Thu, 11 Dec 2008 12:05:08 -0800
6578152: fill_region_with_object has usability and safety issues
Reviewed-by: apetrusenko, ysr
1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_generation.cpp.incl"
28 Generation::Generation(ReservedSpace rs, size_t initial_size, int level) :
29 _level(level),
30 _ref_processor(NULL) {
31 if (!_virtual_space.initialize(rs, initial_size)) {
32 vm_exit_during_initialization("Could not reserve enough space for "
33 "object heap");
34 }
35 // Mangle all of the the initial generation.
36 if (ZapUnusedHeapArea) {
37 MemRegion mangle_region((HeapWord*)_virtual_space.low(),
38 (HeapWord*)_virtual_space.high());
39 SpaceMangler::mangle_region(mangle_region);
40 }
41 _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),
42 (HeapWord*)_virtual_space.high_boundary());
43 }
45 GenerationSpec* Generation::spec() {
46 GenCollectedHeap* gch = GenCollectedHeap::heap();
47 assert(0 <= level() && level() < gch->_n_gens, "Bad gen level");
48 return gch->_gen_specs[level()];
49 }
51 size_t Generation::max_capacity() const {
52 return reserved().byte_size();
53 }
55 void Generation::print_heap_change(size_t prev_used) const {
56 if (PrintGCDetails && Verbose) {
57 gclog_or_tty->print(" " SIZE_FORMAT
58 "->" SIZE_FORMAT
59 "(" SIZE_FORMAT ")",
60 prev_used, used(), capacity());
61 } else {
62 gclog_or_tty->print(" " SIZE_FORMAT "K"
63 "->" SIZE_FORMAT "K"
64 "(" SIZE_FORMAT "K)",
65 prev_used / K, used() / K, capacity() / K);
66 }
67 }
69 // By default we get a single threaded default reference processor;
70 // generations needing multi-threaded refs discovery override this method.
71 void Generation::ref_processor_init() {
72 assert(_ref_processor == NULL, "a reference processor already exists");
73 assert(!_reserved.is_empty(), "empty generation?");
74 _ref_processor =
75 new ReferenceProcessor(_reserved, // span
76 refs_discovery_is_atomic(), // atomic_discovery
77 refs_discovery_is_mt()); // mt_discovery
78 if (_ref_processor == NULL) {
79 vm_exit_during_initialization("Could not allocate ReferenceProcessor object");
80 }
81 }
83 void Generation::print() const { print_on(tty); }
85 void Generation::print_on(outputStream* st) const {
86 st->print(" %-20s", name());
87 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
88 capacity()/K, used()/K);
89 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
90 _virtual_space.low_boundary(),
91 _virtual_space.high(),
92 _virtual_space.high_boundary());
93 }
95 void Generation::print_summary_info() { print_summary_info_on(tty); }
97 void Generation::print_summary_info_on(outputStream* st) {
98 StatRecord* sr = stat_record();
99 double time = sr->accumulated_time.seconds();
100 st->print_cr("[Accumulated GC generation %d time %3.7f secs, "
101 "%d GC's, avg GC time %3.7f]",
102 level(), time, sr->invocations,
103 sr->invocations > 0 ? time / sr->invocations : 0.0);
104 }
106 // Utility iterator classes
108 class GenerationIsInReservedClosure : public SpaceClosure {
109 public:
110 const void* _p;
111 Space* sp;
112 virtual void do_space(Space* s) {
113 if (sp == NULL) {
114 if (s->is_in_reserved(_p)) sp = s;
115 }
116 }
117 GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {}
118 };
120 class GenerationIsInClosure : public SpaceClosure {
121 public:
122 const void* _p;
123 Space* sp;
124 virtual void do_space(Space* s) {
125 if (sp == NULL) {
126 if (s->is_in(_p)) sp = s;
127 }
128 }
129 GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {}
130 };
132 bool Generation::is_in(const void* p) const {
133 GenerationIsInClosure blk(p);
134 ((Generation*)this)->space_iterate(&blk);
135 return blk.sp != NULL;
136 }
138 DefNewGeneration* Generation::as_DefNewGeneration() {
139 assert((kind() == Generation::DefNew) ||
140 (kind() == Generation::ParNew) ||
141 (kind() == Generation::ASParNew),
142 "Wrong youngest generation type");
143 return (DefNewGeneration*) this;
144 }
146 Generation* Generation::next_gen() const {
147 GenCollectedHeap* gch = GenCollectedHeap::heap();
148 int next = level() + 1;
149 if (next < gch->_n_gens) {
150 return gch->_gens[next];
151 } else {
152 return NULL;
153 }
154 }
156 size_t Generation::max_contiguous_available() const {
157 // The largest number of contiguous free words in this or any higher generation.
158 size_t max = 0;
159 for (const Generation* gen = this; gen != NULL; gen = gen->next_gen()) {
160 size_t avail = gen->contiguous_available();
161 if (avail > max) {
162 max = avail;
163 }
164 }
165 return max;
166 }
168 bool Generation::promotion_attempt_is_safe(size_t promotion_in_bytes,
169 bool not_used) const {
170 if (PrintGC && Verbose) {
171 gclog_or_tty->print_cr("Generation::promotion_attempt_is_safe"
172 " contiguous_available: " SIZE_FORMAT
173 " promotion_in_bytes: " SIZE_FORMAT,
174 max_contiguous_available(), promotion_in_bytes);
175 }
176 return max_contiguous_available() >= promotion_in_bytes;
177 }
179 // Ignores "ref" and calls allocate().
180 oop Generation::promote(oop obj, size_t obj_size) {
181 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
183 #ifndef PRODUCT
184 if (Universe::heap()->promotion_should_fail()) {
185 return NULL;
186 }
187 #endif // #ifndef PRODUCT
189 HeapWord* result = allocate(obj_size, false);
190 if (result != NULL) {
191 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
192 return oop(result);
193 } else {
194 GenCollectedHeap* gch = GenCollectedHeap::heap();
195 return gch->handle_failed_promotion(this, obj, obj_size);
196 }
197 }
199 oop Generation::par_promote(int thread_num,
200 oop obj, markOop m, size_t word_sz) {
201 // Could do a bad general impl here that gets a lock. But no.
202 ShouldNotCallThis();
203 return NULL;
204 }
206 void Generation::par_promote_alloc_undo(int thread_num,
207 HeapWord* obj, size_t word_sz) {
208 // Could do a bad general impl here that gets a lock. But no.
209 guarantee(false, "No good general implementation.");
210 }
212 Space* Generation::space_containing(const void* p) const {
213 GenerationIsInReservedClosure blk(p);
214 // Cast away const
215 ((Generation*)this)->space_iterate(&blk);
216 return blk.sp;
217 }
219 // Some of these are mediocre general implementations. Should be
220 // overridden to get better performance.
222 class GenerationBlockStartClosure : public SpaceClosure {
223 public:
224 const void* _p;
225 HeapWord* _start;
226 virtual void do_space(Space* s) {
227 if (_start == NULL && s->is_in_reserved(_p)) {
228 _start = s->block_start(_p);
229 }
230 }
231 GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; }
232 };
234 HeapWord* Generation::block_start(const void* p) const {
235 GenerationBlockStartClosure blk(p);
236 // Cast away const
237 ((Generation*)this)->space_iterate(&blk);
238 return blk._start;
239 }
241 class GenerationBlockSizeClosure : public SpaceClosure {
242 public:
243 const HeapWord* _p;
244 size_t size;
245 virtual void do_space(Space* s) {
246 if (size == 0 && s->is_in_reserved(_p)) {
247 size = s->block_size(_p);
248 }
249 }
250 GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; }
251 };
253 size_t Generation::block_size(const HeapWord* p) const {
254 GenerationBlockSizeClosure blk(p);
255 // Cast away const
256 ((Generation*)this)->space_iterate(&blk);
257 assert(blk.size > 0, "seems reasonable");
258 return blk.size;
259 }
261 class GenerationBlockIsObjClosure : public SpaceClosure {
262 public:
263 const HeapWord* _p;
264 bool is_obj;
265 virtual void do_space(Space* s) {
266 if (!is_obj && s->is_in_reserved(_p)) {
267 is_obj |= s->block_is_obj(_p);
268 }
269 }
270 GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; }
271 };
273 bool Generation::block_is_obj(const HeapWord* p) const {
274 GenerationBlockIsObjClosure blk(p);
275 // Cast away const
276 ((Generation*)this)->space_iterate(&blk);
277 return blk.is_obj;
278 }
280 class GenerationOopIterateClosure : public SpaceClosure {
281 public:
282 OopClosure* cl;
283 MemRegion mr;
284 virtual void do_space(Space* s) {
285 s->oop_iterate(mr, cl);
286 }
287 GenerationOopIterateClosure(OopClosure* _cl, MemRegion _mr) :
288 cl(_cl), mr(_mr) {}
289 };
291 void Generation::oop_iterate(OopClosure* cl) {
292 GenerationOopIterateClosure blk(cl, _reserved);
293 space_iterate(&blk);
294 }
296 void Generation::oop_iterate(MemRegion mr, OopClosure* cl) {
297 GenerationOopIterateClosure blk(cl, mr);
298 space_iterate(&blk);
299 }
301 void Generation::younger_refs_in_space_iterate(Space* sp,
302 OopsInGenClosure* cl) {
303 GenRemSet* rs = SharedHeap::heap()->rem_set();
304 rs->younger_refs_in_space_iterate(sp, cl);
305 }
307 class GenerationObjIterateClosure : public SpaceClosure {
308 private:
309 ObjectClosure* _cl;
310 public:
311 virtual void do_space(Space* s) {
312 s->object_iterate(_cl);
313 }
314 GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
315 };
317 void Generation::object_iterate(ObjectClosure* cl) {
318 GenerationObjIterateClosure blk(cl);
319 space_iterate(&blk);
320 }
322 void Generation::prepare_for_compaction(CompactPoint* cp) {
323 // Generic implementation, can be specialized
324 CompactibleSpace* space = first_compaction_space();
325 while (space != NULL) {
326 space->prepare_for_compaction(cp);
327 space = space->next_compaction_space();
328 }
329 }
331 class AdjustPointersClosure: public SpaceClosure {
332 public:
333 void do_space(Space* sp) {
334 sp->adjust_pointers();
335 }
336 };
338 void Generation::adjust_pointers() {
339 // Note that this is done over all spaces, not just the compactible
340 // ones.
341 AdjustPointersClosure blk;
342 space_iterate(&blk, true);
343 }
345 void Generation::compact() {
346 CompactibleSpace* sp = first_compaction_space();
347 while (sp != NULL) {
348 sp->compact();
349 sp = sp->next_compaction_space();
350 }
351 }
353 CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size,
354 int level,
355 GenRemSet* remset) :
356 Generation(rs, initial_byte_size, level), _rs(remset)
357 {
358 HeapWord* start = (HeapWord*)rs.base();
359 size_t reserved_byte_size = rs.size();
360 assert((uintptr_t(start) & 3) == 0, "bad alignment");
361 assert((reserved_byte_size & 3) == 0, "bad alignment");
362 MemRegion reserved_mr(start, heap_word_size(reserved_byte_size));
363 _bts = new BlockOffsetSharedArray(reserved_mr,
364 heap_word_size(initial_byte_size));
365 MemRegion committed_mr(start, heap_word_size(initial_byte_size));
366 _rs->resize_covered_region(committed_mr);
367 if (_bts == NULL)
368 vm_exit_during_initialization("Could not allocate a BlockOffsetArray");
370 // Verify that the start and end of this generation is the start of a card.
371 // If this wasn't true, a single card could span more than on generation,
372 // which would cause problems when we commit/uncommit memory, and when we
373 // clear and dirty cards.
374 guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned");
375 if (reserved_mr.end() != Universe::heap()->reserved_region().end()) {
376 // Don't check at the very end of the heap as we'll assert that we're probing off
377 // the end if we try.
378 guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned");
379 }
380 }
382 bool CardGeneration::expand(size_t bytes, size_t expand_bytes) {
383 assert_locked_or_safepoint(Heap_lock);
384 if (bytes == 0) {
385 return true; // That's what grow_by(0) would return
386 }
387 size_t aligned_bytes = ReservedSpace::page_align_size_up(bytes);
388 if (aligned_bytes == 0){
389 // The alignment caused the number of bytes to wrap. An expand_by(0) will
390 // return true with the implication that an expansion was done when it
391 // was not. A call to expand implies a best effort to expand by "bytes"
392 // but not a guarantee. Align down to give a best effort. This is likely
393 // the most that the generation can expand since it has some capacity to
394 // start with.
395 aligned_bytes = ReservedSpace::page_align_size_down(bytes);
396 }
397 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
398 bool success = false;
399 if (aligned_expand_bytes > aligned_bytes) {
400 success = grow_by(aligned_expand_bytes);
401 }
402 if (!success) {
403 success = grow_by(aligned_bytes);
404 }
405 if (!success) {
406 success = grow_to_reserved();
407 }
408 if (PrintGC && Verbose) {
409 if (success && GC_locker::is_active()) {
410 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");
411 }
412 }
414 return success;
415 }
418 // No young generation references, clear this generation's cards.
419 void CardGeneration::clear_remembered_set() {
420 _rs->clear(reserved());
421 }
424 // Objects in this generation may have moved, invalidate this
425 // generation's cards.
426 void CardGeneration::invalidate_remembered_set() {
427 _rs->invalidate(used_region());
428 }
431 // Currently nothing to do.
432 void CardGeneration::prepare_for_verify() {}
435 void OneContigSpaceCardGeneration::collect(bool full,
436 bool clear_all_soft_refs,
437 size_t size,
438 bool is_tlab) {
439 SpecializationStats::clear();
440 // Temporarily expand the span of our ref processor, so
441 // refs discovery is over the entire heap, not just this generation
442 ReferenceProcessorSpanMutator
443 x(ref_processor(), GenCollectedHeap::heap()->reserved_region());
444 GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs);
445 SpecializationStats::print();
446 }
448 HeapWord*
449 OneContigSpaceCardGeneration::expand_and_allocate(size_t word_size,
450 bool is_tlab,
451 bool parallel) {
452 assert(!is_tlab, "OneContigSpaceCardGeneration does not support TLAB allocation");
453 if (parallel) {
454 MutexLocker x(ParGCRareEvent_lock);
455 HeapWord* result = NULL;
456 size_t byte_size = word_size * HeapWordSize;
457 while (true) {
458 expand(byte_size, _min_heap_delta_bytes);
459 if (GCExpandToAllocateDelayMillis > 0) {
460 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false);
461 }
462 result = _the_space->par_allocate(word_size);
463 if ( result != NULL) {
464 return result;
465 } else {
466 // If there's not enough expansion space available, give up.
467 if (_virtual_space.uncommitted_size() < byte_size) {
468 return NULL;
469 }
470 // else try again
471 }
472 }
473 } else {
474 expand(word_size*HeapWordSize, _min_heap_delta_bytes);
475 return _the_space->allocate(word_size);
476 }
477 }
479 bool OneContigSpaceCardGeneration::expand(size_t bytes, size_t expand_bytes) {
480 GCMutexLocker x(ExpandHeap_lock);
481 return CardGeneration::expand(bytes, expand_bytes);
482 }
485 void OneContigSpaceCardGeneration::shrink(size_t bytes) {
486 assert_locked_or_safepoint(ExpandHeap_lock);
487 size_t size = ReservedSpace::page_align_size_down(bytes);
488 if (size > 0) {
489 shrink_by(size);
490 }
491 }
494 size_t OneContigSpaceCardGeneration::capacity() const {
495 return _the_space->capacity();
496 }
499 size_t OneContigSpaceCardGeneration::used() const {
500 return _the_space->used();
501 }
504 size_t OneContigSpaceCardGeneration::free() const {
505 return _the_space->free();
506 }
508 MemRegion OneContigSpaceCardGeneration::used_region() const {
509 return the_space()->used_region();
510 }
512 size_t OneContigSpaceCardGeneration::unsafe_max_alloc_nogc() const {
513 return _the_space->free();
514 }
516 size_t OneContigSpaceCardGeneration::contiguous_available() const {
517 return _the_space->free() + _virtual_space.uncommitted_size();
518 }
520 bool OneContigSpaceCardGeneration::grow_by(size_t bytes) {
521 assert_locked_or_safepoint(ExpandHeap_lock);
522 bool result = _virtual_space.expand_by(bytes);
523 if (result) {
524 size_t new_word_size =
525 heap_word_size(_virtual_space.committed_size());
526 MemRegion mr(_the_space->bottom(), new_word_size);
527 // Expand card table
528 Universe::heap()->barrier_set()->resize_covered_region(mr);
529 // Expand shared block offset array
530 _bts->resize(new_word_size);
532 // Fix for bug #4668531
533 if (ZapUnusedHeapArea) {
534 MemRegion mangle_region(_the_space->end(),
535 (HeapWord*)_virtual_space.high());
536 SpaceMangler::mangle_region(mangle_region);
537 }
539 // Expand space -- also expands space's BOT
540 // (which uses (part of) shared array above)
541 _the_space->set_end((HeapWord*)_virtual_space.high());
543 // update the space and generation capacity counters
544 update_counters();
546 if (Verbose && PrintGC) {
547 size_t new_mem_size = _virtual_space.committed_size();
548 size_t old_mem_size = new_mem_size - bytes;
549 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by "
550 SIZE_FORMAT "K to " SIZE_FORMAT "K",
551 name(), old_mem_size/K, bytes/K, new_mem_size/K);
552 }
553 }
554 return result;
555 }
558 bool OneContigSpaceCardGeneration::grow_to_reserved() {
559 assert_locked_or_safepoint(ExpandHeap_lock);
560 bool success = true;
561 const size_t remaining_bytes = _virtual_space.uncommitted_size();
562 if (remaining_bytes > 0) {
563 success = grow_by(remaining_bytes);
564 DEBUG_ONLY(if (!success) warning("grow to reserved failed");)
565 }
566 return success;
567 }
569 void OneContigSpaceCardGeneration::shrink_by(size_t bytes) {
570 assert_locked_or_safepoint(ExpandHeap_lock);
571 // Shrink committed space
572 _virtual_space.shrink_by(bytes);
573 // Shrink space; this also shrinks the space's BOT
574 _the_space->set_end((HeapWord*) _virtual_space.high());
575 size_t new_word_size = heap_word_size(_the_space->capacity());
576 // Shrink the shared block offset array
577 _bts->resize(new_word_size);
578 MemRegion mr(_the_space->bottom(), new_word_size);
579 // Shrink the card table
580 Universe::heap()->barrier_set()->resize_covered_region(mr);
582 if (Verbose && PrintGC) {
583 size_t new_mem_size = _virtual_space.committed_size();
584 size_t old_mem_size = new_mem_size + bytes;
585 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
586 name(), old_mem_size/K, new_mem_size/K);
587 }
588 }
590 // Currently nothing to do.
591 void OneContigSpaceCardGeneration::prepare_for_verify() {}
594 void OneContigSpaceCardGeneration::object_iterate(ObjectClosure* blk) {
595 _the_space->object_iterate(blk);
596 }
598 void OneContigSpaceCardGeneration::space_iterate(SpaceClosure* blk,
599 bool usedOnly) {
600 blk->do_space(_the_space);
601 }
603 void OneContigSpaceCardGeneration::object_iterate_since_last_GC(ObjectClosure* blk) {
604 // Deal with delayed initialization of _the_space,
605 // and lack of initialization of _last_gc.
606 if (_last_gc.space() == NULL) {
607 assert(the_space() != NULL, "shouldn't be NULL");
608 _last_gc = the_space()->bottom_mark();
609 }
610 the_space()->object_iterate_from(_last_gc, blk);
611 }
613 void OneContigSpaceCardGeneration::younger_refs_iterate(OopsInGenClosure* blk) {
614 blk->set_generation(this);
615 younger_refs_in_space_iterate(_the_space, blk);
616 blk->reset_generation();
617 }
619 void OneContigSpaceCardGeneration::save_marks() {
620 _the_space->set_saved_mark();
621 }
624 void OneContigSpaceCardGeneration::reset_saved_marks() {
625 _the_space->reset_saved_mark();
626 }
629 bool OneContigSpaceCardGeneration::no_allocs_since_save_marks() {
630 return _the_space->saved_mark_at_top();
631 }
633 #define OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
634 \
635 void OneContigSpaceCardGeneration:: \
636 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
637 blk->set_generation(this); \
638 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \
639 blk->reset_generation(); \
640 save_marks(); \
641 }
643 ALL_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN)
645 #undef OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN
648 void OneContigSpaceCardGeneration::gc_epilogue(bool full) {
649 _last_gc = WaterMark(the_space(), the_space()->top());
651 // update the generation and space performance counters
652 update_counters();
653 if (ZapUnusedHeapArea) {
654 the_space()->check_mangled_unused_area_complete();
655 }
656 }
658 void OneContigSpaceCardGeneration::record_spaces_top() {
659 assert(ZapUnusedHeapArea, "Not mangling unused space");
660 the_space()->set_top_for_allocations();
661 }
663 void OneContigSpaceCardGeneration::verify(bool allow_dirty) {
664 the_space()->verify(allow_dirty);
665 }
667 void OneContigSpaceCardGeneration::print_on(outputStream* st) const {
668 Generation::print_on(st);
669 st->print(" the");
670 the_space()->print_on(st);
671 }