1 /*
2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/shared/gcTimer.hpp"
27 #include "gc_implementation/shared/gcTrace.hpp"
28 #include "gc_implementation/shared/spaceDecorator.hpp"
29 #include "gc_interface/collectedHeap.inline.hpp"
30 #include "memory/allocation.inline.hpp"
31 #include "memory/blockOffsetTable.inline.hpp"
32 #include "memory/cardTableRS.hpp"
33 #include "memory/gcLocker.inline.hpp"
34 #include "memory/genCollectedHeap.hpp"
35 #include "memory/genMarkSweep.hpp"
36 #include "memory/genOopClosures.hpp"
37 #include "memory/genOopClosures.inline.hpp"
38 #include "memory/generation.hpp"
39 #include "memory/generation.inline.hpp"
40 #include "memory/space.inline.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "runtime/java.hpp"
43 #include "utilities/copy.hpp"
44 #include "utilities/events.hpp"
45
46 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
47
48 Generation::Generation(ReservedSpace rs, size_t initial_size, int level) :
49 _level(level),
50 _ref_processor(NULL) {
51 if (!_virtual_space.initialize(rs, initial_size)) {
52 vm_exit_during_initialization("Could not reserve enough space for "
53 "object heap");
54 }
55 // Mangle all of the the initial generation.
56 if (ZapUnusedHeapArea) {
57 MemRegion mangle_region((HeapWord*)_virtual_space.low(),
58 (HeapWord*)_virtual_space.high());
59 SpaceMangler::mangle_region(mangle_region);
60 }
61 _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),
62 (HeapWord*)_virtual_space.high_boundary());
63 }
64
65 GenerationSpec* Generation::spec() {
66 GenCollectedHeap* gch = GenCollectedHeap::heap();
67 assert(0 <= level() && level() < gch->_n_gens, "Bad gen level");
68 return gch->_gen_specs[level()];
69 }
70
71 size_t Generation::max_capacity() const {
72 return reserved().byte_size();
73 }
74
75 void Generation::print_heap_change(size_t prev_used) const {
76 if (PrintGCDetails && Verbose) {
77 gclog_or_tty->print(" " SIZE_FORMAT
78 "->" SIZE_FORMAT
79 "(" SIZE_FORMAT ")",
80 prev_used, used(), capacity());
81 } else {
82 gclog_or_tty->print(" " SIZE_FORMAT "K"
83 "->" SIZE_FORMAT "K"
84 "(" SIZE_FORMAT "K)",
85 prev_used / K, used() / K, capacity() / K);
86 }
87 }
88
89 // By default we get a single threaded default reference processor;
90 // generations needing multi-threaded refs processing or discovery override this method.
91 void Generation::ref_processor_init() {
92 assert(_ref_processor == NULL, "a reference processor already exists");
93 assert(!_reserved.is_empty(), "empty generation?");
94 _ref_processor = new ReferenceProcessor(_reserved); // a vanilla reference processor
95 if (_ref_processor == NULL) {
96 vm_exit_during_initialization("Could not allocate ReferenceProcessor object");
97 }
98 }
99
100 void Generation::print() const { print_on(tty); }
101
102 void Generation::print_on(outputStream* st) const {
103 st->print(" %-20s", name());
104 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
105 capacity()/K, used()/K);
106 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
107 _virtual_space.low_boundary(),
108 _virtual_space.high(),
109 _virtual_space.high_boundary());
110 }
111
112 void Generation::print_summary_info() { print_summary_info_on(tty); }
113
114 void Generation::print_summary_info_on(outputStream* st) {
115 StatRecord* sr = stat_record();
116 double time = sr->accumulated_time.seconds();
117 st->print_cr("[Accumulated GC generation %d time %3.7f secs, "
118 "%d GC's, avg GC time %3.7f]",
119 level(), time, sr->invocations,
120 sr->invocations > 0 ? time / sr->invocations : 0.0);
121 }
122
123 // Utility iterator classes
124
125 class GenerationIsInReservedClosure : public SpaceClosure {
126 public:
127 const void* _p;
128 Space* sp;
129 virtual void do_space(Space* s) {
130 if (sp == NULL) {
131 if (s->is_in_reserved(_p)) sp = s;
132 }
133 }
134 GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {}
135 };
136
137 class GenerationIsInClosure : public SpaceClosure {
138 public:
139 const void* _p;
140 Space* sp;
141 virtual void do_space(Space* s) {
142 if (sp == NULL) {
143 if (s->is_in(_p)) sp = s;
144 }
145 }
146 GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {}
147 };
148
149 bool Generation::is_in(const void* p) const {
150 GenerationIsInClosure blk(p);
151 ((Generation*)this)->space_iterate(&blk);
152 return blk.sp != NULL;
153 }
154
155 DefNewGeneration* Generation::as_DefNewGeneration() {
156 assert((kind() == Generation::DefNew) ||
157 (kind() == Generation::ParNew),
158 "Wrong youngest generation type");
159 return (DefNewGeneration*) this;
160 }
161
162 Generation* Generation::next_gen() const {
163 GenCollectedHeap* gch = GenCollectedHeap::heap();
164 int next = level() + 1;
165 if (next < gch->_n_gens) {
166 return gch->_gens[next];
167 } else {
168 return NULL;
169 }
170 }
171
172 size_t Generation::max_contiguous_available() const {
173 // The largest number of contiguous free words in this or any higher generation.
174 size_t max = 0;
175 for (const Generation* gen = this; gen != NULL; gen = gen->next_gen()) {
176 size_t avail = gen->contiguous_available();
177 if (avail > max) {
178 max = avail;
179 }
180 }
181 return max;
182 }
183
184 bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
185 size_t available = max_contiguous_available();
186 bool res = (available >= max_promotion_in_bytes);
187 if (PrintGC && Verbose) {
188 gclog_or_tty->print_cr(
189 "Generation: promo attempt is%s safe: available("SIZE_FORMAT") %s max_promo("SIZE_FORMAT")",
190 res? "":" not", available, res? ">=":"<",
191 max_promotion_in_bytes);
192 }
193 return res;
194 }
195
196 // Ignores "ref" and calls allocate().
197 oop Generation::promote(oop obj, size_t obj_size) {
198 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
199
200 #ifndef PRODUCT
201 if (Universe::heap()->promotion_should_fail()) {
202 return NULL;
203 }
204 #endif // #ifndef PRODUCT
205
206 HeapWord* result = allocate(obj_size, false);
207 if (result != NULL) {
208 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
209 return oop(result);
210 } else {
211 GenCollectedHeap* gch = GenCollectedHeap::heap();
212 return gch->handle_failed_promotion(this, obj, obj_size);
213 }
214 }
215
216 oop Generation::par_promote(int thread_num,
217 oop obj, markOop m, size_t word_sz) {
218 // Could do a bad general impl here that gets a lock. But no.
219 ShouldNotCallThis();
220 return NULL;
221 }
222
223 Space* Generation::space_containing(const void* p) const {
224 GenerationIsInReservedClosure blk(p);
225 // Cast away const
226 ((Generation*)this)->space_iterate(&blk);
227 return blk.sp;
228 }
229
230 // Some of these are mediocre general implementations. Should be
231 // overridden to get better performance.
232
233 class GenerationBlockStartClosure : public SpaceClosure {
234 public:
235 const void* _p;
236 HeapWord* _start;
237 virtual void do_space(Space* s) {
238 if (_start == NULL && s->is_in_reserved(_p)) {
239 _start = s->block_start(_p);
240 }
241 }
242 GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; }
243 };
244
245 HeapWord* Generation::block_start(const void* p) const {
246 GenerationBlockStartClosure blk(p);
247 // Cast away const
248 ((Generation*)this)->space_iterate(&blk);
249 return blk._start;
250 }
251
252 class GenerationBlockSizeClosure : public SpaceClosure {
253 public:
254 const HeapWord* _p;
255 size_t size;
256 virtual void do_space(Space* s) {
257 if (size == 0 && s->is_in_reserved(_p)) {
258 size = s->block_size(_p);
259 }
260 }
261 GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; }
262 };
263
264 size_t Generation::block_size(const HeapWord* p) const {
265 GenerationBlockSizeClosure blk(p);
266 // Cast away const
267 ((Generation*)this)->space_iterate(&blk);
268 assert(blk.size > 0, "seems reasonable");
269 return blk.size;
270 }
271
272 class GenerationBlockIsObjClosure : public SpaceClosure {
273 public:
274 const HeapWord* _p;
275 bool is_obj;
276 virtual void do_space(Space* s) {
277 if (!is_obj && s->is_in_reserved(_p)) {
278 is_obj |= s->block_is_obj(_p);
279 }
280 }
281 GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; }
282 };
283
284 bool Generation::block_is_obj(const HeapWord* p) const {
285 GenerationBlockIsObjClosure blk(p);
286 // Cast away const
287 ((Generation*)this)->space_iterate(&blk);
288 return blk.is_obj;
289 }
290
291 class GenerationOopIterateClosure : public SpaceClosure {
292 public:
293 ExtendedOopClosure* _cl;
294 virtual void do_space(Space* s) {
295 s->oop_iterate(_cl);
296 }
297 GenerationOopIterateClosure(ExtendedOopClosure* cl) :
298 _cl(cl) {}
299 };
300
301 void Generation::oop_iterate(ExtendedOopClosure* cl) {
302 GenerationOopIterateClosure blk(cl);
303 space_iterate(&blk);
304 }
305
306 void Generation::younger_refs_in_space_iterate(Space* sp,
307 OopsInGenClosure* cl) {
308 GenRemSet* rs = SharedHeap::heap()->rem_set();
309 rs->younger_refs_in_space_iterate(sp, cl);
310 }
311
312 class GenerationObjIterateClosure : public SpaceClosure {
313 private:
314 ObjectClosure* _cl;
315 public:
316 virtual void do_space(Space* s) {
317 s->object_iterate(_cl);
318 }
319 GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
320 };
321
322 void Generation::object_iterate(ObjectClosure* cl) {
323 GenerationObjIterateClosure blk(cl);
324 space_iterate(&blk);
325 }
326
327 class GenerationSafeObjIterateClosure : public SpaceClosure {
328 private:
329 ObjectClosure* _cl;
330 public:
331 virtual void do_space(Space* s) {
332 s->safe_object_iterate(_cl);
333 }
334 GenerationSafeObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
335 };
336
337 void Generation::safe_object_iterate(ObjectClosure* cl) {
338 GenerationSafeObjIterateClosure blk(cl);
339 space_iterate(&blk);
340 }
341
342 void Generation::prepare_for_compaction(CompactPoint* cp) {
343 // Generic implementation, can be specialized
344 CompactibleSpace* space = first_compaction_space();
345 while (space != NULL) {
346 space->prepare_for_compaction(cp);
347 space = space->next_compaction_space();
348 }
349 }
350
351 class AdjustPointersClosure: public SpaceClosure {
352 public:
353 void do_space(Space* sp) {
354 sp->adjust_pointers();
355 }
356 };
357
358 void Generation::adjust_pointers() {
359 // Note that this is done over all spaces, not just the compactible
360 // ones.
361 AdjustPointersClosure blk;
362 space_iterate(&blk, true);
363 }
364
365 void Generation::compact() {
366 CompactibleSpace* sp = first_compaction_space();
367 while (sp != NULL) {
368 sp->compact();
369 sp = sp->next_compaction_space();
370 }
371 }
372
373 CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size,
374 int level,
375 GenRemSet* remset) :
376 Generation(rs, initial_byte_size, level), _rs(remset),
377 _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(),
378 _used_at_prologue()
379 {
380 HeapWord* start = (HeapWord*)rs.base();
381 size_t reserved_byte_size = rs.size();
382 assert((uintptr_t(start) & 3) == 0, "bad alignment");
383 assert((reserved_byte_size & 3) == 0, "bad alignment");
384 MemRegion reserved_mr(start, heap_word_size(reserved_byte_size));
385 _bts = new BlockOffsetSharedArray(reserved_mr,
386 heap_word_size(initial_byte_size));
387 MemRegion committed_mr(start, heap_word_size(initial_byte_size));
388 _rs->resize_covered_region(committed_mr);
389 if (_bts == NULL)
390 vm_exit_during_initialization("Could not allocate a BlockOffsetArray");
391
392 // Verify that the start and end of this generation is the start of a card.
393 // If this wasn't true, a single card could span more than on generation,
394 // which would cause problems when we commit/uncommit memory, and when we
395 // clear and dirty cards.
396 guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned");
397 if (reserved_mr.end() != Universe::heap()->reserved_region().end()) {
398 // Don't check at the very end of the heap as we'll assert that we're probing off
399 // the end if we try.
400 guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned");
401 }
402 _min_heap_delta_bytes = MinHeapDeltaBytes;
403 _capacity_at_prologue = initial_byte_size;
404 _used_at_prologue = 0;
405 }
406
407 bool CardGeneration::expand(size_t bytes, size_t expand_bytes) {
408 assert_locked_or_safepoint(Heap_lock);
409 if (bytes == 0) {
410 return true; // That's what grow_by(0) would return
411 }
412 size_t aligned_bytes = ReservedSpace::page_align_size_up(bytes);
413 if (aligned_bytes == 0){
414 // The alignment caused the number of bytes to wrap. An expand_by(0) will
415 // return true with the implication that an expansion was done when it
416 // was not. A call to expand implies a best effort to expand by "bytes"
417 // but not a guarantee. Align down to give a best effort. This is likely
418 // the most that the generation can expand since it has some capacity to
419 // start with.
420 aligned_bytes = ReservedSpace::page_align_size_down(bytes);
421 }
422 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
423 bool success = false;
424 if (aligned_expand_bytes > aligned_bytes) {
425 success = grow_by(aligned_expand_bytes);
426 }
427 if (!success) {
428 success = grow_by(aligned_bytes);
429 }
430 if (!success) {
431 success = grow_to_reserved();
432 }
433 if (PrintGC && Verbose) {
434 if (success && GC_locker::is_active_and_needs_gc()) {
435 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");
436 }
437 }
438
439 return success;
440 }
441
442
443 // No young generation references, clear this generation's cards.
444 void CardGeneration::clear_remembered_set() {
445 _rs->clear(reserved());
446 }
447
448
449 // Objects in this generation may have moved, invalidate this
450 // generation's cards.
451 void CardGeneration::invalidate_remembered_set() {
452 _rs->invalidate(used_region());
453 }
454
455
456 void CardGeneration::compute_new_size() {
457 assert(_shrink_factor <= 100, "invalid shrink factor");
458 size_t current_shrink_factor = _shrink_factor;
459 _shrink_factor = 0;
460
461 // We don't have floating point command-line arguments
462 // Note: argument processing ensures that MinHeapFreeRatio < 100.
463 const double minimum_free_percentage = MinHeapFreeRatio / 100.0;
464 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
465
466 // Compute some numbers about the state of the heap.
467 const size_t used_after_gc = used();
468 const size_t capacity_after_gc = capacity();
469
470 const double min_tmp = used_after_gc / maximum_used_percentage;
471 size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx));
472 // Don't shrink less than the initial generation size
473 minimum_desired_capacity = MAX2(minimum_desired_capacity,
474 spec()->init_size());
475 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
476
477 if (PrintGC && Verbose) {
478 const size_t free_after_gc = free();
479 const double free_percentage = ((double)free_after_gc) / capacity_after_gc;
480 gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: ");
481 gclog_or_tty->print_cr(" "
482 " minimum_free_percentage: %6.2f"
483 " maximum_used_percentage: %6.2f",
484 minimum_free_percentage,
485 maximum_used_percentage);
486 gclog_or_tty->print_cr(" "
487 " free_after_gc : %6.1fK"
488 " used_after_gc : %6.1fK"
489 " capacity_after_gc : %6.1fK",
490 free_after_gc / (double) K,
491 used_after_gc / (double) K,
492 capacity_after_gc / (double) K);
493 gclog_or_tty->print_cr(" "
494 " free_percentage: %6.2f",
495 free_percentage);
496 }
497
498 if (capacity_after_gc < minimum_desired_capacity) {
499 // If we have less free space than we want then expand
500 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
501 // Don't expand unless it's significant
502 if (expand_bytes >= _min_heap_delta_bytes) {
503 expand(expand_bytes, 0); // safe if expansion fails
504 }
505 if (PrintGC && Verbose) {
506 gclog_or_tty->print_cr(" expanding:"
507 " minimum_desired_capacity: %6.1fK"
508 " expand_bytes: %6.1fK"
509 " _min_heap_delta_bytes: %6.1fK",
510 minimum_desired_capacity / (double) K,
511 expand_bytes / (double) K,
512 _min_heap_delta_bytes / (double) K);
513 }
514 return;
515 }
516
517 // No expansion, now see if we want to shrink
518 size_t shrink_bytes = 0;
519 // We would never want to shrink more than this
520 size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity;
521
522 if (MaxHeapFreeRatio < 100) {
523 const double maximum_free_percentage = MaxHeapFreeRatio / 100.0;
524 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
525 const double max_tmp = used_after_gc / minimum_used_percentage;
526 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx));
527 maximum_desired_capacity = MAX2(maximum_desired_capacity,
528 spec()->init_size());
529 if (PrintGC && Verbose) {
530 gclog_or_tty->print_cr(" "
531 " maximum_free_percentage: %6.2f"
532 " minimum_used_percentage: %6.2f",
533 maximum_free_percentage,
534 minimum_used_percentage);
535 gclog_or_tty->print_cr(" "
536 " _capacity_at_prologue: %6.1fK"
537 " minimum_desired_capacity: %6.1fK"
538 " maximum_desired_capacity: %6.1fK",
539 _capacity_at_prologue / (double) K,
540 minimum_desired_capacity / (double) K,
541 maximum_desired_capacity / (double) K);
542 }
543 assert(minimum_desired_capacity <= maximum_desired_capacity,
544 "sanity check");
545
546 if (capacity_after_gc > maximum_desired_capacity) {
547 // Capacity too large, compute shrinking size
548 shrink_bytes = capacity_after_gc - maximum_desired_capacity;
549 // We don't want shrink all the way back to initSize if people call
550 // System.gc(), because some programs do that between "phases" and then
551 // we'd just have to grow the heap up again for the next phase. So we
552 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
553 // on the third call, and 100% by the fourth call. But if we recompute
554 // size without shrinking, it goes back to 0%.
555 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
556 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
557 if (current_shrink_factor == 0) {
558 _shrink_factor = 10;
559 } else {
560 _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100);
561 }
562 if (PrintGC && Verbose) {
563 gclog_or_tty->print_cr(" "
564 " shrinking:"
565 " initSize: %.1fK"
566 " maximum_desired_capacity: %.1fK",
567 spec()->init_size() / (double) K,
568 maximum_desired_capacity / (double) K);
569 gclog_or_tty->print_cr(" "
570 " shrink_bytes: %.1fK"
571 " current_shrink_factor: " SIZE_FORMAT
572 " new shrink factor: " SIZE_FORMAT
573 " _min_heap_delta_bytes: %.1fK",
574 shrink_bytes / (double) K,
575 current_shrink_factor,
576 _shrink_factor,
577 _min_heap_delta_bytes / (double) K);
578 }
579 }
580 }
581
582 if (capacity_after_gc > _capacity_at_prologue) {
583 // We might have expanded for promotions, in which case we might want to
584 // take back that expansion if there's room after GC. That keeps us from
585 // stretching the heap with promotions when there's plenty of room.
586 size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue;
587 expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes);
588 // We have two shrinking computations, take the largest
589 shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion);
590 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
591 if (PrintGC && Verbose) {
592 gclog_or_tty->print_cr(" "
593 " aggressive shrinking:"
594 " _capacity_at_prologue: %.1fK"
595 " capacity_after_gc: %.1fK"
596 " expansion_for_promotion: %.1fK"
597 " shrink_bytes: %.1fK",
598 capacity_after_gc / (double) K,
599 _capacity_at_prologue / (double) K,
600 expansion_for_promotion / (double) K,
601 shrink_bytes / (double) K);
602 }
603 }
604 // Don't shrink unless it's significant
605 if (shrink_bytes >= _min_heap_delta_bytes) {
606 shrink(shrink_bytes);
607 }
608 }
609
610 // Currently nothing to do.
611 void CardGeneration::prepare_for_verify() {}
612
613
614 void OneContigSpaceCardGeneration::collect(bool full,
615 bool clear_all_soft_refs,
616 size_t size,
617 bool is_tlab) {
618 GenCollectedHeap* gch = GenCollectedHeap::heap();
619
620 SpecializationStats::clear();
621 // Temporarily expand the span of our ref processor, so
622 // refs discovery is over the entire heap, not just this generation
623 ReferenceProcessorSpanMutator
624 x(ref_processor(), gch->reserved_region());
625
626 STWGCTimer* gc_timer = GenMarkSweep::gc_timer();
627 gc_timer->register_gc_start();
628
629 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
630 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());
631
632 GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs);
633
634 gc_timer->register_gc_end();
635
636 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
637
638 SpecializationStats::print();
639 }
640
641 HeapWord*
642 OneContigSpaceCardGeneration::expand_and_allocate(size_t word_size,
643 bool is_tlab,
644 bool parallel) {
645 assert(!is_tlab, "OneContigSpaceCardGeneration does not support TLAB allocation");
646 if (parallel) {
647 MutexLocker x(ParGCRareEvent_lock);
648 HeapWord* result = NULL;
649 size_t byte_size = word_size * HeapWordSize;
650 while (true) {
651 expand(byte_size, _min_heap_delta_bytes);
652 if (GCExpandToAllocateDelayMillis > 0) {
653 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false);
654 }
655 result = _the_space->par_allocate(word_size);
656 if ( result != NULL) {
657 return result;
658 } else {
659 // If there's not enough expansion space available, give up.
660 if (_virtual_space.uncommitted_size() < byte_size) {
661 return NULL;
662 }
663 // else try again
664 }
665 }
666 } else {
667 expand(word_size*HeapWordSize, _min_heap_delta_bytes);
668 return _the_space->allocate(word_size);
669 }
670 }
671
672 bool OneContigSpaceCardGeneration::expand(size_t bytes, size_t expand_bytes) {
673 GCMutexLocker x(ExpandHeap_lock);
674 return CardGeneration::expand(bytes, expand_bytes);
675 }
676
677
678 void OneContigSpaceCardGeneration::shrink(size_t bytes) {
679 assert_locked_or_safepoint(ExpandHeap_lock);
680 size_t size = ReservedSpace::page_align_size_down(bytes);
681 if (size > 0) {
682 shrink_by(size);
683 }
684 }
685
686
687 size_t OneContigSpaceCardGeneration::capacity() const {
688 return _the_space->capacity();
689 }
690
691
692 size_t OneContigSpaceCardGeneration::used() const {
693 return _the_space->used();
694 }
695
696
697 size_t OneContigSpaceCardGeneration::free() const {
698 return _the_space->free();
699 }
700
701 MemRegion OneContigSpaceCardGeneration::used_region() const {
702 return the_space()->used_region();
703 }
704
705 size_t OneContigSpaceCardGeneration::unsafe_max_alloc_nogc() const {
706 return _the_space->free();
707 }
708
709 size_t OneContigSpaceCardGeneration::contiguous_available() const {
710 return _the_space->free() + _virtual_space.uncommitted_size();
711 }
712
713 bool OneContigSpaceCardGeneration::grow_by(size_t bytes) {
714 assert_locked_or_safepoint(ExpandHeap_lock);
715 bool result = _virtual_space.expand_by(bytes);
716 if (result) {
717 size_t new_word_size =
718 heap_word_size(_virtual_space.committed_size());
719 MemRegion mr(_the_space->bottom(), new_word_size);
720 // Expand card table
721 Universe::heap()->barrier_set()->resize_covered_region(mr);
722 // Expand shared block offset array
723 _bts->resize(new_word_size);
724
725 // Fix for bug #4668531
726 if (ZapUnusedHeapArea) {
727 MemRegion mangle_region(_the_space->end(),
728 (HeapWord*)_virtual_space.high());
729 SpaceMangler::mangle_region(mangle_region);
730 }
731
732 // Expand space -- also expands space's BOT
733 // (which uses (part of) shared array above)
734 _the_space->set_end((HeapWord*)_virtual_space.high());
735
736 // update the space and generation capacity counters
737 update_counters();
738
739 if (Verbose && PrintGC) {
740 size_t new_mem_size = _virtual_space.committed_size();
741 size_t old_mem_size = new_mem_size - bytes;
742 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by "
743 SIZE_FORMAT "K to " SIZE_FORMAT "K",
744 name(), old_mem_size/K, bytes/K, new_mem_size/K);
745 }
746 }
747 return result;
748 }
749
750
751 bool OneContigSpaceCardGeneration::grow_to_reserved() {
752 assert_locked_or_safepoint(ExpandHeap_lock);
753 bool success = true;
754 const size_t remaining_bytes = _virtual_space.uncommitted_size();
755 if (remaining_bytes > 0) {
756 success = grow_by(remaining_bytes);
757 DEBUG_ONLY(if (!success) warning("grow to reserved failed");)
758 }
759 return success;
760 }
761
762 void OneContigSpaceCardGeneration::shrink_by(size_t bytes) {
763 assert_locked_or_safepoint(ExpandHeap_lock);
764 // Shrink committed space
765 _virtual_space.shrink_by(bytes);
766 // Shrink space; this also shrinks the space's BOT
767 _the_space->set_end((HeapWord*) _virtual_space.high());
768 size_t new_word_size = heap_word_size(_the_space->capacity());
769 // Shrink the shared block offset array
770 _bts->resize(new_word_size);
771 MemRegion mr(_the_space->bottom(), new_word_size);
772 // Shrink the card table
773 Universe::heap()->barrier_set()->resize_covered_region(mr);
774
775 if (Verbose && PrintGC) {
776 size_t new_mem_size = _virtual_space.committed_size();
777 size_t old_mem_size = new_mem_size + bytes;
778 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
779 name(), old_mem_size/K, new_mem_size/K);
780 }
781 }
782
783 // Currently nothing to do.
784 void OneContigSpaceCardGeneration::prepare_for_verify() {}
785
786
787 // Override for a card-table generation with one contiguous
788 // space. NOTE: For reasons that are lost in the fog of history,
789 // this code is used when you iterate over perm gen objects,
790 // even when one uses CDS, where the perm gen has a couple of
791 // other spaces; this is because CompactingPermGenGen derives
792 // from OneContigSpaceCardGeneration. This should be cleaned up,
793 // see CR 6897789..
794 void OneContigSpaceCardGeneration::object_iterate(ObjectClosure* blk) {
795 _the_space->object_iterate(blk);
796 }
797
798 void OneContigSpaceCardGeneration::space_iterate(SpaceClosure* blk,
799 bool usedOnly) {
800 blk->do_space(_the_space);
801 }
802
803 void OneContigSpaceCardGeneration::younger_refs_iterate(OopsInGenClosure* blk) {
804 blk->set_generation(this);
805 younger_refs_in_space_iterate(_the_space, blk);
806 blk->reset_generation();
807 }
808
809 void OneContigSpaceCardGeneration::save_marks() {
810 _the_space->set_saved_mark();
811 }
812
813
814 void OneContigSpaceCardGeneration::reset_saved_marks() {
815 _the_space->reset_saved_mark();
816 }
817
818
819 bool OneContigSpaceCardGeneration::no_allocs_since_save_marks() {
820 return _the_space->saved_mark_at_top();
821 }
822
823 #define OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
824 \
825 void OneContigSpaceCardGeneration:: \
826 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
827 blk->set_generation(this); \
828 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \
829 blk->reset_generation(); \
830 save_marks(); \
831 }
832
833 ALL_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN)
834
835 #undef OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN
836
837
838 void OneContigSpaceCardGeneration::gc_epilogue(bool full) {
839 _last_gc = WaterMark(the_space(), the_space()->top());
840
841 // update the generation and space performance counters
842 update_counters();
843 if (ZapUnusedHeapArea) {
844 the_space()->check_mangled_unused_area_complete();
845 }
846 }
847
848 void OneContigSpaceCardGeneration::record_spaces_top() {
849 assert(ZapUnusedHeapArea, "Not mangling unused space");
850 the_space()->set_top_for_allocations();
851 }
852
853 void OneContigSpaceCardGeneration::verify() {
854 the_space()->verify();
855 }
856
857 void OneContigSpaceCardGeneration::print_on(outputStream* st) const {
858 Generation::print_on(st);
859 st->print(" the");
860 the_space()->print_on(st);
861 }