1 /*
2 * Copyright (c) 2005, 2026, 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 "cppstdlib/new.hpp"
34 #include "gc/parallel/objectStartArray.inline.hpp"
35 #include "gc/parallel/parallelArguments.hpp"
36 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
37 #include "gc/parallel/parMarkBitMap.inline.hpp"
38 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
39 #include "gc/parallel/psCompactionManager.inline.hpp"
40 #include "gc/parallel/psOldGen.hpp"
41 #include "gc/parallel/psParallelCompact.inline.hpp"
42 #include "gc/parallel/psPromotionManager.inline.hpp"
43 #include "gc/parallel/psRootType.hpp"
44 #include "gc/parallel/psScavenge.hpp"
45 #include "gc/parallel/psStringDedup.hpp"
46 #include "gc/parallel/psYoungGen.hpp"
47 #include "gc/shared/classUnloadingContext.hpp"
48 #include "gc/shared/collectedHeap.inline.hpp"
49 #include "gc/shared/fullGCForwarding.inline.hpp"
50 #include "gc/shared/gcCause.hpp"
51 #include "gc/shared/gcHeapSummary.hpp"
52 #include "gc/shared/gcId.hpp"
53 #include "gc/shared/gcLocker.hpp"
54 #include "gc/shared/gcTimer.hpp"
55 #include "gc/shared/gcTrace.hpp"
56 #include "gc/shared/gcTraceTime.inline.hpp"
57 #include "gc/shared/gcVMOperations.hpp"
58 #include "gc/shared/isGCActiveMark.hpp"
59 #include "gc/shared/oopStorage.inline.hpp"
60 #include "gc/shared/oopStorageSet.inline.hpp"
61 #include "gc/shared/oopStorageSetParState.inline.hpp"
62 #include "gc/shared/parallelCleaning.hpp"
63 #include "gc/shared/preservedMarks.inline.hpp"
64 #include "gc/shared/referencePolicy.hpp"
65 #include "gc/shared/referenceProcessor.hpp"
66 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
67 #include "gc/shared/spaceDecorator.hpp"
68 #include "gc/shared/taskTerminator.hpp"
69 #include "gc/shared/weakProcessor.inline.hpp"
70 #include "gc/shared/workerPolicy.hpp"
71 #include "gc/shared/workerThread.hpp"
72 #include "gc/shared/workerUtils.hpp"
73 #include "logging/log.hpp"
74 #include "memory/iterator.inline.hpp"
75 #include "memory/memoryReserver.hpp"
76 #include "memory/metaspaceUtils.hpp"
77 #include "memory/resourceArea.hpp"
78 #include "memory/universe.hpp"
79 #include "nmt/memTracker.hpp"
80 #include "oops/access.inline.hpp"
81 #include "oops/instanceClassLoaderKlass.inline.hpp"
82 #include "oops/instanceKlass.inline.hpp"
83 #include "oops/instanceMirrorKlass.inline.hpp"
84 #include "oops/methodData.hpp"
85 #include "oops/objArrayKlass.inline.hpp"
86 #include "oops/oop.inline.hpp"
87 #include "runtime/handles.inline.hpp"
88 #include "runtime/java.hpp"
89 #include "runtime/safepoint.hpp"
90 #include "runtime/threads.hpp"
91 #include "runtime/vmThread.hpp"
92 #include "services/memoryService.hpp"
93 #include "utilities/align.hpp"
94 #include "utilities/debug.hpp"
95 #include "utilities/events.hpp"
96 #include "utilities/formatBuffer.hpp"
97 #include "utilities/macros.hpp"
98 #include "utilities/stack.inline.hpp"
99 #if INCLUDE_JVMCI
100 #include "jvmci/jvmci.hpp"
101 #endif
102
103 #include <math.h>
104
105 // All sizes are in HeapWords.
106 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
107 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
108 static_assert(ParallelCompactData::RegionSize >= BitsPerWord, "region-start bit word-aligned");
109 const size_t ParallelCompactData::RegionSizeBytes =
110 RegionSize << LogHeapWordSize;
111 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
112 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
113 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
114
115 const ParallelCompactData::RegionData::region_sz_t
116 ParallelCompactData::RegionData::dc_shift = 27;
117
118 const ParallelCompactData::RegionData::region_sz_t
119 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
120
121 const ParallelCompactData::RegionData::region_sz_t
122 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
123
124 const ParallelCompactData::RegionData::region_sz_t
125 ParallelCompactData::RegionData::los_mask = ~dc_mask;
126
127 const ParallelCompactData::RegionData::region_sz_t
128 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
129
130 const ParallelCompactData::RegionData::region_sz_t
131 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
132
133 bool ParallelCompactData::RegionData::is_clear() {
134 return (_destination == nullptr) &&
135 (_source_region == 0) &&
136 (_partial_obj_addr == nullptr) &&
137 (_partial_obj_size == 0) &&
138 (dc_and_los() == 0) &&
139 (shadow_state() == 0);
140 }
141
142 #ifdef ASSERT
143 void ParallelCompactData::RegionData::verify_clear() {
144 assert(_destination == nullptr, "inv");
145 assert(_source_region == 0, "inv");
146 assert(_partial_obj_addr == nullptr, "inv");
147 assert(_partial_obj_size == 0, "inv");
148 assert(dc_and_los() == 0, "inv");
149 assert(shadow_state() == 0, "inv");
150 }
151 #endif
152
153 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
154
155 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
156 ReferenceProcessor* PSParallelCompact::_ref_processor = nullptr;
157
158 void SplitInfo::record(size_t split_region_idx, HeapWord* split_point, size_t preceding_live_words) {
159 assert(split_region_idx != 0, "precondition");
160
161 // Obj denoted by split_point will be deferred to the next space.
162 assert(split_point != nullptr, "precondition");
163
164 const ParallelCompactData& sd = PSParallelCompact::summary_data();
165
166 PSParallelCompact::RegionData* split_region_ptr = sd.region(split_region_idx);
167 assert(preceding_live_words < split_region_ptr->data_size(), "inv");
168
169 HeapWord* preceding_destination = split_region_ptr->destination();
170 assert(preceding_destination != nullptr, "inv");
171
172 // How many regions does the preceding part occupy
173 uint preceding_destination_count;
174 if (preceding_live_words == 0) {
175 preceding_destination_count = 0;
176 } else {
177 // -1 so that the ending address doesn't fall on the region-boundary
178 if (sd.region_align_down(preceding_destination) ==
179 sd.region_align_down(preceding_destination + preceding_live_words - 1)) {
180 preceding_destination_count = 1;
181 } else {
182 preceding_destination_count = 2;
183 }
184 }
185
186 _split_region_idx = split_region_idx;
187 _split_point = split_point;
188 _preceding_live_words = preceding_live_words;
189 _preceding_destination = preceding_destination;
190 _preceding_destination_count = preceding_destination_count;
191 }
192
193 void SplitInfo::clear()
194 {
195 _split_region_idx = 0;
196 _split_point = nullptr;
197 _preceding_live_words = 0;
198 _preceding_destination = nullptr;
199 _preceding_destination_count = 0;
200 assert(!is_valid(), "sanity");
201 }
202
203 #ifdef ASSERT
204 void SplitInfo::verify_clear()
205 {
206 assert(_split_region_idx == 0, "not clear");
207 assert(_split_point == nullptr, "not clear");
208 assert(_preceding_live_words == 0, "not clear");
209 assert(_preceding_destination == nullptr, "not clear");
210 assert(_preceding_destination_count == 0, "not clear");
211 }
212 #endif // #ifdef ASSERT
213
214
215 void PSParallelCompact::print_on(outputStream* st) {
216 _mark_bitmap.print_on(st);
217 }
218
219 ParallelCompactData::ParallelCompactData() :
220 _heap_start(nullptr),
221 DEBUG_ONLY(_heap_end(nullptr) COMMA)
222 _region_vspace(nullptr),
223 _reserved_byte_size(0),
224 _region_data(nullptr),
225 _region_count(0) {}
226
227 bool ParallelCompactData::initialize(MemRegion reserved_heap)
228 {
229 _heap_start = reserved_heap.start();
230 const size_t heap_size = reserved_heap.word_size();
231 DEBUG_ONLY(_heap_end = _heap_start + heap_size;)
232
233 assert(region_align_down(_heap_start) == _heap_start,
234 "region start not aligned");
235 assert(is_aligned(heap_size, RegionSize), "precondition");
236
237 const size_t count = heap_size >> Log2RegionSize;
238 const size_t raw_bytes = count * sizeof(RegionData);
239 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
240 const size_t granularity = os::vm_allocation_granularity();
241 const size_t rs_align = MAX2(page_sz, granularity);
242
243 _reserved_byte_size = align_up(raw_bytes, rs_align);
244
245 ReservedSpace rs = MemoryReserver::reserve(_reserved_byte_size,
246 rs_align,
247 page_sz,
248 mtGC);
249
250 if (!rs.is_reserved()) {
251 // Failed to reserve memory.
252 return false;
253 }
254
255 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, rs.base(),
256 rs.size(), page_sz);
257
258 MemTracker::record_virtual_memory_tag(rs, mtGC);
259
260 PSVirtualSpace* region_vspace = new PSVirtualSpace(rs, page_sz);
261
262 if (!region_vspace->expand_by(_reserved_byte_size)) {
263 // Failed to commit memory.
264
265 delete region_vspace;
266
267 // Release memory reserved in the space.
268 MemoryReserver::release(rs);
269
270 return false;
271 }
272
273 _region_vspace = region_vspace;
274 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
275 _region_count = count;
276 return true;
277 }
278
279 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
280 assert(beg_region <= _region_count, "beg_region out of range");
281 assert(end_region <= _region_count, "end_region out of range");
282
283 const size_t region_cnt = end_region - beg_region;
284 for (size_t i = beg_region; i < end_region; i++) {
285 ::new (&_region_data[i]) RegionData{};
286 }
287 }
288
289 // The total live words on src_region would overflow the target space, so find
290 // the overflowing object and record the split point. The invariant is that an
291 // obj should not cross space boundary.
292 HeapWord* ParallelCompactData::summarize_split_space(size_t src_region,
293 SplitInfo& split_info,
294 HeapWord* const destination,
295 HeapWord* const target_end,
296 HeapWord** target_next) {
297 assert(destination <= target_end, "sanity");
298 assert(destination + _region_data[src_region].data_size() > target_end,
299 "region should not fit into target space");
300 assert(is_region_aligned(target_end), "sanity");
301
302 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
303
304 if (destination + partial_obj_size > target_end) {
305 assert(partial_obj_size > 0, "inv");
306 // The overflowing obj is from a previous region.
307 //
308 // source-regions:
309 //
310 // ***************
311 // | A|AA |
312 // ***************
313 // ^
314 // | split-point
315 //
316 // dest-region:
317 //
318 // ********
319 // |~~~~A |
320 // ********
321 // ^^
322 // || target-space-end
323 // |
324 // | destination
325 //
326 // AAA would overflow target-space.
327 //
328 HeapWord* overflowing_obj = _region_data[src_region].partial_obj_addr();
329 size_t split_region = addr_to_region_idx(overflowing_obj);
330
331 // The number of live words before the overflowing object on this split region
332 size_t preceding_live_words;
333 if (is_region_aligned(overflowing_obj)) {
334 preceding_live_words = 0;
335 } else {
336 // Words accounted by the overflowing object on the split region
337 size_t overflowing_size = pointer_delta(region_align_up(overflowing_obj), overflowing_obj);
338 preceding_live_words = region(split_region)->data_size() - overflowing_size;
339 }
340
341 split_info.record(split_region, overflowing_obj, preceding_live_words);
342
343 // The [overflowing_obj, src_region_start) part has been accounted for, so
344 // must move back the new_top, now that this overflowing obj is deferred.
345 HeapWord* new_top = destination - pointer_delta(region_to_addr(src_region), overflowing_obj);
346
347 // If the overflowing obj was relocated to its original destination,
348 // those destination regions would have their source_region set. Now that
349 // this overflowing obj is relocated somewhere else, reset the
350 // source_region.
351 {
352 size_t range_start = addr_to_region_idx(region_align_up(new_top));
353 size_t range_end = addr_to_region_idx(region_align_up(destination));
354 for (size_t i = range_start; i < range_end; ++i) {
355 region(i)->set_source_region(0);
356 }
357 }
358
359 // Update new top of target space
360 *target_next = new_top;
361
362 return overflowing_obj;
363 }
364
365 // Obj-iteration to locate the overflowing obj
366 HeapWord* region_start = region_to_addr(src_region);
367 HeapWord* region_end = region_start + RegionSize;
368 HeapWord* cur_addr = region_start + partial_obj_size;
369 size_t live_words = partial_obj_size;
370
371 while (true) {
372 assert(cur_addr < region_end, "inv");
373 cur_addr = PSParallelCompact::mark_bitmap()->find_obj_beg(cur_addr, region_end);
374 // There must be an overflowing obj in this region
375 assert(cur_addr < region_end, "inv");
376
377 oop obj = cast_to_oop(cur_addr);
378 size_t obj_size = obj->size();
379 if (destination + live_words + obj_size > target_end) {
380 // Found the overflowing obj
381 split_info.record(src_region, cur_addr, live_words);
382 *target_next = destination + live_words;
383 return cur_addr;
384 }
385
386 live_words += obj_size;
387 cur_addr += obj_size;
388 }
389 }
390
391 size_t ParallelCompactData::live_words_in_space(const MutableSpace* space,
392 HeapWord** full_region_prefix_end) {
393 size_t cur_region = addr_to_region_idx(space->bottom());
394 const size_t end_region = addr_to_region_idx(region_align_up(space->top()));
395 size_t live_words = 0;
396 if (full_region_prefix_end == nullptr) {
397 for (/* empty */; cur_region < end_region; ++cur_region) {
398 live_words += _region_data[cur_region].data_size();
399 }
400 } else {
401 bool first_set = false;
402 for (/* empty */; cur_region < end_region; ++cur_region) {
403 size_t live_words_in_region = _region_data[cur_region].data_size();
404 if (!first_set && live_words_in_region < RegionSize) {
405 *full_region_prefix_end = region_to_addr(cur_region);
406 first_set = true;
407 }
408 live_words += live_words_in_region;
409 }
410 if (!first_set) {
411 // All regions are full of live objs.
412 assert(is_region_aligned(space->top()), "inv");
413 *full_region_prefix_end = space->top();
414 }
415 assert(*full_region_prefix_end != nullptr, "postcondition");
416 assert(is_region_aligned(*full_region_prefix_end), "inv");
417 assert(*full_region_prefix_end >= space->bottom(), "in-range");
418 assert(*full_region_prefix_end <= space->top(), "in-range");
419 }
420 return live_words;
421 }
422
423 bool ParallelCompactData::summarize(SplitInfo& split_info,
424 HeapWord* source_beg, HeapWord* source_end,
425 HeapWord** source_next,
426 HeapWord* target_beg, HeapWord* target_end,
427 HeapWord** target_next)
428 {
429 HeapWord* const source_next_val = source_next == nullptr ? nullptr : *source_next;
430 log_develop_trace(gc, compaction)(
431 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
432 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
433 p2i(source_beg), p2i(source_end), p2i(source_next_val),
434 p2i(target_beg), p2i(target_end), p2i(*target_next));
435
436 size_t cur_region = addr_to_region_idx(source_beg);
437 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
438
439 HeapWord *dest_addr = target_beg;
440 for (/* empty */; cur_region < end_region; cur_region++) {
441 size_t words = _region_data[cur_region].data_size();
442
443 // Skip empty ones
444 if (words == 0) {
445 continue;
446 }
447
448 if (split_info.is_split(cur_region)) {
449 assert(words > split_info.preceding_live_words(), "inv");
450 words -= split_info.preceding_live_words();
451 }
452
453 _region_data[cur_region].set_destination(dest_addr);
454
455 // If cur_region does not fit entirely into the target space, find a point
456 // at which the source space can be 'split' so that part is copied to the
457 // target space and the rest is copied elsewhere.
458 if (dest_addr + words > target_end) {
459 assert(source_next != nullptr, "source_next is null when splitting");
460 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
461 target_end, target_next);
462 return false;
463 }
464
465 uint destination_count = split_info.is_split(cur_region)
466 ? split_info.preceding_destination_count()
467 : 0;
468
469 HeapWord* const last_addr = dest_addr + words - 1;
470 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
471 const size_t dest_region_2 = addr_to_region_idx(last_addr);
472
473 // Initially assume that the destination regions will be the same and
474 // adjust the value below if necessary. Under this assumption, if
475 // cur_region == dest_region_2, then cur_region will be compacted
476 // completely into itself.
477 destination_count += cur_region == dest_region_2 ? 0 : 1;
478 if (dest_region_1 != dest_region_2) {
479 // Destination regions differ; adjust destination_count.
480 destination_count += 1;
481 // Data from cur_region will be copied to the start of dest_region_2.
482 _region_data[dest_region_2].set_source_region(cur_region);
483 } else if (is_region_aligned(dest_addr)) {
484 // Data from cur_region will be copied to the start of the destination
485 // region.
486 _region_data[dest_region_1].set_source_region(cur_region);
487 }
488
489 _region_data[cur_region].set_destination_count(destination_count);
490 dest_addr += words;
491 }
492
493 *target_next = dest_addr;
494 return true;
495 }
496
497 #ifdef ASSERT
498 void ParallelCompactData::verify_clear() {
499 for (uint cur_idx = 0; cur_idx < region_count(); ++cur_idx) {
500 if (!region(cur_idx)->is_clear()) {
501 log_warning(gc)("Uncleared Region: %u", cur_idx);
502 region(cur_idx)->verify_clear();
503 }
504 }
505 }
506 #endif // #ifdef ASSERT
507
508 STWGCTimer PSParallelCompact::_gc_timer;
509 ParallelOldTracer PSParallelCompact::_gc_tracer;
510 elapsedTimer PSParallelCompact::_accumulated_time;
511 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
512 CollectorCounters* PSParallelCompact::_counters = nullptr;
513 ParMarkBitMap PSParallelCompact::_mark_bitmap;
514 ParallelCompactData PSParallelCompact::_summary_data;
515
516 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
517
518 class PCAdjustPointerClosureNew: public BasicOopIterateClosure {
519 template <typename T>
520 void do_oop_work(T* p) { PSParallelCompact::adjust_pointer(p); }
521
522 public:
523 virtual void do_oop(oop* p) { do_oop_work(p); }
524 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
525
526 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
527 };
528
529 static PCAdjustPointerClosureNew pc_adjust_pointer_closure;
530
531 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
532
533 void PSParallelCompact::post_initialize() {
534 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
535 _span_based_discoverer.set_span(heap->reserved_region());
536 _ref_processor =
537 new ReferenceProcessor(&_span_based_discoverer,
538 ParallelGCThreads, // mt processing degree
539 ParallelGCThreads, // mt discovery degree
540 false, // concurrent_discovery
541 &_is_alive_closure); // non-header is alive closure
542
543 _counters = new CollectorCounters("Parallel full collection pauses", 1);
544
545 // Initialize static fields in ParCompactionManager.
546 ParCompactionManager::initialize(mark_bitmap());
547 }
548
549 bool PSParallelCompact::initialize_aux_data() {
550 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
551 MemRegion mr = heap->reserved_region();
552 assert(mr.byte_size() != 0, "heap should be reserved");
553
554 initialize_space_info();
555
556 if (!_mark_bitmap.initialize(mr)) {
557 vm_shutdown_during_initialization(
558 err_msg("Unable to allocate %zuKB bitmaps for parallel "
559 "garbage collection for the requested %zuKB heap.",
560 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
561 return false;
562 }
563
564 if (!_summary_data.initialize(mr)) {
565 vm_shutdown_during_initialization(
566 err_msg("Unable to allocate %zuKB card tables for parallel "
567 "garbage collection for the requested %zuKB heap.",
568 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
569 return false;
570 }
571
572 return true;
573 }
574
575 void PSParallelCompact::initialize_space_info()
576 {
577 memset(&_space_info, 0, sizeof(_space_info));
578
579 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
580 PSYoungGen* young_gen = heap->young_gen();
581
582 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
583 _space_info[eden_space_id].set_space(young_gen->eden_space());
584 _space_info[from_space_id].set_space(young_gen->from_space());
585 _space_info[to_space_id].set_space(young_gen->to_space());
586
587 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
588 }
589
590 void
591 PSParallelCompact::clear_data_covering_space(SpaceId id)
592 {
593 // At this point, top is the value before GC, new_top() is the value that will
594 // be set at the end of GC. The marking bitmap is cleared to top; nothing
595 // should be marked above top. The summary data is cleared to the larger of
596 // top & new_top.
597 MutableSpace* const space = _space_info[id].space();
598 HeapWord* const bot = space->bottom();
599 HeapWord* const top = space->top();
600 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
601
602 _mark_bitmap.clear_range(bot, top);
603
604 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
605 const size_t end_region =
606 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
607 _summary_data.clear_range(beg_region, end_region);
608
609 // Clear the data used to 'split' regions.
610 SplitInfo& split_info = _space_info[id].split_info();
611 if (split_info.is_valid()) {
612 split_info.clear();
613 }
614 DEBUG_ONLY(split_info.verify_clear();)
615 }
616
617 void PSParallelCompact::pre_compact()
618 {
619 // Update the from & to space pointers in space_info, since they are swapped
620 // at each young gen gc. Do the update unconditionally (even though a
621 // promotion failure does not swap spaces) because an unknown number of young
622 // collections will have swapped the spaces an unknown number of times.
623 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
624 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
625 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
626 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
627
628 heap->increment_total_collections(true);
629
630 CodeCache::on_gc_marking_cycle_start();
631
632 heap->print_before_gc();
633 heap->trace_heap_before_gc(&_gc_tracer);
634
635 // Fill in TLABs
636 heap->ensure_parsability(true); // retire TLABs
637
638 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
639 Universe::verify("Before GC");
640 }
641
642 DEBUG_ONLY(mark_bitmap()->verify_clear();)
643 DEBUG_ONLY(summary_data().verify_clear();)
644 }
645
646 void PSParallelCompact::post_compact()
647 {
648 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
649 ParCompactionManager::remove_all_shadow_regions();
650
651 CodeCache::on_gc_marking_cycle_finish();
652 CodeCache::arm_all_nmethods();
653
654 // Need to clear claim bits for the next full-gc (marking and adjust-pointers).
655 ClassLoaderDataGraph::clear_claimed_marks();
656
657 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
658 // Clear the marking bitmap, summary data and split info.
659 clear_data_covering_space(SpaceId(id));
660 {
661 MutableSpace* space = _space_info[id].space();
662 HeapWord* top = space->top();
663 HeapWord* new_top = _space_info[id].new_top();
664 if (ZapUnusedHeapArea && new_top < top) {
665 space->mangle_region(MemRegion(new_top, top));
666 }
667 // Update top(). Must be done after clearing the bitmap and summary data.
668 space->set_top(new_top);
669 }
670 }
671
672 #ifdef ASSERT
673 {
674 mark_bitmap()->verify_clear();
675 summary_data().verify_clear();
676 }
677 #endif
678
679 ParCompactionManager::flush_all_string_dedup_requests();
680
681 MutableSpace* const eden_space = _space_info[eden_space_id].space();
682 MutableSpace* const from_space = _space_info[from_space_id].space();
683 MutableSpace* const to_space = _space_info[to_space_id].space();
684
685 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
686 bool eden_empty = eden_space->is_empty();
687
688 // Update heap occupancy information which is used as input to the soft ref
689 // clearing policy at the next gc.
690 Universe::heap()->update_capacity_and_used_at_gc();
691
692 bool young_gen_empty = eden_empty && from_space->is_empty() &&
693 to_space->is_empty();
694
695 PSCardTable* ct = heap->card_table();
696 MemRegion old_mr = heap->old_gen()->committed();
697 if (young_gen_empty) {
698 ct->clear_MemRegion(old_mr);
699 } else {
700 ct->dirty_MemRegion(old_mr);
701 }
702
703 heap->prune_scavengable_nmethods();
704
705 #if COMPILER2_OR_JVMCI
706 DerivedPointerTable::update_pointers();
707 #endif
708
709 // Signal that we have completed a visit to all live objects.
710 Universe::heap()->record_whole_heap_examined_timestamp();
711 }
712
713 HeapWord* PSParallelCompact::compute_dense_prefix_for_old_space(MutableSpace* old_space,
714 HeapWord* full_region_prefix_end) {
715 const size_t region_size = ParallelCompactData::RegionSize;
716 const ParallelCompactData& sd = summary_data();
717
718 // Iteration starts with the region *after* the full-region-prefix-end.
719 const RegionData* const start_region = sd.addr_to_region_ptr(full_region_prefix_end);
720 // If final region is not full, iteration stops before that region,
721 // because fill_dense_prefix_end assumes that prefix_end <= top.
722 const RegionData* const end_region = sd.addr_to_region_ptr(old_space->top());
723 assert(start_region <= end_region, "inv");
724
725 size_t max_waste = old_space->capacity_in_words() * (MarkSweepDeadRatio / 100.0);
726 const RegionData* cur_region = start_region;
727 for (/* empty */; cur_region < end_region; ++cur_region) {
728 assert(region_size >= cur_region->data_size(), "inv");
729 size_t dead_size = region_size - cur_region->data_size();
730 if (max_waste < dead_size) {
731 break;
732 }
733 max_waste -= dead_size;
734 }
735
736 HeapWord* const prefix_end = sd.region_to_addr(cur_region);
737 assert(sd.is_region_aligned(prefix_end), "postcondition");
738 assert(prefix_end >= full_region_prefix_end, "in-range");
739 assert(prefix_end <= old_space->top(), "in-range");
740 return prefix_end;
741 }
742
743 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) {
744 // Comparing two sizes to decide if filling is required:
745 //
746 // The size of the filler (min-obj-size) is 2 heap words with the default
747 // MinObjAlignment, since both markword and klass take 1 heap word.
748 // With +UseCompactObjectHeaders, the minimum filler size is only one word,
749 // because the Klass* gets encoded in the mark-word.
750 //
751 // The size of the gap (if any) right before dense-prefix-end is
752 // MinObjAlignment.
753 //
754 // Need to fill in the gap only if it's smaller than min-obj-size, and the
755 // filler obj will extend to next region.
756
757 if (MinObjAlignment >= checked_cast<int>(CollectedHeap::min_fill_size())) {
758 return;
759 }
760
761 assert(!UseCompactObjectHeaders, "Compact headers can allocate small objects");
762 assert(CollectedHeap::min_fill_size() == 2, "inv");
763 HeapWord* const dense_prefix_end = dense_prefix(id);
764 assert(_summary_data.is_region_aligned(dense_prefix_end), "precondition");
765 assert(dense_prefix_end <= space(id)->top(), "precondition");
766 if (dense_prefix_end == space(id)->top()) {
767 // Must not have single-word gap right before prefix-end/top.
768 return;
769 }
770 RegionData* const region_after_dense_prefix = _summary_data.addr_to_region_ptr(dense_prefix_end);
771
772 if (region_after_dense_prefix->partial_obj_size() != 0 ||
773 _mark_bitmap.is_marked(dense_prefix_end)) {
774 // The region after the dense prefix starts with live bytes.
775 return;
776 }
777
778 HeapWord* block_start = start_array(id)->block_start_reaching_into_card(dense_prefix_end);
779 if (block_start == dense_prefix_end - 1) {
780 assert(!_mark_bitmap.is_marked(block_start), "inv");
781 // There is exactly one heap word gap right before the dense prefix end, so we need a filler object.
782 // The filler object will extend into region_after_dense_prefix.
783 const size_t obj_len = 2; // min-fill-size
784 HeapWord* const obj_beg = dense_prefix_end - 1;
785 CollectedHeap::fill_with_object(obj_beg, obj_len);
786 _mark_bitmap.mark_obj(obj_beg);
787 _summary_data.addr_to_region_ptr(obj_beg)->add_live_obj(1);
788 region_after_dense_prefix->set_partial_obj_size(1);
789 region_after_dense_prefix->set_partial_obj_addr(obj_beg);
790 assert(start_array(id) != nullptr, "sanity");
791 start_array(id)->update_for_block(obj_beg, obj_beg + obj_len);
792 }
793 }
794
795 bool PSParallelCompact::check_maximum_compaction(bool should_do_max_compaction,
796 size_t total_live_words,
797 MutableSpace* const old_space,
798 HeapWord* full_region_prefix_end) {
799
800 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
801
802 // Check System.GC
803 bool is_max_on_system_gc = UseMaximumCompactionOnSystemGC
804 && GCCause::is_user_requested_gc(heap->gc_cause());
805
806 // Check if all live objs are too much for old-gen.
807 const bool is_old_gen_too_full = (total_live_words >= old_space->capacity_in_words());
808
809 // If all regions in old-gen are full
810 const bool is_region_full =
811 full_region_prefix_end >= _summary_data.region_align_down(old_space->top());
812
813 return should_do_max_compaction
814 || is_max_on_system_gc
815 || is_old_gen_too_full
816 || is_region_full;
817 }
818
819 void PSParallelCompact::summary_phase(bool should_do_max_compaction)
820 {
821 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
822
823 MutableSpace* const old_space = _space_info[old_space_id].space();
824 {
825 size_t total_live_words = 0;
826 HeapWord* full_region_prefix_end = nullptr;
827 {
828 // old-gen
829 size_t live_words = _summary_data.live_words_in_space(old_space,
830 &full_region_prefix_end);
831 total_live_words += live_words;
832 }
833 // young-gen
834 for (uint i = eden_space_id; i < last_space_id; ++i) {
835 const MutableSpace* space = _space_info[i].space();
836 size_t live_words = _summary_data.live_words_in_space(space);
837 total_live_words += live_words;
838 _space_info[i].set_new_top(space->bottom() + live_words);
839 _space_info[i].set_dense_prefix(space->bottom());
840 }
841
842 should_do_max_compaction = check_maximum_compaction(should_do_max_compaction,
843 total_live_words,
844 old_space,
845 full_region_prefix_end);
846 {
847 GCTraceTime(Info, gc, phases) tm("Summary Phase: expand", &_gc_timer);
848 // Try to expand old-gen in order to fit all live objs and waste.
849 size_t target_capacity_bytes = total_live_words * HeapWordSize
850 + old_space->capacity_in_bytes() * (MarkSweepDeadRatio / 100);
851 ParallelScavengeHeap::heap()->old_gen()->try_expand_till_size(target_capacity_bytes);
852 }
853
854 HeapWord* dense_prefix_end = should_do_max_compaction
855 ? full_region_prefix_end
856 : compute_dense_prefix_for_old_space(old_space,
857 full_region_prefix_end);
858 SpaceId id = old_space_id;
859 _space_info[id].set_dense_prefix(dense_prefix_end);
860
861 if (dense_prefix_end != old_space->bottom()) {
862 fill_dense_prefix_end(id);
863 }
864
865 // Compacting objs in [dense_prefix_end, old_space->top())
866 _summary_data.summarize(_space_info[id].split_info(),
867 dense_prefix_end, old_space->top(), nullptr,
868 dense_prefix_end, old_space->end(),
869 _space_info[id].new_top_addr());
870 }
871
872 // Summarize the remaining spaces in the young gen. The initial target space
873 // is the old gen. If a space does not fit entirely into the target, then the
874 // remainder is compacted into the space itself and that space becomes the new
875 // target.
876 SpaceId dst_space_id = old_space_id;
877 HeapWord* dst_space_end = old_space->end();
878 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
879 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
880 const MutableSpace* space = _space_info[id].space();
881 const size_t live = pointer_delta(_space_info[id].new_top(),
882 space->bottom());
883 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
884
885 if (live > 0 && live <= available) {
886 // All the live data will fit.
887 bool done = _summary_data.summarize(_space_info[id].split_info(),
888 space->bottom(), space->top(),
889 nullptr,
890 *new_top_addr, dst_space_end,
891 new_top_addr);
892 assert(done, "space must fit into old gen");
893
894 // Reset the new_top value for the space.
895 _space_info[id].set_new_top(space->bottom());
896 } else if (live > 0) {
897 // Attempt to fit part of the source space into the target space.
898 HeapWord* next_src_addr = nullptr;
899 bool done = _summary_data.summarize(_space_info[id].split_info(),
900 space->bottom(), space->top(),
901 &next_src_addr,
902 *new_top_addr, dst_space_end,
903 new_top_addr);
904 assert(!done, "space should not fit into old gen");
905 assert(next_src_addr != nullptr, "sanity");
906
907 // The source space becomes the new target, so the remainder is compacted
908 // within the space itself.
909 dst_space_id = SpaceId(id);
910 dst_space_end = space->end();
911 new_top_addr = _space_info[id].new_top_addr();
912 done = _summary_data.summarize(_space_info[id].split_info(),
913 next_src_addr, space->top(),
914 nullptr,
915 space->bottom(), dst_space_end,
916 new_top_addr);
917 assert(done, "space must fit when compacted into itself");
918 assert(*new_top_addr <= space->top(), "usage should not grow");
919 }
920 }
921 }
922
923 void PSParallelCompact::report_object_count_after_gc() {
924 GCTraceTime(Debug, gc, phases) tm("Report Object Count", &_gc_timer);
925 // The heap is compacted, all objects are iterable. However there may be
926 // filler objects in the heap which we should ignore.
927 class SkipFillerObjectClosure : public BoolObjectClosure {
928 public:
929 bool do_object_b(oop obj) override { return !CollectedHeap::is_filler_object(obj); }
930 } cl;
931 _gc_tracer.report_object_count_after_gc(&cl, &ParallelScavengeHeap::heap()->workers());
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 FullGCForwarding::begin();
997
998 forward_to_new_addr();
999
1000 adjust_pointers();
1001
1002 compact();
1003
1004 FullGCForwarding::end();
1005
1006 ParCompactionManager::_preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
1007
1008 ParCompactionManager::verify_all_region_stack_empty();
1009
1010 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1011 // done before resizing.
1012 post_compact();
1013
1014 size_policy->major_collection_end();
1015
1016 size_policy->sample_old_gen_used_bytes(MAX2(pre_gc_values.old_gen_used(), old_gen->used_in_bytes()));
1017
1018 if (UseAdaptiveSizePolicy) {
1019 heap->resize_after_full_gc();
1020 }
1021
1022 heap->resize_all_tlabs();
1023
1024 // Resize the metaspace capacity after a collection
1025 MetaspaceGC::compute_new_size();
1026
1027 if (log_is_enabled(Debug, gc, heap, exit)) {
1028 accumulated_time()->stop();
1029 }
1030
1031 heap->print_heap_change(pre_gc_values);
1032
1033 report_object_count_after_gc();
1034
1035 // Track memory usage and detect low memory
1036 MemoryService::track_memory_usage();
1037 heap->update_counters();
1038
1039 heap->post_full_gc_dump(&_gc_timer);
1040
1041 size_policy->record_gc_pause_end_instant();
1042 }
1043
1044 heap->gc_epilogue(true);
1045
1046 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1047 Universe::verify("After GC");
1048 }
1049
1050 heap->print_after_gc();
1051 heap->trace_heap_after_gc(&_gc_tracer);
1052
1053 _gc_timer.register_gc_end();
1054
1055 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1056 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1057
1058 return true;
1059 }
1060
1061 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1062 ParCompactionManager* _cm;
1063
1064 public:
1065 PCAddThreadRootsMarkingTaskClosure(ParCompactionManager* cm) : _cm(cm) { }
1066 void do_thread(Thread* thread) {
1067 ResourceMark rm;
1068
1069 MarkingNMethodClosure mark_and_push_in_blobs(&_cm->_mark_and_push_closure);
1070
1071 thread->oops_do(&_cm->_mark_and_push_closure, &mark_and_push_in_blobs);
1072
1073 // Do the real work
1074 _cm->follow_marking_stacks();
1075 }
1076 };
1077
1078 void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
1079 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1080
1081 ParCompactionManager* cm =
1082 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1083
1084 do {
1085 ScannerTask task;
1086 if (ParCompactionManager::steal(worker_id, task)) {
1087 cm->follow_contents(task, true);
1088 }
1089 cm->follow_marking_stacks();
1090 } while (!terminator.offer_termination());
1091 }
1092
1093 class MarkFromRootsTask : public WorkerTask {
1094 NMethodMarkingScope _nmethod_marking_scope;
1095 ThreadsClaimTokenScope _threads_claim_token_scope;
1096 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
1097 TaskTerminator _terminator;
1098 uint _active_workers;
1099
1100 public:
1101 MarkFromRootsTask(uint active_workers) :
1102 WorkerTask("MarkFromRootsTask"),
1103 _nmethod_marking_scope(),
1104 _threads_claim_token_scope(),
1105 _terminator(active_workers, ParCompactionManager::marking_stacks()),
1106 _active_workers(active_workers) {}
1107
1108 virtual void work(uint worker_id) {
1109 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1110 cm->create_marking_stats_cache();
1111 {
1112 CLDToOopClosure cld_closure(&cm->_mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
1113 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
1114
1115 // Do the real work
1116 cm->follow_marking_stacks();
1117 }
1118
1119 {
1120 PCAddThreadRootsMarkingTaskClosure closure(cm);
1121 Threads::possibly_parallel_threads_do(_active_workers > 1 /* is_par */, &closure);
1122 }
1123
1124 // Mark from OopStorages
1125 {
1126 _oop_storage_set_par_state.oops_do(&cm->_mark_and_push_closure);
1127 // Do the real work
1128 cm->follow_marking_stacks();
1129 }
1130
1131 if (_active_workers > 1) {
1132 steal_marking_work(_terminator, worker_id);
1133 }
1134 }
1135 };
1136
1137 class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
1138 TaskTerminator _terminator;
1139
1140 public:
1141 ParallelCompactRefProcProxyTask(uint max_workers)
1142 : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers),
1143 _terminator(_max_workers, ParCompactionManager::marking_stacks()) {}
1144
1145 void work(uint worker_id) override {
1146 assert(worker_id < _max_workers, "sanity");
1147 ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
1148 BarrierEnqueueDiscoveredFieldClosure enqueue;
1149 ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
1150 _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &cm->_mark_and_push_closure, &enqueue, &complete_gc);
1151 }
1152
1153 void prepare_run_task_hook() override {
1154 _terminator.reset_for_reuse(_queue_count);
1155 }
1156 };
1157
1158 static void flush_marking_stats_cache(const uint num_workers) {
1159 for (uint i = 0; i < num_workers; ++i) {
1160 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(i);
1161 cm->flush_and_destroy_marking_stats_cache();
1162 }
1163 }
1164
1165 class PSParallelCleaningTask : public WorkerTask {
1166 bool _unloading_occurred;
1167 CodeCacheUnloadingTask _code_cache_task;
1168 // Prune dead klasses from subklass/sibling/implementor lists.
1169 KlassCleaningTask _klass_cleaning_task;
1170
1171 public:
1172 PSParallelCleaningTask(bool unloading_occurred) :
1173 WorkerTask("PS Parallel Cleaning"),
1174 _unloading_occurred(unloading_occurred),
1175 _code_cache_task(unloading_occurred),
1176 _klass_cleaning_task() {}
1177
1178 void work(uint worker_id) {
1179 #if INCLUDE_JVMCI
1180 if (EnableJVMCI && worker_id == 0) {
1181 // Serial work; only first worker.
1182 // Clean JVMCI metadata handles.
1183 JVMCI::do_unloading(_unloading_occurred);
1184 }
1185 #endif
1186
1187 // Do first pass of code cache cleaning.
1188 _code_cache_task.work(worker_id);
1189
1190 // Clean all klasses that were not unloaded.
1191 // The weak metadata in klass doesn't need to be
1192 // processed if there was no unloading.
1193 if (_unloading_occurred) {
1194 _klass_cleaning_task.work();
1195 }
1196 }
1197 };
1198
1199 void PSParallelCompact::marking_phase(ParallelOldTracer *gc_tracer) {
1200 // Recursively traverse all live objects and mark them
1201 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
1202
1203 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1204
1205 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
1206 {
1207 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
1208
1209 MarkFromRootsTask task(active_gc_threads);
1210 ParallelScavengeHeap::heap()->workers().run_task(&task);
1211 }
1212
1213 // Process reference objects found during marking
1214 {
1215 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
1216
1217 ReferenceProcessorStats stats;
1218 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
1219
1220 ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues());
1221 stats = ref_processor()->process_discovered_references(task, &ParallelScavengeHeap::heap()->workers(), pt);
1222
1223 gc_tracer->report_gc_reference_stats(stats);
1224 pt.print_all_references();
1225 }
1226
1227 {
1228 GCTraceTime(Debug, gc, phases) tm("Flush Marking Stats", &_gc_timer);
1229
1230 flush_marking_stats_cache(active_gc_threads);
1231 }
1232
1233 // This is the point where the entire marking should have completed.
1234 ParCompactionManager::verify_all_marking_stack_empty();
1235
1236 {
1237 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
1238 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(),
1239 is_alive_closure(),
1240 &do_nothing_cl,
1241 1);
1242 }
1243
1244 {
1245 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
1246
1247 ClassUnloadingContext ctx(active_gc_threads /* num_nmethod_unlink_workers */,
1248 false /* unregister_nmethods_during_purge */,
1249 false /* lock_nmethod_free_separately */);
1250
1251 {
1252 CodeCache::UnlinkingScope scope(is_alive_closure());
1253
1254 // Follow system dictionary roots and unload classes.
1255 bool unloading_occurred = SystemDictionary::do_unloading(&_gc_timer);
1256
1257 PSParallelCleaningTask task{unloading_occurred};
1258 ParallelScavengeHeap::heap()->workers().run_task(&task);
1259 }
1260
1261 {
1262 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
1263 // Release unloaded nmethod's memory.
1264 ctx.purge_nmethods();
1265 }
1266 {
1267 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", &_gc_timer);
1268 ParallelScavengeHeap::heap()->prune_unlinked_nmethods();
1269 }
1270 {
1271 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
1272 ctx.free_nmethods();
1273 }
1274 {
1275 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1276 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", gc_timer());
1277 ClassLoaderDataGraph::purge(true /* at_safepoint */);
1278 DEBUG_ONLY(MetaspaceUtils::verify();)
1279 }
1280 }
1281
1282 #if TASKQUEUE_STATS
1283 ParCompactionManager::print_and_reset_taskqueue_stats();
1284 #endif
1285 }
1286
1287 template<typename Func>
1288 void PSParallelCompact::adjust_in_space_helper(SpaceId id, Atomic<uint>* claim_counter, Func&& on_stripe) {
1289 MutableSpace* sp = PSParallelCompact::space(id);
1290 HeapWord* const bottom = sp->bottom();
1291 HeapWord* const top = sp->top();
1292 if (bottom == top) {
1293 return;
1294 }
1295
1296 const uint num_regions_per_stripe = 2;
1297 const size_t region_size = ParallelCompactData::RegionSize;
1298 const size_t stripe_size = num_regions_per_stripe * region_size;
1299
1300 while (true) {
1301 uint counter = claim_counter->fetch_then_add(num_regions_per_stripe);
1302 HeapWord* cur_stripe = bottom + counter * region_size;
1303 if (cur_stripe >= top) {
1304 break;
1305 }
1306 HeapWord* stripe_end = MIN2(cur_stripe + stripe_size, top);
1307 on_stripe(cur_stripe, stripe_end);
1308 }
1309 }
1310
1311 void PSParallelCompact::adjust_in_old_space(Atomic<uint>* claim_counter) {
1312 // Regions in old-space shouldn't be split.
1313 assert(!_space_info[old_space_id].split_info().is_valid(), "inv");
1314
1315 auto scan_obj_with_limit = [&] (HeapWord* obj_start, HeapWord* left, HeapWord* right) {
1316 assert(mark_bitmap()->is_marked(obj_start), "inv");
1317 oop obj = cast_to_oop(obj_start);
1318 return obj->oop_iterate_size(&pc_adjust_pointer_closure, MemRegion(left, right));
1319 };
1320
1321 adjust_in_space_helper(old_space_id, claim_counter, [&] (HeapWord* stripe_start, HeapWord* stripe_end) {
1322 assert(_summary_data.is_region_aligned(stripe_start), "inv");
1323 RegionData* cur_region = _summary_data.addr_to_region_ptr(stripe_start);
1324 HeapWord* obj_start;
1325 if (cur_region->partial_obj_size() != 0) {
1326 obj_start = cur_region->partial_obj_addr();
1327 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1328 } else {
1329 obj_start = stripe_start;
1330 }
1331
1332 while (obj_start < stripe_end) {
1333 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1334 if (obj_start >= stripe_end) {
1335 break;
1336 }
1337 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1338 }
1339 });
1340 }
1341
1342 void PSParallelCompact::adjust_in_young_space(SpaceId id, Atomic<uint>* claim_counter) {
1343 adjust_in_space_helper(id, claim_counter, [](HeapWord* stripe_start, HeapWord* stripe_end) {
1344 HeapWord* obj_start = stripe_start;
1345 while (obj_start < stripe_end) {
1346 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1347 if (obj_start >= stripe_end) {
1348 break;
1349 }
1350 oop obj = cast_to_oop(obj_start);
1351 obj_start += obj->oop_iterate_size(&pc_adjust_pointer_closure);
1352 }
1353 });
1354 }
1355
1356 void PSParallelCompact::adjust_pointers_in_spaces(uint worker_id, Atomic<uint>* claim_counters) {
1357 auto start_time = Ticks::now();
1358 adjust_in_old_space(&claim_counters[0]);
1359 for (uint id = eden_space_id; id < last_space_id; ++id) {
1360 adjust_in_young_space(SpaceId(id), &claim_counters[id]);
1361 }
1362 log_trace(gc, phases)("adjust_pointers_in_spaces worker %u: %.3f ms", worker_id, (Ticks::now() - start_time).seconds() * 1000);
1363 }
1364
1365 class PSAdjustTask final : public WorkerTask {
1366 ThreadsClaimTokenScope _threads_claim_token_scope;
1367 WeakProcessor::Task _weak_proc_task;
1368 OopStorageSetStrongParState<false, false> _oop_storage_iter;
1369 uint _nworkers;
1370 Atomic<bool> _code_cache_claimed;
1371 Atomic<uint> _claim_counters[PSParallelCompact::last_space_id];
1372
1373 bool try_claim_code_cache_task() {
1374 return _code_cache_claimed.load_relaxed() == false
1375 && _code_cache_claimed.compare_set(false, true);
1376 }
1377
1378 public:
1379 PSAdjustTask(uint nworkers) :
1380 WorkerTask("PSAdjust task"),
1381 _threads_claim_token_scope(),
1382 _weak_proc_task(nworkers),
1383 _oop_storage_iter(),
1384 _nworkers(nworkers),
1385 _code_cache_claimed(false) {
1386
1387 for (unsigned int i = PSParallelCompact::old_space_id; i < PSParallelCompact::last_space_id; ++i) {
1388 ::new (&_claim_counters[i]) Atomic<uint>{};
1389 }
1390 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
1391 }
1392
1393 void work(uint worker_id) {
1394 {
1395 // Pointers in heap.
1396 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1397 cm->preserved_marks()->adjust_during_full_gc();
1398
1399 PSParallelCompact::adjust_pointers_in_spaces(worker_id, _claim_counters);
1400 }
1401
1402 {
1403 // All (strong and weak) CLDs.
1404 CLDToOopClosure cld_closure(&pc_adjust_pointer_closure, ClassLoaderData::_claim_stw_fullgc_adjust);
1405 ClassLoaderDataGraph::cld_do(&cld_closure);
1406 }
1407
1408 {
1409 // Threads stack frames. No need to visit on-stack nmethods, because all
1410 // nmethods are visited in one go via CodeCache::nmethods_do.
1411 ResourceMark rm;
1412 Threads::possibly_parallel_oops_do(_nworkers > 1, &pc_adjust_pointer_closure, nullptr);
1413 if (try_claim_code_cache_task()) {
1414 NMethodToOopClosure adjust_code(&pc_adjust_pointer_closure, NMethodToOopClosure::FixRelocations);
1415 CodeCache::nmethods_do(&adjust_code);
1416 }
1417 }
1418
1419 {
1420 // VM internal strong and weak roots.
1421 _oop_storage_iter.oops_do(&pc_adjust_pointer_closure);
1422 AlwaysTrueClosure always_alive;
1423 _weak_proc_task.work(worker_id, &always_alive, &pc_adjust_pointer_closure);
1424 }
1425 }
1426 };
1427
1428 void PSParallelCompact::adjust_pointers() {
1429 // Adjust the pointers to reflect the new locations
1430 GCTraceTime(Info, gc, phases) tm("Adjust Pointers", &_gc_timer);
1431 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1432 PSAdjustTask task(nworkers);
1433 ParallelScavengeHeap::heap()->workers().run_task(&task);
1434 }
1435
1436 // Split [start, end) evenly for a number of workers and return the
1437 // range for worker_id.
1438 static void split_regions_for_worker(size_t start, size_t end,
1439 uint worker_id, uint num_workers,
1440 size_t* worker_start, size_t* worker_end) {
1441 assert(start < end, "precondition");
1442 assert(num_workers > 0, "precondition");
1443 assert(worker_id < num_workers, "precondition");
1444
1445 size_t num_regions = end - start;
1446 size_t num_regions_per_worker = num_regions / num_workers;
1447 size_t remainder = num_regions % num_workers;
1448 // The first few workers will get one extra.
1449 *worker_start = start + worker_id * num_regions_per_worker
1450 + MIN2(checked_cast<size_t>(worker_id), remainder);
1451 *worker_end = *worker_start + num_regions_per_worker
1452 + (worker_id < remainder ? 1 : 0);
1453 }
1454
1455 void PSParallelCompact::forward_to_new_addr() {
1456 GCTraceTime(Info, gc, phases) tm("Forward", &_gc_timer);
1457 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1458
1459 struct ForwardTask final : public WorkerTask {
1460 uint _num_workers;
1461
1462 explicit ForwardTask(uint num_workers) :
1463 WorkerTask("PSForward task"),
1464 _num_workers(num_workers) {}
1465
1466 static void forward_objs_in_range(ParCompactionManager* cm,
1467 HeapWord* start,
1468 HeapWord* end,
1469 HeapWord* destination) {
1470 HeapWord* cur_addr = start;
1471 HeapWord* new_addr = destination;
1472
1473 while (cur_addr < end) {
1474 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, end);
1475 if (cur_addr >= end) {
1476 return;
1477 }
1478 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1479 oop obj = cast_to_oop(cur_addr);
1480 if (new_addr != cur_addr) {
1481 cm->preserved_marks()->push_if_necessary(obj, obj->mark());
1482 FullGCForwarding::forward_to(obj, cast_to_oop(new_addr));
1483 }
1484 size_t obj_size = obj->size();
1485 new_addr += obj_size;
1486 cur_addr += obj_size;
1487 }
1488 }
1489
1490 void work(uint worker_id) override {
1491 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1492 for (uint id = old_space_id; id < last_space_id; ++id) {
1493 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1494 HeapWord* dense_prefix_addr = dense_prefix(SpaceId(id));
1495 HeapWord* top = sp->top();
1496
1497 if (dense_prefix_addr == top) {
1498 // Empty space
1499 continue;
1500 }
1501
1502 const SplitInfo& split_info = _space_info[SpaceId(id)].split_info();
1503 size_t dense_prefix_region = _summary_data.addr_to_region_idx(dense_prefix_addr);
1504 size_t top_region = _summary_data.addr_to_region_idx(_summary_data.region_align_up(top));
1505 size_t start_region;
1506 size_t end_region;
1507 split_regions_for_worker(dense_prefix_region, top_region,
1508 worker_id, _num_workers,
1509 &start_region, &end_region);
1510 for (size_t cur_region = start_region; cur_region < end_region; ++cur_region) {
1511 RegionData* region_ptr = _summary_data.region(cur_region);
1512 size_t partial_obj_size = region_ptr->partial_obj_size();
1513
1514 if (partial_obj_size == ParallelCompactData::RegionSize) {
1515 // No obj-start
1516 continue;
1517 }
1518
1519 HeapWord* region_start = _summary_data.region_to_addr(cur_region);
1520 HeapWord* region_end = region_start + ParallelCompactData::RegionSize;
1521
1522 if (split_info.is_split(cur_region)) {
1523 // Part 1: will be relocated to space-1
1524 HeapWord* preceding_destination = split_info.preceding_destination();
1525 HeapWord* split_point = split_info.split_point();
1526 forward_objs_in_range(cm, region_start + partial_obj_size, split_point, preceding_destination + partial_obj_size);
1527
1528 // Part 2: will be relocated to space-2
1529 HeapWord* destination = region_ptr->destination();
1530 forward_objs_in_range(cm, split_point, region_end, destination);
1531 } else {
1532 HeapWord* destination = region_ptr->destination();
1533 forward_objs_in_range(cm, region_start + partial_obj_size, region_end, destination + partial_obj_size);
1534 }
1535 }
1536 }
1537 }
1538 } task(nworkers);
1539
1540 ParallelScavengeHeap::heap()->workers().run_task(&task);
1541 DEBUG_ONLY(verify_forward();)
1542 }
1543
1544 #ifdef ASSERT
1545 void PSParallelCompact::verify_forward() {
1546 HeapWord* const old_dense_prefix_addr = dense_prefix(SpaceId(old_space_id));
1547 // The destination addr for the first live obj after dense-prefix.
1548 HeapWord* bump_ptr = old_dense_prefix_addr
1549 + _summary_data.addr_to_region_ptr(old_dense_prefix_addr)->partial_obj_size();
1550 SpaceId bump_ptr_space = old_space_id;
1551
1552 for (uint id = old_space_id; id < last_space_id; ++id) {
1553 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1554 // Only verify objs after dense-prefix, because those before dense-prefix are not moved (forwarded).
1555 HeapWord* cur_addr = dense_prefix(SpaceId(id));
1556 HeapWord* top = sp->top();
1557
1558 while (cur_addr < top) {
1559 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, top);
1560 if (cur_addr >= top) {
1561 break;
1562 }
1563 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1564 assert(bump_ptr <= _space_info[bump_ptr_space].new_top(), "inv");
1565 // Move to the space containing cur_addr
1566 if (bump_ptr == _space_info[bump_ptr_space].new_top()) {
1567 bump_ptr = space(space_id(cur_addr))->bottom();
1568 bump_ptr_space = space_id(bump_ptr);
1569 }
1570 oop obj = cast_to_oop(cur_addr);
1571 if (cur_addr == bump_ptr) {
1572 assert(!FullGCForwarding::is_forwarded(obj), "inv");
1573 } else {
1574 assert(FullGCForwarding::forwardee(obj) == cast_to_oop(bump_ptr), "inv");
1575 }
1576 bump_ptr += obj->size();
1577 cur_addr += obj->size();
1578 }
1579 }
1580 }
1581 #endif
1582
1583 // Helper class to print 8 region numbers per line and then print the total at the end.
1584 class FillableRegionLogger : public StackObj {
1585 private:
1586 Log(gc, compaction) log;
1587 static const int LineLength = 8;
1588 size_t _regions[LineLength];
1589 int _next_index;
1590 bool _enabled;
1591 size_t _total_regions;
1592 public:
1593 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
1594 ~FillableRegionLogger() {
1595 log.trace("%zu initially fillable regions", _total_regions);
1596 }
1597
1598 void print_line() {
1599 if (!_enabled || _next_index == 0) {
1600 return;
1601 }
1602 FormatBuffer<> line("Fillable: ");
1603 for (int i = 0; i < _next_index; i++) {
1604 line.append(" %7zu", _regions[i]);
1605 }
1606 log.trace("%s", line.buffer());
1607 _next_index = 0;
1608 }
1609
1610 void handle(size_t region) {
1611 if (!_enabled) {
1612 return;
1613 }
1614 _regions[_next_index++] = region;
1615 if (_next_index == LineLength) {
1616 print_line();
1617 }
1618 _total_regions++;
1619 }
1620 };
1621
1622 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
1623 {
1624 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
1625
1626 // Find the threads that are active
1627 uint worker_id = 0;
1628
1629 // Find all regions that are available (can be filled immediately) and
1630 // distribute them to the thread stacks. The iteration is done in reverse
1631 // order (high to low) so the regions will be removed in ascending order.
1632
1633 const ParallelCompactData& sd = PSParallelCompact::summary_data();
1634
1635 // id + 1 is used to test termination so unsigned can
1636 // be used with an old_space_id == 0.
1637 FillableRegionLogger region_logger;
1638 for (unsigned int id = last_space_id - 1; id + 1 > old_space_id; --id) {
1639 SpaceInfo* const space_info = _space_info + id;
1640 HeapWord* const new_top = space_info->new_top();
1641
1642 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
1643 const size_t end_region =
1644 sd.addr_to_region_idx(sd.region_align_up(new_top));
1645
1646 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
1647 if (sd.region(cur)->claim_unsafe()) {
1648 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1649 bool result = sd.region(cur)->mark_normal();
1650 assert(result, "Must succeed at this point.");
1651 cm->region_stack()->push(cur);
1652 region_logger.handle(cur);
1653 // Assign regions to tasks in round-robin fashion.
1654 if (++worker_id == parallel_gc_threads) {
1655 worker_id = 0;
1656 }
1657 }
1658 }
1659 region_logger.print_line();
1660 }
1661 }
1662
1663 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
1664 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1665
1666 ParCompactionManager* cm =
1667 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1668
1669 // Drain the stacks that have been preloaded with regions
1670 // that are ready to fill.
1671
1672 cm->drain_region_stacks();
1673
1674 guarantee(cm->region_stack()->is_empty(), "Not empty");
1675
1676 size_t region_index = 0;
1677
1678 while (true) {
1679 if (ParCompactionManager::steal(worker_id, region_index)) {
1680 PSParallelCompact::fill_and_update_region(cm, region_index);
1681 cm->drain_region_stacks();
1682 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
1683 // Fill and update an unavailable region with the help of a shadow region
1684 PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
1685 cm->drain_region_stacks();
1686 } else {
1687 if (terminator->offer_termination()) {
1688 break;
1689 }
1690 // Go around again.
1691 }
1692 }
1693 }
1694
1695 class FillDensePrefixAndCompactionTask: public WorkerTask {
1696 TaskTerminator _terminator;
1697
1698 public:
1699 FillDensePrefixAndCompactionTask(uint active_workers) :
1700 WorkerTask("FillDensePrefixAndCompactionTask"),
1701 _terminator(active_workers, ParCompactionManager::region_task_queues()) {
1702 }
1703
1704 virtual void work(uint worker_id) {
1705 if (worker_id == 0) {
1706 auto start = Ticks::now();
1707 PSParallelCompact::fill_dead_objs_in_dense_prefix();
1708 log_trace(gc, phases)("Fill dense prefix by worker 0: %.3f ms", (Ticks::now() - start).seconds() * 1000);
1709 }
1710 compaction_with_stealing_work(&_terminator, worker_id);
1711 }
1712 };
1713
1714 void PSParallelCompact::fill_range_in_dense_prefix(HeapWord* start, HeapWord* end) {
1715 #ifdef ASSERT
1716 {
1717 assert(start < end, "precondition");
1718 assert(mark_bitmap()->find_obj_beg(start, end) == end, "precondition");
1719 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1720 if (start != bottom) {
1721 // The preceding live obj.
1722 HeapWord* obj_start = mark_bitmap()->find_obj_beg_reverse(bottom, start);
1723 HeapWord* obj_end = obj_start + cast_to_oop(obj_start)->size();
1724 assert(obj_end == start, "precondition");
1725 }
1726 }
1727 #endif
1728
1729 CollectedHeap::fill_with_objects(start, pointer_delta(end, start));
1730 HeapWord* addr = start;
1731 do {
1732 size_t size = cast_to_oop(addr)->size();
1733 start_array(old_space_id)->update_for_block(addr, addr + size);
1734 addr += size;
1735 } while (addr < end);
1736 }
1737
1738 void PSParallelCompact::fill_dead_objs_in_dense_prefix() {
1739 ParMarkBitMap* bitmap = mark_bitmap();
1740
1741 HeapWord* const bottom = _space_info[old_space_id].space()->bottom();
1742 HeapWord* const prefix_end = dense_prefix(old_space_id);
1743
1744 const size_t region_size = ParallelCompactData::RegionSize;
1745
1746 // Fill dead space in [start_addr, end_addr)
1747 HeapWord* const start_addr = bottom;
1748 HeapWord* const end_addr = prefix_end;
1749
1750 for (HeapWord* cur_addr = start_addr; cur_addr < end_addr; /* empty */) {
1751 RegionData* cur_region_ptr = _summary_data.addr_to_region_ptr(cur_addr);
1752 if (cur_region_ptr->data_size() == region_size) {
1753 // Full; no dead space. Next region.
1754 if (_summary_data.is_region_aligned(cur_addr)) {
1755 cur_addr += region_size;
1756 } else {
1757 cur_addr = _summary_data.region_align_up(cur_addr);
1758 }
1759 continue;
1760 }
1761
1762 // Fill dead space inside cur_region.
1763 if (_summary_data.is_region_aligned(cur_addr)) {
1764 cur_addr += cur_region_ptr->partial_obj_size();
1765 }
1766
1767 HeapWord* region_end_addr = _summary_data.region_align_up(cur_addr + 1);
1768 assert(region_end_addr <= end_addr, "inv");
1769 while (cur_addr < region_end_addr) {
1770 // Use end_addr to allow filler-obj to cross region boundary.
1771 HeapWord* live_start = bitmap->find_obj_beg(cur_addr, end_addr);
1772 if (cur_addr != live_start) {
1773 // Found dead space [cur_addr, live_start).
1774 fill_range_in_dense_prefix(cur_addr, live_start);
1775 }
1776 if (live_start >= region_end_addr) {
1777 cur_addr = live_start;
1778 break;
1779 }
1780 assert(bitmap->is_marked(live_start), "inv");
1781 cur_addr = live_start + cast_to_oop(live_start)->size();
1782 }
1783 }
1784 }
1785
1786 void PSParallelCompact::compact() {
1787 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
1788
1789 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1790
1791 initialize_shadow_regions(active_gc_threads);
1792 prepare_region_draining_tasks(active_gc_threads);
1793
1794 {
1795 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
1796
1797 FillDensePrefixAndCompactionTask task(active_gc_threads);
1798 ParallelScavengeHeap::heap()->workers().run_task(&task);
1799
1800 #ifdef ASSERT
1801 verify_filler_in_dense_prefix();
1802
1803 // Verify that all regions have been processed.
1804 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1805 verify_complete(SpaceId(id));
1806 }
1807 #endif
1808 }
1809 }
1810
1811 #ifdef ASSERT
1812 void PSParallelCompact::verify_filler_in_dense_prefix() {
1813 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1814 HeapWord* dense_prefix_end = dense_prefix(old_space_id);
1815
1816 const size_t region_size = ParallelCompactData::RegionSize;
1817
1818 for (HeapWord* cur_addr = bottom; cur_addr < dense_prefix_end; /* empty */) {
1819 RegionData* cur_region_ptr = _summary_data.addr_to_region_ptr(cur_addr);
1820 if (cur_region_ptr->data_size() == region_size) {
1821 // Full; no dead space. Next region.
1822 if (_summary_data.is_region_aligned(cur_addr)) {
1823 cur_addr += region_size;
1824 } else {
1825 cur_addr = _summary_data.region_align_up(cur_addr);
1826 }
1827 continue;
1828 }
1829
1830 // This region contains filler objs.
1831 if (_summary_data.is_region_aligned(cur_addr)) {
1832 cur_addr += cur_region_ptr->partial_obj_size();
1833 }
1834
1835 HeapWord* region_end_addr = _summary_data.region_align_up(cur_addr + 1);
1836 assert(region_end_addr <= dense_prefix_end, "inv");
1837
1838 while (cur_addr < region_end_addr) {
1839 oop obj = cast_to_oop(cur_addr);
1840 oopDesc::verify(obj);
1841 if (!mark_bitmap()->is_marked(cur_addr)) {
1842 assert(CollectedHeap::is_filler_object(cast_to_oop(cur_addr)), "inv");
1843 }
1844 cur_addr += obj->size();
1845 }
1846 }
1847 }
1848
1849 void PSParallelCompact::verify_complete(SpaceId space_id) {
1850 // All Regions served as compaction targets, from dense_prefix() to
1851 // new_top(), should be marked as filled and all Regions between new_top()
1852 // and top() should be available (i.e., should have been emptied).
1853 ParallelCompactData& sd = summary_data();
1854 SpaceInfo si = _space_info[space_id];
1855 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
1856 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
1857 const size_t beg_region = sd.addr_to_region_idx(si.dense_prefix());
1858 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
1859 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
1860
1861 size_t cur_region;
1862 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
1863 const RegionData* const c = sd.region(cur_region);
1864 assert(c->completed(), "region %zu not filled: destination_count=%u",
1865 cur_region, c->destination_count());
1866 }
1867
1868 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
1869 const RegionData* const c = sd.region(cur_region);
1870 assert(c->available(), "region %zu not empty: destination_count=%u",
1871 cur_region, c->destination_count());
1872 }
1873 }
1874 #endif // #ifdef ASSERT
1875
1876 // Return the SpaceId for the space containing addr. If addr is not in the
1877 // heap, last_space_id is returned. In debug mode it expects the address to be
1878 // in the heap and asserts such.
1879 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
1880 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
1881
1882 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1883 if (_space_info[id].space()->contains(addr)) {
1884 return SpaceId(id);
1885 }
1886 }
1887
1888 assert(false, "no space contains the addr");
1889 return last_space_id;
1890 }
1891
1892 // Skip over count live words starting from beg, and return the address of the
1893 // next live word. Callers must also ensure that there are enough live words in
1894 // the range [beg, end) to skip.
1895 HeapWord* PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
1896 {
1897 ParMarkBitMap* m = mark_bitmap();
1898 HeapWord* cur_addr = beg;
1899 while (true) {
1900 cur_addr = m->find_obj_beg(cur_addr, end);
1901 assert(cur_addr < end, "inv");
1902 size_t obj_size = cast_to_oop(cur_addr)->size();
1903 // Strictly greater-than
1904 if (obj_size > count) {
1905 return cur_addr + count;
1906 }
1907 count -= obj_size;
1908 cur_addr += obj_size;
1909 }
1910 }
1911
1912 // On starting to fill a destination region (dest-region), we need to know the
1913 // location of the word that will be at the start of the dest-region after
1914 // compaction. A dest-region can have one or more source regions, but only the
1915 // first source-region contains this location. This location is retrieved by
1916 // calling `first_src_addr` on a dest-region.
1917 // Conversely, a source-region has a dest-region which holds the destination of
1918 // the first live word on this source-region, based on which the destination
1919 // for the rest of live words can be derived.
1920 //
1921 // Note:
1922 // There is some complication due to space-boundary-fragmentation (an obj can't
1923 // cross space-boundary) -- a source-region may be split and behave like two
1924 // distinct regions with their own dest-region, as depicted below.
1925 //
1926 // source-region: region-n
1927 //
1928 // **********************
1929 // | A|A~~~~B|B |
1930 // **********************
1931 // n-1 n n+1
1932 //
1933 // AA, BB denote two live objs. ~~~~ denotes unknown number of live objs.
1934 //
1935 // Assuming the dest-region for region-n is the final region before
1936 // old-space-end and its first-live-word is the middle of AA, the heap content
1937 // will look like the following after compaction:
1938 //
1939 // ************** *************
1940 // A|A~~~~ | |BB |
1941 // ************** *************
1942 // ^ ^
1943 // | old-space-end | eden-space-start
1944 //
1945 // Therefore, in this example, region-n will have two dest-regions:
1946 // 1. the final region in old-space
1947 // 2. the first region in eden-space.
1948 // To handle this special case, we introduce the concept of split-region, whose
1949 // contents are relocated to two spaces. `SplitInfo` captures all necessary
1950 // info about the split, the first part, spliting-point, and the second part.
1951 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
1952 SpaceId src_space_id,
1953 size_t src_region_idx)
1954 {
1955 const size_t RegionSize = ParallelCompactData::RegionSize;
1956 const ParallelCompactData& sd = summary_data();
1957 assert(sd.is_region_aligned(dest_addr), "precondition");
1958
1959 const RegionData* const src_region_ptr = sd.region(src_region_idx);
1960 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
1961
1962 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
1963 HeapWord* const src_region_destination = src_region_ptr->destination();
1964
1965 HeapWord* const region_start = sd.region_to_addr(src_region_idx);
1966 HeapWord* const region_end = sd.region_to_addr(src_region_idx) + RegionSize;
1967
1968 // Identify the actual destination for the first live words on this region,
1969 // taking split-region into account.
1970 HeapWord* region_start_destination;
1971 const SplitInfo& split_info = _space_info[src_space_id].split_info();
1972 if (split_info.is_split(src_region_idx)) {
1973 // The second part of this split region; use the recorded split point.
1974 if (dest_addr == src_region_destination) {
1975 return split_info.split_point();
1976 }
1977 region_start_destination = split_info.preceding_destination();
1978 } else {
1979 region_start_destination = src_region_destination;
1980 }
1981
1982 // Calculate the offset to be skipped
1983 size_t words_to_skip = pointer_delta(dest_addr, region_start_destination);
1984
1985 HeapWord* result;
1986 if (partial_obj_size > words_to_skip) {
1987 result = region_start + words_to_skip;
1988 } else {
1989 words_to_skip -= partial_obj_size;
1990 result = skip_live_words(region_start + partial_obj_size, region_end, words_to_skip);
1991 }
1992
1993 if (split_info.is_split(src_region_idx)) {
1994 assert(result < split_info.split_point(), "postcondition");
1995 } else {
1996 assert(result < region_end, "postcondition");
1997 }
1998
1999 return result;
2000 }
2001
2002 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2003 SpaceId src_space_id,
2004 size_t beg_region,
2005 HeapWord* end_addr)
2006 {
2007 ParallelCompactData& sd = summary_data();
2008
2009 #ifdef ASSERT
2010 MutableSpace* const src_space = _space_info[src_space_id].space();
2011 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2012 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2013 "src_space_id does not match beg_addr");
2014 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2015 "src_space_id does not match end_addr");
2016 #endif // #ifdef ASSERT
2017
2018 RegionData* const beg = sd.region(beg_region);
2019 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2020
2021 // Regions up to new_top() are enqueued if they become available.
2022 HeapWord* const new_top = _space_info[src_space_id].new_top();
2023 RegionData* const enqueue_end =
2024 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2025
2026 for (RegionData* cur = beg; cur < end; ++cur) {
2027 assert(cur->data_size() > 0, "region must have live data");
2028 cur->decrement_destination_count();
2029 if (cur < enqueue_end && cur->available() && cur->claim()) {
2030 if (cur->mark_normal()) {
2031 cm->push_region(sd.region(cur));
2032 } else if (cur->mark_copied()) {
2033 // Try to copy the content of the shadow region back to its corresponding
2034 // heap region if the shadow region is filled. Otherwise, the GC thread
2035 // fills the shadow region will copy the data back (see
2036 // MoveAndUpdateShadowClosure::complete_region).
2037 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2038 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2039 cur->set_completed();
2040 }
2041 }
2042 }
2043 }
2044
2045 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2046 SpaceId& src_space_id,
2047 HeapWord*& src_space_top,
2048 HeapWord* end_addr)
2049 {
2050 ParallelCompactData& sd = PSParallelCompact::summary_data();
2051
2052 size_t src_region_idx = 0;
2053
2054 // Skip empty regions (if any) up to the top of the space.
2055 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2056 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2057 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2058 const RegionData* const top_region_ptr = sd.addr_to_region_ptr(top_aligned_up);
2059
2060 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2061 ++src_region_ptr;
2062 }
2063
2064 if (src_region_ptr < top_region_ptr) {
2065 // Found the first non-empty region in the same space.
2066 src_region_idx = sd.region(src_region_ptr);
2067 closure.set_source(sd.region_to_addr(src_region_idx));
2068 return src_region_idx;
2069 }
2070
2071 // Switch to a new source space and find the first non-empty region.
2072 uint space_id = src_space_id + 1;
2073 assert(space_id < last_space_id, "not enough spaces");
2074
2075 for (/* empty */; space_id < last_space_id; ++space_id) {
2076 HeapWord* bottom = _space_info[space_id].space()->bottom();
2077 HeapWord* top = _space_info[space_id].space()->top();
2078 // Skip empty space
2079 if (bottom == top) {
2080 continue;
2081 }
2082
2083 // Identify the first region that contains live words in this space
2084 size_t cur_region = sd.addr_to_region_idx(bottom);
2085 size_t end_region = sd.addr_to_region_idx(sd.region_align_up(top));
2086
2087 for (/* empty */ ; cur_region < end_region; ++cur_region) {
2088 RegionData* cur = sd.region(cur_region);
2089 if (cur->live_obj_size() > 0) {
2090 HeapWord* region_start_addr = sd.region_to_addr(cur_region);
2091
2092 src_space_id = SpaceId(space_id);
2093 src_space_top = top;
2094 closure.set_source(region_start_addr);
2095 return cur_region;
2096 }
2097 }
2098 }
2099
2100 ShouldNotReachHere();
2101 }
2102
2103 HeapWord* PSParallelCompact::partial_obj_end(HeapWord* region_start_addr) {
2104 ParallelCompactData& sd = summary_data();
2105 assert(sd.is_region_aligned(region_start_addr), "precondition");
2106
2107 // Use per-region partial_obj_size to locate the end of the obj, that extends
2108 // to region_start_addr.
2109 size_t start_region_idx = sd.addr_to_region_idx(region_start_addr);
2110 size_t end_region_idx = sd.region_count();
2111 size_t accumulated_size = 0;
2112 for (size_t region_idx = start_region_idx; region_idx < end_region_idx; ++region_idx) {
2113 size_t cur_partial_obj_size = sd.region(region_idx)->partial_obj_size();
2114 accumulated_size += cur_partial_obj_size;
2115 if (cur_partial_obj_size != ParallelCompactData::RegionSize) {
2116 break;
2117 }
2118 }
2119 return region_start_addr + accumulated_size;
2120 }
2121
2122 // Use region_idx as the destination region, and evacuate all live objs on its
2123 // source regions to this destination region.
2124 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2125 {
2126 ParMarkBitMap* const bitmap = mark_bitmap();
2127 ParallelCompactData& sd = summary_data();
2128 RegionData* const region_ptr = sd.region(region_idx);
2129
2130 // Get the source region and related info.
2131 size_t src_region_idx = region_ptr->source_region();
2132 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2133 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2134 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2135
2136 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2137
2138 // Adjust src_region_idx to prepare for decrementing destination counts (the
2139 // destination count is not decremented when a region is copied to itself).
2140 if (src_region_idx == region_idx) {
2141 src_region_idx += 1;
2142 }
2143
2144 // source-region:
2145 //
2146 // **********
2147 // | ~~~ |
2148 // **********
2149 // ^
2150 // |-- closure.source() / first_src_addr
2151 //
2152 //
2153 // ~~~ : live words
2154 //
2155 // destination-region:
2156 //
2157 // **********
2158 // | |
2159 // **********
2160 // ^
2161 // |-- region-start
2162 if (bitmap->is_unmarked(closure.source())) {
2163 // An object overflows the previous destination region, so this
2164 // destination region should copy the remainder of the object or as much as
2165 // will fit.
2166 HeapWord* const old_src_addr = closure.source();
2167 {
2168 HeapWord* region_start = sd.region_align_down(closure.source());
2169 HeapWord* obj_start = bitmap->find_obj_beg_reverse(region_start, closure.source());
2170 HeapWord* obj_end;
2171 if (obj_start != closure.source()) {
2172 assert(bitmap->is_marked(obj_start), "inv");
2173 // Found the actual obj-start, try to find the obj-end using either
2174 // size() if this obj is completely contained in the current region.
2175 HeapWord* next_region_start = region_start + ParallelCompactData::RegionSize;
2176 HeapWord* partial_obj_start = (next_region_start >= src_space_top)
2177 ? nullptr
2178 : sd.addr_to_region_ptr(next_region_start)->partial_obj_addr();
2179 // This obj extends to next region iff partial_obj_addr of the *next*
2180 // region is the same as obj-start.
2181 if (partial_obj_start == obj_start) {
2182 // This obj extends to next region.
2183 obj_end = partial_obj_end(next_region_start);
2184 } else {
2185 // Completely contained in this region; safe to use size().
2186 obj_end = obj_start + cast_to_oop(obj_start)->size();
2187 }
2188 } else {
2189 // This obj extends to current region.
2190 obj_end = partial_obj_end(region_start);
2191 }
2192 size_t partial_obj_size = pointer_delta(obj_end, closure.source());
2193 closure.copy_partial_obj(partial_obj_size);
2194 }
2195
2196 if (closure.is_full()) {
2197 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2198 closure.complete_region(dest_addr, region_ptr);
2199 return;
2200 }
2201
2202 // Finished copying without using up the current destination-region
2203 HeapWord* const end_addr = sd.region_align_down(closure.source());
2204 if (sd.region_align_down(old_src_addr) != end_addr) {
2205 assert(sd.region_align_up(old_src_addr) == end_addr, "only one region");
2206 // The partial object was copied from more than one source region.
2207 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2208
2209 // Move to the next source region, possibly switching spaces as well. All
2210 // args except end_addr may be modified.
2211 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2212 }
2213 }
2214
2215 // Handle the rest obj-by-obj, where we know obj-start.
2216 do {
2217 HeapWord* cur_addr = closure.source();
2218 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2219 src_space_top);
2220 // To handle the case where the final obj in source region extends to next region.
2221 HeapWord* final_obj_start = (end_addr == src_space_top)
2222 ? nullptr
2223 : sd.addr_to_region_ptr(end_addr)->partial_obj_addr();
2224 // Apply closure on objs inside [cur_addr, end_addr)
2225 do {
2226 cur_addr = bitmap->find_obj_beg(cur_addr, end_addr);
2227 if (cur_addr == end_addr) {
2228 break;
2229 }
2230 size_t obj_size;
2231 if (final_obj_start == cur_addr) {
2232 obj_size = pointer_delta(partial_obj_end(end_addr), cur_addr);
2233 } else {
2234 // This obj doesn't extend into next region; size() is safe to use.
2235 obj_size = cast_to_oop(cur_addr)->size();
2236 }
2237 closure.do_addr(cur_addr, obj_size);
2238 cur_addr += obj_size;
2239 } while (cur_addr < end_addr && !closure.is_full());
2240
2241 if (closure.is_full()) {
2242 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2243 closure.complete_region(dest_addr, region_ptr);
2244 return;
2245 }
2246
2247 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2248
2249 // Move to the next source region, possibly switching spaces as well. All
2250 // args except end_addr may be modified.
2251 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2252 } while (true);
2253 }
2254
2255 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
2256 {
2257 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2258 fill_region(cm, cl, region_idx);
2259 }
2260
2261 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
2262 {
2263 // Get a shadow region first
2264 ParallelCompactData& sd = summary_data();
2265 RegionData* const region_ptr = sd.region(region_idx);
2266 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
2267 // The InvalidShadow return value indicates the corresponding heap region is available,
2268 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
2269 // MoveAndUpdateShadowClosure to fill the acquired shadow region.
2270 if (shadow_region == ParCompactionManager::InvalidShadow) {
2271 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2272 region_ptr->shadow_to_normal();
2273 return fill_region(cm, cl, region_idx);
2274 } else {
2275 MoveAndUpdateShadowClosure cl(mark_bitmap(), region_idx, shadow_region);
2276 return fill_region(cm, cl, region_idx);
2277 }
2278 }
2279
2280 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
2281 {
2282 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
2283 }
2284
2285 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx)
2286 {
2287 size_t next = cm->next_shadow_region();
2288 ParallelCompactData& sd = summary_data();
2289 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
2290 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2291
2292 while (next < old_new_top) {
2293 if (sd.region(next)->mark_shadow()) {
2294 region_idx = next;
2295 return true;
2296 }
2297 next = cm->move_next_shadow_region_by(active_gc_threads);
2298 }
2299
2300 return false;
2301 }
2302
2303 // The shadow region is an optimization to address region dependencies in full GC. The basic
2304 // idea is making more regions available by temporally storing their live objects in empty
2305 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
2306 // GC threads need not wait destination regions to be available before processing sources.
2307 //
2308 // A typical workflow would be:
2309 // After draining its own stack and failing to steal from others, a GC worker would pick an
2310 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
2311 // the shadow region by copying live objects from source regions of the unavailable one. Once
2312 // the unavailable region becomes available, the data in the shadow region will be copied back.
2313 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
2314 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
2315 {
2316 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2317
2318 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2319 SpaceInfo* const space_info = _space_info + id;
2320 MutableSpace* const space = space_info->space();
2321
2322 const size_t beg_region =
2323 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
2324 const size_t end_region =
2325 sd.addr_to_region_idx(sd.region_align_down(space->end()));
2326
2327 for (size_t cur = beg_region; cur < end_region; ++cur) {
2328 ParCompactionManager::push_shadow_region(cur);
2329 }
2330 }
2331
2332 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
2333 for (uint i = 0; i < parallel_gc_threads; i++) {
2334 ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i);
2335 cm->set_next_shadow_region(beg_region + i);
2336 }
2337 }
2338
2339 void MoveAndUpdateClosure::copy_partial_obj(size_t partial_obj_size)
2340 {
2341 size_t words = MIN2(partial_obj_size, words_remaining());
2342
2343 // This test is necessary; if omitted, the pointer updates to a partial object
2344 // that crosses the dense prefix boundary could be overwritten.
2345 if (source() != copy_destination()) {
2346 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2347 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2348 }
2349 update_state(words);
2350 }
2351
2352 void MoveAndUpdateClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2353 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
2354 region_ptr->set_completed();
2355 }
2356
2357 void MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
2358 assert(destination() != nullptr, "sanity");
2359 _source = addr;
2360
2361 // The start_array must be updated even if the object is not moving.
2362 if (_start_array != nullptr) {
2363 _start_array->update_for_block(destination(), destination() + words);
2364 }
2365
2366 // Avoid overflow
2367 words = MIN2(words, words_remaining());
2368 assert(words > 0, "inv");
2369
2370 if (copy_destination() != source()) {
2371 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2372 assert(source() != destination(), "inv");
2373 assert(FullGCForwarding::is_forwarded(cast_to_oop(source())), "inv");
2374 assert(FullGCForwarding::forwardee(cast_to_oop(source())) == cast_to_oop(destination()), "inv");
2375 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2376 cast_to_oop(copy_destination())->reinit_mark();
2377 }
2378
2379 update_state(words);
2380 }
2381
2382 void MoveAndUpdateShadowClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2383 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
2384 // Record the shadow region index
2385 region_ptr->set_shadow_region(_shadow);
2386 // Mark the shadow region as filled to indicate the data is ready to be
2387 // copied back
2388 region_ptr->mark_filled();
2389 // Try to copy the content of the shadow region back to its corresponding
2390 // heap region if available; the GC thread that decreases the destination
2391 // count to zero will do the copying otherwise (see
2392 // PSParallelCompact::decrement_destination_counts).
2393 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
2394 region_ptr->set_completed();
2395 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
2396 ParCompactionManager::push_shadow_region_mt_safe(_shadow);
2397 }
2398 }