Wed, 03 Mar 2010 14:48:26 -0800
4396719: Mark Sweep stack overflow on deeply nested Object arrays
Summary: Use an explicit stack for object arrays and process them in chunks.
Reviewed-by: iveresov, apetrusenko
1 /*
2 * Copyright 2000-2009 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.
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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
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23 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_genCollectedHeap.cpp.incl"
28 GenCollectedHeap* GenCollectedHeap::_gch;
29 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
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 };
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 }
53 jint GenCollectedHeap::initialize() {
54 CollectedHeap::pre_initialize();
56 int i;
57 _n_gens = gen_policy()->number_of_generations();
59 // While there are no constraints in the GC code that HeapWordSize
60 // be any particular value, there are multiple other areas in the
61 // system which believe this to be true (e.g. oop->object_size in some
62 // cases incorrectly returns the size in wordSize units rather than
63 // HeapWordSize).
64 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
66 // The heap must be at least as aligned as generations.
67 size_t alignment = Generation::GenGrain;
69 _gen_specs = gen_policy()->generations();
70 PermanentGenerationSpec *perm_gen_spec =
71 collector_policy()->permanent_generation();
73 // Make sure the sizes are all aligned.
74 for (i = 0; i < _n_gens; i++) {
75 _gen_specs[i]->align(alignment);
76 }
77 perm_gen_spec->align(alignment);
79 // If we are dumping the heap, then allocate a wasted block of address
80 // space in order to push the heap to a lower address. This extra
81 // address range allows for other (or larger) libraries to be loaded
82 // without them occupying the space required for the shared spaces.
84 if (DumpSharedSpaces) {
85 uintx reserved = 0;
86 uintx block_size = 64*1024*1024;
87 while (reserved < SharedDummyBlockSize) {
88 char* dummy = os::reserve_memory(block_size);
89 reserved += block_size;
90 }
91 }
93 // Allocate space for the heap.
95 char* heap_address;
96 size_t total_reserved = 0;
97 int n_covered_regions = 0;
98 ReservedSpace heap_rs(0);
100 heap_address = allocate(alignment, perm_gen_spec, &total_reserved,
101 &n_covered_regions, &heap_rs);
103 if (UseSharedSpaces) {
104 if (!heap_rs.is_reserved() || heap_address != heap_rs.base()) {
105 if (heap_rs.is_reserved()) {
106 heap_rs.release();
107 }
108 FileMapInfo* mapinfo = FileMapInfo::current_info();
109 mapinfo->fail_continue("Unable to reserve shared region.");
110 allocate(alignment, perm_gen_spec, &total_reserved, &n_covered_regions,
111 &heap_rs);
112 }
113 }
115 if (!heap_rs.is_reserved()) {
116 vm_shutdown_during_initialization(
117 "Could not reserve enough space for object heap");
118 return JNI_ENOMEM;
119 }
121 _reserved = MemRegion((HeapWord*)heap_rs.base(),
122 (HeapWord*)(heap_rs.base() + heap_rs.size()));
124 // It is important to do this in a way such that concurrent readers can't
125 // temporarily think somethings in the heap. (Seen this happen in asserts.)
126 _reserved.set_word_size(0);
127 _reserved.set_start((HeapWord*)heap_rs.base());
128 size_t actual_heap_size = heap_rs.size() - perm_gen_spec->misc_data_size()
129 - perm_gen_spec->misc_code_size();
130 _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
132 _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
133 set_barrier_set(rem_set()->bs());
135 _gch = this;
137 for (i = 0; i < _n_gens; i++) {
138 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(),
139 UseSharedSpaces, UseSharedSpaces);
140 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
141 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
142 }
143 _perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set());
145 clear_incremental_collection_will_fail();
146 clear_last_incremental_collection_failed();
148 #ifndef SERIALGC
149 // If we are running CMS, create the collector responsible
150 // for collecting the CMS generations.
151 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
152 bool success = create_cms_collector();
153 if (!success) return JNI_ENOMEM;
154 }
155 #endif // SERIALGC
157 return JNI_OK;
158 }
161 char* GenCollectedHeap::allocate(size_t alignment,
162 PermanentGenerationSpec* perm_gen_spec,
163 size_t* _total_reserved,
164 int* _n_covered_regions,
165 ReservedSpace* heap_rs){
166 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
167 "the maximum representable size";
169 // Now figure out the total size.
170 size_t total_reserved = 0;
171 int n_covered_regions = 0;
172 const size_t pageSize = UseLargePages ?
173 os::large_page_size() : os::vm_page_size();
175 for (int i = 0; i < _n_gens; i++) {
176 total_reserved += _gen_specs[i]->max_size();
177 if (total_reserved < _gen_specs[i]->max_size()) {
178 vm_exit_during_initialization(overflow_msg);
179 }
180 n_covered_regions += _gen_specs[i]->n_covered_regions();
181 }
182 assert(total_reserved % pageSize == 0, "Gen size");
183 total_reserved += perm_gen_spec->max_size();
184 assert(total_reserved % pageSize == 0, "Perm Gen size");
186 if (total_reserved < perm_gen_spec->max_size()) {
187 vm_exit_during_initialization(overflow_msg);
188 }
189 n_covered_regions += perm_gen_spec->n_covered_regions();
191 // Add the size of the data area which shares the same reserved area
192 // as the heap, but which is not actually part of the heap.
193 size_t s = perm_gen_spec->misc_data_size() + perm_gen_spec->misc_code_size();
195 total_reserved += s;
196 if (total_reserved < s) {
197 vm_exit_during_initialization(overflow_msg);
198 }
200 if (UseLargePages) {
201 assert(total_reserved != 0, "total_reserved cannot be 0");
202 total_reserved = round_to(total_reserved, os::large_page_size());
203 if (total_reserved < os::large_page_size()) {
204 vm_exit_during_initialization(overflow_msg);
205 }
206 }
208 // Calculate the address at which the heap must reside in order for
209 // the shared data to be at the required address.
211 char* heap_address;
212 if (UseSharedSpaces) {
214 // Calculate the address of the first word beyond the heap.
215 FileMapInfo* mapinfo = FileMapInfo::current_info();
216 int lr = CompactingPermGenGen::n_regions - 1;
217 size_t capacity = align_size_up(mapinfo->space_capacity(lr), alignment);
218 heap_address = mapinfo->region_base(lr) + capacity;
220 // Calculate the address of the first word of the heap.
221 heap_address -= total_reserved;
222 } else {
223 heap_address = NULL; // any address will do.
224 if (UseCompressedOops) {
225 heap_address = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
226 *_total_reserved = total_reserved;
227 *_n_covered_regions = n_covered_regions;
228 *heap_rs = ReservedHeapSpace(total_reserved, alignment,
229 UseLargePages, heap_address);
231 if (heap_address != NULL && !heap_rs->is_reserved()) {
232 // Failed to reserve at specified address - the requested memory
233 // region is taken already, for example, by 'java' launcher.
234 // Try again to reserver heap higher.
235 heap_address = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
236 *heap_rs = ReservedHeapSpace(total_reserved, alignment,
237 UseLargePages, heap_address);
239 if (heap_address != NULL && !heap_rs->is_reserved()) {
240 // Failed to reserve at specified address again - give up.
241 heap_address = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
242 assert(heap_address == NULL, "");
243 *heap_rs = ReservedHeapSpace(total_reserved, alignment,
244 UseLargePages, heap_address);
245 }
246 }
247 return heap_address;
248 }
249 }
251 *_total_reserved = total_reserved;
252 *_n_covered_regions = n_covered_regions;
253 *heap_rs = ReservedHeapSpace(total_reserved, alignment,
254 UseLargePages, heap_address);
256 return heap_address;
257 }
260 void GenCollectedHeap::post_initialize() {
261 SharedHeap::post_initialize();
262 TwoGenerationCollectorPolicy *policy =
263 (TwoGenerationCollectorPolicy *)collector_policy();
264 guarantee(policy->is_two_generation_policy(), "Illegal policy type");
265 DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
266 assert(def_new_gen->kind() == Generation::DefNew ||
267 def_new_gen->kind() == Generation::ParNew ||
268 def_new_gen->kind() == Generation::ASParNew,
269 "Wrong generation kind");
271 Generation* old_gen = get_gen(1);
272 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
273 old_gen->kind() == Generation::ASConcurrentMarkSweep ||
274 old_gen->kind() == Generation::MarkSweepCompact,
275 "Wrong generation kind");
277 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
278 old_gen->capacity(),
279 def_new_gen->from()->capacity());
280 policy->initialize_gc_policy_counters();
281 }
283 void GenCollectedHeap::ref_processing_init() {
284 SharedHeap::ref_processing_init();
285 for (int i = 0; i < _n_gens; i++) {
286 _gens[i]->ref_processor_init();
287 }
288 }
290 size_t GenCollectedHeap::capacity() const {
291 size_t res = 0;
292 for (int i = 0; i < _n_gens; i++) {
293 res += _gens[i]->capacity();
294 }
295 return res;
296 }
298 size_t GenCollectedHeap::used() const {
299 size_t res = 0;
300 for (int i = 0; i < _n_gens; i++) {
301 res += _gens[i]->used();
302 }
303 return res;
304 }
306 // Save the "used_region" for generations level and lower,
307 // and, if perm is true, for perm gen.
308 void GenCollectedHeap::save_used_regions(int level, bool perm) {
309 assert(level < _n_gens, "Illegal level parameter");
310 for (int i = level; i >= 0; i--) {
311 _gens[i]->save_used_region();
312 }
313 if (perm) {
314 perm_gen()->save_used_region();
315 }
316 }
318 size_t GenCollectedHeap::max_capacity() const {
319 size_t res = 0;
320 for (int i = 0; i < _n_gens; i++) {
321 res += _gens[i]->max_capacity();
322 }
323 return res;
324 }
326 // Update the _full_collections_completed counter
327 // at the end of a stop-world full GC.
328 unsigned int GenCollectedHeap::update_full_collections_completed() {
329 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
330 assert(_full_collections_completed <= _total_full_collections,
331 "Can't complete more collections than were started");
332 _full_collections_completed = _total_full_collections;
333 ml.notify_all();
334 return _full_collections_completed;
335 }
337 // Update the _full_collections_completed counter, as appropriate,
338 // at the end of a concurrent GC cycle. Note the conditional update
339 // below to allow this method to be called by a concurrent collector
340 // without synchronizing in any manner with the VM thread (which
341 // may already have initiated a STW full collection "concurrently").
342 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
343 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
344 assert((_full_collections_completed <= _total_full_collections) &&
345 (count <= _total_full_collections),
346 "Can't complete more collections than were started");
347 if (count > _full_collections_completed) {
348 _full_collections_completed = count;
349 ml.notify_all();
350 }
351 return _full_collections_completed;
352 }
355 #ifndef PRODUCT
356 // Override of memory state checking method in CollectedHeap:
357 // Some collectors (CMS for example) can't have badHeapWordVal written
358 // in the first two words of an object. (For instance , in the case of
359 // CMS these words hold state used to synchronize between certain
360 // (concurrent) GC steps and direct allocating mutators.)
361 // The skip_header_HeapWords() method below, allows us to skip
362 // over the requisite number of HeapWord's. Note that (for
363 // generational collectors) this means that those many words are
364 // skipped in each object, irrespective of the generation in which
365 // that object lives. The resultant loss of precision seems to be
366 // harmless and the pain of avoiding that imprecision appears somewhat
367 // higher than we are prepared to pay for such rudimentary debugging
368 // support.
369 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
370 size_t size) {
371 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
372 // We are asked to check a size in HeapWords,
373 // but the memory is mangled in juint words.
374 juint* start = (juint*) (addr + skip_header_HeapWords());
375 juint* end = (juint*) (addr + size);
376 for (juint* slot = start; slot < end; slot += 1) {
377 assert(*slot == badHeapWordVal,
378 "Found non badHeapWordValue in pre-allocation check");
379 }
380 }
381 }
382 #endif
384 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
385 bool is_tlab,
386 bool first_only) {
387 HeapWord* res;
388 for (int i = 0; i < _n_gens; i++) {
389 if (_gens[i]->should_allocate(size, is_tlab)) {
390 res = _gens[i]->allocate(size, is_tlab);
391 if (res != NULL) return res;
392 else if (first_only) break;
393 }
394 }
395 // Otherwise...
396 return NULL;
397 }
399 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
400 bool is_large_noref,
401 bool is_tlab,
402 bool* gc_overhead_limit_was_exceeded) {
403 return collector_policy()->mem_allocate_work(size,
404 is_tlab,
405 gc_overhead_limit_was_exceeded);
406 }
408 bool GenCollectedHeap::must_clear_all_soft_refs() {
409 return _gc_cause == GCCause::_last_ditch_collection;
410 }
412 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
413 return (cause == GCCause::_java_lang_system_gc ||
414 cause == GCCause::_gc_locker) &&
415 UseConcMarkSweepGC && ExplicitGCInvokesConcurrent;
416 }
418 void GenCollectedHeap::do_collection(bool full,
419 bool clear_all_soft_refs,
420 size_t size,
421 bool is_tlab,
422 int max_level) {
423 bool prepared_for_verification = false;
424 ResourceMark rm;
425 DEBUG_ONLY(Thread* my_thread = Thread::current();)
427 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
428 assert(my_thread->is_VM_thread() ||
429 my_thread->is_ConcurrentGC_thread(),
430 "incorrect thread type capability");
431 assert(Heap_lock->is_locked(), "the requesting thread should have the Heap_lock");
432 guarantee(!is_gc_active(), "collection is not reentrant");
433 assert(max_level < n_gens(), "sanity check");
435 if (GC_locker::check_active_before_gc()) {
436 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
437 }
439 const size_t perm_prev_used = perm_gen()->used();
441 if (PrintHeapAtGC) {
442 Universe::print_heap_before_gc();
443 if (Verbose) {
444 gclog_or_tty->print_cr("GC Cause: %s", GCCause::to_string(gc_cause()));
445 }
446 }
448 {
449 FlagSetting fl(_is_gc_active, true);
451 bool complete = full && (max_level == (n_gens()-1));
452 const char* gc_cause_str = "GC ";
453 if (complete) {
454 GCCause::Cause cause = gc_cause();
455 if (cause == GCCause::_java_lang_system_gc) {
456 gc_cause_str = "Full GC (System) ";
457 } else {
458 gc_cause_str = "Full GC ";
459 }
460 }
461 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
462 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
463 TraceTime t(gc_cause_str, PrintGCDetails, false, gclog_or_tty);
465 gc_prologue(complete);
466 increment_total_collections(complete);
468 size_t gch_prev_used = used();
470 int starting_level = 0;
471 if (full) {
472 // Search for the oldest generation which will collect all younger
473 // generations, and start collection loop there.
474 for (int i = max_level; i >= 0; i--) {
475 if (_gens[i]->full_collects_younger_generations()) {
476 starting_level = i;
477 break;
478 }
479 }
480 }
482 bool must_restore_marks_for_biased_locking = false;
484 int max_level_collected = starting_level;
485 for (int i = starting_level; i <= max_level; i++) {
486 if (_gens[i]->should_collect(full, size, is_tlab)) {
487 if (i == n_gens() - 1) { // a major collection is to happen
488 if (!complete) {
489 // The full_collections increment was missed above.
490 increment_total_full_collections();
491 }
492 pre_full_gc_dump(); // do any pre full gc dumps
493 }
494 // Timer for individual generations. Last argument is false: no CR
495 TraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, gclog_or_tty);
496 TraceCollectorStats tcs(_gens[i]->counters());
497 TraceMemoryManagerStats tmms(_gens[i]->kind());
499 size_t prev_used = _gens[i]->used();
500 _gens[i]->stat_record()->invocations++;
501 _gens[i]->stat_record()->accumulated_time.start();
503 // Must be done anew before each collection because
504 // a previous collection will do mangling and will
505 // change top of some spaces.
506 record_gen_tops_before_GC();
508 if (PrintGC && Verbose) {
509 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
510 i,
511 _gens[i]->stat_record()->invocations,
512 size*HeapWordSize);
513 }
515 if (VerifyBeforeGC && i >= VerifyGCLevel &&
516 total_collections() >= VerifyGCStartAt) {
517 HandleMark hm; // Discard invalid handles created during verification
518 if (!prepared_for_verification) {
519 prepare_for_verify();
520 prepared_for_verification = true;
521 }
522 gclog_or_tty->print(" VerifyBeforeGC:");
523 Universe::verify(true);
524 }
525 COMPILER2_PRESENT(DerivedPointerTable::clear());
527 if (!must_restore_marks_for_biased_locking &&
528 _gens[i]->performs_in_place_marking()) {
529 // We perform this mark word preservation work lazily
530 // because it's only at this point that we know whether we
531 // absolutely have to do it; we want to avoid doing it for
532 // scavenge-only collections where it's unnecessary
533 must_restore_marks_for_biased_locking = true;
534 BiasedLocking::preserve_marks();
535 }
537 // Do collection work
538 {
539 // Note on ref discovery: For what appear to be historical reasons,
540 // GCH enables and disabled (by enqueing) refs discovery.
541 // In the future this should be moved into the generation's
542 // collect method so that ref discovery and enqueueing concerns
543 // are local to a generation. The collect method could return
544 // an appropriate indication in the case that notification on
545 // the ref lock was needed. This will make the treatment of
546 // weak refs more uniform (and indeed remove such concerns
547 // from GCH). XXX
549 HandleMark hm; // Discard invalid handles created during gc
550 save_marks(); // save marks for all gens
551 // We want to discover references, but not process them yet.
552 // This mode is disabled in process_discovered_references if the
553 // generation does some collection work, or in
554 // enqueue_discovered_references if the generation returns
555 // without doing any work.
556 ReferenceProcessor* rp = _gens[i]->ref_processor();
557 // If the discovery of ("weak") refs in this generation is
558 // atomic wrt other collectors in this configuration, we
559 // are guaranteed to have empty discovered ref lists.
560 if (rp->discovery_is_atomic()) {
561 rp->verify_no_references_recorded();
562 rp->enable_discovery();
563 rp->setup_policy(clear_all_soft_refs);
564 } else {
565 // collect() below will enable discovery as appropriate
566 }
567 _gens[i]->collect(full, clear_all_soft_refs, size, is_tlab);
568 if (!rp->enqueuing_is_done()) {
569 rp->enqueue_discovered_references();
570 } else {
571 rp->set_enqueuing_is_done(false);
572 }
573 rp->verify_no_references_recorded();
574 }
575 max_level_collected = i;
577 // Determine if allocation request was met.
578 if (size > 0) {
579 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
580 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
581 size = 0;
582 }
583 }
584 }
586 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
588 _gens[i]->stat_record()->accumulated_time.stop();
590 update_gc_stats(i, full);
592 if (VerifyAfterGC && i >= VerifyGCLevel &&
593 total_collections() >= VerifyGCStartAt) {
594 HandleMark hm; // Discard invalid handles created during verification
595 gclog_or_tty->print(" VerifyAfterGC:");
596 Universe::verify(false);
597 }
599 if (PrintGCDetails) {
600 gclog_or_tty->print(":");
601 _gens[i]->print_heap_change(prev_used);
602 }
603 }
604 }
606 // Update "complete" boolean wrt what actually transpired --
607 // for instance, a promotion failure could have led to
608 // a whole heap collection.
609 complete = complete || (max_level_collected == n_gens() - 1);
611 if (complete) { // We did a "major" collection
612 post_full_gc_dump(); // do any post full gc dumps
613 }
615 if (PrintGCDetails) {
616 print_heap_change(gch_prev_used);
618 // Print perm gen info for full GC with PrintGCDetails flag.
619 if (complete) {
620 print_perm_heap_change(perm_prev_used);
621 }
622 }
624 for (int j = max_level_collected; j >= 0; j -= 1) {
625 // Adjust generation sizes.
626 _gens[j]->compute_new_size();
627 }
629 if (complete) {
630 // Ask the permanent generation to adjust size for full collections
631 perm()->compute_new_size();
632 update_full_collections_completed();
633 }
635 // Track memory usage and detect low memory after GC finishes
636 MemoryService::track_memory_usage();
638 gc_epilogue(complete);
640 if (must_restore_marks_for_biased_locking) {
641 BiasedLocking::restore_marks();
642 }
643 }
645 AdaptiveSizePolicy* sp = gen_policy()->size_policy();
646 AdaptiveSizePolicyOutput(sp, total_collections());
648 if (PrintHeapAtGC) {
649 Universe::print_heap_after_gc();
650 }
652 #ifdef TRACESPINNING
653 ParallelTaskTerminator::print_termination_counts();
654 #endif
656 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
657 tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
658 vm_exit(-1);
659 }
660 }
662 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
663 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
664 }
666 void GenCollectedHeap::set_par_threads(int t) {
667 SharedHeap::set_par_threads(t);
668 _gen_process_strong_tasks->set_par_threads(t);
669 }
671 class AssertIsPermClosure: public OopClosure {
672 public:
673 void do_oop(oop* p) {
674 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
675 }
676 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
677 };
678 static AssertIsPermClosure assert_is_perm_closure;
680 void GenCollectedHeap::
681 gen_process_strong_roots(int level,
682 bool younger_gens_as_roots,
683 bool activate_scope,
684 bool collecting_perm_gen,
685 SharedHeap::ScanningOption so,
686 OopsInGenClosure* not_older_gens,
687 bool do_code_roots,
688 OopsInGenClosure* older_gens) {
689 // General strong roots.
691 if (!do_code_roots) {
692 SharedHeap::process_strong_roots(activate_scope, collecting_perm_gen, so,
693 not_older_gens, NULL, older_gens);
694 } else {
695 bool do_code_marking = (activate_scope || nmethod::oops_do_marking_is_active());
696 CodeBlobToOopClosure code_roots(not_older_gens, /*do_marking=*/ do_code_marking);
697 SharedHeap::process_strong_roots(activate_scope, collecting_perm_gen, so,
698 not_older_gens, &code_roots, older_gens);
699 }
701 if (younger_gens_as_roots) {
702 if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
703 for (int i = 0; i < level; i++) {
704 not_older_gens->set_generation(_gens[i]);
705 _gens[i]->oop_iterate(not_older_gens);
706 }
707 not_older_gens->reset_generation();
708 }
709 }
710 // When collection is parallel, all threads get to cooperate to do
711 // older-gen scanning.
712 for (int i = level+1; i < _n_gens; i++) {
713 older_gens->set_generation(_gens[i]);
714 rem_set()->younger_refs_iterate(_gens[i], older_gens);
715 older_gens->reset_generation();
716 }
718 _gen_process_strong_tasks->all_tasks_completed();
719 }
721 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
722 CodeBlobClosure* code_roots,
723 OopClosure* non_root_closure) {
724 SharedHeap::process_weak_roots(root_closure, code_roots, non_root_closure);
725 // "Local" "weak" refs
726 for (int i = 0; i < _n_gens; i++) {
727 _gens[i]->ref_processor()->weak_oops_do(root_closure);
728 }
729 }
731 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
732 void GenCollectedHeap:: \
733 oop_since_save_marks_iterate(int level, \
734 OopClosureType* cur, \
735 OopClosureType* older) { \
736 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
737 for (int i = level+1; i < n_gens(); i++) { \
738 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
739 } \
740 perm_gen()->oop_since_save_marks_iterate##nv_suffix(older); \
741 }
743 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
745 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
747 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
748 for (int i = level; i < _n_gens; i++) {
749 if (!_gens[i]->no_allocs_since_save_marks()) return false;
750 }
751 return perm_gen()->no_allocs_since_save_marks();
752 }
754 bool GenCollectedHeap::supports_inline_contig_alloc() const {
755 return _gens[0]->supports_inline_contig_alloc();
756 }
758 HeapWord** GenCollectedHeap::top_addr() const {
759 return _gens[0]->top_addr();
760 }
762 HeapWord** GenCollectedHeap::end_addr() const {
763 return _gens[0]->end_addr();
764 }
766 size_t GenCollectedHeap::unsafe_max_alloc() {
767 return _gens[0]->unsafe_max_alloc_nogc();
768 }
770 // public collection interfaces
772 void GenCollectedHeap::collect(GCCause::Cause cause) {
773 if (should_do_concurrent_full_gc(cause)) {
774 #ifndef SERIALGC
775 // mostly concurrent full collection
776 collect_mostly_concurrent(cause);
777 #else // SERIALGC
778 ShouldNotReachHere();
779 #endif // SERIALGC
780 } else {
781 #ifdef ASSERT
782 if (cause == GCCause::_scavenge_alot) {
783 // minor collection only
784 collect(cause, 0);
785 } else {
786 // Stop-the-world full collection
787 collect(cause, n_gens() - 1);
788 }
789 #else
790 // Stop-the-world full collection
791 collect(cause, n_gens() - 1);
792 #endif
793 }
794 }
796 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
797 // The caller doesn't have the Heap_lock
798 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
799 MutexLocker ml(Heap_lock);
800 collect_locked(cause, max_level);
801 }
803 // This interface assumes that it's being called by the
804 // vm thread. It collects the heap assuming that the
805 // heap lock is already held and that we are executing in
806 // the context of the vm thread.
807 void GenCollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
808 assert(Thread::current()->is_VM_thread(), "Precondition#1");
809 assert(Heap_lock->is_locked(), "Precondition#2");
810 GCCauseSetter gcs(this, cause);
811 switch (cause) {
812 case GCCause::_heap_inspection:
813 case GCCause::_heap_dump: {
814 HandleMark hm;
815 do_full_collection(false, // don't clear all soft refs
816 n_gens() - 1);
817 break;
818 }
819 default: // XXX FIX ME
820 ShouldNotReachHere(); // Unexpected use of this function
821 }
822 }
824 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
825 // The caller has the Heap_lock
826 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
827 collect_locked(cause, n_gens() - 1);
828 }
830 // this is the private collection interface
831 // The Heap_lock is expected to be held on entry.
833 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
834 if (_preloading_shared_classes) {
835 warning("\nThe permanent generation is not large enough to preload "
836 "requested classes.\nUse -XX:PermSize= to increase the initial "
837 "size of the permanent generation.\n");
838 vm_exit(2);
839 }
840 // Read the GC count while holding the Heap_lock
841 unsigned int gc_count_before = total_collections();
842 unsigned int full_gc_count_before = total_full_collections();
843 {
844 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
845 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
846 cause, max_level);
847 VMThread::execute(&op);
848 }
849 }
851 #ifndef SERIALGC
852 bool GenCollectedHeap::create_cms_collector() {
854 assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
855 (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)) &&
856 _perm_gen->as_gen()->kind() == Generation::ConcurrentMarkSweep,
857 "Unexpected generation kinds");
858 // Skip two header words in the block content verification
859 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
860 CMSCollector* collector = new CMSCollector(
861 (ConcurrentMarkSweepGeneration*)_gens[1],
862 (ConcurrentMarkSweepGeneration*)_perm_gen->as_gen(),
863 _rem_set->as_CardTableRS(),
864 (ConcurrentMarkSweepPolicy*) collector_policy());
866 if (collector == NULL || !collector->completed_initialization()) {
867 if (collector) {
868 delete collector; // Be nice in embedded situation
869 }
870 vm_shutdown_during_initialization("Could not create CMS collector");
871 return false;
872 }
873 return true; // success
874 }
876 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
877 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
879 MutexLocker ml(Heap_lock);
880 // Read the GC counts while holding the Heap_lock
881 unsigned int full_gc_count_before = total_full_collections();
882 unsigned int gc_count_before = total_collections();
883 {
884 MutexUnlocker mu(Heap_lock);
885 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
886 VMThread::execute(&op);
887 }
888 }
889 #endif // SERIALGC
892 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
893 int max_level) {
894 int local_max_level;
895 if (!incremental_collection_will_fail() &&
896 gc_cause() == GCCause::_gc_locker) {
897 local_max_level = 0;
898 } else {
899 local_max_level = max_level;
900 }
902 do_collection(true /* full */,
903 clear_all_soft_refs /* clear_all_soft_refs */,
904 0 /* size */,
905 false /* is_tlab */,
906 local_max_level /* max_level */);
907 // Hack XXX FIX ME !!!
908 // A scavenge may not have been attempted, or may have
909 // been attempted and failed, because the old gen was too full
910 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
911 incremental_collection_will_fail()) {
912 if (PrintGCDetails) {
913 gclog_or_tty->print_cr("GC locker: Trying a full collection "
914 "because scavenge failed");
915 }
916 // This time allow the old gen to be collected as well
917 do_collection(true /* full */,
918 clear_all_soft_refs /* clear_all_soft_refs */,
919 0 /* size */,
920 false /* is_tlab */,
921 n_gens() - 1 /* max_level */);
922 }
923 }
925 // Returns "TRUE" iff "p" points into the allocated area of the heap.
926 bool GenCollectedHeap::is_in(const void* p) const {
927 #ifndef ASSERT
928 guarantee(VerifyBeforeGC ||
929 VerifyDuringGC ||
930 VerifyBeforeExit ||
931 PrintAssembly ||
932 tty->count() != 0 || // already printing
933 VerifyAfterGC, "too expensive");
934 #endif
935 // This might be sped up with a cache of the last generation that
936 // answered yes.
937 for (int i = 0; i < _n_gens; i++) {
938 if (_gens[i]->is_in(p)) return true;
939 }
940 if (_perm_gen->as_gen()->is_in(p)) return true;
941 // Otherwise...
942 return false;
943 }
945 // Returns "TRUE" iff "p" points into the allocated area of the heap.
946 bool GenCollectedHeap::is_in_youngest(void* p) {
947 return _gens[0]->is_in(p);
948 }
950 void GenCollectedHeap::oop_iterate(OopClosure* cl) {
951 for (int i = 0; i < _n_gens; i++) {
952 _gens[i]->oop_iterate(cl);
953 }
954 }
956 void GenCollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
957 for (int i = 0; i < _n_gens; i++) {
958 _gens[i]->oop_iterate(mr, cl);
959 }
960 }
962 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
963 for (int i = 0; i < _n_gens; i++) {
964 _gens[i]->object_iterate(cl);
965 }
966 perm_gen()->object_iterate(cl);
967 }
969 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
970 for (int i = 0; i < _n_gens; i++) {
971 _gens[i]->safe_object_iterate(cl);
972 }
973 perm_gen()->safe_object_iterate(cl);
974 }
976 void GenCollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
977 for (int i = 0; i < _n_gens; i++) {
978 _gens[i]->object_iterate_since_last_GC(cl);
979 }
980 }
982 Space* GenCollectedHeap::space_containing(const void* addr) const {
983 for (int i = 0; i < _n_gens; i++) {
984 Space* res = _gens[i]->space_containing(addr);
985 if (res != NULL) return res;
986 }
987 Space* res = perm_gen()->space_containing(addr);
988 if (res != NULL) return res;
989 // Otherwise...
990 assert(false, "Could not find containing space");
991 return NULL;
992 }
995 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
996 assert(is_in_reserved(addr), "block_start of address outside of heap");
997 for (int i = 0; i < _n_gens; i++) {
998 if (_gens[i]->is_in_reserved(addr)) {
999 assert(_gens[i]->is_in(addr),
1000 "addr should be in allocated part of generation");
1001 return _gens[i]->block_start(addr);
1002 }
1003 }
1004 if (perm_gen()->is_in_reserved(addr)) {
1005 assert(perm_gen()->is_in(addr),
1006 "addr should be in allocated part of perm gen");
1007 return perm_gen()->block_start(addr);
1008 }
1009 assert(false, "Some generation should contain the address");
1010 return NULL;
1011 }
1013 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1014 assert(is_in_reserved(addr), "block_size of address outside of heap");
1015 for (int i = 0; i < _n_gens; i++) {
1016 if (_gens[i]->is_in_reserved(addr)) {
1017 assert(_gens[i]->is_in(addr),
1018 "addr should be in allocated part of generation");
1019 return _gens[i]->block_size(addr);
1020 }
1021 }
1022 if (perm_gen()->is_in_reserved(addr)) {
1023 assert(perm_gen()->is_in(addr),
1024 "addr should be in allocated part of perm gen");
1025 return perm_gen()->block_size(addr);
1026 }
1027 assert(false, "Some generation should contain the address");
1028 return 0;
1029 }
1031 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1032 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1033 assert(block_start(addr) == addr, "addr must be a block start");
1034 for (int i = 0; i < _n_gens; i++) {
1035 if (_gens[i]->is_in_reserved(addr)) {
1036 return _gens[i]->block_is_obj(addr);
1037 }
1038 }
1039 if (perm_gen()->is_in_reserved(addr)) {
1040 return perm_gen()->block_is_obj(addr);
1041 }
1042 assert(false, "Some generation should contain the address");
1043 return false;
1044 }
1046 bool GenCollectedHeap::supports_tlab_allocation() const {
1047 for (int i = 0; i < _n_gens; i += 1) {
1048 if (_gens[i]->supports_tlab_allocation()) {
1049 return true;
1050 }
1051 }
1052 return false;
1053 }
1055 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1056 size_t result = 0;
1057 for (int i = 0; i < _n_gens; i += 1) {
1058 if (_gens[i]->supports_tlab_allocation()) {
1059 result += _gens[i]->tlab_capacity();
1060 }
1061 }
1062 return result;
1063 }
1065 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1066 size_t result = 0;
1067 for (int i = 0; i < _n_gens; i += 1) {
1068 if (_gens[i]->supports_tlab_allocation()) {
1069 result += _gens[i]->unsafe_max_tlab_alloc();
1070 }
1071 }
1072 return result;
1073 }
1075 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1076 bool gc_overhead_limit_was_exceeded;
1077 HeapWord* result = mem_allocate(size /* size */,
1078 false /* is_large_noref */,
1079 true /* is_tlab */,
1080 &gc_overhead_limit_was_exceeded);
1081 return result;
1082 }
1084 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1085 // from the list headed by "*prev_ptr".
1086 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1087 bool first = true;
1088 size_t min_size = 0; // "first" makes this conceptually infinite.
1089 ScratchBlock **smallest_ptr, *smallest;
1090 ScratchBlock *cur = *prev_ptr;
1091 while (cur) {
1092 assert(*prev_ptr == cur, "just checking");
1093 if (first || cur->num_words < min_size) {
1094 smallest_ptr = prev_ptr;
1095 smallest = cur;
1096 min_size = smallest->num_words;
1097 first = false;
1098 }
1099 prev_ptr = &cur->next;
1100 cur = cur->next;
1101 }
1102 smallest = *smallest_ptr;
1103 *smallest_ptr = smallest->next;
1104 return smallest;
1105 }
1107 // Sort the scratch block list headed by res into decreasing size order,
1108 // and set "res" to the result.
1109 static void sort_scratch_list(ScratchBlock*& list) {
1110 ScratchBlock* sorted = NULL;
1111 ScratchBlock* unsorted = list;
1112 while (unsorted) {
1113 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1114 smallest->next = sorted;
1115 sorted = smallest;
1116 }
1117 list = sorted;
1118 }
1120 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1121 size_t max_alloc_words) {
1122 ScratchBlock* res = NULL;
1123 for (int i = 0; i < _n_gens; i++) {
1124 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1125 }
1126 sort_scratch_list(res);
1127 return res;
1128 }
1130 void GenCollectedHeap::release_scratch() {
1131 for (int i = 0; i < _n_gens; i++) {
1132 _gens[i]->reset_scratch();
1133 }
1134 }
1136 size_t GenCollectedHeap::large_typearray_limit() {
1137 return gen_policy()->large_typearray_limit();
1138 }
1140 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1141 void do_generation(Generation* gen) {
1142 gen->prepare_for_verify();
1143 }
1144 };
1146 void GenCollectedHeap::prepare_for_verify() {
1147 ensure_parsability(false); // no need to retire TLABs
1148 GenPrepareForVerifyClosure blk;
1149 generation_iterate(&blk, false);
1150 perm_gen()->prepare_for_verify();
1151 }
1154 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1155 bool old_to_young) {
1156 if (old_to_young) {
1157 for (int i = _n_gens-1; i >= 0; i--) {
1158 cl->do_generation(_gens[i]);
1159 }
1160 } else {
1161 for (int i = 0; i < _n_gens; i++) {
1162 cl->do_generation(_gens[i]);
1163 }
1164 }
1165 }
1167 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1168 for (int i = 0; i < _n_gens; i++) {
1169 _gens[i]->space_iterate(cl, true);
1170 }
1171 perm_gen()->space_iterate(cl, true);
1172 }
1174 bool GenCollectedHeap::is_maximal_no_gc() const {
1175 for (int i = 0; i < _n_gens; i++) { // skip perm gen
1176 if (!_gens[i]->is_maximal_no_gc()) {
1177 return false;
1178 }
1179 }
1180 return true;
1181 }
1183 void GenCollectedHeap::save_marks() {
1184 for (int i = 0; i < _n_gens; i++) {
1185 _gens[i]->save_marks();
1186 }
1187 perm_gen()->save_marks();
1188 }
1190 void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) {
1191 for (int i = 0; i <= collectedGen; i++) {
1192 _gens[i]->compute_new_size();
1193 }
1194 }
1196 GenCollectedHeap* GenCollectedHeap::heap() {
1197 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1198 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1199 return _gch;
1200 }
1203 void GenCollectedHeap::prepare_for_compaction() {
1204 Generation* scanning_gen = _gens[_n_gens-1];
1205 // Start by compacting into same gen.
1206 CompactPoint cp(scanning_gen, NULL, NULL);
1207 while (scanning_gen != NULL) {
1208 scanning_gen->prepare_for_compaction(&cp);
1209 scanning_gen = prev_gen(scanning_gen);
1210 }
1211 }
1213 GCStats* GenCollectedHeap::gc_stats(int level) const {
1214 return _gens[level]->gc_stats();
1215 }
1217 void GenCollectedHeap::verify(bool allow_dirty, bool silent, bool option /* ignored */) {
1218 if (!silent) {
1219 gclog_or_tty->print("permgen ");
1220 }
1221 perm_gen()->verify(allow_dirty);
1222 for (int i = _n_gens-1; i >= 0; i--) {
1223 Generation* g = _gens[i];
1224 if (!silent) {
1225 gclog_or_tty->print(g->name());
1226 gclog_or_tty->print(" ");
1227 }
1228 g->verify(allow_dirty);
1229 }
1230 if (!silent) {
1231 gclog_or_tty->print("remset ");
1232 }
1233 rem_set()->verify();
1234 if (!silent) {
1235 gclog_or_tty->print("ref_proc ");
1236 }
1237 ReferenceProcessor::verify();
1238 }
1240 void GenCollectedHeap::print() const { print_on(tty); }
1241 void GenCollectedHeap::print_on(outputStream* st) const {
1242 for (int i = 0; i < _n_gens; i++) {
1243 _gens[i]->print_on(st);
1244 }
1245 perm_gen()->print_on(st);
1246 }
1248 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1249 if (workers() != NULL) {
1250 workers()->threads_do(tc);
1251 }
1252 #ifndef SERIALGC
1253 if (UseConcMarkSweepGC) {
1254 ConcurrentMarkSweepThread::threads_do(tc);
1255 }
1256 #endif // SERIALGC
1257 }
1259 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1260 #ifndef SERIALGC
1261 if (UseParNewGC) {
1262 workers()->print_worker_threads_on(st);
1263 }
1264 if (UseConcMarkSweepGC) {
1265 ConcurrentMarkSweepThread::print_all_on(st);
1266 }
1267 #endif // SERIALGC
1268 }
1270 void GenCollectedHeap::print_tracing_info() const {
1271 if (TraceGen0Time) {
1272 get_gen(0)->print_summary_info();
1273 }
1274 if (TraceGen1Time) {
1275 get_gen(1)->print_summary_info();
1276 }
1277 }
1279 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1280 if (PrintGCDetails && Verbose) {
1281 gclog_or_tty->print(" " SIZE_FORMAT
1282 "->" SIZE_FORMAT
1283 "(" SIZE_FORMAT ")",
1284 prev_used, used(), capacity());
1285 } else {
1286 gclog_or_tty->print(" " SIZE_FORMAT "K"
1287 "->" SIZE_FORMAT "K"
1288 "(" SIZE_FORMAT "K)",
1289 prev_used / K, used() / K, capacity() / K);
1290 }
1291 }
1293 //New method to print perm gen info with PrintGCDetails flag
1294 void GenCollectedHeap::print_perm_heap_change(size_t perm_prev_used) const {
1295 gclog_or_tty->print(", [%s :", perm_gen()->short_name());
1296 perm_gen()->print_heap_change(perm_prev_used);
1297 gclog_or_tty->print("]");
1298 }
1300 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1301 private:
1302 bool _full;
1303 public:
1304 void do_generation(Generation* gen) {
1305 gen->gc_prologue(_full);
1306 }
1307 GenGCPrologueClosure(bool full) : _full(full) {};
1308 };
1310 void GenCollectedHeap::gc_prologue(bool full) {
1311 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1313 always_do_update_barrier = false;
1314 // Fill TLAB's and such
1315 CollectedHeap::accumulate_statistics_all_tlabs();
1316 ensure_parsability(true); // retire TLABs
1318 // Call allocation profiler
1319 AllocationProfiler::iterate_since_last_gc();
1320 // Walk generations
1321 GenGCPrologueClosure blk(full);
1322 generation_iterate(&blk, false); // not old-to-young.
1323 perm_gen()->gc_prologue(full);
1324 };
1326 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1327 private:
1328 bool _full;
1329 public:
1330 void do_generation(Generation* gen) {
1331 gen->gc_epilogue(_full);
1332 }
1333 GenGCEpilogueClosure(bool full) : _full(full) {};
1334 };
1336 void GenCollectedHeap::gc_epilogue(bool full) {
1337 // Remember if a partial collection of the heap failed, and
1338 // we did a complete collection.
1339 if (full && incremental_collection_will_fail()) {
1340 set_last_incremental_collection_failed();
1341 } else {
1342 clear_last_incremental_collection_failed();
1343 }
1344 // Clear the flag, if set; the generation gc_epilogues will set the
1345 // flag again if the condition persists despite the collection.
1346 clear_incremental_collection_will_fail();
1348 #ifdef COMPILER2
1349 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1350 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1351 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1352 #endif /* COMPILER2 */
1354 resize_all_tlabs();
1356 GenGCEpilogueClosure blk(full);
1357 generation_iterate(&blk, false); // not old-to-young.
1358 perm_gen()->gc_epilogue(full);
1360 always_do_update_barrier = UseConcMarkSweepGC;
1361 };
1363 #ifndef PRODUCT
1364 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1365 private:
1366 public:
1367 void do_generation(Generation* gen) {
1368 gen->record_spaces_top();
1369 }
1370 };
1372 void GenCollectedHeap::record_gen_tops_before_GC() {
1373 if (ZapUnusedHeapArea) {
1374 GenGCSaveTopsBeforeGCClosure blk;
1375 generation_iterate(&blk, false); // not old-to-young.
1376 perm_gen()->record_spaces_top();
1377 }
1378 }
1379 #endif // not PRODUCT
1381 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1382 public:
1383 void do_generation(Generation* gen) {
1384 gen->ensure_parsability();
1385 }
1386 };
1388 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1389 CollectedHeap::ensure_parsability(retire_tlabs);
1390 GenEnsureParsabilityClosure ep_cl;
1391 generation_iterate(&ep_cl, false);
1392 perm_gen()->ensure_parsability();
1393 }
1395 oop GenCollectedHeap::handle_failed_promotion(Generation* gen,
1396 oop obj,
1397 size_t obj_size) {
1398 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1399 HeapWord* result = NULL;
1401 // First give each higher generation a chance to allocate the promoted object.
1402 Generation* allocator = next_gen(gen);
1403 if (allocator != NULL) {
1404 do {
1405 result = allocator->allocate(obj_size, false);
1406 } while (result == NULL && (allocator = next_gen(allocator)) != NULL);
1407 }
1409 if (result == NULL) {
1410 // Then give gen and higher generations a chance to expand and allocate the
1411 // object.
1412 do {
1413 result = gen->expand_and_allocate(obj_size, false);
1414 } while (result == NULL && (gen = next_gen(gen)) != NULL);
1415 }
1417 if (result != NULL) {
1418 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1419 }
1420 return oop(result);
1421 }
1423 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1424 jlong _time; // in ms
1425 jlong _now; // in ms
1427 public:
1428 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1430 jlong time() { return _time; }
1432 void do_generation(Generation* gen) {
1433 _time = MIN2(_time, gen->time_of_last_gc(_now));
1434 }
1435 };
1437 jlong GenCollectedHeap::millis_since_last_gc() {
1438 jlong now = os::javaTimeMillis();
1439 GenTimeOfLastGCClosure tolgc_cl(now);
1440 // iterate over generations getting the oldest
1441 // time that a generation was collected
1442 generation_iterate(&tolgc_cl, false);
1443 tolgc_cl.do_generation(perm_gen());
1444 // XXX Despite the assert above, since javaTimeMillis()
1445 // doesnot guarantee monotonically increasing return
1446 // values (note, i didn't say "strictly monotonic"),
1447 // we need to guard against getting back a time
1448 // later than now. This should be fixed by basing
1449 // on someting like gethrtime() which guarantees
1450 // monotonicity. Note that cond_wait() is susceptible
1451 // to a similar problem, because its interface is
1452 // based on absolute time in the form of the
1453 // system time's notion of UCT. See also 4506635
1454 // for yet another problem of similar nature. XXX
1455 jlong retVal = now - tolgc_cl.time();
1456 if (retVal < 0) {
1457 NOT_PRODUCT(warning("time warp: %d", retVal);)
1458 return 0;
1459 }
1460 return retVal;
1461 }