1 /*
2 * Copyright (c) 2005, 2025, 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.
18 *
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
21 * questions.
22 *
23 */
24
25 #include "classfile/classLoaderDataGraph.hpp"
26 #include "classfile/javaClasses.inline.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/nmethod.hpp"
32 #include "compiler/oopMap.hpp"
33 #include "gc/parallel/objectStartArray.inline.hpp"
34 #include "gc/parallel/parallelArguments.hpp"
35 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
36 #include "gc/parallel/parMarkBitMap.inline.hpp"
37 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
38 #include "gc/parallel/psCompactionManager.inline.hpp"
39 #include "gc/parallel/psOldGen.hpp"
40 #include "gc/parallel/psParallelCompact.inline.hpp"
41 #include "gc/parallel/psPromotionManager.inline.hpp"
42 #include "gc/parallel/psRootType.hpp"
43 #include "gc/parallel/psScavenge.hpp"
44 #include "gc/parallel/psStringDedup.hpp"
45 #include "gc/parallel/psYoungGen.hpp"
46 #include "gc/shared/classUnloadingContext.hpp"
47 #include "gc/shared/fullGCForwarding.inline.hpp"
48 #include "gc/shared/gcCause.hpp"
49 #include "gc/shared/gcHeapSummary.hpp"
50 #include "gc/shared/gcId.hpp"
51 #include "gc/shared/gcLocker.hpp"
52 #include "gc/shared/gcTimer.hpp"
53 #include "gc/shared/gcTrace.hpp"
54 #include "gc/shared/gcTraceTime.inline.hpp"
55 #include "gc/shared/gcVMOperations.hpp"
56 #include "gc/shared/isGCActiveMark.hpp"
57 #include "gc/shared/oopStorage.inline.hpp"
58 #include "gc/shared/oopStorageSet.inline.hpp"
59 #include "gc/shared/oopStorageSetParState.inline.hpp"
60 #include "gc/shared/preservedMarks.inline.hpp"
61 #include "gc/shared/referencePolicy.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
64 #include "gc/shared/spaceDecorator.hpp"
65 #include "gc/shared/taskTerminator.hpp"
66 #include "gc/shared/weakProcessor.inline.hpp"
67 #include "gc/shared/workerPolicy.hpp"
68 #include "gc/shared/workerThread.hpp"
69 #include "gc/shared/workerUtils.hpp"
70 #include "logging/log.hpp"
71 #include "memory/iterator.inline.hpp"
72 #include "memory/memoryReserver.hpp"
73 #include "memory/metaspaceUtils.hpp"
74 #include "memory/resourceArea.hpp"
75 #include "memory/universe.hpp"
76 #include "nmt/memTracker.hpp"
77 #include "oops/access.inline.hpp"
78 #include "oops/instanceClassLoaderKlass.inline.hpp"
79 #include "oops/instanceKlass.inline.hpp"
80 #include "oops/instanceMirrorKlass.inline.hpp"
81 #include "oops/methodData.hpp"
82 #include "oops/objArrayKlass.inline.hpp"
83 #include "oops/oop.inline.hpp"
84 #include "runtime/atomicAccess.hpp"
85 #include "runtime/handles.inline.hpp"
86 #include "runtime/java.hpp"
87 #include "runtime/safepoint.hpp"
88 #include "runtime/threads.hpp"
89 #include "runtime/vmThread.hpp"
90 #include "services/memoryService.hpp"
91 #include "utilities/align.hpp"
92 #include "utilities/debug.hpp"
93 #include "utilities/events.hpp"
94 #include "utilities/formatBuffer.hpp"
95 #include "utilities/macros.hpp"
96 #include "utilities/stack.inline.hpp"
97 #if INCLUDE_JVMCI
98 #include "jvmci/jvmci.hpp"
99 #endif
100
101 #include <math.h>
102
103 // All sizes are in HeapWords.
104 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
105 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
106 static_assert(ParallelCompactData::RegionSize >= BitsPerWord, "region-start bit word-aligned");
107 const size_t ParallelCompactData::RegionSizeBytes =
108 RegionSize << LogHeapWordSize;
109 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
110 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
111 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
112
113 const ParallelCompactData::RegionData::region_sz_t
114 ParallelCompactData::RegionData::dc_shift = 27;
115
116 const ParallelCompactData::RegionData::region_sz_t
117 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
118
119 const ParallelCompactData::RegionData::region_sz_t
120 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
121
122 const ParallelCompactData::RegionData::region_sz_t
123 ParallelCompactData::RegionData::los_mask = ~dc_mask;
124
125 const ParallelCompactData::RegionData::region_sz_t
126 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
127
128 const ParallelCompactData::RegionData::region_sz_t
129 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
130
131 bool ParallelCompactData::RegionData::is_clear() {
132 return (_destination == nullptr) &&
133 (_source_region == 0) &&
134 (_partial_obj_addr == nullptr) &&
135 (_partial_obj_size == 0) &&
136 (_dc_and_los == 0) &&
137 (_shadow_state == 0);
138 }
139
140 #ifdef ASSERT
141 void ParallelCompactData::RegionData::verify_clear() {
142 assert(_destination == nullptr, "inv");
143 assert(_source_region == 0, "inv");
144 assert(_partial_obj_addr == nullptr, "inv");
145 assert(_partial_obj_size == 0, "inv");
146 assert(_dc_and_los == 0, "inv");
147 assert(_shadow_state == 0, "inv");
148 }
149 #endif
150
151 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
152
153 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
154 ReferenceProcessor* PSParallelCompact::_ref_processor = nullptr;
155
156 void SplitInfo::record(size_t split_region_idx, HeapWord* split_point, size_t preceding_live_words) {
157 assert(split_region_idx != 0, "precondition");
158
159 // Obj denoted by split_point will be deferred to the next space.
160 assert(split_point != nullptr, "precondition");
161
162 const ParallelCompactData& sd = PSParallelCompact::summary_data();
163
164 PSParallelCompact::RegionData* split_region_ptr = sd.region(split_region_idx);
165 assert(preceding_live_words < split_region_ptr->data_size(), "inv");
166
167 HeapWord* preceding_destination = split_region_ptr->destination();
168 assert(preceding_destination != nullptr, "inv");
169
170 // How many regions does the preceding part occupy
171 uint preceding_destination_count;
172 if (preceding_live_words == 0) {
173 preceding_destination_count = 0;
174 } else {
175 // -1 so that the ending address doesn't fall on the region-boundary
176 if (sd.region_align_down(preceding_destination) ==
177 sd.region_align_down(preceding_destination + preceding_live_words - 1)) {
178 preceding_destination_count = 1;
179 } else {
180 preceding_destination_count = 2;
181 }
182 }
183
184 _split_region_idx = split_region_idx;
185 _split_point = split_point;
186 _preceding_live_words = preceding_live_words;
187 _preceding_destination = preceding_destination;
188 _preceding_destination_count = preceding_destination_count;
189 }
190
191 void SplitInfo::clear()
192 {
193 _split_region_idx = 0;
194 _split_point = nullptr;
195 _preceding_live_words = 0;
196 _preceding_destination = nullptr;
197 _preceding_destination_count = 0;
198 assert(!is_valid(), "sanity");
199 }
200
201 #ifdef ASSERT
202 void SplitInfo::verify_clear()
203 {
204 assert(_split_region_idx == 0, "not clear");
205 assert(_split_point == nullptr, "not clear");
206 assert(_preceding_live_words == 0, "not clear");
207 assert(_preceding_destination == nullptr, "not clear");
208 assert(_preceding_destination_count == 0, "not clear");
209 }
210 #endif // #ifdef ASSERT
211
212
213 void PSParallelCompact::print_on(outputStream* st) {
214 _mark_bitmap.print_on(st);
215 }
216
217 ParallelCompactData::ParallelCompactData() :
218 _heap_start(nullptr),
219 DEBUG_ONLY(_heap_end(nullptr) COMMA)
220 _region_vspace(nullptr),
221 _reserved_byte_size(0),
222 _region_data(nullptr),
223 _region_count(0) {}
224
225 bool ParallelCompactData::initialize(MemRegion reserved_heap)
226 {
227 _heap_start = reserved_heap.start();
228 const size_t heap_size = reserved_heap.word_size();
229 DEBUG_ONLY(_heap_end = _heap_start + heap_size;)
230
231 assert(region_align_down(_heap_start) == _heap_start,
232 "region start not aligned");
233
234 return initialize_region_data(heap_size);
235 }
236
237 PSVirtualSpace*
238 ParallelCompactData::create_vspace(size_t count, size_t element_size)
239 {
240 const size_t raw_bytes = count * element_size;
241 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
242 const size_t granularity = os::vm_allocation_granularity();
243 const size_t rs_align = MAX2(page_sz, granularity);
244
245 _reserved_byte_size = align_up(raw_bytes, rs_align);
246
247 ReservedSpace rs = MemoryReserver::reserve(_reserved_byte_size,
248 rs_align,
249 page_sz,
250 mtGC);
251
252 if (!rs.is_reserved()) {
253 // Failed to reserve memory.
254 return nullptr;
255 }
256
257 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, rs.base(),
258 rs.size(), page_sz);
259
260 MemTracker::record_virtual_memory_tag(rs, mtGC);
261
262 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
263
264 if (!vspace->expand_by(_reserved_byte_size)) {
265 // Failed to commit memory.
266
267 delete vspace;
268
269 // Release memory reserved in the space.
270 MemoryReserver::release(rs);
271
272 return nullptr;
273 }
274
275 return vspace;
276 }
277
278 bool ParallelCompactData::initialize_region_data(size_t heap_size)
279 {
280 assert(is_aligned(heap_size, RegionSize), "precondition");
281
282 const size_t count = heap_size >> Log2RegionSize;
283 _region_vspace = create_vspace(count, sizeof(RegionData));
284 if (_region_vspace != nullptr) {
285 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
286 _region_count = count;
287 return true;
288 }
289 return false;
290 }
291
292 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
293 assert(beg_region <= _region_count, "beg_region out of range");
294 assert(end_region <= _region_count, "end_region out of range");
295
296 const size_t region_cnt = end_region - beg_region;
297 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
298 }
299
300 // The total live words on src_region would overflow the target space, so find
301 // the overflowing object and record the split point. The invariant is that an
302 // obj should not cross space boundary.
303 HeapWord* ParallelCompactData::summarize_split_space(size_t src_region,
304 SplitInfo& split_info,
305 HeapWord* const destination,
306 HeapWord* const target_end,
307 HeapWord** target_next) {
308 assert(destination <= target_end, "sanity");
309 assert(destination + _region_data[src_region].data_size() > target_end,
310 "region should not fit into target space");
311 assert(is_region_aligned(target_end), "sanity");
312
313 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
314
315 if (destination + partial_obj_size > target_end) {
316 assert(partial_obj_size > 0, "inv");
317 // The overflowing obj is from a previous region.
318 //
319 // source-regions:
320 //
321 // ***************
322 // | A|AA |
323 // ***************
324 // ^
325 // | split-point
326 //
327 // dest-region:
328 //
329 // ********
330 // |~~~~A |
331 // ********
332 // ^^
333 // || target-space-end
334 // |
335 // | destination
336 //
337 // AAA would overflow target-space.
338 //
339 HeapWord* overflowing_obj = _region_data[src_region].partial_obj_addr();
340 size_t split_region = addr_to_region_idx(overflowing_obj);
341
342 // The number of live words before the overflowing object on this split region
343 size_t preceding_live_words;
344 if (is_region_aligned(overflowing_obj)) {
345 preceding_live_words = 0;
346 } else {
347 // Words accounted by the overflowing object on the split region
348 size_t overflowing_size = pointer_delta(region_align_up(overflowing_obj), overflowing_obj);
349 preceding_live_words = region(split_region)->data_size() - overflowing_size;
350 }
351
352 split_info.record(split_region, overflowing_obj, preceding_live_words);
353
354 // The [overflowing_obj, src_region_start) part has been accounted for, so
355 // must move back the new_top, now that this overflowing obj is deferred.
356 HeapWord* new_top = destination - pointer_delta(region_to_addr(src_region), overflowing_obj);
357
358 // If the overflowing obj was relocated to its original destination,
359 // those destination regions would have their source_region set. Now that
360 // this overflowing obj is relocated somewhere else, reset the
361 // source_region.
362 {
363 size_t range_start = addr_to_region_idx(region_align_up(new_top));
364 size_t range_end = addr_to_region_idx(region_align_up(destination));
365 for (size_t i = range_start; i < range_end; ++i) {
366 region(i)->set_source_region(0);
367 }
368 }
369
370 // Update new top of target space
371 *target_next = new_top;
372
373 return overflowing_obj;
374 }
375
376 // Obj-iteration to locate the overflowing obj
377 HeapWord* region_start = region_to_addr(src_region);
378 HeapWord* region_end = region_start + RegionSize;
379 HeapWord* cur_addr = region_start + partial_obj_size;
380 size_t live_words = partial_obj_size;
381
382 while (true) {
383 assert(cur_addr < region_end, "inv");
384 cur_addr = PSParallelCompact::mark_bitmap()->find_obj_beg(cur_addr, region_end);
385 // There must be an overflowing obj in this region
386 assert(cur_addr < region_end, "inv");
387
388 oop obj = cast_to_oop(cur_addr);
389 size_t obj_size = obj->size();
390 if (destination + live_words + obj_size > target_end) {
391 // Found the overflowing obj
392 split_info.record(src_region, cur_addr, live_words);
393 *target_next = destination + live_words;
394 return cur_addr;
395 }
396
397 live_words += obj_size;
398 cur_addr += obj_size;
399 }
400 }
401
402 size_t ParallelCompactData::live_words_in_space(const MutableSpace* space,
403 HeapWord** full_region_prefix_end) {
404 size_t cur_region = addr_to_region_idx(space->bottom());
405 const size_t end_region = addr_to_region_idx(region_align_up(space->top()));
406 size_t live_words = 0;
407 if (full_region_prefix_end == nullptr) {
408 for (/* empty */; cur_region < end_region; ++cur_region) {
409 live_words += _region_data[cur_region].data_size();
410 }
411 } else {
412 bool first_set = false;
413 for (/* empty */; cur_region < end_region; ++cur_region) {
414 size_t live_words_in_region = _region_data[cur_region].data_size();
415 if (!first_set && live_words_in_region < RegionSize) {
416 *full_region_prefix_end = region_to_addr(cur_region);
417 first_set = true;
418 }
419 live_words += live_words_in_region;
420 }
421 if (!first_set) {
422 // All regions are full of live objs.
423 assert(is_region_aligned(space->top()), "inv");
424 *full_region_prefix_end = space->top();
425 }
426 assert(*full_region_prefix_end != nullptr, "postcondition");
427 assert(is_region_aligned(*full_region_prefix_end), "inv");
428 assert(*full_region_prefix_end >= space->bottom(), "in-range");
429 assert(*full_region_prefix_end <= space->top(), "in-range");
430 }
431 return live_words;
432 }
433
434 bool ParallelCompactData::summarize(SplitInfo& split_info,
435 HeapWord* source_beg, HeapWord* source_end,
436 HeapWord** source_next,
437 HeapWord* target_beg, HeapWord* target_end,
438 HeapWord** target_next)
439 {
440 HeapWord* const source_next_val = source_next == nullptr ? nullptr : *source_next;
441 log_develop_trace(gc, compaction)(
442 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
443 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
444 p2i(source_beg), p2i(source_end), p2i(source_next_val),
445 p2i(target_beg), p2i(target_end), p2i(*target_next));
446
447 size_t cur_region = addr_to_region_idx(source_beg);
448 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
449
450 HeapWord *dest_addr = target_beg;
451 for (/* empty */; cur_region < end_region; cur_region++) {
452 size_t words = _region_data[cur_region].data_size();
453
454 // Skip empty ones
455 if (words == 0) {
456 continue;
457 }
458
459 if (split_info.is_split(cur_region)) {
460 assert(words > split_info.preceding_live_words(), "inv");
461 words -= split_info.preceding_live_words();
462 }
463
464 _region_data[cur_region].set_destination(dest_addr);
465
466 // If cur_region does not fit entirely into the target space, find a point
467 // at which the source space can be 'split' so that part is copied to the
468 // target space and the rest is copied elsewhere.
469 if (dest_addr + words > target_end) {
470 assert(source_next != nullptr, "source_next is null when splitting");
471 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
472 target_end, target_next);
473 return false;
474 }
475
476 uint destination_count = split_info.is_split(cur_region)
477 ? split_info.preceding_destination_count()
478 : 0;
479
480 HeapWord* const last_addr = dest_addr + words - 1;
481 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
482 const size_t dest_region_2 = addr_to_region_idx(last_addr);
483
484 // Initially assume that the destination regions will be the same and
485 // adjust the value below if necessary. Under this assumption, if
486 // cur_region == dest_region_2, then cur_region will be compacted
487 // completely into itself.
488 destination_count += cur_region == dest_region_2 ? 0 : 1;
489 if (dest_region_1 != dest_region_2) {
490 // Destination regions differ; adjust destination_count.
491 destination_count += 1;
492 // Data from cur_region will be copied to the start of dest_region_2.
493 _region_data[dest_region_2].set_source_region(cur_region);
494 } else if (is_region_aligned(dest_addr)) {
495 // Data from cur_region will be copied to the start of the destination
496 // region.
497 _region_data[dest_region_1].set_source_region(cur_region);
498 }
499
500 _region_data[cur_region].set_destination_count(destination_count);
501 dest_addr += words;
502 }
503
504 *target_next = dest_addr;
505 return true;
506 }
507
508 #ifdef ASSERT
509 void ParallelCompactData::verify_clear() {
510 for (uint cur_idx = 0; cur_idx < region_count(); ++cur_idx) {
511 if (!region(cur_idx)->is_clear()) {
512 log_warning(gc)("Uncleared Region: %u", cur_idx);
513 region(cur_idx)->verify_clear();
514 }
515 }
516 }
517 #endif // #ifdef ASSERT
518
519 STWGCTimer PSParallelCompact::_gc_timer;
520 ParallelOldTracer PSParallelCompact::_gc_tracer;
521 elapsedTimer PSParallelCompact::_accumulated_time;
522 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
523 CollectorCounters* PSParallelCompact::_counters = nullptr;
524 ParMarkBitMap PSParallelCompact::_mark_bitmap;
525 ParallelCompactData PSParallelCompact::_summary_data;
526
527 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
528
529 class PCAdjustPointerClosure: public BasicOopIterateClosure {
530 template <typename T>
531 void do_oop_work(T* p) { PSParallelCompact::adjust_pointer(p); }
532
533 public:
534 virtual void do_oop(oop* p) { do_oop_work(p); }
535 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
536
537 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
538 };
539
540 static PCAdjustPointerClosure pc_adjust_pointer_closure;
541
542 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
543
544 void PSParallelCompact::post_initialize() {
545 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
546 _span_based_discoverer.set_span(heap->reserved_region());
547 _ref_processor =
548 new ReferenceProcessor(&_span_based_discoverer,
549 ParallelGCThreads, // mt processing degree
550 ParallelGCThreads, // mt discovery degree
551 false, // concurrent_discovery
552 &_is_alive_closure); // non-header is alive closure
553
554 _counters = new CollectorCounters("Parallel full collection pauses", 1);
555
556 // Initialize static fields in ParCompactionManager.
557 ParCompactionManager::initialize(mark_bitmap());
558 }
559
560 bool PSParallelCompact::initialize_aux_data() {
561 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
562 MemRegion mr = heap->reserved_region();
563 assert(mr.byte_size() != 0, "heap should be reserved");
564
565 initialize_space_info();
566
567 if (!_mark_bitmap.initialize(mr)) {
568 vm_shutdown_during_initialization(
569 err_msg("Unable to allocate %zuKB bitmaps for parallel "
570 "garbage collection for the requested %zuKB heap.",
571 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
572 return false;
573 }
574
575 if (!_summary_data.initialize(mr)) {
576 vm_shutdown_during_initialization(
577 err_msg("Unable to allocate %zuKB card tables for parallel "
578 "garbage collection for the requested %zuKB heap.",
579 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
580 return false;
581 }
582
583 return true;
584 }
585
586 void PSParallelCompact::initialize_space_info()
587 {
588 memset(&_space_info, 0, sizeof(_space_info));
589
590 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
591 PSYoungGen* young_gen = heap->young_gen();
592
593 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
594 _space_info[eden_space_id].set_space(young_gen->eden_space());
595 _space_info[from_space_id].set_space(young_gen->from_space());
596 _space_info[to_space_id].set_space(young_gen->to_space());
597
598 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
599 }
600
601 void
602 PSParallelCompact::clear_data_covering_space(SpaceId id)
603 {
604 // At this point, top is the value before GC, new_top() is the value that will
605 // be set at the end of GC. The marking bitmap is cleared to top; nothing
606 // should be marked above top. The summary data is cleared to the larger of
607 // top & new_top.
608 MutableSpace* const space = _space_info[id].space();
609 HeapWord* const bot = space->bottom();
610 HeapWord* const top = space->top();
611 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
612
613 _mark_bitmap.clear_range(bot, top);
614
615 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
616 const size_t end_region =
617 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
618 _summary_data.clear_range(beg_region, end_region);
619
620 // Clear the data used to 'split' regions.
621 SplitInfo& split_info = _space_info[id].split_info();
622 if (split_info.is_valid()) {
623 split_info.clear();
624 }
625 DEBUG_ONLY(split_info.verify_clear();)
626 }
627
628 void PSParallelCompact::pre_compact()
629 {
630 // Update the from & to space pointers in space_info, since they are swapped
631 // at each young gen gc. Do the update unconditionally (even though a
632 // promotion failure does not swap spaces) because an unknown number of young
633 // collections will have swapped the spaces an unknown number of times.
634 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
635 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
636 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
637 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
638
639 heap->increment_total_collections(true);
640
641 CodeCache::on_gc_marking_cycle_start();
642
643 heap->print_before_gc();
644 heap->trace_heap_before_gc(&_gc_tracer);
645
646 // Fill in TLABs
647 heap->ensure_parsability(true); // retire TLABs
648
649 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
650 Universe::verify("Before GC");
651 }
652
653 DEBUG_ONLY(mark_bitmap()->verify_clear();)
654 DEBUG_ONLY(summary_data().verify_clear();)
655 }
656
657 void PSParallelCompact::post_compact()
658 {
659 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
660 ParCompactionManager::remove_all_shadow_regions();
661
662 CodeCache::on_gc_marking_cycle_finish();
663 CodeCache::arm_all_nmethods();
664
665 // Need to clear claim bits for the next full-gc (marking and adjust-pointers).
666 ClassLoaderDataGraph::clear_claimed_marks();
667
668 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
669 // Clear the marking bitmap, summary data and split info.
670 clear_data_covering_space(SpaceId(id));
671 {
672 MutableSpace* space = _space_info[id].space();
673 HeapWord* top = space->top();
674 HeapWord* new_top = _space_info[id].new_top();
675 if (ZapUnusedHeapArea && new_top < top) {
676 space->mangle_region(MemRegion(new_top, top));
677 }
678 // Update top(). Must be done after clearing the bitmap and summary data.
679 space->set_top(new_top);
680 }
681 }
682
683 #ifdef ASSERT
684 {
685 mark_bitmap()->verify_clear();
686 summary_data().verify_clear();
687 }
688 #endif
689
690 ParCompactionManager::flush_all_string_dedup_requests();
691
692 MutableSpace* const eden_space = _space_info[eden_space_id].space();
693 MutableSpace* const from_space = _space_info[from_space_id].space();
694 MutableSpace* const to_space = _space_info[to_space_id].space();
695
696 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
697 bool eden_empty = eden_space->is_empty();
698
699 // Update heap occupancy information which is used as input to the soft ref
700 // clearing policy at the next gc.
701 Universe::heap()->update_capacity_and_used_at_gc();
702
703 bool young_gen_empty = eden_empty && from_space->is_empty() &&
704 to_space->is_empty();
705
706 PSCardTable* ct = heap->card_table();
707 MemRegion old_mr = heap->old_gen()->committed();
708 if (young_gen_empty) {
709 ct->clear_MemRegion(old_mr);
710 } else {
711 ct->dirty_MemRegion(old_mr);
712 }
713
714 heap->prune_scavengable_nmethods();
715
716 #if COMPILER2_OR_JVMCI
717 DerivedPointerTable::update_pointers();
718 #endif
719
720 // Signal that we have completed a visit to all live objects.
721 Universe::heap()->record_whole_heap_examined_timestamp();
722 }
723
724 HeapWord* PSParallelCompact::compute_dense_prefix_for_old_space(MutableSpace* old_space,
725 HeapWord* full_region_prefix_end) {
726 const size_t region_size = ParallelCompactData::RegionSize;
727 const ParallelCompactData& sd = summary_data();
728
729 // Iteration starts with the region *after* the full-region-prefix-end.
730 const RegionData* const start_region = sd.addr_to_region_ptr(full_region_prefix_end);
731 // If final region is not full, iteration stops before that region,
732 // because fill_dense_prefix_end assumes that prefix_end <= top.
733 const RegionData* const end_region = sd.addr_to_region_ptr(old_space->top());
734 assert(start_region <= end_region, "inv");
735
736 size_t max_waste = old_space->capacity_in_words() * (MarkSweepDeadRatio / 100.0);
737 const RegionData* cur_region = start_region;
738 for (/* empty */; cur_region < end_region; ++cur_region) {
739 assert(region_size >= cur_region->data_size(), "inv");
740 size_t dead_size = region_size - cur_region->data_size();
741 if (max_waste < dead_size) {
742 break;
743 }
744 max_waste -= dead_size;
745 }
746
747 HeapWord* const prefix_end = sd.region_to_addr(cur_region);
748 assert(sd.is_region_aligned(prefix_end), "postcondition");
749 assert(prefix_end >= full_region_prefix_end, "in-range");
750 assert(prefix_end <= old_space->top(), "in-range");
751 return prefix_end;
752 }
753
754 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) {
755 // Comparing two sizes to decide if filling is required:
756 //
757 // The size of the filler (min-obj-size) is 2 heap words with the default
758 // MinObjAlignment, since both markword and klass take 1 heap word.
759 // With +UseCompactObjectHeaders, the minimum filler size is only one word,
760 // because the Klass* gets encoded in the mark-word.
761 //
762 // The size of the gap (if any) right before dense-prefix-end is
763 // MinObjAlignment.
764 //
765 // Need to fill in the gap only if it's smaller than min-obj-size, and the
766 // filler obj will extend to next region.
767
768 if (MinObjAlignment >= checked_cast<int>(CollectedHeap::min_fill_size())) {
769 return;
770 }
771
772 assert(!UseCompactObjectHeaders, "Compact headers can allocate small objects");
773 assert(CollectedHeap::min_fill_size() == 2, "inv");
774 HeapWord* const dense_prefix_end = dense_prefix(id);
775 assert(_summary_data.is_region_aligned(dense_prefix_end), "precondition");
776 assert(dense_prefix_end <= space(id)->top(), "precondition");
777 if (dense_prefix_end == space(id)->top()) {
778 // Must not have single-word gap right before prefix-end/top.
779 return;
780 }
781 RegionData* const region_after_dense_prefix = _summary_data.addr_to_region_ptr(dense_prefix_end);
782
783 if (region_after_dense_prefix->partial_obj_size() != 0 ||
784 _mark_bitmap.is_marked(dense_prefix_end)) {
785 // The region after the dense prefix starts with live bytes.
786 return;
787 }
788
789 HeapWord* block_start = start_array(id)->block_start_reaching_into_card(dense_prefix_end);
790 if (block_start == dense_prefix_end - 1) {
791 assert(!_mark_bitmap.is_marked(block_start), "inv");
792 // There is exactly one heap word gap right before the dense prefix end, so we need a filler object.
793 // The filler object will extend into region_after_dense_prefix.
794 const size_t obj_len = 2; // min-fill-size
795 HeapWord* const obj_beg = dense_prefix_end - 1;
796 CollectedHeap::fill_with_object(obj_beg, obj_len);
797 _mark_bitmap.mark_obj(obj_beg);
798 _summary_data.addr_to_region_ptr(obj_beg)->add_live_obj(1);
799 region_after_dense_prefix->set_partial_obj_size(1);
800 region_after_dense_prefix->set_partial_obj_addr(obj_beg);
801 assert(start_array(id) != nullptr, "sanity");
802 start_array(id)->update_for_block(obj_beg, obj_beg + obj_len);
803 }
804 }
805
806 bool PSParallelCompact::check_maximum_compaction(bool should_do_max_compaction,
807 size_t total_live_words,
808 MutableSpace* const old_space,
809 HeapWord* full_region_prefix_end) {
810
811 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
812
813 // Check System.GC
814 bool is_max_on_system_gc = UseMaximumCompactionOnSystemGC
815 && GCCause::is_user_requested_gc(heap->gc_cause());
816
817 // Check if all live objs are too much for old-gen.
818 const bool is_old_gen_too_full = (total_live_words >= old_space->capacity_in_words());
819
820 // If all regions in old-gen are full
821 const bool is_region_full =
822 full_region_prefix_end >= _summary_data.region_align_down(old_space->top());
823
824 return should_do_max_compaction
825 || is_max_on_system_gc
826 || is_old_gen_too_full
827 || is_region_full;
828 }
829
830 void PSParallelCompact::summary_phase(bool should_do_max_compaction)
831 {
832 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
833
834 MutableSpace* const old_space = _space_info[old_space_id].space();
835 {
836 size_t total_live_words = 0;
837 HeapWord* full_region_prefix_end = nullptr;
838 {
839 // old-gen
840 size_t live_words = _summary_data.live_words_in_space(old_space,
841 &full_region_prefix_end);
842 total_live_words += live_words;
843 }
844 // young-gen
845 for (uint i = eden_space_id; i < last_space_id; ++i) {
846 const MutableSpace* space = _space_info[i].space();
847 size_t live_words = _summary_data.live_words_in_space(space);
848 total_live_words += live_words;
849 _space_info[i].set_new_top(space->bottom() + live_words);
850 _space_info[i].set_dense_prefix(space->bottom());
851 }
852
853 should_do_max_compaction = check_maximum_compaction(should_do_max_compaction,
854 total_live_words,
855 old_space,
856 full_region_prefix_end);
857 {
858 GCTraceTime(Info, gc, phases) tm("Summary Phase: expand", &_gc_timer);
859 // Try to expand old-gen in order to fit all live objs and waste.
860 size_t target_capacity_bytes = total_live_words * HeapWordSize
861 + old_space->capacity_in_bytes() * (MarkSweepDeadRatio / 100);
862 ParallelScavengeHeap::heap()->old_gen()->try_expand_till_size(target_capacity_bytes);
863 }
864
865 HeapWord* dense_prefix_end = should_do_max_compaction
866 ? full_region_prefix_end
867 : compute_dense_prefix_for_old_space(old_space,
868 full_region_prefix_end);
869 SpaceId id = old_space_id;
870 _space_info[id].set_dense_prefix(dense_prefix_end);
871
872 if (dense_prefix_end != old_space->bottom()) {
873 fill_dense_prefix_end(id);
874 }
875
876 // Compacting objs in [dense_prefix_end, old_space->top())
877 _summary_data.summarize(_space_info[id].split_info(),
878 dense_prefix_end, old_space->top(), nullptr,
879 dense_prefix_end, old_space->end(),
880 _space_info[id].new_top_addr());
881 }
882
883 // Summarize the remaining spaces in the young gen. The initial target space
884 // is the old gen. If a space does not fit entirely into the target, then the
885 // remainder is compacted into the space itself and that space becomes the new
886 // target.
887 SpaceId dst_space_id = old_space_id;
888 HeapWord* dst_space_end = old_space->end();
889 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
890 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
891 const MutableSpace* space = _space_info[id].space();
892 const size_t live = pointer_delta(_space_info[id].new_top(),
893 space->bottom());
894 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
895
896 if (live > 0 && live <= available) {
897 // All the live data will fit.
898 bool done = _summary_data.summarize(_space_info[id].split_info(),
899 space->bottom(), space->top(),
900 nullptr,
901 *new_top_addr, dst_space_end,
902 new_top_addr);
903 assert(done, "space must fit into old gen");
904
905 // Reset the new_top value for the space.
906 _space_info[id].set_new_top(space->bottom());
907 } else if (live > 0) {
908 // Attempt to fit part of the source space into the target space.
909 HeapWord* next_src_addr = nullptr;
910 bool done = _summary_data.summarize(_space_info[id].split_info(),
911 space->bottom(), space->top(),
912 &next_src_addr,
913 *new_top_addr, dst_space_end,
914 new_top_addr);
915 assert(!done, "space should not fit into old gen");
916 assert(next_src_addr != nullptr, "sanity");
917
918 // The source space becomes the new target, so the remainder is compacted
919 // within the space itself.
920 dst_space_id = SpaceId(id);
921 dst_space_end = space->end();
922 new_top_addr = _space_info[id].new_top_addr();
923 done = _summary_data.summarize(_space_info[id].split_info(),
924 next_src_addr, space->top(),
925 nullptr,
926 space->bottom(), dst_space_end,
927 new_top_addr);
928 assert(done, "space must fit when compacted into itself");
929 assert(*new_top_addr <= space->top(), "usage should not grow");
930 }
931 }
932 }
933
934 bool PSParallelCompact::invoke(bool clear_all_soft_refs, bool should_do_max_compaction) {
935 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
936 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
937 "should be in vm thread");
938 assert(ref_processor() != nullptr, "Sanity");
939
940 SvcGCMarker sgcm(SvcGCMarker::FULL);
941 IsSTWGCActiveMark mark;
942
943 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
944
945 GCIdMark gc_id_mark;
946 _gc_timer.register_gc_start();
947 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
948
949 GCCause::Cause gc_cause = heap->gc_cause();
950 PSOldGen* old_gen = heap->old_gen();
951 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
952
953 // Make sure data structures are sane, make the heap parsable, and do other
954 // miscellaneous bookkeeping.
955 pre_compact();
956
957 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
958
959 {
960 const uint active_workers =
961 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(),
962 ParallelScavengeHeap::heap()->workers().active_workers(),
963 Threads::number_of_non_daemon_threads());
964 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers);
965
966 GCTraceCPUTime tcpu(&_gc_tracer);
967 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause, true);
968
969 heap->pre_full_gc_dump(&_gc_timer);
970
971 TraceCollectorStats tcs(counters());
972 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause, "end of major GC");
973
974 if (log_is_enabled(Debug, gc, heap, exit)) {
975 accumulated_time()->start();
976 }
977
978 // Let the size policy know we're starting
979 size_policy->major_collection_begin();
980
981 #if COMPILER2_OR_JVMCI
982 DerivedPointerTable::clear();
983 #endif
984
985 ref_processor()->start_discovery(clear_all_soft_refs);
986
987 marking_phase(&_gc_tracer);
988
989 summary_phase(should_do_max_compaction);
990
991 #if COMPILER2_OR_JVMCI
992 assert(DerivedPointerTable::is_active(), "Sanity");
993 DerivedPointerTable::set_active(false);
994 #endif
995
996 forward_to_new_addr();
997
998 adjust_pointers();
999
1000 compact();
1001
1002 ParCompactionManager::_preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
1003
1004 ParCompactionManager::verify_all_region_stack_empty();
1005
1006 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1007 // done before resizing.
1008 post_compact();
1009
1010 size_policy->major_collection_end();
1011
1012 size_policy->sample_old_gen_used_bytes(MAX2(pre_gc_values.old_gen_used(), old_gen->used_in_bytes()));
1013
1014 if (UseAdaptiveSizePolicy) {
1015 heap->resize_after_full_gc();
1016 }
1017
1018 heap->resize_all_tlabs();
1019
1020 // Resize the metaspace capacity after a collection
1021 MetaspaceGC::compute_new_size();
1022
1023 if (log_is_enabled(Debug, gc, heap, exit)) {
1024 accumulated_time()->stop();
1025 }
1026
1027 heap->print_heap_change(pre_gc_values);
1028
1029 // Track memory usage and detect low memory
1030 MemoryService::track_memory_usage();
1031 heap->update_counters();
1032
1033 heap->post_full_gc_dump(&_gc_timer);
1034
1035 size_policy->record_gc_pause_end_instant();
1036 }
1037
1038 heap->gc_epilogue(true);
1039
1040 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1041 Universe::verify("After GC");
1042 }
1043
1044 heap->print_after_gc();
1045 heap->trace_heap_after_gc(&_gc_tracer);
1046
1047 _gc_timer.register_gc_end();
1048
1049 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1050 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1051
1052 return true;
1053 }
1054
1055 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1056 ParCompactionManager* _cm;
1057
1058 public:
1059 PCAddThreadRootsMarkingTaskClosure(ParCompactionManager* cm) : _cm(cm) { }
1060 void do_thread(Thread* thread) {
1061 ResourceMark rm;
1062
1063 MarkingNMethodClosure mark_and_push_in_blobs(&_cm->_mark_and_push_closure);
1064
1065 thread->oops_do(&_cm->_mark_and_push_closure, &mark_and_push_in_blobs);
1066
1067 // Do the real work
1068 _cm->follow_marking_stacks();
1069 }
1070 };
1071
1072 void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
1073 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1074
1075 ParCompactionManager* cm =
1076 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1077
1078 do {
1079 ScannerTask task;
1080 if (ParCompactionManager::steal(worker_id, task)) {
1081 cm->follow_contents(task, true);
1082 }
1083 cm->follow_marking_stacks();
1084 } while (!terminator.offer_termination());
1085 }
1086
1087 class MarkFromRootsTask : public WorkerTask {
1088 NMethodMarkingScope _nmethod_marking_scope;
1089 ThreadsClaimTokenScope _threads_claim_token_scope;
1090 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
1091 TaskTerminator _terminator;
1092 uint _active_workers;
1093
1094 public:
1095 MarkFromRootsTask(uint active_workers) :
1096 WorkerTask("MarkFromRootsTask"),
1097 _nmethod_marking_scope(),
1098 _threads_claim_token_scope(),
1099 _terminator(active_workers, ParCompactionManager::marking_stacks()),
1100 _active_workers(active_workers) {}
1101
1102 virtual void work(uint worker_id) {
1103 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1104 cm->create_marking_stats_cache();
1105 {
1106 CLDToOopClosure cld_closure(&cm->_mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
1107 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
1108
1109 // Do the real work
1110 cm->follow_marking_stacks();
1111 }
1112
1113 {
1114 PCAddThreadRootsMarkingTaskClosure closure(cm);
1115 Threads::possibly_parallel_threads_do(_active_workers > 1 /* is_par */, &closure);
1116 }
1117
1118 // Mark from OopStorages
1119 {
1120 _oop_storage_set_par_state.oops_do(&cm->_mark_and_push_closure);
1121 // Do the real work
1122 cm->follow_marking_stacks();
1123 }
1124
1125 if (_active_workers > 1) {
1126 steal_marking_work(_terminator, worker_id);
1127 }
1128 }
1129 };
1130
1131 class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
1132 TaskTerminator _terminator;
1133
1134 public:
1135 ParallelCompactRefProcProxyTask(uint max_workers)
1136 : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers),
1137 _terminator(_max_workers, ParCompactionManager::marking_stacks()) {}
1138
1139 void work(uint worker_id) override {
1140 assert(worker_id < _max_workers, "sanity");
1141 ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
1142 BarrierEnqueueDiscoveredFieldClosure enqueue;
1143 ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
1144 _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &cm->_mark_and_push_closure, &enqueue, &complete_gc);
1145 }
1146
1147 void prepare_run_task_hook() override {
1148 _terminator.reset_for_reuse(_queue_count);
1149 }
1150 };
1151
1152 static void flush_marking_stats_cache(const uint num_workers) {
1153 for (uint i = 0; i < num_workers; ++i) {
1154 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(i);
1155 cm->flush_and_destroy_marking_stats_cache();
1156 }
1157 }
1158
1159 void PSParallelCompact::marking_phase(ParallelOldTracer *gc_tracer) {
1160 // Recursively traverse all live objects and mark them
1161 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
1162
1163 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1164
1165 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
1166 {
1167 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
1168
1169 MarkFromRootsTask task(active_gc_threads);
1170 ParallelScavengeHeap::heap()->workers().run_task(&task);
1171 }
1172
1173 // Process reference objects found during marking
1174 {
1175 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
1176
1177 ReferenceProcessorStats stats;
1178 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
1179
1180 ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues());
1181 stats = ref_processor()->process_discovered_references(task, &ParallelScavengeHeap::heap()->workers(), pt);
1182
1183 gc_tracer->report_gc_reference_stats(stats);
1184 pt.print_all_references();
1185 }
1186
1187 {
1188 GCTraceTime(Debug, gc, phases) tm("Flush Marking Stats", &_gc_timer);
1189
1190 flush_marking_stats_cache(active_gc_threads);
1191 }
1192
1193 // This is the point where the entire marking should have completed.
1194 ParCompactionManager::verify_all_marking_stack_empty();
1195
1196 {
1197 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
1198 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(),
1199 is_alive_closure(),
1200 &do_nothing_cl,
1201 1);
1202 }
1203
1204 {
1205 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
1206
1207 ClassUnloadingContext ctx(1 /* num_nmethod_unlink_workers */,
1208 false /* unregister_nmethods_during_purge */,
1209 false /* lock_nmethod_free_separately */);
1210
1211 bool unloading_occurred;
1212 {
1213 CodeCache::UnlinkingScope scope(is_alive_closure());
1214
1215 // Follow system dictionary roots and unload classes.
1216 unloading_occurred = SystemDictionary::do_unloading(&_gc_timer);
1217
1218 // Unload nmethods.
1219 CodeCache::do_unloading(unloading_occurred);
1220 }
1221
1222 {
1223 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
1224 // Release unloaded nmethod's memory.
1225 ctx.purge_nmethods();
1226 }
1227 {
1228 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", &_gc_timer);
1229 ParallelScavengeHeap::heap()->prune_unlinked_nmethods();
1230 }
1231 {
1232 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
1233 ctx.free_nmethods();
1234 }
1235
1236 // Prune dead klasses from subklass/sibling/implementor lists.
1237 Klass::clean_weak_klass_links(unloading_occurred);
1238
1239 // Clean JVMCI metadata handles.
1240 JVMCI_ONLY(JVMCI::do_unloading(unloading_occurred));
1241 {
1242 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1243 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", gc_timer());
1244 ClassLoaderDataGraph::purge(true /* at_safepoint */);
1245 DEBUG_ONLY(MetaspaceUtils::verify();)
1246 }
1247 }
1248
1249 {
1250 GCTraceTime(Debug, gc, phases) tm("Report Object Count", &_gc_timer);
1251 _gc_tracer.report_object_count_after_gc(is_alive_closure(), &ParallelScavengeHeap::heap()->workers());
1252 }
1253 #if TASKQUEUE_STATS
1254 ParCompactionManager::print_and_reset_taskqueue_stats();
1255 #endif
1256 }
1257
1258 template<typename Func>
1259 void PSParallelCompact::adjust_in_space_helper(SpaceId id, volatile uint* claim_counter, Func&& on_stripe) {
1260 MutableSpace* sp = PSParallelCompact::space(id);
1261 HeapWord* const bottom = sp->bottom();
1262 HeapWord* const top = sp->top();
1263 if (bottom == top) {
1264 return;
1265 }
1266
1267 const uint num_regions_per_stripe = 2;
1268 const size_t region_size = ParallelCompactData::RegionSize;
1269 const size_t stripe_size = num_regions_per_stripe * region_size;
1270
1271 while (true) {
1272 uint counter = AtomicAccess::fetch_then_add(claim_counter, num_regions_per_stripe);
1273 HeapWord* cur_stripe = bottom + counter * region_size;
1274 if (cur_stripe >= top) {
1275 break;
1276 }
1277 HeapWord* stripe_end = MIN2(cur_stripe + stripe_size, top);
1278 on_stripe(cur_stripe, stripe_end);
1279 }
1280 }
1281
1282 void PSParallelCompact::adjust_in_old_space(volatile uint* claim_counter) {
1283 // Regions in old-space shouldn't be split.
1284 assert(!_space_info[old_space_id].split_info().is_valid(), "inv");
1285
1286 auto scan_obj_with_limit = [&] (HeapWord* obj_start, HeapWord* left, HeapWord* right) {
1287 assert(mark_bitmap()->is_marked(obj_start), "inv");
1288 oop obj = cast_to_oop(obj_start);
1289 return obj->oop_iterate_size(&pc_adjust_pointer_closure, MemRegion(left, right));
1290 };
1291
1292 adjust_in_space_helper(old_space_id, claim_counter, [&] (HeapWord* stripe_start, HeapWord* stripe_end) {
1293 assert(_summary_data.is_region_aligned(stripe_start), "inv");
1294 RegionData* cur_region = _summary_data.addr_to_region_ptr(stripe_start);
1295 HeapWord* obj_start;
1296 if (cur_region->partial_obj_size() != 0) {
1297 obj_start = cur_region->partial_obj_addr();
1298 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1299 } else {
1300 obj_start = stripe_start;
1301 }
1302
1303 while (obj_start < stripe_end) {
1304 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1305 if (obj_start >= stripe_end) {
1306 break;
1307 }
1308 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1309 }
1310 });
1311 }
1312
1313 void PSParallelCompact::adjust_in_young_space(SpaceId id, volatile uint* claim_counter) {
1314 adjust_in_space_helper(id, claim_counter, [](HeapWord* stripe_start, HeapWord* stripe_end) {
1315 HeapWord* obj_start = stripe_start;
1316 while (obj_start < stripe_end) {
1317 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1318 if (obj_start >= stripe_end) {
1319 break;
1320 }
1321 oop obj = cast_to_oop(obj_start);
1322 obj_start += obj->oop_iterate_size(&pc_adjust_pointer_closure);
1323 }
1324 });
1325 }
1326
1327 void PSParallelCompact::adjust_pointers_in_spaces(uint worker_id, volatile uint* claim_counters) {
1328 auto start_time = Ticks::now();
1329 adjust_in_old_space(&claim_counters[0]);
1330 for (uint id = eden_space_id; id < last_space_id; ++id) {
1331 adjust_in_young_space(SpaceId(id), &claim_counters[id]);
1332 }
1333 log_trace(gc, phases)("adjust_pointers_in_spaces worker %u: %.3f ms", worker_id, (Ticks::now() - start_time).seconds() * 1000);
1334 }
1335
1336 class PSAdjustTask final : public WorkerTask {
1337 SubTasksDone _sub_tasks;
1338 WeakProcessor::Task _weak_proc_task;
1339 OopStorageSetStrongParState<false, false> _oop_storage_iter;
1340 uint _nworkers;
1341 volatile uint _claim_counters[PSParallelCompact::last_space_id] = {};
1342
1343 enum PSAdjustSubTask {
1344 PSAdjustSubTask_code_cache,
1345
1346 PSAdjustSubTask_num_elements
1347 };
1348
1349 public:
1350 PSAdjustTask(uint nworkers) :
1351 WorkerTask("PSAdjust task"),
1352 _sub_tasks(PSAdjustSubTask_num_elements),
1353 _weak_proc_task(nworkers),
1354 _nworkers(nworkers) {
1355
1356 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
1357 Threads::change_thread_claim_token();
1358 }
1359
1360 ~PSAdjustTask() {
1361 Threads::assert_all_threads_claimed();
1362 }
1363
1364 void work(uint worker_id) {
1365 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1366 cm->preserved_marks()->adjust_during_full_gc();
1367 {
1368 // adjust pointers in all spaces
1369 PSParallelCompact::adjust_pointers_in_spaces(worker_id, _claim_counters);
1370 }
1371 {
1372 ResourceMark rm;
1373 Threads::possibly_parallel_oops_do(_nworkers > 1, &pc_adjust_pointer_closure, nullptr);
1374 }
1375 _oop_storage_iter.oops_do(&pc_adjust_pointer_closure);
1376 {
1377 CLDToOopClosure cld_closure(&pc_adjust_pointer_closure, ClassLoaderData::_claim_stw_fullgc_adjust);
1378 ClassLoaderDataGraph::cld_do(&cld_closure);
1379 }
1380 {
1381 AlwaysTrueClosure always_alive;
1382 _weak_proc_task.work(worker_id, &always_alive, &pc_adjust_pointer_closure);
1383 }
1384 if (_sub_tasks.try_claim_task(PSAdjustSubTask_code_cache)) {
1385 NMethodToOopClosure adjust_code(&pc_adjust_pointer_closure, NMethodToOopClosure::FixRelocations);
1386 CodeCache::nmethods_do(&adjust_code);
1387 }
1388 _sub_tasks.all_tasks_claimed();
1389 }
1390 };
1391
1392 void PSParallelCompact::adjust_pointers() {
1393 // Adjust the pointers to reflect the new locations
1394 GCTraceTime(Info, gc, phases) tm("Adjust Pointers", &_gc_timer);
1395 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1396 PSAdjustTask task(nworkers);
1397 ParallelScavengeHeap::heap()->workers().run_task(&task);
1398 }
1399
1400 // Split [start, end) evenly for a number of workers and return the
1401 // range for worker_id.
1402 static void split_regions_for_worker(size_t start, size_t end,
1403 uint worker_id, uint num_workers,
1404 size_t* worker_start, size_t* worker_end) {
1405 assert(start < end, "precondition");
1406 assert(num_workers > 0, "precondition");
1407 assert(worker_id < num_workers, "precondition");
1408
1409 size_t num_regions = end - start;
1410 size_t num_regions_per_worker = num_regions / num_workers;
1411 size_t remainder = num_regions % num_workers;
1412 // The first few workers will get one extra.
1413 *worker_start = start + worker_id * num_regions_per_worker
1414 + MIN2(checked_cast<size_t>(worker_id), remainder);
1415 *worker_end = *worker_start + num_regions_per_worker
1416 + (worker_id < remainder ? 1 : 0);
1417 }
1418
1419 void PSParallelCompact::forward_to_new_addr() {
1420 GCTraceTime(Info, gc, phases) tm("Forward", &_gc_timer);
1421 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1422
1423 struct ForwardTask final : public WorkerTask {
1424 uint _num_workers;
1425
1426 explicit ForwardTask(uint num_workers) :
1427 WorkerTask("PSForward task"),
1428 _num_workers(num_workers) {}
1429
1430 static void forward_objs_in_range(ParCompactionManager* cm,
1431 HeapWord* start,
1432 HeapWord* end,
1433 HeapWord* destination) {
1434 HeapWord* cur_addr = start;
1435 HeapWord* new_addr = destination;
1436
1437 while (cur_addr < end) {
1438 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, end);
1439 if (cur_addr >= end) {
1440 return;
1441 }
1442 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1443 oop obj = cast_to_oop(cur_addr);
1444 if (new_addr != cur_addr) {
1445 cm->preserved_marks()->push_if_necessary(obj, obj->mark());
1446 FullGCForwarding::forward_to(obj, cast_to_oop(new_addr));
1447 }
1448 size_t obj_size = obj->size();
1449 new_addr += obj_size;
1450 cur_addr += obj_size;
1451 }
1452 }
1453
1454 void work(uint worker_id) override {
1455 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1456 for (uint id = old_space_id; id < last_space_id; ++id) {
1457 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1458 HeapWord* dense_prefix_addr = dense_prefix(SpaceId(id));
1459 HeapWord* top = sp->top();
1460
1461 if (dense_prefix_addr == top) {
1462 // Empty space
1463 continue;
1464 }
1465
1466 const SplitInfo& split_info = _space_info[SpaceId(id)].split_info();
1467 size_t dense_prefix_region = _summary_data.addr_to_region_idx(dense_prefix_addr);
1468 size_t top_region = _summary_data.addr_to_region_idx(_summary_data.region_align_up(top));
1469 size_t start_region;
1470 size_t end_region;
1471 split_regions_for_worker(dense_prefix_region, top_region,
1472 worker_id, _num_workers,
1473 &start_region, &end_region);
1474 for (size_t cur_region = start_region; cur_region < end_region; ++cur_region) {
1475 RegionData* region_ptr = _summary_data.region(cur_region);
1476 size_t partial_obj_size = region_ptr->partial_obj_size();
1477
1478 if (partial_obj_size == ParallelCompactData::RegionSize) {
1479 // No obj-start
1480 continue;
1481 }
1482
1483 HeapWord* region_start = _summary_data.region_to_addr(cur_region);
1484 HeapWord* region_end = region_start + ParallelCompactData::RegionSize;
1485
1486 if (split_info.is_split(cur_region)) {
1487 // Part 1: will be relocated to space-1
1488 HeapWord* preceding_destination = split_info.preceding_destination();
1489 HeapWord* split_point = split_info.split_point();
1490 forward_objs_in_range(cm, region_start + partial_obj_size, split_point, preceding_destination + partial_obj_size);
1491
1492 // Part 2: will be relocated to space-2
1493 HeapWord* destination = region_ptr->destination();
1494 forward_objs_in_range(cm, split_point, region_end, destination);
1495 } else {
1496 HeapWord* destination = region_ptr->destination();
1497 forward_objs_in_range(cm, region_start + partial_obj_size, region_end, destination + partial_obj_size);
1498 }
1499 }
1500 }
1501 }
1502 } task(nworkers);
1503
1504 ParallelScavengeHeap::heap()->workers().run_task(&task);
1505 DEBUG_ONLY(verify_forward();)
1506 }
1507
1508 #ifdef ASSERT
1509 void PSParallelCompact::verify_forward() {
1510 HeapWord* const old_dense_prefix_addr = dense_prefix(SpaceId(old_space_id));
1511 // The destination addr for the first live obj after dense-prefix.
1512 HeapWord* bump_ptr = old_dense_prefix_addr
1513 + _summary_data.addr_to_region_ptr(old_dense_prefix_addr)->partial_obj_size();
1514 SpaceId bump_ptr_space = old_space_id;
1515
1516 for (uint id = old_space_id; id < last_space_id; ++id) {
1517 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1518 // Only verify objs after dense-prefix, because those before dense-prefix are not moved (forwarded).
1519 HeapWord* cur_addr = dense_prefix(SpaceId(id));
1520 HeapWord* top = sp->top();
1521
1522 while (cur_addr < top) {
1523 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, top);
1524 if (cur_addr >= top) {
1525 break;
1526 }
1527 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1528 assert(bump_ptr <= _space_info[bump_ptr_space].new_top(), "inv");
1529 // Move to the space containing cur_addr
1530 if (bump_ptr == _space_info[bump_ptr_space].new_top()) {
1531 bump_ptr = space(space_id(cur_addr))->bottom();
1532 bump_ptr_space = space_id(bump_ptr);
1533 }
1534 oop obj = cast_to_oop(cur_addr);
1535 if (cur_addr == bump_ptr) {
1536 assert(!FullGCForwarding::is_forwarded(obj), "inv");
1537 } else {
1538 assert(FullGCForwarding::forwardee(obj) == cast_to_oop(bump_ptr), "inv");
1539 }
1540 bump_ptr += obj->size();
1541 cur_addr += obj->size();
1542 }
1543 }
1544 }
1545 #endif
1546
1547 // Helper class to print 8 region numbers per line and then print the total at the end.
1548 class FillableRegionLogger : public StackObj {
1549 private:
1550 Log(gc, compaction) log;
1551 static const int LineLength = 8;
1552 size_t _regions[LineLength];
1553 int _next_index;
1554 bool _enabled;
1555 size_t _total_regions;
1556 public:
1557 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
1558 ~FillableRegionLogger() {
1559 log.trace("%zu initially fillable regions", _total_regions);
1560 }
1561
1562 void print_line() {
1563 if (!_enabled || _next_index == 0) {
1564 return;
1565 }
1566 FormatBuffer<> line("Fillable: ");
1567 for (int i = 0; i < _next_index; i++) {
1568 line.append(" %7zu", _regions[i]);
1569 }
1570 log.trace("%s", line.buffer());
1571 _next_index = 0;
1572 }
1573
1574 void handle(size_t region) {
1575 if (!_enabled) {
1576 return;
1577 }
1578 _regions[_next_index++] = region;
1579 if (_next_index == LineLength) {
1580 print_line();
1581 }
1582 _total_regions++;
1583 }
1584 };
1585
1586 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
1587 {
1588 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
1589
1590 // Find the threads that are active
1591 uint worker_id = 0;
1592
1593 // Find all regions that are available (can be filled immediately) and
1594 // distribute them to the thread stacks. The iteration is done in reverse
1595 // order (high to low) so the regions will be removed in ascending order.
1596
1597 const ParallelCompactData& sd = PSParallelCompact::summary_data();
1598
1599 // id + 1 is used to test termination so unsigned can
1600 // be used with an old_space_id == 0.
1601 FillableRegionLogger region_logger;
1602 for (unsigned int id = last_space_id - 1; id + 1 > old_space_id; --id) {
1603 SpaceInfo* const space_info = _space_info + id;
1604 HeapWord* const new_top = space_info->new_top();
1605
1606 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
1607 const size_t end_region =
1608 sd.addr_to_region_idx(sd.region_align_up(new_top));
1609
1610 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
1611 if (sd.region(cur)->claim_unsafe()) {
1612 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1613 bool result = sd.region(cur)->mark_normal();
1614 assert(result, "Must succeed at this point.");
1615 cm->region_stack()->push(cur);
1616 region_logger.handle(cur);
1617 // Assign regions to tasks in round-robin fashion.
1618 if (++worker_id == parallel_gc_threads) {
1619 worker_id = 0;
1620 }
1621 }
1622 }
1623 region_logger.print_line();
1624 }
1625 }
1626
1627 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
1628 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1629
1630 ParCompactionManager* cm =
1631 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1632
1633 // Drain the stacks that have been preloaded with regions
1634 // that are ready to fill.
1635
1636 cm->drain_region_stacks();
1637
1638 guarantee(cm->region_stack()->is_empty(), "Not empty");
1639
1640 size_t region_index = 0;
1641
1642 while (true) {
1643 if (ParCompactionManager::steal(worker_id, region_index)) {
1644 PSParallelCompact::fill_and_update_region(cm, region_index);
1645 cm->drain_region_stacks();
1646 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
1647 // Fill and update an unavailable region with the help of a shadow region
1648 PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
1649 cm->drain_region_stacks();
1650 } else {
1651 if (terminator->offer_termination()) {
1652 break;
1653 }
1654 // Go around again.
1655 }
1656 }
1657 }
1658
1659 class FillDensePrefixAndCompactionTask: public WorkerTask {
1660 TaskTerminator _terminator;
1661
1662 public:
1663 FillDensePrefixAndCompactionTask(uint active_workers) :
1664 WorkerTask("FillDensePrefixAndCompactionTask"),
1665 _terminator(active_workers, ParCompactionManager::region_task_queues()) {
1666 }
1667
1668 virtual void work(uint worker_id) {
1669 if (worker_id == 0) {
1670 auto start = Ticks::now();
1671 PSParallelCompact::fill_dead_objs_in_dense_prefix();
1672 log_trace(gc, phases)("Fill dense prefix by worker 0: %.3f ms", (Ticks::now() - start).seconds() * 1000);
1673 }
1674 compaction_with_stealing_work(&_terminator, worker_id);
1675 }
1676 };
1677
1678 void PSParallelCompact::fill_range_in_dense_prefix(HeapWord* start, HeapWord* end) {
1679 #ifdef ASSERT
1680 {
1681 assert(start < end, "precondition");
1682 assert(mark_bitmap()->find_obj_beg(start, end) == end, "precondition");
1683 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1684 if (start != bottom) {
1685 // The preceding live obj.
1686 HeapWord* obj_start = mark_bitmap()->find_obj_beg_reverse(bottom, start);
1687 HeapWord* obj_end = obj_start + cast_to_oop(obj_start)->size();
1688 assert(obj_end == start, "precondition");
1689 }
1690 }
1691 #endif
1692
1693 CollectedHeap::fill_with_objects(start, pointer_delta(end, start));
1694 HeapWord* addr = start;
1695 do {
1696 size_t size = cast_to_oop(addr)->size();
1697 start_array(old_space_id)->update_for_block(addr, addr + size);
1698 addr += size;
1699 } while (addr < end);
1700 }
1701
1702 void PSParallelCompact::fill_dead_objs_in_dense_prefix() {
1703 ParMarkBitMap* bitmap = mark_bitmap();
1704
1705 HeapWord* const bottom = _space_info[old_space_id].space()->bottom();
1706 HeapWord* const prefix_end = dense_prefix(old_space_id);
1707
1708 const size_t region_size = ParallelCompactData::RegionSize;
1709
1710 // Fill dead space in [start_addr, end_addr)
1711 HeapWord* const start_addr = bottom;
1712 HeapWord* const end_addr = prefix_end;
1713
1714 for (HeapWord* cur_addr = start_addr; cur_addr < end_addr; /* empty */) {
1715 RegionData* cur_region_ptr = _summary_data.addr_to_region_ptr(cur_addr);
1716 if (cur_region_ptr->data_size() == region_size) {
1717 // Full; no dead space. Next region.
1718 if (_summary_data.is_region_aligned(cur_addr)) {
1719 cur_addr += region_size;
1720 } else {
1721 cur_addr = _summary_data.region_align_up(cur_addr);
1722 }
1723 continue;
1724 }
1725
1726 // Fill dead space inside cur_region.
1727 if (_summary_data.is_region_aligned(cur_addr)) {
1728 cur_addr += cur_region_ptr->partial_obj_size();
1729 }
1730
1731 HeapWord* region_end_addr = _summary_data.region_align_up(cur_addr + 1);
1732 assert(region_end_addr <= end_addr, "inv");
1733 while (cur_addr < region_end_addr) {
1734 // Use end_addr to allow filler-obj to cross region boundary.
1735 HeapWord* live_start = bitmap->find_obj_beg(cur_addr, end_addr);
1736 if (cur_addr != live_start) {
1737 // Found dead space [cur_addr, live_start).
1738 fill_range_in_dense_prefix(cur_addr, live_start);
1739 }
1740 if (live_start >= region_end_addr) {
1741 cur_addr = live_start;
1742 break;
1743 }
1744 assert(bitmap->is_marked(live_start), "inv");
1745 cur_addr = live_start + cast_to_oop(live_start)->size();
1746 }
1747 }
1748 }
1749
1750 void PSParallelCompact::compact() {
1751 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
1752
1753 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1754
1755 initialize_shadow_regions(active_gc_threads);
1756 prepare_region_draining_tasks(active_gc_threads);
1757
1758 {
1759 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
1760
1761 FillDensePrefixAndCompactionTask task(active_gc_threads);
1762 ParallelScavengeHeap::heap()->workers().run_task(&task);
1763
1764 #ifdef ASSERT
1765 verify_filler_in_dense_prefix();
1766
1767 // Verify that all regions have been processed.
1768 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1769 verify_complete(SpaceId(id));
1770 }
1771 #endif
1772 }
1773 }
1774
1775 #ifdef ASSERT
1776 void PSParallelCompact::verify_filler_in_dense_prefix() {
1777 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1778 HeapWord* dense_prefix_end = dense_prefix(old_space_id);
1779
1780 const size_t region_size = ParallelCompactData::RegionSize;
1781
1782 for (HeapWord* cur_addr = bottom; cur_addr < dense_prefix_end; /* empty */) {
1783 RegionData* cur_region_ptr = _summary_data.addr_to_region_ptr(cur_addr);
1784 if (cur_region_ptr->data_size() == region_size) {
1785 // Full; no dead space. Next region.
1786 if (_summary_data.is_region_aligned(cur_addr)) {
1787 cur_addr += region_size;
1788 } else {
1789 cur_addr = _summary_data.region_align_up(cur_addr);
1790 }
1791 continue;
1792 }
1793
1794 // This region contains filler objs.
1795 if (_summary_data.is_region_aligned(cur_addr)) {
1796 cur_addr += cur_region_ptr->partial_obj_size();
1797 }
1798
1799 HeapWord* region_end_addr = _summary_data.region_align_up(cur_addr + 1);
1800 assert(region_end_addr <= dense_prefix_end, "inv");
1801
1802 while (cur_addr < region_end_addr) {
1803 oop obj = cast_to_oop(cur_addr);
1804 oopDesc::verify(obj);
1805 if (!mark_bitmap()->is_marked(cur_addr)) {
1806 Klass* k = cast_to_oop(cur_addr)->klass();
1807 assert(k == Universe::fillerArrayKlass() || k == vmClasses::FillerObject_klass(), "inv");
1808 }
1809 cur_addr += obj->size();
1810 }
1811 }
1812 }
1813
1814 void PSParallelCompact::verify_complete(SpaceId space_id) {
1815 // All Regions served as compaction targets, from dense_prefix() to
1816 // new_top(), should be marked as filled and all Regions between new_top()
1817 // and top() should be available (i.e., should have been emptied).
1818 ParallelCompactData& sd = summary_data();
1819 SpaceInfo si = _space_info[space_id];
1820 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
1821 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
1822 const size_t beg_region = sd.addr_to_region_idx(si.dense_prefix());
1823 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
1824 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
1825
1826 size_t cur_region;
1827 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
1828 const RegionData* const c = sd.region(cur_region);
1829 assert(c->completed(), "region %zu not filled: destination_count=%u",
1830 cur_region, c->destination_count());
1831 }
1832
1833 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
1834 const RegionData* const c = sd.region(cur_region);
1835 assert(c->available(), "region %zu not empty: destination_count=%u",
1836 cur_region, c->destination_count());
1837 }
1838 }
1839 #endif // #ifdef ASSERT
1840
1841 // Return the SpaceId for the space containing addr. If addr is not in the
1842 // heap, last_space_id is returned. In debug mode it expects the address to be
1843 // in the heap and asserts such.
1844 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
1845 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
1846
1847 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1848 if (_space_info[id].space()->contains(addr)) {
1849 return SpaceId(id);
1850 }
1851 }
1852
1853 assert(false, "no space contains the addr");
1854 return last_space_id;
1855 }
1856
1857 // Skip over count live words starting from beg, and return the address of the
1858 // next live word. Callers must also ensure that there are enough live words in
1859 // the range [beg, end) to skip.
1860 HeapWord* PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
1861 {
1862 ParMarkBitMap* m = mark_bitmap();
1863 HeapWord* cur_addr = beg;
1864 while (true) {
1865 cur_addr = m->find_obj_beg(cur_addr, end);
1866 assert(cur_addr < end, "inv");
1867 size_t obj_size = cast_to_oop(cur_addr)->size();
1868 // Strictly greater-than
1869 if (obj_size > count) {
1870 return cur_addr + count;
1871 }
1872 count -= obj_size;
1873 cur_addr += obj_size;
1874 }
1875 }
1876
1877 // On starting to fill a destination region (dest-region), we need to know the
1878 // location of the word that will be at the start of the dest-region after
1879 // compaction. A dest-region can have one or more source regions, but only the
1880 // first source-region contains this location. This location is retrieved by
1881 // calling `first_src_addr` on a dest-region.
1882 // Conversely, a source-region has a dest-region which holds the destination of
1883 // the first live word on this source-region, based on which the destination
1884 // for the rest of live words can be derived.
1885 //
1886 // Note:
1887 // There is some complication due to space-boundary-fragmentation (an obj can't
1888 // cross space-boundary) -- a source-region may be split and behave like two
1889 // distinct regions with their own dest-region, as depicted below.
1890 //
1891 // source-region: region-n
1892 //
1893 // **********************
1894 // | A|A~~~~B|B |
1895 // **********************
1896 // n-1 n n+1
1897 //
1898 // AA, BB denote two live objs. ~~~~ denotes unknown number of live objs.
1899 //
1900 // Assuming the dest-region for region-n is the final region before
1901 // old-space-end and its first-live-word is the middle of AA, the heap content
1902 // will look like the following after compaction:
1903 //
1904 // ************** *************
1905 // A|A~~~~ | |BB |
1906 // ************** *************
1907 // ^ ^
1908 // | old-space-end | eden-space-start
1909 //
1910 // Therefore, in this example, region-n will have two dest-regions:
1911 // 1. the final region in old-space
1912 // 2. the first region in eden-space.
1913 // To handle this special case, we introduce the concept of split-region, whose
1914 // contents are relocated to two spaces. `SplitInfo` captures all necessary
1915 // info about the split, the first part, spliting-point, and the second part.
1916 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
1917 SpaceId src_space_id,
1918 size_t src_region_idx)
1919 {
1920 const size_t RegionSize = ParallelCompactData::RegionSize;
1921 const ParallelCompactData& sd = summary_data();
1922 assert(sd.is_region_aligned(dest_addr), "precondition");
1923
1924 const RegionData* const src_region_ptr = sd.region(src_region_idx);
1925 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
1926
1927 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
1928 HeapWord* const src_region_destination = src_region_ptr->destination();
1929
1930 HeapWord* const region_start = sd.region_to_addr(src_region_idx);
1931 HeapWord* const region_end = sd.region_to_addr(src_region_idx) + RegionSize;
1932
1933 // Identify the actual destination for the first live words on this region,
1934 // taking split-region into account.
1935 HeapWord* region_start_destination;
1936 const SplitInfo& split_info = _space_info[src_space_id].split_info();
1937 if (split_info.is_split(src_region_idx)) {
1938 // The second part of this split region; use the recorded split point.
1939 if (dest_addr == src_region_destination) {
1940 return split_info.split_point();
1941 }
1942 region_start_destination = split_info.preceding_destination();
1943 } else {
1944 region_start_destination = src_region_destination;
1945 }
1946
1947 // Calculate the offset to be skipped
1948 size_t words_to_skip = pointer_delta(dest_addr, region_start_destination);
1949
1950 HeapWord* result;
1951 if (partial_obj_size > words_to_skip) {
1952 result = region_start + words_to_skip;
1953 } else {
1954 words_to_skip -= partial_obj_size;
1955 result = skip_live_words(region_start + partial_obj_size, region_end, words_to_skip);
1956 }
1957
1958 if (split_info.is_split(src_region_idx)) {
1959 assert(result < split_info.split_point(), "postcondition");
1960 } else {
1961 assert(result < region_end, "postcondition");
1962 }
1963
1964 return result;
1965 }
1966
1967 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
1968 SpaceId src_space_id,
1969 size_t beg_region,
1970 HeapWord* end_addr)
1971 {
1972 ParallelCompactData& sd = summary_data();
1973
1974 #ifdef ASSERT
1975 MutableSpace* const src_space = _space_info[src_space_id].space();
1976 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
1977 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
1978 "src_space_id does not match beg_addr");
1979 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
1980 "src_space_id does not match end_addr");
1981 #endif // #ifdef ASSERT
1982
1983 RegionData* const beg = sd.region(beg_region);
1984 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
1985
1986 // Regions up to new_top() are enqueued if they become available.
1987 HeapWord* const new_top = _space_info[src_space_id].new_top();
1988 RegionData* const enqueue_end =
1989 sd.addr_to_region_ptr(sd.region_align_up(new_top));
1990
1991 for (RegionData* cur = beg; cur < end; ++cur) {
1992 assert(cur->data_size() > 0, "region must have live data");
1993 cur->decrement_destination_count();
1994 if (cur < enqueue_end && cur->available() && cur->claim()) {
1995 if (cur->mark_normal()) {
1996 cm->push_region(sd.region(cur));
1997 } else if (cur->mark_copied()) {
1998 // Try to copy the content of the shadow region back to its corresponding
1999 // heap region if the shadow region is filled. Otherwise, the GC thread
2000 // fills the shadow region will copy the data back (see
2001 // MoveAndUpdateShadowClosure::complete_region).
2002 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2003 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2004 cur->set_completed();
2005 }
2006 }
2007 }
2008 }
2009
2010 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2011 SpaceId& src_space_id,
2012 HeapWord*& src_space_top,
2013 HeapWord* end_addr)
2014 {
2015 ParallelCompactData& sd = PSParallelCompact::summary_data();
2016
2017 size_t src_region_idx = 0;
2018
2019 // Skip empty regions (if any) up to the top of the space.
2020 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2021 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2022 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2023 const RegionData* const top_region_ptr = sd.addr_to_region_ptr(top_aligned_up);
2024
2025 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2026 ++src_region_ptr;
2027 }
2028
2029 if (src_region_ptr < top_region_ptr) {
2030 // Found the first non-empty region in the same space.
2031 src_region_idx = sd.region(src_region_ptr);
2032 closure.set_source(sd.region_to_addr(src_region_idx));
2033 return src_region_idx;
2034 }
2035
2036 // Switch to a new source space and find the first non-empty region.
2037 uint space_id = src_space_id + 1;
2038 assert(space_id < last_space_id, "not enough spaces");
2039
2040 for (/* empty */; space_id < last_space_id; ++space_id) {
2041 HeapWord* bottom = _space_info[space_id].space()->bottom();
2042 HeapWord* top = _space_info[space_id].space()->top();
2043 // Skip empty space
2044 if (bottom == top) {
2045 continue;
2046 }
2047
2048 // Identify the first region that contains live words in this space
2049 size_t cur_region = sd.addr_to_region_idx(bottom);
2050 size_t end_region = sd.addr_to_region_idx(sd.region_align_up(top));
2051
2052 for (/* empty */ ; cur_region < end_region; ++cur_region) {
2053 RegionData* cur = sd.region(cur_region);
2054 if (cur->live_obj_size() > 0) {
2055 HeapWord* region_start_addr = sd.region_to_addr(cur_region);
2056
2057 src_space_id = SpaceId(space_id);
2058 src_space_top = top;
2059 closure.set_source(region_start_addr);
2060 return cur_region;
2061 }
2062 }
2063 }
2064
2065 ShouldNotReachHere();
2066 }
2067
2068 HeapWord* PSParallelCompact::partial_obj_end(HeapWord* region_start_addr) {
2069 ParallelCompactData& sd = summary_data();
2070 assert(sd.is_region_aligned(region_start_addr), "precondition");
2071
2072 // Use per-region partial_obj_size to locate the end of the obj, that extends
2073 // to region_start_addr.
2074 size_t start_region_idx = sd.addr_to_region_idx(region_start_addr);
2075 size_t end_region_idx = sd.region_count();
2076 size_t accumulated_size = 0;
2077 for (size_t region_idx = start_region_idx; region_idx < end_region_idx; ++region_idx) {
2078 size_t cur_partial_obj_size = sd.region(region_idx)->partial_obj_size();
2079 accumulated_size += cur_partial_obj_size;
2080 if (cur_partial_obj_size != ParallelCompactData::RegionSize) {
2081 break;
2082 }
2083 }
2084 return region_start_addr + accumulated_size;
2085 }
2086
2087 // Use region_idx as the destination region, and evacuate all live objs on its
2088 // source regions to this destination region.
2089 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2090 {
2091 ParMarkBitMap* const bitmap = mark_bitmap();
2092 ParallelCompactData& sd = summary_data();
2093 RegionData* const region_ptr = sd.region(region_idx);
2094
2095 // Get the source region and related info.
2096 size_t src_region_idx = region_ptr->source_region();
2097 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2098 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2099 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2100
2101 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2102
2103 // Adjust src_region_idx to prepare for decrementing destination counts (the
2104 // destination count is not decremented when a region is copied to itself).
2105 if (src_region_idx == region_idx) {
2106 src_region_idx += 1;
2107 }
2108
2109 // source-region:
2110 //
2111 // **********
2112 // | ~~~ |
2113 // **********
2114 // ^
2115 // |-- closure.source() / first_src_addr
2116 //
2117 //
2118 // ~~~ : live words
2119 //
2120 // destination-region:
2121 //
2122 // **********
2123 // | |
2124 // **********
2125 // ^
2126 // |-- region-start
2127 if (bitmap->is_unmarked(closure.source())) {
2128 // An object overflows the previous destination region, so this
2129 // destination region should copy the remainder of the object or as much as
2130 // will fit.
2131 HeapWord* const old_src_addr = closure.source();
2132 {
2133 HeapWord* region_start = sd.region_align_down(closure.source());
2134 HeapWord* obj_start = bitmap->find_obj_beg_reverse(region_start, closure.source());
2135 HeapWord* obj_end;
2136 if (obj_start != closure.source()) {
2137 assert(bitmap->is_marked(obj_start), "inv");
2138 // Found the actual obj-start, try to find the obj-end using either
2139 // size() if this obj is completely contained in the current region.
2140 HeapWord* next_region_start = region_start + ParallelCompactData::RegionSize;
2141 HeapWord* partial_obj_start = (next_region_start >= src_space_top)
2142 ? nullptr
2143 : sd.addr_to_region_ptr(next_region_start)->partial_obj_addr();
2144 // This obj extends to next region iff partial_obj_addr of the *next*
2145 // region is the same as obj-start.
2146 if (partial_obj_start == obj_start) {
2147 // This obj extends to next region.
2148 obj_end = partial_obj_end(next_region_start);
2149 } else {
2150 // Completely contained in this region; safe to use size().
2151 obj_end = obj_start + cast_to_oop(obj_start)->size();
2152 }
2153 } else {
2154 // This obj extends to current region.
2155 obj_end = partial_obj_end(region_start);
2156 }
2157 size_t partial_obj_size = pointer_delta(obj_end, closure.source());
2158 closure.copy_partial_obj(partial_obj_size);
2159 }
2160
2161 if (closure.is_full()) {
2162 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2163 closure.complete_region(dest_addr, region_ptr);
2164 return;
2165 }
2166
2167 // Finished copying without using up the current destination-region
2168 HeapWord* const end_addr = sd.region_align_down(closure.source());
2169 if (sd.region_align_down(old_src_addr) != end_addr) {
2170 assert(sd.region_align_up(old_src_addr) == end_addr, "only one region");
2171 // The partial object was copied from more than one source region.
2172 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2173
2174 // Move to the next source region, possibly switching spaces as well. All
2175 // args except end_addr may be modified.
2176 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2177 }
2178 }
2179
2180 // Handle the rest obj-by-obj, where we know obj-start.
2181 do {
2182 HeapWord* cur_addr = closure.source();
2183 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2184 src_space_top);
2185 // To handle the case where the final obj in source region extends to next region.
2186 HeapWord* final_obj_start = (end_addr == src_space_top)
2187 ? nullptr
2188 : sd.addr_to_region_ptr(end_addr)->partial_obj_addr();
2189 // Apply closure on objs inside [cur_addr, end_addr)
2190 do {
2191 cur_addr = bitmap->find_obj_beg(cur_addr, end_addr);
2192 if (cur_addr == end_addr) {
2193 break;
2194 }
2195 size_t obj_size;
2196 if (final_obj_start == cur_addr) {
2197 obj_size = pointer_delta(partial_obj_end(end_addr), cur_addr);
2198 } else {
2199 // This obj doesn't extend into next region; size() is safe to use.
2200 obj_size = cast_to_oop(cur_addr)->size();
2201 }
2202 closure.do_addr(cur_addr, obj_size);
2203 cur_addr += obj_size;
2204 } while (cur_addr < end_addr && !closure.is_full());
2205
2206 if (closure.is_full()) {
2207 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2208 closure.complete_region(dest_addr, region_ptr);
2209 return;
2210 }
2211
2212 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2213
2214 // Move to the next source region, possibly switching spaces as well. All
2215 // args except end_addr may be modified.
2216 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2217 } while (true);
2218 }
2219
2220 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
2221 {
2222 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2223 fill_region(cm, cl, region_idx);
2224 }
2225
2226 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
2227 {
2228 // Get a shadow region first
2229 ParallelCompactData& sd = summary_data();
2230 RegionData* const region_ptr = sd.region(region_idx);
2231 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
2232 // The InvalidShadow return value indicates the corresponding heap region is available,
2233 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
2234 // MoveAndUpdateShadowClosure to fill the acquired shadow region.
2235 if (shadow_region == ParCompactionManager::InvalidShadow) {
2236 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2237 region_ptr->shadow_to_normal();
2238 return fill_region(cm, cl, region_idx);
2239 } else {
2240 MoveAndUpdateShadowClosure cl(mark_bitmap(), region_idx, shadow_region);
2241 return fill_region(cm, cl, region_idx);
2242 }
2243 }
2244
2245 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
2246 {
2247 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
2248 }
2249
2250 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx)
2251 {
2252 size_t next = cm->next_shadow_region();
2253 ParallelCompactData& sd = summary_data();
2254 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
2255 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2256
2257 while (next < old_new_top) {
2258 if (sd.region(next)->mark_shadow()) {
2259 region_idx = next;
2260 return true;
2261 }
2262 next = cm->move_next_shadow_region_by(active_gc_threads);
2263 }
2264
2265 return false;
2266 }
2267
2268 // The shadow region is an optimization to address region dependencies in full GC. The basic
2269 // idea is making more regions available by temporally storing their live objects in empty
2270 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
2271 // GC threads need not wait destination regions to be available before processing sources.
2272 //
2273 // A typical workflow would be:
2274 // After draining its own stack and failing to steal from others, a GC worker would pick an
2275 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
2276 // the shadow region by copying live objects from source regions of the unavailable one. Once
2277 // the unavailable region becomes available, the data in the shadow region will be copied back.
2278 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
2279 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
2280 {
2281 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2282
2283 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2284 SpaceInfo* const space_info = _space_info + id;
2285 MutableSpace* const space = space_info->space();
2286
2287 const size_t beg_region =
2288 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
2289 const size_t end_region =
2290 sd.addr_to_region_idx(sd.region_align_down(space->end()));
2291
2292 for (size_t cur = beg_region; cur < end_region; ++cur) {
2293 ParCompactionManager::push_shadow_region(cur);
2294 }
2295 }
2296
2297 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
2298 for (uint i = 0; i < parallel_gc_threads; i++) {
2299 ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i);
2300 cm->set_next_shadow_region(beg_region + i);
2301 }
2302 }
2303
2304 void MoveAndUpdateClosure::copy_partial_obj(size_t partial_obj_size)
2305 {
2306 size_t words = MIN2(partial_obj_size, words_remaining());
2307
2308 // This test is necessary; if omitted, the pointer updates to a partial object
2309 // that crosses the dense prefix boundary could be overwritten.
2310 if (source() != copy_destination()) {
2311 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2312 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2313 }
2314 update_state(words);
2315 }
2316
2317 void MoveAndUpdateClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2318 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
2319 region_ptr->set_completed();
2320 }
2321
2322 void MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
2323 assert(destination() != nullptr, "sanity");
2324 _source = addr;
2325
2326 // The start_array must be updated even if the object is not moving.
2327 if (_start_array != nullptr) {
2328 _start_array->update_for_block(destination(), destination() + words);
2329 }
2330
2331 // Avoid overflow
2332 words = MIN2(words, words_remaining());
2333 assert(words > 0, "inv");
2334
2335 if (copy_destination() != source()) {
2336 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2337 assert(source() != destination(), "inv");
2338 assert(FullGCForwarding::is_forwarded(cast_to_oop(source())), "inv");
2339 assert(FullGCForwarding::forwardee(cast_to_oop(source())) == cast_to_oop(destination()), "inv");
2340 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2341 cast_to_oop(copy_destination())->init_mark();
2342 }
2343
2344 update_state(words);
2345 }
2346
2347 void MoveAndUpdateShadowClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2348 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
2349 // Record the shadow region index
2350 region_ptr->set_shadow_region(_shadow);
2351 // Mark the shadow region as filled to indicate the data is ready to be
2352 // copied back
2353 region_ptr->mark_filled();
2354 // Try to copy the content of the shadow region back to its corresponding
2355 // heap region if available; the GC thread that decreases the destination
2356 // count to zero will do the copying otherwise (see
2357 // PSParallelCompact::decrement_destination_counts).
2358 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
2359 region_ptr->set_completed();
2360 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
2361 ParCompactionManager::push_shadow_region_mt_safe(_shadow);
2362 }
2363 }