Mon, 26 Jan 2009 12:47:21 -0800
6786503: Overflow list performance can be improved
Summary: Avoid overflow list walk in CMS & ParNew when it is unnecessary. Fix a couple of correctness issues, including a C-heap leak, in ParNew at the intersection of promotion failure, work queue overflow and object array chunking. Add stress testing option and related assertion checking.
Reviewed-by: jmasa
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.
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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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 int i;
55 _n_gens = gen_policy()->number_of_generations();
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");
64 // The heap must be at least as aligned as generations.
65 size_t alignment = Generation::GenGrain;
67 _gen_specs = gen_policy()->generations();
68 PermanentGenerationSpec *perm_gen_spec =
69 collector_policy()->permanent_generation();
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);
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.
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 }
91 // Allocate space for the heap.
93 char* heap_address;
94 size_t total_reserved = 0;
95 int n_covered_regions = 0;
96 ReservedSpace heap_rs(0);
98 heap_address = allocate(alignment, perm_gen_spec, &total_reserved,
99 &n_covered_regions, &heap_rs);
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 }
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 }
119 _reserved = MemRegion((HeapWord*)heap_rs.base(),
120 (HeapWord*)(heap_rs.base() + heap_rs.size()));
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));
130 _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
131 set_barrier_set(rem_set()->bs());
132 _gch = this;
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());
142 clear_incremental_collection_will_fail();
143 clear_last_incremental_collection_failed();
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
154 return JNI_OK;
155 }
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";
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();
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");
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();
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();
192 total_reserved += s;
193 if (total_reserved < s) {
194 vm_exit_during_initialization(overflow_msg);
195 }
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 }
205 // Calculate the address at which the heap must reside in order for
206 // the shared data to be at the required address.
208 char* heap_address;
209 if (UseSharedSpaces) {
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;
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 }
223 *_total_reserved = total_reserved;
224 *_n_covered_regions = n_covered_regions;
225 *heap_rs = ReservedHeapSpace(total_reserved, alignment,
226 UseLargePages, heap_address);
228 return heap_address;
229 }
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");
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");
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 }
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 }
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 }
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 }
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 }
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 }
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 }
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 }
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
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 }
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 }
380 bool GenCollectedHeap::must_clear_all_soft_refs() {
381 return _gc_cause == GCCause::_last_ditch_collection;
382 }
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 }
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();)
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");
407 if (GC_locker::check_active_before_gc()) {
408 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
409 }
411 const size_t perm_prev_used = perm_gen()->used();
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 }
420 {
421 FlagSetting fl(_is_gc_active, true);
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);
437 gc_prologue(complete);
438 increment_total_collections(complete);
440 size_t gch_prev_used = used();
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 }
454 bool must_restore_marks_for_biased_locking = false;
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());
464 size_t prev_used = _gens[i]->used();
465 _gens[i]->stat_record()->invocations++;
466 _gens[i]->stat_record()->accumulated_time.start();
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();
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 }
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());
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 }
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
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 rp->setup_policy(clear_all_soft_refs);
529 } else {
530 // collect() below will enable discovery as appropriate
531 }
532 _gens[i]->collect(full, clear_all_soft_refs, size, is_tlab);
533 if (!rp->enqueuing_is_done()) {
534 rp->enqueue_discovered_references();
535 } else {
536 rp->set_enqueuing_is_done(false);
537 }
538 rp->verify_no_references_recorded();
539 }
540 max_level_collected = i;
542 // Determine if allocation request was met.
543 if (size > 0) {
544 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
545 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
546 size = 0;
547 }
548 }
549 }
551 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
553 _gens[i]->stat_record()->accumulated_time.stop();
555 update_gc_stats(i, full);
557 if (VerifyAfterGC && i >= VerifyGCLevel &&
558 total_collections() >= VerifyGCStartAt) {
559 HandleMark hm; // Discard invalid handles created during verification
560 gclog_or_tty->print(" VerifyAfterGC:");
561 Universe::verify(false);
562 }
564 if (PrintGCDetails) {
565 gclog_or_tty->print(":");
566 _gens[i]->print_heap_change(prev_used);
567 }
568 }
569 }
571 // Update "complete" boolean wrt what actually transpired --
572 // for instance, a promotion failure could have led to
573 // a whole heap collection.
574 complete = complete || (max_level_collected == n_gens() - 1);
576 if (PrintGCDetails) {
577 print_heap_change(gch_prev_used);
579 // Print perm gen info for full GC with PrintGCDetails flag.
580 if (complete) {
581 print_perm_heap_change(perm_prev_used);
582 }
583 }
585 for (int j = max_level_collected; j >= 0; j -= 1) {
586 // Adjust generation sizes.
587 _gens[j]->compute_new_size();
588 }
590 if (complete) {
591 // Ask the permanent generation to adjust size for full collections
592 perm()->compute_new_size();
593 update_full_collections_completed();
594 }
596 // Track memory usage and detect low memory after GC finishes
597 MemoryService::track_memory_usage();
599 gc_epilogue(complete);
601 if (must_restore_marks_for_biased_locking) {
602 BiasedLocking::restore_marks();
603 }
604 }
606 AdaptiveSizePolicy* sp = gen_policy()->size_policy();
607 AdaptiveSizePolicyOutput(sp, total_collections());
609 if (PrintHeapAtGC) {
610 Universe::print_heap_after_gc();
611 }
613 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
614 tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
615 vm_exit(-1);
616 }
617 }
619 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
620 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
621 }
623 void GenCollectedHeap::set_par_threads(int t) {
624 SharedHeap::set_par_threads(t);
625 _gen_process_strong_tasks->set_par_threads(t);
626 }
628 class AssertIsPermClosure: public OopClosure {
629 public:
630 void do_oop(oop* p) {
631 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
632 }
633 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
634 };
635 static AssertIsPermClosure assert_is_perm_closure;
637 void GenCollectedHeap::
638 gen_process_strong_roots(int level,
639 bool younger_gens_as_roots,
640 bool collecting_perm_gen,
641 SharedHeap::ScanningOption so,
642 OopsInGenClosure* older_gens,
643 OopsInGenClosure* not_older_gens) {
644 // General strong roots.
645 SharedHeap::process_strong_roots(collecting_perm_gen, so,
646 not_older_gens, older_gens);
648 if (younger_gens_as_roots) {
649 if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
650 for (int i = 0; i < level; i++) {
651 not_older_gens->set_generation(_gens[i]);
652 _gens[i]->oop_iterate(not_older_gens);
653 }
654 not_older_gens->reset_generation();
655 }
656 }
657 // When collection is parallel, all threads get to cooperate to do
658 // older-gen scanning.
659 for (int i = level+1; i < _n_gens; i++) {
660 older_gens->set_generation(_gens[i]);
661 rem_set()->younger_refs_iterate(_gens[i], older_gens);
662 older_gens->reset_generation();
663 }
665 _gen_process_strong_tasks->all_tasks_completed();
666 }
668 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
669 OopClosure* non_root_closure) {
670 SharedHeap::process_weak_roots(root_closure, non_root_closure);
671 // "Local" "weak" refs
672 for (int i = 0; i < _n_gens; i++) {
673 _gens[i]->ref_processor()->weak_oops_do(root_closure);
674 }
675 }
677 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
678 void GenCollectedHeap:: \
679 oop_since_save_marks_iterate(int level, \
680 OopClosureType* cur, \
681 OopClosureType* older) { \
682 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
683 for (int i = level+1; i < n_gens(); i++) { \
684 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
685 } \
686 perm_gen()->oop_since_save_marks_iterate##nv_suffix(older); \
687 }
689 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
691 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
693 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
694 for (int i = level; i < _n_gens; i++) {
695 if (!_gens[i]->no_allocs_since_save_marks()) return false;
696 }
697 return perm_gen()->no_allocs_since_save_marks();
698 }
700 bool GenCollectedHeap::supports_inline_contig_alloc() const {
701 return _gens[0]->supports_inline_contig_alloc();
702 }
704 HeapWord** GenCollectedHeap::top_addr() const {
705 return _gens[0]->top_addr();
706 }
708 HeapWord** GenCollectedHeap::end_addr() const {
709 return _gens[0]->end_addr();
710 }
712 size_t GenCollectedHeap::unsafe_max_alloc() {
713 return _gens[0]->unsafe_max_alloc_nogc();
714 }
716 // public collection interfaces
718 void GenCollectedHeap::collect(GCCause::Cause cause) {
719 if (should_do_concurrent_full_gc(cause)) {
720 #ifndef SERIALGC
721 // mostly concurrent full collection
722 collect_mostly_concurrent(cause);
723 #else // SERIALGC
724 ShouldNotReachHere();
725 #endif // SERIALGC
726 } else {
727 #ifdef ASSERT
728 if (cause == GCCause::_scavenge_alot) {
729 // minor collection only
730 collect(cause, 0);
731 } else {
732 // Stop-the-world full collection
733 collect(cause, n_gens() - 1);
734 }
735 #else
736 // Stop-the-world full collection
737 collect(cause, n_gens() - 1);
738 #endif
739 }
740 }
742 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
743 // The caller doesn't have the Heap_lock
744 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
745 MutexLocker ml(Heap_lock);
746 collect_locked(cause, max_level);
747 }
749 // This interface assumes that it's being called by the
750 // vm thread. It collects the heap assuming that the
751 // heap lock is already held and that we are executing in
752 // the context of the vm thread.
753 void GenCollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
754 assert(Thread::current()->is_VM_thread(), "Precondition#1");
755 assert(Heap_lock->is_locked(), "Precondition#2");
756 GCCauseSetter gcs(this, cause);
757 switch (cause) {
758 case GCCause::_heap_inspection:
759 case GCCause::_heap_dump: {
760 HandleMark hm;
761 do_full_collection(false, // don't clear all soft refs
762 n_gens() - 1);
763 break;
764 }
765 default: // XXX FIX ME
766 ShouldNotReachHere(); // Unexpected use of this function
767 }
768 }
770 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
771 // The caller has the Heap_lock
772 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
773 collect_locked(cause, n_gens() - 1);
774 }
776 // this is the private collection interface
777 // The Heap_lock is expected to be held on entry.
779 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
780 if (_preloading_shared_classes) {
781 warning("\nThe permanent generation is not large enough to preload "
782 "requested classes.\nUse -XX:PermSize= to increase the initial "
783 "size of the permanent generation.\n");
784 vm_exit(2);
785 }
786 // Read the GC count while holding the Heap_lock
787 unsigned int gc_count_before = total_collections();
788 unsigned int full_gc_count_before = total_full_collections();
789 {
790 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
791 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
792 cause, max_level);
793 VMThread::execute(&op);
794 }
795 }
797 #ifndef SERIALGC
798 bool GenCollectedHeap::create_cms_collector() {
800 assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
801 (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)) &&
802 _perm_gen->as_gen()->kind() == Generation::ConcurrentMarkSweep,
803 "Unexpected generation kinds");
804 // Skip two header words in the block content verification
805 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
806 CMSCollector* collector = new CMSCollector(
807 (ConcurrentMarkSweepGeneration*)_gens[1],
808 (ConcurrentMarkSweepGeneration*)_perm_gen->as_gen(),
809 _rem_set->as_CardTableRS(),
810 (ConcurrentMarkSweepPolicy*) collector_policy());
812 if (collector == NULL || !collector->completed_initialization()) {
813 if (collector) {
814 delete collector; // Be nice in embedded situation
815 }
816 vm_shutdown_during_initialization("Could not create CMS collector");
817 return false;
818 }
819 return true; // success
820 }
822 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
823 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
825 MutexLocker ml(Heap_lock);
826 // Read the GC counts while holding the Heap_lock
827 unsigned int full_gc_count_before = total_full_collections();
828 unsigned int gc_count_before = total_collections();
829 {
830 MutexUnlocker mu(Heap_lock);
831 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
832 VMThread::execute(&op);
833 }
834 }
835 #endif // SERIALGC
838 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
839 int max_level) {
840 int local_max_level;
841 if (!incremental_collection_will_fail() &&
842 gc_cause() == GCCause::_gc_locker) {
843 local_max_level = 0;
844 } else {
845 local_max_level = max_level;
846 }
848 do_collection(true /* full */,
849 clear_all_soft_refs /* clear_all_soft_refs */,
850 0 /* size */,
851 false /* is_tlab */,
852 local_max_level /* max_level */);
853 // Hack XXX FIX ME !!!
854 // A scavenge may not have been attempted, or may have
855 // been attempted and failed, because the old gen was too full
856 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
857 incremental_collection_will_fail()) {
858 if (PrintGCDetails) {
859 gclog_or_tty->print_cr("GC locker: Trying a full collection "
860 "because scavenge failed");
861 }
862 // This time allow the old gen to be collected as well
863 do_collection(true /* full */,
864 clear_all_soft_refs /* clear_all_soft_refs */,
865 0 /* size */,
866 false /* is_tlab */,
867 n_gens() - 1 /* max_level */);
868 }
869 }
871 // Returns "TRUE" iff "p" points into the allocated area of the heap.
872 bool GenCollectedHeap::is_in(const void* p) const {
873 #ifndef ASSERT
874 guarantee(VerifyBeforeGC ||
875 VerifyDuringGC ||
876 VerifyBeforeExit ||
877 VerifyAfterGC, "too expensive");
878 #endif
879 // This might be sped up with a cache of the last generation that
880 // answered yes.
881 for (int i = 0; i < _n_gens; i++) {
882 if (_gens[i]->is_in(p)) return true;
883 }
884 if (_perm_gen->as_gen()->is_in(p)) return true;
885 // Otherwise...
886 return false;
887 }
889 // Returns "TRUE" iff "p" points into the allocated area of the heap.
890 bool GenCollectedHeap::is_in_youngest(void* p) {
891 return _gens[0]->is_in(p);
892 }
894 void GenCollectedHeap::oop_iterate(OopClosure* cl) {
895 for (int i = 0; i < _n_gens; i++) {
896 _gens[i]->oop_iterate(cl);
897 }
898 }
900 void GenCollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl) {
901 for (int i = 0; i < _n_gens; i++) {
902 _gens[i]->oop_iterate(mr, cl);
903 }
904 }
906 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
907 for (int i = 0; i < _n_gens; i++) {
908 _gens[i]->object_iterate(cl);
909 }
910 perm_gen()->object_iterate(cl);
911 }
913 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
914 for (int i = 0; i < _n_gens; i++) {
915 _gens[i]->safe_object_iterate(cl);
916 }
917 perm_gen()->safe_object_iterate(cl);
918 }
920 void GenCollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
921 for (int i = 0; i < _n_gens; i++) {
922 _gens[i]->object_iterate_since_last_GC(cl);
923 }
924 }
926 Space* GenCollectedHeap::space_containing(const void* addr) const {
927 for (int i = 0; i < _n_gens; i++) {
928 Space* res = _gens[i]->space_containing(addr);
929 if (res != NULL) return res;
930 }
931 Space* res = perm_gen()->space_containing(addr);
932 if (res != NULL) return res;
933 // Otherwise...
934 assert(false, "Could not find containing space");
935 return NULL;
936 }
939 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
940 assert(is_in_reserved(addr), "block_start of address outside of heap");
941 for (int i = 0; i < _n_gens; i++) {
942 if (_gens[i]->is_in_reserved(addr)) {
943 assert(_gens[i]->is_in(addr),
944 "addr should be in allocated part of generation");
945 return _gens[i]->block_start(addr);
946 }
947 }
948 if (perm_gen()->is_in_reserved(addr)) {
949 assert(perm_gen()->is_in(addr),
950 "addr should be in allocated part of perm gen");
951 return perm_gen()->block_start(addr);
952 }
953 assert(false, "Some generation should contain the address");
954 return NULL;
955 }
957 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
958 assert(is_in_reserved(addr), "block_size of address outside of heap");
959 for (int i = 0; i < _n_gens; i++) {
960 if (_gens[i]->is_in_reserved(addr)) {
961 assert(_gens[i]->is_in(addr),
962 "addr should be in allocated part of generation");
963 return _gens[i]->block_size(addr);
964 }
965 }
966 if (perm_gen()->is_in_reserved(addr)) {
967 assert(perm_gen()->is_in(addr),
968 "addr should be in allocated part of perm gen");
969 return perm_gen()->block_size(addr);
970 }
971 assert(false, "Some generation should contain the address");
972 return 0;
973 }
975 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
976 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
977 assert(block_start(addr) == addr, "addr must be a block start");
978 for (int i = 0; i < _n_gens; i++) {
979 if (_gens[i]->is_in_reserved(addr)) {
980 return _gens[i]->block_is_obj(addr);
981 }
982 }
983 if (perm_gen()->is_in_reserved(addr)) {
984 return perm_gen()->block_is_obj(addr);
985 }
986 assert(false, "Some generation should contain the address");
987 return false;
988 }
990 bool GenCollectedHeap::supports_tlab_allocation() const {
991 for (int i = 0; i < _n_gens; i += 1) {
992 if (_gens[i]->supports_tlab_allocation()) {
993 return true;
994 }
995 }
996 return false;
997 }
999 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1000 size_t result = 0;
1001 for (int i = 0; i < _n_gens; i += 1) {
1002 if (_gens[i]->supports_tlab_allocation()) {
1003 result += _gens[i]->tlab_capacity();
1004 }
1005 }
1006 return result;
1007 }
1009 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1010 size_t result = 0;
1011 for (int i = 0; i < _n_gens; i += 1) {
1012 if (_gens[i]->supports_tlab_allocation()) {
1013 result += _gens[i]->unsafe_max_tlab_alloc();
1014 }
1015 }
1016 return result;
1017 }
1019 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1020 bool gc_overhead_limit_was_exceeded;
1021 HeapWord* result = mem_allocate(size /* size */,
1022 false /* is_large_noref */,
1023 true /* is_tlab */,
1024 &gc_overhead_limit_was_exceeded);
1025 return result;
1026 }
1028 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1029 // from the list headed by "*prev_ptr".
1030 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1031 bool first = true;
1032 size_t min_size = 0; // "first" makes this conceptually infinite.
1033 ScratchBlock **smallest_ptr, *smallest;
1034 ScratchBlock *cur = *prev_ptr;
1035 while (cur) {
1036 assert(*prev_ptr == cur, "just checking");
1037 if (first || cur->num_words < min_size) {
1038 smallest_ptr = prev_ptr;
1039 smallest = cur;
1040 min_size = smallest->num_words;
1041 first = false;
1042 }
1043 prev_ptr = &cur->next;
1044 cur = cur->next;
1045 }
1046 smallest = *smallest_ptr;
1047 *smallest_ptr = smallest->next;
1048 return smallest;
1049 }
1051 // Sort the scratch block list headed by res into decreasing size order,
1052 // and set "res" to the result.
1053 static void sort_scratch_list(ScratchBlock*& list) {
1054 ScratchBlock* sorted = NULL;
1055 ScratchBlock* unsorted = list;
1056 while (unsorted) {
1057 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1058 smallest->next = sorted;
1059 sorted = smallest;
1060 }
1061 list = sorted;
1062 }
1064 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1065 size_t max_alloc_words) {
1066 ScratchBlock* res = NULL;
1067 for (int i = 0; i < _n_gens; i++) {
1068 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1069 }
1070 sort_scratch_list(res);
1071 return res;
1072 }
1074 void GenCollectedHeap::release_scratch() {
1075 for (int i = 0; i < _n_gens; i++) {
1076 _gens[i]->reset_scratch();
1077 }
1078 }
1080 size_t GenCollectedHeap::large_typearray_limit() {
1081 return gen_policy()->large_typearray_limit();
1082 }
1084 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1085 void do_generation(Generation* gen) {
1086 gen->prepare_for_verify();
1087 }
1088 };
1090 void GenCollectedHeap::prepare_for_verify() {
1091 ensure_parsability(false); // no need to retire TLABs
1092 GenPrepareForVerifyClosure blk;
1093 generation_iterate(&blk, false);
1094 perm_gen()->prepare_for_verify();
1095 }
1098 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1099 bool old_to_young) {
1100 if (old_to_young) {
1101 for (int i = _n_gens-1; i >= 0; i--) {
1102 cl->do_generation(_gens[i]);
1103 }
1104 } else {
1105 for (int i = 0; i < _n_gens; i++) {
1106 cl->do_generation(_gens[i]);
1107 }
1108 }
1109 }
1111 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1112 for (int i = 0; i < _n_gens; i++) {
1113 _gens[i]->space_iterate(cl, true);
1114 }
1115 perm_gen()->space_iterate(cl, true);
1116 }
1118 bool GenCollectedHeap::is_maximal_no_gc() const {
1119 for (int i = 0; i < _n_gens; i++) { // skip perm gen
1120 if (!_gens[i]->is_maximal_no_gc()) {
1121 return false;
1122 }
1123 }
1124 return true;
1125 }
1127 void GenCollectedHeap::save_marks() {
1128 for (int i = 0; i < _n_gens; i++) {
1129 _gens[i]->save_marks();
1130 }
1131 perm_gen()->save_marks();
1132 }
1134 void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) {
1135 for (int i = 0; i <= collectedGen; i++) {
1136 _gens[i]->compute_new_size();
1137 }
1138 }
1140 GenCollectedHeap* GenCollectedHeap::heap() {
1141 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1142 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1143 return _gch;
1144 }
1147 void GenCollectedHeap::prepare_for_compaction() {
1148 Generation* scanning_gen = _gens[_n_gens-1];
1149 // Start by compacting into same gen.
1150 CompactPoint cp(scanning_gen, NULL, NULL);
1151 while (scanning_gen != NULL) {
1152 scanning_gen->prepare_for_compaction(&cp);
1153 scanning_gen = prev_gen(scanning_gen);
1154 }
1155 }
1157 GCStats* GenCollectedHeap::gc_stats(int level) const {
1158 return _gens[level]->gc_stats();
1159 }
1161 void GenCollectedHeap::verify(bool allow_dirty, bool silent) {
1162 if (!silent) {
1163 gclog_or_tty->print("permgen ");
1164 }
1165 perm_gen()->verify(allow_dirty);
1166 for (int i = _n_gens-1; i >= 0; i--) {
1167 Generation* g = _gens[i];
1168 if (!silent) {
1169 gclog_or_tty->print(g->name());
1170 gclog_or_tty->print(" ");
1171 }
1172 g->verify(allow_dirty);
1173 }
1174 if (!silent) {
1175 gclog_or_tty->print("remset ");
1176 }
1177 rem_set()->verify();
1178 if (!silent) {
1179 gclog_or_tty->print("ref_proc ");
1180 }
1181 ReferenceProcessor::verify();
1182 }
1184 void GenCollectedHeap::print() const { print_on(tty); }
1185 void GenCollectedHeap::print_on(outputStream* st) const {
1186 for (int i = 0; i < _n_gens; i++) {
1187 _gens[i]->print_on(st);
1188 }
1189 perm_gen()->print_on(st);
1190 }
1192 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1193 if (workers() != NULL) {
1194 workers()->threads_do(tc);
1195 }
1196 #ifndef SERIALGC
1197 if (UseConcMarkSweepGC) {
1198 ConcurrentMarkSweepThread::threads_do(tc);
1199 }
1200 #endif // SERIALGC
1201 }
1203 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1204 #ifndef SERIALGC
1205 if (UseParNewGC) {
1206 workers()->print_worker_threads_on(st);
1207 }
1208 if (UseConcMarkSweepGC) {
1209 ConcurrentMarkSweepThread::print_all_on(st);
1210 }
1211 #endif // SERIALGC
1212 }
1214 void GenCollectedHeap::print_tracing_info() const {
1215 if (TraceGen0Time) {
1216 get_gen(0)->print_summary_info();
1217 }
1218 if (TraceGen1Time) {
1219 get_gen(1)->print_summary_info();
1220 }
1221 }
1223 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1224 if (PrintGCDetails && Verbose) {
1225 gclog_or_tty->print(" " SIZE_FORMAT
1226 "->" SIZE_FORMAT
1227 "(" SIZE_FORMAT ")",
1228 prev_used, used(), capacity());
1229 } else {
1230 gclog_or_tty->print(" " SIZE_FORMAT "K"
1231 "->" SIZE_FORMAT "K"
1232 "(" SIZE_FORMAT "K)",
1233 prev_used / K, used() / K, capacity() / K);
1234 }
1235 }
1237 //New method to print perm gen info with PrintGCDetails flag
1238 void GenCollectedHeap::print_perm_heap_change(size_t perm_prev_used) const {
1239 gclog_or_tty->print(", [%s :", perm_gen()->short_name());
1240 perm_gen()->print_heap_change(perm_prev_used);
1241 gclog_or_tty->print("]");
1242 }
1244 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1245 private:
1246 bool _full;
1247 public:
1248 void do_generation(Generation* gen) {
1249 gen->gc_prologue(_full);
1250 }
1251 GenGCPrologueClosure(bool full) : _full(full) {};
1252 };
1254 void GenCollectedHeap::gc_prologue(bool full) {
1255 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1257 always_do_update_barrier = false;
1258 // Fill TLAB's and such
1259 CollectedHeap::accumulate_statistics_all_tlabs();
1260 ensure_parsability(true); // retire TLABs
1262 // Call allocation profiler
1263 AllocationProfiler::iterate_since_last_gc();
1264 // Walk generations
1265 GenGCPrologueClosure blk(full);
1266 generation_iterate(&blk, false); // not old-to-young.
1267 perm_gen()->gc_prologue(full);
1268 };
1270 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1271 private:
1272 bool _full;
1273 public:
1274 void do_generation(Generation* gen) {
1275 gen->gc_epilogue(_full);
1276 }
1277 GenGCEpilogueClosure(bool full) : _full(full) {};
1278 };
1280 void GenCollectedHeap::gc_epilogue(bool full) {
1281 // Remember if a partial collection of the heap failed, and
1282 // we did a complete collection.
1283 if (full && incremental_collection_will_fail()) {
1284 set_last_incremental_collection_failed();
1285 } else {
1286 clear_last_incremental_collection_failed();
1287 }
1288 // Clear the flag, if set; the generation gc_epilogues will set the
1289 // flag again if the condition persists despite the collection.
1290 clear_incremental_collection_will_fail();
1292 #ifdef COMPILER2
1293 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1294 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1295 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1296 #endif /* COMPILER2 */
1298 resize_all_tlabs();
1300 GenGCEpilogueClosure blk(full);
1301 generation_iterate(&blk, false); // not old-to-young.
1302 perm_gen()->gc_epilogue(full);
1304 always_do_update_barrier = UseConcMarkSweepGC;
1305 };
1307 #ifndef PRODUCT
1308 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1309 private:
1310 public:
1311 void do_generation(Generation* gen) {
1312 gen->record_spaces_top();
1313 }
1314 };
1316 void GenCollectedHeap::record_gen_tops_before_GC() {
1317 if (ZapUnusedHeapArea) {
1318 GenGCSaveTopsBeforeGCClosure blk;
1319 generation_iterate(&blk, false); // not old-to-young.
1320 perm_gen()->record_spaces_top();
1321 }
1322 }
1323 #endif // not PRODUCT
1325 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1326 public:
1327 void do_generation(Generation* gen) {
1328 gen->ensure_parsability();
1329 }
1330 };
1332 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1333 CollectedHeap::ensure_parsability(retire_tlabs);
1334 GenEnsureParsabilityClosure ep_cl;
1335 generation_iterate(&ep_cl, false);
1336 perm_gen()->ensure_parsability();
1337 }
1339 oop GenCollectedHeap::handle_failed_promotion(Generation* gen,
1340 oop obj,
1341 size_t obj_size) {
1342 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1343 HeapWord* result = NULL;
1345 // First give each higher generation a chance to allocate the promoted object.
1346 Generation* allocator = next_gen(gen);
1347 if (allocator != NULL) {
1348 do {
1349 result = allocator->allocate(obj_size, false);
1350 } while (result == NULL && (allocator = next_gen(allocator)) != NULL);
1351 }
1353 if (result == NULL) {
1354 // Then give gen and higher generations a chance to expand and allocate the
1355 // object.
1356 do {
1357 result = gen->expand_and_allocate(obj_size, false);
1358 } while (result == NULL && (gen = next_gen(gen)) != NULL);
1359 }
1361 if (result != NULL) {
1362 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1363 }
1364 return oop(result);
1365 }
1367 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1368 jlong _time; // in ms
1369 jlong _now; // in ms
1371 public:
1372 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1374 jlong time() { return _time; }
1376 void do_generation(Generation* gen) {
1377 _time = MIN2(_time, gen->time_of_last_gc(_now));
1378 }
1379 };
1381 jlong GenCollectedHeap::millis_since_last_gc() {
1382 jlong now = os::javaTimeMillis();
1383 GenTimeOfLastGCClosure tolgc_cl(now);
1384 // iterate over generations getting the oldest
1385 // time that a generation was collected
1386 generation_iterate(&tolgc_cl, false);
1387 tolgc_cl.do_generation(perm_gen());
1388 // XXX Despite the assert above, since javaTimeMillis()
1389 // doesnot guarantee monotonically increasing return
1390 // values (note, i didn't say "strictly monotonic"),
1391 // we need to guard against getting back a time
1392 // later than now. This should be fixed by basing
1393 // on someting like gethrtime() which guarantees
1394 // monotonicity. Note that cond_wait() is susceptible
1395 // to a similar problem, because its interface is
1396 // based on absolute time in the form of the
1397 // system time's notion of UCT. See also 4506635
1398 // for yet another problem of similar nature. XXX
1399 jlong retVal = now - tolgc_cl.time();
1400 if (retVal < 0) {
1401 NOT_PRODUCT(warning("time warp: %d", retVal);)
1402 return 0;
1403 }
1404 return retVal;
1405 }