Wed, 02 Jul 2008 12:55:16 -0700
6719955: Update copyright year
Summary: Update copyright year for files that have been modified in 2008
Reviewed-by: ohair, tbell
1 /*
2 * Copyright 2001-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_defNewGeneration.cpp.incl"
28 //
29 // DefNewGeneration functions.
31 // Methods of protected closure types.
33 DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) {
34 assert(g->level() == 0, "Optimized for youngest gen.");
35 }
36 void DefNewGeneration::IsAliveClosure::do_object(oop p) {
37 assert(false, "Do not call.");
38 }
39 bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
40 return (HeapWord*)p >= _g->reserved().end() || p->is_forwarded();
41 }
43 DefNewGeneration::KeepAliveClosure::
44 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
45 GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
46 assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind.");
47 _rs = (CardTableRS*)rs;
48 }
50 void DefNewGeneration::KeepAliveClosure::do_oop(oop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
51 void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
54 DefNewGeneration::FastKeepAliveClosure::
55 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
56 DefNewGeneration::KeepAliveClosure(cl) {
57 _boundary = g->reserved().end();
58 }
60 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
61 void DefNewGeneration::FastKeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
63 DefNewGeneration::EvacuateFollowersClosure::
64 EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
65 ScanClosure* cur, ScanClosure* older) :
66 _gch(gch), _level(level),
67 _scan_cur_or_nonheap(cur), _scan_older(older)
68 {}
70 void DefNewGeneration::EvacuateFollowersClosure::do_void() {
71 do {
72 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
73 _scan_older);
74 } while (!_gch->no_allocs_since_save_marks(_level));
75 }
77 DefNewGeneration::FastEvacuateFollowersClosure::
78 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
79 DefNewGeneration* gen,
80 FastScanClosure* cur, FastScanClosure* older) :
81 _gch(gch), _level(level), _gen(gen),
82 _scan_cur_or_nonheap(cur), _scan_older(older)
83 {}
85 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() {
86 do {
87 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
88 _scan_older);
89 } while (!_gch->no_allocs_since_save_marks(_level));
90 guarantee(_gen->promo_failure_scan_stack() == NULL
91 || _gen->promo_failure_scan_stack()->length() == 0,
92 "Failed to finish scan");
93 }
95 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) :
96 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
97 {
98 assert(_g->level() == 0, "Optimized for youngest generation");
99 _boundary = _g->reserved().end();
100 }
102 void ScanClosure::do_oop(oop* p) { ScanClosure::do_oop_work(p); }
103 void ScanClosure::do_oop(narrowOop* p) { ScanClosure::do_oop_work(p); }
105 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) :
106 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
107 {
108 assert(_g->level() == 0, "Optimized for youngest generation");
109 _boundary = _g->reserved().end();
110 }
112 void FastScanClosure::do_oop(oop* p) { FastScanClosure::do_oop_work(p); }
113 void FastScanClosure::do_oop(narrowOop* p) { FastScanClosure::do_oop_work(p); }
115 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) :
116 OopClosure(g->ref_processor()), _g(g)
117 {
118 assert(_g->level() == 0, "Optimized for youngest generation");
119 _boundary = _g->reserved().end();
120 }
122 void ScanWeakRefClosure::do_oop(oop* p) { ScanWeakRefClosure::do_oop_work(p); }
123 void ScanWeakRefClosure::do_oop(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); }
125 void FilteringClosure::do_oop(oop* p) { FilteringClosure::do_oop_work(p); }
126 void FilteringClosure::do_oop(narrowOop* p) { FilteringClosure::do_oop_work(p); }
128 DefNewGeneration::DefNewGeneration(ReservedSpace rs,
129 size_t initial_size,
130 int level,
131 const char* policy)
132 : Generation(rs, initial_size, level),
133 _objs_with_preserved_marks(NULL),
134 _preserved_marks_of_objs(NULL),
135 _promo_failure_scan_stack(NULL),
136 _promo_failure_drain_in_progress(false),
137 _should_allocate_from_space(false)
138 {
139 MemRegion cmr((HeapWord*)_virtual_space.low(),
140 (HeapWord*)_virtual_space.high());
141 Universe::heap()->barrier_set()->resize_covered_region(cmr);
143 if (GenCollectedHeap::heap()->collector_policy()->has_soft_ended_eden()) {
144 _eden_space = new ConcEdenSpace(this);
145 } else {
146 _eden_space = new EdenSpace(this);
147 }
148 _from_space = new ContiguousSpace();
149 _to_space = new ContiguousSpace();
151 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL)
152 vm_exit_during_initialization("Could not allocate a new gen space");
154 // Compute the maximum eden and survivor space sizes. These sizes
155 // are computed assuming the entire reserved space is committed.
156 // These values are exported as performance counters.
157 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
158 uintx size = _virtual_space.reserved_size();
159 _max_survivor_size = compute_survivor_size(size, alignment);
160 _max_eden_size = size - (2*_max_survivor_size);
162 // allocate the performance counters
164 // Generation counters -- generation 0, 3 subspaces
165 _gen_counters = new GenerationCounters("new", 0, 3, &_virtual_space);
166 _gc_counters = new CollectorCounters(policy, 0);
168 _eden_counters = new CSpaceCounters("eden", 0, _max_eden_size, _eden_space,
169 _gen_counters);
170 _from_counters = new CSpaceCounters("s0", 1, _max_survivor_size, _from_space,
171 _gen_counters);
172 _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space,
173 _gen_counters);
175 compute_space_boundaries(0);
176 update_counters();
177 _next_gen = NULL;
178 _tenuring_threshold = MaxTenuringThreshold;
179 _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize;
180 }
182 void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size) {
183 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
185 // Compute sizes
186 uintx size = _virtual_space.committed_size();
187 uintx survivor_size = compute_survivor_size(size, alignment);
188 uintx eden_size = size - (2*survivor_size);
189 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
191 if (eden_size < minimum_eden_size) {
192 // May happen due to 64Kb rounding, if so adjust eden size back up
193 minimum_eden_size = align_size_up(minimum_eden_size, alignment);
194 uintx maximum_survivor_size = (size - minimum_eden_size) / 2;
195 uintx unaligned_survivor_size =
196 align_size_down(maximum_survivor_size, alignment);
197 survivor_size = MAX2(unaligned_survivor_size, alignment);
198 eden_size = size - (2*survivor_size);
199 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
200 assert(eden_size >= minimum_eden_size, "just checking");
201 }
203 char *eden_start = _virtual_space.low();
204 char *from_start = eden_start + eden_size;
205 char *to_start = from_start + survivor_size;
206 char *to_end = to_start + survivor_size;
208 assert(to_end == _virtual_space.high(), "just checking");
209 assert(Space::is_aligned((HeapWord*)eden_start), "checking alignment");
210 assert(Space::is_aligned((HeapWord*)from_start), "checking alignment");
211 assert(Space::is_aligned((HeapWord*)to_start), "checking alignment");
213 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)from_start);
214 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start);
215 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
217 eden()->initialize(edenMR, (minimum_eden_size == 0));
218 // If minumum_eden_size != 0, we will not have cleared any
219 // portion of eden above its top. This can cause newly
220 // expanded space not to be mangled if using ZapUnusedHeapArea.
221 // We explicitly do such mangling here.
222 if (ZapUnusedHeapArea && (minimum_eden_size != 0)) {
223 eden()->mangle_unused_area();
224 }
225 from()->initialize(fromMR, true);
226 to()->initialize(toMR , true);
227 eden()->set_next_compaction_space(from());
228 // The to-space is normally empty before a compaction so need
229 // not be considered. The exception is during promotion
230 // failure handling when to-space can contain live objects.
231 from()->set_next_compaction_space(NULL);
232 }
234 void DefNewGeneration::swap_spaces() {
235 ContiguousSpace* s = from();
236 _from_space = to();
237 _to_space = s;
238 eden()->set_next_compaction_space(from());
239 // The to-space is normally empty before a compaction so need
240 // not be considered. The exception is during promotion
241 // failure handling when to-space can contain live objects.
242 from()->set_next_compaction_space(NULL);
244 if (UsePerfData) {
245 CSpaceCounters* c = _from_counters;
246 _from_counters = _to_counters;
247 _to_counters = c;
248 }
249 }
251 bool DefNewGeneration::expand(size_t bytes) {
252 MutexLocker x(ExpandHeap_lock);
253 bool success = _virtual_space.expand_by(bytes);
255 // Do not attempt an expand-to-the reserve size. The
256 // request should properly observe the maximum size of
257 // the generation so an expand-to-reserve should be
258 // unnecessary. Also a second call to expand-to-reserve
259 // value potentially can cause an undue expansion.
260 // For example if the first expand fail for unknown reasons,
261 // but the second succeeds and expands the heap to its maximum
262 // value.
263 if (GC_locker::is_active()) {
264 if (PrintGC && Verbose) {
265 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");
266 }
267 }
269 return success;
270 }
273 void DefNewGeneration::compute_new_size() {
274 // This is called after a gc that includes the following generation
275 // (which is required to exist.) So from-space will normally be empty.
276 // Note that we check both spaces, since if scavenge failed they revert roles.
277 // If not we bail out (otherwise we would have to relocate the objects)
278 if (!from()->is_empty() || !to()->is_empty()) {
279 return;
280 }
282 int next_level = level() + 1;
283 GenCollectedHeap* gch = GenCollectedHeap::heap();
284 assert(next_level < gch->_n_gens,
285 "DefNewGeneration cannot be an oldest gen");
287 Generation* next_gen = gch->_gens[next_level];
288 size_t old_size = next_gen->capacity();
289 size_t new_size_before = _virtual_space.committed_size();
290 size_t min_new_size = spec()->init_size();
291 size_t max_new_size = reserved().byte_size();
292 assert(min_new_size <= new_size_before &&
293 new_size_before <= max_new_size,
294 "just checking");
295 // All space sizes must be multiples of Generation::GenGrain.
296 size_t alignment = Generation::GenGrain;
298 // Compute desired new generation size based on NewRatio and
299 // NewSizeThreadIncrease
300 size_t desired_new_size = old_size/NewRatio;
301 int threads_count = Threads::number_of_non_daemon_threads();
302 size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
303 desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
305 // Adjust new generation size
306 desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);
307 assert(desired_new_size <= max_new_size, "just checking");
309 bool changed = false;
310 if (desired_new_size > new_size_before) {
311 size_t change = desired_new_size - new_size_before;
312 assert(change % alignment == 0, "just checking");
313 if (expand(change)) {
314 changed = true;
315 }
316 // If the heap failed to expand to the desired size,
317 // "changed" will be false. If the expansion failed
318 // (and at this point it was expected to succeed),
319 // ignore the failure (leaving "changed" as false).
320 }
321 if (desired_new_size < new_size_before && eden()->is_empty()) {
322 // bail out of shrinking if objects in eden
323 size_t change = new_size_before - desired_new_size;
324 assert(change % alignment == 0, "just checking");
325 _virtual_space.shrink_by(change);
326 changed = true;
327 }
328 if (changed) {
329 compute_space_boundaries(eden()->used());
330 MemRegion cmr((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
331 Universe::heap()->barrier_set()->resize_covered_region(cmr);
332 if (Verbose && PrintGC) {
333 size_t new_size_after = _virtual_space.committed_size();
334 size_t eden_size_after = eden()->capacity();
335 size_t survivor_size_after = from()->capacity();
336 gclog_or_tty->print("New generation size " SIZE_FORMAT "K->" SIZE_FORMAT "K [eden="
337 SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]",
338 new_size_before/K, new_size_after/K, eden_size_after/K, survivor_size_after/K);
339 if (WizardMode) {
340 gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]",
341 thread_increase_size/K, threads_count);
342 }
343 gclog_or_tty->cr();
344 }
345 }
346 }
348 void DefNewGeneration::object_iterate_since_last_GC(ObjectClosure* cl) {
349 // $$$ This may be wrong in case of "scavenge failure"?
350 eden()->object_iterate(cl);
351 }
353 void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl) {
354 assert(false, "NYI -- are you sure you want to call this?");
355 }
358 size_t DefNewGeneration::capacity() const {
359 return eden()->capacity()
360 + from()->capacity(); // to() is only used during scavenge
361 }
364 size_t DefNewGeneration::used() const {
365 return eden()->used()
366 + from()->used(); // to() is only used during scavenge
367 }
370 size_t DefNewGeneration::free() const {
371 return eden()->free()
372 + from()->free(); // to() is only used during scavenge
373 }
375 size_t DefNewGeneration::max_capacity() const {
376 const size_t alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
377 const size_t reserved_bytes = reserved().byte_size();
378 return reserved_bytes - compute_survivor_size(reserved_bytes, alignment);
379 }
381 size_t DefNewGeneration::unsafe_max_alloc_nogc() const {
382 return eden()->free();
383 }
385 size_t DefNewGeneration::capacity_before_gc() const {
386 return eden()->capacity();
387 }
389 size_t DefNewGeneration::contiguous_available() const {
390 return eden()->free();
391 }
394 HeapWord** DefNewGeneration::top_addr() const { return eden()->top_addr(); }
395 HeapWord** DefNewGeneration::end_addr() const { return eden()->end_addr(); }
397 void DefNewGeneration::object_iterate(ObjectClosure* blk) {
398 eden()->object_iterate(blk);
399 from()->object_iterate(blk);
400 }
403 void DefNewGeneration::space_iterate(SpaceClosure* blk,
404 bool usedOnly) {
405 blk->do_space(eden());
406 blk->do_space(from());
407 blk->do_space(to());
408 }
410 // The last collection bailed out, we are running out of heap space,
411 // so we try to allocate the from-space, too.
412 HeapWord* DefNewGeneration::allocate_from_space(size_t size) {
413 HeapWord* result = NULL;
414 if (PrintGC && Verbose) {
415 gclog_or_tty->print("DefNewGeneration::allocate_from_space(%u):"
416 " will_fail: %s"
417 " heap_lock: %s"
418 " free: " SIZE_FORMAT,
419 size,
420 GenCollectedHeap::heap()->incremental_collection_will_fail() ? "true" : "false",
421 Heap_lock->is_locked() ? "locked" : "unlocked",
422 from()->free());
423 }
424 if (should_allocate_from_space() || GC_locker::is_active_and_needs_gc()) {
425 if (Heap_lock->owned_by_self() ||
426 (SafepointSynchronize::is_at_safepoint() &&
427 Thread::current()->is_VM_thread())) {
428 // If the Heap_lock is not locked by this thread, this will be called
429 // again later with the Heap_lock held.
430 result = from()->allocate(size);
431 } else if (PrintGC && Verbose) {
432 gclog_or_tty->print_cr(" Heap_lock is not owned by self");
433 }
434 } else if (PrintGC && Verbose) {
435 gclog_or_tty->print_cr(" should_allocate_from_space: NOT");
436 }
437 if (PrintGC && Verbose) {
438 gclog_or_tty->print_cr(" returns %s", result == NULL ? "NULL" : "object");
439 }
440 return result;
441 }
443 HeapWord* DefNewGeneration::expand_and_allocate(size_t size,
444 bool is_tlab,
445 bool parallel) {
446 // We don't attempt to expand the young generation (but perhaps we should.)
447 return allocate(size, is_tlab);
448 }
451 void DefNewGeneration::collect(bool full,
452 bool clear_all_soft_refs,
453 size_t size,
454 bool is_tlab) {
455 assert(full || size > 0, "otherwise we don't want to collect");
456 GenCollectedHeap* gch = GenCollectedHeap::heap();
457 _next_gen = gch->next_gen(this);
458 assert(_next_gen != NULL,
459 "This must be the youngest gen, and not the only gen");
461 // If the next generation is too full to accomodate promotion
462 // from this generation, pass on collection; let the next generation
463 // do it.
464 if (!collection_attempt_is_safe()) {
465 gch->set_incremental_collection_will_fail();
466 return;
467 }
468 assert(to()->is_empty(), "Else not collection_attempt_is_safe");
470 init_assuming_no_promotion_failure();
472 TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
473 // Capture heap used before collection (for printing).
474 size_t gch_prev_used = gch->used();
476 SpecializationStats::clear();
478 // These can be shared for all code paths
479 IsAliveClosure is_alive(this);
480 ScanWeakRefClosure scan_weak_ref(this);
482 age_table()->clear();
483 to()->clear();
485 gch->rem_set()->prepare_for_younger_refs_iterate(false);
487 assert(gch->no_allocs_since_save_marks(0),
488 "save marks have not been newly set.");
490 // Weak refs.
491 // FIXME: Are these storage leaks, or are they resource objects?
492 #ifdef COMPILER2
493 ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy();
494 #else
495 ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy();
496 #endif // COMPILER2
498 // Not very pretty.
499 CollectorPolicy* cp = gch->collector_policy();
501 FastScanClosure fsc_with_no_gc_barrier(this, false);
502 FastScanClosure fsc_with_gc_barrier(this, true);
504 set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
505 FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
506 &fsc_with_no_gc_barrier,
507 &fsc_with_gc_barrier);
509 assert(gch->no_allocs_since_save_marks(0),
510 "save marks have not been newly set.");
512 gch->gen_process_strong_roots(_level,
513 true, // Process younger gens, if any, as
514 // strong roots.
515 false,// not collecting permanent generation.
516 SharedHeap::SO_AllClasses,
517 &fsc_with_gc_barrier,
518 &fsc_with_no_gc_barrier);
520 // "evacuate followers".
521 evacuate_followers.do_void();
523 FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
524 ref_processor()->process_discovered_references(
525 soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, NULL);
526 if (!promotion_failed()) {
527 // Swap the survivor spaces.
528 eden()->clear();
529 from()->clear();
530 swap_spaces();
532 assert(to()->is_empty(), "to space should be empty now");
534 // Set the desired survivor size to half the real survivor space
535 _tenuring_threshold =
536 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize);
538 if (PrintGC && !PrintGCDetails) {
539 gch->print_heap_change(gch_prev_used);
540 }
541 } else {
542 assert(HandlePromotionFailure,
543 "Should not be here unless promotion failure handling is on");
544 assert(_promo_failure_scan_stack != NULL &&
545 _promo_failure_scan_stack->length() == 0, "post condition");
547 // deallocate stack and it's elements
548 delete _promo_failure_scan_stack;
549 _promo_failure_scan_stack = NULL;
551 remove_forwarding_pointers();
552 if (PrintGCDetails) {
553 gclog_or_tty->print(" (promotion failed)");
554 }
555 // Add to-space to the list of space to compact
556 // when a promotion failure has occurred. In that
557 // case there can be live objects in to-space
558 // as a result of a partial evacuation of eden
559 // and from-space.
560 swap_spaces(); // For the sake of uniformity wrt ParNewGeneration::collect().
561 from()->set_next_compaction_space(to());
562 gch->set_incremental_collection_will_fail();
564 // Reset the PromotionFailureALot counters.
565 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
566 }
567 // set new iteration safe limit for the survivor spaces
568 from()->set_concurrent_iteration_safe_limit(from()->top());
569 to()->set_concurrent_iteration_safe_limit(to()->top());
570 SpecializationStats::print();
571 update_time_of_last_gc(os::javaTimeMillis());
572 }
574 class RemoveForwardPointerClosure: public ObjectClosure {
575 public:
576 void do_object(oop obj) {
577 obj->init_mark();
578 }
579 };
581 void DefNewGeneration::init_assuming_no_promotion_failure() {
582 _promotion_failed = false;
583 from()->set_next_compaction_space(NULL);
584 }
586 void DefNewGeneration::remove_forwarding_pointers() {
587 RemoveForwardPointerClosure rspc;
588 eden()->object_iterate(&rspc);
589 from()->object_iterate(&rspc);
590 // Now restore saved marks, if any.
591 if (_objs_with_preserved_marks != NULL) {
592 assert(_preserved_marks_of_objs != NULL, "Both or none.");
593 assert(_objs_with_preserved_marks->length() ==
594 _preserved_marks_of_objs->length(), "Both or none.");
595 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
596 oop obj = _objs_with_preserved_marks->at(i);
597 markOop m = _preserved_marks_of_objs->at(i);
598 obj->set_mark(m);
599 }
600 delete _objs_with_preserved_marks;
601 delete _preserved_marks_of_objs;
602 _objs_with_preserved_marks = NULL;
603 _preserved_marks_of_objs = NULL;
604 }
605 }
607 void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) {
608 if (m->must_be_preserved_for_promotion_failure(obj)) {
609 if (_objs_with_preserved_marks == NULL) {
610 assert(_preserved_marks_of_objs == NULL, "Both or none.");
611 _objs_with_preserved_marks = new (ResourceObj::C_HEAP)
612 GrowableArray<oop>(PreserveMarkStackSize, true);
613 _preserved_marks_of_objs = new (ResourceObj::C_HEAP)
614 GrowableArray<markOop>(PreserveMarkStackSize, true);
615 }
616 _objs_with_preserved_marks->push(obj);
617 _preserved_marks_of_objs->push(m);
618 }
619 }
621 void DefNewGeneration::handle_promotion_failure(oop old) {
622 preserve_mark_if_necessary(old, old->mark());
623 // forward to self
624 old->forward_to(old);
625 _promotion_failed = true;
627 push_on_promo_failure_scan_stack(old);
629 if (!_promo_failure_drain_in_progress) {
630 // prevent recursion in copy_to_survivor_space()
631 _promo_failure_drain_in_progress = true;
632 drain_promo_failure_scan_stack();
633 _promo_failure_drain_in_progress = false;
634 }
635 }
637 oop DefNewGeneration::copy_to_survivor_space(oop old) {
638 assert(is_in_reserved(old) && !old->is_forwarded(),
639 "shouldn't be scavenging this oop");
640 size_t s = old->size();
641 oop obj = NULL;
643 // Try allocating obj in to-space (unless too old)
644 if (old->age() < tenuring_threshold()) {
645 obj = (oop) to()->allocate(s);
646 }
648 // Otherwise try allocating obj tenured
649 if (obj == NULL) {
650 obj = _next_gen->promote(old, s);
651 if (obj == NULL) {
652 if (!HandlePromotionFailure) {
653 // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag
654 // is incorrectly set. In any case, its seriously wrong to be here!
655 vm_exit_out_of_memory(s*wordSize, "promotion");
656 }
658 handle_promotion_failure(old);
659 return old;
660 }
661 } else {
662 // Prefetch beyond obj
663 const intx interval = PrefetchCopyIntervalInBytes;
664 Prefetch::write(obj, interval);
666 // Copy obj
667 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)obj, s);
669 // Increment age if obj still in new generation
670 obj->incr_age();
671 age_table()->add(obj, s);
672 }
674 // Done, insert forward pointer to obj in this header
675 old->forward_to(obj);
677 return obj;
678 }
680 void DefNewGeneration::push_on_promo_failure_scan_stack(oop obj) {
681 if (_promo_failure_scan_stack == NULL) {
682 _promo_failure_scan_stack = new (ResourceObj::C_HEAP)
683 GrowableArray<oop>(40, true);
684 }
686 _promo_failure_scan_stack->push(obj);
687 }
689 void DefNewGeneration::drain_promo_failure_scan_stack() {
690 assert(_promo_failure_scan_stack != NULL, "precondition");
692 while (_promo_failure_scan_stack->length() > 0) {
693 oop obj = _promo_failure_scan_stack->pop();
694 obj->oop_iterate(_promo_failure_scan_stack_closure);
695 }
696 }
698 void DefNewGeneration::save_marks() {
699 eden()->set_saved_mark();
700 to()->set_saved_mark();
701 from()->set_saved_mark();
702 }
705 void DefNewGeneration::reset_saved_marks() {
706 eden()->reset_saved_mark();
707 to()->reset_saved_mark();
708 from()->reset_saved_mark();
709 }
712 bool DefNewGeneration::no_allocs_since_save_marks() {
713 assert(eden()->saved_mark_at_top(), "Violated spec - alloc in eden");
714 assert(from()->saved_mark_at_top(), "Violated spec - alloc in from");
715 return to()->saved_mark_at_top();
716 }
718 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
719 \
720 void DefNewGeneration:: \
721 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
722 cl->set_generation(this); \
723 eden()->oop_since_save_marks_iterate##nv_suffix(cl); \
724 to()->oop_since_save_marks_iterate##nv_suffix(cl); \
725 from()->oop_since_save_marks_iterate##nv_suffix(cl); \
726 cl->reset_generation(); \
727 save_marks(); \
728 }
730 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN)
732 #undef DefNew_SINCE_SAVE_MARKS_DEFN
734 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor,
735 size_t max_alloc_words) {
736 if (requestor == this || _promotion_failed) return;
737 assert(requestor->level() > level(), "DefNewGeneration must be youngest");
739 /* $$$ Assert this? "trace" is a "MarkSweep" function so that's not appropriate.
740 if (to_space->top() > to_space->bottom()) {
741 trace("to_space not empty when contribute_scratch called");
742 }
743 */
745 ContiguousSpace* to_space = to();
746 assert(to_space->end() >= to_space->top(), "pointers out of order");
747 size_t free_words = pointer_delta(to_space->end(), to_space->top());
748 if (free_words >= MinFreeScratchWords) {
749 ScratchBlock* sb = (ScratchBlock*)to_space->top();
750 sb->num_words = free_words;
751 sb->next = list;
752 list = sb;
753 }
754 }
756 bool DefNewGeneration::collection_attempt_is_safe() {
757 if (!to()->is_empty()) {
758 return false;
759 }
760 if (_next_gen == NULL) {
761 GenCollectedHeap* gch = GenCollectedHeap::heap();
762 _next_gen = gch->next_gen(this);
763 assert(_next_gen != NULL,
764 "This must be the youngest gen, and not the only gen");
765 }
767 // Decide if there's enough room for a full promotion
768 // When using extremely large edens, we effectively lose a
769 // large amount of old space. Use the "MaxLiveObjectEvacuationRatio"
770 // flag to reduce the minimum evacuation space requirements. If
771 // there is not enough space to evacuate eden during a scavenge,
772 // the VM will immediately exit with an out of memory error.
773 // This flag has not been tested
774 // with collectors other than simple mark & sweep.
775 //
776 // Note that with the addition of promotion failure handling, the
777 // VM will not immediately exit but will undo the young generation
778 // collection. The parameter is left here for compatibility.
779 const double evacuation_ratio = MaxLiveObjectEvacuationRatio / 100.0;
781 // worst_case_evacuation is based on "used()". For the case where this
782 // method is called after a collection, this is still appropriate because
783 // the case that needs to be detected is one in which a full collection
784 // has been done and has overflowed into the young generation. In that
785 // case a minor collection will fail (the overflow of the full collection
786 // means there is no space in the old generation for any promotion).
787 size_t worst_case_evacuation = (size_t)(used() * evacuation_ratio);
789 return _next_gen->promotion_attempt_is_safe(worst_case_evacuation,
790 HandlePromotionFailure);
791 }
793 void DefNewGeneration::gc_epilogue(bool full) {
794 // Check if the heap is approaching full after a collection has
795 // been done. Generally the young generation is empty at
796 // a minimum at the end of a collection. If it is not, then
797 // the heap is approaching full.
798 GenCollectedHeap* gch = GenCollectedHeap::heap();
799 clear_should_allocate_from_space();
800 if (collection_attempt_is_safe()) {
801 gch->clear_incremental_collection_will_fail();
802 } else {
803 gch->set_incremental_collection_will_fail();
804 if (full) { // we seem to be running out of space
805 set_should_allocate_from_space();
806 }
807 }
809 // update the generation and space performance counters
810 update_counters();
811 gch->collector_policy()->counters()->update_counters();
812 }
814 void DefNewGeneration::update_counters() {
815 if (UsePerfData) {
816 _eden_counters->update_all();
817 _from_counters->update_all();
818 _to_counters->update_all();
819 _gen_counters->update_all();
820 }
821 }
823 void DefNewGeneration::verify(bool allow_dirty) {
824 eden()->verify(allow_dirty);
825 from()->verify(allow_dirty);
826 to()->verify(allow_dirty);
827 }
829 void DefNewGeneration::print_on(outputStream* st) const {
830 Generation::print_on(st);
831 st->print(" eden");
832 eden()->print_on(st);
833 st->print(" from");
834 from()->print_on(st);
835 st->print(" to ");
836 to()->print_on(st);
837 }
840 const char* DefNewGeneration::name() const {
841 return "def new generation";
842 }
844 // Moved from inline file as they are not called inline
845 CompactibleSpace* DefNewGeneration::first_compaction_space() const {
846 return eden();
847 }
849 HeapWord* DefNewGeneration::allocate(size_t word_size,
850 bool is_tlab) {
851 // This is the slow-path allocation for the DefNewGeneration.
852 // Most allocations are fast-path in compiled code.
853 // We try to allocate from the eden. If that works, we are happy.
854 // Note that since DefNewGeneration supports lock-free allocation, we
855 // have to use it here, as well.
856 HeapWord* result = eden()->par_allocate(word_size);
857 if (result != NULL) {
858 return result;
859 }
860 do {
861 HeapWord* old_limit = eden()->soft_end();
862 if (old_limit < eden()->end()) {
863 // Tell the next generation we reached a limit.
864 HeapWord* new_limit =
865 next_gen()->allocation_limit_reached(eden(), eden()->top(), word_size);
866 if (new_limit != NULL) {
867 Atomic::cmpxchg_ptr(new_limit, eden()->soft_end_addr(), old_limit);
868 } else {
869 assert(eden()->soft_end() == eden()->end(),
870 "invalid state after allocation_limit_reached returned null");
871 }
872 } else {
873 // The allocation failed and the soft limit is equal to the hard limit,
874 // there are no reasons to do an attempt to allocate
875 assert(old_limit == eden()->end(), "sanity check");
876 break;
877 }
878 // Try to allocate until succeeded or the soft limit can't be adjusted
879 result = eden()->par_allocate(word_size);
880 } while (result == NULL);
882 // If the eden is full and the last collection bailed out, we are running
883 // out of heap space, and we try to allocate the from-space, too.
884 // allocate_from_space can't be inlined because that would introduce a
885 // circular dependency at compile time.
886 if (result == NULL) {
887 result = allocate_from_space(word_size);
888 }
889 return result;
890 }
892 HeapWord* DefNewGeneration::par_allocate(size_t word_size,
893 bool is_tlab) {
894 return eden()->par_allocate(word_size);
895 }
897 void DefNewGeneration::gc_prologue(bool full) {
898 // Ensure that _end and _soft_end are the same in eden space.
899 eden()->set_soft_end(eden()->end());
900 }
902 size_t DefNewGeneration::tlab_capacity() const {
903 return eden()->capacity();
904 }
906 size_t DefNewGeneration::unsafe_max_tlab_alloc() const {
907 return unsafe_max_alloc_nogc();
908 }