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