), worker_i),
1133 1133 _worker_i(worker_i),
1134 1134 _g1h(g1)
1135 1135 { }
1136 1136
1137 1137 bool doHeapRegion(HeapRegion* r) {
1138 1138 if (!r->continuesHumongous()) {
1139 1139 _cl.set_from(r);
1140 1140 r->oop_iterate(&_cl);
1141 1141 }
1142 1142 return false;
1143 1143 }
1144 1144 };
1145 1145
1146 1146 class ParRebuildRSTask: public AbstractGangTask {
1147 1147 G1CollectedHeap* _g1;
1148 1148 public:
1149 1149 ParRebuildRSTask(G1CollectedHeap* g1)
1150 1150 : AbstractGangTask("ParRebuildRSTask"),
1151 1151 _g1(g1)
1152 1152 { }
1153 1153
1154 1154 void work(int i) {
1155 1155 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1156 1156 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1157 1157 HeapRegion::RebuildRSClaimValue);
1158 1158 }
1159 1159 };
1160 1160
1161 1161 bool G1CollectedHeap::do_collection(bool explicit_gc,
1162 1162 bool clear_all_soft_refs,
1163 1163 size_t word_size) {
1164 1164 assert_at_safepoint(true /* should_be_vm_thread */);
1165 1165
1166 1166 if (GC_locker::check_active_before_gc()) {
1167 1167 return false;
1168 1168 }
1169 1169
1170 1170 SvcGCMarker sgcm(SvcGCMarker::FULL);
1171 1171 ResourceMark rm;
1172 1172
1173 1173 if (PrintHeapAtGC) {
1174 1174 Universe::print_heap_before_gc();
1175 1175 }
1176 1176
1177 1177 verify_region_sets_optional();
1178 1178
1179 1179 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1180 1180 collector_policy()->should_clear_all_soft_refs();
1181 1181
1182 1182 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1183 1183
1184 1184 {
1185 1185 IsGCActiveMark x;
1186 1186
1187 1187 // Timing
1188 1188 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1189 1189 assert(!system_gc || explicit_gc, "invariant");
1190 1190 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1191 1191 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1192 1192 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1193 1193 PrintGC, true, gclog_or_tty);
1194 1194
1195 1195 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1196 1196 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1197 1197
1198 1198 double start = os::elapsedTime();
1199 1199 g1_policy()->record_full_collection_start();
1200 1200
1201 1201 wait_while_free_regions_coming();
1202 1202 append_secondary_free_list_if_not_empty_with_lock();
1203 1203
1204 1204 gc_prologue(true);
1205 1205 increment_total_collections(true /* full gc */);
1206 1206
1207 1207 size_t g1h_prev_used = used();
1208 1208 assert(used() == recalculate_used(), "Should be equal");
1209 1209
1210 1210 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1211 1211 HandleMark hm; // Discard invalid handles created during verification
1212 1212 gclog_or_tty->print(" VerifyBeforeGC:");
1213 1213 prepare_for_verify();
1214 1214 Universe::verify(true);
1215 1215 }
1216 1216
1217 1217 COMPILER2_PRESENT(DerivedPointerTable::clear());
1218 1218
1219 1219 // We want to discover references, but not process them yet.
1220 1220 // This mode is disabled in
1221 1221 // instanceRefKlass::process_discovered_references if the
1222 1222 // generation does some collection work, or
1223 1223 // instanceRefKlass::enqueue_discovered_references if the
1224 1224 // generation returns without doing any work.
1225 1225 ref_processor()->disable_discovery();
1226 1226 ref_processor()->abandon_partial_discovery();
1227 1227 ref_processor()->verify_no_references_recorded();
1228 1228
1229 1229 // Abandon current iterations of concurrent marking and concurrent
1230 1230 // refinement, if any are in progress.
1231 1231 concurrent_mark()->abort();
1232 1232
1233 1233 // Make sure we'll choose a new allocation region afterwards.
1234 1234 release_mutator_alloc_region();
1235 1235 abandon_gc_alloc_regions();
1236 1236 g1_rem_set()->cleanupHRRS();
1237 1237 tear_down_region_lists();
1238 1238
1239 1239 // We may have added regions to the current incremental collection
1240 1240 // set between the last GC or pause and now. We need to clear the
1241 1241 // incremental collection set and then start rebuilding it afresh
1242 1242 // after this full GC.
1243 1243 abandon_collection_set(g1_policy()->inc_cset_head());
1244 1244 g1_policy()->clear_incremental_cset();
1245 1245 g1_policy()->stop_incremental_cset_building();
1246 1246
1247 1247 if (g1_policy()->in_young_gc_mode()) {
1248 1248 empty_young_list();
1249 1249 g1_policy()->set_full_young_gcs(true);
1250 1250 }
1251 1251
1252 1252 // See the comment in G1CollectedHeap::ref_processing_init() about
1253 1253 // how reference processing currently works in G1.
1254 1254
1255 1255 // Temporarily make reference _discovery_ single threaded (non-MT).
1256 1256 ReferenceProcessorMTDiscoveryMutator rp_disc_ser(ref_processor(), false);
1257 1257
1258 1258 // Temporarily make refs discovery atomic
1259 1259 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
1260 1260
1261 1261 // Temporarily clear _is_alive_non_header
1262 1262 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
1263 1263
1264 1264 ref_processor()->enable_discovery();
1265 1265 ref_processor()->setup_policy(do_clear_all_soft_refs);
1266 1266
1267 1267 // Do collection work
1268 1268 {
1269 1269 HandleMark hm; // Discard invalid handles created during gc
1270 1270 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
1271 1271 }
1272 1272 assert(free_regions() == 0, "we should not have added any free regions");
1273 1273 rebuild_region_lists();
1274 1274
1275 1275 _summary_bytes_used = recalculate_used();
1276 1276
1277 1277 ref_processor()->enqueue_discovered_references();
1278 1278
1279 1279 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1280 1280
1281 1281 MemoryService::track_memory_usage();
1282 1282
1283 1283 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1284 1284 HandleMark hm; // Discard invalid handles created during verification
1285 1285 gclog_or_tty->print(" VerifyAfterGC:");
1286 1286 prepare_for_verify();
1287 1287 Universe::verify(false);
1288 1288 }
1289 1289 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1290 1290
1291 1291 reset_gc_time_stamp();
1292 1292 // Since everything potentially moved, we will clear all remembered
1293 1293 // sets, and clear all cards. Later we will rebuild remebered
1294 1294 // sets. We will also reset the GC time stamps of the regions.
1295 1295 PostMCRemSetClearClosure rs_clear(mr_bs());
1296 1296 heap_region_iterate(&rs_clear);
1297 1297
1298 1298 // Resize the heap if necessary.
1299 1299 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1300 1300
1301 1301 if (_cg1r->use_cache()) {
1302 1302 _cg1r->clear_and_record_card_counts();
1303 1303 _cg1r->clear_hot_cache();
1304 1304 }
1305 1305
1306 1306 // Rebuild remembered sets of all regions.
1307 1307
1308 1308 if (G1CollectedHeap::use_parallel_gc_threads()) {
1309 1309 ParRebuildRSTask rebuild_rs_task(this);
1310 1310 assert(check_heap_region_claim_values(
1311 1311 HeapRegion::InitialClaimValue), "sanity check");
1312 1312 set_par_threads(workers()->total_workers());
1313 1313 workers()->run_task(&rebuild_rs_task);
1314 1314 set_par_threads(0);
1315 1315 assert(check_heap_region_claim_values(
1316 1316 HeapRegion::RebuildRSClaimValue), "sanity check");
1317 1317 reset_heap_region_claim_values();
1318 1318 } else {
1319 1319 RebuildRSOutOfRegionClosure rebuild_rs(this);
1320 1320 heap_region_iterate(&rebuild_rs);
1321 1321 }
1322 1322
1323 1323 if (PrintGC) {
1324 1324 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1325 1325 }
1326 1326
1327 1327 if (true) { // FIXME
1328 1328 // Ask the permanent generation to adjust size for full collections
1329 1329 perm()->compute_new_size();
1330 1330 }
1331 1331
1332 1332 // Start a new incremental collection set for the next pause
1333 1333 assert(g1_policy()->collection_set() == NULL, "must be");
1334 1334 g1_policy()->start_incremental_cset_building();
1335 1335
1336 1336 // Clear the _cset_fast_test bitmap in anticipation of adding
1337 1337 // regions to the incremental collection set for the next
1338 1338 // evacuation pause.
1339 1339 clear_cset_fast_test();
1340 1340
1341 1341 init_mutator_alloc_region();
1342 1342
1343 1343 double end = os::elapsedTime();
1344 1344 g1_policy()->record_full_collection_end();
1345 1345
1346 1346 #ifdef TRACESPINNING
1347 1347 ParallelTaskTerminator::print_termination_counts();
1348 1348 #endif
1349 1349
1350 1350 gc_epilogue(true);
1351 1351
1352 1352 // Discard all rset updates
1353 1353 JavaThread::dirty_card_queue_set().abandon_logs();
1354 1354 assert(!G1DeferredRSUpdate
1355 1355 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1356 1356 }
1357 1357
1358 1358 if (g1_policy()->in_young_gc_mode()) {
1359 1359 _young_list->reset_sampled_info();
1360 1360 // At this point there should be no regions in the
1361 1361 // entire heap tagged as young.
1362 1362 assert( check_young_list_empty(true /* check_heap */),
1363 1363 "young list should be empty at this point");
1364 1364 }
1365 1365
1366 1366 // Update the number of full collections that have been completed.
1367 1367 increment_full_collections_completed(false /* concurrent */);
1368 1368
1369 1369 verify_region_sets_optional();
1370 1370
1371 1371 if (PrintHeapAtGC) {
1372 1372 Universe::print_heap_after_gc();
1373 1373 }
1374 1374 g1mm()->update_counters();
1375 1375
1376 1376 return true;
1377 1377 }
1378 1378
1379 1379 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1380 1380 // do_collection() will return whether it succeeded in performing
1381 1381 // the GC. Currently, there is no facility on the
1382 1382 // do_full_collection() API to notify the caller than the collection
1383 1383 // did not succeed (e.g., because it was locked out by the GC
1384 1384 // locker). So, right now, we'll ignore the return value.
1385 1385 bool dummy = do_collection(true, /* explicit_gc */
1386 1386 clear_all_soft_refs,
1387 1387 0 /* word_size */);
1388 1388 }
1389 1389
1390 1390 // This code is mostly copied from TenuredGeneration.
1391 1391 void
1392 1392 G1CollectedHeap::
1393 1393 resize_if_necessary_after_full_collection(size_t word_size) {
1394 1394 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1395 1395
1396 1396 // Include the current allocation, if any, and bytes that will be
1397 1397 // pre-allocated to support collections, as "used".
1398 1398 const size_t used_after_gc = used();
1399 1399 const size_t capacity_after_gc = capacity();
1400 1400 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1401 1401
1402 1402 // This is enforced in arguments.cpp.
1403 1403 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1404 1404 "otherwise the code below doesn't make sense");
1405 1405
1406 1406 // We don't have floating point command-line arguments
1407 1407 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1408 1408 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1409 1409 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1410 1410 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1411 1411
1412 1412 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1413 1413 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1414 1414
1415 1415 // We have to be careful here as these two calculations can overflow
1416 1416 // 32-bit size_t's.
1417 1417 double used_after_gc_d = (double) used_after_gc;
1418 1418 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1419 1419 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1420 1420
1421 1421 // Let's make sure that they are both under the max heap size, which
1422 1422 // by default will make them fit into a size_t.
1423 1423 double desired_capacity_upper_bound = (double) max_heap_size;
1424 1424 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1425 1425 desired_capacity_upper_bound);
1426 1426 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1427 1427 desired_capacity_upper_bound);
1428 1428
1429 1429 // We can now safely turn them into size_t's.
1430 1430 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1431 1431 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1432 1432
1433 1433 // This assert only makes sense here, before we adjust them
1434 1434 // with respect to the min and max heap size.
1435 1435 assert(minimum_desired_capacity <= maximum_desired_capacity,
1436 1436 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1437 1437 "maximum_desired_capacity = "SIZE_FORMAT,
1438 1438 minimum_desired_capacity, maximum_desired_capacity));
1439 1439
1440 1440 // Should not be greater than the heap max size. No need to adjust
1441 1441 // it with respect to the heap min size as it's a lower bound (i.e.,
1442 1442 // we'll try to make the capacity larger than it, not smaller).
1443 1443 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1444 1444 // Should not be less than the heap min size. No need to adjust it
1445 1445 // with respect to the heap max size as it's an upper bound (i.e.,
1446 1446 // we'll try to make the capacity smaller than it, not greater).
1447 1447 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1448 1448
1449 1449 if (PrintGC && Verbose) {
1450 1450 const double free_percentage =
1451 1451 (double) free_after_gc / (double) capacity_after_gc;
1452 1452 gclog_or_tty->print_cr("Computing new size after full GC ");
1453 1453 gclog_or_tty->print_cr(" "
1454 1454 " minimum_free_percentage: %6.2f",
1455 1455 minimum_free_percentage);
1456 1456 gclog_or_tty->print_cr(" "
1457 1457 " maximum_free_percentage: %6.2f",
1458 1458 maximum_free_percentage);
1459 1459 gclog_or_tty->print_cr(" "
1460 1460 " capacity: %6.1fK"
1461 1461 " minimum_desired_capacity: %6.1fK"
1462 1462 " maximum_desired_capacity: %6.1fK",
1463 1463 (double) capacity_after_gc / (double) K,
1464 1464 (double) minimum_desired_capacity / (double) K,
1465 1465 (double) maximum_desired_capacity / (double) K);
1466 1466 gclog_or_tty->print_cr(" "
1467 1467 " free_after_gc: %6.1fK"
1468 1468 " used_after_gc: %6.1fK",
1469 1469 (double) free_after_gc / (double) K,
1470 1470 (double) used_after_gc / (double) K);
1471 1471 gclog_or_tty->print_cr(" "
1472 1472 " free_percentage: %6.2f",
1473 1473 free_percentage);
1474 1474 }
1475 1475 if (capacity_after_gc < minimum_desired_capacity) {
1476 1476 // Don't expand unless it's significant
1477 1477 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1478 1478 if (expand(expand_bytes)) {
1479 1479 if (PrintGC && Verbose) {
1480 1480 gclog_or_tty->print_cr(" "
1481 1481 " expanding:"
1482 1482 " max_heap_size: %6.1fK"
1483 1483 " minimum_desired_capacity: %6.1fK"
1484 1484 " expand_bytes: %6.1fK",
1485 1485 (double) max_heap_size / (double) K,
1486 1486 (double) minimum_desired_capacity / (double) K,
1487 1487 (double) expand_bytes / (double) K);
1488 1488 }
1489 1489 }
1490 1490
1491 1491 // No expansion, now see if we want to shrink
1492 1492 } else if (capacity_after_gc > maximum_desired_capacity) {
1493 1493 // Capacity too large, compute shrinking size
1494 1494 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1495 1495 shrink(shrink_bytes);
1496 1496 if (PrintGC && Verbose) {
1497 1497 gclog_or_tty->print_cr(" "
1498 1498 " shrinking:"
1499 1499 " min_heap_size: %6.1fK"
1500 1500 " maximum_desired_capacity: %6.1fK"
1501 1501 " shrink_bytes: %6.1fK",
1502 1502 (double) min_heap_size / (double) K,
1503 1503 (double) maximum_desired_capacity / (double) K,
1504 1504 (double) shrink_bytes / (double) K);
1505 1505 }
1506 1506 }
1507 1507 }
1508 1508
1509 1509
1510 1510 HeapWord*
1511 1511 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1512 1512 bool* succeeded) {
1513 1513 assert_at_safepoint(true /* should_be_vm_thread */);
1514 1514
1515 1515 *succeeded = true;
1516 1516 // Let's attempt the allocation first.
1517 1517 HeapWord* result =
1518 1518 attempt_allocation_at_safepoint(word_size,
1519 1519 false /* expect_null_mutator_alloc_region */);
1520 1520 if (result != NULL) {
1521 1521 assert(*succeeded, "sanity");
1522 1522 return result;
1523 1523 }
1524 1524
1525 1525 // In a G1 heap, we're supposed to keep allocation from failing by
1526 1526 // incremental pauses. Therefore, at least for now, we'll favor
1527 1527 // expansion over collection. (This might change in the future if we can
1528 1528 // do something smarter than full collection to satisfy a failed alloc.)
1529 1529 result = expand_and_allocate(word_size);
1530 1530 if (result != NULL) {
1531 1531 assert(*succeeded, "sanity");
1532 1532 return result;
1533 1533 }
1534 1534
1535 1535 // Expansion didn't work, we'll try to do a Full GC.
1536 1536 bool gc_succeeded = do_collection(false, /* explicit_gc */
1537 1537 false, /* clear_all_soft_refs */
1538 1538 word_size);
1539 1539 if (!gc_succeeded) {
1540 1540 *succeeded = false;
1541 1541 return NULL;
1542 1542 }
1543 1543
1544 1544 // Retry the allocation
1545 1545 result = attempt_allocation_at_safepoint(word_size,
1546 1546 true /* expect_null_mutator_alloc_region */);
1547 1547 if (result != NULL) {
1548 1548 assert(*succeeded, "sanity");
1549 1549 return result;
1550 1550 }
1551 1551
1552 1552 // Then, try a Full GC that will collect all soft references.
1553 1553 gc_succeeded = do_collection(false, /* explicit_gc */
1554 1554 true, /* clear_all_soft_refs */
1555 1555 word_size);
1556 1556 if (!gc_succeeded) {
1557 1557 *succeeded = false;
1558 1558 return NULL;
1559 1559 }
1560 1560
1561 1561 // Retry the allocation once more
1562 1562 result = attempt_allocation_at_safepoint(word_size,
1563 1563 true /* expect_null_mutator_alloc_region */);
1564 1564 if (result != NULL) {
1565 1565 assert(*succeeded, "sanity");
1566 1566 return result;
1567 1567 }
1568 1568
1569 1569 assert(!collector_policy()->should_clear_all_soft_refs(),
1570 1570 "Flag should have been handled and cleared prior to this point");
1571 1571
1572 1572 // What else? We might try synchronous finalization later. If the total
1573 1573 // space available is large enough for the allocation, then a more
1574 1574 // complete compaction phase than we've tried so far might be
1575 1575 // appropriate.
1576 1576 assert(*succeeded, "sanity");
1577 1577 return NULL;
1578 1578 }
1579 1579
1580 1580 // Attempting to expand the heap sufficiently
1581 1581 // to support an allocation of the given "word_size". If
1582 1582 // successful, perform the allocation and return the address of the
1583 1583 // allocated block, or else "NULL".
1584 1584
1585 1585 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1586 1586 assert_at_safepoint(true /* should_be_vm_thread */);
1587 1587
1588 1588 verify_region_sets_optional();
1589 1589
1590 1590 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1591 1591 if (expand(expand_bytes)) {
1592 1592 verify_region_sets_optional();
1593 1593 return attempt_allocation_at_safepoint(word_size,
1594 1594 false /* expect_null_mutator_alloc_region */);
1595 1595 }
1596 1596 return NULL;
1597 1597 }
1598 1598
1599 1599 bool G1CollectedHeap::expand(size_t expand_bytes) {
1600 1600 size_t old_mem_size = _g1_storage.committed_size();
1601 1601 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1602 1602 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1603 1603 HeapRegion::GrainBytes);
1604 1604
1605 1605 if (Verbose && PrintGC) {
1606 1606 gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK",
1607 1607 old_mem_size/K, aligned_expand_bytes/K);
1608 1608 }
1609 1609
1610 1610 HeapWord* old_end = (HeapWord*)_g1_storage.high();
1611 1611 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1612 1612 if (successful) {
1613 1613 HeapWord* new_end = (HeapWord*)_g1_storage.high();
1614 1614
1615 1615 // Expand the committed region.
1616 1616 _g1_committed.set_end(new_end);
1617 1617
1618 1618 // Tell the cardtable about the expansion.
1619 1619 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1620 1620
1621 1621 // And the offset table as well.
1622 1622 _bot_shared->resize(_g1_committed.word_size());
1623 1623
1624 1624 expand_bytes = aligned_expand_bytes;
1625 1625 HeapWord* base = old_end;
1626 1626
1627 1627 // Create the heap regions for [old_end, new_end)
1628 1628 while (expand_bytes > 0) {
1629 1629 HeapWord* high = base + HeapRegion::GrainWords;
1630 1630
1631 1631 // Create a new HeapRegion.
1632 1632 MemRegion mr(base, high);
1633 1633 bool is_zeroed = !_g1_max_committed.contains(base);
1634 1634 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1635 1635
1636 1636 // Add it to the HeapRegionSeq.
1637 1637 _hrs->insert(hr);
1638 1638 _free_list.add_as_tail(hr);
1639 1639
1640 1640 // And we used up an expansion region to create it.
1641 1641 _expansion_regions--;
1642 1642
1643 1643 expand_bytes -= HeapRegion::GrainBytes;
1644 1644 base += HeapRegion::GrainWords;
1645 1645 }
1646 1646 assert(base == new_end, "sanity");
1647 1647
1648 1648 // Now update max_committed if necessary.
1649 1649 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), new_end));
1650 1650
1651 1651 } else {
1652 1652 // The expansion of the virtual storage space was unsuccessful.
1653 1653 // Let's see if it was because we ran out of swap.
1654 1654 if (G1ExitOnExpansionFailure &&
1655 1655 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1656 1656 // We had head room...
1657 1657 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1658 1658 }
1659 1659 }
1660 1660
1661 1661 if (Verbose && PrintGC) {
1662 1662 size_t new_mem_size = _g1_storage.committed_size();
1663 1663 gclog_or_tty->print_cr("...%s, expanded to %ldK",
1664 1664 (successful ? "Successful" : "Failed"),
1665 1665 new_mem_size/K);
1666 1666 }
1667 1667 return successful;
1668 1668 }
1669 1669
1670 1670 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1671 1671 {
1672 1672 size_t old_mem_size = _g1_storage.committed_size();
1673 1673 size_t aligned_shrink_bytes =
1674 1674 ReservedSpace::page_align_size_down(shrink_bytes);
1675 1675 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1676 1676 HeapRegion::GrainBytes);
1677 1677 size_t num_regions_deleted = 0;
1678 1678 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1679 1679
1680 1680 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1681 1681 if (mr.byte_size() > 0)
1682 1682 _g1_storage.shrink_by(mr.byte_size());
1683 1683 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1684 1684
1685 1685 _g1_committed.set_end(mr.start());
1686 1686 _expansion_regions += num_regions_deleted;
1687 1687
1688 1688 // Tell the cardtable about it.
1689 1689 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1690 1690
1691 1691 // And the offset table as well.
1692 1692 _bot_shared->resize(_g1_committed.word_size());
1693 1693
1694 1694 HeapRegionRemSet::shrink_heap(n_regions());
1695 1695
1696 1696 if (Verbose && PrintGC) {
1697 1697 size_t new_mem_size = _g1_storage.committed_size();
1698 1698 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1699 1699 old_mem_size/K, aligned_shrink_bytes/K,
1700 1700 new_mem_size/K);
1701 1701 }
1702 1702 }
1703 1703
1704 1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705 1705 verify_region_sets_optional();
1706 1706
1707 1707 release_gc_alloc_regions(true /* totally */);
1708 1708 // Instead of tearing down / rebuilding the free lists here, we
1709 1709 // could instead use the remove_all_pending() method on free_list to
1710 1710 // remove only the ones that we need to remove.
1711 1711 tear_down_region_lists(); // We will rebuild them in a moment.
1712 1712 shrink_helper(shrink_bytes);
1713 1713 rebuild_region_lists();
1714 1714
1715 1715 verify_region_sets_optional();
1716 1716 }
1717 1717
1718 1718 // Public methods.
1719 1719
1720 1720 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1721 1721 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1722 1722 #endif // _MSC_VER
1723 1723
1724 1724
1725 1725 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1726 1726 SharedHeap(policy_),
1727 1727 _g1_policy(policy_),
1728 1728 _dirty_card_queue_set(false),
1729 1729 _into_cset_dirty_card_queue_set(false),
1730 1730 _is_alive_closure(this),
1731 1731 _ref_processor(NULL),
1732 1732 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1733 1733 _bot_shared(NULL),
1734 1734 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1735 1735 _evac_failure_scan_stack(NULL) ,
1736 1736 _mark_in_progress(false),
1737 1737 _cg1r(NULL), _summary_bytes_used(0),
1738 1738 _refine_cte_cl(NULL),
1739 1739 _full_collection(false),
1740 1740 _free_list("Master Free List"),
1741 1741 _secondary_free_list("Secondary Free List"),
1742 1742 _humongous_set("Master Humongous Set"),
1743 1743 _free_regions_coming(false),
1744 1744 _young_list(new YoungList(this)),
1745 1745 _gc_time_stamp(0),
1746 1746 _surviving_young_words(NULL),
1747 1747 _full_collections_completed(0),
1748 1748 _in_cset_fast_test(NULL),
1749 1749 _in_cset_fast_test_base(NULL),
1750 1750 _dirty_cards_region_list(NULL) {
1751 1751 _g1h = this; // To catch bugs.
1752 1752 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1753 1753 vm_exit_during_initialization("Failed necessary allocation.");
1754 1754 }
1755 1755
1756 1756 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1757 1757
1758 1758 int n_queues = MAX2((int)ParallelGCThreads, 1);
1759 1759 _task_queues = new RefToScanQueueSet(n_queues);
1760 1760
1761 1761 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1762 1762 assert(n_rem_sets > 0, "Invariant.");
1763 1763
1764 1764 HeapRegionRemSetIterator** iter_arr =
1765 1765 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1766 1766 for (int i = 0; i < n_queues; i++) {
1767 1767 iter_arr[i] = new HeapRegionRemSetIterator();
1768 1768 }
1769 1769 _rem_set_iterator = iter_arr;
1770 1770
1771 1771 for (int i = 0; i < n_queues; i++) {
1772 1772 RefToScanQueue* q = new RefToScanQueue();
1773 1773 q->initialize();
1774 1774 _task_queues->register_queue(i, q);
1775 1775 }
1776 1776
1777 1777 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1778 1778 _gc_alloc_regions[ap] = NULL;
1779 1779 _gc_alloc_region_counts[ap] = 0;
1780 1780 _retained_gc_alloc_regions[ap] = NULL;
1781 1781 // by default, we do not retain a GC alloc region for each ap;
1782 1782 // we'll override this, when appropriate, below
1783 1783 _retain_gc_alloc_region[ap] = false;
1784 1784 }
1785 1785
1786 1786 // We will try to remember the last half-full tenured region we
1787 1787 // allocated to at the end of a collection so that we can re-use it
1788 1788 // during the next collection.
1789 1789 _retain_gc_alloc_region[GCAllocForTenured] = true;
1790 1790
1791 1791 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1792 1792 }
1793 1793
1794 1794 jint G1CollectedHeap::initialize() {
1795 1795 CollectedHeap::pre_initialize();
1796 1796 os::enable_vtime();
1797 1797
1798 1798 // Necessary to satisfy locking discipline assertions.
1799 1799
1800 1800 MutexLocker x(Heap_lock);
1801 1801
1802 1802 // While there are no constraints in the GC code that HeapWordSize
1803 1803 // be any particular value, there are multiple other areas in the
1804 1804 // system which believe this to be true (e.g. oop->object_size in some
1805 1805 // cases incorrectly returns the size in wordSize units rather than
1806 1806 // HeapWordSize).
1807 1807 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1808 1808
1809 1809 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1810 1810 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1811 1811
1812 1812 // Ensure that the sizes are properly aligned.
1813 1813 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1814 1814 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1815 1815
1816 1816 _cg1r = new ConcurrentG1Refine();
1817 1817
1818 1818 // Reserve the maximum.
1819 1819 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1820 1820 // Includes the perm-gen.
1821 1821
1822 1822 const size_t total_reserved = max_byte_size + pgs->max_size();
1823 1823 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1824 1824
1825 1825 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1826 1826 HeapRegion::GrainBytes,
1827 1827 UseLargePages, addr);
1828 1828
1829 1829 if (UseCompressedOops) {
1830 1830 if (addr != NULL && !heap_rs.is_reserved()) {
1831 1831 // Failed to reserve at specified address - the requested memory
1832 1832 // region is taken already, for example, by 'java' launcher.
1833 1833 // Try again to reserver heap higher.
1834 1834 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1835 1835 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1836 1836 UseLargePages, addr);
1837 1837 if (addr != NULL && !heap_rs0.is_reserved()) {
1838 1838 // Failed to reserve at specified address again - give up.
1839 1839 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1840 1840 assert(addr == NULL, "");
1841 1841 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1842 1842 UseLargePages, addr);
1843 1843 heap_rs = heap_rs1;
1844 1844 } else {
1845 1845 heap_rs = heap_rs0;
1846 1846 }
1847 1847 }
1848 1848 }
1849 1849
1850 1850 if (!heap_rs.is_reserved()) {
1851 1851 vm_exit_during_initialization("Could not reserve enough space for object heap");
1852 1852 return JNI_ENOMEM;
1853 1853 }
1854 1854
1855 1855 // It is important to do this in a way such that concurrent readers can't
1856 1856 // temporarily think somethings in the heap. (I've actually seen this
1857 1857 // happen in asserts: DLD.)
1858 1858 _reserved.set_word_size(0);
1859 1859 _reserved.set_start((HeapWord*)heap_rs.base());
1860 1860 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1861 1861
1862 1862 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1863 1863
1864 1864 // Create the gen rem set (and barrier set) for the entire reserved region.
1865 1865 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1866 1866 set_barrier_set(rem_set()->bs());
1867 1867 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1868 1868 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1869 1869 } else {
1870 1870 vm_exit_during_initialization("G1 requires a mod ref bs.");
1871 1871 return JNI_ENOMEM;
1872 1872 }
1873 1873
1874 1874 // Also create a G1 rem set.
1875 1875 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1876 1876 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1877 1877 } else {
1878 1878 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1879 1879 return JNI_ENOMEM;
1880 1880 }
1881 1881
1882 1882 // Carve out the G1 part of the heap.
1883 1883
1884 1884 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1885 1885 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1886 1886 g1_rs.size()/HeapWordSize);
1887 1887 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1888 1888
1889 1889 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1890 1890
1891 1891 _g1_storage.initialize(g1_rs, 0);
1892 1892 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1893 1893 _g1_max_committed = _g1_committed;
1894 1894 _hrs = new HeapRegionSeq(_expansion_regions);
1895 1895 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1896 1896
1897 1897 // 6843694 - ensure that the maximum region index can fit
1898 1898 // in the remembered set structures.
1899 1899 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1900 1900 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1901 1901
1902 1902 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1903 1903 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1904 1904 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1905 1905 "too many cards per region");
1906 1906
1907 1907 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
1908 1908
1909 1909 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1910 1910 heap_word_size(init_byte_size));
1911 1911
1912 1912 _g1h = this;
1913 1913
1914 1914 _in_cset_fast_test_length = max_regions();
1915 1915 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1916 1916
1917 1917 // We're biasing _in_cset_fast_test to avoid subtracting the
1918 1918 // beginning of the heap every time we want to index; basically
1919 1919 // it's the same with what we do with the card table.
1920 1920 _in_cset_fast_test = _in_cset_fast_test_base -
1921 1921 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1922 1922
1923 1923 // Clear the _cset_fast_test bitmap in anticipation of adding
1924 1924 // regions to the incremental collection set for the first
1925 1925 // evacuation pause.
1926 1926 clear_cset_fast_test();
1927 1927
1928 1928 // Create the ConcurrentMark data structure and thread.
1929 1929 // (Must do this late, so that "max_regions" is defined.)
1930 1930 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1931 1931 _cmThread = _cm->cmThread();
1932 1932
1933 1933 // Initialize the from_card cache structure of HeapRegionRemSet.
1934 1934 HeapRegionRemSet::init_heap(max_regions());
1935 1935
1936 1936 // Now expand into the initial heap size.
1937 1937 if (!expand(init_byte_size)) {
1938 1938 vm_exit_during_initialization("Failed to allocate initial heap.");
1939 1939 return JNI_ENOMEM;
1940 1940 }
1941 1941
1942 1942 // Perform any initialization actions delegated to the policy.
1943 1943 g1_policy()->init();
1944 1944
1945 1945 g1_policy()->note_start_of_mark_thread();
1946 1946
1947 1947 _refine_cte_cl =
1948 1948 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1949 1949 g1_rem_set(),
1950 1950 concurrent_g1_refine());
1951 1951 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1952 1952
1953 1953 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1954 1954 SATB_Q_FL_lock,
1955 1955 G1SATBProcessCompletedThreshold,
1956 1956 Shared_SATB_Q_lock);
1957 1957
1958 1958 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1959 1959 DirtyCardQ_FL_lock,
1960 1960 concurrent_g1_refine()->yellow_zone(),
1961 1961 concurrent_g1_refine()->red_zone(),
1962 1962 Shared_DirtyCardQ_lock);
1963 1963
1964 1964 if (G1DeferredRSUpdate) {
1965 1965 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1966 1966 DirtyCardQ_FL_lock,
1967 1967 -1, // never trigger processing
1968 1968 -1, // no limit on length
1969 1969 Shared_DirtyCardQ_lock,
1970 1970 &JavaThread::dirty_card_queue_set());
1971 1971 }
1972 1972
1973 1973 // Initialize the card queue set used to hold cards containing
1974 1974 // references into the collection set.
1975 1975 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
1976 1976 DirtyCardQ_FL_lock,
1977 1977 -1, // never trigger processing
1978 1978 -1, // no limit on length
1979 1979 Shared_DirtyCardQ_lock,
1980 1980 &JavaThread::dirty_card_queue_set());
1981 1981
1982 1982 // In case we're keeping closure specialization stats, initialize those
1983 1983 // counts and that mechanism.
1984 1984 SpecializationStats::clear();
1985 1985
1986 1986 _gc_alloc_region_list = NULL;
1987 1987
1988 1988 // Do later initialization work for concurrent refinement.
1989 1989 _cg1r->init();
1990 1990
1991 1991 // Here we allocate the dummy full region that is required by the
1992 1992 // G1AllocRegion class. If we don't pass an address in the reserved
1993 1993 // space here, lots of asserts fire.
1994 1994 MemRegion mr(_g1_reserved.start(), HeapRegion::GrainWords);
1995 1995 HeapRegion* dummy_region = new HeapRegion(_bot_shared, mr, true);
1996 1996 // We'll re-use the same region whether the alloc region will
1997 1997 // require BOT updates or not and, if it doesn't, then a non-young
1998 1998 // region will complain that it cannot support allocations without
1999 1999 // BOT updates. So we'll tag the dummy region as young to avoid that.
2000 2000 dummy_region->set_young();
2001 2001 // Make sure it's full.
2002 2002 dummy_region->set_top(dummy_region->end());
2003 2003 G1AllocRegion::setup(this, dummy_region);
2004 2004
2005 2005 init_mutator_alloc_region();
2006 2006
2007 2007 // Do create of the monitoring and management support so that
2008 2008 // values in the heap have been properly initialized.
2009 2009 _g1mm = new G1MonitoringSupport(this, &_g1_storage);
2010 2010
2011 2011 return JNI_OK;
2012 2012 }
2013 2013
2014 2014 void G1CollectedHeap::ref_processing_init() {
2015 2015 // Reference processing in G1 currently works as follows:
2016 2016 //
2017 2017 // * There is only one reference processor instance that
2018 2018 // 'spans' the entire heap. It is created by the code
2019 2019 // below.
2020 2020 // * Reference discovery is not enabled during an incremental
2021 2021 // pause (see 6484982).
2022 2022 // * Discoverered refs are not enqueued nor are they processed
2023 2023 // during an incremental pause (see 6484982).
2024 2024 // * Reference discovery is enabled at initial marking.
2025 2025 // * Reference discovery is disabled and the discovered
2026 2026 // references processed etc during remarking.
2027 2027 // * Reference discovery is MT (see below).
2028 2028 // * Reference discovery requires a barrier (see below).
2029 2029 // * Reference processing is currently not MT (see 6608385).
2030 2030 // * A full GC enables (non-MT) reference discovery and
2031 2031 // processes any discovered references.
2032 2032
2033 2033 SharedHeap::ref_processing_init();
2034 2034 MemRegion mr = reserved_region();
2035 2035 _ref_processor =
2036 2036 new ReferenceProcessor(mr, // span
2037 2037 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
2038 2038 (int) ParallelGCThreads, // degree of mt processing
2039 2039 ParallelGCThreads > 1 || ConcGCThreads > 1, // mt discovery
2040 2040 (int) MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
2041 2041 false, // Reference discovery is not atomic
2042 2042 &_is_alive_closure, // is alive closure for efficiency
2043 2043 true); // Setting next fields of discovered
2044 2044 // lists requires a barrier.
2045 2045 }
2046 2046
2047 2047 size_t G1CollectedHeap::capacity() const {
2048 2048 return _g1_committed.byte_size();
2049 2049 }
2050 2050
2051 2051 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2052 2052 DirtyCardQueue* into_cset_dcq,
2053 2053 bool concurrent,
2054 2054 int worker_i) {
2055 2055 // Clean cards in the hot card cache
2056 2056 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2057 2057
2058 2058 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2059 2059 int n_completed_buffers = 0;
2060 2060 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2061 2061 n_completed_buffers++;
2062 2062 }
2063 2063 g1_policy()->record_update_rs_processed_buffers(worker_i,
2064 2064 (double) n_completed_buffers);
2065 2065 dcqs.clear_n_completed_buffers();
2066 2066 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2067 2067 }
2068 2068
2069 2069
2070 2070 // Computes the sum of the storage used by the various regions.
2071 2071
2072 2072 size_t G1CollectedHeap::used() const {
2073 2073 assert(Heap_lock->owner() != NULL,
2074 2074 "Should be owned on this thread's behalf.");
2075 2075 size_t result = _summary_bytes_used;
2076 2076 // Read only once in case it is set to NULL concurrently
2077 2077 HeapRegion* hr = _mutator_alloc_region.get();
2078 2078 if (hr != NULL)
2079 2079 result += hr->used();
2080 2080 return result;
2081 2081 }
2082 2082
2083 2083 size_t G1CollectedHeap::used_unlocked() const {
2084 2084 size_t result = _summary_bytes_used;
2085 2085 return result;
2086 2086 }
2087 2087
2088 2088 class SumUsedClosure: public HeapRegionClosure {
2089 2089 size_t _used;
2090 2090 public:
2091 2091 SumUsedClosure() : _used(0) {}
2092 2092 bool doHeapRegion(HeapRegion* r) {
2093 2093 if (!r->continuesHumongous()) {
2094 2094 _used += r->used();
2095 2095 }
2096 2096 return false;
2097 2097 }
2098 2098 size_t result() { return _used; }
2099 2099 };
2100 2100
2101 2101 size_t G1CollectedHeap::recalculate_used() const {
2102 2102 SumUsedClosure blk;
2103 2103 _hrs->iterate(&blk);
2104 2104 return blk.result();
2105 2105 }
2106 2106
2107 2107 #ifndef PRODUCT
2108 2108 class SumUsedRegionsClosure: public HeapRegionClosure {
2109 2109 size_t _num;
2110 2110 public:
2111 2111 SumUsedRegionsClosure() : _num(0) {}
2112 2112 bool doHeapRegion(HeapRegion* r) {
2113 2113 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
2114 2114 _num += 1;
2115 2115 }
2116 2116 return false;
2117 2117 }
2118 2118 size_t result() { return _num; }
2119 2119 };
2120 2120
2121 2121 size_t G1CollectedHeap::recalculate_used_regions() const {
2122 2122 SumUsedRegionsClosure blk;
2123 2123 _hrs->iterate(&blk);
2124 2124 return blk.result();
2125 2125 }
2126 2126 #endif // PRODUCT
2127 2127
2128 2128 size_t G1CollectedHeap::unsafe_max_alloc() {
2129 2129 if (free_regions() > 0) return HeapRegion::GrainBytes;
2130 2130 // otherwise, is there space in the current allocation region?
2131 2131
2132 2132 // We need to store the current allocation region in a local variable
2133 2133 // here. The problem is that this method doesn't take any locks and
2134 2134 // there may be other threads which overwrite the current allocation
2135 2135 // region field. attempt_allocation(), for example, sets it to NULL
2136 2136 // and this can happen *after* the NULL check here but before the call
2137 2137 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2138 2138 // to be a problem in the optimized build, since the two loads of the
2139 2139 // current allocation region field are optimized away.
2140 2140 HeapRegion* hr = _mutator_alloc_region.get();
2141 2141 if (hr == NULL) {
2142 2142 return 0;
2143 2143 }
2144 2144 return hr->free();
2145 2145 }
2146 2146
2147 2147 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2148 2148 return
2149 2149 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2150 2150 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2151 2151 }
2152 2152
2153 2153 #ifndef PRODUCT
2154 2154 void G1CollectedHeap::allocate_dummy_regions() {
2155 2155 // Let's fill up most of the region
2156 2156 size_t word_size = HeapRegion::GrainWords - 1024;
2157 2157 // And as a result the region we'll allocate will be humongous.
2158 2158 guarantee(isHumongous(word_size), "sanity");
2159 2159
2160 2160 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2161 2161 // Let's use the existing mechanism for the allocation
2162 2162 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2163 2163 if (dummy_obj != NULL) {
2164 2164 MemRegion mr(dummy_obj, word_size);
2165 2165 CollectedHeap::fill_with_object(mr);
2166 2166 } else {
2167 2167 // If we can't allocate once, we probably cannot allocate
2168 2168 // again. Let's get out of the loop.
2169 2169 break;
2170 2170 }
2171 2171 }
2172 2172 }
2173 2173 #endif // !PRODUCT
2174 2174
2175 2175 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2176 2176 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2177 2177
2178 2178 // We assume that if concurrent == true, then the caller is a
2179 2179 // concurrent thread that was joined the Suspendible Thread
2180 2180 // Set. If there's ever a cheap way to check this, we should add an
2181 2181 // assert here.
2182 2182
2183 2183 // We have already incremented _total_full_collections at the start
2184 2184 // of the GC, so total_full_collections() represents how many full
2185 2185 // collections have been started.
2186 2186 unsigned int full_collections_started = total_full_collections();
2187 2187
2188 2188 // Given that this method is called at the end of a Full GC or of a
2189 2189 // concurrent cycle, and those can be nested (i.e., a Full GC can
2190 2190 // interrupt a concurrent cycle), the number of full collections
2191 2191 // completed should be either one (in the case where there was no
2192 2192 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2193 2193 // behind the number of full collections started.
2194 2194
2195 2195 // This is the case for the inner caller, i.e. a Full GC.
2196 2196 assert(concurrent ||
2197 2197 (full_collections_started == _full_collections_completed + 1) ||
2198 2198 (full_collections_started == _full_collections_completed + 2),
2199 2199 err_msg("for inner caller (Full GC): full_collections_started = %u "
2200 2200 "is inconsistent with _full_collections_completed = %u",
2201 2201 full_collections_started, _full_collections_completed));
2202 2202
2203 2203 // This is the case for the outer caller, i.e. the concurrent cycle.
2204 2204 assert(!concurrent ||
2205 2205 (full_collections_started == _full_collections_completed + 1),
2206 2206 err_msg("for outer caller (concurrent cycle): "
2207 2207 "full_collections_started = %u "
2208 2208 "is inconsistent with _full_collections_completed = %u",
2209 2209 full_collections_started, _full_collections_completed));
2210 2210
2211 2211 _full_collections_completed += 1;
2212 2212
2213 2213 // We need to clear the "in_progress" flag in the CM thread before
2214 2214 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2215 2215 // is set) so that if a waiter requests another System.gc() it doesn't
2216 2216 // incorrectly see that a marking cyle is still in progress.
2217 2217 if (concurrent) {
2218 2218 _cmThread->clear_in_progress();
2219 2219 }
2220 2220
2221 2221 // This notify_all() will ensure that a thread that called
2222 2222 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2223 2223 // and it's waiting for a full GC to finish will be woken up. It is
2224 2224 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2225 2225 FullGCCount_lock->notify_all();
2226 2226 }
2227 2227
2228 2228 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2229 2229 assert_at_safepoint(true /* should_be_vm_thread */);
2230 2230 GCCauseSetter gcs(this, cause);
2231 2231 switch (cause) {
2232 2232 case GCCause::_heap_inspection:
2233 2233 case GCCause::_heap_dump: {
2234 2234 HandleMark hm;
2235 2235 do_full_collection(false); // don't clear all soft refs
2236 2236 break;
2237 2237 }
2238 2238 default: // XXX FIX ME
2239 2239 ShouldNotReachHere(); // Unexpected use of this function
2240 2240 }
2241 2241 }
2242 2242
2243 2243 void G1CollectedHeap::collect(GCCause::Cause cause) {
2244 2244 // The caller doesn't have the Heap_lock
2245 2245 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2246 2246
2247 2247 unsigned int gc_count_before;
2248 2248 unsigned int full_gc_count_before;
2249 2249 {
2250 2250 MutexLocker ml(Heap_lock);
2251 2251
2252 2252 // Read the GC count while holding the Heap_lock
2253 2253 gc_count_before = SharedHeap::heap()->total_collections();
2254 2254 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2255 2255 }
2256 2256
2257 2257 if (should_do_concurrent_full_gc(cause)) {
2258 2258 // Schedule an initial-mark evacuation pause that will start a
2259 2259 // concurrent cycle. We're setting word_size to 0 which means that
2260 2260 // we are not requesting a post-GC allocation.
2261 2261 VM_G1IncCollectionPause op(gc_count_before,
2262 2262 0, /* word_size */
2263 2263 true, /* should_initiate_conc_mark */
2264 2264 g1_policy()->max_pause_time_ms(),
2265 2265 cause);
2266 2266 VMThread::execute(&op);
2267 2267 } else {
2268 2268 if (cause == GCCause::_gc_locker
2269 2269 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2270 2270
2271 2271 // Schedule a standard evacuation pause. We're setting word_size
2272 2272 // to 0 which means that we are not requesting a post-GC allocation.
2273 2273 VM_G1IncCollectionPause op(gc_count_before,
2274 2274 0, /* word_size */
2275 2275 false, /* should_initiate_conc_mark */
2276 2276 g1_policy()->max_pause_time_ms(),
2277 2277 cause);
2278 2278 VMThread::execute(&op);
2279 2279 } else {
2280 2280 // Schedule a Full GC.
2281 2281 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2282 2282 VMThread::execute(&op);
2283 2283 }
2284 2284 }
2285 2285 }
2286 2286
2287 2287 bool G1CollectedHeap::is_in(const void* p) const {
2288 2288 if (_g1_committed.contains(p)) {
2289 2289 HeapRegion* hr = _hrs->addr_to_region(p);
2290 2290 return hr->is_in(p);
2291 2291 } else {
2292 2292 return _perm_gen->as_gen()->is_in(p);
2293 2293 }
2294 2294 }
2295 2295
2296 2296 // Iteration functions.
2297 2297
2298 2298 // Iterates an OopClosure over all ref-containing fields of objects
2299 2299 // within a HeapRegion.
2300 2300
2301 2301 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2302 2302 MemRegion _mr;
2303 2303 OopClosure* _cl;
2304 2304 public:
2305 2305 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2306 2306 : _mr(mr), _cl(cl) {}
2307 2307 bool doHeapRegion(HeapRegion* r) {
2308 2308 if (! r->continuesHumongous()) {
2309 2309 r->oop_iterate(_cl);
2310 2310 }
2311 2311 return false;
2312 2312 }
2313 2313 };
2314 2314
2315 2315 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2316 2316 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2317 2317 _hrs->iterate(&blk);
2318 2318 if (do_perm) {
2319 2319 perm_gen()->oop_iterate(cl);
2320 2320 }
2321 2321 }
2322 2322
2323 2323 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2324 2324 IterateOopClosureRegionClosure blk(mr, cl);
2325 2325 _hrs->iterate(&blk);
2326 2326 if (do_perm) {
2327 2327 perm_gen()->oop_iterate(cl);
2328 2328 }
2329 2329 }
2330 2330
2331 2331 // Iterates an ObjectClosure over all objects within a HeapRegion.
2332 2332
2333 2333 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2334 2334 ObjectClosure* _cl;
2335 2335 public:
2336 2336 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2337 2337 bool doHeapRegion(HeapRegion* r) {
2338 2338 if (! r->continuesHumongous()) {
2339 2339 r->object_iterate(_cl);
2340 2340 }
2341 2341 return false;
2342 2342 }
2343 2343 };
2344 2344
2345 2345 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2346 2346 IterateObjectClosureRegionClosure blk(cl);
2347 2347 _hrs->iterate(&blk);
2348 2348 if (do_perm) {
2349 2349 perm_gen()->object_iterate(cl);
2350 2350 }
2351 2351 }
2352 2352
2353 2353 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2354 2354 // FIXME: is this right?
2355 2355 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2356 2356 }
2357 2357
2358 2358 // Calls a SpaceClosure on a HeapRegion.
2359 2359
2360 2360 class SpaceClosureRegionClosure: public HeapRegionClosure {
2361 2361 SpaceClosure* _cl;
2362 2362 public:
2363 2363 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2364 2364 bool doHeapRegion(HeapRegion* r) {
2365 2365 _cl->do_space(r);
2366 2366 return false;
2367 2367 }
2368 2368 };
2369 2369
2370 2370 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2371 2371 SpaceClosureRegionClosure blk(cl);
2372 2372 _hrs->iterate(&blk);
2373 2373 }
2374 2374
2375 2375 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
2376 2376 _hrs->iterate(cl);
2377 2377 }
2378 2378
2379 2379 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2380 2380 HeapRegionClosure* cl) {
2381 2381 _hrs->iterate_from(r, cl);
2382 2382 }
2383 2383
2384 2384 void
2385 2385 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
2386 2386 _hrs->iterate_from(idx, cl);
2387 2387 }
2388 2388
2389 2389 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
2390 2390
2391 2391 void
2392 2392 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2393 2393 int worker,
2394 2394 jint claim_value) {
2395 2395 const size_t regions = n_regions();
2396 2396 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2397 2397 // try to spread out the starting points of the workers
2398 2398 const size_t start_index = regions / worker_num * (size_t) worker;
2399 2399
2400 2400 // each worker will actually look at all regions
2401 2401 for (size_t count = 0; count < regions; ++count) {
2402 2402 const size_t index = (start_index + count) % regions;
2403 2403 assert(0 <= index && index < regions, "sanity");
2404 2404 HeapRegion* r = region_at(index);
2405 2405 // we'll ignore "continues humongous" regions (we'll process them
2406 2406 // when we come across their corresponding "start humongous"
2407 2407 // region) and regions already claimed
2408 2408 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2409 2409 continue;
2410 2410 }
2411 2411 // OK, try to claim it
2412 2412 if (r->claimHeapRegion(claim_value)) {
2413 2413 // success!
2414 2414 assert(!r->continuesHumongous(), "sanity");
2415 2415 if (r->startsHumongous()) {
2416 2416 // If the region is "starts humongous" we'll iterate over its
2417 2417 // "continues humongous" first; in fact we'll do them
2418 2418 // first. The order is important. In on case, calling the
2419 2419 // closure on the "starts humongous" region might de-allocate
2420 2420 // and clear all its "continues humongous" regions and, as a
2421 2421 // result, we might end up processing them twice. So, we'll do
2422 2422 // them first (notice: most closures will ignore them anyway) and
2423 2423 // then we'll do the "starts humongous" region.
2424 2424 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2425 2425 HeapRegion* chr = region_at(ch_index);
2426 2426
2427 2427 // if the region has already been claimed or it's not
2428 2428 // "continues humongous" we're done
2429 2429 if (chr->claim_value() == claim_value ||
2430 2430 !chr->continuesHumongous()) {
2431 2431 break;
2432 2432 }
2433 2433
2434 2434 // Noone should have claimed it directly. We can given
2435 2435 // that we claimed its "starts humongous" region.
2436 2436 assert(chr->claim_value() != claim_value, "sanity");
2437 2437 assert(chr->humongous_start_region() == r, "sanity");
2438 2438
2439 2439 if (chr->claimHeapRegion(claim_value)) {
2440 2440 // we should always be able to claim it; noone else should
2441 2441 // be trying to claim this region
2442 2442
2443 2443 bool res2 = cl->doHeapRegion(chr);
2444 2444 assert(!res2, "Should not abort");
2445 2445
2446 2446 // Right now, this holds (i.e., no closure that actually
2447 2447 // does something with "continues humongous" regions
2448 2448 // clears them). We might have to weaken it in the future,
2449 2449 // but let's leave these two asserts here for extra safety.
2450 2450 assert(chr->continuesHumongous(), "should still be the case");
2451 2451 assert(chr->humongous_start_region() == r, "sanity");
2452 2452 } else {
2453 2453 guarantee(false, "we should not reach here");
2454 2454 }
2455 2455 }
2456 2456 }
2457 2457
2458 2458 assert(!r->continuesHumongous(), "sanity");
2459 2459 bool res = cl->doHeapRegion(r);
2460 2460 assert(!res, "Should not abort");
2461 2461 }
2462 2462 }
2463 2463 }
2464 2464
2465 2465 class ResetClaimValuesClosure: public HeapRegionClosure {
2466 2466 public:
2467 2467 bool doHeapRegion(HeapRegion* r) {
2468 2468 r->set_claim_value(HeapRegion::InitialClaimValue);
2469 2469 return false;
2470 2470 }
2471 2471 };
2472 2472
2473 2473 void
2474 2474 G1CollectedHeap::reset_heap_region_claim_values() {
2475 2475 ResetClaimValuesClosure blk;
2476 2476 heap_region_iterate(&blk);
2477 2477 }
2478 2478
2479 2479 #ifdef ASSERT
2480 2480 // This checks whether all regions in the heap have the correct claim
2481 2481 // value. I also piggy-backed on this a check to ensure that the
2482 2482 // humongous_start_region() information on "continues humongous"
2483 2483 // regions is correct.
2484 2484
2485 2485 class CheckClaimValuesClosure : public HeapRegionClosure {
2486 2486 private:
2487 2487 jint _claim_value;
2488 2488 size_t _failures;
2489 2489 HeapRegion* _sh_region;
2490 2490 public:
2491 2491 CheckClaimValuesClosure(jint claim_value) :
2492 2492 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2493 2493 bool doHeapRegion(HeapRegion* r) {
2494 2494 if (r->claim_value() != _claim_value) {
2495 2495 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2496 2496 "claim value = %d, should be %d",
2497 2497 r->bottom(), r->end(), r->claim_value(),
2498 2498 _claim_value);
2499 2499 ++_failures;
2500 2500 }
2501 2501 if (!r->isHumongous()) {
2502 2502 _sh_region = NULL;
2503 2503 } else if (r->startsHumongous()) {
2504 2504 _sh_region = r;
2505 2505 } else if (r->continuesHumongous()) {
2506 2506 if (r->humongous_start_region() != _sh_region) {
2507 2507 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2508 2508 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2509 2509 r->bottom(), r->end(),
2510 2510 r->humongous_start_region(),
2511 2511 _sh_region);
2512 2512 ++_failures;
2513 2513 }
2514 2514 }
2515 2515 return false;
2516 2516 }
2517 2517 size_t failures() {
2518 2518 return _failures;
2519 2519 }
2520 2520 };
2521 2521
2522 2522 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2523 2523 CheckClaimValuesClosure cl(claim_value);
2524 2524 heap_region_iterate(&cl);
2525 2525 return cl.failures() == 0;
2526 2526 }
2527 2527 #endif // ASSERT
2528 2528
2529 2529 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2530 2530 HeapRegion* r = g1_policy()->collection_set();
2531 2531 while (r != NULL) {
2532 2532 HeapRegion* next = r->next_in_collection_set();
2533 2533 if (cl->doHeapRegion(r)) {
2534 2534 cl->incomplete();
2535 2535 return;
2536 2536 }
2537 2537 r = next;
2538 2538 }
2539 2539 }
2540 2540
2541 2541 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2542 2542 HeapRegionClosure *cl) {
2543 2543 if (r == NULL) {
2544 2544 // The CSet is empty so there's nothing to do.
2545 2545 return;
2546 2546 }
2547 2547
2548 2548 assert(r->in_collection_set(),
2549 2549 "Start region must be a member of the collection set.");
2550 2550 HeapRegion* cur = r;
2551 2551 while (cur != NULL) {
2552 2552 HeapRegion* next = cur->next_in_collection_set();
2553 2553 if (cl->doHeapRegion(cur) && false) {
2554 2554 cl->incomplete();
2555 2555 return;
2556 2556 }
2557 2557 cur = next;
2558 2558 }
2559 2559 cur = g1_policy()->collection_set();
2560 2560 while (cur != r) {
2561 2561 HeapRegion* next = cur->next_in_collection_set();
2562 2562 if (cl->doHeapRegion(cur) && false) {
2563 2563 cl->incomplete();
2564 2564 return;
2565 2565 }
2566 2566 cur = next;
2567 2567 }
2568 2568 }
2569 2569
2570 2570 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2571 2571 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2572 2572 }
2573 2573
2574 2574
2575 2575 Space* G1CollectedHeap::space_containing(const void* addr) const {
2576 2576 Space* res = heap_region_containing(addr);
2577 2577 if (res == NULL)
2578 2578 res = perm_gen()->space_containing(addr);
2579 2579 return res;
2580 2580 }
2581 2581
2582 2582 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2583 2583 Space* sp = space_containing(addr);
2584 2584 if (sp != NULL) {
2585 2585 return sp->block_start(addr);
2586 2586 }
2587 2587 return NULL;
2588 2588 }
2589 2589
2590 2590 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2591 2591 Space* sp = space_containing(addr);
2592 2592 assert(sp != NULL, "block_size of address outside of heap");
2593 2593 return sp->block_size(addr);
2594 2594 }
2595 2595
2596 2596 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2597 2597 Space* sp = space_containing(addr);
2598 2598 return sp->block_is_obj(addr);
2599 2599 }
2600 2600
2601 2601 bool G1CollectedHeap::supports_tlab_allocation() const {
2602 2602 return true;
2603 2603 }
2604 2604
2605 2605 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2606 2606 return HeapRegion::GrainBytes;
2607 2607 }
2608 2608
2609 2609 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2610 2610 // Return the remaining space in the cur alloc region, but not less than
2611 2611 // the min TLAB size.
2612 2612
2613 2613 // Also, this value can be at most the humongous object threshold,
2614 2614 // since we can't allow tlabs to grow big enough to accomodate
2615 2615 // humongous objects.
2616 2616
2617 2617 HeapRegion* hr = _mutator_alloc_region.get();
2618 2618 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2619 2619 if (hr == NULL) {
2620 2620 return max_tlab_size;
2621 2621 } else {
2622 2622 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2623 2623 }
2624 2624 }
2625 2625
2626 2626 size_t G1CollectedHeap::large_typearray_limit() {
2627 2627 // FIXME
2628 2628 return HeapRegion::GrainBytes/HeapWordSize;
2629 2629 }
2630 2630
2631 2631 size_t G1CollectedHeap::max_capacity() const {
2632 2632 return _g1_reserved.byte_size();
2633 2633 }
2634 2634
2635 2635 jlong G1CollectedHeap::millis_since_last_gc() {
2636 2636 // assert(false, "NYI");
2637 2637 return 0;
2638 2638 }
2639 2639
2640 2640 void G1CollectedHeap::prepare_for_verify() {
2641 2641 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2642 2642 ensure_parsability(false);
2643 2643 }
2644 2644 g1_rem_set()->prepare_for_verify();
2645 2645 }
2646 2646
2647 2647 class VerifyLivenessOopClosure: public OopClosure {
2648 2648 G1CollectedHeap* g1h;
2649 2649 public:
2650 2650 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2651 2651 g1h = _g1h;
2652 2652 }
2653 2653 void do_oop(narrowOop *p) { do_oop_work(p); }
2654 2654 void do_oop( oop *p) { do_oop_work(p); }
2655 2655
2656 2656 template <class T> void do_oop_work(T *p) {
2657 2657 oop obj = oopDesc::load_decode_heap_oop(p);
2658 2658 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2659 2659 "Dead object referenced by a not dead object");
2660 2660 }
2661 2661 };
2662 2662
2663 2663 class VerifyObjsInRegionClosure: public ObjectClosure {
2664 2664 private:
2665 2665 G1CollectedHeap* _g1h;
2666 2666 size_t _live_bytes;
2667 2667 HeapRegion *_hr;
2668 2668 bool _use_prev_marking;
2669 2669 public:
2670 2670 // use_prev_marking == true -> use "prev" marking information,
2671 2671 // use_prev_marking == false -> use "next" marking information
2672 2672 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2673 2673 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2674 2674 _g1h = G1CollectedHeap::heap();
2675 2675 }
2676 2676 void do_object(oop o) {
2677 2677 VerifyLivenessOopClosure isLive(_g1h);
2678 2678 assert(o != NULL, "Huh?");
2679 2679 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2680 2680 o->oop_iterate(&isLive);
2681 2681 if (!_hr->obj_allocated_since_prev_marking(o)) {
2682 2682 size_t obj_size = o->size(); // Make sure we don't overflow
2683 2683 _live_bytes += (obj_size * HeapWordSize);
2684 2684 }
2685 2685 }
2686 2686 }
2687 2687 size_t live_bytes() { return _live_bytes; }
2688 2688 };
2689 2689
2690 2690 class PrintObjsInRegionClosure : public ObjectClosure {
2691 2691 HeapRegion *_hr;
2692 2692 G1CollectedHeap *_g1;
2693 2693 public:
2694 2694 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2695 2695 _g1 = G1CollectedHeap::heap();
2696 2696 };
2697 2697
2698 2698 void do_object(oop o) {
2699 2699 if (o != NULL) {
2700 2700 HeapWord *start = (HeapWord *) o;
2701 2701 size_t word_sz = o->size();
2702 2702 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2703 2703 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2704 2704 (void*) o, word_sz,
2705 2705 _g1->isMarkedPrev(o),
2706 2706 _g1->isMarkedNext(o),
2707 2707 _hr->obj_allocated_since_prev_marking(o));
2708 2708 HeapWord *end = start + word_sz;
2709 2709 HeapWord *cur;
2710 2710 int *val;
2711 2711 for (cur = start; cur < end; cur++) {
2712 2712 val = (int *) cur;
2713 2713 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2714 2714 }
2715 2715 }
2716 2716 }
2717 2717 };
2718 2718
2719 2719 class VerifyRegionClosure: public HeapRegionClosure {
2720 2720 private:
2721 2721 bool _allow_dirty;
2722 2722 bool _par;
2723 2723 bool _use_prev_marking;
2724 2724 bool _failures;
2725 2725 public:
2726 2726 // use_prev_marking == true -> use "prev" marking information,
2727 2727 // use_prev_marking == false -> use "next" marking information
2728 2728 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2729 2729 : _allow_dirty(allow_dirty),
2730 2730 _par(par),
2731 2731 _use_prev_marking(use_prev_marking),
2732 2732 _failures(false) {}
2733 2733
2734 2734 bool failures() {
2735 2735 return _failures;
2736 2736 }
2737 2737
2738 2738 bool doHeapRegion(HeapRegion* r) {
2739 2739 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2740 2740 "Should be unclaimed at verify points.");
2741 2741 if (!r->continuesHumongous()) {
2742 2742 bool failures = false;
2743 2743 r->verify(_allow_dirty, _use_prev_marking, &failures);
2744 2744 if (failures) {
2745 2745 _failures = true;
2746 2746 } else {
2747 2747 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2748 2748 r->object_iterate(¬_dead_yet_cl);
2749 2749 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2750 2750 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2751 2751 "max_live_bytes "SIZE_FORMAT" "
2752 2752 "< calculated "SIZE_FORMAT,
2753 2753 r->bottom(), r->end(),
2754 2754 r->max_live_bytes(),
2755 2755 not_dead_yet_cl.live_bytes());
2756 2756 _failures = true;
2757 2757 }
2758 2758 }
2759 2759 }
2760 2760 return false; // stop the region iteration if we hit a failure
2761 2761 }
2762 2762 };
2763 2763
2764 2764 class VerifyRootsClosure: public OopsInGenClosure {
2765 2765 private:
2766 2766 G1CollectedHeap* _g1h;
2767 2767 bool _use_prev_marking;
2768 2768 bool _failures;
2769 2769 public:
2770 2770 // use_prev_marking == true -> use "prev" marking information,
2771 2771 // use_prev_marking == false -> use "next" marking information
2772 2772 VerifyRootsClosure(bool use_prev_marking) :
2773 2773 _g1h(G1CollectedHeap::heap()),
2774 2774 _use_prev_marking(use_prev_marking),
2775 2775 _failures(false) { }
2776 2776
2777 2777 bool failures() { return _failures; }
2778 2778
2779 2779 template <class T> void do_oop_nv(T* p) {
2780 2780 T heap_oop = oopDesc::load_heap_oop(p);
2781 2781 if (!oopDesc::is_null(heap_oop)) {
2782 2782 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2783 2783 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2784 2784 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2785 2785 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2786 2786 obj->print_on(gclog_or_tty);
2787 2787 _failures = true;
2788 2788 }
2789 2789 }
2790 2790 }
2791 2791
2792 2792 void do_oop(oop* p) { do_oop_nv(p); }
2793 2793 void do_oop(narrowOop* p) { do_oop_nv(p); }
2794 2794 };
2795 2795
2796 2796 // This is the task used for parallel heap verification.
2797 2797
2798 2798 class G1ParVerifyTask: public AbstractGangTask {
2799 2799 private:
2800 2800 G1CollectedHeap* _g1h;
2801 2801 bool _allow_dirty;
2802 2802 bool _use_prev_marking;
2803 2803 bool _failures;
2804 2804
2805 2805 public:
2806 2806 // use_prev_marking == true -> use "prev" marking information,
2807 2807 // use_prev_marking == false -> use "next" marking information
2808 2808 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2809 2809 bool use_prev_marking) :
2810 2810 AbstractGangTask("Parallel verify task"),
2811 2811 _g1h(g1h),
2812 2812 _allow_dirty(allow_dirty),
2813 2813 _use_prev_marking(use_prev_marking),
2814 2814 _failures(false) { }
2815 2815
2816 2816 bool failures() {
2817 2817 return _failures;
2818 2818 }
2819 2819
2820 2820 void work(int worker_i) {
2821 2821 HandleMark hm;
2822 2822 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2823 2823 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2824 2824 HeapRegion::ParVerifyClaimValue);
2825 2825 if (blk.failures()) {
2826 2826 _failures = true;
2827 2827 }
2828 2828 }
2829 2829 };
2830 2830
2831 2831 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2832 2832 verify(allow_dirty, silent, /* use_prev_marking */ true);
2833 2833 }
2834 2834
2835 2835 void G1CollectedHeap::verify(bool allow_dirty,
2836 2836 bool silent,
2837 2837 bool use_prev_marking) {
2838 2838 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2839 2839 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
2840 2840 VerifyRootsClosure rootsCl(use_prev_marking);
2841 2841 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2842 2842 // We apply the relevant closures to all the oops in the
2843 2843 // system dictionary, the string table and the code cache.
2844 2844 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
2845 2845 process_strong_roots(true, // activate StrongRootsScope
2846 2846 true, // we set "collecting perm gen" to true,
2847 2847 // so we don't reset the dirty cards in the perm gen.
2848 2848 SharedHeap::ScanningOption(so), // roots scanning options
2849 2849 &rootsCl,
2850 2850 &blobsCl,
2851 2851 &rootsCl);
2852 2852 // Since we used "collecting_perm_gen" == true above, we will not have
2853 2853 // checked the refs from perm into the G1-collected heap. We check those
2854 2854 // references explicitly below. Whether the relevant cards are dirty
2855 2855 // is checked further below in the rem set verification.
2856 2856 if (!silent) { gclog_or_tty->print("Permgen roots "); }
2857 2857 perm_gen()->oop_iterate(&rootsCl);
2858 2858 bool failures = rootsCl.failures();
2859 2859 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
2860 2860 verify_region_sets();
2861 2861 if (!silent) { gclog_or_tty->print("HeapRegions "); }
2862 2862 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2863 2863 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2864 2864 "sanity check");
2865 2865
2866 2866 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2867 2867 int n_workers = workers()->total_workers();
2868 2868 set_par_threads(n_workers);
2869 2869 workers()->run_task(&task);
2870 2870 set_par_threads(0);
2871 2871 if (task.failures()) {
2872 2872 failures = true;
2873 2873 }
2874 2874
2875 2875 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2876 2876 "sanity check");
2877 2877
2878 2878 reset_heap_region_claim_values();
2879 2879
2880 2880 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2881 2881 "sanity check");
2882 2882 } else {
2883 2883 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2884 2884 _hrs->iterate(&blk);
2885 2885 if (blk.failures()) {
2886 2886 failures = true;
2887 2887 }
2888 2888 }
2889 2889 if (!silent) gclog_or_tty->print("RemSet ");
2890 2890 rem_set()->verify();
2891 2891
2892 2892 if (failures) {
2893 2893 gclog_or_tty->print_cr("Heap:");
2894 2894 print_on(gclog_or_tty, true /* extended */);
2895 2895 gclog_or_tty->print_cr("");
2896 2896 #ifndef PRODUCT
2897 2897 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2898 2898 concurrent_mark()->print_reachable("at-verification-failure",
2899 2899 use_prev_marking, false /* all */);
2900 2900 }
2901 2901 #endif
2902 2902 gclog_or_tty->flush();
2903 2903 }
2904 2904 guarantee(!failures, "there should not have been any failures");
2905 2905 } else {
2906 2906 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2907 2907 }
2908 2908 }
2909 2909
2910 2910 class PrintRegionClosure: public HeapRegionClosure {
2911 2911 outputStream* _st;
2912 2912 public:
2913 2913 PrintRegionClosure(outputStream* st) : _st(st) {}
2914 2914 bool doHeapRegion(HeapRegion* r) {
2915 2915 r->print_on(_st);
2916 2916 return false;
2917 2917 }
2918 2918 };
2919 2919
2920 2920 void G1CollectedHeap::print() const { print_on(tty); }
2921 2921
2922 2922 void G1CollectedHeap::print_on(outputStream* st) const {
2923 2923 print_on(st, PrintHeapAtGCExtended);
2924 2924 }
2925 2925
2926 2926 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2927 2927 st->print(" %-20s", "garbage-first heap");
2928 2928 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2929 2929 capacity()/K, used_unlocked()/K);
2930 2930 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2931 2931 _g1_storage.low_boundary(),
2932 2932 _g1_storage.high(),
2933 2933 _g1_storage.high_boundary());
2934 2934 st->cr();
2935 2935 st->print(" region size " SIZE_FORMAT "K, ",
2936 2936 HeapRegion::GrainBytes/K);
2937 2937 size_t young_regions = _young_list->length();
2938 2938 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2939 2939 young_regions, young_regions * HeapRegion::GrainBytes / K);
2940 2940 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2941 2941 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2942 2942 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2943 2943 st->cr();
2944 2944 perm()->as_gen()->print_on(st);
2945 2945 if (extended) {
2946 2946 st->cr();
2947 2947 print_on_extended(st);
2948 2948 }
2949 2949 }
2950 2950
2951 2951 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2952 2952 PrintRegionClosure blk(st);
2953 2953 _hrs->iterate(&blk);
2954 2954 }
2955 2955
2956 2956 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2957 2957 if (G1CollectedHeap::use_parallel_gc_threads()) {
2958 2958 workers()->print_worker_threads_on(st);
2959 2959 }
2960 2960 _cmThread->print_on(st);
2961 2961 st->cr();
2962 2962 _cm->print_worker_threads_on(st);
2963 2963 _cg1r->print_worker_threads_on(st);
2964 2964 st->cr();
2965 2965 }
2966 2966
2967 2967 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2968 2968 if (G1CollectedHeap::use_parallel_gc_threads()) {
2969 2969 workers()->threads_do(tc);
2970 2970 }
2971 2971 tc->do_thread(_cmThread);
2972 2972 _cg1r->threads_do(tc);
2973 2973 }
2974 2974
2975 2975 void G1CollectedHeap::print_tracing_info() const {
2976 2976 // We'll overload this to mean "trace GC pause statistics."
2977 2977 if (TraceGen0Time || TraceGen1Time) {
2978 2978 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2979 2979 // to that.
2980 2980 g1_policy()->print_tracing_info();
2981 2981 }
2982 2982 if (G1SummarizeRSetStats) {
2983 2983 g1_rem_set()->print_summary_info();
2984 2984 }
2985 2985 if (G1SummarizeConcMark) {
2986 2986 concurrent_mark()->print_summary_info();
2987 2987 }
2988 2988 g1_policy()->print_yg_surv_rate_info();
2989 2989 SpecializationStats::print();
2990 2990 }
2991 2991
2992 2992 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2993 2993 HeapRegion* hr = heap_region_containing(addr);
2994 2994 if (hr == NULL) {
2995 2995 return 0;
2996 2996 } else {
2997 2997 return 1;
2998 2998 }
2999 2999 }
3000 3000
3001 3001 G1CollectedHeap* G1CollectedHeap::heap() {
3002 3002 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3003 3003 "not a garbage-first heap");
3004 3004 return _g1h;
3005 3005 }
3006 3006
3007 3007 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3008 3008 // always_do_update_barrier = false;
3009 3009 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3010 3010 // Call allocation profiler
3011 3011 AllocationProfiler::iterate_since_last_gc();
3012 3012 // Fill TLAB's and such
3013 3013 ensure_parsability(true);
3014 3014 }
3015 3015
3016 3016 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3017 3017 // FIXME: what is this about?
3018 3018 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3019 3019 // is set.
3020 3020 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3021 3021 "derived pointer present"));
3022 3022 // always_do_update_barrier = true;
3023 3023 }
3024 3024
3025 3025 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3026 3026 unsigned int gc_count_before,
3027 3027 bool* succeeded) {
3028 3028 assert_heap_not_locked_and_not_at_safepoint();
3029 3029 g1_policy()->record_stop_world_start();
3030 3030 VM_G1IncCollectionPause op(gc_count_before,
3031 3031 word_size,
3032 3032 false, /* should_initiate_conc_mark */
3033 3033 g1_policy()->max_pause_time_ms(),
3034 3034 GCCause::_g1_inc_collection_pause);
3035 3035 VMThread::execute(&op);
3036 3036
3037 3037 HeapWord* result = op.result();
3038 3038 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3039 3039 assert(result == NULL || ret_succeeded,
3040 3040 "the result should be NULL if the VM did not succeed");
3041 3041 *succeeded = ret_succeeded;
3042 3042
3043 3043 assert_heap_not_locked();
3044 3044 return result;
3045 3045 }
3046 3046
3047 3047 void
3048 3048 G1CollectedHeap::doConcurrentMark() {
3049 3049 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3050 3050 if (!_cmThread->in_progress()) {
3051 3051 _cmThread->set_started();
3052 3052 CGC_lock->notify();
3053 3053 }
3054 3054 }
3055 3055
3056 3056 class VerifyMarkedObjsClosure: public ObjectClosure {
3057 3057 G1CollectedHeap* _g1h;
3058 3058 public:
3059 3059 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
3060 3060 void do_object(oop obj) {
3061 3061 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
3062 3062 "markandsweep mark should agree with concurrent deadness");
3063 3063 }
3064 3064 };
3065 3065
3066 3066 void
3067 3067 G1CollectedHeap::checkConcurrentMark() {
3068 3068 VerifyMarkedObjsClosure verifycl(this);
3069 3069 // MutexLockerEx x(getMarkBitMapLock(),
3070 3070 // Mutex::_no_safepoint_check_flag);
3071 3071 object_iterate(&verifycl, false);
3072 3072 }
3073 3073
3074 3074 void G1CollectedHeap::do_sync_mark() {
3075 3075 _cm->checkpointRootsInitial();
3076 3076 _cm->markFromRoots();
3077 3077 _cm->checkpointRootsFinal(false);
3078 3078 }
3079 3079
3080 3080 // <NEW PREDICTION>
3081 3081
3082 3082 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3083 3083 bool young) {
3084 3084 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3085 3085 }
3086 3086
3087 3087 void G1CollectedHeap::check_if_region_is_too_expensive(double
3088 3088 predicted_time_ms) {
3089 3089 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3090 3090 }
3091 3091
3092 3092 size_t G1CollectedHeap::pending_card_num() {
3093 3093 size_t extra_cards = 0;
3094 3094 JavaThread *curr = Threads::first();
3095 3095 while (curr != NULL) {
3096 3096 DirtyCardQueue& dcq = curr->dirty_card_queue();
3097 3097 extra_cards += dcq.size();
3098 3098 curr = curr->next();
3099 3099 }
3100 3100 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3101 3101 size_t buffer_size = dcqs.buffer_size();
3102 3102 size_t buffer_num = dcqs.completed_buffers_num();
3103 3103 return buffer_size * buffer_num + extra_cards;
3104 3104 }
3105 3105
3106 3106 size_t G1CollectedHeap::max_pending_card_num() {
3107 3107 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3108 3108 size_t buffer_size = dcqs.buffer_size();
3109 3109 size_t buffer_num = dcqs.completed_buffers_num();
3110 3110 int thread_num = Threads::number_of_threads();
3111 3111 return (buffer_num + thread_num) * buffer_size;
3112 3112 }
3113 3113
3114 3114 size_t G1CollectedHeap::cards_scanned() {
3115 3115 return g1_rem_set()->cardsScanned();
3116 3116 }
3117 3117
3118 3118 void
3119 3119 G1CollectedHeap::setup_surviving_young_words() {
3120 3120 guarantee( _surviving_young_words == NULL, "pre-condition" );
3121 3121 size_t array_length = g1_policy()->young_cset_length();
3122 3122 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3123 3123 if (_surviving_young_words == NULL) {
3124 3124 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3125 3125 "Not enough space for young surv words summary.");
3126 3126 }
3127 3127 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3128 3128 #ifdef ASSERT
3129 3129 for (size_t i = 0; i < array_length; ++i) {
3130 3130 assert( _surviving_young_words[i] == 0, "memset above" );
3131 3131 }
3132 3132 #endif // !ASSERT
3133 3133 }
3134 3134
3135 3135 void
3136 3136 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3137 3137 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3138 3138 size_t array_length = g1_policy()->young_cset_length();
3139 3139 for (size_t i = 0; i < array_length; ++i)
3140 3140 _surviving_young_words[i] += surv_young_words[i];
3141 3141 }
3142 3142
3143 3143 void
3144 3144 G1CollectedHeap::cleanup_surviving_young_words() {
3145 3145 guarantee( _surviving_young_words != NULL, "pre-condition" );
3146 3146 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3147 3147 _surviving_young_words = NULL;
3148 3148 }
3149 3149
3150 3150 // </NEW PREDICTION>
3151 3151
3152 3152 struct PrepareForRSScanningClosure : public HeapRegionClosure {
3153 3153 bool doHeapRegion(HeapRegion *r) {
3154 3154 r->rem_set()->set_iter_claimed(0);
3155 3155 return false;
3156 3156 }
3157 3157 };
3158 3158
3159 3159 #if TASKQUEUE_STATS
3160 3160 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3161 3161 st->print_raw_cr("GC Task Stats");
3162 3162 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3163 3163 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3164 3164 }
3165 3165
3166 3166 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3167 3167 print_taskqueue_stats_hdr(st);
3168 3168
3169 3169 TaskQueueStats totals;
3170 3170 const int n = workers() != NULL ? workers()->total_workers() : 1;
3171 3171 for (int i = 0; i < n; ++i) {
3172 3172 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3173 3173 totals += task_queue(i)->stats;
3174 3174 }
3175 3175 st->print_raw("tot "); totals.print(st); st->cr();
3176 3176
3177 3177 DEBUG_ONLY(totals.verify());
3178 3178 }
3179 3179
3180 3180 void G1CollectedHeap::reset_taskqueue_stats() {
3181 3181 const int n = workers() != NULL ? workers()->total_workers() : 1;
3182 3182 for (int i = 0; i < n; ++i) {
3183 3183 task_queue(i)->stats.reset();
3184 3184 }
3185 3185 }
3186 3186 #endif // TASKQUEUE_STATS
3187 3187
3188 3188 bool
3189 3189 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3190 3190 assert_at_safepoint(true /* should_be_vm_thread */);
3191 3191 guarantee(!is_gc_active(), "collection is not reentrant");
3192 3192
3193 3193 if (GC_locker::check_active_before_gc()) {
3194 3194 return false;
3195 3195 }
3196 3196
3197 3197 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3198 3198 ResourceMark rm;
3199 3199
3200 3200 if (PrintHeapAtGC) {
3201 3201 Universe::print_heap_before_gc();
3202 3202 }
3203 3203
3204 3204 verify_region_sets_optional();
3205 3205 verify_dirty_young_regions();
3206 3206
3207 3207 {
3208 3208 // This call will decide whether this pause is an initial-mark
3209 3209 // pause. If it is, during_initial_mark_pause() will return true
3210 3210 // for the duration of this pause.
3211 3211 g1_policy()->decide_on_conc_mark_initiation();
3212 3212
3213 3213 char verbose_str[128];
3214 3214 sprintf(verbose_str, "GC pause ");
3215 3215 if (g1_policy()->in_young_gc_mode()) {
3216 3216 if (g1_policy()->full_young_gcs())
3217 3217 strcat(verbose_str, "(young)");
3218 3218 else
3219 3219 strcat(verbose_str, "(partial)");
3220 3220 }
3221 3221 if (g1_policy()->during_initial_mark_pause()) {
3222 3222 strcat(verbose_str, " (initial-mark)");
3223 3223 // We are about to start a marking cycle, so we increment the
3224 3224 // full collection counter.
3225 3225 increment_total_full_collections();
3226 3226 }
3227 3227
3228 3228 // if PrintGCDetails is on, we'll print long statistics information
3229 3229 // in the collector policy code, so let's not print this as the output
3230 3230 // is messy if we do.
3231 3231 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3232 3232 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3233 3233 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3234 3234
3235 3235 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3236 3236 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3237 3237
3238 3238 // If the secondary_free_list is not empty, append it to the
3239 3239 // free_list. No need to wait for the cleanup operation to finish;
3240 3240 // the region allocation code will check the secondary_free_list
3241 3241 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3242 3242 // set, skip this step so that the region allocation code has to
3243 3243 // get entries from the secondary_free_list.
3244 3244 if (!G1StressConcRegionFreeing) {
3245 3245 append_secondary_free_list_if_not_empty_with_lock();
3246 3246 }
3247 3247
3248 3248 increment_gc_time_stamp();
3249 3249
3250 3250 if (g1_policy()->in_young_gc_mode()) {
3251 3251 assert(check_young_list_well_formed(),
3252 3252 "young list should be well formed");
3253 3253 }
3254 3254
3255 3255 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3256 3256 IsGCActiveMark x;
3257 3257
3258 3258 gc_prologue(false);
3259 3259 increment_total_collections(false /* full gc */);
3260 3260
3261 3261 #if G1_REM_SET_LOGGING
3262 3262 gclog_or_tty->print_cr("\nJust chose CS, heap:");
3263 3263 print();
3264 3264 #endif
3265 3265
3266 3266 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3267 3267 HandleMark hm; // Discard invalid handles created during verification
3268 3268 gclog_or_tty->print(" VerifyBeforeGC:");
3269 3269 prepare_for_verify();
3270 3270 Universe::verify(false);
3271 3271 }
3272 3272
3273 3273 COMPILER2_PRESENT(DerivedPointerTable::clear());
3274 3274
3275 3275 // Please see comment in G1CollectedHeap::ref_processing_init()
3276 3276 // to see how reference processing currently works in G1.
3277 3277 //
3278 3278 // We want to turn off ref discovery, if necessary, and turn it back on
3279 3279 // on again later if we do. XXX Dubious: why is discovery disabled?
3280 3280 bool was_enabled = ref_processor()->discovery_enabled();
3281 3281 if (was_enabled) ref_processor()->disable_discovery();
3282 3282
3283 3283 // Forget the current alloc region (we might even choose it to be part
3284 3284 // of the collection set!).
3285 3285 release_mutator_alloc_region();
3286 3286
3287 3287 // The elapsed time induced by the start time below deliberately elides
3288 3288 // the possible verification above.
3289 3289 double start_time_sec = os::elapsedTime();
3290 3290 size_t start_used_bytes = used();
3291 3291
3292 3292 #if YOUNG_LIST_VERBOSE
3293 3293 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3294 3294 _young_list->print();
3295 3295 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3296 3296 #endif // YOUNG_LIST_VERBOSE
3297 3297
3298 3298 g1_policy()->record_collection_pause_start(start_time_sec,
3299 3299 start_used_bytes);
3300 3300
3301 3301 #if YOUNG_LIST_VERBOSE
3302 3302 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3303 3303 _young_list->print();
3304 3304 #endif // YOUNG_LIST_VERBOSE
3305 3305
3306 3306 if (g1_policy()->during_initial_mark_pause()) {
3307 3307 concurrent_mark()->checkpointRootsInitialPre();
3308 3308 }
3309 3309 save_marks();
3310 3310
3311 3311 // We must do this before any possible evacuation that should propagate
3312 3312 // marks.
3313 3313 if (mark_in_progress()) {
3314 3314 double start_time_sec = os::elapsedTime();
3315 3315
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3315 lines elided |
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3316 3316 _cm->drainAllSATBBuffers();
3317 3317 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3318 3318 g1_policy()->record_satb_drain_time(finish_mark_ms);
3319 3319 }
3320 3320 // Record the number of elements currently on the mark stack, so we
3321 3321 // only iterate over these. (Since evacuation may add to the mark
3322 3322 // stack, doing more exposes race conditions.) If no mark is in
3323 3323 // progress, this will be zero.
3324 3324 _cm->set_oops_do_bound();
3325 3325
3326 - if (mark_in_progress())
3326 + if (mark_in_progress()) {
3327 3327 concurrent_mark()->newCSet();
3328 + }
3328 3329
3329 3330 #if YOUNG_LIST_VERBOSE
3330 3331 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3331 3332 _young_list->print();
3332 3333 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3333 3334 #endif // YOUNG_LIST_VERBOSE
3334 3335
3335 3336 g1_policy()->choose_collection_set(target_pause_time_ms);
3336 3337
3338 + // We have chosen the complete collection set. If marking is
3339 + // active then, we clear the region fields of any of the
3340 + // concurrent marking tasks whose region fields point into
3341 + // the collection set as these values will become stale. This
3342 + // will cause the owning marking threads to claim a new region
3343 + // when marking restarts.
3344 + if (mark_in_progress()) {
3345 + concurrent_mark()->reset_active_task_region_fields_in_cset();
3346 + }
3347 +
3337 3348 // Nothing to do if we were unable to choose a collection set.
3338 3349 #if G1_REM_SET_LOGGING
3339 3350 gclog_or_tty->print_cr("\nAfter pause, heap:");
3340 3351 print();
3341 3352 #endif
3342 3353 PrepareForRSScanningClosure prepare_for_rs_scan;
3343 3354 collection_set_iterate(&prepare_for_rs_scan);
3344 3355
3345 3356 setup_surviving_young_words();
3346 3357
3347 3358 // Set up the gc allocation regions.
3348 3359 get_gc_alloc_regions();
3349 3360
3350 3361 // Actually do the work...
3351 3362 evacuate_collection_set();
3352 3363
3353 3364 free_collection_set(g1_policy()->collection_set());
3354 3365 g1_policy()->clear_collection_set();
3355 3366
3356 3367 cleanup_surviving_young_words();
3357 3368
3358 3369 // Start a new incremental collection set for the next pause.
3359 3370 g1_policy()->start_incremental_cset_building();
3360 3371
3361 3372 // Clear the _cset_fast_test bitmap in anticipation of adding
3362 3373 // regions to the incremental collection set for the next
3363 3374 // evacuation pause.
3364 3375 clear_cset_fast_test();
3365 3376
3366 3377 if (g1_policy()->in_young_gc_mode()) {
3367 3378 _young_list->reset_sampled_info();
3368 3379
3369 3380 // Don't check the whole heap at this point as the
3370 3381 // GC alloc regions from this pause have been tagged
3371 3382 // as survivors and moved on to the survivor list.
3372 3383 // Survivor regions will fail the !is_young() check.
3373 3384 assert(check_young_list_empty(false /* check_heap */),
3374 3385 "young list should be empty");
3375 3386
3376 3387 #if YOUNG_LIST_VERBOSE
3377 3388 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3378 3389 _young_list->print();
3379 3390 #endif // YOUNG_LIST_VERBOSE
3380 3391
3381 3392 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3382 3393 _young_list->first_survivor_region(),
3383 3394 _young_list->last_survivor_region());
3384 3395
3385 3396 _young_list->reset_auxilary_lists();
3386 3397 }
3387 3398
3388 3399 if (evacuation_failed()) {
3389 3400 _summary_bytes_used = recalculate_used();
3390 3401 } else {
3391 3402 // The "used" of the the collection set have already been subtracted
3392 3403 // when they were freed. Add in the bytes evacuated.
3393 3404 _summary_bytes_used += g1_policy()->bytes_in_to_space();
3394 3405 }
3395 3406
3396 3407 if (g1_policy()->in_young_gc_mode() &&
3397 3408 g1_policy()->during_initial_mark_pause()) {
3398 3409 concurrent_mark()->checkpointRootsInitialPost();
3399 3410 set_marking_started();
3400 3411 // CAUTION: after the doConcurrentMark() call below,
3401 3412 // the concurrent marking thread(s) could be running
3402 3413 // concurrently with us. Make sure that anything after
3403 3414 // this point does not assume that we are the only GC thread
3404 3415 // running. Note: of course, the actual marking work will
3405 3416 // not start until the safepoint itself is released in
3406 3417 // ConcurrentGCThread::safepoint_desynchronize().
3407 3418 doConcurrentMark();
3408 3419 }
3409 3420
3410 3421 allocate_dummy_regions();
3411 3422
3412 3423 #if YOUNG_LIST_VERBOSE
3413 3424 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3414 3425 _young_list->print();
3415 3426 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3416 3427 #endif // YOUNG_LIST_VERBOSE
3417 3428
3418 3429 init_mutator_alloc_region();
3419 3430
3420 3431 double end_time_sec = os::elapsedTime();
3421 3432 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3422 3433 g1_policy()->record_pause_time_ms(pause_time_ms);
3423 3434 g1_policy()->record_collection_pause_end();
3424 3435
3425 3436 MemoryService::track_memory_usage();
3426 3437
3427 3438 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3428 3439 HandleMark hm; // Discard invalid handles created during verification
3429 3440 gclog_or_tty->print(" VerifyAfterGC:");
3430 3441 prepare_for_verify();
3431 3442 Universe::verify(false);
3432 3443 }
3433 3444
3434 3445 if (was_enabled) ref_processor()->enable_discovery();
3435 3446
3436 3447 {
3437 3448 size_t expand_bytes = g1_policy()->expansion_amount();
3438 3449 if (expand_bytes > 0) {
3439 3450 size_t bytes_before = capacity();
3440 3451 if (!expand(expand_bytes)) {
3441 3452 // We failed to expand the heap so let's verify that
3442 3453 // committed/uncommitted amount match the backing store
3443 3454 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3444 3455 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3445 3456 }
3446 3457 }
3447 3458 }
3448 3459
3449 3460 if (mark_in_progress()) {
3450 3461 concurrent_mark()->update_g1_committed();
3451 3462 }
3452 3463
3453 3464 #ifdef TRACESPINNING
3454 3465 ParallelTaskTerminator::print_termination_counts();
3455 3466 #endif
3456 3467
3457 3468 gc_epilogue(false);
3458 3469 }
3459 3470
3460 3471 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3461 3472 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3462 3473 print_tracing_info();
3463 3474 vm_exit(-1);
3464 3475 }
3465 3476 }
3466 3477
3467 3478 verify_region_sets_optional();
3468 3479
3469 3480 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3470 3481 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3471 3482
3472 3483 if (PrintHeapAtGC) {
3473 3484 Universe::print_heap_after_gc();
3474 3485 }
3475 3486 g1mm()->update_counters();
3476 3487
3477 3488 if (G1SummarizeRSetStats &&
3478 3489 (G1SummarizeRSetStatsPeriod > 0) &&
3479 3490 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3480 3491 g1_rem_set()->print_summary_info();
3481 3492 }
3482 3493
3483 3494 return true;
3484 3495 }
3485 3496
3486 3497 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3487 3498 {
3488 3499 size_t gclab_word_size;
3489 3500 switch (purpose) {
3490 3501 case GCAllocForSurvived:
3491 3502 gclab_word_size = YoungPLABSize;
3492 3503 break;
3493 3504 case GCAllocForTenured:
3494 3505 gclab_word_size = OldPLABSize;
3495 3506 break;
3496 3507 default:
3497 3508 assert(false, "unknown GCAllocPurpose");
3498 3509 gclab_word_size = OldPLABSize;
3499 3510 break;
3500 3511 }
3501 3512 return gclab_word_size;
3502 3513 }
3503 3514
3504 3515 void G1CollectedHeap::init_mutator_alloc_region() {
3505 3516 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3506 3517 _mutator_alloc_region.init();
3507 3518 }
3508 3519
3509 3520 void G1CollectedHeap::release_mutator_alloc_region() {
3510 3521 _mutator_alloc_region.release();
3511 3522 assert(_mutator_alloc_region.get() == NULL, "post-condition");
3512 3523 }
3513 3524
3514 3525 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
3515 3526 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
3516 3527 // make sure we don't call set_gc_alloc_region() multiple times on
3517 3528 // the same region
3518 3529 assert(r == NULL || !r->is_gc_alloc_region(),
3519 3530 "shouldn't already be a GC alloc region");
3520 3531 assert(r == NULL || !r->isHumongous(),
3521 3532 "humongous regions shouldn't be used as GC alloc regions");
3522 3533
3523 3534 HeapWord* original_top = NULL;
3524 3535 if (r != NULL)
3525 3536 original_top = r->top();
3526 3537
3527 3538 // We will want to record the used space in r as being there before gc.
3528 3539 // One we install it as a GC alloc region it's eligible for allocation.
3529 3540 // So record it now and use it later.
3530 3541 size_t r_used = 0;
3531 3542 if (r != NULL) {
3532 3543 r_used = r->used();
3533 3544
3534 3545 if (G1CollectedHeap::use_parallel_gc_threads()) {
3535 3546 // need to take the lock to guard against two threads calling
3536 3547 // get_gc_alloc_region concurrently (very unlikely but...)
3537 3548 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3538 3549 r->save_marks();
3539 3550 }
3540 3551 }
3541 3552 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
3542 3553 _gc_alloc_regions[purpose] = r;
3543 3554 if (old_alloc_region != NULL) {
3544 3555 // Replace aliases too.
3545 3556 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3546 3557 if (_gc_alloc_regions[ap] == old_alloc_region) {
3547 3558 _gc_alloc_regions[ap] = r;
3548 3559 }
3549 3560 }
3550 3561 }
3551 3562 if (r != NULL) {
3552 3563 push_gc_alloc_region(r);
3553 3564 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
3554 3565 // We are using a region as a GC alloc region after it has been used
3555 3566 // as a mutator allocation region during the current marking cycle.
3556 3567 // The mutator-allocated objects are currently implicitly marked, but
3557 3568 // when we move hr->next_top_at_mark_start() forward at the the end
3558 3569 // of the GC pause, they won't be. We therefore mark all objects in
3559 3570 // the "gap". We do this object-by-object, since marking densely
3560 3571 // does not currently work right with marking bitmap iteration. This
3561 3572 // means we rely on TLAB filling at the start of pauses, and no
3562 3573 // "resuscitation" of filled TLAB's. If we want to do this, we need
3563 3574 // to fix the marking bitmap iteration.
3564 3575 HeapWord* curhw = r->next_top_at_mark_start();
3565 3576 HeapWord* t = original_top;
3566 3577
3567 3578 while (curhw < t) {
3568 3579 oop cur = (oop)curhw;
3569 3580 // We'll assume parallel for generality. This is rare code.
3570 3581 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
3571 3582 curhw = curhw + cur->size();
3572 3583 }
3573 3584 assert(curhw == t, "Should have parsed correctly.");
3574 3585 }
3575 3586 if (G1PolicyVerbose > 1) {
3576 3587 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
3577 3588 "for survivors:", r->bottom(), original_top, r->end());
3578 3589 r->print();
3579 3590 }
3580 3591 g1_policy()->record_before_bytes(r_used);
3581 3592 }
3582 3593 }
3583 3594
3584 3595 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
3585 3596 assert(Thread::current()->is_VM_thread() ||
3586 3597 FreeList_lock->owned_by_self(), "Precondition");
3587 3598 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3588 3599 "Precondition.");
3589 3600 hr->set_is_gc_alloc_region(true);
3590 3601 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3591 3602 _gc_alloc_region_list = hr;
3592 3603 }
3593 3604
3594 3605 #ifdef G1_DEBUG
3595 3606 class FindGCAllocRegion: public HeapRegionClosure {
3596 3607 public:
3597 3608 bool doHeapRegion(HeapRegion* r) {
3598 3609 if (r->is_gc_alloc_region()) {
3599 3610 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
3600 3611 r->hrs_index(), r->bottom());
3601 3612 }
3602 3613 return false;
3603 3614 }
3604 3615 };
3605 3616 #endif // G1_DEBUG
3606 3617
3607 3618 void G1CollectedHeap::forget_alloc_region_list() {
3608 3619 assert_at_safepoint(true /* should_be_vm_thread */);
3609 3620 while (_gc_alloc_region_list != NULL) {
3610 3621 HeapRegion* r = _gc_alloc_region_list;
3611 3622 assert(r->is_gc_alloc_region(), "Invariant.");
3612 3623 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3613 3624 // newly allocated data in order to be able to apply deferred updates
3614 3625 // before the GC is done for verification purposes (i.e to allow
3615 3626 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3616 3627 // collection.
3617 3628 r->ContiguousSpace::set_saved_mark();
3618 3629 _gc_alloc_region_list = r->next_gc_alloc_region();
3619 3630 r->set_next_gc_alloc_region(NULL);
3620 3631 r->set_is_gc_alloc_region(false);
3621 3632 if (r->is_survivor()) {
3622 3633 if (r->is_empty()) {
3623 3634 r->set_not_young();
3624 3635 } else {
3625 3636 _young_list->add_survivor_region(r);
3626 3637 }
3627 3638 }
3628 3639 }
3629 3640 #ifdef G1_DEBUG
3630 3641 FindGCAllocRegion fa;
3631 3642 heap_region_iterate(&fa);
3632 3643 #endif // G1_DEBUG
3633 3644 }
3634 3645
3635 3646
3636 3647 bool G1CollectedHeap::check_gc_alloc_regions() {
3637 3648 // TODO: allocation regions check
3638 3649 return true;
3639 3650 }
3640 3651
3641 3652 void G1CollectedHeap::get_gc_alloc_regions() {
3642 3653 // First, let's check that the GC alloc region list is empty (it should)
3643 3654 assert(_gc_alloc_region_list == NULL, "invariant");
3644 3655
3645 3656 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3646 3657 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3647 3658 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3648 3659
3649 3660 // Create new GC alloc regions.
3650 3661 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3651 3662 _retained_gc_alloc_regions[ap] = NULL;
3652 3663
3653 3664 if (alloc_region != NULL) {
3654 3665 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3655 3666
3656 3667 // let's make sure that the GC alloc region is not tagged as such
3657 3668 // outside a GC operation
3658 3669 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3659 3670
3660 3671 if (alloc_region->in_collection_set() ||
3661 3672 alloc_region->top() == alloc_region->end() ||
3662 3673 alloc_region->top() == alloc_region->bottom() ||
3663 3674 alloc_region->isHumongous()) {
3664 3675 // we will discard the current GC alloc region if
3665 3676 // * it's in the collection set (it can happen!),
3666 3677 // * it's already full (no point in using it),
3667 3678 // * it's empty (this means that it was emptied during
3668 3679 // a cleanup and it should be on the free list now), or
3669 3680 // * it's humongous (this means that it was emptied
3670 3681 // during a cleanup and was added to the free list, but
3671 3682 // has been subseqently used to allocate a humongous
3672 3683 // object that may be less than the region size).
3673 3684
3674 3685 alloc_region = NULL;
3675 3686 }
3676 3687 }
3677 3688
3678 3689 if (alloc_region == NULL) {
3679 3690 // we will get a new GC alloc region
3680 3691 alloc_region = new_gc_alloc_region(ap, HeapRegion::GrainWords);
3681 3692 } else {
3682 3693 // the region was retained from the last collection
3683 3694 ++_gc_alloc_region_counts[ap];
3684 3695 if (G1PrintHeapRegions) {
3685 3696 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
3686 3697 "top "PTR_FORMAT,
3687 3698 alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top());
3688 3699 }
3689 3700 }
3690 3701
3691 3702 if (alloc_region != NULL) {
3692 3703 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3693 3704 set_gc_alloc_region(ap, alloc_region);
3694 3705 }
3695 3706
3696 3707 assert(_gc_alloc_regions[ap] == NULL ||
3697 3708 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3698 3709 "the GC alloc region should be tagged as such");
3699 3710 assert(_gc_alloc_regions[ap] == NULL ||
3700 3711 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3701 3712 "the GC alloc region should be the same as the GC alloc list head");
3702 3713 }
3703 3714 // Set alternative regions for allocation purposes that have reached
3704 3715 // their limit.
3705 3716 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3706 3717 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3707 3718 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3708 3719 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3709 3720 }
3710 3721 }
3711 3722 assert(check_gc_alloc_regions(), "alloc regions messed up");
3712 3723 }
3713 3724
3714 3725 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3715 3726 // We keep a separate list of all regions that have been alloc regions in
3716 3727 // the current collection pause. Forget that now. This method will
3717 3728 // untag the GC alloc regions and tear down the GC alloc region
3718 3729 // list. It's desirable that no regions are tagged as GC alloc
3719 3730 // outside GCs.
3720 3731
3721 3732 forget_alloc_region_list();
3722 3733
3723 3734 // The current alloc regions contain objs that have survived
3724 3735 // collection. Make them no longer GC alloc regions.
3725 3736 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3726 3737 HeapRegion* r = _gc_alloc_regions[ap];
3727 3738 _retained_gc_alloc_regions[ap] = NULL;
3728 3739 _gc_alloc_region_counts[ap] = 0;
3729 3740
3730 3741 if (r != NULL) {
3731 3742 // we retain nothing on _gc_alloc_regions between GCs
3732 3743 set_gc_alloc_region(ap, NULL);
3733 3744
3734 3745 if (r->is_empty()) {
3735 3746 // We didn't actually allocate anything in it; let's just put
3736 3747 // it back on the free list.
3737 3748 _free_list.add_as_head(r);
3738 3749 } else if (_retain_gc_alloc_region[ap] && !totally) {
3739 3750 // retain it so that we can use it at the beginning of the next GC
3740 3751 _retained_gc_alloc_regions[ap] = r;
3741 3752 }
3742 3753 }
3743 3754 }
3744 3755 }
3745 3756
3746 3757 #ifndef PRODUCT
3747 3758 // Useful for debugging
3748 3759
3749 3760 void G1CollectedHeap::print_gc_alloc_regions() {
3750 3761 gclog_or_tty->print_cr("GC alloc regions");
3751 3762 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3752 3763 HeapRegion* r = _gc_alloc_regions[ap];
3753 3764 if (r == NULL) {
3754 3765 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3755 3766 } else {
3756 3767 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3757 3768 ap, r->bottom(), r->used());
3758 3769 }
3759 3770 }
3760 3771 }
3761 3772 #endif // PRODUCT
3762 3773
3763 3774 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3764 3775 _drain_in_progress = false;
3765 3776 set_evac_failure_closure(cl);
3766 3777 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3767 3778 }
3768 3779
3769 3780 void G1CollectedHeap::finalize_for_evac_failure() {
3770 3781 assert(_evac_failure_scan_stack != NULL &&
3771 3782 _evac_failure_scan_stack->length() == 0,
3772 3783 "Postcondition");
3773 3784 assert(!_drain_in_progress, "Postcondition");
3774 3785 delete _evac_failure_scan_stack;
3775 3786 _evac_failure_scan_stack = NULL;
3776 3787 }
3777 3788
3778 3789
3779 3790
3780 3791 // *** Sequential G1 Evacuation
3781 3792
3782 3793 class G1IsAliveClosure: public BoolObjectClosure {
3783 3794 G1CollectedHeap* _g1;
3784 3795 public:
3785 3796 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3786 3797 void do_object(oop p) { assert(false, "Do not call."); }
3787 3798 bool do_object_b(oop p) {
3788 3799 // It is reachable if it is outside the collection set, or is inside
3789 3800 // and forwarded.
3790 3801
3791 3802 #ifdef G1_DEBUG
3792 3803 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3793 3804 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3794 3805 !_g1->obj_in_cs(p) || p->is_forwarded());
3795 3806 #endif // G1_DEBUG
3796 3807
3797 3808 return !_g1->obj_in_cs(p) || p->is_forwarded();
3798 3809 }
3799 3810 };
3800 3811
3801 3812 class G1KeepAliveClosure: public OopClosure {
3802 3813 G1CollectedHeap* _g1;
3803 3814 public:
3804 3815 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3805 3816 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3806 3817 void do_oop( oop* p) {
3807 3818 oop obj = *p;
3808 3819 #ifdef G1_DEBUG
3809 3820 if (PrintGC && Verbose) {
3810 3821 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3811 3822 p, (void*) obj, (void*) *p);
3812 3823 }
3813 3824 #endif // G1_DEBUG
3814 3825
3815 3826 if (_g1->obj_in_cs(obj)) {
3816 3827 assert( obj->is_forwarded(), "invariant" );
3817 3828 *p = obj->forwardee();
3818 3829 #ifdef G1_DEBUG
3819 3830 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3820 3831 (void*) obj, (void*) *p);
3821 3832 #endif // G1_DEBUG
3822 3833 }
3823 3834 }
3824 3835 };
3825 3836
3826 3837 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3827 3838 private:
3828 3839 G1CollectedHeap* _g1;
3829 3840 DirtyCardQueue *_dcq;
3830 3841 CardTableModRefBS* _ct_bs;
3831 3842
3832 3843 public:
3833 3844 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3834 3845 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3835 3846
3836 3847 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3837 3848 virtual void do_oop( oop* p) { do_oop_work(p); }
3838 3849 template <class T> void do_oop_work(T* p) {
3839 3850 assert(_from->is_in_reserved(p), "paranoia");
3840 3851 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3841 3852 !_from->is_survivor()) {
3842 3853 size_t card_index = _ct_bs->index_for(p);
3843 3854 if (_ct_bs->mark_card_deferred(card_index)) {
3844 3855 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3845 3856 }
3846 3857 }
3847 3858 }
3848 3859 };
3849 3860
3850 3861 class RemoveSelfPointerClosure: public ObjectClosure {
3851 3862 private:
3852 3863 G1CollectedHeap* _g1;
3853 3864 ConcurrentMark* _cm;
3854 3865 HeapRegion* _hr;
3855 3866 size_t _prev_marked_bytes;
3856 3867 size_t _next_marked_bytes;
3857 3868 OopsInHeapRegionClosure *_cl;
3858 3869 public:
3859 3870 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
3860 3871 OopsInHeapRegionClosure* cl) :
3861 3872 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3862 3873 _next_marked_bytes(0), _cl(cl) {}
3863 3874
3864 3875 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3865 3876 size_t next_marked_bytes() { return _next_marked_bytes; }
3866 3877
3867 3878 // <original comment>
3868 3879 // The original idea here was to coalesce evacuated and dead objects.
3869 3880 // However that caused complications with the block offset table (BOT).
3870 3881 // In particular if there were two TLABs, one of them partially refined.
3871 3882 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3872 3883 // The BOT entries of the unrefined part of TLAB_2 point to the start
3873 3884 // of TLAB_2. If the last object of the TLAB_1 and the first object
3874 3885 // of TLAB_2 are coalesced, then the cards of the unrefined part
3875 3886 // would point into middle of the filler object.
3876 3887 // The current approach is to not coalesce and leave the BOT contents intact.
3877 3888 // </original comment>
3878 3889 //
3879 3890 // We now reset the BOT when we start the object iteration over the
3880 3891 // region and refine its entries for every object we come across. So
3881 3892 // the above comment is not really relevant and we should be able
3882 3893 // to coalesce dead objects if we want to.
3883 3894 void do_object(oop obj) {
3884 3895 HeapWord* obj_addr = (HeapWord*) obj;
3885 3896 assert(_hr->is_in(obj_addr), "sanity");
3886 3897 size_t obj_size = obj->size();
3887 3898 _hr->update_bot_for_object(obj_addr, obj_size);
3888 3899 if (obj->is_forwarded() && obj->forwardee() == obj) {
3889 3900 // The object failed to move.
3890 3901 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3891 3902 _cm->markPrev(obj);
3892 3903 assert(_cm->isPrevMarked(obj), "Should be marked!");
3893 3904 _prev_marked_bytes += (obj_size * HeapWordSize);
3894 3905 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3895 3906 _cm->markAndGrayObjectIfNecessary(obj);
3896 3907 }
3897 3908 obj->set_mark(markOopDesc::prototype());
3898 3909 // While we were processing RSet buffers during the
3899 3910 // collection, we actually didn't scan any cards on the
3900 3911 // collection set, since we didn't want to update remebered
3901 3912 // sets with entries that point into the collection set, given
3902 3913 // that live objects fromthe collection set are about to move
3903 3914 // and such entries will be stale very soon. This change also
3904 3915 // dealt with a reliability issue which involved scanning a
3905 3916 // card in the collection set and coming across an array that
3906 3917 // was being chunked and looking malformed. The problem is
3907 3918 // that, if evacuation fails, we might have remembered set
3908 3919 // entries missing given that we skipped cards on the
3909 3920 // collection set. So, we'll recreate such entries now.
3910 3921 obj->oop_iterate(_cl);
3911 3922 assert(_cm->isPrevMarked(obj), "Should be marked!");
3912 3923 } else {
3913 3924 // The object has been either evacuated or is dead. Fill it with a
3914 3925 // dummy object.
3915 3926 MemRegion mr((HeapWord*)obj, obj_size);
3916 3927 CollectedHeap::fill_with_object(mr);
3917 3928 _cm->clearRangeBothMaps(mr);
3918 3929 }
3919 3930 }
3920 3931 };
3921 3932
3922 3933 void G1CollectedHeap::remove_self_forwarding_pointers() {
3923 3934 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3924 3935 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3925 3936 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3926 3937 OopsInHeapRegionClosure *cl;
3927 3938 if (G1DeferredRSUpdate) {
3928 3939 cl = &deferred_update;
3929 3940 } else {
3930 3941 cl = &immediate_update;
3931 3942 }
3932 3943 HeapRegion* cur = g1_policy()->collection_set();
3933 3944 while (cur != NULL) {
3934 3945 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3935 3946 assert(!cur->isHumongous(), "sanity");
3936 3947
3937 3948 if (cur->evacuation_failed()) {
3938 3949 assert(cur->in_collection_set(), "bad CS");
3939 3950 RemoveSelfPointerClosure rspc(_g1h, cur, cl);
3940 3951
3941 3952 cur->reset_bot();
3942 3953 cl->set_region(cur);
3943 3954 cur->object_iterate(&rspc);
3944 3955
3945 3956 // A number of manipulations to make the TAMS be the current top,
3946 3957 // and the marked bytes be the ones observed in the iteration.
3947 3958 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3948 3959 // The comments below are the postconditions achieved by the
3949 3960 // calls. Note especially the last such condition, which says that
3950 3961 // the count of marked bytes has been properly restored.
3951 3962 cur->note_start_of_marking(false);
3952 3963 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3953 3964 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3954 3965 // _next_marked_bytes == prev_marked_bytes.
3955 3966 cur->note_end_of_marking();
3956 3967 // _prev_top_at_mark_start == top(),
3957 3968 // _prev_marked_bytes == prev_marked_bytes
3958 3969 }
3959 3970 // If there is no mark in progress, we modified the _next variables
3960 3971 // above needlessly, but harmlessly.
3961 3972 if (_g1h->mark_in_progress()) {
3962 3973 cur->note_start_of_marking(false);
3963 3974 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3964 3975 // _next_marked_bytes == next_marked_bytes.
3965 3976 }
3966 3977
3967 3978 // Now make sure the region has the right index in the sorted array.
3968 3979 g1_policy()->note_change_in_marked_bytes(cur);
3969 3980 }
3970 3981 cur = cur->next_in_collection_set();
3971 3982 }
3972 3983 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3973 3984
3974 3985 // Now restore saved marks, if any.
3975 3986 if (_objs_with_preserved_marks != NULL) {
3976 3987 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3977 3988 guarantee(_objs_with_preserved_marks->length() ==
3978 3989 _preserved_marks_of_objs->length(), "Both or none.");
3979 3990 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3980 3991 oop obj = _objs_with_preserved_marks->at(i);
3981 3992 markOop m = _preserved_marks_of_objs->at(i);
3982 3993 obj->set_mark(m);
3983 3994 }
3984 3995 // Delete the preserved marks growable arrays (allocated on the C heap).
3985 3996 delete _objs_with_preserved_marks;
3986 3997 delete _preserved_marks_of_objs;
3987 3998 _objs_with_preserved_marks = NULL;
3988 3999 _preserved_marks_of_objs = NULL;
3989 4000 }
3990 4001 }
3991 4002
3992 4003 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3993 4004 _evac_failure_scan_stack->push(obj);
3994 4005 }
3995 4006
3996 4007 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3997 4008 assert(_evac_failure_scan_stack != NULL, "precondition");
3998 4009
3999 4010 while (_evac_failure_scan_stack->length() > 0) {
4000 4011 oop obj = _evac_failure_scan_stack->pop();
4001 4012 _evac_failure_closure->set_region(heap_region_containing(obj));
4002 4013 obj->oop_iterate_backwards(_evac_failure_closure);
4003 4014 }
4004 4015 }
4005 4016
4006 4017 oop
4007 4018 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4008 4019 oop old) {
4009 4020 assert(obj_in_cs(old),
4010 4021 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4011 4022 (HeapWord*) old));
4012 4023 markOop m = old->mark();
4013 4024 oop forward_ptr = old->forward_to_atomic(old);
4014 4025 if (forward_ptr == NULL) {
4015 4026 // Forward-to-self succeeded.
4016 4027 if (_evac_failure_closure != cl) {
4017 4028 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4018 4029 assert(!_drain_in_progress,
4019 4030 "Should only be true while someone holds the lock.");
4020 4031 // Set the global evac-failure closure to the current thread's.
4021 4032 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4022 4033 set_evac_failure_closure(cl);
4023 4034 // Now do the common part.
4024 4035 handle_evacuation_failure_common(old, m);
4025 4036 // Reset to NULL.
4026 4037 set_evac_failure_closure(NULL);
4027 4038 } else {
4028 4039 // The lock is already held, and this is recursive.
4029 4040 assert(_drain_in_progress, "This should only be the recursive case.");
4030 4041 handle_evacuation_failure_common(old, m);
4031 4042 }
4032 4043 return old;
4033 4044 } else {
4034 4045 // Forward-to-self failed. Either someone else managed to allocate
4035 4046 // space for this object (old != forward_ptr) or they beat us in
4036 4047 // self-forwarding it (old == forward_ptr).
4037 4048 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4038 4049 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4039 4050 "should not be in the CSet",
4040 4051 (HeapWord*) old, (HeapWord*) forward_ptr));
4041 4052 return forward_ptr;
4042 4053 }
4043 4054 }
4044 4055
4045 4056 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4046 4057 set_evacuation_failed(true);
4047 4058
4048 4059 preserve_mark_if_necessary(old, m);
4049 4060
4050 4061 HeapRegion* r = heap_region_containing(old);
4051 4062 if (!r->evacuation_failed()) {
4052 4063 r->set_evacuation_failed(true);
4053 4064 if (G1PrintHeapRegions) {
4054 4065 gclog_or_tty->print("overflow in heap region "PTR_FORMAT" "
4055 4066 "["PTR_FORMAT","PTR_FORMAT")\n",
4056 4067 r, r->bottom(), r->end());
4057 4068 }
4058 4069 }
4059 4070
4060 4071 push_on_evac_failure_scan_stack(old);
4061 4072
4062 4073 if (!_drain_in_progress) {
4063 4074 // prevent recursion in copy_to_survivor_space()
4064 4075 _drain_in_progress = true;
4065 4076 drain_evac_failure_scan_stack();
4066 4077 _drain_in_progress = false;
4067 4078 }
4068 4079 }
4069 4080
4070 4081 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4071 4082 assert(evacuation_failed(), "Oversaving!");
4072 4083 // We want to call the "for_promotion_failure" version only in the
4073 4084 // case of a promotion failure.
4074 4085 if (m->must_be_preserved_for_promotion_failure(obj)) {
4075 4086 if (_objs_with_preserved_marks == NULL) {
4076 4087 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4077 4088 _objs_with_preserved_marks =
4078 4089 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4079 4090 _preserved_marks_of_objs =
4080 4091 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4081 4092 }
4082 4093 _objs_with_preserved_marks->push(obj);
4083 4094 _preserved_marks_of_objs->push(m);
4084 4095 }
4085 4096 }
4086 4097
4087 4098 // *** Parallel G1 Evacuation
4088 4099
4089 4100 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4090 4101 size_t word_size) {
4091 4102 assert(!isHumongous(word_size),
4092 4103 err_msg("we should not be seeing humongous allocation requests "
4093 4104 "during GC, word_size = "SIZE_FORMAT, word_size));
4094 4105
4095 4106 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
4096 4107 // let the caller handle alloc failure
4097 4108 if (alloc_region == NULL) return NULL;
4098 4109
4099 4110 HeapWord* block = alloc_region->par_allocate(word_size);
4100 4111 if (block == NULL) {
4101 4112 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
4102 4113 }
4103 4114 return block;
4104 4115 }
4105 4116
4106 4117 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
4107 4118 bool par) {
4108 4119 // Another thread might have obtained alloc_region for the given
4109 4120 // purpose, and might be attempting to allocate in it, and might
4110 4121 // succeed. Therefore, we can't do the "finalization" stuff on the
4111 4122 // region below until we're sure the last allocation has happened.
4112 4123 // We ensure this by allocating the remaining space with a garbage
4113 4124 // object.
4114 4125 if (par) par_allocate_remaining_space(alloc_region);
4115 4126 // Now we can do the post-GC stuff on the region.
4116 4127 alloc_region->note_end_of_copying();
4117 4128 g1_policy()->record_after_bytes(alloc_region->used());
4118 4129 }
4119 4130
4120 4131 HeapWord*
4121 4132 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
4122 4133 HeapRegion* alloc_region,
4123 4134 bool par,
4124 4135 size_t word_size) {
4125 4136 assert(!isHumongous(word_size),
4126 4137 err_msg("we should not be seeing humongous allocation requests "
4127 4138 "during GC, word_size = "SIZE_FORMAT, word_size));
4128 4139
4129 4140 // We need to make sure we serialize calls to this method. Given
4130 4141 // that the FreeList_lock guards accesses to the free_list anyway,
4131 4142 // and we need to potentially remove a region from it, we'll use it
4132 4143 // to protect the whole call.
4133 4144 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4134 4145
4135 4146 HeapWord* block = NULL;
4136 4147 // In the parallel case, a previous thread to obtain the lock may have
4137 4148 // already assigned a new gc_alloc_region.
4138 4149 if (alloc_region != _gc_alloc_regions[purpose]) {
4139 4150 assert(par, "But should only happen in parallel case.");
4140 4151 alloc_region = _gc_alloc_regions[purpose];
4141 4152 if (alloc_region == NULL) return NULL;
4142 4153 block = alloc_region->par_allocate(word_size);
4143 4154 if (block != NULL) return block;
4144 4155 // Otherwise, continue; this new region is empty, too.
4145 4156 }
4146 4157 assert(alloc_region != NULL, "We better have an allocation region");
4147 4158 retire_alloc_region(alloc_region, par);
4148 4159
4149 4160 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
4150 4161 // Cannot allocate more regions for the given purpose.
4151 4162 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
4152 4163 // Is there an alternative?
4153 4164 if (purpose != alt_purpose) {
4154 4165 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
4155 4166 // Has not the alternative region been aliased?
4156 4167 if (alloc_region != alt_region && alt_region != NULL) {
4157 4168 // Try to allocate in the alternative region.
4158 4169 if (par) {
4159 4170 block = alt_region->par_allocate(word_size);
4160 4171 } else {
4161 4172 block = alt_region->allocate(word_size);
4162 4173 }
4163 4174 // Make an alias.
4164 4175 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
4165 4176 if (block != NULL) {
4166 4177 return block;
4167 4178 }
4168 4179 retire_alloc_region(alt_region, par);
4169 4180 }
4170 4181 // Both the allocation region and the alternative one are full
4171 4182 // and aliased, replace them with a new allocation region.
4172 4183 purpose = alt_purpose;
4173 4184 } else {
4174 4185 set_gc_alloc_region(purpose, NULL);
4175 4186 return NULL;
4176 4187 }
4177 4188 }
4178 4189
4179 4190 // Now allocate a new region for allocation.
4180 4191 alloc_region = new_gc_alloc_region(purpose, word_size);
4181 4192
4182 4193 // let the caller handle alloc failure
4183 4194 if (alloc_region != NULL) {
4184 4195
4185 4196 assert(check_gc_alloc_regions(), "alloc regions messed up");
4186 4197 assert(alloc_region->saved_mark_at_top(),
4187 4198 "Mark should have been saved already.");
4188 4199 // This must be done last: once it's installed, other regions may
4189 4200 // allocate in it (without holding the lock.)
4190 4201 set_gc_alloc_region(purpose, alloc_region);
4191 4202
4192 4203 if (par) {
4193 4204 block = alloc_region->par_allocate(word_size);
4194 4205 } else {
4195 4206 block = alloc_region->allocate(word_size);
4196 4207 }
4197 4208 // Caller handles alloc failure.
4198 4209 } else {
4199 4210 // This sets other apis using the same old alloc region to NULL, also.
4200 4211 set_gc_alloc_region(purpose, NULL);
4201 4212 }
4202 4213 return block; // May be NULL.
4203 4214 }
4204 4215
4205 4216 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
4206 4217 HeapWord* block = NULL;
4207 4218 size_t free_words;
4208 4219 do {
4209 4220 free_words = r->free()/HeapWordSize;
4210 4221 // If there's too little space, no one can allocate, so we're done.
4211 4222 if (free_words < CollectedHeap::min_fill_size()) return;
4212 4223 // Otherwise, try to claim it.
4213 4224 block = r->par_allocate(free_words);
4214 4225 } while (block == NULL);
4215 4226 fill_with_object(block, free_words);
4216 4227 }
4217 4228
4218 4229 #ifndef PRODUCT
4219 4230 bool GCLabBitMapClosure::do_bit(size_t offset) {
4220 4231 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4221 4232 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4222 4233 return true;
4223 4234 }
4224 4235 #endif // PRODUCT
4225 4236
4226 4237 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4227 4238 : _g1h(g1h),
4228 4239 _refs(g1h->task_queue(queue_num)),
4229 4240 _dcq(&g1h->dirty_card_queue_set()),
4230 4241 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4231 4242 _g1_rem(g1h->g1_rem_set()),
4232 4243 _hash_seed(17), _queue_num(queue_num),
4233 4244 _term_attempts(0),
4234 4245 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4235 4246 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4236 4247 _age_table(false),
4237 4248 _strong_roots_time(0), _term_time(0),
4238 4249 _alloc_buffer_waste(0), _undo_waste(0)
4239 4250 {
4240 4251 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4241 4252 // we "sacrifice" entry 0 to keep track of surviving bytes for
4242 4253 // non-young regions (where the age is -1)
4243 4254 // We also add a few elements at the beginning and at the end in
4244 4255 // an attempt to eliminate cache contention
4245 4256 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4246 4257 size_t array_length = PADDING_ELEM_NUM +
4247 4258 real_length +
4248 4259 PADDING_ELEM_NUM;
4249 4260 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4250 4261 if (_surviving_young_words_base == NULL)
4251 4262 vm_exit_out_of_memory(array_length * sizeof(size_t),
4252 4263 "Not enough space for young surv histo.");
4253 4264 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4254 4265 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4255 4266
4256 4267 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4257 4268 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4258 4269
4259 4270 _start = os::elapsedTime();
4260 4271 }
4261 4272
4262 4273 void
4263 4274 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4264 4275 {
4265 4276 st->print_raw_cr("GC Termination Stats");
4266 4277 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4267 4278 " ------waste (KiB)------");
4268 4279 st->print_raw_cr("thr ms ms % ms % attempts"
4269 4280 " total alloc undo");
4270 4281 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4271 4282 " ------- ------- -------");
4272 4283 }
4273 4284
4274 4285 void
4275 4286 G1ParScanThreadState::print_termination_stats(int i,
4276 4287 outputStream* const st) const
4277 4288 {
4278 4289 const double elapsed_ms = elapsed_time() * 1000.0;
4279 4290 const double s_roots_ms = strong_roots_time() * 1000.0;
4280 4291 const double term_ms = term_time() * 1000.0;
4281 4292 st->print_cr("%3d %9.2f %9.2f %6.2f "
4282 4293 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4283 4294 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4284 4295 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4285 4296 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4286 4297 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4287 4298 alloc_buffer_waste() * HeapWordSize / K,
4288 4299 undo_waste() * HeapWordSize / K);
4289 4300 }
4290 4301
4291 4302 #ifdef ASSERT
4292 4303 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4293 4304 assert(ref != NULL, "invariant");
4294 4305 assert(UseCompressedOops, "sanity");
4295 4306 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4296 4307 oop p = oopDesc::load_decode_heap_oop(ref);
4297 4308 assert(_g1h->is_in_g1_reserved(p),
4298 4309 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4299 4310 return true;
4300 4311 }
4301 4312
4302 4313 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4303 4314 assert(ref != NULL, "invariant");
4304 4315 if (has_partial_array_mask(ref)) {
4305 4316 // Must be in the collection set--it's already been copied.
4306 4317 oop p = clear_partial_array_mask(ref);
4307 4318 assert(_g1h->obj_in_cs(p),
4308 4319 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4309 4320 } else {
4310 4321 oop p = oopDesc::load_decode_heap_oop(ref);
4311 4322 assert(_g1h->is_in_g1_reserved(p),
4312 4323 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4313 4324 }
4314 4325 return true;
4315 4326 }
4316 4327
4317 4328 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4318 4329 if (ref.is_narrow()) {
4319 4330 return verify_ref((narrowOop*) ref);
4320 4331 } else {
4321 4332 return verify_ref((oop*) ref);
4322 4333 }
4323 4334 }
4324 4335 #endif // ASSERT
4325 4336
4326 4337 void G1ParScanThreadState::trim_queue() {
4327 4338 StarTask ref;
4328 4339 do {
4329 4340 // Drain the overflow stack first, so other threads can steal.
4330 4341 while (refs()->pop_overflow(ref)) {
4331 4342 deal_with_reference(ref);
4332 4343 }
4333 4344 while (refs()->pop_local(ref)) {
4334 4345 deal_with_reference(ref);
4335 4346 }
4336 4347 } while (!refs()->is_empty());
4337 4348 }
4338 4349
4339 4350 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4340 4351 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4341 4352 _par_scan_state(par_scan_state) { }
4342 4353
4343 4354 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
4344 4355 // This is called _after_ do_oop_work has been called, hence after
4345 4356 // the object has been relocated to its new location and *p points
4346 4357 // to its new location.
4347 4358
4348 4359 T heap_oop = oopDesc::load_heap_oop(p);
4349 4360 if (!oopDesc::is_null(heap_oop)) {
4350 4361 oop obj = oopDesc::decode_heap_oop(heap_oop);
4351 4362 HeapWord* addr = (HeapWord*)obj;
4352 4363 if (_g1->is_in_g1_reserved(addr)) {
4353 4364 _cm->grayRoot(oop(addr));
4354 4365 }
4355 4366 }
4356 4367 }
4357 4368
4358 4369 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4359 4370 size_t word_sz = old->size();
4360 4371 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4361 4372 // +1 to make the -1 indexes valid...
4362 4373 int young_index = from_region->young_index_in_cset()+1;
4363 4374 assert( (from_region->is_young() && young_index > 0) ||
4364 4375 (!from_region->is_young() && young_index == 0), "invariant" );
4365 4376 G1CollectorPolicy* g1p = _g1->g1_policy();
4366 4377 markOop m = old->mark();
4367 4378 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4368 4379 : m->age();
4369 4380 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4370 4381 word_sz);
4371 4382 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4372 4383 oop obj = oop(obj_ptr);
4373 4384
4374 4385 if (obj_ptr == NULL) {
4375 4386 // This will either forward-to-self, or detect that someone else has
4376 4387 // installed a forwarding pointer.
4377 4388 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4378 4389 return _g1->handle_evacuation_failure_par(cl, old);
4379 4390 }
4380 4391
4381 4392 // We're going to allocate linearly, so might as well prefetch ahead.
4382 4393 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4383 4394
4384 4395 oop forward_ptr = old->forward_to_atomic(obj);
4385 4396 if (forward_ptr == NULL) {
4386 4397 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4387 4398 if (g1p->track_object_age(alloc_purpose)) {
4388 4399 // We could simply do obj->incr_age(). However, this causes a
4389 4400 // performance issue. obj->incr_age() will first check whether
4390 4401 // the object has a displaced mark by checking its mark word;
4391 4402 // getting the mark word from the new location of the object
4392 4403 // stalls. So, given that we already have the mark word and we
4393 4404 // are about to install it anyway, it's better to increase the
4394 4405 // age on the mark word, when the object does not have a
4395 4406 // displaced mark word. We're not expecting many objects to have
4396 4407 // a displaced marked word, so that case is not optimized
4397 4408 // further (it could be...) and we simply call obj->incr_age().
4398 4409
4399 4410 if (m->has_displaced_mark_helper()) {
4400 4411 // in this case, we have to install the mark word first,
4401 4412 // otherwise obj looks to be forwarded (the old mark word,
4402 4413 // which contains the forward pointer, was copied)
4403 4414 obj->set_mark(m);
4404 4415 obj->incr_age();
4405 4416 } else {
4406 4417 m = m->incr_age();
4407 4418 obj->set_mark(m);
4408 4419 }
4409 4420 _par_scan_state->age_table()->add(obj, word_sz);
4410 4421 } else {
4411 4422 obj->set_mark(m);
4412 4423 }
4413 4424
4414 4425 // preserve "next" mark bit
4415 4426 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4416 4427 if (!use_local_bitmaps ||
4417 4428 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4418 4429 // if we couldn't mark it on the local bitmap (this happens when
4419 4430 // the object was not allocated in the GCLab), we have to bite
4420 4431 // the bullet and do the standard parallel mark
4421 4432 _cm->markAndGrayObjectIfNecessary(obj);
4422 4433 }
4423 4434 #if 1
4424 4435 if (_g1->isMarkedNext(old)) {
4425 4436 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4426 4437 }
4427 4438 #endif
4428 4439 }
4429 4440
4430 4441 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4431 4442 surv_young_words[young_index] += word_sz;
4432 4443
4433 4444 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4434 4445 arrayOop(old)->set_length(0);
4435 4446 oop* old_p = set_partial_array_mask(old);
4436 4447 _par_scan_state->push_on_queue(old_p);
4437 4448 } else {
4438 4449 // No point in using the slower heap_region_containing() method,
4439 4450 // given that we know obj is in the heap.
4440 4451 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4441 4452 obj->oop_iterate_backwards(_scanner);
4442 4453 }
4443 4454 } else {
4444 4455 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4445 4456 obj = forward_ptr;
4446 4457 }
4447 4458 return obj;
4448 4459 }
4449 4460
4450 4461 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4451 4462 template <class T>
4452 4463 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
4453 4464 ::do_oop_work(T* p) {
4454 4465 oop obj = oopDesc::load_decode_heap_oop(p);
4455 4466 assert(barrier != G1BarrierRS || obj != NULL,
4456 4467 "Precondition: G1BarrierRS implies obj is nonNull");
4457 4468
4458 4469 // here the null check is implicit in the cset_fast_test() test
4459 4470 if (_g1->in_cset_fast_test(obj)) {
4460 4471 #if G1_REM_SET_LOGGING
4461 4472 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4462 4473 "into CS.", p, (void*) obj);
4463 4474 #endif
4464 4475 if (obj->is_forwarded()) {
4465 4476 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4466 4477 } else {
4467 4478 oop copy_oop = copy_to_survivor_space(obj);
4468 4479 oopDesc::encode_store_heap_oop(p, copy_oop);
4469 4480 }
4470 4481 // When scanning the RS, we only care about objs in CS.
4471 4482 if (barrier == G1BarrierRS) {
4472 4483 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4473 4484 }
4474 4485 }
4475 4486
4476 4487 if (barrier == G1BarrierEvac && obj != NULL) {
4477 4488 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4478 4489 }
4479 4490
4480 4491 if (do_gen_barrier && obj != NULL) {
4481 4492 par_do_barrier(p);
4482 4493 }
4483 4494 }
4484 4495
4485 4496 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4486 4497 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4487 4498
4488 4499 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4489 4500 assert(has_partial_array_mask(p), "invariant");
4490 4501 oop old = clear_partial_array_mask(p);
4491 4502 assert(old->is_objArray(), "must be obj array");
4492 4503 assert(old->is_forwarded(), "must be forwarded");
4493 4504 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4494 4505
4495 4506 objArrayOop obj = objArrayOop(old->forwardee());
4496 4507 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4497 4508 // Process ParGCArrayScanChunk elements now
4498 4509 // and push the remainder back onto queue
4499 4510 int start = arrayOop(old)->length();
4500 4511 int end = obj->length();
4501 4512 int remainder = end - start;
4502 4513 assert(start <= end, "just checking");
4503 4514 if (remainder > 2 * ParGCArrayScanChunk) {
4504 4515 // Test above combines last partial chunk with a full chunk
4505 4516 end = start + ParGCArrayScanChunk;
4506 4517 arrayOop(old)->set_length(end);
4507 4518 // Push remainder.
4508 4519 oop* old_p = set_partial_array_mask(old);
4509 4520 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4510 4521 _par_scan_state->push_on_queue(old_p);
4511 4522 } else {
4512 4523 // Restore length so that the heap remains parsable in
4513 4524 // case of evacuation failure.
4514 4525 arrayOop(old)->set_length(end);
4515 4526 }
4516 4527 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4517 4528 // process our set of indices (include header in first chunk)
4518 4529 obj->oop_iterate_range(&_scanner, start, end);
4519 4530 }
4520 4531
4521 4532 class G1ParEvacuateFollowersClosure : public VoidClosure {
4522 4533 protected:
4523 4534 G1CollectedHeap* _g1h;
4524 4535 G1ParScanThreadState* _par_scan_state;
4525 4536 RefToScanQueueSet* _queues;
4526 4537 ParallelTaskTerminator* _terminator;
4527 4538
4528 4539 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4529 4540 RefToScanQueueSet* queues() { return _queues; }
4530 4541 ParallelTaskTerminator* terminator() { return _terminator; }
4531 4542
4532 4543 public:
4533 4544 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4534 4545 G1ParScanThreadState* par_scan_state,
4535 4546 RefToScanQueueSet* queues,
4536 4547 ParallelTaskTerminator* terminator)
4537 4548 : _g1h(g1h), _par_scan_state(par_scan_state),
4538 4549 _queues(queues), _terminator(terminator) {}
4539 4550
4540 4551 void do_void();
4541 4552
4542 4553 private:
4543 4554 inline bool offer_termination();
4544 4555 };
4545 4556
4546 4557 bool G1ParEvacuateFollowersClosure::offer_termination() {
4547 4558 G1ParScanThreadState* const pss = par_scan_state();
4548 4559 pss->start_term_time();
4549 4560 const bool res = terminator()->offer_termination();
4550 4561 pss->end_term_time();
4551 4562 return res;
4552 4563 }
4553 4564
4554 4565 void G1ParEvacuateFollowersClosure::do_void() {
4555 4566 StarTask stolen_task;
4556 4567 G1ParScanThreadState* const pss = par_scan_state();
4557 4568 pss->trim_queue();
4558 4569
4559 4570 do {
4560 4571 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4561 4572 assert(pss->verify_task(stolen_task), "sanity");
4562 4573 if (stolen_task.is_narrow()) {
4563 4574 pss->deal_with_reference((narrowOop*) stolen_task);
4564 4575 } else {
4565 4576 pss->deal_with_reference((oop*) stolen_task);
4566 4577 }
4567 4578
4568 4579 // We've just processed a reference and we might have made
4569 4580 // available new entries on the queues. So we have to make sure
4570 4581 // we drain the queues as necessary.
4571 4582 pss->trim_queue();
4572 4583 }
4573 4584 } while (!offer_termination());
4574 4585
4575 4586 pss->retire_alloc_buffers();
4576 4587 }
4577 4588
4578 4589 class G1ParTask : public AbstractGangTask {
4579 4590 protected:
4580 4591 G1CollectedHeap* _g1h;
4581 4592 RefToScanQueueSet *_queues;
4582 4593 ParallelTaskTerminator _terminator;
4583 4594 int _n_workers;
4584 4595
4585 4596 Mutex _stats_lock;
4586 4597 Mutex* stats_lock() { return &_stats_lock; }
4587 4598
4588 4599 size_t getNCards() {
4589 4600 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4590 4601 / G1BlockOffsetSharedArray::N_bytes;
4591 4602 }
4592 4603
4593 4604 public:
4594 4605 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4595 4606 : AbstractGangTask("G1 collection"),
4596 4607 _g1h(g1h),
4597 4608 _queues(task_queues),
4598 4609 _terminator(workers, _queues),
4599 4610 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4600 4611 _n_workers(workers)
4601 4612 {}
4602 4613
4603 4614 RefToScanQueueSet* queues() { return _queues; }
4604 4615
4605 4616 RefToScanQueue *work_queue(int i) {
4606 4617 return queues()->queue(i);
4607 4618 }
4608 4619
4609 4620 void work(int i) {
4610 4621 if (i >= _n_workers) return; // no work needed this round
4611 4622
4612 4623 double start_time_ms = os::elapsedTime() * 1000.0;
4613 4624 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4614 4625
4615 4626 ResourceMark rm;
4616 4627 HandleMark hm;
4617 4628
4618 4629 G1ParScanThreadState pss(_g1h, i);
4619 4630 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4620 4631 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4621 4632 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4622 4633
4623 4634 pss.set_evac_closure(&scan_evac_cl);
4624 4635 pss.set_evac_failure_closure(&evac_failure_cl);
4625 4636 pss.set_partial_scan_closure(&partial_scan_cl);
4626 4637
4627 4638 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4628 4639 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4629 4640 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4630 4641 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4631 4642
4632 4643 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4633 4644 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4634 4645 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4635 4646
4636 4647 OopsInHeapRegionClosure *scan_root_cl;
4637 4648 OopsInHeapRegionClosure *scan_perm_cl;
4638 4649
4639 4650 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4640 4651 scan_root_cl = &scan_mark_root_cl;
4641 4652 scan_perm_cl = &scan_mark_perm_cl;
4642 4653 } else {
4643 4654 scan_root_cl = &only_scan_root_cl;
4644 4655 scan_perm_cl = &only_scan_perm_cl;
4645 4656 }
4646 4657
4647 4658 pss.start_strong_roots();
4648 4659 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4649 4660 SharedHeap::SO_AllClasses,
4650 4661 scan_root_cl,
4651 4662 &push_heap_rs_cl,
4652 4663 scan_perm_cl,
4653 4664 i);
4654 4665 pss.end_strong_roots();
4655 4666 {
4656 4667 double start = os::elapsedTime();
4657 4668 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4658 4669 evac.do_void();
4659 4670 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4660 4671 double term_ms = pss.term_time()*1000.0;
4661 4672 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4662 4673 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4663 4674 }
4664 4675 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4665 4676 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4666 4677
4667 4678 // Clean up any par-expanded rem sets.
4668 4679 HeapRegionRemSet::par_cleanup();
4669 4680
4670 4681 if (ParallelGCVerbose) {
4671 4682 MutexLocker x(stats_lock());
4672 4683 pss.print_termination_stats(i);
4673 4684 }
4674 4685
4675 4686 assert(pss.refs()->is_empty(), "should be empty");
4676 4687 double end_time_ms = os::elapsedTime() * 1000.0;
4677 4688 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4678 4689 }
4679 4690 };
4680 4691
4681 4692 // *** Common G1 Evacuation Stuff
4682 4693
4683 4694 // This method is run in a GC worker.
4684 4695
4685 4696 void
4686 4697 G1CollectedHeap::
4687 4698 g1_process_strong_roots(bool collecting_perm_gen,
4688 4699 SharedHeap::ScanningOption so,
4689 4700 OopClosure* scan_non_heap_roots,
4690 4701 OopsInHeapRegionClosure* scan_rs,
4691 4702 OopsInGenClosure* scan_perm,
4692 4703 int worker_i) {
4693 4704 // First scan the strong roots, including the perm gen.
4694 4705 double ext_roots_start = os::elapsedTime();
4695 4706 double closure_app_time_sec = 0.0;
4696 4707
4697 4708 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4698 4709 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4699 4710 buf_scan_perm.set_generation(perm_gen());
4700 4711
4701 4712 // Walk the code cache w/o buffering, because StarTask cannot handle
4702 4713 // unaligned oop locations.
4703 4714 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4704 4715
4705 4716 process_strong_roots(false, // no scoping; this is parallel code
4706 4717 collecting_perm_gen, so,
4707 4718 &buf_scan_non_heap_roots,
4708 4719 &eager_scan_code_roots,
4709 4720 &buf_scan_perm);
4710 4721
4711 4722 // Finish up any enqueued closure apps.
4712 4723 buf_scan_non_heap_roots.done();
4713 4724 buf_scan_perm.done();
4714 4725 double ext_roots_end = os::elapsedTime();
4715 4726 g1_policy()->reset_obj_copy_time(worker_i);
4716 4727 double obj_copy_time_sec =
4717 4728 buf_scan_non_heap_roots.closure_app_seconds() +
4718 4729 buf_scan_perm.closure_app_seconds();
4719 4730 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4720 4731 double ext_root_time_ms =
4721 4732 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4722 4733 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4723 4734
4724 4735 // Scan strong roots in mark stack.
4725 4736 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4726 4737 concurrent_mark()->oops_do(scan_non_heap_roots);
4727 4738 }
4728 4739 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4729 4740 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4730 4741
4731 4742 // XXX What should this be doing in the parallel case?
4732 4743 g1_policy()->record_collection_pause_end_CH_strong_roots();
4733 4744 // Now scan the complement of the collection set.
4734 4745 if (scan_rs != NULL) {
4735 4746 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4736 4747 }
4737 4748 // Finish with the ref_processor roots.
4738 4749 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4739 4750 // We need to treat the discovered reference lists as roots and
4740 4751 // keep entries (which are added by the marking threads) on them
4741 4752 // live until they can be processed at the end of marking.
4742 4753 ref_processor()->weak_oops_do(scan_non_heap_roots);
4743 4754 ref_processor()->oops_do(scan_non_heap_roots);
4744 4755 }
4745 4756 g1_policy()->record_collection_pause_end_G1_strong_roots();
4746 4757 _process_strong_tasks->all_tasks_completed();
4747 4758 }
4748 4759
4749 4760 void
4750 4761 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4751 4762 OopClosure* non_root_closure) {
4752 4763 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4753 4764 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4754 4765 }
4755 4766
4756 4767
4757 4768 class SaveMarksClosure: public HeapRegionClosure {
4758 4769 public:
4759 4770 bool doHeapRegion(HeapRegion* r) {
4760 4771 r->save_marks();
4761 4772 return false;
4762 4773 }
4763 4774 };
4764 4775
4765 4776 void G1CollectedHeap::save_marks() {
4766 4777 if (!CollectedHeap::use_parallel_gc_threads()) {
4767 4778 SaveMarksClosure sm;
4768 4779 heap_region_iterate(&sm);
4769 4780 }
4770 4781 // We do this even in the parallel case
4771 4782 perm_gen()->save_marks();
4772 4783 }
4773 4784
4774 4785 void G1CollectedHeap::evacuate_collection_set() {
4775 4786 set_evacuation_failed(false);
4776 4787
4777 4788 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4778 4789 concurrent_g1_refine()->set_use_cache(false);
4779 4790 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4780 4791
4781 4792 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4782 4793 set_par_threads(n_workers);
4783 4794 G1ParTask g1_par_task(this, n_workers, _task_queues);
4784 4795
4785 4796 init_for_evac_failure(NULL);
4786 4797
4787 4798 rem_set()->prepare_for_younger_refs_iterate(true);
4788 4799
4789 4800 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4790 4801 double start_par = os::elapsedTime();
4791 4802 if (G1CollectedHeap::use_parallel_gc_threads()) {
4792 4803 // The individual threads will set their evac-failure closures.
4793 4804 StrongRootsScope srs(this);
4794 4805 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4795 4806 workers()->run_task(&g1_par_task);
4796 4807 } else {
4797 4808 StrongRootsScope srs(this);
4798 4809 g1_par_task.work(0);
4799 4810 }
4800 4811
4801 4812 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4802 4813 g1_policy()->record_par_time(par_time);
4803 4814 set_par_threads(0);
4804 4815 // Is this the right thing to do here? We don't save marks
4805 4816 // on individual heap regions when we allocate from
4806 4817 // them in parallel, so this seems like the correct place for this.
4807 4818 retire_all_alloc_regions();
4808 4819
4809 4820 // Weak root processing.
4810 4821 // Note: when JSR 292 is enabled and code blobs can contain
4811 4822 // non-perm oops then we will need to process the code blobs
4812 4823 // here too.
4813 4824 {
4814 4825 G1IsAliveClosure is_alive(this);
4815 4826 G1KeepAliveClosure keep_alive(this);
4816 4827 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4817 4828 }
4818 4829 release_gc_alloc_regions(false /* totally */);
4819 4830 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4820 4831
4821 4832 concurrent_g1_refine()->clear_hot_cache();
4822 4833 concurrent_g1_refine()->set_use_cache(true);
4823 4834
4824 4835 finalize_for_evac_failure();
4825 4836
4826 4837 // Must do this before removing self-forwarding pointers, which clears
4827 4838 // the per-region evac-failure flags.
4828 4839 concurrent_mark()->complete_marking_in_collection_set();
4829 4840
4830 4841 if (evacuation_failed()) {
4831 4842 remove_self_forwarding_pointers();
4832 4843 if (PrintGCDetails) {
4833 4844 gclog_or_tty->print(" (to-space overflow)");
4834 4845 } else if (PrintGC) {
4835 4846 gclog_or_tty->print("--");
4836 4847 }
4837 4848 }
4838 4849
4839 4850 if (G1DeferredRSUpdate) {
4840 4851 RedirtyLoggedCardTableEntryFastClosure redirty;
4841 4852 dirty_card_queue_set().set_closure(&redirty);
4842 4853 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4843 4854
4844 4855 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4845 4856 dcq.merge_bufferlists(&dirty_card_queue_set());
4846 4857 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4847 4858 }
4848 4859 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4849 4860 }
4850 4861
4851 4862 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
4852 4863 size_t* pre_used,
4853 4864 FreeRegionList* free_list,
4854 4865 HumongousRegionSet* humongous_proxy_set,
4855 4866 HRRSCleanupTask* hrrs_cleanup_task,
4856 4867 bool par) {
4857 4868 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
4858 4869 if (hr->isHumongous()) {
4859 4870 assert(hr->startsHumongous(), "we should only see starts humongous");
4860 4871 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
4861 4872 } else {
4862 4873 free_region(hr, pre_used, free_list, par);
4863 4874 }
4864 4875 } else {
4865 4876 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
4866 4877 }
4867 4878 }
4868 4879
4869 4880 void G1CollectedHeap::free_region(HeapRegion* hr,
4870 4881 size_t* pre_used,
4871 4882 FreeRegionList* free_list,
4872 4883 bool par) {
4873 4884 assert(!hr->isHumongous(), "this is only for non-humongous regions");
4874 4885 assert(!hr->is_empty(), "the region should not be empty");
4875 4886 assert(free_list != NULL, "pre-condition");
4876 4887
4877 4888 *pre_used += hr->used();
4878 4889 hr->hr_clear(par, true /* clear_space */);
4879 4890 free_list->add_as_head(hr);
4880 4891 }
4881 4892
4882 4893 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4883 4894 size_t* pre_used,
4884 4895 FreeRegionList* free_list,
4885 4896 HumongousRegionSet* humongous_proxy_set,
4886 4897 bool par) {
4887 4898 assert(hr->startsHumongous(), "this is only for starts humongous regions");
4888 4899 assert(free_list != NULL, "pre-condition");
4889 4900 assert(humongous_proxy_set != NULL, "pre-condition");
4890 4901
4891 4902 size_t hr_used = hr->used();
4892 4903 size_t hr_capacity = hr->capacity();
4893 4904 size_t hr_pre_used = 0;
4894 4905 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
4895 4906 hr->set_notHumongous();
4896 4907 free_region(hr, &hr_pre_used, free_list, par);
4897 4908
4898 4909 int i = hr->hrs_index() + 1;
4899 4910 size_t num = 1;
4900 4911 while ((size_t) i < n_regions()) {
4901 4912 HeapRegion* curr_hr = _hrs->at(i);
4902 4913 if (!curr_hr->continuesHumongous()) {
4903 4914 break;
4904 4915 }
4905 4916 curr_hr->set_notHumongous();
4906 4917 free_region(curr_hr, &hr_pre_used, free_list, par);
4907 4918 num += 1;
4908 4919 i += 1;
4909 4920 }
4910 4921 assert(hr_pre_used == hr_used,
4911 4922 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
4912 4923 "should be the same", hr_pre_used, hr_used));
4913 4924 *pre_used += hr_pre_used;
4914 4925 }
4915 4926
4916 4927 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
4917 4928 FreeRegionList* free_list,
4918 4929 HumongousRegionSet* humongous_proxy_set,
4919 4930 bool par) {
4920 4931 if (pre_used > 0) {
4921 4932 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
4922 4933 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4923 4934 assert(_summary_bytes_used >= pre_used,
4924 4935 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
4925 4936 "should be >= pre_used: "SIZE_FORMAT,
4926 4937 _summary_bytes_used, pre_used));
4927 4938 _summary_bytes_used -= pre_used;
4928 4939 }
4929 4940 if (free_list != NULL && !free_list->is_empty()) {
4930 4941 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4931 4942 _free_list.add_as_head(free_list);
4932 4943 }
4933 4944 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
4934 4945 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4935 4946 _humongous_set.update_from_proxy(humongous_proxy_set);
4936 4947 }
4937 4948 }
4938 4949
4939 4950 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4940 4951 while (list != NULL) {
4941 4952 guarantee( list->is_young(), "invariant" );
4942 4953
4943 4954 HeapWord* bottom = list->bottom();
4944 4955 HeapWord* end = list->end();
4945 4956 MemRegion mr(bottom, end);
4946 4957 ct_bs->dirty(mr);
4947 4958
4948 4959 list = list->get_next_young_region();
4949 4960 }
4950 4961 }
4951 4962
4952 4963
4953 4964 class G1ParCleanupCTTask : public AbstractGangTask {
4954 4965 CardTableModRefBS* _ct_bs;
4955 4966 G1CollectedHeap* _g1h;
4956 4967 HeapRegion* volatile _su_head;
4957 4968 public:
4958 4969 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4959 4970 G1CollectedHeap* g1h,
4960 4971 HeapRegion* survivor_list) :
4961 4972 AbstractGangTask("G1 Par Cleanup CT Task"),
4962 4973 _ct_bs(ct_bs),
4963 4974 _g1h(g1h),
4964 4975 _su_head(survivor_list)
4965 4976 { }
4966 4977
4967 4978 void work(int i) {
4968 4979 HeapRegion* r;
4969 4980 while (r = _g1h->pop_dirty_cards_region()) {
4970 4981 clear_cards(r);
4971 4982 }
4972 4983 // Redirty the cards of the survivor regions.
4973 4984 dirty_list(&this->_su_head);
4974 4985 }
4975 4986
4976 4987 void clear_cards(HeapRegion* r) {
4977 4988 // Cards for Survivor regions will be dirtied later.
4978 4989 if (!r->is_survivor()) {
4979 4990 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4980 4991 }
4981 4992 }
4982 4993
4983 4994 void dirty_list(HeapRegion* volatile * head_ptr) {
4984 4995 HeapRegion* head;
4985 4996 do {
4986 4997 // Pop region off the list.
4987 4998 head = *head_ptr;
4988 4999 if (head != NULL) {
4989 5000 HeapRegion* r = (HeapRegion*)
4990 5001 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4991 5002 if (r == head) {
4992 5003 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4993 5004 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4994 5005 }
4995 5006 }
4996 5007 } while (*head_ptr != NULL);
4997 5008 }
4998 5009 };
4999 5010
5000 5011
5001 5012 #ifndef PRODUCT
5002 5013 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5003 5014 G1CollectedHeap* _g1h;
5004 5015 CardTableModRefBS* _ct_bs;
5005 5016 public:
5006 5017 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5007 5018 : _g1h(g1h), _ct_bs(ct_bs) { }
5008 5019 virtual bool doHeapRegion(HeapRegion* r) {
5009 5020 if (r->is_survivor()) {
5010 5021 _g1h->verify_dirty_region(r);
5011 5022 } else {
5012 5023 _g1h->verify_not_dirty_region(r);
5013 5024 }
5014 5025 return false;
5015 5026 }
5016 5027 };
5017 5028
5018 5029 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5019 5030 // All of the region should be clean.
5020 5031 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5021 5032 MemRegion mr(hr->bottom(), hr->end());
5022 5033 ct_bs->verify_not_dirty_region(mr);
5023 5034 }
5024 5035
5025 5036 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5026 5037 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5027 5038 // dirty allocated blocks as they allocate them. The thread that
5028 5039 // retires each region and replaces it with a new one will do a
5029 5040 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5030 5041 // not dirty that area (one less thing to have to do while holding
5031 5042 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5032 5043 // is dirty.
5033 5044 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5034 5045 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5035 5046 ct_bs->verify_dirty_region(mr);
5036 5047 }
5037 5048
5038 5049 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5039 5050 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5040 5051 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5041 5052 verify_dirty_region(hr);
5042 5053 }
5043 5054 }
5044 5055
5045 5056 void G1CollectedHeap::verify_dirty_young_regions() {
5046 5057 verify_dirty_young_list(_young_list->first_region());
5047 5058 verify_dirty_young_list(_young_list->first_survivor_region());
5048 5059 }
5049 5060 #endif
5050 5061
5051 5062 void G1CollectedHeap::cleanUpCardTable() {
5052 5063 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5053 5064 double start = os::elapsedTime();
5054 5065
5055 5066 // Iterate over the dirty cards region list.
5056 5067 G1ParCleanupCTTask cleanup_task(ct_bs, this,
5057 5068 _young_list->first_survivor_region());
5058 5069
5059 5070 if (ParallelGCThreads > 0) {
5060 5071 set_par_threads(workers()->total_workers());
5061 5072 workers()->run_task(&cleanup_task);
5062 5073 set_par_threads(0);
5063 5074 } else {
5064 5075 while (_dirty_cards_region_list) {
5065 5076 HeapRegion* r = _dirty_cards_region_list;
5066 5077 cleanup_task.clear_cards(r);
5067 5078 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5068 5079 if (_dirty_cards_region_list == r) {
5069 5080 // The last region.
5070 5081 _dirty_cards_region_list = NULL;
5071 5082 }
5072 5083 r->set_next_dirty_cards_region(NULL);
5073 5084 }
5074 5085 // now, redirty the cards of the survivor regions
5075 5086 // (it seemed faster to do it this way, instead of iterating over
5076 5087 // all regions and then clearing / dirtying as appropriate)
5077 5088 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
5078 5089 }
5079 5090
5080 5091 double elapsed = os::elapsedTime() - start;
5081 5092 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
5082 5093 #ifndef PRODUCT
5083 5094 if (G1VerifyCTCleanup || VerifyAfterGC) {
5084 5095 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5085 5096 heap_region_iterate(&cleanup_verifier);
5086 5097 }
5087 5098 #endif
5088 5099 }
5089 5100
5090 5101 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5091 5102 size_t pre_used = 0;
5092 5103 FreeRegionList local_free_list("Local List for CSet Freeing");
5093 5104
5094 5105 double young_time_ms = 0.0;
5095 5106 double non_young_time_ms = 0.0;
5096 5107
5097 5108 // Since the collection set is a superset of the the young list,
5098 5109 // all we need to do to clear the young list is clear its
5099 5110 // head and length, and unlink any young regions in the code below
5100 5111 _young_list->clear();
5101 5112
5102 5113 G1CollectorPolicy* policy = g1_policy();
5103 5114
5104 5115 double start_sec = os::elapsedTime();
5105 5116 bool non_young = true;
5106 5117
5107 5118 HeapRegion* cur = cs_head;
5108 5119 int age_bound = -1;
5109 5120 size_t rs_lengths = 0;
5110 5121
5111 5122 while (cur != NULL) {
5112 5123 assert(!is_on_master_free_list(cur), "sanity");
5113 5124
5114 5125 if (non_young) {
5115 5126 if (cur->is_young()) {
5116 5127 double end_sec = os::elapsedTime();
5117 5128 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5118 5129 non_young_time_ms += elapsed_ms;
5119 5130
5120 5131 start_sec = os::elapsedTime();
5121 5132 non_young = false;
5122 5133 }
5123 5134 } else {
5124 5135 double end_sec = os::elapsedTime();
5125 5136 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5126 5137 young_time_ms += elapsed_ms;
5127 5138
5128 5139 start_sec = os::elapsedTime();
5129 5140 non_young = true;
5130 5141 }
5131 5142
5132 5143 rs_lengths += cur->rem_set()->occupied();
5133 5144
5134 5145 HeapRegion* next = cur->next_in_collection_set();
5135 5146 assert(cur->in_collection_set(), "bad CS");
5136 5147 cur->set_next_in_collection_set(NULL);
5137 5148 cur->set_in_collection_set(false);
5138 5149
5139 5150 if (cur->is_young()) {
5140 5151 int index = cur->young_index_in_cset();
5141 5152 guarantee( index != -1, "invariant" );
5142 5153 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
5143 5154 size_t words_survived = _surviving_young_words[index];
5144 5155 cur->record_surv_words_in_group(words_survived);
5145 5156
5146 5157 // At this point the we have 'popped' cur from the collection set
5147 5158 // (linked via next_in_collection_set()) but it is still in the
5148 5159 // young list (linked via next_young_region()). Clear the
5149 5160 // _next_young_region field.
5150 5161 cur->set_next_young_region(NULL);
5151 5162 } else {
5152 5163 int index = cur->young_index_in_cset();
5153 5164 guarantee( index == -1, "invariant" );
5154 5165 }
5155 5166
5156 5167 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5157 5168 (!cur->is_young() && cur->young_index_in_cset() == -1),
5158 5169 "invariant" );
5159 5170
5160 5171 if (!cur->evacuation_failed()) {
5161 5172 // And the region is empty.
5162 5173 assert(!cur->is_empty(), "Should not have empty regions in a CS.");
5163 5174 free_region(cur, &pre_used, &local_free_list, false /* par */);
5164 5175 } else {
5165 5176 cur->uninstall_surv_rate_group();
5166 5177 if (cur->is_young())
5167 5178 cur->set_young_index_in_cset(-1);
5168 5179 cur->set_not_young();
5169 5180 cur->set_evacuation_failed(false);
5170 5181 }
5171 5182 cur = next;
5172 5183 }
5173 5184
5174 5185 policy->record_max_rs_lengths(rs_lengths);
5175 5186 policy->cset_regions_freed();
5176 5187
5177 5188 double end_sec = os::elapsedTime();
5178 5189 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5179 5190 if (non_young)
5180 5191 non_young_time_ms += elapsed_ms;
5181 5192 else
5182 5193 young_time_ms += elapsed_ms;
5183 5194
5184 5195 update_sets_after_freeing_regions(pre_used, &local_free_list,
5185 5196 NULL /* humongous_proxy_set */,
5186 5197 false /* par */);
5187 5198 policy->record_young_free_cset_time_ms(young_time_ms);
5188 5199 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5189 5200 }
5190 5201
5191 5202 // This routine is similar to the above but does not record
5192 5203 // any policy statistics or update free lists; we are abandoning
5193 5204 // the current incremental collection set in preparation of a
5194 5205 // full collection. After the full GC we will start to build up
5195 5206 // the incremental collection set again.
5196 5207 // This is only called when we're doing a full collection
5197 5208 // and is immediately followed by the tearing down of the young list.
5198 5209
5199 5210 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5200 5211 HeapRegion* cur = cs_head;
5201 5212
5202 5213 while (cur != NULL) {
5203 5214 HeapRegion* next = cur->next_in_collection_set();
5204 5215 assert(cur->in_collection_set(), "bad CS");
5205 5216 cur->set_next_in_collection_set(NULL);
5206 5217 cur->set_in_collection_set(false);
5207 5218 cur->set_young_index_in_cset(-1);
5208 5219 cur = next;
5209 5220 }
5210 5221 }
5211 5222
5212 5223 void G1CollectedHeap::set_free_regions_coming() {
5213 5224 if (G1ConcRegionFreeingVerbose) {
5214 5225 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5215 5226 "setting free regions coming");
5216 5227 }
5217 5228
5218 5229 assert(!free_regions_coming(), "pre-condition");
5219 5230 _free_regions_coming = true;
5220 5231 }
5221 5232
5222 5233 void G1CollectedHeap::reset_free_regions_coming() {
5223 5234 {
5224 5235 assert(free_regions_coming(), "pre-condition");
5225 5236 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5226 5237 _free_regions_coming = false;
5227 5238 SecondaryFreeList_lock->notify_all();
5228 5239 }
5229 5240
5230 5241 if (G1ConcRegionFreeingVerbose) {
5231 5242 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5232 5243 "reset free regions coming");
5233 5244 }
5234 5245 }
5235 5246
5236 5247 void G1CollectedHeap::wait_while_free_regions_coming() {
5237 5248 // Most of the time we won't have to wait, so let's do a quick test
5238 5249 // first before we take the lock.
5239 5250 if (!free_regions_coming()) {
5240 5251 return;
5241 5252 }
5242 5253
5243 5254 if (G1ConcRegionFreeingVerbose) {
5244 5255 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5245 5256 "waiting for free regions");
5246 5257 }
5247 5258
5248 5259 {
5249 5260 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5250 5261 while (free_regions_coming()) {
5251 5262 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5252 5263 }
5253 5264 }
5254 5265
5255 5266 if (G1ConcRegionFreeingVerbose) {
5256 5267 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5257 5268 "done waiting for free regions");
5258 5269 }
5259 5270 }
5260 5271
5261 5272 size_t G1CollectedHeap::n_regions() {
5262 5273 return _hrs->length();
5263 5274 }
5264 5275
5265 5276 size_t G1CollectedHeap::max_regions() {
5266 5277 return
5267 5278 (size_t)align_size_up(max_capacity(), HeapRegion::GrainBytes) /
5268 5279 HeapRegion::GrainBytes;
5269 5280 }
5270 5281
5271 5282 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5272 5283 assert(heap_lock_held_for_gc(),
5273 5284 "the heap lock should already be held by or for this thread");
5274 5285 _young_list->push_region(hr);
5275 5286 g1_policy()->set_region_short_lived(hr);
5276 5287 }
5277 5288
5278 5289 class NoYoungRegionsClosure: public HeapRegionClosure {
5279 5290 private:
5280 5291 bool _success;
5281 5292 public:
5282 5293 NoYoungRegionsClosure() : _success(true) { }
5283 5294 bool doHeapRegion(HeapRegion* r) {
5284 5295 if (r->is_young()) {
5285 5296 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5286 5297 r->bottom(), r->end());
5287 5298 _success = false;
5288 5299 }
5289 5300 return false;
5290 5301 }
5291 5302 bool success() { return _success; }
5292 5303 };
5293 5304
5294 5305 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5295 5306 bool ret = _young_list->check_list_empty(check_sample);
5296 5307
5297 5308 if (check_heap) {
5298 5309 NoYoungRegionsClosure closure;
5299 5310 heap_region_iterate(&closure);
5300 5311 ret = ret && closure.success();
5301 5312 }
5302 5313
5303 5314 return ret;
5304 5315 }
5305 5316
5306 5317 void G1CollectedHeap::empty_young_list() {
5307 5318 assert(heap_lock_held_for_gc(),
5308 5319 "the heap lock should already be held by or for this thread");
5309 5320 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5310 5321
5311 5322 _young_list->empty_list();
5312 5323 }
5313 5324
5314 5325 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5315 5326 bool no_allocs = true;
5316 5327 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5317 5328 HeapRegion* r = _gc_alloc_regions[ap];
5318 5329 no_allocs = r == NULL || r->saved_mark_at_top();
5319 5330 }
5320 5331 return no_allocs;
5321 5332 }
5322 5333
5323 5334 void G1CollectedHeap::retire_all_alloc_regions() {
5324 5335 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5325 5336 HeapRegion* r = _gc_alloc_regions[ap];
5326 5337 if (r != NULL) {
5327 5338 // Check for aliases.
5328 5339 bool has_processed_alias = false;
5329 5340 for (int i = 0; i < ap; ++i) {
5330 5341 if (_gc_alloc_regions[i] == r) {
5331 5342 has_processed_alias = true;
5332 5343 break;
5333 5344 }
5334 5345 }
5335 5346 if (!has_processed_alias) {
5336 5347 retire_alloc_region(r, false /* par */);
5337 5348 }
5338 5349 }
5339 5350 }
5340 5351 }
5341 5352
5342 5353 // Done at the start of full GC.
5343 5354 void G1CollectedHeap::tear_down_region_lists() {
5344 5355 _free_list.remove_all();
5345 5356 }
5346 5357
5347 5358 class RegionResetter: public HeapRegionClosure {
5348 5359 G1CollectedHeap* _g1h;
5349 5360 FreeRegionList _local_free_list;
5350 5361
5351 5362 public:
5352 5363 RegionResetter() : _g1h(G1CollectedHeap::heap()),
5353 5364 _local_free_list("Local Free List for RegionResetter") { }
5354 5365
5355 5366 bool doHeapRegion(HeapRegion* r) {
5356 5367 if (r->continuesHumongous()) return false;
5357 5368 if (r->top() > r->bottom()) {
5358 5369 if (r->top() < r->end()) {
5359 5370 Copy::fill_to_words(r->top(),
5360 5371 pointer_delta(r->end(), r->top()));
5361 5372 }
5362 5373 } else {
5363 5374 assert(r->is_empty(), "tautology");
5364 5375 _local_free_list.add_as_tail(r);
5365 5376 }
5366 5377 return false;
5367 5378 }
5368 5379
5369 5380 void update_free_lists() {
5370 5381 _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL,
5371 5382 false /* par */);
5372 5383 }
5373 5384 };
5374 5385
5375 5386 // Done at the end of full GC.
5376 5387 void G1CollectedHeap::rebuild_region_lists() {
5377 5388 // This needs to go at the end of the full GC.
5378 5389 RegionResetter rs;
5379 5390 heap_region_iterate(&rs);
5380 5391 rs.update_free_lists();
5381 5392 }
5382 5393
5383 5394 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5384 5395 _refine_cte_cl->set_concurrent(concurrent);
5385 5396 }
5386 5397
5387 5398 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5388 5399 HeapRegion* hr = heap_region_containing(p);
5389 5400 if (hr == NULL) {
5390 5401 return is_in_permanent(p);
5391 5402 } else {
5392 5403 return hr->is_in(p);
5393 5404 }
5394 5405 }
5395 5406
5396 5407 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5397 5408 bool force) {
5398 5409 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5399 5410 assert(!force || g1_policy()->can_expand_young_list(),
5400 5411 "if force is true we should be able to expand the young list");
5401 5412 if (force || !g1_policy()->is_young_list_full()) {
5402 5413 HeapRegion* new_alloc_region = new_region(word_size,
5403 5414 false /* do_expand */);
5404 5415 if (new_alloc_region != NULL) {
5405 5416 g1_policy()->update_region_num(true /* next_is_young */);
5406 5417 set_region_short_lived_locked(new_alloc_region);
5407 5418 g1mm()->update_eden_counters();
5408 5419 return new_alloc_region;
5409 5420 }
5410 5421 }
5411 5422 return NULL;
5412 5423 }
5413 5424
5414 5425 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5415 5426 size_t allocated_bytes) {
5416 5427 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5417 5428 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
5418 5429
5419 5430 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5420 5431 _summary_bytes_used += allocated_bytes;
5421 5432 }
5422 5433
5423 5434 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
5424 5435 bool force) {
5425 5436 return _g1h->new_mutator_alloc_region(word_size, force);
5426 5437 }
5427 5438
5428 5439 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
5429 5440 size_t allocated_bytes) {
5430 5441 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
5431 5442 }
5432 5443
5433 5444 // Heap region set verification
5434 5445
5435 5446 class VerifyRegionListsClosure : public HeapRegionClosure {
5436 5447 private:
5437 5448 HumongousRegionSet* _humongous_set;
5438 5449 FreeRegionList* _free_list;
5439 5450 size_t _region_count;
5440 5451
5441 5452 public:
5442 5453 VerifyRegionListsClosure(HumongousRegionSet* humongous_set,
5443 5454 FreeRegionList* free_list) :
5444 5455 _humongous_set(humongous_set), _free_list(free_list),
5445 5456 _region_count(0) { }
5446 5457
5447 5458 size_t region_count() { return _region_count; }
5448 5459
5449 5460 bool doHeapRegion(HeapRegion* hr) {
5450 5461 _region_count += 1;
5451 5462
5452 5463 if (hr->continuesHumongous()) {
5453 5464 return false;
5454 5465 }
5455 5466
5456 5467 if (hr->is_young()) {
5457 5468 // TODO
5458 5469 } else if (hr->startsHumongous()) {
5459 5470 _humongous_set->verify_next_region(hr);
5460 5471 } else if (hr->is_empty()) {
5461 5472 _free_list->verify_next_region(hr);
5462 5473 }
5463 5474 return false;
5464 5475 }
5465 5476 };
5466 5477
5467 5478 void G1CollectedHeap::verify_region_sets() {
5468 5479 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5469 5480
5470 5481 // First, check the explicit lists.
5471 5482 _free_list.verify();
5472 5483 {
5473 5484 // Given that a concurrent operation might be adding regions to
5474 5485 // the secondary free list we have to take the lock before
5475 5486 // verifying it.
5476 5487 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5477 5488 _secondary_free_list.verify();
5478 5489 }
5479 5490 _humongous_set.verify();
5480 5491
5481 5492 // If a concurrent region freeing operation is in progress it will
5482 5493 // be difficult to correctly attributed any free regions we come
5483 5494 // across to the correct free list given that they might belong to
5484 5495 // one of several (free_list, secondary_free_list, any local lists,
5485 5496 // etc.). So, if that's the case we will skip the rest of the
5486 5497 // verification operation. Alternatively, waiting for the concurrent
5487 5498 // operation to complete will have a non-trivial effect on the GC's
5488 5499 // operation (no concurrent operation will last longer than the
5489 5500 // interval between two calls to verification) and it might hide
5490 5501 // any issues that we would like to catch during testing.
5491 5502 if (free_regions_coming()) {
5492 5503 return;
5493 5504 }
5494 5505
5495 5506 // Make sure we append the secondary_free_list on the free_list so
5496 5507 // that all free regions we will come across can be safely
5497 5508 // attributed to the free_list.
5498 5509 append_secondary_free_list_if_not_empty_with_lock();
5499 5510
5500 5511 // Finally, make sure that the region accounting in the lists is
5501 5512 // consistent with what we see in the heap.
5502 5513 _humongous_set.verify_start();
5503 5514 _free_list.verify_start();
5504 5515
5505 5516 VerifyRegionListsClosure cl(&_humongous_set, &_free_list);
5506 5517 heap_region_iterate(&cl);
5507 5518
5508 5519 _humongous_set.verify_end();
5509 5520 _free_list.verify_end();
5510 5521 }
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