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 2001-2008 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) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
54 void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
55
56
57 DefNewGeneration::FastKeepAliveClosure::
58 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
59 DefNewGeneration::KeepAliveClosure(cl) {
60 _boundary = g->reserved().end();
61 }
62
63 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
64 void DefNewGeneration::FastKeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::FastKeepAliveClosure::do_oop_work(p); }
65
66 DefNewGeneration::EvacuateFollowersClosure::
67 EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
68 ScanClosure* cur, ScanClosure* older) :
69 _gch(gch), _level(level),
70 _scan_cur_or_nonheap(cur), _scan_older(older)
71 {}
72
73 void DefNewGeneration::EvacuateFollowersClosure::do_void() {
74 do {
75 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
76 _scan_older);
77 } while (!_gch->no_allocs_since_save_marks(_level));
78 }
79
80 DefNewGeneration::FastEvacuateFollowersClosure::
81 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
82 DefNewGeneration* gen,
83 FastScanClosure* cur, FastScanClosure* older) :
84 _gch(gch), _level(level), _gen(gen),
85 _scan_cur_or_nonheap(cur), _scan_older(older)
86 {}
87
88 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() {
89 do {
90 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
91 _scan_older);
92 } while (!_gch->no_allocs_since_save_marks(_level));
93 guarantee(_gen->promo_failure_scan_stack() == NULL
94 || _gen->promo_failure_scan_stack()->length() == 0,
95 "Failed to finish scan");
96 }
97
98 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) :
99 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
100 {
101 assert(_g->level() == 0, "Optimized for youngest generation");
102 _boundary = _g->reserved().end();
103 }
104
105 void ScanClosure::do_oop(oop* p) { ScanClosure::do_oop_work(p); }
106 void ScanClosure::do_oop(narrowOop* p) { ScanClosure::do_oop_work(p); }
107
108 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) :
109 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
110 {
111 assert(_g->level() == 0, "Optimized for youngest generation");
112 _boundary = _g->reserved().end();
113 }
114
115 void FastScanClosure::do_oop(oop* p) { FastScanClosure::do_oop_work(p); }
116 void FastScanClosure::do_oop(narrowOop* p) { FastScanClosure::do_oop_work(p); }
117
118 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) :
119 OopClosure(g->ref_processor()), _g(g)
120 {
121 assert(_g->level() == 0, "Optimized for youngest generation");
122 _boundary = _g->reserved().end();
123 }
124
125 void ScanWeakRefClosure::do_oop(oop* p) { ScanWeakRefClosure::do_oop_work(p); }
126 void ScanWeakRefClosure::do_oop(narrowOop* p) { ScanWeakRefClosure::do_oop_work(p); }
127
128 void FilteringClosure::do_oop(oop* p) { FilteringClosure::do_oop_work(p); }
129 void FilteringClosure::do_oop(narrowOop* p) { FilteringClosure::do_oop_work(p); }
130
131 DefNewGeneration::DefNewGeneration(ReservedSpace rs,
132 size_t initial_size,
133 int level,
134 const char* policy)
135 : Generation(rs, initial_size, level),
136 _objs_with_preserved_marks(NULL),
137 _preserved_marks_of_objs(NULL),
138 _promo_failure_scan_stack(NULL),
139 _promo_failure_drain_in_progress(false),
140 _should_allocate_from_space(false)
141 {
142 MemRegion cmr((HeapWord*)_virtual_space.low(),
143 (HeapWord*)_virtual_space.high());
144 Universe::heap()->barrier_set()->resize_covered_region(cmr);
145
146 if (GenCollectedHeap::heap()->collector_policy()->has_soft_ended_eden()) {
147 _eden_space = new ConcEdenSpace(this);
148 } else {
149 _eden_space = new EdenSpace(this);
150 }
151 _from_space = new ContiguousSpace();
152 _to_space = new ContiguousSpace();
153
154 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL)
155 vm_exit_during_initialization("Could not allocate a new gen space");
156
157 // Compute the maximum eden and survivor space sizes. These sizes
158 // are computed assuming the entire reserved space is committed.
159 // These values are exported as performance counters.
160 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
161 uintx size = _virtual_space.reserved_size();
162 _max_survivor_size = compute_survivor_size(size, alignment);
163 _max_eden_size = size - (2*_max_survivor_size);
164
165 // allocate the performance counters
166
167 // Generation counters -- generation 0, 3 subspaces
168 _gen_counters = new GenerationCounters("new", 0, 3, &_virtual_space);
169 _gc_counters = new CollectorCounters(policy, 0);
170
171 _eden_counters = new CSpaceCounters("eden", 0, _max_eden_size, _eden_space,
172 _gen_counters);
173 _from_counters = new CSpaceCounters("s0", 1, _max_survivor_size, _from_space,
174 _gen_counters);
175 _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space,
176 _gen_counters);
177
178 compute_space_boundaries(0, SpaceDecorator::Clear, SpaceDecorator::Mangle);
179 update_counters();
180 _next_gen = NULL;
181 _tenuring_threshold = MaxTenuringThreshold;
182 _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize;
183 }
184
185 void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size,
186 bool clear_space,
187 bool mangle_space) {
188 uintx alignment =
189 GenCollectedHeap::heap()->collector_policy()->min_alignment();
190
191 // If the spaces are being cleared (only done at heap initialization
192 // currently), the survivor spaces need not be empty.
193 // Otherwise, no care is taken for used areas in the survivor spaces
194 // so check.
195 assert(clear_space || (to()->is_empty() && from()->is_empty()),
196 "Initialization of the survivor spaces assumes these are empty");
197
198 // Compute sizes
199 uintx size = _virtual_space.committed_size();
200 uintx survivor_size = compute_survivor_size(size, alignment);
201 uintx eden_size = size - (2*survivor_size);
202 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
203
204 if (eden_size < minimum_eden_size) {
205 // May happen due to 64Kb rounding, if so adjust eden size back up
206 minimum_eden_size = align_size_up(minimum_eden_size, alignment);
207 uintx maximum_survivor_size = (size - minimum_eden_size) / 2;
208 uintx unaligned_survivor_size =
209 align_size_down(maximum_survivor_size, alignment);
210 survivor_size = MAX2(unaligned_survivor_size, alignment);
211 eden_size = size - (2*survivor_size);
212 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
213 assert(eden_size >= minimum_eden_size, "just checking");
214 }
215
216 char *eden_start = _virtual_space.low();
217 char *from_start = eden_start + eden_size;
218 char *to_start = from_start + survivor_size;
219 char *to_end = to_start + survivor_size;
220
221 assert(to_end == _virtual_space.high(), "just checking");
222 assert(Space::is_aligned((HeapWord*)eden_start), "checking alignment");
223 assert(Space::is_aligned((HeapWord*)from_start), "checking alignment");
224 assert(Space::is_aligned((HeapWord*)to_start), "checking alignment");
225
226 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)from_start);
227 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start);
228 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
229
230 // A minimum eden size implies that there is a part of eden that
231 // is being used and that affects the initialization of any
232 // newly formed eden.
233 bool live_in_eden = minimum_eden_size > 0;
234
235 // If not clearing the spaces, do some checking to verify that
236 // the space are already mangled.
237 if (!clear_space) {
238 // Must check mangling before the spaces are reshaped. Otherwise,
239 // the bottom or end of one space may have moved into another
240 // a failure of the check may not correctly indicate which space
241 // is not properly mangled.
242 if (ZapUnusedHeapArea) {
243 HeapWord* limit = (HeapWord*) _virtual_space.high();
244 eden()->check_mangled_unused_area(limit);
245 from()->check_mangled_unused_area(limit);
246 to()->check_mangled_unused_area(limit);
247 }
248 }
249
250 // Reset the spaces for their new regions.
251 eden()->initialize(edenMR,
252 clear_space && !live_in_eden,
253 SpaceDecorator::Mangle);
254 // If clear_space and live_in_eden, we will not have cleared any
255 // portion of eden above its top. This can cause newly
256 // expanded space not to be mangled if using ZapUnusedHeapArea.
257 // We explicitly do such mangling here.
258 if (ZapUnusedHeapArea && clear_space && live_in_eden && mangle_space) {
259 eden()->mangle_unused_area();
260 }
261 from()->initialize(fromMR, clear_space, mangle_space);
262 to()->initialize(toMR, clear_space, mangle_space);
263
264 // Set next compaction spaces.
265 eden()->set_next_compaction_space(from());
266 // The to-space is normally empty before a compaction so need
267 // not be considered. The exception is during promotion
268 // failure handling when to-space can contain live objects.
269 from()->set_next_compaction_space(NULL);
270 }
271
272 void DefNewGeneration::swap_spaces() {
273 ContiguousSpace* s = from();
274 _from_space = to();
275 _to_space = s;
276 eden()->set_next_compaction_space(from());
277 // The to-space is normally empty before a compaction so need
278 // not be considered. The exception is during promotion
279 // failure handling when to-space can contain live objects.
280 from()->set_next_compaction_space(NULL);
281
282 if (UsePerfData) {
283 CSpaceCounters* c = _from_counters;
284 _from_counters = _to_counters;
285 _to_counters = c;
286 }
287 }
288
289 bool DefNewGeneration::expand(size_t bytes) {
290 MutexLocker x(ExpandHeap_lock);
291 HeapWord* prev_high = (HeapWord*) _virtual_space.high();
292 bool success = _virtual_space.expand_by(bytes);
293 if (success && ZapUnusedHeapArea) {
294 // Mangle newly committed space immediately because it
295 // can be done here more simply that after the new
296 // spaces have been computed.
297 HeapWord* new_high = (HeapWord*) _virtual_space.high();
298 MemRegion mangle_region(prev_high, new_high);
299 SpaceMangler::mangle_region(mangle_region);
300 }
301
302 // Do not attempt an expand-to-the reserve size. The
303 // request should properly observe the maximum size of
304 // the generation so an expand-to-reserve should be
305 // unnecessary. Also a second call to expand-to-reserve
306 // value potentially can cause an undue expansion.
307 // For example if the first expand fail for unknown reasons,
308 // but the second succeeds and expands the heap to its maximum
309 // value.
310 if (GC_locker::is_active()) {
311 if (PrintGC && Verbose) {
312 gclog_or_tty->print_cr("Garbage collection disabled, "
313 "expanded heap instead");
314 }
315 }
316
317 return success;
318 }
319
320
321 void DefNewGeneration::compute_new_size() {
322 // This is called after a gc that includes the following generation
323 // (which is required to exist.) So from-space will normally be empty.
324 // Note that we check both spaces, since if scavenge failed they revert roles.
325 // If not we bail out (otherwise we would have to relocate the objects)
326 if (!from()->is_empty() || !to()->is_empty()) {
327 return;
328 }
329
330 int next_level = level() + 1;
331 GenCollectedHeap* gch = GenCollectedHeap::heap();
332 assert(next_level < gch->_n_gens,
333 "DefNewGeneration cannot be an oldest gen");
334
335 Generation* next_gen = gch->_gens[next_level];
336 size_t old_size = next_gen->capacity();
337 size_t new_size_before = _virtual_space.committed_size();
338 size_t min_new_size = spec()->init_size();
339 size_t max_new_size = reserved().byte_size();
340 assert(min_new_size <= new_size_before &&
341 new_size_before <= max_new_size,
342 "just checking");
343 // All space sizes must be multiples of Generation::GenGrain.
344 size_t alignment = Generation::GenGrain;
345
346 // Compute desired new generation size based on NewRatio and
347 // NewSizeThreadIncrease
348 size_t desired_new_size = old_size/NewRatio;
349 int threads_count = Threads::number_of_non_daemon_threads();
350 size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
351 desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
352
353 // Adjust new generation size
354 desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);
355 assert(desired_new_size <= max_new_size, "just checking");
356
357 bool changed = false;
358 if (desired_new_size > new_size_before) {
359 size_t change = desired_new_size - new_size_before;
360 assert(change % alignment == 0, "just checking");
361 if (expand(change)) {
362 changed = true;
363 }
364 // If the heap failed to expand to the desired size,
365 // "changed" will be false. If the expansion failed
366 // (and at this point it was expected to succeed),
367 // ignore the failure (leaving "changed" as false).
368 }
369 if (desired_new_size < new_size_before && eden()->is_empty()) {
370 // bail out of shrinking if objects in eden
371 size_t change = new_size_before - desired_new_size;
372 assert(change % alignment == 0, "just checking");
373 _virtual_space.shrink_by(change);
374 changed = true;
375 }
376 if (changed) {
377 // The spaces have already been mangled at this point but
378 // may not have been cleared (set top = bottom) and should be.
379 // Mangling was done when the heap was being expanded.
380 compute_space_boundaries(eden()->used(),
381 SpaceDecorator::Clear,
382 SpaceDecorator::DontMangle);
383 MemRegion cmr((HeapWord*)_virtual_space.low(),
384 (HeapWord*)_virtual_space.high());
385 Universe::heap()->barrier_set()->resize_covered_region(cmr);
386 if (Verbose && PrintGC) {
387 size_t new_size_after = _virtual_space.committed_size();
388 size_t eden_size_after = eden()->capacity();
389 size_t survivor_size_after = from()->capacity();
390 gclog_or_tty->print("New generation size " SIZE_FORMAT "K->"
391 SIZE_FORMAT "K [eden="
392 SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]",
393 new_size_before/K, new_size_after/K,
394 eden_size_after/K, survivor_size_after/K);
395 if (WizardMode) {
396 gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]",
397 thread_increase_size/K, threads_count);
398 }
399 gclog_or_tty->cr();
400 }
401 }
402 }
403
404 void DefNewGeneration::object_iterate_since_last_GC(ObjectClosure* cl) {
405 // $$$ This may be wrong in case of "scavenge failure"?
406 eden()->object_iterate(cl);
407 }
408
409 void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl) {
410 assert(false, "NYI -- are you sure you want to call this?");
411 }
412
413
414 size_t DefNewGeneration::capacity() const {
415 return eden()->capacity()
416 + from()->capacity(); // to() is only used during scavenge
417 }
418
419
420 size_t DefNewGeneration::used() const {
421 return eden()->used()
422 + from()->used(); // to() is only used during scavenge
423 }
424
425
426 size_t DefNewGeneration::free() const {
427 return eden()->free()
428 + from()->free(); // to() is only used during scavenge
429 }
430
431 size_t DefNewGeneration::max_capacity() const {
432 const size_t alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
433 const size_t reserved_bytes = reserved().byte_size();
434 return reserved_bytes - compute_survivor_size(reserved_bytes, alignment);
435 }
436
437 size_t DefNewGeneration::unsafe_max_alloc_nogc() const {
438 return eden()->free();
439 }
440
441 size_t DefNewGeneration::capacity_before_gc() const {
442 return eden()->capacity();
443 }
444
445 size_t DefNewGeneration::contiguous_available() const {
446 return eden()->free();
447 }
448
449
450 HeapWord** DefNewGeneration::top_addr() const { return eden()->top_addr(); }
451 HeapWord** DefNewGeneration::end_addr() const { return eden()->end_addr(); }
452
453 void DefNewGeneration::object_iterate(ObjectClosure* blk) {
454 eden()->object_iterate(blk);
455 from()->object_iterate(blk);
456 }
457
458
459 void DefNewGeneration::space_iterate(SpaceClosure* blk,
460 bool usedOnly) {
461 blk->do_space(eden());
462 blk->do_space(from());
463 blk->do_space(to());
464 }
465
466 // The last collection bailed out, we are running out of heap space,
467 // so we try to allocate the from-space, too.
468 HeapWord* DefNewGeneration::allocate_from_space(size_t size) {
469 HeapWord* result = NULL;
470 if (PrintGC && Verbose) {
471 gclog_or_tty->print("DefNewGeneration::allocate_from_space(%u):"
472 " will_fail: %s"
473 " heap_lock: %s"
474 " free: " SIZE_FORMAT,
475 size,
476 GenCollectedHeap::heap()->incremental_collection_will_fail() ? "true" : "false",
477 Heap_lock->is_locked() ? "locked" : "unlocked",
478 from()->free());
479 }
480 if (should_allocate_from_space() || GC_locker::is_active_and_needs_gc()) {
481 if (Heap_lock->owned_by_self() ||
482 (SafepointSynchronize::is_at_safepoint() &&
483 Thread::current()->is_VM_thread())) {
484 // If the Heap_lock is not locked by this thread, this will be called
485 // again later with the Heap_lock held.
486 result = from()->allocate(size);
487 } else if (PrintGC && Verbose) {
488 gclog_or_tty->print_cr(" Heap_lock is not owned by self");
489 }
490 } else if (PrintGC && Verbose) {
491 gclog_or_tty->print_cr(" should_allocate_from_space: NOT");
492 }
493 if (PrintGC && Verbose) {
494 gclog_or_tty->print_cr(" returns %s", result == NULL ? "NULL" : "object");
495 }
496 return result;
497 }
498
499 HeapWord* DefNewGeneration::expand_and_allocate(size_t size,
500 bool is_tlab,
501 bool parallel) {
502 // We don't attempt to expand the young generation (but perhaps we should.)
503 return allocate(size, is_tlab);
504 }
505
506
507 void DefNewGeneration::collect(bool full,
508 bool clear_all_soft_refs,
509 size_t size,
510 bool is_tlab) {
511 assert(full || size > 0, "otherwise we don't want to collect");
512 GenCollectedHeap* gch = GenCollectedHeap::heap();
513 _next_gen = gch->next_gen(this);
514 assert(_next_gen != NULL,
515 "This must be the youngest gen, and not the only gen");
516
517 // If the next generation is too full to accomodate promotion
518 // from this generation, pass on collection; let the next generation
519 // do it.
520 if (!collection_attempt_is_safe()) {
521 gch->set_incremental_collection_will_fail();
522 return;
523 }
524 assert(to()->is_empty(), "Else not collection_attempt_is_safe");
525
526 init_assuming_no_promotion_failure();
527
528 TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
529 // Capture heap used before collection (for printing).
530 size_t gch_prev_used = gch->used();
531
532 SpecializationStats::clear();
533
534 // These can be shared for all code paths
535 IsAliveClosure is_alive(this);
536 ScanWeakRefClosure scan_weak_ref(this);
537
538 age_table()->clear();
539 to()->clear(SpaceDecorator::Mangle);
540
541 gch->rem_set()->prepare_for_younger_refs_iterate(false);
542
543 assert(gch->no_allocs_since_save_marks(0),
544 "save marks have not been newly set.");
545
546 // Not very pretty.
547 CollectorPolicy* cp = gch->collector_policy();
548
549 FastScanClosure fsc_with_no_gc_barrier(this, false);
550 FastScanClosure fsc_with_gc_barrier(this, true);
551
552 set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
553 FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
554 &fsc_with_no_gc_barrier,
555 &fsc_with_gc_barrier);
556
557 assert(gch->no_allocs_since_save_marks(0),
558 "save marks have not been newly set.");
559
560 gch->gen_process_strong_roots(_level,
561 true, // Process younger gens, if any, as
562 // strong roots.
563 false,// not collecting permanent generation.
564 SharedHeap::SO_AllClasses,
565 &fsc_with_gc_barrier,
566 &fsc_with_no_gc_barrier);
567
568 // "evacuate followers".
569 evacuate_followers.do_void();
570
571 FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
572 ReferenceProcessor* rp = ref_processor();
573 rp->setup_policy(clear_all_soft_refs);
574 rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
575 NULL);
576 if (!promotion_failed()) {
577 // Swap the survivor spaces.
578 eden()->clear(SpaceDecorator::Mangle);
579 from()->clear(SpaceDecorator::Mangle);
580 if (ZapUnusedHeapArea) {
581 // This is now done here because of the piece-meal mangling which
582 // can check for valid mangling at intermediate points in the
583 // collection(s). When a minor collection fails to collect
584 // sufficient space resizing of the young generation can occur
585 // an redistribute the spaces in the young generation. Mangle
586 // here so that unzapped regions don't get distributed to
587 // other spaces.
588 to()->mangle_unused_area();
589 }
590 swap_spaces();
591
592 assert(to()->is_empty(), "to space should be empty now");
593
594 // Set the desired survivor size to half the real survivor space
595 _tenuring_threshold =
596 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize);
597
598 if (PrintGC && !PrintGCDetails) {
599 gch->print_heap_change(gch_prev_used);
600 }
601 } else {
602 assert(HandlePromotionFailure,
603 "Should not be here unless promotion failure handling is on");
604 assert(_promo_failure_scan_stack != NULL &&
605 _promo_failure_scan_stack->length() == 0, "post condition");
606
607 // deallocate stack and it's elements
608 delete _promo_failure_scan_stack;
609 _promo_failure_scan_stack = NULL;
610
611 remove_forwarding_pointers();
612 if (PrintGCDetails) {
613 gclog_or_tty->print(" (promotion failed)");
614 }
615 // Add to-space to the list of space to compact
616 // when a promotion failure has occurred. In that
617 // case there can be live objects in to-space
618 // as a result of a partial evacuation of eden
619 // and from-space.
620 swap_spaces(); // For the sake of uniformity wrt ParNewGeneration::collect().
621 from()->set_next_compaction_space(to());
622 gch->set_incremental_collection_will_fail();
623
624 // Reset the PromotionFailureALot counters.
625 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
626 }
627 // set new iteration safe limit for the survivor spaces
628 from()->set_concurrent_iteration_safe_limit(from()->top());
629 to()->set_concurrent_iteration_safe_limit(to()->top());
630 SpecializationStats::print();
631 update_time_of_last_gc(os::javaTimeMillis());
632 }
633
634 class RemoveForwardPointerClosure: public ObjectClosure {
635 public:
636 void do_object(oop obj) {
637 obj->init_mark();
638 }
639 };
640
641 void DefNewGeneration::init_assuming_no_promotion_failure() {
642 _promotion_failed = false;
643 from()->set_next_compaction_space(NULL);
644 }
645
646 void DefNewGeneration::remove_forwarding_pointers() {
647 RemoveForwardPointerClosure rspc;
648 eden()->object_iterate(&rspc);
649 from()->object_iterate(&rspc);
650 // Now restore saved marks, if any.
651 if (_objs_with_preserved_marks != NULL) {
652 assert(_preserved_marks_of_objs != NULL, "Both or none.");
653 assert(_objs_with_preserved_marks->length() ==
654 _preserved_marks_of_objs->length(), "Both or none.");
655 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
656 oop obj = _objs_with_preserved_marks->at(i);
657 markOop m = _preserved_marks_of_objs->at(i);
658 obj->set_mark(m);
659 }
660 delete _objs_with_preserved_marks;
661 delete _preserved_marks_of_objs;
662 _objs_with_preserved_marks = NULL;
663 _preserved_marks_of_objs = NULL;
664 }
665 }
666
667 void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) {
668 if (m->must_be_preserved_for_promotion_failure(obj)) {
669 if (_objs_with_preserved_marks == NULL) {
670 assert(_preserved_marks_of_objs == NULL, "Both or none.");
671 _objs_with_preserved_marks = new (ResourceObj::C_HEAP)
672 GrowableArray<oop>(PreserveMarkStackSize, true);
673 _preserved_marks_of_objs = new (ResourceObj::C_HEAP)
674 GrowableArray<markOop>(PreserveMarkStackSize, true);
675 }
676 _objs_with_preserved_marks->push(obj);
677 _preserved_marks_of_objs->push(m);
678 }
679 }
680
681 void DefNewGeneration::handle_promotion_failure(oop old) {
682 preserve_mark_if_necessary(old, old->mark());
683 // forward to self
684 old->forward_to(old);
685 _promotion_failed = true;
686
687 push_on_promo_failure_scan_stack(old);
688
689 if (!_promo_failure_drain_in_progress) {
690 // prevent recursion in copy_to_survivor_space()
691 _promo_failure_drain_in_progress = true;
692 drain_promo_failure_scan_stack();
693 _promo_failure_drain_in_progress = false;
694 }
695 }
696
697 oop DefNewGeneration::copy_to_survivor_space(oop old) {
698 assert(is_in_reserved(old) && !old->is_forwarded(),
699 "shouldn't be scavenging this oop");
700 size_t s = old->size();
701 oop obj = NULL;
702
703 // Try allocating obj in to-space (unless too old)
704 if (old->age() < tenuring_threshold()) {
705 obj = (oop) to()->allocate(s);
706 }
707
708 // Otherwise try allocating obj tenured
709 if (obj == NULL) {
710 obj = _next_gen->promote(old, s);
711 if (obj == NULL) {
712 if (!HandlePromotionFailure) {
713 // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag
714 // is incorrectly set. In any case, its seriously wrong to be here!
715 vm_exit_out_of_memory(s*wordSize, "promotion");
716 }
717
718 handle_promotion_failure(old);
719 return old;
720 }
721 } else {
722 // Prefetch beyond obj
723 const intx interval = PrefetchCopyIntervalInBytes;
724 Prefetch::write(obj, interval);
725
726 // Copy obj
727 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)obj, s);
728
729 // Increment age if obj still in new generation
730 obj->incr_age();
731 age_table()->add(obj, s);
732 }
733
734 // Done, insert forward pointer to obj in this header
735 old->forward_to(obj);
736
737 return obj;
738 }
739
740 void DefNewGeneration::push_on_promo_failure_scan_stack(oop obj) {
741 if (_promo_failure_scan_stack == NULL) {
742 _promo_failure_scan_stack = new (ResourceObj::C_HEAP)
743 GrowableArray<oop>(40, true);
744 }
745
746 _promo_failure_scan_stack->push(obj);
747 }
748
749 void DefNewGeneration::drain_promo_failure_scan_stack() {
750 assert(_promo_failure_scan_stack != NULL, "precondition");
751
752 while (_promo_failure_scan_stack->length() > 0) {
753 oop obj = _promo_failure_scan_stack->pop();
754 obj->oop_iterate(_promo_failure_scan_stack_closure);
755 }
756 }
757
758 void DefNewGeneration::save_marks() {
759 eden()->set_saved_mark();
760 to()->set_saved_mark();
761 from()->set_saved_mark();
762 }
763
764
765 void DefNewGeneration::reset_saved_marks() {
766 eden()->reset_saved_mark();
767 to()->reset_saved_mark();
768 from()->reset_saved_mark();
769 }
770
771
772 bool DefNewGeneration::no_allocs_since_save_marks() {
773 assert(eden()->saved_mark_at_top(), "Violated spec - alloc in eden");
774 assert(from()->saved_mark_at_top(), "Violated spec - alloc in from");
775 return to()->saved_mark_at_top();
776 }
777
778 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
779 \
780 void DefNewGeneration:: \
781 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
782 cl->set_generation(this); \
783 eden()->oop_since_save_marks_iterate##nv_suffix(cl); \
784 to()->oop_since_save_marks_iterate##nv_suffix(cl); \
785 from()->oop_since_save_marks_iterate##nv_suffix(cl); \
786 cl->reset_generation(); \
787 save_marks(); \
788 }
789
790 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN)
791
792 #undef DefNew_SINCE_SAVE_MARKS_DEFN
793
794 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor,
795 size_t max_alloc_words) {
796 if (requestor == this || _promotion_failed) return;
797 assert(requestor->level() > level(), "DefNewGeneration must be youngest");
798
799 /* $$$ Assert this? "trace" is a "MarkSweep" function so that's not appropriate.
800 if (to_space->top() > to_space->bottom()) {
801 trace("to_space not empty when contribute_scratch called");
802 }
803 */
804
805 ContiguousSpace* to_space = to();
806 assert(to_space->end() >= to_space->top(), "pointers out of order");
807 size_t free_words = pointer_delta(to_space->end(), to_space->top());
808 if (free_words >= MinFreeScratchWords) {
809 ScratchBlock* sb = (ScratchBlock*)to_space->top();
810 sb->num_words = free_words;
811 sb->next = list;
812 list = sb;
813 }
814 }
815
816 void DefNewGeneration::reset_scratch() {
817 // If contributing scratch in to_space, mangle all of
818 // to_space if ZapUnusedHeapArea. This is needed because
819 // top is not maintained while using to-space as scratch.
820 if (ZapUnusedHeapArea) {
821 to()->mangle_unused_area_complete();
822 }
823 }
824
825 bool DefNewGeneration::collection_attempt_is_safe() {
826 if (!to()->is_empty()) {
827 return false;
828 }
829 if (_next_gen == NULL) {
830 GenCollectedHeap* gch = GenCollectedHeap::heap();
831 _next_gen = gch->next_gen(this);
832 assert(_next_gen != NULL,
833 "This must be the youngest gen, and not the only gen");
834 }
835
836 // Decide if there's enough room for a full promotion
837 // When using extremely large edens, we effectively lose a
838 // large amount of old space. Use the "MaxLiveObjectEvacuationRatio"
839 // flag to reduce the minimum evacuation space requirements. If
840 // there is not enough space to evacuate eden during a scavenge,
841 // the VM will immediately exit with an out of memory error.
842 // This flag has not been tested
843 // with collectors other than simple mark & sweep.
844 //
845 // Note that with the addition of promotion failure handling, the
846 // VM will not immediately exit but will undo the young generation
847 // collection. The parameter is left here for compatibility.
848 const double evacuation_ratio = MaxLiveObjectEvacuationRatio / 100.0;
849
850 // worst_case_evacuation is based on "used()". For the case where this
851 // method is called after a collection, this is still appropriate because
852 // the case that needs to be detected is one in which a full collection
853 // has been done and has overflowed into the young generation. In that
854 // case a minor collection will fail (the overflow of the full collection
855 // means there is no space in the old generation for any promotion).
856 size_t worst_case_evacuation = (size_t)(used() * evacuation_ratio);
857
858 return _next_gen->promotion_attempt_is_safe(worst_case_evacuation,
859 HandlePromotionFailure);
860 }
861
862 void DefNewGeneration::gc_epilogue(bool full) {
863 // Check if the heap is approaching full after a collection has
864 // been done. Generally the young generation is empty at
865 // a minimum at the end of a collection. If it is not, then
866 // the heap is approaching full.
867 GenCollectedHeap* gch = GenCollectedHeap::heap();
868 clear_should_allocate_from_space();
869 if (collection_attempt_is_safe()) {
870 gch->clear_incremental_collection_will_fail();
871 } else {
872 gch->set_incremental_collection_will_fail();
873 if (full) { // we seem to be running out of space
874 set_should_allocate_from_space();
875 }
876 }
877
878 if (ZapUnusedHeapArea) {
879 eden()->check_mangled_unused_area_complete();
880 from()->check_mangled_unused_area_complete();
881 to()->check_mangled_unused_area_complete();
882 }
883
884 // update the generation and space performance counters
885 update_counters();
886 gch->collector_policy()->counters()->update_counters();
887 }
888
889 void DefNewGeneration::record_spaces_top() {
890 assert(ZapUnusedHeapArea, "Not mangling unused space");
891 eden()->set_top_for_allocations();
892 to()->set_top_for_allocations();
893 from()->set_top_for_allocations();
894 }
895
896
897 void DefNewGeneration::update_counters() {
898 if (UsePerfData) {
899 _eden_counters->update_all();
900 _from_counters->update_all();
901 _to_counters->update_all();
902 _gen_counters->update_all();
903 }
904 }
905
906 void DefNewGeneration::verify(bool allow_dirty) {
907 eden()->verify(allow_dirty);
908 from()->verify(allow_dirty);
909 to()->verify(allow_dirty);
910 }
911
912 void DefNewGeneration::print_on(outputStream* st) const {
913 Generation::print_on(st);
914 st->print(" eden");
915 eden()->print_on(st);
916 st->print(" from");
917 from()->print_on(st);
918 st->print(" to ");
919 to()->print_on(st);
920 }
921
922
923 const char* DefNewGeneration::name() const {
924 return "def new generation";
925 }
926
927 // Moved from inline file as they are not called inline
928 CompactibleSpace* DefNewGeneration::first_compaction_space() const {
929 return eden();
930 }
931
932 HeapWord* DefNewGeneration::allocate(size_t word_size,
933 bool is_tlab) {
934 // This is the slow-path allocation for the DefNewGeneration.
935 // Most allocations are fast-path in compiled code.
936 // We try to allocate from the eden. If that works, we are happy.
937 // Note that since DefNewGeneration supports lock-free allocation, we
938 // have to use it here, as well.
939 HeapWord* result = eden()->par_allocate(word_size);
940 if (result != NULL) {
941 return result;
942 }
943 do {
944 HeapWord* old_limit = eden()->soft_end();
945 if (old_limit < eden()->end()) {
946 // Tell the next generation we reached a limit.
947 HeapWord* new_limit =
948 next_gen()->allocation_limit_reached(eden(), eden()->top(), word_size);
949 if (new_limit != NULL) {
950 Atomic::cmpxchg_ptr(new_limit, eden()->soft_end_addr(), old_limit);
951 } else {
952 assert(eden()->soft_end() == eden()->end(),
953 "invalid state after allocation_limit_reached returned null");
954 }
955 } else {
956 // The allocation failed and the soft limit is equal to the hard limit,
957 // there are no reasons to do an attempt to allocate
958 assert(old_limit == eden()->end(), "sanity check");
959 break;
960 }
961 // Try to allocate until succeeded or the soft limit can't be adjusted
962 result = eden()->par_allocate(word_size);
963 } while (result == NULL);
964
965 // If the eden is full and the last collection bailed out, we are running
966 // out of heap space, and we try to allocate the from-space, too.
967 // allocate_from_space can't be inlined because that would introduce a
968 // circular dependency at compile time.
969 if (result == NULL) {
970 result = allocate_from_space(word_size);
971 }
972 return result;
973 }
974
975 HeapWord* DefNewGeneration::par_allocate(size_t word_size,
976 bool is_tlab) {
977 return eden()->par_allocate(word_size);
978 }
979
980 void DefNewGeneration::gc_prologue(bool full) {
981 // Ensure that _end and _soft_end are the same in eden space.
982 eden()->set_soft_end(eden()->end());
983 }
984
985 size_t DefNewGeneration::tlab_capacity() const {
986 return eden()->capacity();
987 }
988
989 size_t DefNewGeneration::unsafe_max_tlab_alloc() const {
990 return unsafe_max_alloc_nogc();
991 }