1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)defNewGeneration.cpp 1.73 07/05/22 17:24:57 JVM"
3 #endif
4 /*
5 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 # include "incls/_precompiled.incl"
29 # include "incls/_defNewGeneration.cpp.incl"
30
31 //
32 // DefNewGeneration functions.
33
34 // Methods of protected closure types.
35
36 DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) {
37 assert(g->level() == 0, "Optimized for youngest gen.");
38 }
39 void DefNewGeneration::IsAliveClosure::do_object(oop p) {
40 assert(false, "Do not call.");
41 }
42 bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
43 return (HeapWord*)p >= _g->reserved().end() || p->is_forwarded();
44 }
45
46 DefNewGeneration::KeepAliveClosure::
47 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
48 GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
49 assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind.");
50 _rs = (CardTableRS*)rs;
51 }
52
53 void DefNewGeneration::KeepAliveClosure::do_oop(oop* p) {
54 // We never expect to see a null reference being processed
55 // as a weak reference.
56 assert (*p != NULL, "expected non-null ref");
57 assert ((*p)->is_oop(), "expected an oop while scanning weak refs");
58
59 _cl->do_oop_nv(p);
60
61 // Card marking is trickier for weak refs.
62 // This oop is a 'next' field which was filled in while we
63 // were discovering weak references. While we might not need
64 // to take a special action to keep this reference alive, we
65 // will need to dirty a card as the field was modified.
66 //
67 // Alternatively, we could create a method which iterates through
68 // each generation, allowing them in turn to examine the modified
69 // field.
70 //
71 // We could check that p is also in an older generation, but
72 // dirty cards in the youngest gen are never scanned, so the
73 // extra check probably isn't worthwhile.
74 if (Universe::heap()->is_in_reserved(p)) {
75 _rs->inline_write_ref_field_gc(p, *p);
76 }
77 }
78
79 DefNewGeneration::FastKeepAliveClosure::
80 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
81 DefNewGeneration::KeepAliveClosure(cl) {
82 _boundary = g->reserved().end();
83 }
84
85 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p) {
86 assert (*p != NULL, "expected non-null ref");
87 assert ((*p)->is_oop(), "expected an oop while scanning weak refs");
88
89 _cl->do_oop_nv(p);
90
91 // Optimized for Defnew generation if it's the youngest generation:
92 // we set a younger_gen card if we have an older->youngest
93 // generation pointer.
94 if (((HeapWord*)(*p) < _boundary) && Universe::heap()->is_in_reserved(p)) {
95 _rs->inline_write_ref_field_gc(p, *p);
96 }
97 }
98
99 DefNewGeneration::EvacuateFollowersClosure::
100 EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
101 ScanClosure* cur, ScanClosure* older) :
102 _gch(gch), _level(level),
103 _scan_cur_or_nonheap(cur), _scan_older(older)
104 {}
105
106 void DefNewGeneration::EvacuateFollowersClosure::do_void() {
107 do {
108 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
109 _scan_older);
110 } while (!_gch->no_allocs_since_save_marks(_level));
111 }
112
113 DefNewGeneration::FastEvacuateFollowersClosure::
114 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
115 DefNewGeneration* gen,
116 FastScanClosure* cur, FastScanClosure* older) :
117 _gch(gch), _level(level), _gen(gen),
118 _scan_cur_or_nonheap(cur), _scan_older(older)
119 {}
120
121 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() {
122 do {
123 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
124 _scan_older);
125 } while (!_gch->no_allocs_since_save_marks(_level));
126 guarantee(_gen->promo_failure_scan_stack() == NULL
127 || _gen->promo_failure_scan_stack()->length() == 0,
128 "Failed to finish scan");
129 }
130
131 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) :
132 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
133 {
134 assert(_g->level() == 0, "Optimized for youngest generation");
135 _boundary = _g->reserved().end();
136 }
137
138 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) :
139 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
140 {
141 assert(_g->level() == 0, "Optimized for youngest generation");
142 _boundary = _g->reserved().end();
143 }
144
145 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) :
146 OopClosure(g->ref_processor()), _g(g)
147 {
148 assert(_g->level() == 0, "Optimized for youngest generation");
149 _boundary = _g->reserved().end();
150 }
151
152
153 DefNewGeneration::DefNewGeneration(ReservedSpace rs,
154 size_t initial_size,
155 int level,
156 const char* policy)
157 : Generation(rs, initial_size, level),
158 _objs_with_preserved_marks(NULL),
159 _preserved_marks_of_objs(NULL),
160 _promo_failure_scan_stack(NULL),
161 _promo_failure_drain_in_progress(false),
162 _should_allocate_from_space(false)
163 {
164 MemRegion cmr((HeapWord*)_virtual_space.low(),
165 (HeapWord*)_virtual_space.high());
166 Universe::heap()->barrier_set()->resize_covered_region(cmr);
167
168 if (GenCollectedHeap::heap()->collector_policy()->has_soft_ended_eden()) {
169 _eden_space = new ConcEdenSpace(this);
170 } else {
171 _eden_space = new EdenSpace(this);
172 }
173 _from_space = new ContiguousSpace();
174 _to_space = new ContiguousSpace();
175
176 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL)
177 vm_exit_during_initialization("Could not allocate a new gen space");
178
179 // Compute the maximum eden and survivor space sizes. These sizes
180 // are computed assuming the entire reserved space is committed.
181 // These values are exported as performance counters.
182 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
183 uintx size = _virtual_space.reserved_size();
184 _max_survivor_size = compute_survivor_size(size, alignment);
185 _max_eden_size = size - (2*_max_survivor_size);
186
187 // allocate the performance counters
188
189 // Generation counters -- generation 0, 3 subspaces
190 _gen_counters = new GenerationCounters("new", 0, 3, &_virtual_space);
191 _gc_counters = new CollectorCounters(policy, 0);
192
193 _eden_counters = new CSpaceCounters("eden", 0, _max_eden_size, _eden_space,
194 _gen_counters);
195 _from_counters = new CSpaceCounters("s0", 1, _max_survivor_size, _from_space,
196 _gen_counters);
197 _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space,
198 _gen_counters);
199
200 compute_space_boundaries(0);
201 update_counters();
202 _next_gen = NULL;
203 _tenuring_threshold = MaxTenuringThreshold;
204 _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize;
205 }
206
207 void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size) {
208 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
209
210 // Compute sizes
211 uintx size = _virtual_space.committed_size();
212 uintx survivor_size = compute_survivor_size(size, alignment);
213 uintx eden_size = size - (2*survivor_size);
214 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
215
216 if (eden_size < minimum_eden_size) {
217 // May happen due to 64Kb rounding, if so adjust eden size back up
218 minimum_eden_size = align_size_up(minimum_eden_size, alignment);
219 uintx maximum_survivor_size = (size - minimum_eden_size) / 2;
220 uintx unaligned_survivor_size =
221 align_size_down(maximum_survivor_size, alignment);
222 survivor_size = MAX2(unaligned_survivor_size, alignment);
223 eden_size = size - (2*survivor_size);
224 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
225 assert(eden_size >= minimum_eden_size, "just checking");
226 }
227
228 char *eden_start = _virtual_space.low();
229 char *from_start = eden_start + eden_size;
230 char *to_start = from_start + survivor_size;
231 char *to_end = to_start + survivor_size;
232
233 assert(to_end == _virtual_space.high(), "just checking");
234 assert(Space::is_aligned((HeapWord*)eden_start), "checking alignment");
235 assert(Space::is_aligned((HeapWord*)from_start), "checking alignment");
236 assert(Space::is_aligned((HeapWord*)to_start), "checking alignment");
237
238 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)from_start);
239 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start);
240 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
241
242 eden()->initialize(edenMR, (minimum_eden_size == 0));
243 // If minumum_eden_size != 0, we will not have cleared any
244 // portion of eden above its top. This can cause newly
245 // expanded space not to be mangled if using ZapUnusedHeapArea.
246 // We explicitly do such mangling here.
247 if (ZapUnusedHeapArea && (minimum_eden_size != 0)) {
248 eden()->mangle_unused_area();
249 }
250 from()->initialize(fromMR, true);
251 to()->initialize(toMR , true);
252 eden()->set_next_compaction_space(from());
253 // The to-space is normally empty before a compaction so need
254 // not be considered. The exception is during promotion
255 // failure handling when to-space can contain live objects.
256 from()->set_next_compaction_space(NULL);
257 }
258
259 void DefNewGeneration::swap_spaces() {
260 ContiguousSpace* s = from();
261 _from_space = to();
262 _to_space = s;
263 eden()->set_next_compaction_space(from());
264 // The to-space is normally empty before a compaction so need
265 // not be considered. The exception is during promotion
266 // failure handling when to-space can contain live objects.
267 from()->set_next_compaction_space(NULL);
268
269 if (UsePerfData) {
270 CSpaceCounters* c = _from_counters;
271 _from_counters = _to_counters;
272 _to_counters = c;
273 }
274 }
275
276 bool DefNewGeneration::expand(size_t bytes) {
277 MutexLocker x(ExpandHeap_lock);
278 bool success = _virtual_space.expand_by(bytes);
279
280 // Do not attempt an expand-to-the reserve size. The
281 // request should properly observe the maximum size of
282 // the generation so an expand-to-reserve should be
283 // unnecessary. Also a second call to expand-to-reserve
284 // value potentially can cause an undue expansion.
285 // For example if the first expand fail for unknown reasons,
286 // but the second succeeds and expands the heap to its maximum
287 // value.
288 if (GC_locker::is_active()) {
289 if (PrintGC && Verbose) {
290 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");
291 }
292 }
293
294 return success;
295 }
296
297
298 void DefNewGeneration::compute_new_size() {
299 // This is called after a gc that includes the following generation
300 // (which is required to exist.) So from-space will normally be empty.
301 // Note that we check both spaces, since if scavenge failed they revert roles.
302 // If not we bail out (otherwise we would have to relocate the objects)
303 if (!from()->is_empty() || !to()->is_empty()) {
304 return;
305 }
306
307 int next_level = level() + 1;
308 GenCollectedHeap* gch = GenCollectedHeap::heap();
309 assert(next_level < gch->_n_gens,
310 "DefNewGeneration cannot be an oldest gen");
311
312 Generation* next_gen = gch->_gens[next_level];
313 size_t old_size = next_gen->capacity();
314 size_t new_size_before = _virtual_space.committed_size();
315 size_t min_new_size = spec()->init_size();
316 size_t max_new_size = reserved().byte_size();
317 assert(min_new_size <= new_size_before &&
318 new_size_before <= max_new_size,
319 "just checking");
320 // All space sizes must be multiples of Generation::GenGrain.
321 size_t alignment = Generation::GenGrain;
322
323 // Compute desired new generation size based on NewRatio and
324 // NewSizeThreadIncrease
325 size_t desired_new_size = old_size/NewRatio;
326 int threads_count = Threads::number_of_non_daemon_threads();
327 size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
328 desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
329
330 // Adjust new generation size
331 desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);
332 assert(desired_new_size <= max_new_size, "just checking");
333
334 bool changed = false;
335 if (desired_new_size > new_size_before) {
336 size_t change = desired_new_size - new_size_before;
337 assert(change % alignment == 0, "just checking");
338 if (expand(change)) {
339 changed = true;
340 }
341 // If the heap failed to expand to the desired size,
342 // "changed" will be false. If the expansion failed
343 // (and at this point it was expected to succeed),
344 // ignore the failure (leaving "changed" as false).
345 }
346 if (desired_new_size < new_size_before && eden()->is_empty()) {
347 // bail out of shrinking if objects in eden
348 size_t change = new_size_before - desired_new_size;
349 assert(change % alignment == 0, "just checking");
350 _virtual_space.shrink_by(change);
351 changed = true;
352 }
353 if (changed) {
354 compute_space_boundaries(eden()->used());
355 MemRegion cmr((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
356 Universe::heap()->barrier_set()->resize_covered_region(cmr);
357 if (Verbose && PrintGC) {
358 size_t new_size_after = _virtual_space.committed_size();
359 size_t eden_size_after = eden()->capacity();
360 size_t survivor_size_after = from()->capacity();
361 gclog_or_tty->print("New generation size " SIZE_FORMAT "K->" SIZE_FORMAT "K [eden="
362 SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]",
363 new_size_before/K, new_size_after/K, eden_size_after/K, survivor_size_after/K);
364 if (WizardMode) {
365 gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]",
366 thread_increase_size/K, threads_count);
367 }
368 gclog_or_tty->cr();
369 }
370 }
371 }
372
373 void DefNewGeneration::object_iterate_since_last_GC(ObjectClosure* cl) {
374 // $$$ This may be wrong in case of "scavenge failure"?
375 eden()->object_iterate(cl);
376 }
377
378 void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl) {
379 assert(false, "NYI -- are you sure you want to call this?");
380 }
381
382
383 size_t DefNewGeneration::capacity() const {
384 return eden()->capacity()
385 + from()->capacity(); // to() is only used during scavenge
386 }
387
388
389 size_t DefNewGeneration::used() const {
390 return eden()->used()
391 + from()->used(); // to() is only used during scavenge
392 }
393
394
395 size_t DefNewGeneration::free() const {
396 return eden()->free()
397 + from()->free(); // to() is only used during scavenge
398 }
399
400 size_t DefNewGeneration::max_capacity() const {
401 const size_t alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
402 const size_t reserved_bytes = reserved().byte_size();
403 return reserved_bytes - compute_survivor_size(reserved_bytes, alignment);
404 }
405
406 size_t DefNewGeneration::unsafe_max_alloc_nogc() const {
407 return eden()->free();
408 }
409
410 size_t DefNewGeneration::capacity_before_gc() const {
411 return eden()->capacity();
412 }
413
414 size_t DefNewGeneration::contiguous_available() const {
415 return eden()->free();
416 }
417
418
419 HeapWord** DefNewGeneration::top_addr() const { return eden()->top_addr(); }
420 HeapWord** DefNewGeneration::end_addr() const { return eden()->end_addr(); }
421
422 void DefNewGeneration::object_iterate(ObjectClosure* blk) {
423 eden()->object_iterate(blk);
424 from()->object_iterate(blk);
425 }
426
427
428 void DefNewGeneration::space_iterate(SpaceClosure* blk,
429 bool usedOnly) {
430 blk->do_space(eden());
431 blk->do_space(from());
432 blk->do_space(to());
433 }
434
435 // The last collection bailed out, we are running out of heap space,
436 // so we try to allocate the from-space, too.
437 HeapWord* DefNewGeneration::allocate_from_space(size_t size) {
438 HeapWord* result = NULL;
439 if (PrintGC && Verbose) {
440 gclog_or_tty->print("DefNewGeneration::allocate_from_space(%u):"
441 " will_fail: %s"
442 " heap_lock: %s"
443 " free: " SIZE_FORMAT,
444 size,
445 GenCollectedHeap::heap()->incremental_collection_will_fail() ? "true" : "false",
446 Heap_lock->is_locked() ? "locked" : "unlocked",
447 from()->free());
448 }
449 if (should_allocate_from_space() || GC_locker::is_active_and_needs_gc()) {
450 if (Heap_lock->owned_by_self() ||
451 (SafepointSynchronize::is_at_safepoint() &&
452 Thread::current()->is_VM_thread())) {
453 // If the Heap_lock is not locked by this thread, this will be called
454 // again later with the Heap_lock held.
455 result = from()->allocate(size);
456 } else if (PrintGC && Verbose) {
457 gclog_or_tty->print_cr(" Heap_lock is not owned by self");
458 }
459 } else if (PrintGC && Verbose) {
460 gclog_or_tty->print_cr(" should_allocate_from_space: NOT");
461 }
462 if (PrintGC && Verbose) {
463 gclog_or_tty->print_cr(" returns %s", result == NULL ? "NULL" : "object");
464 }
465 return result;
466 }
467
468 HeapWord* DefNewGeneration::expand_and_allocate(size_t size,
469 bool is_tlab,
470 bool parallel) {
471 // We don't attempt to expand the young generation (but perhaps we should.)
472 return allocate(size, is_tlab);
473 }
474
475
476 void DefNewGeneration::collect(bool full,
477 bool clear_all_soft_refs,
478 size_t size,
479 bool is_tlab) {
480 assert(full || size > 0, "otherwise we don't want to collect");
481 GenCollectedHeap* gch = GenCollectedHeap::heap();
482 _next_gen = gch->next_gen(this);
483 assert(_next_gen != NULL,
484 "This must be the youngest gen, and not the only gen");
485
486 // If the next generation is too full to accomodate promotion
487 // from this generation, pass on collection; let the next generation
488 // do it.
489 if (!collection_attempt_is_safe()) {
490 gch->set_incremental_collection_will_fail();
491 return;
492 }
493 assert(to()->is_empty(), "Else not collection_attempt_is_safe");
494
495 init_assuming_no_promotion_failure();
496
497 TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
498 // Capture heap used before collection (for printing).
499 size_t gch_prev_used = gch->used();
500
501 SpecializationStats::clear();
502
503 // These can be shared for all code paths
504 IsAliveClosure is_alive(this);
505 ScanWeakRefClosure scan_weak_ref(this);
506
507 age_table()->clear();
508 to()->clear();
509
510 gch->rem_set()->prepare_for_younger_refs_iterate(false);
511
512 assert(gch->no_allocs_since_save_marks(0),
513 "save marks have not been newly set.");
514
515 // Weak refs.
516 // FIXME: Are these storage leaks, or are they resource objects?
517 #ifdef COMPILER2
518 ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy();
519 #else
520 ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy();
521 #endif // COMPILER2
522
523 // Not very pretty.
524 CollectorPolicy* cp = gch->collector_policy();
525
526 FastScanClosure fsc_with_no_gc_barrier(this, false);
527 FastScanClosure fsc_with_gc_barrier(this, true);
528
529 set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
530 FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
531 &fsc_with_no_gc_barrier,
532 &fsc_with_gc_barrier);
533
534 assert(gch->no_allocs_since_save_marks(0),
535 "save marks have not been newly set.");
536
537 gch->gen_process_strong_roots(_level,
538 true, // Process younger gens, if any, as
539 // strong roots.
540 false,// not collecting permanent generation.
541 SharedHeap::SO_AllClasses,
542 &fsc_with_gc_barrier,
543 &fsc_with_no_gc_barrier);
544
545 // "evacuate followers".
546 evacuate_followers.do_void();
547
548 FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
549 ref_processor()->process_discovered_references(
550 soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, NULL);
551 if (!promotion_failed()) {
552 // Swap the survivor spaces.
553 eden()->clear();
554 from()->clear();
555 swap_spaces();
556
557 assert(to()->is_empty(), "to space should be empty now");
558
559 // Set the desired survivor size to half the real survivor space
560 _tenuring_threshold =
561 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize);
562
563 if (PrintGC && !PrintGCDetails) {
564 gch->print_heap_change(gch_prev_used);
565 }
566 } else {
567 assert(HandlePromotionFailure,
568 "Should not be here unless promotion failure handling is on");
569 assert(_promo_failure_scan_stack != NULL &&
570 _promo_failure_scan_stack->length() == 0, "post condition");
571
572 // deallocate stack and it's elements
573 delete _promo_failure_scan_stack;
574 _promo_failure_scan_stack = NULL;
575
576 remove_forwarding_pointers();
577 if (PrintGCDetails) {
578 gclog_or_tty->print(" (promotion failed)");
579 }
580 // Add to-space to the list of space to compact
581 // when a promotion failure has occurred. In that
582 // case there can be live objects in to-space
583 // as a result of a partial evacuation of eden
584 // and from-space.
585 swap_spaces(); // For the sake of uniformity wrt ParNewGeneration::collect().
586 from()->set_next_compaction_space(to());
587 gch->set_incremental_collection_will_fail();
588
589 // Reset the PromotionFailureALot counters.
590 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
591 }
592 // set new iteration safe limit for the survivor spaces
593 from()->set_concurrent_iteration_safe_limit(from()->top());
594 to()->set_concurrent_iteration_safe_limit(to()->top());
595 SpecializationStats::print();
596 update_time_of_last_gc(os::javaTimeMillis());
597 }
598
599 class RemoveForwardPointerClosure: public ObjectClosure {
600 public:
601 void do_object(oop obj) {
602 obj->init_mark();
603 }
604 };
605
606 void DefNewGeneration::init_assuming_no_promotion_failure() {
607 _promotion_failed = false;
608 from()->set_next_compaction_space(NULL);
609 }
610
611 void DefNewGeneration::remove_forwarding_pointers() {
612 RemoveForwardPointerClosure rspc;
613 eden()->object_iterate(&rspc);
614 from()->object_iterate(&rspc);
615 // Now restore saved marks, if any.
616 if (_objs_with_preserved_marks != NULL) {
617 assert(_preserved_marks_of_objs != NULL, "Both or none.");
618 assert(_objs_with_preserved_marks->length() ==
619 _preserved_marks_of_objs->length(), "Both or none.");
620 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
621 oop obj = _objs_with_preserved_marks->at(i);
622 markOop m = _preserved_marks_of_objs->at(i);
623 obj->set_mark(m);
624 }
625 delete _objs_with_preserved_marks;
626 delete _preserved_marks_of_objs;
627 _objs_with_preserved_marks = NULL;
628 _preserved_marks_of_objs = NULL;
629 }
630 }
631
632 void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) {
633 if (m->must_be_preserved_for_promotion_failure(obj)) {
634 if (_objs_with_preserved_marks == NULL) {
635 assert(_preserved_marks_of_objs == NULL, "Both or none.");
636 _objs_with_preserved_marks = new (ResourceObj::C_HEAP)
637 GrowableArray<oop>(PreserveMarkStackSize, true);
638 _preserved_marks_of_objs = new (ResourceObj::C_HEAP)
639 GrowableArray<markOop>(PreserveMarkStackSize, true);
640 }
641 _objs_with_preserved_marks->push(obj);
642 _preserved_marks_of_objs->push(m);
643 }
644 }
645
646 void DefNewGeneration::handle_promotion_failure(oop old) {
647 preserve_mark_if_necessary(old, old->mark());
648 // forward to self
649 old->forward_to(old);
650 _promotion_failed = true;
651
652 push_on_promo_failure_scan_stack(old);
653
654 if (!_promo_failure_drain_in_progress) {
655 // prevent recursion in copy_to_survivor_space()
656 _promo_failure_drain_in_progress = true;
657 drain_promo_failure_scan_stack();
658 _promo_failure_drain_in_progress = false;
659 }
660 }
661
662 oop DefNewGeneration::copy_to_survivor_space(oop old, oop* from) {
663 assert(is_in_reserved(old) && !old->is_forwarded(),
664 "shouldn't be scavenging this oop");
665 size_t s = old->size();
666 oop obj = NULL;
667
668 // Try allocating obj in to-space (unless too old)
669 if (old->age() < tenuring_threshold()) {
670 obj = (oop) to()->allocate(s);
671 }
672
673 // Otherwise try allocating obj tenured
674 if (obj == NULL) {
675 obj = _next_gen->promote(old, s, from);
676 if (obj == NULL) {
677 if (!HandlePromotionFailure) {
678 // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag
679 // is incorrectly set. In any case, its seriously wrong to be here!
680 vm_exit_out_of_memory(s*wordSize, "promotion");
681 }
682
683 handle_promotion_failure(old);
684 return old;
685 }
686 } else {
687 // Prefetch beyond obj
688 const intx interval = PrefetchCopyIntervalInBytes;
689 Prefetch::write(obj, interval);
690
691 // Copy obj
692 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)obj, s);
693
694 // Increment age if obj still in new generation
695 obj->incr_age();
696 age_table()->add(obj, s);
697 }
698
699 // Done, insert forward pointer to obj in this header
700 old->forward_to(obj);
701
702 return obj;
703 }
704
705 void DefNewGeneration::push_on_promo_failure_scan_stack(oop obj) {
706 if (_promo_failure_scan_stack == NULL) {
707 _promo_failure_scan_stack = new (ResourceObj::C_HEAP)
708 GrowableArray<oop>(40, true);
709 }
710
711 _promo_failure_scan_stack->push(obj);
712 }
713
714 void DefNewGeneration::drain_promo_failure_scan_stack() {
715 assert(_promo_failure_scan_stack != NULL, "precondition");
716
717 while (_promo_failure_scan_stack->length() > 0) {
718 oop obj = _promo_failure_scan_stack->pop();
719 obj->oop_iterate(_promo_failure_scan_stack_closure);
720 }
721 }
722
723 void DefNewGeneration::save_marks() {
724 eden()->set_saved_mark();
725 to()->set_saved_mark();
726 from()->set_saved_mark();
727 }
728
729
730 void DefNewGeneration::reset_saved_marks() {
731 eden()->reset_saved_mark();
732 to()->reset_saved_mark();
733 from()->reset_saved_mark();
734 }
735
736
737 bool DefNewGeneration::no_allocs_since_save_marks() {
738 assert(eden()->saved_mark_at_top(), "Violated spec - alloc in eden");
739 assert(from()->saved_mark_at_top(), "Violated spec - alloc in from");
740 return to()->saved_mark_at_top();
741 }
742
743 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
744 \
745 void DefNewGeneration:: \
746 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
747 cl->set_generation(this); \
748 eden()->oop_since_save_marks_iterate##nv_suffix(cl); \
749 to()->oop_since_save_marks_iterate##nv_suffix(cl); \
750 from()->oop_since_save_marks_iterate##nv_suffix(cl); \
751 cl->reset_generation(); \
752 save_marks(); \
753 }
754
755 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN)
756
757 #undef DefNew_SINCE_SAVE_MARKS_DEFN
758
759 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor,
760 size_t max_alloc_words) {
761 if (requestor == this || _promotion_failed) return;
762 assert(requestor->level() > level(), "DefNewGeneration must be youngest");
763
764 /* $$$ Assert this? "trace" is a "MarkSweep" function so that's not appropriate.
765 if (to_space->top() > to_space->bottom()) {
766 trace("to_space not empty when contribute_scratch called");
767 }
768 */
769
770 ContiguousSpace* to_space = to();
771 assert(to_space->end() >= to_space->top(), "pointers out of order");
772 size_t free_words = pointer_delta(to_space->end(), to_space->top());
773 if (free_words >= MinFreeScratchWords) {
774 ScratchBlock* sb = (ScratchBlock*)to_space->top();
775 sb->num_words = free_words;
776 sb->next = list;
777 list = sb;
778 }
779 }
780
781 bool DefNewGeneration::collection_attempt_is_safe() {
782 if (!to()->is_empty()) {
783 return false;
784 }
785 if (_next_gen == NULL) {
786 GenCollectedHeap* gch = GenCollectedHeap::heap();
787 _next_gen = gch->next_gen(this);
788 assert(_next_gen != NULL,
789 "This must be the youngest gen, and not the only gen");
790 }
791
792 // Decide if there's enough room for a full promotion
793 // When using extremely large edens, we effectively lose a
794 // large amount of old space. Use the "MaxLiveObjectEvacuationRatio"
795 // flag to reduce the minimum evacuation space requirements. If
796 // there is not enough space to evacuate eden during a scavenge,
797 // the VM will immediately exit with an out of memory error.
798 // This flag has not been tested
799 // with collectors other than simple mark & sweep.
800 //
801 // Note that with the addition of promotion failure handling, the
802 // VM will not immediately exit but will undo the young generation
803 // collection. The parameter is left here for compatibility.
804 const double evacuation_ratio = MaxLiveObjectEvacuationRatio / 100.0;
805
806 // worst_case_evacuation is based on "used()". For the case where this
807 // method is called after a collection, this is still appropriate because
808 // the case that needs to be detected is one in which a full collection
809 // has been done and has overflowed into the young generation. In that
810 // case a minor collection will fail (the overflow of the full collection
811 // means there is no space in the old generation for any promotion).
812 size_t worst_case_evacuation = (size_t)(used() * evacuation_ratio);
813
814 return _next_gen->promotion_attempt_is_safe(worst_case_evacuation,
815 HandlePromotionFailure);
816 }
817
818 void DefNewGeneration::gc_epilogue(bool full) {
819 // Check if the heap is approaching full after a collection has
820 // been done. Generally the young generation is empty at
821 // a minimum at the end of a collection. If it is not, then
822 // the heap is approaching full.
823 GenCollectedHeap* gch = GenCollectedHeap::heap();
824 clear_should_allocate_from_space();
825 if (collection_attempt_is_safe()) {
826 gch->clear_incremental_collection_will_fail();
827 } else {
828 gch->set_incremental_collection_will_fail();
829 if (full) { // we seem to be running out of space
830 set_should_allocate_from_space();
831 }
832 }
833
834 // update the generation and space performance counters
835 update_counters();
836 gch->collector_policy()->counters()->update_counters();
837 }
838
839 void DefNewGeneration::update_counters() {
840 if (UsePerfData) {
841 _eden_counters->update_all();
842 _from_counters->update_all();
843 _to_counters->update_all();
844 _gen_counters->update_all();
845 }
846 }
847
848 void DefNewGeneration::verify(bool allow_dirty) {
849 eden()->verify(allow_dirty);
850 from()->verify(allow_dirty);
851 to()->verify(allow_dirty);
852 }
853
854 void DefNewGeneration::print_on(outputStream* st) const {
855 Generation::print_on(st);
856 st->print(" eden");
857 eden()->print_on(st);
858 st->print(" from");
859 from()->print_on(st);
860 st->print(" to ");
861 to()->print_on(st);
862 }
863
864
865 const char* DefNewGeneration::name() const {
866 return "def new generation";
867 }