Mon, 07 Jul 2014 10:12:40 +0200
8049421: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
Contributed-by: stefan.karlsson@oracle.com, mikael.gerdin@oracle.com
1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
25 #include "precompiled.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
30 #include "gc_implementation/g1/heapRegion.inline.hpp"
31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
33 #include "gc_implementation/shared/liveRange.hpp"
34 #include "memory/genOopClosures.inline.hpp"
35 #include "memory/iterator.hpp"
36 #include "memory/space.inline.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/orderAccess.inline.hpp"
40 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
42 int HeapRegion::LogOfHRGrainBytes = 0;
43 int HeapRegion::LogOfHRGrainWords = 0;
44 size_t HeapRegion::GrainBytes = 0;
45 size_t HeapRegion::GrainWords = 0;
46 size_t HeapRegion::CardsPerRegion = 0;
48 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
49 HeapRegion* hr, ExtendedOopClosure* cl,
50 CardTableModRefBS::PrecisionStyle precision,
51 FilterKind fk) :
52 DirtyCardToOopClosure(hr, cl, precision, NULL),
53 _hr(hr), _fk(fk), _g1(g1) { }
55 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
56 OopClosure* oc) :
57 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
59 template<class ClosureType>
60 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
61 HeapRegion* hr,
62 HeapWord* cur, HeapWord* top) {
63 oop cur_oop = oop(cur);
64 size_t oop_size = hr->block_size(cur);
65 HeapWord* next_obj = cur + oop_size;
66 while (next_obj < top) {
67 // Keep filtering the remembered set.
68 if (!g1h->is_obj_dead(cur_oop, hr)) {
69 // Bottom lies entirely below top, so we can call the
70 // non-memRegion version of oop_iterate below.
71 cur_oop->oop_iterate(cl);
72 }
73 cur = next_obj;
74 cur_oop = oop(cur);
75 oop_size = hr->block_size(cur);
76 next_obj = cur + oop_size;
77 }
78 return cur;
79 }
81 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
82 HeapWord* bottom,
83 HeapWord* top) {
84 G1CollectedHeap* g1h = _g1;
85 size_t oop_size;
86 ExtendedOopClosure* cl2 = NULL;
88 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
89 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
91 switch (_fk) {
92 case NoFilterKind: cl2 = _cl; break;
93 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
94 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
95 default: ShouldNotReachHere();
96 }
98 // Start filtering what we add to the remembered set. If the object is
99 // not considered dead, either because it is marked (in the mark bitmap)
100 // or it was allocated after marking finished, then we add it. Otherwise
101 // we can safely ignore the object.
102 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
103 oop_size = oop(bottom)->oop_iterate(cl2, mr);
104 } else {
105 oop_size = _hr->block_size(bottom);
106 }
108 bottom += oop_size;
110 if (bottom < top) {
111 // We replicate the loop below for several kinds of possible filters.
112 switch (_fk) {
113 case NoFilterKind:
114 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
115 break;
117 case IntoCSFilterKind: {
118 FilterIntoCSClosure filt(this, g1h, _cl);
119 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
120 break;
121 }
123 case OutOfRegionFilterKind: {
124 FilterOutOfRegionClosure filt(_hr, _cl);
125 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
126 break;
127 }
129 default:
130 ShouldNotReachHere();
131 }
133 // Last object. Need to do dead-obj filtering here too.
134 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
135 oop(bottom)->oop_iterate(cl2, mr);
136 }
137 }
138 }
140 // Minimum region size; we won't go lower than that.
141 // We might want to decrease this in the future, to deal with small
142 // heaps a bit more efficiently.
143 #define MIN_REGION_SIZE ( 1024 * 1024 )
145 // Maximum region size; we don't go higher than that. There's a good
146 // reason for having an upper bound. We don't want regions to get too
147 // large, otherwise cleanup's effectiveness would decrease as there
148 // will be fewer opportunities to find totally empty regions after
149 // marking.
150 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
152 // The automatic region size calculation will try to have around this
153 // many regions in the heap (based on the min heap size).
154 #define TARGET_REGION_NUMBER 2048
156 size_t HeapRegion::max_region_size() {
157 return (size_t)MAX_REGION_SIZE;
158 }
160 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
161 uintx region_size = G1HeapRegionSize;
162 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
163 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
164 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
165 (uintx) MIN_REGION_SIZE);
166 }
168 int region_size_log = log2_long((jlong) region_size);
169 // Recalculate the region size to make sure it's a power of
170 // 2. This means that region_size is the largest power of 2 that's
171 // <= what we've calculated so far.
172 region_size = ((uintx)1 << region_size_log);
174 // Now make sure that we don't go over or under our limits.
175 if (region_size < MIN_REGION_SIZE) {
176 region_size = MIN_REGION_SIZE;
177 } else if (region_size > MAX_REGION_SIZE) {
178 region_size = MAX_REGION_SIZE;
179 }
181 // And recalculate the log.
182 region_size_log = log2_long((jlong) region_size);
184 // Now, set up the globals.
185 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
186 LogOfHRGrainBytes = region_size_log;
188 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
189 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
191 guarantee(GrainBytes == 0, "we should only set it once");
192 // The cast to int is safe, given that we've bounded region_size by
193 // MIN_REGION_SIZE and MAX_REGION_SIZE.
194 GrainBytes = (size_t)region_size;
196 guarantee(GrainWords == 0, "we should only set it once");
197 GrainWords = GrainBytes >> LogHeapWordSize;
198 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
200 guarantee(CardsPerRegion == 0, "we should only set it once");
201 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
202 }
204 void HeapRegion::reset_after_compaction() {
205 G1OffsetTableContigSpace::reset_after_compaction();
206 // After a compaction the mark bitmap is invalid, so we must
207 // treat all objects as being inside the unmarked area.
208 zero_marked_bytes();
209 init_top_at_mark_start();
210 }
212 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
213 assert(_humongous_type == NotHumongous,
214 "we should have already filtered out humongous regions");
215 assert(_humongous_start_region == NULL,
216 "we should have already filtered out humongous regions");
217 assert(_end == _orig_end,
218 "we should have already filtered out humongous regions");
220 _in_collection_set = false;
222 set_young_index_in_cset(-1);
223 uninstall_surv_rate_group();
224 set_young_type(NotYoung);
225 reset_pre_dummy_top();
227 if (!par) {
228 // If this is parallel, this will be done later.
229 HeapRegionRemSet* hrrs = rem_set();
230 if (locked) {
231 hrrs->clear_locked();
232 } else {
233 hrrs->clear();
234 }
235 _claimed = InitialClaimValue;
236 }
237 zero_marked_bytes();
239 _offsets.resize(HeapRegion::GrainWords);
240 init_top_at_mark_start();
241 if (clear_space) clear(SpaceDecorator::Mangle);
242 }
244 void HeapRegion::par_clear() {
245 assert(used() == 0, "the region should have been already cleared");
246 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
247 HeapRegionRemSet* hrrs = rem_set();
248 hrrs->clear();
249 CardTableModRefBS* ct_bs =
250 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
251 ct_bs->clear(MemRegion(bottom(), end()));
252 }
254 void HeapRegion::calc_gc_efficiency() {
255 // GC efficiency is the ratio of how much space would be
256 // reclaimed over how long we predict it would take to reclaim it.
257 G1CollectedHeap* g1h = G1CollectedHeap::heap();
258 G1CollectorPolicy* g1p = g1h->g1_policy();
260 // Retrieve a prediction of the elapsed time for this region for
261 // a mixed gc because the region will only be evacuated during a
262 // mixed gc.
263 double region_elapsed_time_ms =
264 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
265 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
266 }
268 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
269 assert(!isHumongous(), "sanity / pre-condition");
270 assert(end() == _orig_end,
271 "Should be normal before the humongous object allocation");
272 assert(top() == bottom(), "should be empty");
273 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
275 _humongous_type = StartsHumongous;
276 _humongous_start_region = this;
278 set_end(new_end);
279 _offsets.set_for_starts_humongous(new_top);
280 }
282 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
283 assert(!isHumongous(), "sanity / pre-condition");
284 assert(end() == _orig_end,
285 "Should be normal before the humongous object allocation");
286 assert(top() == bottom(), "should be empty");
287 assert(first_hr->startsHumongous(), "pre-condition");
289 _humongous_type = ContinuesHumongous;
290 _humongous_start_region = first_hr;
291 }
293 void HeapRegion::set_notHumongous() {
294 assert(isHumongous(), "pre-condition");
296 if (startsHumongous()) {
297 assert(top() <= end(), "pre-condition");
298 set_end(_orig_end);
299 if (top() > end()) {
300 // at least one "continues humongous" region after it
301 set_top(end());
302 }
303 } else {
304 // continues humongous
305 assert(end() == _orig_end, "sanity");
306 }
308 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
309 _humongous_type = NotHumongous;
310 _humongous_start_region = NULL;
311 }
313 bool HeapRegion::claimHeapRegion(jint claimValue) {
314 jint current = _claimed;
315 if (current != claimValue) {
316 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
317 if (res == current) {
318 return true;
319 }
320 }
321 return false;
322 }
324 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
325 HeapWord* low = addr;
326 HeapWord* high = end();
327 while (low < high) {
328 size_t diff = pointer_delta(high, low);
329 // Must add one below to bias toward the high amount. Otherwise, if
330 // "high" were at the desired value, and "low" were one less, we
331 // would not converge on "high". This is not symmetric, because
332 // we set "high" to a block start, which might be the right one,
333 // which we don't do for "low".
334 HeapWord* middle = low + (diff+1)/2;
335 if (middle == high) return high;
336 HeapWord* mid_bs = block_start_careful(middle);
337 if (mid_bs < addr) {
338 low = middle;
339 } else {
340 high = mid_bs;
341 }
342 }
343 assert(low == high && low >= addr, "Didn't work.");
344 return low;
345 }
347 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
348 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
349 #endif // _MSC_VER
352 HeapRegion::HeapRegion(uint hrs_index,
353 G1BlockOffsetSharedArray* sharedOffsetArray,
354 MemRegion mr) :
355 G1OffsetTableContigSpace(sharedOffsetArray, mr),
356 _hrs_index(hrs_index),
357 _humongous_type(NotHumongous), _humongous_start_region(NULL),
358 _in_collection_set(false),
359 _next_in_special_set(NULL), _orig_end(NULL),
360 _claimed(InitialClaimValue), _evacuation_failed(false),
361 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
362 _young_type(NotYoung), _next_young_region(NULL),
363 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false),
364 #ifdef ASSERT
365 _containing_set(NULL),
366 #endif // ASSERT
367 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
368 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
369 _predicted_bytes_to_copy(0)
370 {
371 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
372 _orig_end = mr.end();
373 // Note that initialize() will set the start of the unmarked area of the
374 // region.
375 hr_clear(false /*par*/, false /*clear_space*/);
376 set_top(bottom());
377 record_top_and_timestamp();
379 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
380 }
382 CompactibleSpace* HeapRegion::next_compaction_space() const {
383 // We're not using an iterator given that it will wrap around when
384 // it reaches the last region and this is not what we want here.
385 G1CollectedHeap* g1h = G1CollectedHeap::heap();
386 uint index = hrs_index() + 1;
387 while (index < g1h->n_regions()) {
388 HeapRegion* hr = g1h->region_at(index);
389 if (!hr->isHumongous()) {
390 return hr;
391 }
392 index += 1;
393 }
394 return NULL;
395 }
397 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
398 bool during_conc_mark) {
399 // We always recreate the prev marking info and we'll explicitly
400 // mark all objects we find to be self-forwarded on the prev
401 // bitmap. So all objects need to be below PTAMS.
402 _prev_marked_bytes = 0;
404 if (during_initial_mark) {
405 // During initial-mark, we'll also explicitly mark all objects
406 // we find to be self-forwarded on the next bitmap. So all
407 // objects need to be below NTAMS.
408 _next_top_at_mark_start = top();
409 _next_marked_bytes = 0;
410 } else if (during_conc_mark) {
411 // During concurrent mark, all objects in the CSet (including
412 // the ones we find to be self-forwarded) are implicitly live.
413 // So all objects need to be above NTAMS.
414 _next_top_at_mark_start = bottom();
415 _next_marked_bytes = 0;
416 }
417 }
419 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
420 bool during_conc_mark,
421 size_t marked_bytes) {
422 assert(0 <= marked_bytes && marked_bytes <= used(),
423 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
424 marked_bytes, used()));
425 _prev_top_at_mark_start = top();
426 _prev_marked_bytes = marked_bytes;
427 }
429 HeapWord*
430 HeapRegion::object_iterate_mem_careful(MemRegion mr,
431 ObjectClosure* cl) {
432 G1CollectedHeap* g1h = G1CollectedHeap::heap();
433 // We used to use "block_start_careful" here. But we're actually happy
434 // to update the BOT while we do this...
435 HeapWord* cur = block_start(mr.start());
436 mr = mr.intersection(used_region());
437 if (mr.is_empty()) return NULL;
438 // Otherwise, find the obj that extends onto mr.start().
440 assert(cur <= mr.start()
441 && (oop(cur)->klass_or_null() == NULL ||
442 cur + oop(cur)->size() > mr.start()),
443 "postcondition of block_start");
444 oop obj;
445 while (cur < mr.end()) {
446 obj = oop(cur);
447 if (obj->klass_or_null() == NULL) {
448 // Ran into an unparseable point.
449 return cur;
450 } else if (!g1h->is_obj_dead(obj)) {
451 cl->do_object(obj);
452 }
453 if (cl->abort()) return cur;
454 // The check above must occur before the operation below, since an
455 // abort might invalidate the "size" operation.
456 cur += block_size(cur);
457 }
458 return NULL;
459 }
461 HeapWord*
462 HeapRegion::
463 oops_on_card_seq_iterate_careful(MemRegion mr,
464 FilterOutOfRegionClosure* cl,
465 bool filter_young,
466 jbyte* card_ptr) {
467 // Currently, we should only have to clean the card if filter_young
468 // is true and vice versa.
469 if (filter_young) {
470 assert(card_ptr != NULL, "pre-condition");
471 } else {
472 assert(card_ptr == NULL, "pre-condition");
473 }
474 G1CollectedHeap* g1h = G1CollectedHeap::heap();
476 // If we're within a stop-world GC, then we might look at a card in a
477 // GC alloc region that extends onto a GC LAB, which may not be
478 // parseable. Stop such at the "saved_mark" of the region.
479 if (g1h->is_gc_active()) {
480 mr = mr.intersection(used_region_at_save_marks());
481 } else {
482 mr = mr.intersection(used_region());
483 }
484 if (mr.is_empty()) return NULL;
485 // Otherwise, find the obj that extends onto mr.start().
487 // The intersection of the incoming mr (for the card) and the
488 // allocated part of the region is non-empty. This implies that
489 // we have actually allocated into this region. The code in
490 // G1CollectedHeap.cpp that allocates a new region sets the
491 // is_young tag on the region before allocating. Thus we
492 // safely know if this region is young.
493 if (is_young() && filter_young) {
494 return NULL;
495 }
497 assert(!is_young(), "check value of filter_young");
499 // We can only clean the card here, after we make the decision that
500 // the card is not young. And we only clean the card if we have been
501 // asked to (i.e., card_ptr != NULL).
502 if (card_ptr != NULL) {
503 *card_ptr = CardTableModRefBS::clean_card_val();
504 // We must complete this write before we do any of the reads below.
505 OrderAccess::storeload();
506 }
508 // Cache the boundaries of the memory region in some const locals
509 HeapWord* const start = mr.start();
510 HeapWord* const end = mr.end();
512 // We used to use "block_start_careful" here. But we're actually happy
513 // to update the BOT while we do this...
514 HeapWord* cur = block_start(start);
515 assert(cur <= start, "Postcondition");
517 oop obj;
519 HeapWord* next = cur;
520 while (next <= start) {
521 cur = next;
522 obj = oop(cur);
523 if (obj->klass_or_null() == NULL) {
524 // Ran into an unparseable point.
525 return cur;
526 }
527 // Otherwise...
528 next = cur + block_size(cur);
529 }
531 // If we finish the above loop...We have a parseable object that
532 // begins on or before the start of the memory region, and ends
533 // inside or spans the entire region.
535 assert(obj == oop(cur), "sanity");
536 assert(cur <= start, "Loop postcondition");
537 assert(obj->klass_or_null() != NULL, "Loop postcondition");
538 assert((cur + block_size(cur)) > start, "Loop postcondition");
540 if (!g1h->is_obj_dead(obj)) {
541 obj->oop_iterate(cl, mr);
542 }
544 while (cur < end) {
545 obj = oop(cur);
546 if (obj->klass_or_null() == NULL) {
547 // Ran into an unparseable point.
548 return cur;
549 };
551 // Otherwise:
552 next = cur + block_size(cur);
554 if (!g1h->is_obj_dead(obj)) {
555 if (next < end || !obj->is_objArray()) {
556 // This object either does not span the MemRegion
557 // boundary, or if it does it's not an array.
558 // Apply closure to whole object.
559 obj->oop_iterate(cl);
560 } else {
561 // This obj is an array that spans the boundary.
562 // Stop at the boundary.
563 obj->oop_iterate(cl, mr);
564 }
565 }
566 cur = next;
567 }
568 return NULL;
569 }
571 // Code roots support
573 void HeapRegion::add_strong_code_root(nmethod* nm) {
574 HeapRegionRemSet* hrrs = rem_set();
575 hrrs->add_strong_code_root(nm);
576 }
578 void HeapRegion::remove_strong_code_root(nmethod* nm) {
579 HeapRegionRemSet* hrrs = rem_set();
580 hrrs->remove_strong_code_root(nm);
581 }
583 void HeapRegion::migrate_strong_code_roots() {
584 assert(in_collection_set(), "only collection set regions");
585 assert(!isHumongous(),
586 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
587 HR_FORMAT_PARAMS(this)));
589 HeapRegionRemSet* hrrs = rem_set();
590 hrrs->migrate_strong_code_roots();
591 }
593 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
594 HeapRegionRemSet* hrrs = rem_set();
595 hrrs->strong_code_roots_do(blk);
596 }
598 class VerifyStrongCodeRootOopClosure: public OopClosure {
599 const HeapRegion* _hr;
600 nmethod* _nm;
601 bool _failures;
602 bool _has_oops_in_region;
604 template <class T> void do_oop_work(T* p) {
605 T heap_oop = oopDesc::load_heap_oop(p);
606 if (!oopDesc::is_null(heap_oop)) {
607 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
609 // Note: not all the oops embedded in the nmethod are in the
610 // current region. We only look at those which are.
611 if (_hr->is_in(obj)) {
612 // Object is in the region. Check that its less than top
613 if (_hr->top() <= (HeapWord*)obj) {
614 // Object is above top
615 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
616 "["PTR_FORMAT", "PTR_FORMAT") is above "
617 "top "PTR_FORMAT,
618 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
619 _failures = true;
620 return;
621 }
622 // Nmethod has at least one oop in the current region
623 _has_oops_in_region = true;
624 }
625 }
626 }
628 public:
629 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
630 _hr(hr), _failures(false), _has_oops_in_region(false) {}
632 void do_oop(narrowOop* p) { do_oop_work(p); }
633 void do_oop(oop* p) { do_oop_work(p); }
635 bool failures() { return _failures; }
636 bool has_oops_in_region() { return _has_oops_in_region; }
637 };
639 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
640 const HeapRegion* _hr;
641 bool _failures;
642 public:
643 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
644 _hr(hr), _failures(false) {}
646 void do_code_blob(CodeBlob* cb) {
647 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
648 if (nm != NULL) {
649 // Verify that the nemthod is live
650 if (!nm->is_alive()) {
651 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
652 PTR_FORMAT" in its strong code roots",
653 _hr->bottom(), _hr->end(), nm);
654 _failures = true;
655 } else {
656 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
657 nm->oops_do(&oop_cl);
658 if (!oop_cl.has_oops_in_region()) {
659 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
660 PTR_FORMAT" in its strong code roots "
661 "with no pointers into region",
662 _hr->bottom(), _hr->end(), nm);
663 _failures = true;
664 } else if (oop_cl.failures()) {
665 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
666 "failures for nmethod "PTR_FORMAT,
667 _hr->bottom(), _hr->end(), nm);
668 _failures = true;
669 }
670 }
671 }
672 }
674 bool failures() { return _failures; }
675 };
677 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
678 if (!G1VerifyHeapRegionCodeRoots) {
679 // We're not verifying code roots.
680 return;
681 }
682 if (vo == VerifyOption_G1UseMarkWord) {
683 // Marking verification during a full GC is performed after class
684 // unloading, code cache unloading, etc so the strong code roots
685 // attached to each heap region are in an inconsistent state. They won't
686 // be consistent until the strong code roots are rebuilt after the
687 // actual GC. Skip verifying the strong code roots in this particular
688 // time.
689 assert(VerifyDuringGC, "only way to get here");
690 return;
691 }
693 HeapRegionRemSet* hrrs = rem_set();
694 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
696 // if this region is empty then there should be no entries
697 // on its strong code root list
698 if (is_empty()) {
699 if (strong_code_roots_length > 0) {
700 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
701 "but has "SIZE_FORMAT" code root entries",
702 bottom(), end(), strong_code_roots_length);
703 *failures = true;
704 }
705 return;
706 }
708 if (continuesHumongous()) {
709 if (strong_code_roots_length > 0) {
710 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
711 "region but has "SIZE_FORMAT" code root entries",
712 HR_FORMAT_PARAMS(this), strong_code_roots_length);
713 *failures = true;
714 }
715 return;
716 }
718 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
719 strong_code_roots_do(&cb_cl);
721 if (cb_cl.failures()) {
722 *failures = true;
723 }
724 }
726 void HeapRegion::print() const { print_on(gclog_or_tty); }
727 void HeapRegion::print_on(outputStream* st) const {
728 if (isHumongous()) {
729 if (startsHumongous())
730 st->print(" HS");
731 else
732 st->print(" HC");
733 } else {
734 st->print(" ");
735 }
736 if (in_collection_set())
737 st->print(" CS");
738 else
739 st->print(" ");
740 if (is_young())
741 st->print(is_survivor() ? " SU" : " Y ");
742 else
743 st->print(" ");
744 if (is_empty())
745 st->print(" F");
746 else
747 st->print(" ");
748 st->print(" TS %5d", _gc_time_stamp);
749 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
750 prev_top_at_mark_start(), next_top_at_mark_start());
751 G1OffsetTableContigSpace::print_on(st);
752 }
754 class VerifyLiveClosure: public OopClosure {
755 private:
756 G1CollectedHeap* _g1h;
757 CardTableModRefBS* _bs;
758 oop _containing_obj;
759 bool _failures;
760 int _n_failures;
761 VerifyOption _vo;
762 public:
763 // _vo == UsePrevMarking -> use "prev" marking information,
764 // _vo == UseNextMarking -> use "next" marking information,
765 // _vo == UseMarkWord -> use mark word from object header.
766 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
767 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
768 _failures(false), _n_failures(0), _vo(vo)
769 {
770 BarrierSet* bs = _g1h->barrier_set();
771 if (bs->is_a(BarrierSet::CardTableModRef))
772 _bs = (CardTableModRefBS*)bs;
773 }
775 void set_containing_obj(oop obj) {
776 _containing_obj = obj;
777 }
779 bool failures() { return _failures; }
780 int n_failures() { return _n_failures; }
782 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
783 virtual void do_oop( oop* p) { do_oop_work(p); }
785 void print_object(outputStream* out, oop obj) {
786 #ifdef PRODUCT
787 Klass* k = obj->klass();
788 const char* class_name = InstanceKlass::cast(k)->external_name();
789 out->print_cr("class name %s", class_name);
790 #else // PRODUCT
791 obj->print_on(out);
792 #endif // PRODUCT
793 }
795 template <class T>
796 void do_oop_work(T* p) {
797 assert(_containing_obj != NULL, "Precondition");
798 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
799 "Precondition");
800 T heap_oop = oopDesc::load_heap_oop(p);
801 if (!oopDesc::is_null(heap_oop)) {
802 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
803 bool failed = false;
804 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
805 MutexLockerEx x(ParGCRareEvent_lock,
806 Mutex::_no_safepoint_check_flag);
808 if (!_failures) {
809 gclog_or_tty->cr();
810 gclog_or_tty->print_cr("----------");
811 }
812 if (!_g1h->is_in_closed_subset(obj)) {
813 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
814 gclog_or_tty->print_cr("Field "PTR_FORMAT
815 " of live obj "PTR_FORMAT" in region "
816 "["PTR_FORMAT", "PTR_FORMAT")",
817 p, (void*) _containing_obj,
818 from->bottom(), from->end());
819 print_object(gclog_or_tty, _containing_obj);
820 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
821 (void*) obj);
822 } else {
823 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
824 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
825 gclog_or_tty->print_cr("Field "PTR_FORMAT
826 " of live obj "PTR_FORMAT" in region "
827 "["PTR_FORMAT", "PTR_FORMAT")",
828 p, (void*) _containing_obj,
829 from->bottom(), from->end());
830 print_object(gclog_or_tty, _containing_obj);
831 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
832 "["PTR_FORMAT", "PTR_FORMAT")",
833 (void*) obj, to->bottom(), to->end());
834 print_object(gclog_or_tty, obj);
835 }
836 gclog_or_tty->print_cr("----------");
837 gclog_or_tty->flush();
838 _failures = true;
839 failed = true;
840 _n_failures++;
841 }
843 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
844 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
845 HeapRegion* to = _g1h->heap_region_containing(obj);
846 if (from != NULL && to != NULL &&
847 from != to &&
848 !to->isHumongous()) {
849 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
850 jbyte cv_field = *_bs->byte_for_const(p);
851 const jbyte dirty = CardTableModRefBS::dirty_card_val();
853 bool is_bad = !(from->is_young()
854 || to->rem_set()->contains_reference(p)
855 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
856 (_containing_obj->is_objArray() ?
857 cv_field == dirty
858 : cv_obj == dirty || cv_field == dirty));
859 if (is_bad) {
860 MutexLockerEx x(ParGCRareEvent_lock,
861 Mutex::_no_safepoint_check_flag);
863 if (!_failures) {
864 gclog_or_tty->cr();
865 gclog_or_tty->print_cr("----------");
866 }
867 gclog_or_tty->print_cr("Missing rem set entry:");
868 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
869 "of obj "PTR_FORMAT", "
870 "in region "HR_FORMAT,
871 p, (void*) _containing_obj,
872 HR_FORMAT_PARAMS(from));
873 _containing_obj->print_on(gclog_or_tty);
874 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
875 "in region "HR_FORMAT,
876 (void*) obj,
877 HR_FORMAT_PARAMS(to));
878 obj->print_on(gclog_or_tty);
879 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
880 cv_obj, cv_field);
881 gclog_or_tty->print_cr("----------");
882 gclog_or_tty->flush();
883 _failures = true;
884 if (!failed) _n_failures++;
885 }
886 }
887 }
888 }
889 }
890 };
892 // This really ought to be commoned up into OffsetTableContigSpace somehow.
893 // We would need a mechanism to make that code skip dead objects.
895 void HeapRegion::verify(VerifyOption vo,
896 bool* failures) const {
897 G1CollectedHeap* g1 = G1CollectedHeap::heap();
898 *failures = false;
899 HeapWord* p = bottom();
900 HeapWord* prev_p = NULL;
901 VerifyLiveClosure vl_cl(g1, vo);
902 bool is_humongous = isHumongous();
903 bool do_bot_verify = !is_young();
904 size_t object_num = 0;
905 while (p < top()) {
906 oop obj = oop(p);
907 size_t obj_size = block_size(p);
908 object_num += 1;
910 if (is_humongous != g1->isHumongous(obj_size) &&
911 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
912 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
913 SIZE_FORMAT" words) in a %shumongous region",
914 p, g1->isHumongous(obj_size) ? "" : "non-",
915 obj_size, is_humongous ? "" : "non-");
916 *failures = true;
917 return;
918 }
920 // If it returns false, verify_for_object() will output the
921 // appropriate messasge.
922 if (do_bot_verify &&
923 !g1->is_obj_dead(obj, this) &&
924 !_offsets.verify_for_object(p, obj_size)) {
925 *failures = true;
926 return;
927 }
929 if (!g1->is_obj_dead_cond(obj, this, vo)) {
930 if (obj->is_oop()) {
931 Klass* klass = obj->klass();
932 bool is_metaspace_object = Metaspace::contains(klass) ||
933 (vo == VerifyOption_G1UsePrevMarking &&
934 ClassLoaderDataGraph::unload_list_contains(klass));
935 if (!is_metaspace_object) {
936 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
937 "not metadata", klass, (void *)obj);
938 *failures = true;
939 return;
940 } else if (!klass->is_klass()) {
941 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
942 "not a klass", klass, (void *)obj);
943 *failures = true;
944 return;
945 } else {
946 vl_cl.set_containing_obj(obj);
947 obj->oop_iterate_no_header(&vl_cl);
948 if (vl_cl.failures()) {
949 *failures = true;
950 }
951 if (G1MaxVerifyFailures >= 0 &&
952 vl_cl.n_failures() >= G1MaxVerifyFailures) {
953 return;
954 }
955 }
956 } else {
957 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
958 *failures = true;
959 return;
960 }
961 }
962 prev_p = p;
963 p += obj_size;
964 }
966 if (p != top()) {
967 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
968 "does not match top "PTR_FORMAT, p, top());
969 *failures = true;
970 return;
971 }
973 HeapWord* the_end = end();
974 assert(p == top(), "it should still hold");
975 // Do some extra BOT consistency checking for addresses in the
976 // range [top, end). BOT look-ups in this range should yield
977 // top. No point in doing that if top == end (there's nothing there).
978 if (p < the_end) {
979 // Look up top
980 HeapWord* addr_1 = p;
981 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
982 if (b_start_1 != p) {
983 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
984 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
985 addr_1, b_start_1, p);
986 *failures = true;
987 return;
988 }
990 // Look up top + 1
991 HeapWord* addr_2 = p + 1;
992 if (addr_2 < the_end) {
993 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
994 if (b_start_2 != p) {
995 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
996 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
997 addr_2, b_start_2, p);
998 *failures = true;
999 return;
1000 }
1001 }
1003 // Look up an address between top and end
1004 size_t diff = pointer_delta(the_end, p) / 2;
1005 HeapWord* addr_3 = p + diff;
1006 if (addr_3 < the_end) {
1007 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1008 if (b_start_3 != p) {
1009 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1010 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1011 addr_3, b_start_3, p);
1012 *failures = true;
1013 return;
1014 }
1015 }
1017 // Loook up end - 1
1018 HeapWord* addr_4 = the_end - 1;
1019 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1020 if (b_start_4 != p) {
1021 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1022 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1023 addr_4, b_start_4, p);
1024 *failures = true;
1025 return;
1026 }
1027 }
1029 if (is_humongous && object_num > 1) {
1030 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1031 "but has "SIZE_FORMAT", objects",
1032 bottom(), end(), object_num);
1033 *failures = true;
1034 return;
1035 }
1037 verify_strong_code_roots(vo, failures);
1038 }
1040 void HeapRegion::verify() const {
1041 bool dummy = false;
1042 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1043 }
1045 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1046 // away eventually.
1048 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1049 set_top(bottom());
1050 set_saved_mark_word(bottom());
1051 CompactibleSpace::clear(mangle_space);
1052 _offsets.zero_bottom_entry();
1053 _offsets.initialize_threshold();
1054 }
1056 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1057 Space::set_bottom(new_bottom);
1058 _offsets.set_bottom(new_bottom);
1059 }
1061 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1062 Space::set_end(new_end);
1063 _offsets.resize(new_end - bottom());
1064 }
1066 void G1OffsetTableContigSpace::print() const {
1067 print_short();
1068 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1069 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1070 bottom(), top(), _offsets.threshold(), end());
1071 }
1073 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1074 return _offsets.initialize_threshold();
1075 }
1077 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1078 HeapWord* end) {
1079 _offsets.alloc_block(start, end);
1080 return _offsets.threshold();
1081 }
1083 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1084 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1085 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1086 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1087 return top();
1088 else
1089 return Space::saved_mark_word();
1090 }
1092 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1093 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1094 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1096 if (_gc_time_stamp < curr_gc_time_stamp) {
1097 // The order of these is important, as another thread might be
1098 // about to start scanning this region. If it does so after
1099 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1100 // will be false, and it will pick up top() as the high water mark
1101 // of region. If it does so after _gc_time_stamp = ..., then it
1102 // will pick up the right saved_mark_word() as the high water mark
1103 // of the region. Either way, the behaviour will be correct.
1104 Space::set_saved_mark_word(top());
1105 OrderAccess::storestore();
1106 _gc_time_stamp = curr_gc_time_stamp;
1107 // No need to do another barrier to flush the writes above. If
1108 // this is called in parallel with other threads trying to
1109 // allocate into the region, the caller should call this while
1110 // holding a lock and when the lock is released the writes will be
1111 // flushed.
1112 }
1113 }
1115 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1116 object_iterate(blk);
1117 }
1119 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1120 HeapWord* p = bottom();
1121 while (p < top()) {
1122 if (block_is_obj(p)) {
1123 blk->do_object(oop(p));
1124 }
1125 p += block_size(p);
1126 }
1127 }
1129 #define block_is_always_obj(q) true
1130 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1131 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1132 }
1133 #undef block_is_always_obj
1135 G1OffsetTableContigSpace::
1136 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1137 MemRegion mr) :
1138 _offsets(sharedOffsetArray, mr),
1139 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1140 _gc_time_stamp(0)
1141 {
1142 _offsets.set_space(this);
1143 // false ==> we'll do the clearing if there's clearing to be done.
1144 CompactibleSpace::initialize(mr, false, SpaceDecorator::Mangle);
1145 _top = bottom();
1146 _offsets.zero_bottom_entry();
1147 _offsets.initialize_threshold();
1148 }