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/parallelCleaning.hpp"
61 #include "gc/shared/preservedMarks.inline.hpp"
62 #include "gc/shared/referencePolicy.hpp"
63 #include "gc/shared/referenceProcessor.hpp"
64 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
65 #include "gc/shared/spaceDecorator.hpp"
66 #include "gc/shared/taskTerminator.hpp"
67 #include "gc/shared/weakProcessor.inline.hpp"
68 #include "gc/shared/workerPolicy.hpp"
69 #include "gc/shared/workerThread.hpp"
70 #include "gc/shared/workerUtils.hpp"
71 #include "logging/log.hpp"
72 #include "memory/iterator.inline.hpp"
73 #include "memory/memoryReserver.hpp"
74 #include "memory/metaspaceUtils.hpp"
75 #include "memory/resourceArea.hpp"
76 #include "memory/universe.hpp"
77 #include "nmt/memTracker.hpp"
78 #include "oops/access.inline.hpp"
79 #include "oops/instanceClassLoaderKlass.inline.hpp"
80 #include "oops/instanceKlass.inline.hpp"
81 #include "oops/instanceMirrorKlass.inline.hpp"
82 #include "oops/methodData.hpp"
83 #include "oops/objArrayKlass.inline.hpp"
84 #include "oops/oop.inline.hpp"
85 #include "runtime/atomicAccess.hpp"
86 #include "runtime/handles.inline.hpp"
87 #include "runtime/java.hpp"
88 #include "runtime/safepoint.hpp"
89 #include "runtime/threads.hpp"
90 #include "runtime/vmThread.hpp"
91 #include "services/memoryService.hpp"
92 #include "utilities/align.hpp"
93 #include "utilities/debug.hpp"
94 #include "utilities/events.hpp"
95 #include "utilities/formatBuffer.hpp"
96 #include "utilities/macros.hpp"
97 #include "utilities/stack.inline.hpp"
98 #if INCLUDE_JVMCI
99 #include "jvmci/jvmci.hpp"
100 #endif
101
102 #include <math.h>
103
104 // All sizes are in HeapWords.
105 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
106 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
107 static_assert(ParallelCompactData::RegionSize >= BitsPerWord, "region-start bit word-aligned");
108 const size_t ParallelCompactData::RegionSizeBytes =
109 RegionSize << LogHeapWordSize;
110 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
111 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
112 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
113
114 const ParallelCompactData::RegionData::region_sz_t
115 ParallelCompactData::RegionData::dc_shift = 27;
116
117 const ParallelCompactData::RegionData::region_sz_t
118 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
119
120 const ParallelCompactData::RegionData::region_sz_t
121 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
122
123 const ParallelCompactData::RegionData::region_sz_t
124 ParallelCompactData::RegionData::los_mask = ~dc_mask;
125
126 const ParallelCompactData::RegionData::region_sz_t
127 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
128
129 const ParallelCompactData::RegionData::region_sz_t
130 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
131
132 bool ParallelCompactData::RegionData::is_clear() {
133 return (_destination == nullptr) &&
134 (_source_region == 0) &&
135 (_partial_obj_addr == nullptr) &&
136 (_partial_obj_size == 0) &&
137 (_dc_and_los == 0) &&
138 (_shadow_state == 0);
139 }
140
141 #ifdef ASSERT
142 void ParallelCompactData::RegionData::verify_clear() {
143 assert(_destination == nullptr, "inv");
144 assert(_source_region == 0, "inv");
145 assert(_partial_obj_addr == nullptr, "inv");
146 assert(_partial_obj_size == 0, "inv");
147 assert(_dc_and_los == 0, "inv");
148 assert(_shadow_state == 0, "inv");
149 }
150 #endif
151
152 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
153
154 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
155 ReferenceProcessor* PSParallelCompact::_ref_processor = nullptr;
156
157 void SplitInfo::record(size_t split_region_idx, HeapWord* split_point, size_t preceding_live_words) {
158 assert(split_region_idx != 0, "precondition");
159
160 // Obj denoted by split_point will be deferred to the next space.
161 assert(split_point != nullptr, "precondition");
162
163 const ParallelCompactData& sd = PSParallelCompact::summary_data();
164
165 PSParallelCompact::RegionData* split_region_ptr = sd.region(split_region_idx);
166 assert(preceding_live_words < split_region_ptr->data_size(), "inv");
167
168 HeapWord* preceding_destination = split_region_ptr->destination();
169 assert(preceding_destination != nullptr, "inv");
170
171 // How many regions does the preceding part occupy
172 uint preceding_destination_count;
173 if (preceding_live_words == 0) {
174 preceding_destination_count = 0;
175 } else {
176 // -1 so that the ending address doesn't fall on the region-boundary
177 if (sd.region_align_down(preceding_destination) ==
178 sd.region_align_down(preceding_destination + preceding_live_words - 1)) {
179 preceding_destination_count = 1;
180 } else {
181 preceding_destination_count = 2;
182 }
183 }
184
185 _split_region_idx = split_region_idx;
186 _split_point = split_point;
187 _preceding_live_words = preceding_live_words;
188 _preceding_destination = preceding_destination;
189 _preceding_destination_count = preceding_destination_count;
190 }
191
192 void SplitInfo::clear()
193 {
194 _split_region_idx = 0;
195 _split_point = nullptr;
196 _preceding_live_words = 0;
197 _preceding_destination = nullptr;
198 _preceding_destination_count = 0;
199 assert(!is_valid(), "sanity");
200 }
201
202 #ifdef ASSERT
203 void SplitInfo::verify_clear()
204 {
205 assert(_split_region_idx == 0, "not clear");
206 assert(_split_point == nullptr, "not clear");
207 assert(_preceding_live_words == 0, "not clear");
208 assert(_preceding_destination == nullptr, "not clear");
209 assert(_preceding_destination_count == 0, "not clear");
210 }
211 #endif // #ifdef ASSERT
212
213
214 void PSParallelCompact::print_on(outputStream* st) {
215 _mark_bitmap.print_on(st);
216 }
217
218 ParallelCompactData::ParallelCompactData() :
219 _heap_start(nullptr),
220 DEBUG_ONLY(_heap_end(nullptr) COMMA)
221 _region_vspace(nullptr),
222 _reserved_byte_size(0),
223 _region_data(nullptr),
224 _region_count(0) {}
225
226 bool ParallelCompactData::initialize(MemRegion reserved_heap)
227 {
228 _heap_start = reserved_heap.start();
229 const size_t heap_size = reserved_heap.word_size();
230 DEBUG_ONLY(_heap_end = _heap_start + heap_size;)
231
232 assert(region_align_down(_heap_start) == _heap_start,
233 "region start not aligned");
234
235 return initialize_region_data(heap_size);
236 }
237
238 PSVirtualSpace*
239 ParallelCompactData::create_vspace(size_t count, size_t element_size)
240 {
241 const size_t raw_bytes = count * element_size;
242 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
243 const size_t granularity = os::vm_allocation_granularity();
244 const size_t rs_align = MAX2(page_sz, granularity);
245
246 _reserved_byte_size = align_up(raw_bytes, rs_align);
247
248 ReservedSpace rs = MemoryReserver::reserve(_reserved_byte_size,
249 rs_align,
250 page_sz,
251 mtGC);
252
253 if (!rs.is_reserved()) {
254 // Failed to reserve memory.
255 return nullptr;
256 }
257
258 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, rs.base(),
259 rs.size(), page_sz);
260
261 MemTracker::record_virtual_memory_tag(rs, mtGC);
262
263 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
264
265 if (!vspace->expand_by(_reserved_byte_size)) {
266 // Failed to commit memory.
267
268 delete vspace;
269
270 // Release memory reserved in the space.
271 MemoryReserver::release(rs);
272
273 return nullptr;
274 }
275
276 return vspace;
277 }
278
279 bool ParallelCompactData::initialize_region_data(size_t heap_size)
280 {
281 assert(is_aligned(heap_size, RegionSize), "precondition");
282
283 const size_t count = heap_size >> Log2RegionSize;
284 _region_vspace = create_vspace(count, sizeof(RegionData));
285 if (_region_vspace != nullptr) {
286 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
287 _region_count = count;
288 return true;
289 }
290 return false;
291 }
292
293 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
294 assert(beg_region <= _region_count, "beg_region out of range");
295 assert(end_region <= _region_count, "end_region out of range");
296
297 const size_t region_cnt = end_region - beg_region;
298 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
299 }
300
301 // The total live words on src_region would overflow the target space, so find
302 // the overflowing object and record the split point. The invariant is that an
303 // obj should not cross space boundary.
304 HeapWord* ParallelCompactData::summarize_split_space(size_t src_region,
305 SplitInfo& split_info,
306 HeapWord* const destination,
307 HeapWord* const target_end,
308 HeapWord** target_next) {
309 assert(destination <= target_end, "sanity");
310 assert(destination + _region_data[src_region].data_size() > target_end,
311 "region should not fit into target space");
312 assert(is_region_aligned(target_end), "sanity");
313
314 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
315
316 if (destination + partial_obj_size > target_end) {
317 assert(partial_obj_size > 0, "inv");
318 // The overflowing obj is from a previous region.
319 //
320 // source-regions:
321 //
322 // ***************
323 // | A|AA |
324 // ***************
325 // ^
326 // | split-point
327 //
328 // dest-region:
329 //
330 // ********
331 // |~~~~A |
332 // ********
333 // ^^
334 // || target-space-end
335 // |
336 // | destination
337 //
338 // AAA would overflow target-space.
339 //
340 HeapWord* overflowing_obj = _region_data[src_region].partial_obj_addr();
341 size_t split_region = addr_to_region_idx(overflowing_obj);
342
343 // The number of live words before the overflowing object on this split region
344 size_t preceding_live_words;
345 if (is_region_aligned(overflowing_obj)) {
346 preceding_live_words = 0;
347 } else {
348 // Words accounted by the overflowing object on the split region
349 size_t overflowing_size = pointer_delta(region_align_up(overflowing_obj), overflowing_obj);
350 preceding_live_words = region(split_region)->data_size() - overflowing_size;
351 }
352
353 split_info.record(split_region, overflowing_obj, preceding_live_words);
354
355 // The [overflowing_obj, src_region_start) part has been accounted for, so
356 // must move back the new_top, now that this overflowing obj is deferred.
357 HeapWord* new_top = destination - pointer_delta(region_to_addr(src_region), overflowing_obj);
358
359 // If the overflowing obj was relocated to its original destination,
360 // those destination regions would have their source_region set. Now that
361 // this overflowing obj is relocated somewhere else, reset the
362 // source_region.
363 {
364 size_t range_start = addr_to_region_idx(region_align_up(new_top));
365 size_t range_end = addr_to_region_idx(region_align_up(destination));
366 for (size_t i = range_start; i < range_end; ++i) {
367 region(i)->set_source_region(0);
368 }
369 }
370
371 // Update new top of target space
372 *target_next = new_top;
373
374 return overflowing_obj;
375 }
376
377 // Obj-iteration to locate the overflowing obj
378 HeapWord* region_start = region_to_addr(src_region);
379 HeapWord* region_end = region_start + RegionSize;
380 HeapWord* cur_addr = region_start + partial_obj_size;
381 size_t live_words = partial_obj_size;
382
383 while (true) {
384 assert(cur_addr < region_end, "inv");
385 cur_addr = PSParallelCompact::mark_bitmap()->find_obj_beg(cur_addr, region_end);
386 // There must be an overflowing obj in this region
387 assert(cur_addr < region_end, "inv");
388
389 oop obj = cast_to_oop(cur_addr);
390 size_t obj_size = obj->size();
391 if (destination + live_words + obj_size > target_end) {
392 // Found the overflowing obj
393 split_info.record(src_region, cur_addr, live_words);
394 *target_next = destination + live_words;
395 return cur_addr;
396 }
397
398 live_words += obj_size;
399 cur_addr += obj_size;
400 }
401 }
402
403 size_t ParallelCompactData::live_words_in_space(const MutableSpace* space,
404 HeapWord** full_region_prefix_end) {
405 size_t cur_region = addr_to_region_idx(space->bottom());
406 const size_t end_region = addr_to_region_idx(region_align_up(space->top()));
407 size_t live_words = 0;
408 if (full_region_prefix_end == nullptr) {
409 for (/* empty */; cur_region < end_region; ++cur_region) {
410 live_words += _region_data[cur_region].data_size();
411 }
412 } else {
413 bool first_set = false;
414 for (/* empty */; cur_region < end_region; ++cur_region) {
415 size_t live_words_in_region = _region_data[cur_region].data_size();
416 if (!first_set && live_words_in_region < RegionSize) {
417 *full_region_prefix_end = region_to_addr(cur_region);
418 first_set = true;
419 }
420 live_words += live_words_in_region;
421 }
422 if (!first_set) {
423 // All regions are full of live objs.
424 assert(is_region_aligned(space->top()), "inv");
425 *full_region_prefix_end = space->top();
426 }
427 assert(*full_region_prefix_end != nullptr, "postcondition");
428 assert(is_region_aligned(*full_region_prefix_end), "inv");
429 assert(*full_region_prefix_end >= space->bottom(), "in-range");
430 assert(*full_region_prefix_end <= space->top(), "in-range");
431 }
432 return live_words;
433 }
434
435 bool ParallelCompactData::summarize(SplitInfo& split_info,
436 HeapWord* source_beg, HeapWord* source_end,
437 HeapWord** source_next,
438 HeapWord* target_beg, HeapWord* target_end,
439 HeapWord** target_next)
440 {
441 HeapWord* const source_next_val = source_next == nullptr ? nullptr : *source_next;
442 log_develop_trace(gc, compaction)(
443 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
444 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
445 p2i(source_beg), p2i(source_end), p2i(source_next_val),
446 p2i(target_beg), p2i(target_end), p2i(*target_next));
447
448 size_t cur_region = addr_to_region_idx(source_beg);
449 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
450
451 HeapWord *dest_addr = target_beg;
452 for (/* empty */; cur_region < end_region; cur_region++) {
453 size_t words = _region_data[cur_region].data_size();
454
455 // Skip empty ones
456 if (words == 0) {
457 continue;
458 }
459
460 if (split_info.is_split(cur_region)) {
461 assert(words > split_info.preceding_live_words(), "inv");
462 words -= split_info.preceding_live_words();
463 }
464
465 _region_data[cur_region].set_destination(dest_addr);
466
467 // If cur_region does not fit entirely into the target space, find a point
468 // at which the source space can be 'split' so that part is copied to the
469 // target space and the rest is copied elsewhere.
470 if (dest_addr + words > target_end) {
471 assert(source_next != nullptr, "source_next is null when splitting");
472 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
473 target_end, target_next);
474 return false;
475 }
476
477 uint destination_count = split_info.is_split(cur_region)
478 ? split_info.preceding_destination_count()
479 : 0;
480
481 HeapWord* const last_addr = dest_addr + words - 1;
482 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
483 const size_t dest_region_2 = addr_to_region_idx(last_addr);
484
485 // Initially assume that the destination regions will be the same and
486 // adjust the value below if necessary. Under this assumption, if
487 // cur_region == dest_region_2, then cur_region will be compacted
488 // completely into itself.
489 destination_count += cur_region == dest_region_2 ? 0 : 1;
490 if (dest_region_1 != dest_region_2) {
491 // Destination regions differ; adjust destination_count.
492 destination_count += 1;
493 // Data from cur_region will be copied to the start of dest_region_2.
494 _region_data[dest_region_2].set_source_region(cur_region);
495 } else if (is_region_aligned(dest_addr)) {
496 // Data from cur_region will be copied to the start of the destination
497 // region.
498 _region_data[dest_region_1].set_source_region(cur_region);
499 }
500
501 _region_data[cur_region].set_destination_count(destination_count);
502 dest_addr += words;
503 }
504
505 *target_next = dest_addr;
506 return true;
507 }
508
509 #ifdef ASSERT
510 void ParallelCompactData::verify_clear() {
511 for (uint cur_idx = 0; cur_idx < region_count(); ++cur_idx) {
512 if (!region(cur_idx)->is_clear()) {
513 log_warning(gc)("Uncleared Region: %u", cur_idx);
514 region(cur_idx)->verify_clear();
515 }
516 }
517 }
518 #endif // #ifdef ASSERT
519
520 STWGCTimer PSParallelCompact::_gc_timer;
521 ParallelOldTracer PSParallelCompact::_gc_tracer;
522 elapsedTimer PSParallelCompact::_accumulated_time;
523 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
524 CollectorCounters* PSParallelCompact::_counters = nullptr;
525 ParMarkBitMap PSParallelCompact::_mark_bitmap;
526 ParallelCompactData PSParallelCompact::_summary_data;
527
528 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
529
530 class PCAdjustPointerClosure: public BasicOopIterateClosure {
531 template <typename T>
532 void do_oop_work(T* p) { PSParallelCompact::adjust_pointer(p); }
533
534 public:
535 virtual void do_oop(oop* p) { do_oop_work(p); }
536 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
537
538 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
539 };
540
541 static PCAdjustPointerClosure pc_adjust_pointer_closure;
542
543 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
544
545 void PSParallelCompact::post_initialize() {
546 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
547 _span_based_discoverer.set_span(heap->reserved_region());
548 _ref_processor =
549 new ReferenceProcessor(&_span_based_discoverer,
550 ParallelGCThreads, // mt processing degree
551 ParallelGCThreads, // mt discovery degree
552 false, // concurrent_discovery
553 &_is_alive_closure); // non-header is alive closure
554
555 _counters = new CollectorCounters("Parallel full collection pauses", 1);
556
557 // Initialize static fields in ParCompactionManager.
558 ParCompactionManager::initialize(mark_bitmap());
559 }
560
561 bool PSParallelCompact::initialize_aux_data() {
562 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
563 MemRegion mr = heap->reserved_region();
564 assert(mr.byte_size() != 0, "heap should be reserved");
565
566 initialize_space_info();
567
568 if (!_mark_bitmap.initialize(mr)) {
569 vm_shutdown_during_initialization(
570 err_msg("Unable to allocate %zuKB bitmaps for parallel "
571 "garbage collection for the requested %zuKB heap.",
572 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
573 return false;
574 }
575
576 if (!_summary_data.initialize(mr)) {
577 vm_shutdown_during_initialization(
578 err_msg("Unable to allocate %zuKB card tables for parallel "
579 "garbage collection for the requested %zuKB heap.",
580 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
581 return false;
582 }
583
584 return true;
585 }
586
587 void PSParallelCompact::initialize_space_info()
588 {
589 memset(&_space_info, 0, sizeof(_space_info));
590
591 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
592 PSYoungGen* young_gen = heap->young_gen();
593
594 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
595 _space_info[eden_space_id].set_space(young_gen->eden_space());
596 _space_info[from_space_id].set_space(young_gen->from_space());
597 _space_info[to_space_id].set_space(young_gen->to_space());
598
599 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
600 }
601
602 void
603 PSParallelCompact::clear_data_covering_space(SpaceId id)
604 {
605 // At this point, top is the value before GC, new_top() is the value that will
606 // be set at the end of GC. The marking bitmap is cleared to top; nothing
607 // should be marked above top. The summary data is cleared to the larger of
608 // top & new_top.
609 MutableSpace* const space = _space_info[id].space();
610 HeapWord* const bot = space->bottom();
611 HeapWord* const top = space->top();
612 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
613
614 _mark_bitmap.clear_range(bot, top);
615
616 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
617 const size_t end_region =
618 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
619 _summary_data.clear_range(beg_region, end_region);
620
621 // Clear the data used to 'split' regions.
622 SplitInfo& split_info = _space_info[id].split_info();
623 if (split_info.is_valid()) {
624 split_info.clear();
625 }
626 DEBUG_ONLY(split_info.verify_clear();)
627 }
628
629 void PSParallelCompact::pre_compact()
630 {
631 // Update the from & to space pointers in space_info, since they are swapped
632 // at each young gen gc. Do the update unconditionally (even though a
633 // promotion failure does not swap spaces) because an unknown number of young
634 // collections will have swapped the spaces an unknown number of times.
635 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
636 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
637 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
638 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
639
640 heap->increment_total_collections(true);
641
642 CodeCache::on_gc_marking_cycle_start();
643
644 heap->print_before_gc();
645 heap->trace_heap_before_gc(&_gc_tracer);
646
647 // Fill in TLABs
648 heap->ensure_parsability(true); // retire TLABs
649
650 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
651 Universe::verify("Before GC");
652 }
653
654 DEBUG_ONLY(mark_bitmap()->verify_clear();)
655 DEBUG_ONLY(summary_data().verify_clear();)
656 }
657
658 void PSParallelCompact::post_compact()
659 {
660 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
661 ParCompactionManager::remove_all_shadow_regions();
662
663 CodeCache::on_gc_marking_cycle_finish();
664 CodeCache::arm_all_nmethods();
665
666 // Need to clear claim bits for the next full-gc (marking and adjust-pointers).
667 ClassLoaderDataGraph::clear_claimed_marks();
668
669 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
670 // Clear the marking bitmap, summary data and split info.
671 clear_data_covering_space(SpaceId(id));
672 {
673 MutableSpace* space = _space_info[id].space();
674 HeapWord* top = space->top();
675 HeapWord* new_top = _space_info[id].new_top();
676 if (ZapUnusedHeapArea && new_top < top) {
677 space->mangle_region(MemRegion(new_top, top));
678 }
679 // Update top(). Must be done after clearing the bitmap and summary data.
680 space->set_top(new_top);
681 }
682 }
683
684 #ifdef ASSERT
685 {
686 mark_bitmap()->verify_clear();
687 summary_data().verify_clear();
688 }
689 #endif
690
691 ParCompactionManager::flush_all_string_dedup_requests();
692
693 MutableSpace* const eden_space = _space_info[eden_space_id].space();
694 MutableSpace* const from_space = _space_info[from_space_id].space();
695 MutableSpace* const to_space = _space_info[to_space_id].space();
696
697 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
698 bool eden_empty = eden_space->is_empty();
699
700 // Update heap occupancy information which is used as input to the soft ref
701 // clearing policy at the next gc.
702 Universe::heap()->update_capacity_and_used_at_gc();
703
704 bool young_gen_empty = eden_empty && from_space->is_empty() &&
705 to_space->is_empty();
706
707 PSCardTable* ct = heap->card_table();
708 MemRegion old_mr = heap->old_gen()->committed();
709 if (young_gen_empty) {
710 ct->clear_MemRegion(old_mr);
711 } else {
712 ct->dirty_MemRegion(old_mr);
713 }
714
715 heap->prune_scavengable_nmethods();
716
717 #if COMPILER2_OR_JVMCI
718 DerivedPointerTable::update_pointers();
719 #endif
720
721 // Signal that we have completed a visit to all live objects.
722 Universe::heap()->record_whole_heap_examined_timestamp();
723 }
724
725 HeapWord* PSParallelCompact::compute_dense_prefix_for_old_space(MutableSpace* old_space,
726 HeapWord* full_region_prefix_end) {
727 const size_t region_size = ParallelCompactData::RegionSize;
728 const ParallelCompactData& sd = summary_data();
729
730 // Iteration starts with the region *after* the full-region-prefix-end.
731 const RegionData* const start_region = sd.addr_to_region_ptr(full_region_prefix_end);
732 // If final region is not full, iteration stops before that region,
733 // because fill_dense_prefix_end assumes that prefix_end <= top.
734 const RegionData* const end_region = sd.addr_to_region_ptr(old_space->top());
735 assert(start_region <= end_region, "inv");
736
737 size_t max_waste = old_space->capacity_in_words() * (MarkSweepDeadRatio / 100.0);
738 const RegionData* cur_region = start_region;
739 for (/* empty */; cur_region < end_region; ++cur_region) {
740 assert(region_size >= cur_region->data_size(), "inv");
741 size_t dead_size = region_size - cur_region->data_size();
742 if (max_waste < dead_size) {
743 break;
744 }
745 max_waste -= dead_size;
746 }
747
748 HeapWord* const prefix_end = sd.region_to_addr(cur_region);
749 assert(sd.is_region_aligned(prefix_end), "postcondition");
750 assert(prefix_end >= full_region_prefix_end, "in-range");
751 assert(prefix_end <= old_space->top(), "in-range");
752 return prefix_end;
753 }
754
755 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) {
756 // Comparing two sizes to decide if filling is required:
757 //
758 // The size of the filler (min-obj-size) is 2 heap words with the default
759 // MinObjAlignment, since both markword and klass take 1 heap word.
760 // With +UseCompactObjectHeaders, the minimum filler size is only one word,
761 // because the Klass* gets encoded in the mark-word.
762 //
763 // The size of the gap (if any) right before dense-prefix-end is
764 // MinObjAlignment.
765 //
766 // Need to fill in the gap only if it's smaller than min-obj-size, and the
767 // filler obj will extend to next region.
768
769 if (MinObjAlignment >= checked_cast<int>(CollectedHeap::min_fill_size())) {
770 return;
771 }
772
773 assert(!UseCompactObjectHeaders, "Compact headers can allocate small objects");
774 assert(CollectedHeap::min_fill_size() == 2, "inv");
775 HeapWord* const dense_prefix_end = dense_prefix(id);
776 assert(_summary_data.is_region_aligned(dense_prefix_end), "precondition");
777 assert(dense_prefix_end <= space(id)->top(), "precondition");
778 if (dense_prefix_end == space(id)->top()) {
779 // Must not have single-word gap right before prefix-end/top.
780 return;
781 }
782 RegionData* const region_after_dense_prefix = _summary_data.addr_to_region_ptr(dense_prefix_end);
783
784 if (region_after_dense_prefix->partial_obj_size() != 0 ||
785 _mark_bitmap.is_marked(dense_prefix_end)) {
786 // The region after the dense prefix starts with live bytes.
787 return;
788 }
789
790 HeapWord* block_start = start_array(id)->block_start_reaching_into_card(dense_prefix_end);
791 if (block_start == dense_prefix_end - 1) {
792 assert(!_mark_bitmap.is_marked(block_start), "inv");
793 // There is exactly one heap word gap right before the dense prefix end, so we need a filler object.
794 // The filler object will extend into region_after_dense_prefix.
795 const size_t obj_len = 2; // min-fill-size
796 HeapWord* const obj_beg = dense_prefix_end - 1;
797 CollectedHeap::fill_with_object(obj_beg, obj_len);
798 _mark_bitmap.mark_obj(obj_beg);
799 _summary_data.addr_to_region_ptr(obj_beg)->add_live_obj(1);
800 region_after_dense_prefix->set_partial_obj_size(1);
801 region_after_dense_prefix->set_partial_obj_addr(obj_beg);
802 assert(start_array(id) != nullptr, "sanity");
803 start_array(id)->update_for_block(obj_beg, obj_beg + obj_len);
804 }
805 }
806
807 bool PSParallelCompact::check_maximum_compaction(bool should_do_max_compaction,
808 size_t total_live_words,
809 MutableSpace* const old_space,
810 HeapWord* full_region_prefix_end) {
811
812 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
813
814 // Check System.GC
815 bool is_max_on_system_gc = UseMaximumCompactionOnSystemGC
816 && GCCause::is_user_requested_gc(heap->gc_cause());
817
818 // Check if all live objs are too much for old-gen.
819 const bool is_old_gen_too_full = (total_live_words >= old_space->capacity_in_words());
820
821 // If all regions in old-gen are full
822 const bool is_region_full =
823 full_region_prefix_end >= _summary_data.region_align_down(old_space->top());
824
825 return should_do_max_compaction
826 || is_max_on_system_gc
827 || is_old_gen_too_full
828 || is_region_full;
829 }
830
831 void PSParallelCompact::summary_phase(bool should_do_max_compaction)
832 {
833 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
834
835 MutableSpace* const old_space = _space_info[old_space_id].space();
836 {
837 size_t total_live_words = 0;
838 HeapWord* full_region_prefix_end = nullptr;
839 {
840 // old-gen
841 size_t live_words = _summary_data.live_words_in_space(old_space,
842 &full_region_prefix_end);
843 total_live_words += live_words;
844 }
845 // young-gen
846 for (uint i = eden_space_id; i < last_space_id; ++i) {
847 const MutableSpace* space = _space_info[i].space();
848 size_t live_words = _summary_data.live_words_in_space(space);
849 total_live_words += live_words;
850 _space_info[i].set_new_top(space->bottom() + live_words);
851 _space_info[i].set_dense_prefix(space->bottom());
852 }
853
854 should_do_max_compaction = check_maximum_compaction(should_do_max_compaction,
855 total_live_words,
856 old_space,
857 full_region_prefix_end);
858 {
859 GCTraceTime(Info, gc, phases) tm("Summary Phase: expand", &_gc_timer);
860 // Try to expand old-gen in order to fit all live objs and waste.
861 size_t target_capacity_bytes = total_live_words * HeapWordSize
862 + old_space->capacity_in_bytes() * (MarkSweepDeadRatio / 100);
863 ParallelScavengeHeap::heap()->old_gen()->try_expand_till_size(target_capacity_bytes);
864 }
865
866 HeapWord* dense_prefix_end = should_do_max_compaction
867 ? full_region_prefix_end
868 : compute_dense_prefix_for_old_space(old_space,
869 full_region_prefix_end);
870 SpaceId id = old_space_id;
871 _space_info[id].set_dense_prefix(dense_prefix_end);
872
873 if (dense_prefix_end != old_space->bottom()) {
874 fill_dense_prefix_end(id);
875 }
876
877 // Compacting objs in [dense_prefix_end, old_space->top())
878 _summary_data.summarize(_space_info[id].split_info(),
879 dense_prefix_end, old_space->top(), nullptr,
880 dense_prefix_end, old_space->end(),
881 _space_info[id].new_top_addr());
882 }
883
884 // Summarize the remaining spaces in the young gen. The initial target space
885 // is the old gen. If a space does not fit entirely into the target, then the
886 // remainder is compacted into the space itself and that space becomes the new
887 // target.
888 SpaceId dst_space_id = old_space_id;
889 HeapWord* dst_space_end = old_space->end();
890 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
891 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
892 const MutableSpace* space = _space_info[id].space();
893 const size_t live = pointer_delta(_space_info[id].new_top(),
894 space->bottom());
895 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
896
897 if (live > 0 && live <= available) {
898 // All the live data will fit.
899 bool done = _summary_data.summarize(_space_info[id].split_info(),
900 space->bottom(), space->top(),
901 nullptr,
902 *new_top_addr, dst_space_end,
903 new_top_addr);
904 assert(done, "space must fit into old gen");
905
906 // Reset the new_top value for the space.
907 _space_info[id].set_new_top(space->bottom());
908 } else if (live > 0) {
909 // Attempt to fit part of the source space into the target space.
910 HeapWord* next_src_addr = nullptr;
911 bool done = _summary_data.summarize(_space_info[id].split_info(),
912 space->bottom(), space->top(),
913 &next_src_addr,
914 *new_top_addr, dst_space_end,
915 new_top_addr);
916 assert(!done, "space should not fit into old gen");
917 assert(next_src_addr != nullptr, "sanity");
918
919 // The source space becomes the new target, so the remainder is compacted
920 // within the space itself.
921 dst_space_id = SpaceId(id);
922 dst_space_end = space->end();
923 new_top_addr = _space_info[id].new_top_addr();
924 done = _summary_data.summarize(_space_info[id].split_info(),
925 next_src_addr, space->top(),
926 nullptr,
927 space->bottom(), dst_space_end,
928 new_top_addr);
929 assert(done, "space must fit when compacted into itself");
930 assert(*new_top_addr <= space->top(), "usage should not grow");
931 }
932 }
933 }
934
935 bool PSParallelCompact::invoke(bool clear_all_soft_refs, bool should_do_max_compaction) {
936 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
937 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
938 "should be in vm thread");
939 assert(ref_processor() != nullptr, "Sanity");
940
941 SvcGCMarker sgcm(SvcGCMarker::FULL);
942 IsSTWGCActiveMark mark;
943
944 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
945
946 GCIdMark gc_id_mark;
947 _gc_timer.register_gc_start();
948 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
949
950 GCCause::Cause gc_cause = heap->gc_cause();
951 PSOldGen* old_gen = heap->old_gen();
952 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
953
954 // Make sure data structures are sane, make the heap parsable, and do other
955 // miscellaneous bookkeeping.
956 pre_compact();
957
958 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
959
960 {
961 const uint active_workers =
962 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(),
963 ParallelScavengeHeap::heap()->workers().active_workers(),
964 Threads::number_of_non_daemon_threads());
965 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers);
966
967 GCTraceCPUTime tcpu(&_gc_tracer);
968 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause, true);
969
970 heap->pre_full_gc_dump(&_gc_timer);
971
972 TraceCollectorStats tcs(counters());
973 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause, "end of major GC");
974
975 if (log_is_enabled(Debug, gc, heap, exit)) {
976 accumulated_time()->start();
977 }
978
979 // Let the size policy know we're starting
980 size_policy->major_collection_begin();
981
982 #if COMPILER2_OR_JVMCI
983 DerivedPointerTable::clear();
984 #endif
985
986 ref_processor()->start_discovery(clear_all_soft_refs);
987
988 marking_phase(&_gc_tracer);
989
990 summary_phase(should_do_max_compaction);
991
992 #if COMPILER2_OR_JVMCI
993 assert(DerivedPointerTable::is_active(), "Sanity");
994 DerivedPointerTable::set_active(false);
995 #endif
996
997 forward_to_new_addr();
998
999 adjust_pointers();
1000
1001 compact();
1002
1003 ParCompactionManager::_preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
1004
1005 ParCompactionManager::verify_all_region_stack_empty();
1006
1007 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1008 // done before resizing.
1009 post_compact();
1010
1011 size_policy->major_collection_end();
1012
1013 size_policy->sample_old_gen_used_bytes(MAX2(pre_gc_values.old_gen_used(), old_gen->used_in_bytes()));
1014
1015 if (UseAdaptiveSizePolicy) {
1016 heap->resize_after_full_gc();
1017 }
1018
1019 heap->resize_all_tlabs();
1020
1021 // Resize the metaspace capacity after a collection
1022 MetaspaceGC::compute_new_size();
1023
1024 if (log_is_enabled(Debug, gc, heap, exit)) {
1025 accumulated_time()->stop();
1026 }
1027
1028 heap->print_heap_change(pre_gc_values);
1029
1030 // Track memory usage and detect low memory
1031 MemoryService::track_memory_usage();
1032 heap->update_counters();
1033
1034 heap->post_full_gc_dump(&_gc_timer);
1035
1036 size_policy->record_gc_pause_end_instant();
1037 }
1038
1039 heap->gc_epilogue(true);
1040
1041 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1042 Universe::verify("After GC");
1043 }
1044
1045 heap->print_after_gc();
1046 heap->trace_heap_after_gc(&_gc_tracer);
1047
1048 _gc_timer.register_gc_end();
1049
1050 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1051 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1052
1053 return true;
1054 }
1055
1056 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1057 ParCompactionManager* _cm;
1058
1059 public:
1060 PCAddThreadRootsMarkingTaskClosure(ParCompactionManager* cm) : _cm(cm) { }
1061 void do_thread(Thread* thread) {
1062 ResourceMark rm;
1063
1064 MarkingNMethodClosure mark_and_push_in_blobs(&_cm->_mark_and_push_closure);
1065
1066 thread->oops_do(&_cm->_mark_and_push_closure, &mark_and_push_in_blobs);
1067
1068 // Do the real work
1069 _cm->follow_marking_stacks();
1070 }
1071 };
1072
1073 void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
1074 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1075
1076 ParCompactionManager* cm =
1077 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1078
1079 do {
1080 ScannerTask task;
1081 if (ParCompactionManager::steal(worker_id, task)) {
1082 cm->follow_contents(task, true);
1083 }
1084 cm->follow_marking_stacks();
1085 } while (!terminator.offer_termination());
1086 }
1087
1088 class MarkFromRootsTask : public WorkerTask {
1089 NMethodMarkingScope _nmethod_marking_scope;
1090 ThreadsClaimTokenScope _threads_claim_token_scope;
1091 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
1092 TaskTerminator _terminator;
1093 uint _active_workers;
1094
1095 public:
1096 MarkFromRootsTask(uint active_workers) :
1097 WorkerTask("MarkFromRootsTask"),
1098 _nmethod_marking_scope(),
1099 _threads_claim_token_scope(),
1100 _terminator(active_workers, ParCompactionManager::marking_stacks()),
1101 _active_workers(active_workers) {}
1102
1103 virtual void work(uint worker_id) {
1104 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1105 cm->create_marking_stats_cache();
1106 {
1107 CLDToOopClosure cld_closure(&cm->_mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
1108 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
1109
1110 // Do the real work
1111 cm->follow_marking_stacks();
1112 }
1113
1114 {
1115 PCAddThreadRootsMarkingTaskClosure closure(cm);
1116 Threads::possibly_parallel_threads_do(_active_workers > 1 /* is_par */, &closure);
1117 }
1118
1119 // Mark from OopStorages
1120 {
1121 _oop_storage_set_par_state.oops_do(&cm->_mark_and_push_closure);
1122 // Do the real work
1123 cm->follow_marking_stacks();
1124 }
1125
1126 if (_active_workers > 1) {
1127 steal_marking_work(_terminator, worker_id);
1128 }
1129 }
1130 };
1131
1132 class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
1133 TaskTerminator _terminator;
1134
1135 public:
1136 ParallelCompactRefProcProxyTask(uint max_workers)
1137 : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers),
1138 _terminator(_max_workers, ParCompactionManager::marking_stacks()) {}
1139
1140 void work(uint worker_id) override {
1141 assert(worker_id < _max_workers, "sanity");
1142 ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
1143 BarrierEnqueueDiscoveredFieldClosure enqueue;
1144 ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
1145 _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &cm->_mark_and_push_closure, &enqueue, &complete_gc);
1146 }
1147
1148 void prepare_run_task_hook() override {
1149 _terminator.reset_for_reuse(_queue_count);
1150 }
1151 };
1152
1153 static void flush_marking_stats_cache(const uint num_workers) {
1154 for (uint i = 0; i < num_workers; ++i) {
1155 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(i);
1156 cm->flush_and_destroy_marking_stats_cache();
1157 }
1158 }
1159
1160 class PSParallelCleaningTask : public WorkerTask {
1161 bool _unloading_occurred;
1162 CodeCacheUnloadingTask _code_cache_task;
1163 // Prune dead klasses from subklass/sibling/implementor lists.
1164 KlassCleaningTask _klass_cleaning_task;
1165
1166 public:
1167 PSParallelCleaningTask(bool unloading_occurred) :
1168 WorkerTask("PS Parallel Cleaning"),
1169 _unloading_occurred(unloading_occurred),
1170 _code_cache_task(unloading_occurred),
1171 _klass_cleaning_task() {}
1172
1173 void work(uint worker_id) {
1174 #if INCLUDE_JVMCI
1175 if (EnableJVMCI && worker_id == 0) {
1176 // Serial work; only first worker.
1177 // Clean JVMCI metadata handles.
1178 JVMCI::do_unloading(_unloading_occurred);
1179 }
1180 #endif
1181
1182 // Do first pass of code cache cleaning.
1183 _code_cache_task.work(worker_id);
1184
1185 // Clean all klasses that were not unloaded.
1186 // The weak metadata in klass doesn't need to be
1187 // processed if there was no unloading.
1188 if (_unloading_occurred) {
1189 _klass_cleaning_task.work();
1190 }
1191 }
1192 };
1193
1194 void PSParallelCompact::marking_phase(ParallelOldTracer *gc_tracer) {
1195 // Recursively traverse all live objects and mark them
1196 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
1197
1198 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1199
1200 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
1201 {
1202 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
1203
1204 MarkFromRootsTask task(active_gc_threads);
1205 ParallelScavengeHeap::heap()->workers().run_task(&task);
1206 }
1207
1208 // Process reference objects found during marking
1209 {
1210 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
1211
1212 ReferenceProcessorStats stats;
1213 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
1214
1215 ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues());
1216 stats = ref_processor()->process_discovered_references(task, &ParallelScavengeHeap::heap()->workers(), pt);
1217
1218 gc_tracer->report_gc_reference_stats(stats);
1219 pt.print_all_references();
1220 }
1221
1222 {
1223 GCTraceTime(Debug, gc, phases) tm("Flush Marking Stats", &_gc_timer);
1224
1225 flush_marking_stats_cache(active_gc_threads);
1226 }
1227
1228 // This is the point where the entire marking should have completed.
1229 ParCompactionManager::verify_all_marking_stack_empty();
1230
1231 {
1232 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
1233 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(),
1234 is_alive_closure(),
1235 &do_nothing_cl,
1236 1);
1237 }
1238
1239 {
1240 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
1241
1242 ClassUnloadingContext ctx(active_gc_threads /* num_nmethod_unlink_workers */,
1243 false /* unregister_nmethods_during_purge */,
1244 false /* lock_nmethod_free_separately */);
1245
1246 {
1247 CodeCache::UnlinkingScope scope(is_alive_closure());
1248
1249 // Follow system dictionary roots and unload classes.
1250 bool unloading_occurred = SystemDictionary::do_unloading(&_gc_timer);
1251
1252 PSParallelCleaningTask task{unloading_occurred};
1253 ParallelScavengeHeap::heap()->workers().run_task(&task);
1254 }
1255
1256 {
1257 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
1258 // Release unloaded nmethod's memory.
1259 ctx.purge_nmethods();
1260 }
1261 {
1262 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", &_gc_timer);
1263 ParallelScavengeHeap::heap()->prune_unlinked_nmethods();
1264 }
1265 {
1266 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
1267 ctx.free_nmethods();
1268 }
1269 {
1270 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1271 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", gc_timer());
1272 ClassLoaderDataGraph::purge(true /* at_safepoint */);
1273 DEBUG_ONLY(MetaspaceUtils::verify();)
1274 }
1275 }
1276
1277 {
1278 GCTraceTime(Debug, gc, phases) tm("Report Object Count", &_gc_timer);
1279 _gc_tracer.report_object_count_after_gc(is_alive_closure(), &ParallelScavengeHeap::heap()->workers());
1280 }
1281 #if TASKQUEUE_STATS
1282 ParCompactionManager::print_and_reset_taskqueue_stats();
1283 #endif
1284 }
1285
1286 template<typename Func>
1287 void PSParallelCompact::adjust_in_space_helper(SpaceId id, volatile uint* claim_counter, Func&& on_stripe) {
1288 MutableSpace* sp = PSParallelCompact::space(id);
1289 HeapWord* const bottom = sp->bottom();
1290 HeapWord* const top = sp->top();
1291 if (bottom == top) {
1292 return;
1293 }
1294
1295 const uint num_regions_per_stripe = 2;
1296 const size_t region_size = ParallelCompactData::RegionSize;
1297 const size_t stripe_size = num_regions_per_stripe * region_size;
1298
1299 while (true) {
1300 uint counter = AtomicAccess::fetch_then_add(claim_counter, num_regions_per_stripe);
1301 HeapWord* cur_stripe = bottom + counter * region_size;
1302 if (cur_stripe >= top) {
1303 break;
1304 }
1305 HeapWord* stripe_end = MIN2(cur_stripe + stripe_size, top);
1306 on_stripe(cur_stripe, stripe_end);
1307 }
1308 }
1309
1310 void PSParallelCompact::adjust_in_old_space(volatile uint* claim_counter) {
1311 // Regions in old-space shouldn't be split.
1312 assert(!_space_info[old_space_id].split_info().is_valid(), "inv");
1313
1314 auto scan_obj_with_limit = [&] (HeapWord* obj_start, HeapWord* left, HeapWord* right) {
1315 assert(mark_bitmap()->is_marked(obj_start), "inv");
1316 oop obj = cast_to_oop(obj_start);
1317 return obj->oop_iterate_size(&pc_adjust_pointer_closure, MemRegion(left, right));
1318 };
1319
1320 adjust_in_space_helper(old_space_id, claim_counter, [&] (HeapWord* stripe_start, HeapWord* stripe_end) {
1321 assert(_summary_data.is_region_aligned(stripe_start), "inv");
1322 RegionData* cur_region = _summary_data.addr_to_region_ptr(stripe_start);
1323 HeapWord* obj_start;
1324 if (cur_region->partial_obj_size() != 0) {
1325 obj_start = cur_region->partial_obj_addr();
1326 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1327 } else {
1328 obj_start = stripe_start;
1329 }
1330
1331 while (obj_start < stripe_end) {
1332 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1333 if (obj_start >= stripe_end) {
1334 break;
1335 }
1336 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1337 }
1338 });
1339 }
1340
1341 void PSParallelCompact::adjust_in_young_space(SpaceId id, volatile uint* claim_counter) {
1342 adjust_in_space_helper(id, claim_counter, [](HeapWord* stripe_start, HeapWord* stripe_end) {
1343 HeapWord* obj_start = stripe_start;
1344 while (obj_start < stripe_end) {
1345 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1346 if (obj_start >= stripe_end) {
1347 break;
1348 }
1349 oop obj = cast_to_oop(obj_start);
1350 obj_start += obj->oop_iterate_size(&pc_adjust_pointer_closure);
1351 }
1352 });
1353 }
1354
1355 void PSParallelCompact::adjust_pointers_in_spaces(uint worker_id, volatile uint* claim_counters) {
1356 auto start_time = Ticks::now();
1357 adjust_in_old_space(&claim_counters[0]);
1358 for (uint id = eden_space_id; id < last_space_id; ++id) {
1359 adjust_in_young_space(SpaceId(id), &claim_counters[id]);
1360 }
1361 log_trace(gc, phases)("adjust_pointers_in_spaces worker %u: %.3f ms", worker_id, (Ticks::now() - start_time).seconds() * 1000);
1362 }
1363
1364 class PSAdjustTask final : public WorkerTask {
1365 ThreadsClaimTokenScope _threads_claim_token_scope;
1366 WeakProcessor::Task _weak_proc_task;
1367 OopStorageSetStrongParState<false, false> _oop_storage_iter;
1368 uint _nworkers;
1369 volatile bool _code_cache_claimed;
1370 volatile uint _claim_counters[PSParallelCompact::last_space_id] = {};
1371
1372 bool try_claim_code_cache_task() {
1373 return AtomicAccess::load(&_code_cache_claimed) == false
1374 && AtomicAccess::cmpxchg(&_code_cache_claimed, false, true) == false;
1375 }
1376
1377 public:
1378 PSAdjustTask(uint nworkers) :
1379 WorkerTask("PSAdjust task"),
1380 _threads_claim_token_scope(),
1381 _weak_proc_task(nworkers),
1382 _oop_storage_iter(),
1383 _nworkers(nworkers),
1384 _code_cache_claimed(false) {
1385
1386 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
1387 }
1388
1389 void work(uint worker_id) {
1390 {
1391 // Pointers in heap.
1392 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1393 cm->preserved_marks()->adjust_during_full_gc();
1394
1395 PSParallelCompact::adjust_pointers_in_spaces(worker_id, _claim_counters);
1396 }
1397
1398 {
1399 // All (strong and weak) CLDs.
1400 CLDToOopClosure cld_closure(&pc_adjust_pointer_closure, ClassLoaderData::_claim_stw_fullgc_adjust);
1401 ClassLoaderDataGraph::cld_do(&cld_closure);
1402 }
1403
1404 {
1405 // Threads stack frames. No need to visit on-stack nmethods, because all
1406 // nmethods are visited in one go via CodeCache::nmethods_do.
1407 ResourceMark rm;
1408 Threads::possibly_parallel_oops_do(_nworkers > 1, &pc_adjust_pointer_closure, nullptr);
1409 if (try_claim_code_cache_task()) {
1410 NMethodToOopClosure adjust_code(&pc_adjust_pointer_closure, NMethodToOopClosure::FixRelocations);
1411 CodeCache::nmethods_do(&adjust_code);
1412 }
1413 }
1414
1415 {
1416 // VM internal strong and weak roots.
1417 _oop_storage_iter.oops_do(&pc_adjust_pointer_closure);
1418 AlwaysTrueClosure always_alive;
1419 _weak_proc_task.work(worker_id, &always_alive, &pc_adjust_pointer_closure);
1420 }
1421 }
1422 };
1423
1424 void PSParallelCompact::adjust_pointers() {
1425 // Adjust the pointers to reflect the new locations
1426 GCTraceTime(Info, gc, phases) tm("Adjust Pointers", &_gc_timer);
1427 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1428 PSAdjustTask task(nworkers);
1429 ParallelScavengeHeap::heap()->workers().run_task(&task);
1430 }
1431
1432 // Split [start, end) evenly for a number of workers and return the
1433 // range for worker_id.
1434 static void split_regions_for_worker(size_t start, size_t end,
1435 uint worker_id, uint num_workers,
1436 size_t* worker_start, size_t* worker_end) {
1437 assert(start < end, "precondition");
1438 assert(num_workers > 0, "precondition");
1439 assert(worker_id < num_workers, "precondition");
1440
1441 size_t num_regions = end - start;
1442 size_t num_regions_per_worker = num_regions / num_workers;
1443 size_t remainder = num_regions % num_workers;
1444 // The first few workers will get one extra.
1445 *worker_start = start + worker_id * num_regions_per_worker
1446 + MIN2(checked_cast<size_t>(worker_id), remainder);
1447 *worker_end = *worker_start + num_regions_per_worker
1448 + (worker_id < remainder ? 1 : 0);
1449 }
1450
1451 void PSParallelCompact::forward_to_new_addr() {
1452 GCTraceTime(Info, gc, phases) tm("Forward", &_gc_timer);
1453 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1454
1455 struct ForwardTask final : public WorkerTask {
1456 uint _num_workers;
1457
1458 explicit ForwardTask(uint num_workers) :
1459 WorkerTask("PSForward task"),
1460 _num_workers(num_workers) {}
1461
1462 static void forward_objs_in_range(ParCompactionManager* cm,
1463 HeapWord* start,
1464 HeapWord* end,
1465 HeapWord* destination) {
1466 HeapWord* cur_addr = start;
1467 HeapWord* new_addr = destination;
1468
1469 while (cur_addr < end) {
1470 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, end);
1471 if (cur_addr >= end) {
1472 return;
1473 }
1474 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1475 oop obj = cast_to_oop(cur_addr);
1476 if (new_addr != cur_addr) {
1477 cm->preserved_marks()->push_if_necessary(obj, obj->mark());
1478 FullGCForwarding::forward_to(obj, cast_to_oop(new_addr));
1479 }
1480 size_t obj_size = obj->size();
1481 new_addr += obj_size;
1482 cur_addr += obj_size;
1483 }
1484 }
1485
1486 void work(uint worker_id) override {
1487 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1488 for (uint id = old_space_id; id < last_space_id; ++id) {
1489 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1490 HeapWord* dense_prefix_addr = dense_prefix(SpaceId(id));
1491 HeapWord* top = sp->top();
1492
1493 if (dense_prefix_addr == top) {
1494 // Empty space
1495 continue;
1496 }
1497
1498 const SplitInfo& split_info = _space_info[SpaceId(id)].split_info();
1499 size_t dense_prefix_region = _summary_data.addr_to_region_idx(dense_prefix_addr);
1500 size_t top_region = _summary_data.addr_to_region_idx(_summary_data.region_align_up(top));
1501 size_t start_region;
1502 size_t end_region;
1503 split_regions_for_worker(dense_prefix_region, top_region,
1504 worker_id, _num_workers,
1505 &start_region, &end_region);
1506 for (size_t cur_region = start_region; cur_region < end_region; ++cur_region) {
1507 RegionData* region_ptr = _summary_data.region(cur_region);
1508 size_t partial_obj_size = region_ptr->partial_obj_size();
1509
1510 if (partial_obj_size == ParallelCompactData::RegionSize) {
1511 // No obj-start
1512 continue;
1513 }
1514
1515 HeapWord* region_start = _summary_data.region_to_addr(cur_region);
1516 HeapWord* region_end = region_start + ParallelCompactData::RegionSize;
1517
1518 if (split_info.is_split(cur_region)) {
1519 // Part 1: will be relocated to space-1
1520 HeapWord* preceding_destination = split_info.preceding_destination();
1521 HeapWord* split_point = split_info.split_point();
1522 forward_objs_in_range(cm, region_start + partial_obj_size, split_point, preceding_destination + partial_obj_size);
1523
1524 // Part 2: will be relocated to space-2
1525 HeapWord* destination = region_ptr->destination();
1526 forward_objs_in_range(cm, split_point, region_end, destination);
1527 } else {
1528 HeapWord* destination = region_ptr->destination();
1529 forward_objs_in_range(cm, region_start + partial_obj_size, region_end, destination + partial_obj_size);
1530 }
1531 }
1532 }
1533 }
1534 } task(nworkers);
1535
1536 ParallelScavengeHeap::heap()->workers().run_task(&task);
1537 DEBUG_ONLY(verify_forward();)
1538 }
1539
1540 #ifdef ASSERT
1541 void PSParallelCompact::verify_forward() {
1542 HeapWord* const old_dense_prefix_addr = dense_prefix(SpaceId(old_space_id));
1543 // The destination addr for the first live obj after dense-prefix.
1544 HeapWord* bump_ptr = old_dense_prefix_addr
1545 + _summary_data.addr_to_region_ptr(old_dense_prefix_addr)->partial_obj_size();
1546 SpaceId bump_ptr_space = old_space_id;
1547
1548 for (uint id = old_space_id; id < last_space_id; ++id) {
1549 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1550 // Only verify objs after dense-prefix, because those before dense-prefix are not moved (forwarded).
1551 HeapWord* cur_addr = dense_prefix(SpaceId(id));
1552 HeapWord* top = sp->top();
1553
1554 while (cur_addr < top) {
1555 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, top);
1556 if (cur_addr >= top) {
1557 break;
1558 }
1559 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1560 assert(bump_ptr <= _space_info[bump_ptr_space].new_top(), "inv");
1561 // Move to the space containing cur_addr
1562 if (bump_ptr == _space_info[bump_ptr_space].new_top()) {
1563 bump_ptr = space(space_id(cur_addr))->bottom();
1564 bump_ptr_space = space_id(bump_ptr);
1565 }
1566 oop obj = cast_to_oop(cur_addr);
1567 if (cur_addr == bump_ptr) {
1568 assert(!FullGCForwarding::is_forwarded(obj), "inv");
1569 } else {
1570 assert(FullGCForwarding::forwardee(obj) == cast_to_oop(bump_ptr), "inv");
1571 }
1572 bump_ptr += obj->size();
1573 cur_addr += obj->size();
1574 }
1575 }
1576 }
1577 #endif
1578
1579 // Helper class to print 8 region numbers per line and then print the total at the end.
1580 class FillableRegionLogger : public StackObj {
1581 private:
1582 Log(gc, compaction) log;
1583 static const int LineLength = 8;
1584 size_t _regions[LineLength];
1585 int _next_index;
1586 bool _enabled;
1587 size_t _total_regions;
1588 public:
1589 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
1590 ~FillableRegionLogger() {
1591 log.trace("%zu initially fillable regions", _total_regions);
1592 }
1593
1594 void print_line() {
1595 if (!_enabled || _next_index == 0) {
1596 return;
1597 }
1598 FormatBuffer<> line("Fillable: ");
1599 for (int i = 0; i < _next_index; i++) {
1600 line.append(" %7zu", _regions[i]);
1601 }
1602 log.trace("%s", line.buffer());
1603 _next_index = 0;
1604 }
1605
1606 void handle(size_t region) {
1607 if (!_enabled) {
1608 return;
1609 }
1610 _regions[_next_index++] = region;
1611 if (_next_index == LineLength) {
1612 print_line();
1613 }
1614 _total_regions++;
1615 }
1616 };
1617
1618 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
1619 {
1620 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
1621
1622 // Find the threads that are active
1623 uint worker_id = 0;
1624
1625 // Find all regions that are available (can be filled immediately) and
1626 // distribute them to the thread stacks. The iteration is done in reverse
1627 // order (high to low) so the regions will be removed in ascending order.
1628
1629 const ParallelCompactData& sd = PSParallelCompact::summary_data();
1630
1631 // id + 1 is used to test termination so unsigned can
1632 // be used with an old_space_id == 0.
1633 FillableRegionLogger region_logger;
1634 for (unsigned int id = last_space_id - 1; id + 1 > old_space_id; --id) {
1635 SpaceInfo* const space_info = _space_info + id;
1636 HeapWord* const new_top = space_info->new_top();
1637
1638 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
1639 const size_t end_region =
1640 sd.addr_to_region_idx(sd.region_align_up(new_top));
1641
1642 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
1643 if (sd.region(cur)->claim_unsafe()) {
1644 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1645 bool result = sd.region(cur)->mark_normal();
1646 assert(result, "Must succeed at this point.");
1647 cm->region_stack()->push(cur);
1648 region_logger.handle(cur);
1649 // Assign regions to tasks in round-robin fashion.
1650 if (++worker_id == parallel_gc_threads) {
1651 worker_id = 0;
1652 }
1653 }
1654 }
1655 region_logger.print_line();
1656 }
1657 }
1658
1659 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
1660 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1661
1662 ParCompactionManager* cm =
1663 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1664
1665 // Drain the stacks that have been preloaded with regions
1666 // that are ready to fill.
1667
1668 cm->drain_region_stacks();
1669
1670 guarantee(cm->region_stack()->is_empty(), "Not empty");
1671
1672 size_t region_index = 0;
1673
1674 while (true) {
1675 if (ParCompactionManager::steal(worker_id, region_index)) {
1676 PSParallelCompact::fill_and_update_region(cm, region_index);
1677 cm->drain_region_stacks();
1678 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
1679 // Fill and update an unavailable region with the help of a shadow region
1680 PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
1681 cm->drain_region_stacks();
1682 } else {
1683 if (terminator->offer_termination()) {
1684 break;
1685 }
1686 // Go around again.
1687 }
1688 }
1689 }
1690
1691 class FillDensePrefixAndCompactionTask: public WorkerTask {
1692 TaskTerminator _terminator;
1693
1694 public:
1695 FillDensePrefixAndCompactionTask(uint active_workers) :
1696 WorkerTask("FillDensePrefixAndCompactionTask"),
1697 _terminator(active_workers, ParCompactionManager::region_task_queues()) {
1698 }
1699
1700 virtual void work(uint worker_id) {
1701 if (worker_id == 0) {
1702 auto start = Ticks::now();
1703 PSParallelCompact::fill_dead_objs_in_dense_prefix();
1704 log_trace(gc, phases)("Fill dense prefix by worker 0: %.3f ms", (Ticks::now() - start).seconds() * 1000);
1705 }
1706 compaction_with_stealing_work(&_terminator, worker_id);
1707 }
1708 };
1709
1710 void PSParallelCompact::fill_range_in_dense_prefix(HeapWord* start, HeapWord* end) {
1711 #ifdef ASSERT
1712 {
1713 assert(start < end, "precondition");
1714 assert(mark_bitmap()->find_obj_beg(start, end) == end, "precondition");
1715 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1716 if (start != bottom) {
1717 // The preceding live obj.
1718 HeapWord* obj_start = mark_bitmap()->find_obj_beg_reverse(bottom, start);
1719 HeapWord* obj_end = obj_start + cast_to_oop(obj_start)->size();
1720 assert(obj_end == start, "precondition");
1721 }
1722 }
1723 #endif
1724
1725 CollectedHeap::fill_with_objects(start, pointer_delta(end, start));
1726 HeapWord* addr = start;
1727 do {
1728 size_t size = cast_to_oop(addr)->size();
1729 start_array(old_space_id)->update_for_block(addr, addr + size);
1730 addr += size;
1731 } while (addr < end);
1732 }
1733
1734 void PSParallelCompact::fill_dead_objs_in_dense_prefix() {
1735 ParMarkBitMap* bitmap = mark_bitmap();
1736
1737 HeapWord* const bottom = _space_info[old_space_id].space()->bottom();
1738 HeapWord* const prefix_end = dense_prefix(old_space_id);
1739
1740 const size_t region_size = ParallelCompactData::RegionSize;
1741
1742 // Fill dead space in [start_addr, end_addr)
1743 HeapWord* const start_addr = bottom;
1744 HeapWord* const end_addr = prefix_end;
1745
1746 for (HeapWord* cur_addr = start_addr; cur_addr < end_addr; /* empty */) {
1747 RegionData* cur_region_ptr = _summary_data.addr_to_region_ptr(cur_addr);
1748 if (cur_region_ptr->data_size() == region_size) {
1749 // Full; no dead space. Next region.
1750 if (_summary_data.is_region_aligned(cur_addr)) {
1751 cur_addr += region_size;
1752 } else {
1753 cur_addr = _summary_data.region_align_up(cur_addr);
1754 }
1755 continue;
1756 }
1757
1758 // Fill dead space inside cur_region.
1759 if (_summary_data.is_region_aligned(cur_addr)) {
1760 cur_addr += cur_region_ptr->partial_obj_size();
1761 }
1762
1763 HeapWord* region_end_addr = _summary_data.region_align_up(cur_addr + 1);
1764 assert(region_end_addr <= end_addr, "inv");
1765 while (cur_addr < region_end_addr) {
1766 // Use end_addr to allow filler-obj to cross region boundary.
1767 HeapWord* live_start = bitmap->find_obj_beg(cur_addr, end_addr);
1768 if (cur_addr != live_start) {
1769 // Found dead space [cur_addr, live_start).
1770 fill_range_in_dense_prefix(cur_addr, live_start);
1771 }
1772 if (live_start >= region_end_addr) {
1773 cur_addr = live_start;
1774 break;
1775 }
1776 assert(bitmap->is_marked(live_start), "inv");
1777 cur_addr = live_start + cast_to_oop(live_start)->size();
1778 }
1779 }
1780 }
1781
1782 void PSParallelCompact::compact() {
1783 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
1784
1785 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1786
1787 initialize_shadow_regions(active_gc_threads);
1788 prepare_region_draining_tasks(active_gc_threads);
1789
1790 {
1791 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
1792
1793 FillDensePrefixAndCompactionTask task(active_gc_threads);
1794 ParallelScavengeHeap::heap()->workers().run_task(&task);
1795
1796 #ifdef ASSERT
1797 verify_filler_in_dense_prefix();
1798
1799 // Verify that all regions have been processed.
1800 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1801 verify_complete(SpaceId(id));
1802 }
1803 #endif
1804 }
1805 }
1806
1807 #ifdef ASSERT
1808 void PSParallelCompact::verify_filler_in_dense_prefix() {
1809 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1810 HeapWord* dense_prefix_end = dense_prefix(old_space_id);
1811
1812 const size_t region_size = ParallelCompactData::RegionSize;
1813
1814 for (HeapWord* cur_addr = bottom; cur_addr < dense_prefix_end; /* empty */) {
1815 RegionData* cur_region_ptr = _summary_data.addr_to_region_ptr(cur_addr);
1816 if (cur_region_ptr->data_size() == region_size) {
1817 // Full; no dead space. Next region.
1818 if (_summary_data.is_region_aligned(cur_addr)) {
1819 cur_addr += region_size;
1820 } else {
1821 cur_addr = _summary_data.region_align_up(cur_addr);
1822 }
1823 continue;
1824 }
1825
1826 // This region contains filler objs.
1827 if (_summary_data.is_region_aligned(cur_addr)) {
1828 cur_addr += cur_region_ptr->partial_obj_size();
1829 }
1830
1831 HeapWord* region_end_addr = _summary_data.region_align_up(cur_addr + 1);
1832 assert(region_end_addr <= dense_prefix_end, "inv");
1833
1834 while (cur_addr < region_end_addr) {
1835 oop obj = cast_to_oop(cur_addr);
1836 oopDesc::verify(obj);
1837 if (!mark_bitmap()->is_marked(cur_addr)) {
1838 Klass* k = cast_to_oop(cur_addr)->klass();
1839 assert(k == Universe::fillerArrayKlass() || k == vmClasses::FillerObject_klass(), "inv");
1840 }
1841 cur_addr += obj->size();
1842 }
1843 }
1844 }
1845
1846 void PSParallelCompact::verify_complete(SpaceId space_id) {
1847 // All Regions served as compaction targets, from dense_prefix() to
1848 // new_top(), should be marked as filled and all Regions between new_top()
1849 // and top() should be available (i.e., should have been emptied).
1850 ParallelCompactData& sd = summary_data();
1851 SpaceInfo si = _space_info[space_id];
1852 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
1853 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
1854 const size_t beg_region = sd.addr_to_region_idx(si.dense_prefix());
1855 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
1856 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
1857
1858 size_t cur_region;
1859 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
1860 const RegionData* const c = sd.region(cur_region);
1861 assert(c->completed(), "region %zu not filled: destination_count=%u",
1862 cur_region, c->destination_count());
1863 }
1864
1865 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
1866 const RegionData* const c = sd.region(cur_region);
1867 assert(c->available(), "region %zu not empty: destination_count=%u",
1868 cur_region, c->destination_count());
1869 }
1870 }
1871 #endif // #ifdef ASSERT
1872
1873 // Return the SpaceId for the space containing addr. If addr is not in the
1874 // heap, last_space_id is returned. In debug mode it expects the address to be
1875 // in the heap and asserts such.
1876 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
1877 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
1878
1879 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1880 if (_space_info[id].space()->contains(addr)) {
1881 return SpaceId(id);
1882 }
1883 }
1884
1885 assert(false, "no space contains the addr");
1886 return last_space_id;
1887 }
1888
1889 // Skip over count live words starting from beg, and return the address of the
1890 // next live word. Callers must also ensure that there are enough live words in
1891 // the range [beg, end) to skip.
1892 HeapWord* PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
1893 {
1894 ParMarkBitMap* m = mark_bitmap();
1895 HeapWord* cur_addr = beg;
1896 while (true) {
1897 cur_addr = m->find_obj_beg(cur_addr, end);
1898 assert(cur_addr < end, "inv");
1899 size_t obj_size = cast_to_oop(cur_addr)->size();
1900 // Strictly greater-than
1901 if (obj_size > count) {
1902 return cur_addr + count;
1903 }
1904 count -= obj_size;
1905 cur_addr += obj_size;
1906 }
1907 }
1908
1909 // On starting to fill a destination region (dest-region), we need to know the
1910 // location of the word that will be at the start of the dest-region after
1911 // compaction. A dest-region can have one or more source regions, but only the
1912 // first source-region contains this location. This location is retrieved by
1913 // calling `first_src_addr` on a dest-region.
1914 // Conversely, a source-region has a dest-region which holds the destination of
1915 // the first live word on this source-region, based on which the destination
1916 // for the rest of live words can be derived.
1917 //
1918 // Note:
1919 // There is some complication due to space-boundary-fragmentation (an obj can't
1920 // cross space-boundary) -- a source-region may be split and behave like two
1921 // distinct regions with their own dest-region, as depicted below.
1922 //
1923 // source-region: region-n
1924 //
1925 // **********************
1926 // | A|A~~~~B|B |
1927 // **********************
1928 // n-1 n n+1
1929 //
1930 // AA, BB denote two live objs. ~~~~ denotes unknown number of live objs.
1931 //
1932 // Assuming the dest-region for region-n is the final region before
1933 // old-space-end and its first-live-word is the middle of AA, the heap content
1934 // will look like the following after compaction:
1935 //
1936 // ************** *************
1937 // A|A~~~~ | |BB |
1938 // ************** *************
1939 // ^ ^
1940 // | old-space-end | eden-space-start
1941 //
1942 // Therefore, in this example, region-n will have two dest-regions:
1943 // 1. the final region in old-space
1944 // 2. the first region in eden-space.
1945 // To handle this special case, we introduce the concept of split-region, whose
1946 // contents are relocated to two spaces. `SplitInfo` captures all necessary
1947 // info about the split, the first part, spliting-point, and the second part.
1948 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
1949 SpaceId src_space_id,
1950 size_t src_region_idx)
1951 {
1952 const size_t RegionSize = ParallelCompactData::RegionSize;
1953 const ParallelCompactData& sd = summary_data();
1954 assert(sd.is_region_aligned(dest_addr), "precondition");
1955
1956 const RegionData* const src_region_ptr = sd.region(src_region_idx);
1957 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
1958
1959 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
1960 HeapWord* const src_region_destination = src_region_ptr->destination();
1961
1962 HeapWord* const region_start = sd.region_to_addr(src_region_idx);
1963 HeapWord* const region_end = sd.region_to_addr(src_region_idx) + RegionSize;
1964
1965 // Identify the actual destination for the first live words on this region,
1966 // taking split-region into account.
1967 HeapWord* region_start_destination;
1968 const SplitInfo& split_info = _space_info[src_space_id].split_info();
1969 if (split_info.is_split(src_region_idx)) {
1970 // The second part of this split region; use the recorded split point.
1971 if (dest_addr == src_region_destination) {
1972 return split_info.split_point();
1973 }
1974 region_start_destination = split_info.preceding_destination();
1975 } else {
1976 region_start_destination = src_region_destination;
1977 }
1978
1979 // Calculate the offset to be skipped
1980 size_t words_to_skip = pointer_delta(dest_addr, region_start_destination);
1981
1982 HeapWord* result;
1983 if (partial_obj_size > words_to_skip) {
1984 result = region_start + words_to_skip;
1985 } else {
1986 words_to_skip -= partial_obj_size;
1987 result = skip_live_words(region_start + partial_obj_size, region_end, words_to_skip);
1988 }
1989
1990 if (split_info.is_split(src_region_idx)) {
1991 assert(result < split_info.split_point(), "postcondition");
1992 } else {
1993 assert(result < region_end, "postcondition");
1994 }
1995
1996 return result;
1997 }
1998
1999 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2000 SpaceId src_space_id,
2001 size_t beg_region,
2002 HeapWord* end_addr)
2003 {
2004 ParallelCompactData& sd = summary_data();
2005
2006 #ifdef ASSERT
2007 MutableSpace* const src_space = _space_info[src_space_id].space();
2008 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2009 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2010 "src_space_id does not match beg_addr");
2011 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2012 "src_space_id does not match end_addr");
2013 #endif // #ifdef ASSERT
2014
2015 RegionData* const beg = sd.region(beg_region);
2016 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2017
2018 // Regions up to new_top() are enqueued if they become available.
2019 HeapWord* const new_top = _space_info[src_space_id].new_top();
2020 RegionData* const enqueue_end =
2021 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2022
2023 for (RegionData* cur = beg; cur < end; ++cur) {
2024 assert(cur->data_size() > 0, "region must have live data");
2025 cur->decrement_destination_count();
2026 if (cur < enqueue_end && cur->available() && cur->claim()) {
2027 if (cur->mark_normal()) {
2028 cm->push_region(sd.region(cur));
2029 } else if (cur->mark_copied()) {
2030 // Try to copy the content of the shadow region back to its corresponding
2031 // heap region if the shadow region is filled. Otherwise, the GC thread
2032 // fills the shadow region will copy the data back (see
2033 // MoveAndUpdateShadowClosure::complete_region).
2034 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2035 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2036 cur->set_completed();
2037 }
2038 }
2039 }
2040 }
2041
2042 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2043 SpaceId& src_space_id,
2044 HeapWord*& src_space_top,
2045 HeapWord* end_addr)
2046 {
2047 ParallelCompactData& sd = PSParallelCompact::summary_data();
2048
2049 size_t src_region_idx = 0;
2050
2051 // Skip empty regions (if any) up to the top of the space.
2052 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2053 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2054 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2055 const RegionData* const top_region_ptr = sd.addr_to_region_ptr(top_aligned_up);
2056
2057 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2058 ++src_region_ptr;
2059 }
2060
2061 if (src_region_ptr < top_region_ptr) {
2062 // Found the first non-empty region in the same space.
2063 src_region_idx = sd.region(src_region_ptr);
2064 closure.set_source(sd.region_to_addr(src_region_idx));
2065 return src_region_idx;
2066 }
2067
2068 // Switch to a new source space and find the first non-empty region.
2069 uint space_id = src_space_id + 1;
2070 assert(space_id < last_space_id, "not enough spaces");
2071
2072 for (/* empty */; space_id < last_space_id; ++space_id) {
2073 HeapWord* bottom = _space_info[space_id].space()->bottom();
2074 HeapWord* top = _space_info[space_id].space()->top();
2075 // Skip empty space
2076 if (bottom == top) {
2077 continue;
2078 }
2079
2080 // Identify the first region that contains live words in this space
2081 size_t cur_region = sd.addr_to_region_idx(bottom);
2082 size_t end_region = sd.addr_to_region_idx(sd.region_align_up(top));
2083
2084 for (/* empty */ ; cur_region < end_region; ++cur_region) {
2085 RegionData* cur = sd.region(cur_region);
2086 if (cur->live_obj_size() > 0) {
2087 HeapWord* region_start_addr = sd.region_to_addr(cur_region);
2088
2089 src_space_id = SpaceId(space_id);
2090 src_space_top = top;
2091 closure.set_source(region_start_addr);
2092 return cur_region;
2093 }
2094 }
2095 }
2096
2097 ShouldNotReachHere();
2098 }
2099
2100 HeapWord* PSParallelCompact::partial_obj_end(HeapWord* region_start_addr) {
2101 ParallelCompactData& sd = summary_data();
2102 assert(sd.is_region_aligned(region_start_addr), "precondition");
2103
2104 // Use per-region partial_obj_size to locate the end of the obj, that extends
2105 // to region_start_addr.
2106 size_t start_region_idx = sd.addr_to_region_idx(region_start_addr);
2107 size_t end_region_idx = sd.region_count();
2108 size_t accumulated_size = 0;
2109 for (size_t region_idx = start_region_idx; region_idx < end_region_idx; ++region_idx) {
2110 size_t cur_partial_obj_size = sd.region(region_idx)->partial_obj_size();
2111 accumulated_size += cur_partial_obj_size;
2112 if (cur_partial_obj_size != ParallelCompactData::RegionSize) {
2113 break;
2114 }
2115 }
2116 return region_start_addr + accumulated_size;
2117 }
2118
2119 // Use region_idx as the destination region, and evacuate all live objs on its
2120 // source regions to this destination region.
2121 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2122 {
2123 ParMarkBitMap* const bitmap = mark_bitmap();
2124 ParallelCompactData& sd = summary_data();
2125 RegionData* const region_ptr = sd.region(region_idx);
2126
2127 // Get the source region and related info.
2128 size_t src_region_idx = region_ptr->source_region();
2129 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2130 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2131 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2132
2133 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2134
2135 // Adjust src_region_idx to prepare for decrementing destination counts (the
2136 // destination count is not decremented when a region is copied to itself).
2137 if (src_region_idx == region_idx) {
2138 src_region_idx += 1;
2139 }
2140
2141 // source-region:
2142 //
2143 // **********
2144 // | ~~~ |
2145 // **********
2146 // ^
2147 // |-- closure.source() / first_src_addr
2148 //
2149 //
2150 // ~~~ : live words
2151 //
2152 // destination-region:
2153 //
2154 // **********
2155 // | |
2156 // **********
2157 // ^
2158 // |-- region-start
2159 if (bitmap->is_unmarked(closure.source())) {
2160 // An object overflows the previous destination region, so this
2161 // destination region should copy the remainder of the object or as much as
2162 // will fit.
2163 HeapWord* const old_src_addr = closure.source();
2164 {
2165 HeapWord* region_start = sd.region_align_down(closure.source());
2166 HeapWord* obj_start = bitmap->find_obj_beg_reverse(region_start, closure.source());
2167 HeapWord* obj_end;
2168 if (obj_start != closure.source()) {
2169 assert(bitmap->is_marked(obj_start), "inv");
2170 // Found the actual obj-start, try to find the obj-end using either
2171 // size() if this obj is completely contained in the current region.
2172 HeapWord* next_region_start = region_start + ParallelCompactData::RegionSize;
2173 HeapWord* partial_obj_start = (next_region_start >= src_space_top)
2174 ? nullptr
2175 : sd.addr_to_region_ptr(next_region_start)->partial_obj_addr();
2176 // This obj extends to next region iff partial_obj_addr of the *next*
2177 // region is the same as obj-start.
2178 if (partial_obj_start == obj_start) {
2179 // This obj extends to next region.
2180 obj_end = partial_obj_end(next_region_start);
2181 } else {
2182 // Completely contained in this region; safe to use size().
2183 obj_end = obj_start + cast_to_oop(obj_start)->size();
2184 }
2185 } else {
2186 // This obj extends to current region.
2187 obj_end = partial_obj_end(region_start);
2188 }
2189 size_t partial_obj_size = pointer_delta(obj_end, closure.source());
2190 closure.copy_partial_obj(partial_obj_size);
2191 }
2192
2193 if (closure.is_full()) {
2194 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2195 closure.complete_region(dest_addr, region_ptr);
2196 return;
2197 }
2198
2199 // Finished copying without using up the current destination-region
2200 HeapWord* const end_addr = sd.region_align_down(closure.source());
2201 if (sd.region_align_down(old_src_addr) != end_addr) {
2202 assert(sd.region_align_up(old_src_addr) == end_addr, "only one region");
2203 // The partial object was copied from more than one source region.
2204 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2205
2206 // Move to the next source region, possibly switching spaces as well. All
2207 // args except end_addr may be modified.
2208 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2209 }
2210 }
2211
2212 // Handle the rest obj-by-obj, where we know obj-start.
2213 do {
2214 HeapWord* cur_addr = closure.source();
2215 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2216 src_space_top);
2217 // To handle the case where the final obj in source region extends to next region.
2218 HeapWord* final_obj_start = (end_addr == src_space_top)
2219 ? nullptr
2220 : sd.addr_to_region_ptr(end_addr)->partial_obj_addr();
2221 // Apply closure on objs inside [cur_addr, end_addr)
2222 do {
2223 cur_addr = bitmap->find_obj_beg(cur_addr, end_addr);
2224 if (cur_addr == end_addr) {
2225 break;
2226 }
2227 size_t obj_size;
2228 if (final_obj_start == cur_addr) {
2229 obj_size = pointer_delta(partial_obj_end(end_addr), cur_addr);
2230 } else {
2231 // This obj doesn't extend into next region; size() is safe to use.
2232 obj_size = cast_to_oop(cur_addr)->size();
2233 }
2234 closure.do_addr(cur_addr, obj_size);
2235 cur_addr += obj_size;
2236 } while (cur_addr < end_addr && !closure.is_full());
2237
2238 if (closure.is_full()) {
2239 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2240 closure.complete_region(dest_addr, region_ptr);
2241 return;
2242 }
2243
2244 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2245
2246 // Move to the next source region, possibly switching spaces as well. All
2247 // args except end_addr may be modified.
2248 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2249 } while (true);
2250 }
2251
2252 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
2253 {
2254 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2255 fill_region(cm, cl, region_idx);
2256 }
2257
2258 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
2259 {
2260 // Get a shadow region first
2261 ParallelCompactData& sd = summary_data();
2262 RegionData* const region_ptr = sd.region(region_idx);
2263 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
2264 // The InvalidShadow return value indicates the corresponding heap region is available,
2265 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
2266 // MoveAndUpdateShadowClosure to fill the acquired shadow region.
2267 if (shadow_region == ParCompactionManager::InvalidShadow) {
2268 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2269 region_ptr->shadow_to_normal();
2270 return fill_region(cm, cl, region_idx);
2271 } else {
2272 MoveAndUpdateShadowClosure cl(mark_bitmap(), region_idx, shadow_region);
2273 return fill_region(cm, cl, region_idx);
2274 }
2275 }
2276
2277 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
2278 {
2279 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
2280 }
2281
2282 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx)
2283 {
2284 size_t next = cm->next_shadow_region();
2285 ParallelCompactData& sd = summary_data();
2286 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
2287 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2288
2289 while (next < old_new_top) {
2290 if (sd.region(next)->mark_shadow()) {
2291 region_idx = next;
2292 return true;
2293 }
2294 next = cm->move_next_shadow_region_by(active_gc_threads);
2295 }
2296
2297 return false;
2298 }
2299
2300 // The shadow region is an optimization to address region dependencies in full GC. The basic
2301 // idea is making more regions available by temporally storing their live objects in empty
2302 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
2303 // GC threads need not wait destination regions to be available before processing sources.
2304 //
2305 // A typical workflow would be:
2306 // After draining its own stack and failing to steal from others, a GC worker would pick an
2307 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
2308 // the shadow region by copying live objects from source regions of the unavailable one. Once
2309 // the unavailable region becomes available, the data in the shadow region will be copied back.
2310 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
2311 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
2312 {
2313 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2314
2315 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2316 SpaceInfo* const space_info = _space_info + id;
2317 MutableSpace* const space = space_info->space();
2318
2319 const size_t beg_region =
2320 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
2321 const size_t end_region =
2322 sd.addr_to_region_idx(sd.region_align_down(space->end()));
2323
2324 for (size_t cur = beg_region; cur < end_region; ++cur) {
2325 ParCompactionManager::push_shadow_region(cur);
2326 }
2327 }
2328
2329 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
2330 for (uint i = 0; i < parallel_gc_threads; i++) {
2331 ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i);
2332 cm->set_next_shadow_region(beg_region + i);
2333 }
2334 }
2335
2336 void MoveAndUpdateClosure::copy_partial_obj(size_t partial_obj_size)
2337 {
2338 size_t words = MIN2(partial_obj_size, words_remaining());
2339
2340 // This test is necessary; if omitted, the pointer updates to a partial object
2341 // that crosses the dense prefix boundary could be overwritten.
2342 if (source() != copy_destination()) {
2343 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2344 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2345 }
2346 update_state(words);
2347 }
2348
2349 void MoveAndUpdateClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2350 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
2351 region_ptr->set_completed();
2352 }
2353
2354 void MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
2355 assert(destination() != nullptr, "sanity");
2356 _source = addr;
2357
2358 // The start_array must be updated even if the object is not moving.
2359 if (_start_array != nullptr) {
2360 _start_array->update_for_block(destination(), destination() + words);
2361 }
2362
2363 // Avoid overflow
2364 words = MIN2(words, words_remaining());
2365 assert(words > 0, "inv");
2366
2367 if (copy_destination() != source()) {
2368 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2369 assert(source() != destination(), "inv");
2370 assert(FullGCForwarding::is_forwarded(cast_to_oop(source())), "inv");
2371 assert(FullGCForwarding::forwardee(cast_to_oop(source())) == cast_to_oop(destination()), "inv");
2372 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2373 cast_to_oop(copy_destination())->init_mark();
2374 }
2375
2376 update_state(words);
2377 }
2378
2379 void MoveAndUpdateShadowClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2380 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
2381 // Record the shadow region index
2382 region_ptr->set_shadow_region(_shadow);
2383 // Mark the shadow region as filled to indicate the data is ready to be
2384 // copied back
2385 region_ptr->mark_filled();
2386 // Try to copy the content of the shadow region back to its corresponding
2387 // heap region if available; the GC thread that decreases the destination
2388 // count to zero will do the copying otherwise (see
2389 // PSParallelCompact::decrement_destination_counts).
2390 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
2391 region_ptr->set_completed();
2392 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
2393 ParCompactionManager::push_shadow_region_mt_safe(_shadow);
2394 }
2395 }