1 /*
2 * Copyright 2000-2008 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 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_genCollectedHeap.cpp.incl"
27
28 GenCollectedHeap* GenCollectedHeap::_gch;
29 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
30
31 // The set of potentially parallel tasks in strong root scanning.
32 enum GCH_process_strong_roots_tasks {
33 // We probably want to parallelize both of these internally, but for now...
34 GCH_PS_younger_gens,
35 // Leave this one last.
36 GCH_PS_NumElements
37 };
38
39 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
40 SharedHeap(policy),
41 _gen_policy(policy),
42 _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
43 _full_collections_completed(0)
44 {
45 if (_gen_process_strong_tasks == NULL ||
46 !_gen_process_strong_tasks->valid()) {
47 vm_exit_during_initialization("Failed necessary allocation.");
48 }
49 assert(policy != NULL, "Sanity check");
50 _preloading_shared_classes = false;
51 }
52
53 jint GenCollectedHeap::initialize() {
54 int i;
55 _n_gens = gen_policy()->number_of_generations();
56
57 // While there are no constraints in the GC code that HeapWordSize
58 // be any particular value, there are multiple other areas in the
59 // system which believe this to be true (e.g. oop->object_size in some
60 // cases incorrectly returns the size in wordSize units rather than
61 // HeapWordSize).
62 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
63
64 // The heap must be at least as aligned as generations.
65 size_t alignment = Generation::GenGrain;
66
67 _gen_specs = gen_policy()->generations();
68 PermanentGenerationSpec *perm_gen_spec =
69 collector_policy()->permanent_generation();
70
71 // Make sure the sizes are all aligned.
72 for (i = 0; i < _n_gens; i++) {
73 _gen_specs[i]->align(alignment);
74 }
75 perm_gen_spec->align(alignment);
76
77 // If we are dumping the heap, then allocate a wasted block of address
78 // space in order to push the heap to a lower address. This extra
79 // address range allows for other (or larger) libraries to be loaded
80 // without them occupying the space required for the shared spaces.
81
82 if (DumpSharedSpaces) {
83 uintx reserved = 0;
84 uintx block_size = 64*1024*1024;
85 while (reserved < SharedDummyBlockSize) {
86 char* dummy = os::reserve_memory(block_size);
87 reserved += block_size;
88 }
89 }
90
91 // Allocate space for the heap.
92
93 char* heap_address;
94 size_t total_reserved = 0;
95 int n_covered_regions = 0;
96 ReservedSpace heap_rs(0);
97
98 heap_address = allocate(alignment, perm_gen_spec, &total_reserved,
99 &n_covered_regions, &heap_rs);
100
101 if (UseSharedSpaces) {
102 if (!heap_rs.is_reserved() || heap_address != heap_rs.base()) {
103 if (heap_rs.is_reserved()) {
104 heap_rs.release();
105 }
106 FileMapInfo* mapinfo = FileMapInfo::current_info();
107 mapinfo->fail_continue("Unable to reserve shared region.");
108 allocate(alignment, perm_gen_spec, &total_reserved, &n_covered_regions,
109 &heap_rs);
110 }
111 }
112
113 if (!heap_rs.is_reserved()) {
114 vm_shutdown_during_initialization(
115 "Could not reserve enough space for object heap");
116 return JNI_ENOMEM;
117 }
118
119 _reserved = MemRegion((HeapWord*)heap_rs.base(),
120 (HeapWord*)(heap_rs.base() + heap_rs.size()));
121
122 // It is important to do this in a way such that concurrent readers can't
123 // temporarily think somethings in the heap. (Seen this happen in asserts.)
124 _reserved.set_word_size(0);
125 _reserved.set_start((HeapWord*)heap_rs.base());
126 size_t actual_heap_size = heap_rs.size() - perm_gen_spec->misc_data_size()
127 - perm_gen_spec->misc_code_size();
128 _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
129
130 _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
131 set_barrier_set(rem_set()->bs());
132 _gch = this;
133
134 for (i = 0; i < _n_gens; i++) {
135 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(),
136 UseSharedSpaces, UseSharedSpaces);
137 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
138 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
139 }
140 _perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set());
141
142 clear_incremental_collection_will_fail();
143 clear_last_incremental_collection_failed();
144
145 #ifndef SERIALGC
146 // If we are running CMS, create the collector responsible
147 // for collecting the CMS generations.
148 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
149 bool success = create_cms_collector();
150 if (!success) return JNI_ENOMEM;
151 }
152 #endif // SERIALGC
153
154 return JNI_OK;
155 }
156
157
158 char* GenCollectedHeap::allocate(size_t alignment,
159 PermanentGenerationSpec* perm_gen_spec,
160 size_t* _total_reserved,
161 int* _n_covered_regions,
162 ReservedSpace* heap_rs){
163 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
164 "the maximum representable size";
165
166 // Now figure out the total size.
167 size_t total_reserved = 0;
168 int n_covered_regions = 0;
169 const size_t pageSize = UseLargePages ?
170 os::large_page_size() : os::vm_page_size();
171
172 for (int i = 0; i < _n_gens; i++) {
173 total_reserved += _gen_specs[i]->max_size();
174 if (total_reserved < _gen_specs[i]->max_size()) {
175 vm_exit_during_initialization(overflow_msg);
176 }
177 n_covered_regions += _gen_specs[i]->n_covered_regions();
178 }
179 assert(total_reserved % pageSize == 0, "Gen size");
180 total_reserved += perm_gen_spec->max_size();
181 assert(total_reserved % pageSize == 0, "Perm Gen size");
182
183 if (total_reserved < perm_gen_spec->max_size()) {
184 vm_exit_during_initialization(overflow_msg);
185 }
186 n_covered_regions += perm_gen_spec->n_covered_regions();
187
188 // Add the size of the data area which shares the same reserved area
189 // as the heap, but which is not actually part of the heap.
190 size_t s = perm_gen_spec->misc_data_size() + perm_gen_spec->misc_code_size();
191
192 total_reserved += s;
193 if (total_reserved < s) {
194 vm_exit_during_initialization(overflow_msg);
195 }
196
197 if (UseLargePages) {
198 assert(total_reserved != 0, "total_reserved cannot be 0");
199 total_reserved = round_to(total_reserved, os::large_page_size());
200 if (total_reserved < os::large_page_size()) {
201 vm_exit_during_initialization(overflow_msg);
202 }
203 }
204
205 // Calculate the address at which the heap must reside in order for
206 // the shared data to be at the required address.
207
208 char* heap_address;
209 if (UseSharedSpaces) {
210
211 // Calculate the address of the first word beyond the heap.
212 FileMapInfo* mapinfo = FileMapInfo::current_info();
213 int lr = CompactingPermGenGen::n_regions - 1;
214 size_t capacity = align_size_up(mapinfo->space_capacity(lr), alignment);
215 heap_address = mapinfo->region_base(lr) + capacity;
216
217 // Calculate the address of the first word of the heap.
218 heap_address -= total_reserved;
219 } else {
220 heap_address = NULL; // any address will do.
221 }
222
223 *_total_reserved = total_reserved;
224 *_n_covered_regions = n_covered_regions;
225 *heap_rs = ReservedHeapSpace(total_reserved, alignment,
226 UseLargePages, heap_address);
227
228 return heap_address;
229 }
230
231
232 void GenCollectedHeap::post_initialize() {
233 SharedHeap::post_initialize();
234 TwoGenerationCollectorPolicy *policy =
235 (TwoGenerationCollectorPolicy *)collector_policy();
236 guarantee(policy->is_two_generation_policy(), "Illegal policy type");
237 DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
238 assert(def_new_gen->kind() == Generation::DefNew ||
239 def_new_gen->kind() == Generation::ParNew ||
240 def_new_gen->kind() == Generation::ASParNew,
241 "Wrong generation kind");
242
243 Generation* old_gen = get_gen(1);
244 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
245 old_gen->kind() == Generation::ASConcurrentMarkSweep ||
246 old_gen->kind() == Generation::MarkSweepCompact,
247 "Wrong generation kind");
248
249 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
250 old_gen->capacity(),
251 def_new_gen->from()->capacity());
252 policy->initialize_gc_policy_counters();
253 }
254
255 void GenCollectedHeap::ref_processing_init() {
256 SharedHeap::ref_processing_init();
257 for (int i = 0; i < _n_gens; i++) {
258 _gens[i]->ref_processor_init();
259 }
260 }
261
262 size_t GenCollectedHeap::capacity() const {
263 size_t res = 0;
264 for (int i = 0; i < _n_gens; i++) {
265 res += _gens[i]->capacity();
266 }
267 return res;
268 }
269
270 size_t GenCollectedHeap::used() const {
271 size_t res = 0;
272 for (int i = 0; i < _n_gens; i++) {
273 res += _gens[i]->used();
274 }
275 return res;
276 }
277
278 // Save the "used_region" for generations level and lower,
279 // and, if perm is true, for perm gen.
280 void GenCollectedHeap::save_used_regions(int level, bool perm) {
281 assert(level < _n_gens, "Illegal level parameter");
282 for (int i = level; i >= 0; i--) {
283 _gens[i]->save_used_region();
284 }
285 if (perm) {
286 perm_gen()->save_used_region();
287 }
288 }
289
290 size_t GenCollectedHeap::max_capacity() const {
291 size_t res = 0;
292 for (int i = 0; i < _n_gens; i++) {
293 res += _gens[i]->max_capacity();
294 }
295 return res;
296 }
297
298 // Update the _full_collections_completed counter
299 // at the end of a stop-world full GC.
300 unsigned int GenCollectedHeap::update_full_collections_completed() {
301 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
302 assert(_full_collections_completed <= _total_full_collections,
303 "Can't complete more collections than were started");
304 _full_collections_completed = _total_full_collections;
305 ml.notify_all();
306 return _full_collections_completed;
307 }
308
309 // Update the _full_collections_completed counter, as appropriate,
310 // at the end of a concurrent GC cycle. Note the conditional update
311 // below to allow this method to be called by a concurrent collector
312 // without synchronizing in any manner with the VM thread (which
313 // may already have initiated a STW full collection "concurrently").
314 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
315 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
316 assert((_full_collections_completed <= _total_full_collections) &&
317 (count <= _total_full_collections),
318 "Can't complete more collections than were started");
319 if (count > _full_collections_completed) {
320 _full_collections_completed = count;
321 ml.notify_all();
322 }
323 return _full_collections_completed;
324 }
325
326
327 #ifndef PRODUCT
328 // Override of memory state checking method in CollectedHeap:
329 // Some collectors (CMS for example) can't have badHeapWordVal written
330 // in the first two words of an object. (For instance , in the case of
331 // CMS these words hold state used to synchronize between certain
332 // (concurrent) GC steps and direct allocating mutators.)
333 // The skip_header_HeapWords() method below, allows us to skip
334 // over the requisite number of HeapWord's. Note that (for
335 // generational collectors) this means that those many words are
336 // skipped in each object, irrespective of the generation in which
337 // that object lives. The resultant loss of precision seems to be
338 // harmless and the pain of avoiding that imprecision appears somewhat
339 // higher than we are prepared to pay for such rudimentary debugging
340 // support.
341 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
342 size_t size) {
343 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
344 // We are asked to check a size in HeapWords,
345 // but the memory is mangled in juint words.
346 juint* start = (juint*) (addr + skip_header_HeapWords());
347 juint* end = (juint*) (addr + size);
348 for (juint* slot = start; slot < end; slot += 1) {
349 assert(*slot == badHeapWordVal,
350 "Found non badHeapWordValue in pre-allocation check");
351 }
352 }
353 }
354 #endif
355
356 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
357 bool is_tlab,
358 bool first_only) {
359 HeapWord* res;
360 for (int i = 0; i < _n_gens; i++) {
361 if (_gens[i]->should_allocate(size, is_tlab)) {
362 res = _gens[i]->allocate(size, is_tlab);
363 if (res != NULL) return res;
364 else if (first_only) break;
365 }
366 }
367 // Otherwise...
368 return NULL;
369 }
370
371 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
372 bool is_large_noref,
373 bool is_tlab,
374 bool* gc_overhead_limit_was_exceeded) {
375 return collector_policy()->mem_allocate_work(size,
376 is_tlab,
377 gc_overhead_limit_was_exceeded);
378 }
379
380 bool GenCollectedHeap::must_clear_all_soft_refs() {
381 return _gc_cause == GCCause::_last_ditch_collection;
382 }
383
384 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
385 return (cause == GCCause::_java_lang_system_gc ||
386 cause == GCCause::_gc_locker) &&
387 UseConcMarkSweepGC && ExplicitGCInvokesConcurrent;
388 }
389
390 void GenCollectedHeap::do_collection(bool full,
391 bool clear_all_soft_refs,
392 size_t size,
393 bool is_tlab,
394 int max_level) {
395 bool prepared_for_verification = false;
396 ResourceMark rm;
397 DEBUG_ONLY(Thread* my_thread = Thread::current();)
398
399 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
400 assert(my_thread->is_VM_thread() ||
401 my_thread->is_ConcurrentGC_thread(),
402 "incorrect thread type capability");
403 assert(Heap_lock->is_locked(), "the requesting thread should have the Heap_lock");
404 guarantee(!is_gc_active(), "collection is not reentrant");
405 assert(max_level < n_gens(), "sanity check");
406
407 if (GC_locker::check_active_before_gc()) {
408 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
409 }
410
411 const size_t perm_prev_used = perm_gen()->used();
412
413 if (PrintHeapAtGC) {
414 Universe::print_heap_before_gc();
415 if (Verbose) {
416 gclog_or_tty->print_cr("GC Cause: %s", GCCause::to_string(gc_cause()));
417 }
418 }
419
420 {
421 FlagSetting fl(_is_gc_active, true);
422
423 bool complete = full && (max_level == (n_gens()-1));
424 const char* gc_cause_str = "GC ";
425 if (complete) {
426 GCCause::Cause cause = gc_cause();
427 if (cause == GCCause::_java_lang_system_gc) {
428 gc_cause_str = "Full GC (System) ";
429 } else {
430 gc_cause_str = "Full GC ";
431 }
432 }
433 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
434 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
435 TraceTime t(gc_cause_str, PrintGCDetails, false, gclog_or_tty);
436
437 gc_prologue(complete);
438 increment_total_collections(complete);
439
440 size_t gch_prev_used = used();
441
442 int starting_level = 0;
443 if (full) {
444 // Search for the oldest generation which will collect all younger
445 // generations, and start collection loop there.
446 for (int i = max_level; i >= 0; i--) {
447 if (_gens[i]->full_collects_younger_generations()) {
448 starting_level = i;
449 break;
450 }
451 }
452 }
453
454 bool must_restore_marks_for_biased_locking = false;
455
456 int max_level_collected = starting_level;
457 for (int i = starting_level; i <= max_level; i++) {
458 if (_gens[i]->should_collect(full, size, is_tlab)) {
459 // Timer for individual generations. Last argument is false: no CR
460 TraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, gclog_or_tty);
461 TraceCollectorStats tcs(_gens[i]->counters());
462 TraceMemoryManagerStats tmms(_gens[i]->kind());
463
464 size_t prev_used = _gens[i]->used();
465 _gens[i]->stat_record()->invocations++;
466 _gens[i]->stat_record()->accumulated_time.start();
467
468 // Must be done anew before each collection because
469 // a previous collection will do mangling and will
470 // change top of some spaces.
471 record_gen_tops_before_GC();
472
473 if (PrintGC && Verbose) {
474 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
475 i,
476 _gens[i]->stat_record()->invocations,
477 size*HeapWordSize);
478 }
479
480 if (VerifyBeforeGC && i >= VerifyGCLevel &&
481 total_collections() >= VerifyGCStartAt) {
482 HandleMark hm; // Discard invalid handles created during verification
483 if (!prepared_for_verification) {
484 prepare_for_verify();
485 prepared_for_verification = true;
486 }
487 gclog_or_tty->print(" VerifyBeforeGC:");
488 Universe::verify(true);
489 }
490 COMPILER2_PRESENT(DerivedPointerTable::clear());
491
492 if (!must_restore_marks_for_biased_locking &&
493 _gens[i]->performs_in_place_marking()) {
494 // We perform this mark word preservation work lazily
495 // because it's only at this point that we know whether we
496 // absolutely have to do it; we want to avoid doing it for
497 // scavenge-only collections where it's unnecessary
498 must_restore_marks_for_biased_locking = true;
499 BiasedLocking::preserve_marks();
500 }
501
502 // Do collection work
503 {
504 // Note on ref discovery: For what appear to be historical reasons,
505 // GCH enables and disabled (by enqueing) refs discovery.
506 // In the future this should be moved into the generation's
507 // collect method so that ref discovery and enqueueing concerns
508 // are local to a generation. The collect method could return
509 // an appropriate indication in the case that notification on
510 // the ref lock was needed. This will make the treatment of
511 // weak refs more uniform (and indeed remove such concerns
512 // from GCH). XXX
513
514 HandleMark hm; // Discard invalid handles created during gc
515 save_marks(); // save marks for all gens
516 // We want to discover references, but not process them yet.
517 // This mode is disabled in process_discovered_references if the
518 // generation does some collection work, or in
519 // enqueue_discovered_references if the generation returns
520 // without doing any work.
521 ReferenceProcessor* rp = _gens[i]->ref_processor();
522 // If the discovery of ("weak") refs in this generation is
523 // atomic wrt other collectors in this configuration, we
524 // are guaranteed to have empty discovered ref lists.
525 if (rp->discovery_is_atomic()) {
526 rp->verify_no_references_recorded();
527 rp->enable_discovery();
528 } else {
529 // collect() will enable discovery as appropriate
530 }
531 _gens[i]->collect(full, clear_all_soft_refs, size, is_tlab);
532 if (!rp->enqueuing_is_done()) {
533 rp->enqueue_discovered_references();
534 } else {
535 rp->set_enqueuing_is_done(false);
536 }
537 rp->verify_no_references_recorded();
538 }
539 max_level_collected = i;
540
541 // Determine if allocation request was met.
542 if (size > 0) {
543 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
544 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
545 size = 0;
546 }
547 }
548 }
549
550 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
551
552 _gens[i]->stat_record()->accumulated_time.stop();
553
554 update_gc_stats(i, full);
555
556 if (VerifyAfterGC && i >= VerifyGCLevel &&
557 total_collections() >= VerifyGCStartAt) {
558 HandleMark hm; // Discard invalid handles created during verification
559 gclog_or_tty->print(" VerifyAfterGC:");
560 Universe::verify(false);
561 }
562
563 if (PrintGCDetails) {
564 gclog_or_tty->print(":");
565 _gens[i]->print_heap_change(prev_used);
566 }
567 }
568 }
569
570 // Update "complete" boolean wrt what actually transpired --
571 // for instance, a promotion failure could have led to
572 // a whole heap collection.
573 complete = complete || (max_level_collected == n_gens() - 1);
574
575 if (PrintGCDetails) {
576 print_heap_change(gch_prev_used);
577
578 // Print perm gen info for full GC with PrintGCDetails flag.
579 if (complete) {
580 print_perm_heap_change(perm_prev_used);
581 }
582 }
583
584 for (int j = max_level_collected; j >= 0; j -= 1) {
585 // Adjust generation sizes.
586 _gens[j]->compute_new_size();
587 }
588
589 if (complete) {
590 // Ask the permanent generation to adjust size for full collections
591 perm()->compute_new_size();
592 update_full_collections_completed();
593 }
594
595 // Track memory usage and detect low memory after GC finishes
596 MemoryService::track_memory_usage();
597
598 gc_epilogue(complete);
599
600 if (must_restore_marks_for_biased_locking) {
601 BiasedLocking::restore_marks();
602 }
603 }
604
605 AdaptiveSizePolicy* sp = gen_policy()->size_policy();
606 AdaptiveSizePolicyOutput(sp, total_collections());
607
608 if (PrintHeapAtGC) {
609 Universe::print_heap_after_gc();
610 }
611
612 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
613 tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
614 vm_exit(-1);
615 }
616 }
617
618 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
619 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
620 }
621
622 void GenCollectedHeap::set_par_threads(int t) {
623 SharedHeap::set_par_threads(t);
624 _gen_process_strong_tasks->set_par_threads(t);
625 }
626
627 class AssertIsPermClosure: public OopClosure {
628 public:
629 void do_oop(oop* p) {
630 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
631 }
632 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
633 };
634 static AssertIsPermClosure assert_is_perm_closure;
635
636 void GenCollectedHeap::
637 gen_process_strong_roots(int level,
638 bool younger_gens_as_roots,
639 bool collecting_perm_gen,
640 SharedHeap::ScanningOption so,
641 OopsInGenClosure* older_gens,
642 OopsInGenClosure* not_older_gens) {
643 // General strong roots.
644 SharedHeap::process_strong_roots(collecting_perm_gen, so,
645 not_older_gens, older_gens);
646
647 if (younger_gens_as_roots) {
648 if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
649 for (int i = 0; i < level; i++) {
650 not_older_gens->set_generation(_gens[i]);
651 _gens[i]->oop_iterate(not_older_gens);
652 }
653 not_older_gens->reset_generation();
654 }
655 }
656 // When collection is parallel, all threads get to cooperate to do
657 // older-gen scanning.
658 for (int i = level+1; i < _n_gens; i++) {
659 older_gens->set_generation(_gens[i]);
660 rem_set()->younger_refs_iterate(_gens[i], older_gens);
661 older_gens->reset_generation();
662 }
663
664 _gen_process_strong_tasks->all_tasks_completed();
665 }
666
667 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
668 OopClosure* non_root_closure) {
669 SharedHeap::process_weak_roots(root_closure, non_root_closure);
670 // "Local" "weak" refs
671 for (int i = 0; i < _n_gens; i++) {
672 _gens[i]->ref_processor()->weak_oops_do(root_closure);
673 }
674 }
675
676 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
677 void GenCollectedHeap:: \
678 oop_since_save_marks_iterate(int level, \
679 OopClosureType* cur, \
680 OopClosureType* older) { \
681 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
682 for (int i = level+1; i < n_gens(); i++) { \
683 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
684 } \
685 perm_gen()->oop_since_save_marks_iterate##nv_suffix(older); \
686 }
687
688 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
689
690 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
691
692 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
693 for (int i = level; i < _n_gens; i++) {
694 if (!_gens[i]->no_allocs_since_save_marks()) return false;
695 }
696 return perm_gen()->no_allocs_since_save_marks();
697 }
698
699 bool GenCollectedHeap::supports_inline_contig_alloc() const {
700 return _gens[0]->supports_inline_contig_alloc();
701 }
702
703 HeapWord** GenCollectedHeap::top_addr() const {
704 return _gens[0]->top_addr();
705 }
706
707 HeapWord** GenCollectedHeap::end_addr() const {
708 return _gens[0]->end_addr();
709 }
710
711 size_t GenCollectedHeap::unsafe_max_alloc() {
712 return _gens[0]->unsafe_max_alloc_nogc();
713 }
714
715 // public collection interfaces
716
717 void GenCollectedHeap::collect(GCCause::Cause cause) {
718 if (should_do_concurrent_full_gc(cause)) {
719 #ifndef SERIALGC
720 // mostly concurrent full collection
721 collect_mostly_concurrent(cause);
722 #else // SERIALGC
723 ShouldNotReachHere();
724 #endif // SERIALGC
725 } else {
726 #ifdef ASSERT
727 if (cause == GCCause::_scavenge_alot) {
728 // minor collection only
729 collect(cause, 0);
730 } else {
731 // Stop-the-world full collection
732 collect(cause, n_gens() - 1);
733 }
734 #else
735 // Stop-the-world full collection
736 collect(cause, n_gens() - 1);
737 #endif
738 }
739 }
740
741 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
742 // The caller doesn't have the Heap_lock
743 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
744 MutexLocker ml(Heap_lock);
745 collect_locked(cause, max_level);
746 }
747
748 // This interface assumes that it's being called by the
749 // vm thread. It collects the heap assuming that the
750 // heap lock is already held and that we are executing in
751 // the context of the vm thread.
752 void GenCollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
753 assert(Thread::current()->is_VM_thread(), "Precondition#1");
754 assert(Heap_lock->is_locked(), "Precondition#2");
755 GCCauseSetter gcs(this, cause);
756 switch (cause) {
757 case GCCause::_heap_inspection:
758 case GCCause::_heap_dump: {
759 HandleMark hm;
760 do_full_collection(false, // don't clear all soft refs
761 n_gens() - 1);
762 break;
763 }
764 default: // XXX FIX ME
765 ShouldNotReachHere(); // Unexpected use of this function
766 }
767 }
768
769 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
770 // The caller has the Heap_lock
771 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
772 collect_locked(cause, n_gens() - 1);
773 }
774
775 // this is the private collection interface
776 // The Heap_lock is expected to be held on entry.
777
778 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
779 if (_preloading_shared_classes) {
780 warning("\nThe permanent generation is not large enough to preload "
781 "requested classes.\nUse -XX:PermSize= to increase the initial "
782 "size of the permanent generation.\n");
783 vm_exit(2);
784 }
785 // Read the GC count while holding the Heap_lock
786 unsigned int gc_count_before = total_collections();
787 unsigned int full_gc_count_before = total_full_collections();
788 {
789 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
790 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
791 cause, max_level);
792 VMThread::execute(&op);
793 }
794 }
795
796 #ifndef SERIALGC
797 bool GenCollectedHeap::create_cms_collector() {
798
799 assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
800 (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)) &&
801 _perm_gen->as_gen()->kind() == Generation::ConcurrentMarkSweep,
802 "Unexpected generation kinds");
803 // Skip two header words in the block content verification
804 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
805 CMSCollector* collector = new CMSCollector(
806 (ConcurrentMarkSweepGeneration*)_gens[1],
807 (ConcurrentMarkSweepGeneration*)_perm_gen->as_gen(),
808 _rem_set->as_CardTableRS(),
809 (ConcurrentMarkSweepPolicy*) collector_policy());
810
811 if (collector == NULL || !collector->completed_initialization()) {
812 if (collector) {
813 delete collector; // Be nice in embedded situation
814 }
815 vm_shutdown_during_initialization("Could not create CMS collector");
816 return false;
817 }
818 return true; // success
819 }
820
821 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
822 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
823
824 MutexLocker ml(Heap_lock);
825 // Read the GC counts while holding the Heap_lock
826 unsigned int full_gc_count_before = total_full_collections();
827 unsigned int gc_count_before = total_collections();
828 {
829 MutexUnlocker mu(Heap_lock);
830 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
831 VMThread::execute(&op);
832 }
833 }
834 #endif // SERIALGC
835
836
837 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
838 int max_level) {
839 int local_max_level;
840 if (!incremental_collection_will_fail() &&
841 gc_cause() == GCCause::_gc_locker) {
842 local_max_level = 0;
843 } else {
844 local_max_level = max_level;
845 }
846
847 do_collection(true /* full */,
848 clear_all_soft_refs /* clear_all_soft_refs */,
849 0 /* size */,
850 false /* is_tlab */,
851 local_max_level /* max_level */);
852 // Hack XXX FIX ME !!!
853 // A scavenge may not have been attempted, or may have
854 // been attempted and failed, because the old gen was too full
855 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
856 incremental_collection_will_fail()) {
857 if (PrintGCDetails) {
858 gclog_or_tty->print_cr("GC locker: Trying a full collection "
859 "because scavenge failed");
860 }
861 // This time allow the old gen to be collected as well
862 do_collection(true /* full */,
863 clear_all_soft_refs /* clear_all_soft_refs */,
864 0 /* size */,
865 false /* is_tlab */,
866 n_gens() - 1 /* max_level */);
867 }
868 }
869
870 // Returns "TRUE" iff "p" points into the allocated area of the heap.
871 bool GenCollectedHeap::is_in(const void* p) const {
872 #ifndef ASSERT
873 guarantee(VerifyBeforeGC ||
874 VerifyDuringGC ||
875 VerifyBeforeExit ||
876 VerifyAfterGC, "too expensive");
877 #endif
878 // This might be sped up with a cache of the last generation that
879 // answered yes.
880 for (int i = 0; i < _n_gens; i++) {
881 if (_gens[i]->is_in(p)) return true;
882 }
883 if (_perm_gen->as_gen()->is_in(p)) return true;
884 // Otherwise...
885 return false;
886 }
887
888 // Returns "TRUE" iff "p" points into the allocated area of the heap.
889 bool GenCollectedHeap::is_in_youngest(void* p) {
890 return _gens[0]->is_in(p);
891 }
892
893 void GenCollectedHeap::oop_iterate(OopClosure* cl) {
894 for (int i = 0; i < _n_gens; i++) {
895 _gens[i]->oop_iterate(cl);
896 }
897 }
898
899 void GenCollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
900 for (int i = 0; i < _n_gens; i++) {
901 _gens[i]->oop_iterate(mr, cl);
902 }
903 }
904
905 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
906 for (int i = 0; i < _n_gens; i++) {
907 _gens[i]->object_iterate(cl);
908 }
909 perm_gen()->object_iterate(cl);
910 }
911
912 void GenCollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
913 for (int i = 0; i < _n_gens; i++) {
914 _gens[i]->object_iterate_since_last_GC(cl);
915 }
916 }
917
918 Space* GenCollectedHeap::space_containing(const void* addr) const {
919 for (int i = 0; i < _n_gens; i++) {
920 Space* res = _gens[i]->space_containing(addr);
921 if (res != NULL) return res;
922 }
923 Space* res = perm_gen()->space_containing(addr);
924 if (res != NULL) return res;
925 // Otherwise...
926 assert(false, "Could not find containing space");
927 return NULL;
928 }
929
930
931 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
932 assert(is_in_reserved(addr), "block_start of address outside of heap");
933 for (int i = 0; i < _n_gens; i++) {
934 if (_gens[i]->is_in_reserved(addr)) {
935 assert(_gens[i]->is_in(addr),
936 "addr should be in allocated part of generation");
937 return _gens[i]->block_start(addr);
938 }
939 }
940 if (perm_gen()->is_in_reserved(addr)) {
941 assert(perm_gen()->is_in(addr),
942 "addr should be in allocated part of perm gen");
943 return perm_gen()->block_start(addr);
944 }
945 assert(false, "Some generation should contain the address");
946 return NULL;
947 }
948
949 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
950 assert(is_in_reserved(addr), "block_size of address outside of heap");
951 for (int i = 0; i < _n_gens; i++) {
952 if (_gens[i]->is_in_reserved(addr)) {
953 assert(_gens[i]->is_in(addr),
954 "addr should be in allocated part of generation");
955 return _gens[i]->block_size(addr);
956 }
957 }
958 if (perm_gen()->is_in_reserved(addr)) {
959 assert(perm_gen()->is_in(addr),
960 "addr should be in allocated part of perm gen");
961 return perm_gen()->block_size(addr);
962 }
963 assert(false, "Some generation should contain the address");
964 return 0;
965 }
966
967 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
968 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
969 assert(block_start(addr) == addr, "addr must be a block start");
970 for (int i = 0; i < _n_gens; i++) {
971 if (_gens[i]->is_in_reserved(addr)) {
972 return _gens[i]->block_is_obj(addr);
973 }
974 }
975 if (perm_gen()->is_in_reserved(addr)) {
976 return perm_gen()->block_is_obj(addr);
977 }
978 assert(false, "Some generation should contain the address");
979 return false;
980 }
981
982 bool GenCollectedHeap::supports_tlab_allocation() const {
983 for (int i = 0; i < _n_gens; i += 1) {
984 if (_gens[i]->supports_tlab_allocation()) {
985 return true;
986 }
987 }
988 return false;
989 }
990
991 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
992 size_t result = 0;
993 for (int i = 0; i < _n_gens; i += 1) {
994 if (_gens[i]->supports_tlab_allocation()) {
995 result += _gens[i]->tlab_capacity();
996 }
997 }
998 return result;
999 }
1000
1001 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1002 size_t result = 0;
1003 for (int i = 0; i < _n_gens; i += 1) {
1004 if (_gens[i]->supports_tlab_allocation()) {
1005 result += _gens[i]->unsafe_max_tlab_alloc();
1006 }
1007 }
1008 return result;
1009 }
1010
1011 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1012 bool gc_overhead_limit_was_exceeded;
1013 HeapWord* result = mem_allocate(size /* size */,
1014 false /* is_large_noref */,
1015 true /* is_tlab */,
1016 &gc_overhead_limit_was_exceeded);
1017 return result;
1018 }
1019
1020 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1021 // from the list headed by "*prev_ptr".
1022 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1023 bool first = true;
1024 size_t min_size = 0; // "first" makes this conceptually infinite.
1025 ScratchBlock **smallest_ptr, *smallest;
1026 ScratchBlock *cur = *prev_ptr;
1027 while (cur) {
1028 assert(*prev_ptr == cur, "just checking");
1029 if (first || cur->num_words < min_size) {
1030 smallest_ptr = prev_ptr;
1031 smallest = cur;
1032 min_size = smallest->num_words;
1033 first = false;
1034 }
1035 prev_ptr = &cur->next;
1036 cur = cur->next;
1037 }
1038 smallest = *smallest_ptr;
1039 *smallest_ptr = smallest->next;
1040 return smallest;
1041 }
1042
1043 // Sort the scratch block list headed by res into decreasing size order,
1044 // and set "res" to the result.
1045 static void sort_scratch_list(ScratchBlock*& list) {
1046 ScratchBlock* sorted = NULL;
1047 ScratchBlock* unsorted = list;
1048 while (unsorted) {
1049 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1050 smallest->next = sorted;
1051 sorted = smallest;
1052 }
1053 list = sorted;
1054 }
1055
1056 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1057 size_t max_alloc_words) {
1058 ScratchBlock* res = NULL;
1059 for (int i = 0; i < _n_gens; i++) {
1060 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1061 }
1062 sort_scratch_list(res);
1063 return res;
1064 }
1065
1066 void GenCollectedHeap::release_scratch() {
1067 for (int i = 0; i < _n_gens; i++) {
1068 _gens[i]->reset_scratch();
1069 }
1070 }
1071
1072 size_t GenCollectedHeap::large_typearray_limit() {
1073 return gen_policy()->large_typearray_limit();
1074 }
1075
1076 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1077 void do_generation(Generation* gen) {
1078 gen->prepare_for_verify();
1079 }
1080 };
1081
1082 void GenCollectedHeap::prepare_for_verify() {
1083 ensure_parsability(false); // no need to retire TLABs
1084 GenPrepareForVerifyClosure blk;
1085 generation_iterate(&blk, false);
1086 perm_gen()->prepare_for_verify();
1087 }
1088
1089
1090 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1091 bool old_to_young) {
1092 if (old_to_young) {
1093 for (int i = _n_gens-1; i >= 0; i--) {
1094 cl->do_generation(_gens[i]);
1095 }
1096 } else {
1097 for (int i = 0; i < _n_gens; i++) {
1098 cl->do_generation(_gens[i]);
1099 }
1100 }
1101 }
1102
1103 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1104 for (int i = 0; i < _n_gens; i++) {
1105 _gens[i]->space_iterate(cl, true);
1106 }
1107 perm_gen()->space_iterate(cl, true);
1108 }
1109
1110 bool GenCollectedHeap::is_maximal_no_gc() const {
1111 for (int i = 0; i < _n_gens; i++) { // skip perm gen
1112 if (!_gens[i]->is_maximal_no_gc()) {
1113 return false;
1114 }
1115 }
1116 return true;
1117 }
1118
1119 void GenCollectedHeap::save_marks() {
1120 for (int i = 0; i < _n_gens; i++) {
1121 _gens[i]->save_marks();
1122 }
1123 perm_gen()->save_marks();
1124 }
1125
1126 void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) {
1127 for (int i = 0; i <= collectedGen; i++) {
1128 _gens[i]->compute_new_size();
1129 }
1130 }
1131
1132 GenCollectedHeap* GenCollectedHeap::heap() {
1133 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1134 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1135 return _gch;
1136 }
1137
1138
1139 void GenCollectedHeap::prepare_for_compaction() {
1140 Generation* scanning_gen = _gens[_n_gens-1];
1141 // Start by compacting into same gen.
1142 CompactPoint cp(scanning_gen, NULL, NULL);
1143 while (scanning_gen != NULL) {
1144 scanning_gen->prepare_for_compaction(&cp);
1145 scanning_gen = prev_gen(scanning_gen);
1146 }
1147 }
1148
1149 GCStats* GenCollectedHeap::gc_stats(int level) const {
1150 return _gens[level]->gc_stats();
1151 }
1152
1153 void GenCollectedHeap::verify(bool allow_dirty, bool silent) {
1154 if (!silent) {
1155 gclog_or_tty->print("permgen ");
1156 }
1157 perm_gen()->verify(allow_dirty);
1158 for (int i = _n_gens-1; i >= 0; i--) {
1159 Generation* g = _gens[i];
1160 if (!silent) {
1161 gclog_or_tty->print(g->name());
1162 gclog_or_tty->print(" ");
1163 }
1164 g->verify(allow_dirty);
1165 }
1166 if (!silent) {
1167 gclog_or_tty->print("remset ");
1168 }
1169 rem_set()->verify();
1170 if (!silent) {
1171 gclog_or_tty->print("ref_proc ");
1172 }
1173 ReferenceProcessor::verify();
1174 }
1175
1176 void GenCollectedHeap::print() const { print_on(tty); }
1177 void GenCollectedHeap::print_on(outputStream* st) const {
1178 for (int i = 0; i < _n_gens; i++) {
1179 _gens[i]->print_on(st);
1180 }
1181 perm_gen()->print_on(st);
1182 }
1183
1184 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1185 if (workers() != NULL) {
1186 workers()->threads_do(tc);
1187 }
1188 #ifndef SERIALGC
1189 if (UseConcMarkSweepGC) {
1190 ConcurrentMarkSweepThread::threads_do(tc);
1191 }
1192 #endif // SERIALGC
1193 }
1194
1195 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1196 #ifndef SERIALGC
1197 if (UseParNewGC) {
1198 workers()->print_worker_threads_on(st);
1199 }
1200 if (UseConcMarkSweepGC) {
1201 ConcurrentMarkSweepThread::print_all_on(st);
1202 }
1203 #endif // SERIALGC
1204 }
1205
1206 void GenCollectedHeap::print_tracing_info() const {
1207 if (TraceGen0Time) {
1208 get_gen(0)->print_summary_info();
1209 }
1210 if (TraceGen1Time) {
1211 get_gen(1)->print_summary_info();
1212 }
1213 }
1214
1215 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1216 if (PrintGCDetails && Verbose) {
1217 gclog_or_tty->print(" " SIZE_FORMAT
1218 "->" SIZE_FORMAT
1219 "(" SIZE_FORMAT ")",
1220 prev_used, used(), capacity());
1221 } else {
1222 gclog_or_tty->print(" " SIZE_FORMAT "K"
1223 "->" SIZE_FORMAT "K"
1224 "(" SIZE_FORMAT "K)",
1225 prev_used / K, used() / K, capacity() / K);
1226 }
1227 }
1228
1229 //New method to print perm gen info with PrintGCDetails flag
1230 void GenCollectedHeap::print_perm_heap_change(size_t perm_prev_used) const {
1231 gclog_or_tty->print(", [%s :", perm_gen()->short_name());
1232 perm_gen()->print_heap_change(perm_prev_used);
1233 gclog_or_tty->print("]");
1234 }
1235
1236 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1237 private:
1238 bool _full;
1239 public:
1240 void do_generation(Generation* gen) {
1241 gen->gc_prologue(_full);
1242 }
1243 GenGCPrologueClosure(bool full) : _full(full) {};
1244 };
1245
1246 void GenCollectedHeap::gc_prologue(bool full) {
1247 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1248
1249 always_do_update_barrier = false;
1250 // Fill TLAB's and such
1251 CollectedHeap::accumulate_statistics_all_tlabs();
1252 ensure_parsability(true); // retire TLABs
1253
1254 // Call allocation profiler
1255 AllocationProfiler::iterate_since_last_gc();
1256 // Walk generations
1257 GenGCPrologueClosure blk(full);
1258 generation_iterate(&blk, false); // not old-to-young.
1259 perm_gen()->gc_prologue(full);
1260 };
1261
1262 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1263 private:
1264 bool _full;
1265 public:
1266 void do_generation(Generation* gen) {
1267 gen->gc_epilogue(_full);
1268 }
1269 GenGCEpilogueClosure(bool full) : _full(full) {};
1270 };
1271
1272 void GenCollectedHeap::gc_epilogue(bool full) {
1273 // Remember if a partial collection of the heap failed, and
1274 // we did a complete collection.
1275 if (full && incremental_collection_will_fail()) {
1276 set_last_incremental_collection_failed();
1277 } else {
1278 clear_last_incremental_collection_failed();
1279 }
1280 // Clear the flag, if set; the generation gc_epilogues will set the
1281 // flag again if the condition persists despite the collection.
1282 clear_incremental_collection_will_fail();
1283
1284 #ifdef COMPILER2
1285 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1286 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1287 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1288 #endif /* COMPILER2 */
1289
1290 resize_all_tlabs();
1291
1292 GenGCEpilogueClosure blk(full);
1293 generation_iterate(&blk, false); // not old-to-young.
1294 perm_gen()->gc_epilogue(full);
1295
1296 always_do_update_barrier = UseConcMarkSweepGC;
1297 };
1298
1299 #ifndef PRODUCT
1300 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1301 private:
1302 public:
1303 void do_generation(Generation* gen) {
1304 gen->record_spaces_top();
1305 }
1306 };
1307
1308 void GenCollectedHeap::record_gen_tops_before_GC() {
1309 if (ZapUnusedHeapArea) {
1310 GenGCSaveTopsBeforeGCClosure blk;
1311 generation_iterate(&blk, false); // not old-to-young.
1312 perm_gen()->record_spaces_top();
1313 }
1314 }
1315 #endif // not PRODUCT
1316
1317 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1318 public:
1319 void do_generation(Generation* gen) {
1320 gen->ensure_parsability();
1321 }
1322 };
1323
1324 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1325 CollectedHeap::ensure_parsability(retire_tlabs);
1326 GenEnsureParsabilityClosure ep_cl;
1327 generation_iterate(&ep_cl, false);
1328 perm_gen()->ensure_parsability();
1329 }
1330
1331 oop GenCollectedHeap::handle_failed_promotion(Generation* gen,
1332 oop obj,
1333 size_t obj_size) {
1334 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1335 HeapWord* result = NULL;
1336
1337 // First give each higher generation a chance to allocate the promoted object.
1338 Generation* allocator = next_gen(gen);
1339 if (allocator != NULL) {
1340 do {
1341 result = allocator->allocate(obj_size, false);
1342 } while (result == NULL && (allocator = next_gen(allocator)) != NULL);
1343 }
1344
1345 if (result == NULL) {
1346 // Then give gen and higher generations a chance to expand and allocate the
1347 // object.
1348 do {
1349 result = gen->expand_and_allocate(obj_size, false);
1350 } while (result == NULL && (gen = next_gen(gen)) != NULL);
1351 }
1352
1353 if (result != NULL) {
1354 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1355 }
1356 return oop(result);
1357 }
1358
1359 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1360 jlong _time; // in ms
1361 jlong _now; // in ms
1362
1363 public:
1364 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1365
1366 jlong time() { return _time; }
1367
1368 void do_generation(Generation* gen) {
1369 _time = MIN2(_time, gen->time_of_last_gc(_now));
1370 }
1371 };
1372
1373 jlong GenCollectedHeap::millis_since_last_gc() {
1374 jlong now = os::javaTimeMillis();
1375 GenTimeOfLastGCClosure tolgc_cl(now);
1376 // iterate over generations getting the oldest
1377 // time that a generation was collected
1378 generation_iterate(&tolgc_cl, false);
1379 tolgc_cl.do_generation(perm_gen());
1380 // XXX Despite the assert above, since javaTimeMillis()
1381 // doesnot guarantee monotonically increasing return
1382 // values (note, i didn't say "strictly monotonic"),
1383 // we need to guard against getting back a time
1384 // later than now. This should be fixed by basing
1385 // on someting like gethrtime() which guarantees
1386 // monotonicity. Note that cond_wait() is susceptible
1387 // to a similar problem, because its interface is
1388 // based on absolute time in the form of the
1389 // system time's notion of UCT. See also 4506635
1390 // for yet another problem of similar nature. XXX
1391 jlong retVal = now - tolgc_cl.time();
1392 if (retVal < 0) {
1393 NOT_PRODUCT(warning("time warp: %d", retVal);)
1394 return 0;
1395 }
1396 return retVal;
1397 }