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 "compiler/oopMap.hpp"
32 #include "gc/parallel/objectStartArray.inline.hpp"
33 #include "gc/parallel/parallelArguments.hpp"
34 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
35 #include "gc/parallel/parMarkBitMap.inline.hpp"
36 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
37 #include "gc/parallel/psCompactionManager.inline.hpp"
38 #include "gc/parallel/psOldGen.hpp"
39 #include "gc/parallel/psParallelCompact.inline.hpp"
40 #include "gc/parallel/psPromotionManager.inline.hpp"
41 #include "gc/parallel/psRootType.hpp"
42 #include "gc/parallel/psScavenge.hpp"
43 #include "gc/parallel/psStringDedup.hpp"
44 #include "gc/parallel/psYoungGen.hpp"
45 #include "gc/shared/classUnloadingContext.hpp"
46 #include "gc/shared/fullGCForwarding.inline.hpp"
47 #include "gc/shared/gcCause.hpp"
48 #include "gc/shared/gcHeapSummary.hpp"
49 #include "gc/shared/gcId.hpp"
50 #include "gc/shared/gcLocker.hpp"
51 #include "gc/shared/gcTimer.hpp"
52 #include "gc/shared/gcTrace.hpp"
53 #include "gc/shared/gcTraceTime.inline.hpp"
54 #include "gc/shared/gcVMOperations.hpp"
55 #include "gc/shared/isGCActiveMark.hpp"
56 #include "gc/shared/oopStorage.inline.hpp"
57 #include "gc/shared/oopStorageSet.inline.hpp"
58 #include "gc/shared/oopStorageSetParState.inline.hpp"
59 #include "gc/shared/preservedMarks.inline.hpp"
60 #include "gc/shared/referencePolicy.hpp"
61 #include "gc/shared/referenceProcessor.hpp"
62 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
63 #include "gc/shared/spaceDecorator.hpp"
64 #include "gc/shared/strongRootsScope.hpp"
65 #include "gc/shared/taskTerminator.hpp"
66 #include "gc/shared/weakProcessor.inline.hpp"
67 #include "gc/shared/workerPolicy.hpp"
68 #include "gc/shared/workerThread.hpp"
69 #include "gc/shared/workerUtils.hpp"
70 #include "logging/log.hpp"
71 #include "memory/iterator.inline.hpp"
72 #include "memory/memoryReserver.hpp"
73 #include "memory/metaspaceUtils.hpp"
74 #include "memory/resourceArea.hpp"
75 #include "memory/universe.hpp"
76 #include "nmt/memTracker.hpp"
77 #include "oops/access.inline.hpp"
78 #include "oops/flatArrayKlass.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/atomic.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 void
302 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
303 {
304 assert(is_region_aligned(beg), "not RegionSize aligned");
305 assert(is_region_aligned(end), "not RegionSize aligned");
306
307 size_t cur_region = addr_to_region_idx(beg);
308 const size_t end_region = addr_to_region_idx(end);
309 HeapWord* addr = beg;
310 while (cur_region < end_region) {
311 _region_data[cur_region].set_destination(addr);
312 _region_data[cur_region].set_destination_count(0);
313 _region_data[cur_region].set_source_region(cur_region);
314
315 // Update live_obj_size so the region appears completely full.
316 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
317 _region_data[cur_region].set_live_obj_size(live_size);
318
319 ++cur_region;
320 addr += RegionSize;
321 }
322 }
323
324 // The total live words on src_region would overflow the target space, so find
325 // the overflowing object and record the split point. The invariant is that an
326 // obj should not cross space boundary.
327 HeapWord* ParallelCompactData::summarize_split_space(size_t src_region,
328 SplitInfo& split_info,
329 HeapWord* const destination,
330 HeapWord* const target_end,
331 HeapWord** target_next) {
332 assert(destination <= target_end, "sanity");
333 assert(destination + _region_data[src_region].data_size() > target_end,
334 "region should not fit into target space");
335 assert(is_region_aligned(target_end), "sanity");
336
337 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
338
339 if (destination + partial_obj_size > target_end) {
340 assert(partial_obj_size > 0, "inv");
341 // The overflowing obj is from a previous region.
342 //
343 // source-regions:
344 //
345 // ***************
346 // | A|AA |
347 // ***************
348 // ^
349 // | split-point
350 //
351 // dest-region:
352 //
353 // ********
354 // |~~~~A |
355 // ********
356 // ^^
357 // || target-space-end
358 // |
359 // | destination
360 //
361 // AAA would overflow target-space.
362 //
363 HeapWord* overflowing_obj = _region_data[src_region].partial_obj_addr();
364 size_t split_region = addr_to_region_idx(overflowing_obj);
365
366 // The number of live words before the overflowing object on this split region
367 size_t preceding_live_words;
368 if (is_region_aligned(overflowing_obj)) {
369 preceding_live_words = 0;
370 } else {
371 // Words accounted by the overflowing object on the split region
372 size_t overflowing_size = pointer_delta(region_align_up(overflowing_obj), overflowing_obj);
373 preceding_live_words = region(split_region)->data_size() - overflowing_size;
374 }
375
376 split_info.record(split_region, overflowing_obj, preceding_live_words);
377
378 // The [overflowing_obj, src_region_start) part has been accounted for, so
379 // must move back the new_top, now that this overflowing obj is deferred.
380 HeapWord* new_top = destination - pointer_delta(region_to_addr(src_region), overflowing_obj);
381
382 // If the overflowing obj was relocated to its original destination,
383 // those destination regions would have their source_region set. Now that
384 // this overflowing obj is relocated somewhere else, reset the
385 // source_region.
386 {
387 size_t range_start = addr_to_region_idx(region_align_up(new_top));
388 size_t range_end = addr_to_region_idx(region_align_up(destination));
389 for (size_t i = range_start; i < range_end; ++i) {
390 region(i)->set_source_region(0);
391 }
392 }
393
394 // Update new top of target space
395 *target_next = new_top;
396
397 return overflowing_obj;
398 }
399
400 // Obj-iteration to locate the overflowing obj
401 HeapWord* region_start = region_to_addr(src_region);
402 HeapWord* region_end = region_start + RegionSize;
403 HeapWord* cur_addr = region_start + partial_obj_size;
404 size_t live_words = partial_obj_size;
405
406 while (true) {
407 assert(cur_addr < region_end, "inv");
408 cur_addr = PSParallelCompact::mark_bitmap()->find_obj_beg(cur_addr, region_end);
409 // There must be an overflowing obj in this region
410 assert(cur_addr < region_end, "inv");
411
412 oop obj = cast_to_oop(cur_addr);
413 size_t obj_size = obj->size();
414 if (destination + live_words + obj_size > target_end) {
415 // Found the overflowing obj
416 split_info.record(src_region, cur_addr, live_words);
417 *target_next = destination + live_words;
418 return cur_addr;
419 }
420
421 live_words += obj_size;
422 cur_addr += obj_size;
423 }
424 }
425
426 size_t ParallelCompactData::live_words_in_space(const MutableSpace* space,
427 HeapWord** full_region_prefix_end) {
428 size_t cur_region = addr_to_region_idx(space->bottom());
429 const size_t end_region = addr_to_region_idx(region_align_up(space->top()));
430 size_t live_words = 0;
431 if (full_region_prefix_end == nullptr) {
432 for (/* empty */; cur_region < end_region; ++cur_region) {
433 live_words += _region_data[cur_region].data_size();
434 }
435 } else {
436 bool first_set = false;
437 for (/* empty */; cur_region < end_region; ++cur_region) {
438 size_t live_words_in_region = _region_data[cur_region].data_size();
439 if (!first_set && live_words_in_region < RegionSize) {
440 *full_region_prefix_end = region_to_addr(cur_region);
441 first_set = true;
442 }
443 live_words += live_words_in_region;
444 }
445 if (!first_set) {
446 // All regions are full of live objs.
447 assert(is_region_aligned(space->top()), "inv");
448 *full_region_prefix_end = space->top();
449 }
450 assert(*full_region_prefix_end != nullptr, "postcondition");
451 assert(is_region_aligned(*full_region_prefix_end), "inv");
452 assert(*full_region_prefix_end >= space->bottom(), "in-range");
453 assert(*full_region_prefix_end <= space->top(), "in-range");
454 }
455 return live_words;
456 }
457
458 bool ParallelCompactData::summarize(SplitInfo& split_info,
459 HeapWord* source_beg, HeapWord* source_end,
460 HeapWord** source_next,
461 HeapWord* target_beg, HeapWord* target_end,
462 HeapWord** target_next)
463 {
464 HeapWord* const source_next_val = source_next == nullptr ? nullptr : *source_next;
465 log_develop_trace(gc, compaction)(
466 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
467 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
468 p2i(source_beg), p2i(source_end), p2i(source_next_val),
469 p2i(target_beg), p2i(target_end), p2i(*target_next));
470
471 size_t cur_region = addr_to_region_idx(source_beg);
472 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
473
474 HeapWord *dest_addr = target_beg;
475 for (/* empty */; cur_region < end_region; cur_region++) {
476 size_t words = _region_data[cur_region].data_size();
477
478 // Skip empty ones
479 if (words == 0) {
480 continue;
481 }
482
483 if (split_info.is_split(cur_region)) {
484 assert(words > split_info.preceding_live_words(), "inv");
485 words -= split_info.preceding_live_words();
486 }
487
488 _region_data[cur_region].set_destination(dest_addr);
489
490 // If cur_region does not fit entirely into the target space, find a point
491 // at which the source space can be 'split' so that part is copied to the
492 // target space and the rest is copied elsewhere.
493 if (dest_addr + words > target_end) {
494 assert(source_next != nullptr, "source_next is null when splitting");
495 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
496 target_end, target_next);
497 return false;
498 }
499
500 uint destination_count = split_info.is_split(cur_region)
501 ? split_info.preceding_destination_count()
502 : 0;
503
504 HeapWord* const last_addr = dest_addr + words - 1;
505 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
506 const size_t dest_region_2 = addr_to_region_idx(last_addr);
507
508 // Initially assume that the destination regions will be the same and
509 // adjust the value below if necessary. Under this assumption, if
510 // cur_region == dest_region_2, then cur_region will be compacted
511 // completely into itself.
512 destination_count += cur_region == dest_region_2 ? 0 : 1;
513 if (dest_region_1 != dest_region_2) {
514 // Destination regions differ; adjust destination_count.
515 destination_count += 1;
516 // Data from cur_region will be copied to the start of dest_region_2.
517 _region_data[dest_region_2].set_source_region(cur_region);
518 } else if (is_region_aligned(dest_addr)) {
519 // Data from cur_region will be copied to the start of the destination
520 // region.
521 _region_data[dest_region_1].set_source_region(cur_region);
522 }
523
524 _region_data[cur_region].set_destination_count(destination_count);
525 dest_addr += words;
526 }
527
528 *target_next = dest_addr;
529 return true;
530 }
531
532 #ifdef ASSERT
533 void ParallelCompactData::verify_clear() {
534 for (uint cur_idx = 0; cur_idx < region_count(); ++cur_idx) {
535 if (!region(cur_idx)->is_clear()) {
536 log_warning(gc)("Uncleared Region: %u", cur_idx);
537 region(cur_idx)->verify_clear();
538 }
539 }
540 }
541 #endif // #ifdef ASSERT
542
543 STWGCTimer PSParallelCompact::_gc_timer;
544 ParallelOldTracer PSParallelCompact::_gc_tracer;
545 elapsedTimer PSParallelCompact::_accumulated_time;
546 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
547 CollectorCounters* PSParallelCompact::_counters = nullptr;
548 ParMarkBitMap PSParallelCompact::_mark_bitmap;
549 ParallelCompactData PSParallelCompact::_summary_data;
550
551 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
552
553 class PCAdjustPointerClosure: public BasicOopIterateClosure {
554 template <typename T>
555 void do_oop_work(T* p) { PSParallelCompact::adjust_pointer(p); }
556
557 public:
558 virtual void do_oop(oop* p) { do_oop_work(p); }
559 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
560
561 virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
562 };
563
564 static PCAdjustPointerClosure pc_adjust_pointer_closure;
565
566 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
567
568 void PSParallelCompact::post_initialize() {
569 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
570 _span_based_discoverer.set_span(heap->reserved_region());
571 _ref_processor =
572 new ReferenceProcessor(&_span_based_discoverer,
573 ParallelGCThreads, // mt processing degree
574 ParallelGCThreads, // mt discovery degree
575 false, // concurrent_discovery
576 &_is_alive_closure); // non-header is alive closure
577
578 _counters = new CollectorCounters("Parallel full collection pauses", 1);
579
580 // Initialize static fields in ParCompactionManager.
581 ParCompactionManager::initialize(mark_bitmap());
582 }
583
584 bool PSParallelCompact::initialize_aux_data() {
585 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
586 MemRegion mr = heap->reserved_region();
587 assert(mr.byte_size() != 0, "heap should be reserved");
588
589 initialize_space_info();
590
591 if (!_mark_bitmap.initialize(mr)) {
592 vm_shutdown_during_initialization(
593 err_msg("Unable to allocate %zuKB bitmaps for parallel "
594 "garbage collection for the requested %zuKB heap.",
595 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
596 return false;
597 }
598
599 if (!_summary_data.initialize(mr)) {
600 vm_shutdown_during_initialization(
601 err_msg("Unable to allocate %zuKB card tables for parallel "
602 "garbage collection for the requested %zuKB heap.",
603 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
604 return false;
605 }
606
607 return true;
608 }
609
610 void PSParallelCompact::initialize_space_info()
611 {
612 memset(&_space_info, 0, sizeof(_space_info));
613
614 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
615 PSYoungGen* young_gen = heap->young_gen();
616
617 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
618 _space_info[eden_space_id].set_space(young_gen->eden_space());
619 _space_info[from_space_id].set_space(young_gen->from_space());
620 _space_info[to_space_id].set_space(young_gen->to_space());
621
622 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
623 }
624
625 void
626 PSParallelCompact::clear_data_covering_space(SpaceId id)
627 {
628 // At this point, top is the value before GC, new_top() is the value that will
629 // be set at the end of GC. The marking bitmap is cleared to top; nothing
630 // should be marked above top. The summary data is cleared to the larger of
631 // top & new_top.
632 MutableSpace* const space = _space_info[id].space();
633 HeapWord* const bot = space->bottom();
634 HeapWord* const top = space->top();
635 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
636
637 _mark_bitmap.clear_range(bot, top);
638
639 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
640 const size_t end_region =
641 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
642 _summary_data.clear_range(beg_region, end_region);
643
644 // Clear the data used to 'split' regions.
645 SplitInfo& split_info = _space_info[id].split_info();
646 if (split_info.is_valid()) {
647 split_info.clear();
648 }
649 DEBUG_ONLY(split_info.verify_clear();)
650 }
651
652 void PSParallelCompact::pre_compact()
653 {
654 // Update the from & to space pointers in space_info, since they are swapped
655 // at each young gen gc. Do the update unconditionally (even though a
656 // promotion failure does not swap spaces) because an unknown number of young
657 // collections will have swapped the spaces an unknown number of times.
658 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
659 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
660 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
661 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
662
663 heap->increment_total_collections(true);
664
665 CodeCache::on_gc_marking_cycle_start();
666
667 heap->print_before_gc();
668 heap->trace_heap_before_gc(&_gc_tracer);
669
670 // Fill in TLABs
671 heap->ensure_parsability(true); // retire TLABs
672
673 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
674 Universe::verify("Before GC");
675 }
676
677 DEBUG_ONLY(mark_bitmap()->verify_clear();)
678 DEBUG_ONLY(summary_data().verify_clear();)
679 }
680
681 void PSParallelCompact::post_compact()
682 {
683 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
684 ParCompactionManager::remove_all_shadow_regions();
685
686 CodeCache::on_gc_marking_cycle_finish();
687 CodeCache::arm_all_nmethods();
688
689 // Need to clear claim bits for the next full-gc (marking and adjust-pointers).
690 ClassLoaderDataGraph::clear_claimed_marks();
691
692 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
693 // Clear the marking bitmap, summary data and split info.
694 clear_data_covering_space(SpaceId(id));
695 {
696 MutableSpace* space = _space_info[id].space();
697 HeapWord* top = space->top();
698 HeapWord* new_top = _space_info[id].new_top();
699 if (ZapUnusedHeapArea && new_top < top) {
700 space->mangle_region(MemRegion(new_top, top));
701 }
702 // Update top(). Must be done after clearing the bitmap and summary data.
703 space->set_top(new_top);
704 }
705 }
706
707 #ifdef ASSERT
708 {
709 mark_bitmap()->verify_clear();
710 summary_data().verify_clear();
711 }
712 #endif
713
714 ParCompactionManager::flush_all_string_dedup_requests();
715
716 MutableSpace* const eden_space = _space_info[eden_space_id].space();
717 MutableSpace* const from_space = _space_info[from_space_id].space();
718 MutableSpace* const to_space = _space_info[to_space_id].space();
719
720 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
721 bool eden_empty = eden_space->is_empty();
722
723 // Update heap occupancy information which is used as input to the soft ref
724 // clearing policy at the next gc.
725 Universe::heap()->update_capacity_and_used_at_gc();
726
727 bool young_gen_empty = eden_empty && from_space->is_empty() &&
728 to_space->is_empty();
729
730 PSCardTable* ct = heap->card_table();
731 MemRegion old_mr = heap->old_gen()->committed();
732 if (young_gen_empty) {
733 ct->clear_MemRegion(old_mr);
734 } else {
735 ct->dirty_MemRegion(old_mr);
736 }
737
738 heap->prune_scavengable_nmethods();
739
740 #if COMPILER2_OR_JVMCI
741 DerivedPointerTable::update_pointers();
742 #endif
743
744 // Signal that we have completed a visit to all live objects.
745 Universe::heap()->record_whole_heap_examined_timestamp();
746 }
747
748 HeapWord* PSParallelCompact::compute_dense_prefix_for_old_space(MutableSpace* old_space,
749 HeapWord* full_region_prefix_end) {
750 const size_t region_size = ParallelCompactData::RegionSize;
751 const ParallelCompactData& sd = summary_data();
752
753 // Iteration starts with the region *after* the full-region-prefix-end.
754 const RegionData* const start_region = sd.addr_to_region_ptr(full_region_prefix_end);
755 // If final region is not full, iteration stops before that region,
756 // because fill_dense_prefix_end assumes that prefix_end <= top.
757 const RegionData* const end_region = sd.addr_to_region_ptr(old_space->top());
758 assert(start_region <= end_region, "inv");
759
760 size_t max_waste = old_space->capacity_in_words() * (MarkSweepDeadRatio / 100.0);
761 const RegionData* cur_region = start_region;
762 for (/* empty */; cur_region < end_region; ++cur_region) {
763 assert(region_size >= cur_region->data_size(), "inv");
764 size_t dead_size = region_size - cur_region->data_size();
765 if (max_waste < dead_size) {
766 break;
767 }
768 max_waste -= dead_size;
769 }
770
771 HeapWord* const prefix_end = sd.region_to_addr(cur_region);
772 assert(sd.is_region_aligned(prefix_end), "postcondition");
773 assert(prefix_end >= full_region_prefix_end, "in-range");
774 assert(prefix_end <= old_space->top(), "in-range");
775 return prefix_end;
776 }
777
778 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) {
779 // Comparing two sizes to decide if filling is required:
780 //
781 // The size of the filler (min-obj-size) is 2 heap words with the default
782 // MinObjAlignment, since both markword and klass take 1 heap word.
783 // With +UseCompactObjectHeaders, the minimum filler size is only one word,
784 // because the Klass* gets encoded in the mark-word.
785 //
786 // The size of the gap (if any) right before dense-prefix-end is
787 // MinObjAlignment.
788 //
789 // Need to fill in the gap only if it's smaller than min-obj-size, and the
790 // filler obj will extend to next region.
791
792 if (MinObjAlignment >= checked_cast<int>(CollectedHeap::min_fill_size())) {
793 return;
794 }
795
796 assert(!UseCompactObjectHeaders, "Compact headers can allocate small objects");
797 assert(CollectedHeap::min_fill_size() == 2, "inv");
798 HeapWord* const dense_prefix_end = dense_prefix(id);
799 assert(_summary_data.is_region_aligned(dense_prefix_end), "precondition");
800 assert(dense_prefix_end <= space(id)->top(), "precondition");
801 if (dense_prefix_end == space(id)->top()) {
802 // Must not have single-word gap right before prefix-end/top.
803 return;
804 }
805 RegionData* const region_after_dense_prefix = _summary_data.addr_to_region_ptr(dense_prefix_end);
806
807 if (region_after_dense_prefix->partial_obj_size() != 0 ||
808 _mark_bitmap.is_marked(dense_prefix_end)) {
809 // The region after the dense prefix starts with live bytes.
810 return;
811 }
812
813 HeapWord* block_start = start_array(id)->block_start_reaching_into_card(dense_prefix_end);
814 if (block_start == dense_prefix_end - 1) {
815 assert(!_mark_bitmap.is_marked(block_start), "inv");
816 // There is exactly one heap word gap right before the dense prefix end, so we need a filler object.
817 // The filler object will extend into region_after_dense_prefix.
818 const size_t obj_len = 2; // min-fill-size
819 HeapWord* const obj_beg = dense_prefix_end - 1;
820 CollectedHeap::fill_with_object(obj_beg, obj_len);
821 _mark_bitmap.mark_obj(obj_beg);
822 _summary_data.addr_to_region_ptr(obj_beg)->add_live_obj(1);
823 region_after_dense_prefix->set_partial_obj_size(1);
824 region_after_dense_prefix->set_partial_obj_addr(obj_beg);
825 assert(start_array(id) != nullptr, "sanity");
826 start_array(id)->update_for_block(obj_beg, obj_beg + obj_len);
827 }
828 }
829
830 bool PSParallelCompact::check_maximum_compaction(size_t total_live_words,
831 MutableSpace* const old_space,
832 HeapWord* full_region_prefix_end) {
833
834 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
835
836 // Check System.GC
837 bool is_max_on_system_gc = UseMaximumCompactionOnSystemGC
838 && GCCause::is_user_requested_gc(heap->gc_cause());
839
840 // Check if all live objs are too much for old-gen.
841 const bool is_old_gen_too_full = (total_live_words >= old_space->capacity_in_words());
842
843 // JVM flags
844 const uint total_invocations = heap->total_full_collections();
845 assert(total_invocations >= _maximum_compaction_gc_num, "sanity");
846 const size_t gcs_since_max = total_invocations - _maximum_compaction_gc_num;
847 const bool is_interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
848
849 // If all regions in old-gen are full
850 const bool is_region_full =
851 full_region_prefix_end >= _summary_data.region_align_down(old_space->top());
852
853 if (is_max_on_system_gc || is_old_gen_too_full || is_interval_ended || is_region_full) {
854 _maximum_compaction_gc_num = total_invocations;
855 return true;
856 }
857
858 return false;
859 }
860
861 void PSParallelCompact::summary_phase()
862 {
863 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
864
865 MutableSpace* const old_space = _space_info[old_space_id].space();
866 {
867 size_t total_live_words = 0;
868 HeapWord* full_region_prefix_end = nullptr;
869 {
870 // old-gen
871 size_t live_words = _summary_data.live_words_in_space(old_space,
872 &full_region_prefix_end);
873 total_live_words += live_words;
874 }
875 // young-gen
876 for (uint i = eden_space_id; i < last_space_id; ++i) {
877 const MutableSpace* space = _space_info[i].space();
878 size_t live_words = _summary_data.live_words_in_space(space);
879 total_live_words += live_words;
880 _space_info[i].set_new_top(space->bottom() + live_words);
881 _space_info[i].set_dense_prefix(space->bottom());
882 }
883
884 bool maximum_compaction = check_maximum_compaction(total_live_words,
885 old_space,
886 full_region_prefix_end);
887 {
888 GCTraceTime(Info, gc, phases) tm("Summary Phase: expand", &_gc_timer);
889 // Try to expand old-gen in order to fit all live objs and waste.
890 size_t target_capacity_bytes = total_live_words * HeapWordSize
891 + old_space->capacity_in_bytes() * (MarkSweepDeadRatio / 100);
892 ParallelScavengeHeap::heap()->old_gen()->try_expand_till_size(target_capacity_bytes);
893 }
894
895 HeapWord* dense_prefix_end = maximum_compaction
896 ? full_region_prefix_end
897 : compute_dense_prefix_for_old_space(old_space,
898 full_region_prefix_end);
899 SpaceId id = old_space_id;
900 _space_info[id].set_dense_prefix(dense_prefix_end);
901
902 if (dense_prefix_end != old_space->bottom()) {
903 fill_dense_prefix_end(id);
904 _summary_data.summarize_dense_prefix(old_space->bottom(), dense_prefix_end);
905 }
906
907 // Compacting objs in [dense_prefix_end, old_space->top())
908 _summary_data.summarize(_space_info[id].split_info(),
909 dense_prefix_end, old_space->top(), nullptr,
910 dense_prefix_end, old_space->end(),
911 _space_info[id].new_top_addr());
912 }
913
914 // Summarize the remaining spaces in the young gen. The initial target space
915 // is the old gen. If a space does not fit entirely into the target, then the
916 // remainder is compacted into the space itself and that space becomes the new
917 // target.
918 SpaceId dst_space_id = old_space_id;
919 HeapWord* dst_space_end = old_space->end();
920 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
921 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
922 const MutableSpace* space = _space_info[id].space();
923 const size_t live = pointer_delta(_space_info[id].new_top(),
924 space->bottom());
925 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
926
927 if (live > 0 && live <= available) {
928 // All the live data will fit.
929 bool done = _summary_data.summarize(_space_info[id].split_info(),
930 space->bottom(), space->top(),
931 nullptr,
932 *new_top_addr, dst_space_end,
933 new_top_addr);
934 assert(done, "space must fit into old gen");
935
936 // Reset the new_top value for the space.
937 _space_info[id].set_new_top(space->bottom());
938 } else if (live > 0) {
939 // Attempt to fit part of the source space into the target space.
940 HeapWord* next_src_addr = nullptr;
941 bool done = _summary_data.summarize(_space_info[id].split_info(),
942 space->bottom(), space->top(),
943 &next_src_addr,
944 *new_top_addr, dst_space_end,
945 new_top_addr);
946 assert(!done, "space should not fit into old gen");
947 assert(next_src_addr != nullptr, "sanity");
948
949 // The source space becomes the new target, so the remainder is compacted
950 // within the space itself.
951 dst_space_id = SpaceId(id);
952 dst_space_end = space->end();
953 new_top_addr = _space_info[id].new_top_addr();
954 done = _summary_data.summarize(_space_info[id].split_info(),
955 next_src_addr, space->top(),
956 nullptr,
957 space->bottom(), dst_space_end,
958 new_top_addr);
959 assert(done, "space must fit when compacted into itself");
960 assert(*new_top_addr <= space->top(), "usage should not grow");
961 }
962 }
963 }
964
965 // This method invokes a full collection. The argument controls whether
966 // soft-refs should be cleared or not.
967 // Note that this method should only be called from the vm_thread while at a
968 // safepoint.
969 bool PSParallelCompact::invoke(bool clear_all_soft_refs) {
970 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
971 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
972 "should be in vm thread");
973
974 SvcGCMarker sgcm(SvcGCMarker::FULL);
975 IsSTWGCActiveMark mark;
976
977 return PSParallelCompact::invoke_no_policy(clear_all_soft_refs);
978 }
979
980 // This method contains no policy. You should probably
981 // be calling invoke() instead.
982 bool PSParallelCompact::invoke_no_policy(bool clear_all_soft_refs) {
983 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
984 assert(ref_processor() != nullptr, "Sanity");
985
986 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
987
988 GCIdMark gc_id_mark;
989 _gc_timer.register_gc_start();
990 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
991
992 GCCause::Cause gc_cause = heap->gc_cause();
993 PSOldGen* old_gen = heap->old_gen();
994 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
995
996 // Make sure data structures are sane, make the heap parsable, and do other
997 // miscellaneous bookkeeping.
998 pre_compact();
999
1000 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
1001
1002 {
1003 const uint active_workers =
1004 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(),
1005 ParallelScavengeHeap::heap()->workers().active_workers(),
1006 Threads::number_of_non_daemon_threads());
1007 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers);
1008
1009 GCTraceCPUTime tcpu(&_gc_tracer);
1010 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause, true);
1011
1012 heap->pre_full_gc_dump(&_gc_timer);
1013
1014 TraceCollectorStats tcs(counters());
1015 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause, "end of major GC");
1016
1017 if (log_is_enabled(Debug, gc, heap, exit)) {
1018 accumulated_time()->start();
1019 }
1020
1021 // Let the size policy know we're starting
1022 size_policy->major_collection_begin();
1023
1024 #if COMPILER2_OR_JVMCI
1025 DerivedPointerTable::clear();
1026 #endif
1027
1028 ref_processor()->start_discovery(clear_all_soft_refs);
1029
1030 marking_phase(&_gc_tracer);
1031
1032 summary_phase();
1033
1034 #if COMPILER2_OR_JVMCI
1035 assert(DerivedPointerTable::is_active(), "Sanity");
1036 DerivedPointerTable::set_active(false);
1037 #endif
1038
1039 forward_to_new_addr();
1040
1041 adjust_pointers();
1042
1043 compact();
1044
1045 ParCompactionManager::_preserved_marks_set->restore(&ParallelScavengeHeap::heap()->workers());
1046
1047 ParCompactionManager::verify_all_region_stack_empty();
1048
1049 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1050 // done before resizing.
1051 post_compact();
1052
1053 size_policy->major_collection_end();
1054
1055 size_policy->sample_old_gen_used_bytes(MAX2(pre_gc_values.old_gen_used(), old_gen->used_in_bytes()));
1056
1057 if (UseAdaptiveSizePolicy) {
1058 heap->resize_after_full_gc();
1059 }
1060
1061 heap->resize_all_tlabs();
1062
1063 // Resize the metaspace capacity after a collection
1064 MetaspaceGC::compute_new_size();
1065
1066 if (log_is_enabled(Debug, gc, heap, exit)) {
1067 accumulated_time()->stop();
1068 }
1069
1070 heap->print_heap_change(pre_gc_values);
1071
1072 // Track memory usage and detect low memory
1073 MemoryService::track_memory_usage();
1074 heap->update_counters();
1075
1076 heap->post_full_gc_dump(&_gc_timer);
1077
1078 size_policy->record_gc_pause_end_instant();
1079 }
1080
1081 heap->gc_epilogue(true);
1082
1083 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1084 Universe::verify("After GC");
1085 }
1086
1087 heap->print_after_gc();
1088 heap->trace_heap_after_gc(&_gc_tracer);
1089
1090 _gc_timer.register_gc_end();
1091
1092 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1093 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1094
1095 return true;
1096 }
1097
1098 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1099 private:
1100 uint _worker_id;
1101
1102 public:
1103 PCAddThreadRootsMarkingTaskClosure(uint worker_id) : _worker_id(worker_id) { }
1104 void do_thread(Thread* thread) {
1105 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1106
1107 ResourceMark rm;
1108
1109 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(_worker_id);
1110
1111 MarkingNMethodClosure mark_and_push_in_blobs(&cm->_mark_and_push_closure,
1112 !NMethodToOopClosure::FixRelocations,
1113 true /* keepalive nmethods */);
1114
1115 thread->oops_do(&cm->_mark_and_push_closure, &mark_and_push_in_blobs);
1116
1117 // Do the real work
1118 cm->follow_marking_stacks();
1119 }
1120 };
1121
1122 void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
1123 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1124
1125 ParCompactionManager* cm =
1126 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1127
1128 do {
1129 ScannerTask task;
1130 if (ParCompactionManager::steal(worker_id, task)) {
1131 cm->follow_contents(task, true);
1132 }
1133 cm->follow_marking_stacks();
1134 } while (!terminator.offer_termination());
1135 }
1136
1137 class MarkFromRootsTask : public WorkerTask {
1138 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
1139 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
1140 TaskTerminator _terminator;
1141 uint _active_workers;
1142
1143 public:
1144 MarkFromRootsTask(uint active_workers) :
1145 WorkerTask("MarkFromRootsTask"),
1146 _strong_roots_scope(active_workers),
1147 _terminator(active_workers, ParCompactionManager::marking_stacks()),
1148 _active_workers(active_workers) {}
1149
1150 virtual void work(uint worker_id) {
1151 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1152 cm->create_marking_stats_cache();
1153 {
1154 CLDToOopClosure cld_closure(&cm->_mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
1155 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
1156
1157 // Do the real work
1158 cm->follow_marking_stacks();
1159 }
1160
1161 {
1162 PCAddThreadRootsMarkingTaskClosure closure(worker_id);
1163 Threads::possibly_parallel_threads_do(_active_workers > 1 /* is_par */, &closure);
1164 }
1165
1166 // Mark from OopStorages
1167 {
1168 _oop_storage_set_par_state.oops_do(&cm->_mark_and_push_closure);
1169 // Do the real work
1170 cm->follow_marking_stacks();
1171 }
1172
1173 if (_active_workers > 1) {
1174 steal_marking_work(_terminator, worker_id);
1175 }
1176 }
1177 };
1178
1179 class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
1180 TaskTerminator _terminator;
1181
1182 public:
1183 ParallelCompactRefProcProxyTask(uint max_workers)
1184 : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers),
1185 _terminator(_max_workers, ParCompactionManager::marking_stacks()) {}
1186
1187 void work(uint worker_id) override {
1188 assert(worker_id < _max_workers, "sanity");
1189 ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
1190 BarrierEnqueueDiscoveredFieldClosure enqueue;
1191 ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
1192 _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &cm->_mark_and_push_closure, &enqueue, &complete_gc);
1193 }
1194
1195 void prepare_run_task_hook() override {
1196 _terminator.reset_for_reuse(_queue_count);
1197 }
1198 };
1199
1200 static void flush_marking_stats_cache(const uint num_workers) {
1201 for (uint i = 0; i < num_workers; ++i) {
1202 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(i);
1203 cm->flush_and_destroy_marking_stats_cache();
1204 }
1205 }
1206
1207 void PSParallelCompact::marking_phase(ParallelOldTracer *gc_tracer) {
1208 // Recursively traverse all live objects and mark them
1209 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
1210
1211 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1212
1213 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
1214 {
1215 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
1216
1217 MarkFromRootsTask task(active_gc_threads);
1218 ParallelScavengeHeap::heap()->workers().run_task(&task);
1219 }
1220
1221 // Process reference objects found during marking
1222 {
1223 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
1224
1225 ReferenceProcessorStats stats;
1226 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
1227
1228 ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues());
1229 stats = ref_processor()->process_discovered_references(task, &ParallelScavengeHeap::heap()->workers(), pt);
1230
1231 gc_tracer->report_gc_reference_stats(stats);
1232 pt.print_all_references();
1233 }
1234
1235 {
1236 GCTraceTime(Debug, gc, phases) tm("Flush Marking Stats", &_gc_timer);
1237
1238 flush_marking_stats_cache(active_gc_threads);
1239 }
1240
1241 // This is the point where the entire marking should have completed.
1242 ParCompactionManager::verify_all_marking_stack_empty();
1243
1244 {
1245 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
1246 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(),
1247 is_alive_closure(),
1248 &do_nothing_cl,
1249 1);
1250 }
1251
1252 {
1253 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
1254
1255 ClassUnloadingContext ctx(1 /* num_nmethod_unlink_workers */,
1256 false /* unregister_nmethods_during_purge */,
1257 false /* lock_nmethod_free_separately */);
1258
1259 bool unloading_occurred;
1260 {
1261 CodeCache::UnlinkingScope scope(is_alive_closure());
1262
1263 // Follow system dictionary roots and unload classes.
1264 unloading_occurred = SystemDictionary::do_unloading(&_gc_timer);
1265
1266 // Unload nmethods.
1267 CodeCache::do_unloading(unloading_occurred);
1268 }
1269
1270 {
1271 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
1272 // Release unloaded nmethod's memory.
1273 ctx.purge_nmethods();
1274 }
1275 {
1276 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", &_gc_timer);
1277 ParallelScavengeHeap::heap()->prune_unlinked_nmethods();
1278 }
1279 {
1280 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
1281 ctx.free_nmethods();
1282 }
1283
1284 // Prune dead klasses from subklass/sibling/implementor lists.
1285 Klass::clean_weak_klass_links(unloading_occurred);
1286
1287 // Clean JVMCI metadata handles.
1288 JVMCI_ONLY(JVMCI::do_unloading(unloading_occurred));
1289 {
1290 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1291 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", gc_timer());
1292 ClassLoaderDataGraph::purge(true /* at_safepoint */);
1293 DEBUG_ONLY(MetaspaceUtils::verify();)
1294 }
1295 }
1296
1297 {
1298 GCTraceTime(Debug, gc, phases) tm("Report Object Count", &_gc_timer);
1299 _gc_tracer.report_object_count_after_gc(is_alive_closure(), &ParallelScavengeHeap::heap()->workers());
1300 }
1301 #if TASKQUEUE_STATS
1302 ParCompactionManager::print_and_reset_taskqueue_stats();
1303 #endif
1304 }
1305
1306 template<typename Func>
1307 void PSParallelCompact::adjust_in_space_helper(SpaceId id, volatile uint* claim_counter, Func&& on_stripe) {
1308 MutableSpace* sp = PSParallelCompact::space(id);
1309 HeapWord* const bottom = sp->bottom();
1310 HeapWord* const top = sp->top();
1311 if (bottom == top) {
1312 return;
1313 }
1314
1315 const uint num_regions_per_stripe = 2;
1316 const size_t region_size = ParallelCompactData::RegionSize;
1317 const size_t stripe_size = num_regions_per_stripe * region_size;
1318
1319 while (true) {
1320 uint counter = Atomic::fetch_then_add(claim_counter, num_regions_per_stripe);
1321 HeapWord* cur_stripe = bottom + counter * region_size;
1322 if (cur_stripe >= top) {
1323 break;
1324 }
1325 HeapWord* stripe_end = MIN2(cur_stripe + stripe_size, top);
1326 on_stripe(cur_stripe, stripe_end);
1327 }
1328 }
1329
1330 void PSParallelCompact::adjust_in_old_space(volatile uint* claim_counter) {
1331 // Regions in old-space shouldn't be split.
1332 assert(!_space_info[old_space_id].split_info().is_valid(), "inv");
1333
1334 auto scan_obj_with_limit = [&] (HeapWord* obj_start, HeapWord* left, HeapWord* right) {
1335 assert(mark_bitmap()->is_marked(obj_start), "inv");
1336 oop obj = cast_to_oop(obj_start);
1337 return obj->oop_iterate_size(&pc_adjust_pointer_closure, MemRegion(left, right));
1338 };
1339
1340 adjust_in_space_helper(old_space_id, claim_counter, [&] (HeapWord* stripe_start, HeapWord* stripe_end) {
1341 assert(_summary_data.is_region_aligned(stripe_start), "inv");
1342 RegionData* cur_region = _summary_data.addr_to_region_ptr(stripe_start);
1343 HeapWord* obj_start;
1344 if (cur_region->partial_obj_size() != 0) {
1345 obj_start = cur_region->partial_obj_addr();
1346 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1347 } else {
1348 obj_start = stripe_start;
1349 }
1350
1351 while (obj_start < stripe_end) {
1352 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1353 if (obj_start >= stripe_end) {
1354 break;
1355 }
1356 obj_start += scan_obj_with_limit(obj_start, stripe_start, stripe_end);
1357 }
1358 });
1359 }
1360
1361 void PSParallelCompact::adjust_in_young_space(SpaceId id, volatile uint* claim_counter) {
1362 adjust_in_space_helper(id, claim_counter, [](HeapWord* stripe_start, HeapWord* stripe_end) {
1363 HeapWord* obj_start = stripe_start;
1364 while (obj_start < stripe_end) {
1365 obj_start = mark_bitmap()->find_obj_beg(obj_start, stripe_end);
1366 if (obj_start >= stripe_end) {
1367 break;
1368 }
1369 oop obj = cast_to_oop(obj_start);
1370 obj_start += obj->oop_iterate_size(&pc_adjust_pointer_closure);
1371 }
1372 });
1373 }
1374
1375 void PSParallelCompact::adjust_pointers_in_spaces(uint worker_id, volatile uint* claim_counters) {
1376 auto start_time = Ticks::now();
1377 adjust_in_old_space(&claim_counters[0]);
1378 for (uint id = eden_space_id; id < last_space_id; ++id) {
1379 adjust_in_young_space(SpaceId(id), &claim_counters[id]);
1380 }
1381 log_trace(gc, phases)("adjust_pointers_in_spaces worker %u: %.3f ms", worker_id, (Ticks::now() - start_time).seconds() * 1000);
1382 }
1383
1384 class PSAdjustTask final : public WorkerTask {
1385 SubTasksDone _sub_tasks;
1386 WeakProcessor::Task _weak_proc_task;
1387 OopStorageSetStrongParState<false, false> _oop_storage_iter;
1388 uint _nworkers;
1389 volatile uint _claim_counters[PSParallelCompact::last_space_id] = {};
1390
1391 enum PSAdjustSubTask {
1392 PSAdjustSubTask_code_cache,
1393
1394 PSAdjustSubTask_num_elements
1395 };
1396
1397 public:
1398 PSAdjustTask(uint nworkers) :
1399 WorkerTask("PSAdjust task"),
1400 _sub_tasks(PSAdjustSubTask_num_elements),
1401 _weak_proc_task(nworkers),
1402 _nworkers(nworkers) {
1403
1404 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
1405 if (nworkers > 1) {
1406 Threads::change_thread_claim_token();
1407 }
1408 }
1409
1410 ~PSAdjustTask() {
1411 Threads::assert_all_threads_claimed();
1412 }
1413
1414 void work(uint worker_id) {
1415 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1416 cm->preserved_marks()->adjust_during_full_gc();
1417 {
1418 // adjust pointers in all spaces
1419 PSParallelCompact::adjust_pointers_in_spaces(worker_id, _claim_counters);
1420 }
1421 {
1422 ResourceMark rm;
1423 Threads::possibly_parallel_oops_do(_nworkers > 1, &pc_adjust_pointer_closure, nullptr);
1424 }
1425 _oop_storage_iter.oops_do(&pc_adjust_pointer_closure);
1426 {
1427 CLDToOopClosure cld_closure(&pc_adjust_pointer_closure, ClassLoaderData::_claim_stw_fullgc_adjust);
1428 ClassLoaderDataGraph::cld_do(&cld_closure);
1429 }
1430 {
1431 AlwaysTrueClosure always_alive;
1432 _weak_proc_task.work(worker_id, &always_alive, &pc_adjust_pointer_closure);
1433 }
1434 if (_sub_tasks.try_claim_task(PSAdjustSubTask_code_cache)) {
1435 NMethodToOopClosure adjust_code(&pc_adjust_pointer_closure, NMethodToOopClosure::FixRelocations);
1436 CodeCache::nmethods_do(&adjust_code);
1437 }
1438 _sub_tasks.all_tasks_claimed();
1439 }
1440 };
1441
1442 void PSParallelCompact::adjust_pointers() {
1443 // Adjust the pointers to reflect the new locations
1444 GCTraceTime(Info, gc, phases) tm("Adjust Pointers", &_gc_timer);
1445 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1446 PSAdjustTask task(nworkers);
1447 ParallelScavengeHeap::heap()->workers().run_task(&task);
1448 }
1449
1450 // Split [start, end) evenly for a number of workers and return the
1451 // range for worker_id.
1452 static void split_regions_for_worker(size_t start, size_t end,
1453 uint worker_id, uint num_workers,
1454 size_t* worker_start, size_t* worker_end) {
1455 assert(start < end, "precondition");
1456 assert(num_workers > 0, "precondition");
1457 assert(worker_id < num_workers, "precondition");
1458
1459 size_t num_regions = end - start;
1460 size_t num_regions_per_worker = num_regions / num_workers;
1461 size_t remainder = num_regions % num_workers;
1462 // The first few workers will get one extra.
1463 *worker_start = start + worker_id * num_regions_per_worker
1464 + MIN2(checked_cast<size_t>(worker_id), remainder);
1465 *worker_end = *worker_start + num_regions_per_worker
1466 + (worker_id < remainder ? 1 : 0);
1467 }
1468
1469 void PSParallelCompact::forward_to_new_addr() {
1470 GCTraceTime(Info, gc, phases) tm("Forward", &_gc_timer);
1471 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1472
1473 struct ForwardTask final : public WorkerTask {
1474 uint _num_workers;
1475
1476 explicit ForwardTask(uint num_workers) :
1477 WorkerTask("PSForward task"),
1478 _num_workers(num_workers) {}
1479
1480 static void forward_objs_in_range(ParCompactionManager* cm,
1481 HeapWord* start,
1482 HeapWord* end,
1483 HeapWord* destination) {
1484 HeapWord* cur_addr = start;
1485 HeapWord* new_addr = destination;
1486
1487 while (cur_addr < end) {
1488 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, end);
1489 if (cur_addr >= end) {
1490 return;
1491 }
1492 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1493 oop obj = cast_to_oop(cur_addr);
1494 if (new_addr != cur_addr) {
1495 cm->preserved_marks()->push_if_necessary(obj, obj->mark());
1496 FullGCForwarding::forward_to(obj, cast_to_oop(new_addr));
1497 }
1498 size_t obj_size = obj->size();
1499 new_addr += obj_size;
1500 cur_addr += obj_size;
1501 }
1502 }
1503
1504 void work(uint worker_id) override {
1505 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1506 for (uint id = old_space_id; id < last_space_id; ++id) {
1507 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1508 HeapWord* dense_prefix_addr = dense_prefix(SpaceId(id));
1509 HeapWord* top = sp->top();
1510
1511 if (dense_prefix_addr == top) {
1512 // Empty space
1513 continue;
1514 }
1515
1516 const SplitInfo& split_info = _space_info[SpaceId(id)].split_info();
1517 size_t dense_prefix_region = _summary_data.addr_to_region_idx(dense_prefix_addr);
1518 size_t top_region = _summary_data.addr_to_region_idx(_summary_data.region_align_up(top));
1519 size_t start_region;
1520 size_t end_region;
1521 split_regions_for_worker(dense_prefix_region, top_region,
1522 worker_id, _num_workers,
1523 &start_region, &end_region);
1524 for (size_t cur_region = start_region; cur_region < end_region; ++cur_region) {
1525 RegionData* region_ptr = _summary_data.region(cur_region);
1526 size_t partial_obj_size = region_ptr->partial_obj_size();
1527
1528 if (partial_obj_size == ParallelCompactData::RegionSize) {
1529 // No obj-start
1530 continue;
1531 }
1532
1533 HeapWord* region_start = _summary_data.region_to_addr(cur_region);
1534 HeapWord* region_end = region_start + ParallelCompactData::RegionSize;
1535
1536 if (split_info.is_split(cur_region)) {
1537 // Part 1: will be relocated to space-1
1538 HeapWord* preceding_destination = split_info.preceding_destination();
1539 HeapWord* split_point = split_info.split_point();
1540 forward_objs_in_range(cm, region_start + partial_obj_size, split_point, preceding_destination + partial_obj_size);
1541
1542 // Part 2: will be relocated to space-2
1543 HeapWord* destination = region_ptr->destination();
1544 forward_objs_in_range(cm, split_point, region_end, destination);
1545 } else {
1546 HeapWord* destination = region_ptr->destination();
1547 forward_objs_in_range(cm, region_start + partial_obj_size, region_end, destination + partial_obj_size);
1548 }
1549 }
1550 }
1551 }
1552 } task(nworkers);
1553
1554 ParallelScavengeHeap::heap()->workers().run_task(&task);
1555 DEBUG_ONLY(verify_forward();)
1556 }
1557
1558 #ifdef ASSERT
1559 void PSParallelCompact::verify_forward() {
1560 HeapWord* const old_dense_prefix_addr = dense_prefix(SpaceId(old_space_id));
1561 RegionData* old_region = _summary_data.region(_summary_data.addr_to_region_idx(old_dense_prefix_addr));
1562 HeapWord* bump_ptr = old_region->partial_obj_size() != 0
1563 ? old_dense_prefix_addr + old_region->partial_obj_size()
1564 : old_dense_prefix_addr;
1565 SpaceId bump_ptr_space = old_space_id;
1566
1567 for (uint id = old_space_id; id < last_space_id; ++id) {
1568 MutableSpace* sp = PSParallelCompact::space(SpaceId(id));
1569 HeapWord* dense_prefix_addr = dense_prefix(SpaceId(id));
1570 HeapWord* top = sp->top();
1571 HeapWord* cur_addr = dense_prefix_addr;
1572
1573 while (cur_addr < top) {
1574 cur_addr = mark_bitmap()->find_obj_beg(cur_addr, top);
1575 if (cur_addr >= top) {
1576 break;
1577 }
1578 assert(mark_bitmap()->is_marked(cur_addr), "inv");
1579 assert(bump_ptr <= _space_info[bump_ptr_space].new_top(), "inv");
1580 // Move to the space containing cur_addr
1581 if (bump_ptr == _space_info[bump_ptr_space].new_top()) {
1582 bump_ptr = space(space_id(cur_addr))->bottom();
1583 bump_ptr_space = space_id(bump_ptr);
1584 }
1585 oop obj = cast_to_oop(cur_addr);
1586 if (cur_addr == bump_ptr) {
1587 assert(!FullGCForwarding::is_forwarded(obj), "inv");
1588 } else {
1589 assert(FullGCForwarding::forwardee(obj) == cast_to_oop(bump_ptr), "inv");
1590 }
1591 bump_ptr += obj->size();
1592 cur_addr += obj->size();
1593 }
1594 }
1595 }
1596 #endif
1597
1598 // Helper class to print 8 region numbers per line and then print the total at the end.
1599 class FillableRegionLogger : public StackObj {
1600 private:
1601 Log(gc, compaction) log;
1602 static const int LineLength = 8;
1603 size_t _regions[LineLength];
1604 int _next_index;
1605 bool _enabled;
1606 size_t _total_regions;
1607 public:
1608 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
1609 ~FillableRegionLogger() {
1610 log.trace("%zu initially fillable regions", _total_regions);
1611 }
1612
1613 void print_line() {
1614 if (!_enabled || _next_index == 0) {
1615 return;
1616 }
1617 FormatBuffer<> line("Fillable: ");
1618 for (int i = 0; i < _next_index; i++) {
1619 line.append(" %7zu", _regions[i]);
1620 }
1621 log.trace("%s", line.buffer());
1622 _next_index = 0;
1623 }
1624
1625 void handle(size_t region) {
1626 if (!_enabled) {
1627 return;
1628 }
1629 _regions[_next_index++] = region;
1630 if (_next_index == LineLength) {
1631 print_line();
1632 }
1633 _total_regions++;
1634 }
1635 };
1636
1637 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
1638 {
1639 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
1640
1641 // Find the threads that are active
1642 uint worker_id = 0;
1643
1644 // Find all regions that are available (can be filled immediately) and
1645 // distribute them to the thread stacks. The iteration is done in reverse
1646 // order (high to low) so the regions will be removed in ascending order.
1647
1648 const ParallelCompactData& sd = PSParallelCompact::summary_data();
1649
1650 // id + 1 is used to test termination so unsigned can
1651 // be used with an old_space_id == 0.
1652 FillableRegionLogger region_logger;
1653 for (unsigned int id = last_space_id - 1; id + 1 > old_space_id; --id) {
1654 SpaceInfo* const space_info = _space_info + id;
1655 HeapWord* const new_top = space_info->new_top();
1656
1657 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
1658 const size_t end_region =
1659 sd.addr_to_region_idx(sd.region_align_up(new_top));
1660
1661 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
1662 if (sd.region(cur)->claim_unsafe()) {
1663 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1664 bool result = sd.region(cur)->mark_normal();
1665 assert(result, "Must succeed at this point.");
1666 cm->region_stack()->push(cur);
1667 region_logger.handle(cur);
1668 // Assign regions to tasks in round-robin fashion.
1669 if (++worker_id == parallel_gc_threads) {
1670 worker_id = 0;
1671 }
1672 }
1673 }
1674 region_logger.print_line();
1675 }
1676 }
1677
1678 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
1679 assert(ParallelScavengeHeap::heap()->is_stw_gc_active(), "called outside gc");
1680
1681 ParCompactionManager* cm =
1682 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1683
1684 // Drain the stacks that have been preloaded with regions
1685 // that are ready to fill.
1686
1687 cm->drain_region_stacks();
1688
1689 guarantee(cm->region_stack()->is_empty(), "Not empty");
1690
1691 size_t region_index = 0;
1692
1693 while (true) {
1694 if (ParCompactionManager::steal(worker_id, region_index)) {
1695 PSParallelCompact::fill_and_update_region(cm, region_index);
1696 cm->drain_region_stacks();
1697 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
1698 // Fill and update an unavailable region with the help of a shadow region
1699 PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
1700 cm->drain_region_stacks();
1701 } else {
1702 if (terminator->offer_termination()) {
1703 break;
1704 }
1705 // Go around again.
1706 }
1707 }
1708 }
1709
1710 class FillDensePrefixAndCompactionTask: public WorkerTask {
1711 uint _num_workers;
1712 TaskTerminator _terminator;
1713
1714 public:
1715 FillDensePrefixAndCompactionTask(uint active_workers) :
1716 WorkerTask("FillDensePrefixAndCompactionTask"),
1717 _num_workers(active_workers),
1718 _terminator(active_workers, ParCompactionManager::region_task_queues()) {
1719 }
1720
1721 virtual void work(uint worker_id) {
1722 {
1723 auto start = Ticks::now();
1724 PSParallelCompact::fill_dead_objs_in_dense_prefix(worker_id, _num_workers);
1725 log_trace(gc, phases)("Fill dense prefix by worker %u: %.3f ms", worker_id, (Ticks::now() - start).seconds() * 1000);
1726 }
1727 compaction_with_stealing_work(&_terminator, worker_id);
1728 }
1729 };
1730
1731 void PSParallelCompact::fill_range_in_dense_prefix(HeapWord* start, HeapWord* end) {
1732 #ifdef ASSERT
1733 {
1734 assert(start < end, "precondition");
1735 assert(mark_bitmap()->find_obj_beg(start, end) == end, "precondition");
1736 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1737 if (start != bottom) {
1738 HeapWord* obj_start = mark_bitmap()->find_obj_beg_reverse(bottom, start);
1739 HeapWord* after_obj = obj_start + cast_to_oop(obj_start)->size();
1740 assert(after_obj == start, "precondition");
1741 }
1742 }
1743 #endif
1744
1745 CollectedHeap::fill_with_objects(start, pointer_delta(end, start));
1746 HeapWord* addr = start;
1747 do {
1748 size_t size = cast_to_oop(addr)->size();
1749 start_array(old_space_id)->update_for_block(addr, addr + size);
1750 addr += size;
1751 } while (addr < end);
1752 }
1753
1754 void PSParallelCompact::fill_dead_objs_in_dense_prefix(uint worker_id, uint num_workers) {
1755 ParMarkBitMap* bitmap = mark_bitmap();
1756
1757 HeapWord* const bottom = _space_info[old_space_id].space()->bottom();
1758 HeapWord* const prefix_end = dense_prefix(old_space_id);
1759
1760 if (bottom == prefix_end) {
1761 return;
1762 }
1763
1764 size_t bottom_region = _summary_data.addr_to_region_idx(bottom);
1765 size_t prefix_end_region = _summary_data.addr_to_region_idx(prefix_end);
1766
1767 size_t start_region;
1768 size_t end_region;
1769 split_regions_for_worker(bottom_region, prefix_end_region,
1770 worker_id, num_workers,
1771 &start_region, &end_region);
1772
1773 if (start_region == end_region) {
1774 return;
1775 }
1776
1777 HeapWord* const start_addr = _summary_data.region_to_addr(start_region);
1778 HeapWord* const end_addr = _summary_data.region_to_addr(end_region);
1779
1780 // Skip live partial obj (if any) from previous region.
1781 HeapWord* cur_addr;
1782 RegionData* start_region_ptr = _summary_data.region(start_region);
1783 if (start_region_ptr->partial_obj_size() != 0) {
1784 HeapWord* partial_obj_start = start_region_ptr->partial_obj_addr();
1785 assert(bitmap->is_marked(partial_obj_start), "inv");
1786 cur_addr = partial_obj_start + cast_to_oop(partial_obj_start)->size();
1787 } else {
1788 cur_addr = start_addr;
1789 }
1790
1791 // end_addr is inclusive to handle regions starting with dead space.
1792 while (cur_addr <= end_addr) {
1793 // Use prefix_end to handle trailing obj in each worker region-chunk.
1794 HeapWord* live_start = bitmap->find_obj_beg(cur_addr, prefix_end);
1795 if (cur_addr != live_start) {
1796 // Only worker 0 handles proceeding dead space.
1797 if (cur_addr != start_addr || worker_id == 0) {
1798 fill_range_in_dense_prefix(cur_addr, live_start);
1799 }
1800 }
1801 if (live_start >= end_addr) {
1802 break;
1803 }
1804 assert(bitmap->is_marked(live_start), "inv");
1805 cur_addr = live_start + cast_to_oop(live_start)->size();
1806 }
1807 }
1808
1809 void PSParallelCompact::compact() {
1810 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
1811
1812 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1813
1814 initialize_shadow_regions(active_gc_threads);
1815 prepare_region_draining_tasks(active_gc_threads);
1816
1817 {
1818 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
1819
1820 FillDensePrefixAndCompactionTask task(active_gc_threads);
1821 ParallelScavengeHeap::heap()->workers().run_task(&task);
1822
1823 #ifdef ASSERT
1824 verify_filler_in_dense_prefix();
1825
1826 // Verify that all regions have been processed.
1827 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1828 verify_complete(SpaceId(id));
1829 }
1830 #endif
1831 }
1832 }
1833
1834 #ifdef ASSERT
1835 void PSParallelCompact::verify_filler_in_dense_prefix() {
1836 HeapWord* bottom = _space_info[old_space_id].space()->bottom();
1837 HeapWord* dense_prefix_end = dense_prefix(old_space_id);
1838 HeapWord* cur_addr = bottom;
1839 while (cur_addr < dense_prefix_end) {
1840 oop obj = cast_to_oop(cur_addr);
1841 oopDesc::verify(obj);
1842 if (!mark_bitmap()->is_marked(cur_addr)) {
1843 Klass* k = cast_to_oop(cur_addr)->klass();
1844 assert(k == Universe::fillerArrayKlass() || k == vmClasses::FillerObject_klass(), "inv");
1845 }
1846 cur_addr += obj->size();
1847 }
1848 }
1849
1850 void PSParallelCompact::verify_complete(SpaceId space_id) {
1851 // All Regions served as compaction targets, from dense_prefix() to
1852 // new_top(), should be marked as filled and all Regions between new_top()
1853 // and top() should be available (i.e., should have been emptied).
1854 ParallelCompactData& sd = summary_data();
1855 SpaceInfo si = _space_info[space_id];
1856 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
1857 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
1858 const size_t beg_region = sd.addr_to_region_idx(si.dense_prefix());
1859 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
1860 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
1861
1862 size_t cur_region;
1863 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
1864 const RegionData* const c = sd.region(cur_region);
1865 assert(c->completed(), "region %zu not filled: destination_count=%u",
1866 cur_region, c->destination_count());
1867 }
1868
1869 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
1870 const RegionData* const c = sd.region(cur_region);
1871 assert(c->available(), "region %zu not empty: destination_count=%u",
1872 cur_region, c->destination_count());
1873 }
1874 }
1875 #endif // #ifdef ASSERT
1876
1877 // Return the SpaceId for the space containing addr. If addr is not in the
1878 // heap, last_space_id is returned. In debug mode it expects the address to be
1879 // in the heap and asserts such.
1880 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
1881 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
1882
1883 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1884 if (_space_info[id].space()->contains(addr)) {
1885 return SpaceId(id);
1886 }
1887 }
1888
1889 assert(false, "no space contains the addr");
1890 return last_space_id;
1891 }
1892
1893 // Skip over count live words starting from beg, and return the address of the
1894 // next live word. Callers must also ensure that there are enough live words in
1895 // the range [beg, end) to skip.
1896 HeapWord* PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
1897 {
1898 ParMarkBitMap* m = mark_bitmap();
1899 HeapWord* cur_addr = beg;
1900 while (true) {
1901 cur_addr = m->find_obj_beg(cur_addr, end);
1902 assert(cur_addr < end, "inv");
1903 size_t obj_size = cast_to_oop(cur_addr)->size();
1904 // Strictly greater-than
1905 if (obj_size > count) {
1906 return cur_addr + count;
1907 }
1908 count -= obj_size;
1909 cur_addr += obj_size;
1910 }
1911 }
1912
1913 // On starting to fill a destination region (dest-region), we need to know the
1914 // location of the word that will be at the start of the dest-region after
1915 // compaction. A dest-region can have one or more source regions, but only the
1916 // first source-region contains this location. This location is retrieved by
1917 // calling `first_src_addr` on a dest-region.
1918 // Conversely, a source-region has a dest-region which holds the destination of
1919 // the first live word on this source-region, based on which the destination
1920 // for the rest of live words can be derived.
1921 //
1922 // Note:
1923 // There is some complication due to space-boundary-fragmentation (an obj can't
1924 // cross space-boundary) -- a source-region may be split and behave like two
1925 // distinct regions with their own dest-region, as depicted below.
1926 //
1927 // source-region: region-n
1928 //
1929 // **********************
1930 // | A|A~~~~B|B |
1931 // **********************
1932 // n-1 n n+1
1933 //
1934 // AA, BB denote two live objs. ~~~~ denotes unknown number of live objs.
1935 //
1936 // Assuming the dest-region for region-n is the final region before
1937 // old-space-end and its first-live-word is the middle of AA, the heap content
1938 // will look like the following after compaction:
1939 //
1940 // ************** *************
1941 // A|A~~~~ | |BB |
1942 // ************** *************
1943 // ^ ^
1944 // | old-space-end | eden-space-start
1945 //
1946 // Therefore, in this example, region-n will have two dest-regions:
1947 // 1. the final region in old-space
1948 // 2. the first region in eden-space.
1949 // To handle this special case, we introduce the concept of split-region, whose
1950 // contents are relocated to two spaces. `SplitInfo` captures all necessary
1951 // info about the split, the first part, spliting-point, and the second part.
1952 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
1953 SpaceId src_space_id,
1954 size_t src_region_idx)
1955 {
1956 const size_t RegionSize = ParallelCompactData::RegionSize;
1957 const ParallelCompactData& sd = summary_data();
1958 assert(sd.is_region_aligned(dest_addr), "precondition");
1959
1960 const RegionData* const src_region_ptr = sd.region(src_region_idx);
1961 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
1962
1963 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
1964 HeapWord* const src_region_destination = src_region_ptr->destination();
1965
1966 HeapWord* const region_start = sd.region_to_addr(src_region_idx);
1967 HeapWord* const region_end = sd.region_to_addr(src_region_idx) + RegionSize;
1968
1969 // Identify the actual destination for the first live words on this region,
1970 // taking split-region into account.
1971 HeapWord* region_start_destination;
1972 const SplitInfo& split_info = _space_info[src_space_id].split_info();
1973 if (split_info.is_split(src_region_idx)) {
1974 // The second part of this split region; use the recorded split point.
1975 if (dest_addr == src_region_destination) {
1976 return split_info.split_point();
1977 }
1978 region_start_destination = split_info.preceding_destination();
1979 } else {
1980 region_start_destination = src_region_destination;
1981 }
1982
1983 // Calculate the offset to be skipped
1984 size_t words_to_skip = pointer_delta(dest_addr, region_start_destination);
1985
1986 HeapWord* result;
1987 if (partial_obj_size > words_to_skip) {
1988 result = region_start + words_to_skip;
1989 } else {
1990 words_to_skip -= partial_obj_size;
1991 result = skip_live_words(region_start + partial_obj_size, region_end, words_to_skip);
1992 }
1993
1994 if (split_info.is_split(src_region_idx)) {
1995 assert(result < split_info.split_point(), "postcondition");
1996 } else {
1997 assert(result < region_end, "postcondition");
1998 }
1999
2000 return result;
2001 }
2002
2003 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2004 SpaceId src_space_id,
2005 size_t beg_region,
2006 HeapWord* end_addr)
2007 {
2008 ParallelCompactData& sd = summary_data();
2009
2010 #ifdef ASSERT
2011 MutableSpace* const src_space = _space_info[src_space_id].space();
2012 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2013 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2014 "src_space_id does not match beg_addr");
2015 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2016 "src_space_id does not match end_addr");
2017 #endif // #ifdef ASSERT
2018
2019 RegionData* const beg = sd.region(beg_region);
2020 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2021
2022 // Regions up to new_top() are enqueued if they become available.
2023 HeapWord* const new_top = _space_info[src_space_id].new_top();
2024 RegionData* const enqueue_end =
2025 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2026
2027 for (RegionData* cur = beg; cur < end; ++cur) {
2028 assert(cur->data_size() > 0, "region must have live data");
2029 cur->decrement_destination_count();
2030 if (cur < enqueue_end && cur->available() && cur->claim()) {
2031 if (cur->mark_normal()) {
2032 cm->push_region(sd.region(cur));
2033 } else if (cur->mark_copied()) {
2034 // Try to copy the content of the shadow region back to its corresponding
2035 // heap region if the shadow region is filled. Otherwise, the GC thread
2036 // fills the shadow region will copy the data back (see
2037 // MoveAndUpdateShadowClosure::complete_region).
2038 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2039 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2040 cur->set_completed();
2041 }
2042 }
2043 }
2044 }
2045
2046 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2047 SpaceId& src_space_id,
2048 HeapWord*& src_space_top,
2049 HeapWord* end_addr)
2050 {
2051 ParallelCompactData& sd = PSParallelCompact::summary_data();
2052
2053 size_t src_region_idx = 0;
2054
2055 // Skip empty regions (if any) up to the top of the space.
2056 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2057 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2058 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2059 const RegionData* const top_region_ptr = sd.addr_to_region_ptr(top_aligned_up);
2060
2061 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2062 ++src_region_ptr;
2063 }
2064
2065 if (src_region_ptr < top_region_ptr) {
2066 // Found the first non-empty region in the same space.
2067 src_region_idx = sd.region(src_region_ptr);
2068 closure.set_source(sd.region_to_addr(src_region_idx));
2069 return src_region_idx;
2070 }
2071
2072 // Switch to a new source space and find the first non-empty region.
2073 uint space_id = src_space_id + 1;
2074 assert(space_id < last_space_id, "not enough spaces");
2075
2076 for (/* empty */; space_id < last_space_id; ++space_id) {
2077 HeapWord* bottom = _space_info[space_id].space()->bottom();
2078 HeapWord* top = _space_info[space_id].space()->top();
2079 // Skip empty space
2080 if (bottom == top) {
2081 continue;
2082 }
2083
2084 // Identify the first region that contains live words in this space
2085 size_t cur_region = sd.addr_to_region_idx(bottom);
2086 size_t end_region = sd.addr_to_region_idx(sd.region_align_up(top));
2087
2088 for (/* empty */ ; cur_region < end_region; ++cur_region) {
2089 RegionData* cur = sd.region(cur_region);
2090 if (cur->live_obj_size() > 0) {
2091 HeapWord* region_start_addr = sd.region_to_addr(cur_region);
2092
2093 src_space_id = SpaceId(space_id);
2094 src_space_top = top;
2095 closure.set_source(region_start_addr);
2096 return cur_region;
2097 }
2098 }
2099 }
2100
2101 ShouldNotReachHere();
2102 }
2103
2104 HeapWord* PSParallelCompact::partial_obj_end(HeapWord* region_start_addr) {
2105 ParallelCompactData& sd = summary_data();
2106 assert(sd.is_region_aligned(region_start_addr), "precondition");
2107
2108 // Use per-region partial_obj_size to locate the end of the obj, that extends
2109 // to region_start_addr.
2110 size_t start_region_idx = sd.addr_to_region_idx(region_start_addr);
2111 size_t end_region_idx = sd.region_count();
2112 size_t accumulated_size = 0;
2113 for (size_t region_idx = start_region_idx; region_idx < end_region_idx; ++region_idx) {
2114 size_t cur_partial_obj_size = sd.region(region_idx)->partial_obj_size();
2115 accumulated_size += cur_partial_obj_size;
2116 if (cur_partial_obj_size != ParallelCompactData::RegionSize) {
2117 break;
2118 }
2119 }
2120 return region_start_addr + accumulated_size;
2121 }
2122
2123 // Use region_idx as the destination region, and evacuate all live objs on its
2124 // source regions to this destination region.
2125 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2126 {
2127 ParMarkBitMap* const bitmap = mark_bitmap();
2128 ParallelCompactData& sd = summary_data();
2129 RegionData* const region_ptr = sd.region(region_idx);
2130
2131 // Get the source region and related info.
2132 size_t src_region_idx = region_ptr->source_region();
2133 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2134 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2135 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2136
2137 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2138
2139 // Adjust src_region_idx to prepare for decrementing destination counts (the
2140 // destination count is not decremented when a region is copied to itself).
2141 if (src_region_idx == region_idx) {
2142 src_region_idx += 1;
2143 }
2144
2145 // source-region:
2146 //
2147 // **********
2148 // | ~~~ |
2149 // **********
2150 // ^
2151 // |-- closure.source() / first_src_addr
2152 //
2153 //
2154 // ~~~ : live words
2155 //
2156 // destination-region:
2157 //
2158 // **********
2159 // | |
2160 // **********
2161 // ^
2162 // |-- region-start
2163 if (bitmap->is_unmarked(closure.source())) {
2164 // An object overflows the previous destination region, so this
2165 // destination region should copy the remainder of the object or as much as
2166 // will fit.
2167 HeapWord* const old_src_addr = closure.source();
2168 {
2169 HeapWord* region_start = sd.region_align_down(closure.source());
2170 HeapWord* obj_start = bitmap->find_obj_beg_reverse(region_start, closure.source());
2171 HeapWord* obj_end;
2172 if (obj_start != closure.source()) {
2173 assert(bitmap->is_marked(obj_start), "inv");
2174 // Found the actual obj-start, try to find the obj-end using either
2175 // size() if this obj is completely contained in the current region.
2176 HeapWord* next_region_start = region_start + ParallelCompactData::RegionSize;
2177 HeapWord* partial_obj_start = (next_region_start >= src_space_top)
2178 ? nullptr
2179 : sd.addr_to_region_ptr(next_region_start)->partial_obj_addr();
2180 // This obj extends to next region iff partial_obj_addr of the *next*
2181 // region is the same as obj-start.
2182 if (partial_obj_start == obj_start) {
2183 // This obj extends to next region.
2184 obj_end = partial_obj_end(next_region_start);
2185 } else {
2186 // Completely contained in this region; safe to use size().
2187 obj_end = obj_start + cast_to_oop(obj_start)->size();
2188 }
2189 } else {
2190 // This obj extends to current region.
2191 obj_end = partial_obj_end(region_start);
2192 }
2193 size_t partial_obj_size = pointer_delta(obj_end, closure.source());
2194 closure.copy_partial_obj(partial_obj_size);
2195 }
2196
2197 if (closure.is_full()) {
2198 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2199 closure.complete_region(dest_addr, region_ptr);
2200 return;
2201 }
2202
2203 // Finished copying without using up the current destination-region
2204 HeapWord* const end_addr = sd.region_align_down(closure.source());
2205 if (sd.region_align_down(old_src_addr) != end_addr) {
2206 assert(sd.region_align_up(old_src_addr) == end_addr, "only one region");
2207 // The partial object was copied from more than one source region.
2208 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2209
2210 // Move to the next source region, possibly switching spaces as well. All
2211 // args except end_addr may be modified.
2212 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2213 }
2214 }
2215
2216 // Handle the rest obj-by-obj, where we know obj-start.
2217 do {
2218 HeapWord* cur_addr = closure.source();
2219 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2220 src_space_top);
2221 // To handle the case where the final obj in source region extends to next region.
2222 HeapWord* final_obj_start = (end_addr == src_space_top)
2223 ? nullptr
2224 : sd.addr_to_region_ptr(end_addr)->partial_obj_addr();
2225 // Apply closure on objs inside [cur_addr, end_addr)
2226 do {
2227 cur_addr = bitmap->find_obj_beg(cur_addr, end_addr);
2228 if (cur_addr == end_addr) {
2229 break;
2230 }
2231 size_t obj_size;
2232 if (final_obj_start == cur_addr) {
2233 obj_size = pointer_delta(partial_obj_end(end_addr), cur_addr);
2234 } else {
2235 // This obj doesn't extend into next region; size() is safe to use.
2236 obj_size = cast_to_oop(cur_addr)->size();
2237 }
2238 closure.do_addr(cur_addr, obj_size);
2239 cur_addr += obj_size;
2240 } while (cur_addr < end_addr && !closure.is_full());
2241
2242 if (closure.is_full()) {
2243 decrement_destination_counts(cm, src_space_id, src_region_idx, closure.source());
2244 closure.complete_region(dest_addr, region_ptr);
2245 return;
2246 }
2247
2248 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2249
2250 // Move to the next source region, possibly switching spaces as well. All
2251 // args except end_addr may be modified.
2252 src_region_idx = next_src_region(closure, src_space_id, src_space_top, end_addr);
2253 } while (true);
2254 }
2255
2256 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
2257 {
2258 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2259 fill_region(cm, cl, region_idx);
2260 }
2261
2262 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
2263 {
2264 // Get a shadow region first
2265 ParallelCompactData& sd = summary_data();
2266 RegionData* const region_ptr = sd.region(region_idx);
2267 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
2268 // The InvalidShadow return value indicates the corresponding heap region is available,
2269 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
2270 // MoveAndUpdateShadowClosure to fill the acquired shadow region.
2271 if (shadow_region == ParCompactionManager::InvalidShadow) {
2272 MoveAndUpdateClosure cl(mark_bitmap(), region_idx);
2273 region_ptr->shadow_to_normal();
2274 return fill_region(cm, cl, region_idx);
2275 } else {
2276 MoveAndUpdateShadowClosure cl(mark_bitmap(), region_idx, shadow_region);
2277 return fill_region(cm, cl, region_idx);
2278 }
2279 }
2280
2281 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
2282 {
2283 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
2284 }
2285
2286 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx)
2287 {
2288 size_t next = cm->next_shadow_region();
2289 ParallelCompactData& sd = summary_data();
2290 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
2291 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2292
2293 while (next < old_new_top) {
2294 if (sd.region(next)->mark_shadow()) {
2295 region_idx = next;
2296 return true;
2297 }
2298 next = cm->move_next_shadow_region_by(active_gc_threads);
2299 }
2300
2301 return false;
2302 }
2303
2304 // The shadow region is an optimization to address region dependencies in full GC. The basic
2305 // idea is making more regions available by temporally storing their live objects in empty
2306 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
2307 // GC threads need not wait destination regions to be available before processing sources.
2308 //
2309 // A typical workflow would be:
2310 // After draining its own stack and failing to steal from others, a GC worker would pick an
2311 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
2312 // the shadow region by copying live objects from source regions of the unavailable one. Once
2313 // the unavailable region becomes available, the data in the shadow region will be copied back.
2314 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
2315 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
2316 {
2317 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2318
2319 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2320 SpaceInfo* const space_info = _space_info + id;
2321 MutableSpace* const space = space_info->space();
2322
2323 const size_t beg_region =
2324 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
2325 const size_t end_region =
2326 sd.addr_to_region_idx(sd.region_align_down(space->end()));
2327
2328 for (size_t cur = beg_region; cur < end_region; ++cur) {
2329 ParCompactionManager::push_shadow_region(cur);
2330 }
2331 }
2332
2333 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
2334 for (uint i = 0; i < parallel_gc_threads; i++) {
2335 ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i);
2336 cm->set_next_shadow_region(beg_region + i);
2337 }
2338 }
2339
2340 void MoveAndUpdateClosure::copy_partial_obj(size_t partial_obj_size)
2341 {
2342 size_t words = MIN2(partial_obj_size, words_remaining());
2343
2344 // This test is necessary; if omitted, the pointer updates to a partial object
2345 // that crosses the dense prefix boundary could be overwritten.
2346 if (source() != copy_destination()) {
2347 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2348 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2349 }
2350 update_state(words);
2351 }
2352
2353 void MoveAndUpdateClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2354 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
2355 region_ptr->set_completed();
2356 }
2357
2358 void MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
2359 assert(destination() != nullptr, "sanity");
2360 _source = addr;
2361
2362 // The start_array must be updated even if the object is not moving.
2363 if (_start_array != nullptr) {
2364 _start_array->update_for_block(destination(), destination() + words);
2365 }
2366
2367 // Avoid overflow
2368 words = MIN2(words, words_remaining());
2369 assert(words > 0, "inv");
2370
2371 if (copy_destination() != source()) {
2372 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2373 assert(source() != destination(), "inv");
2374 assert(FullGCForwarding::is_forwarded(cast_to_oop(source())), "inv");
2375 assert(FullGCForwarding::forwardee(cast_to_oop(source())) == cast_to_oop(destination()), "inv");
2376 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2377 cast_to_oop(copy_destination())->reinit_mark();
2378 }
2379
2380 update_state(words);
2381 }
2382
2383 void MoveAndUpdateShadowClosure::complete_region(HeapWord* dest_addr, PSParallelCompact::RegionData* region_ptr) {
2384 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
2385 // Record the shadow region index
2386 region_ptr->set_shadow_region(_shadow);
2387 // Mark the shadow region as filled to indicate the data is ready to be
2388 // copied back
2389 region_ptr->mark_filled();
2390 // Try to copy the content of the shadow region back to its corresponding
2391 // heap region if available; the GC thread that decreases the destination
2392 // count to zero will do the copying otherwise (see
2393 // PSParallelCompact::decrement_destination_counts).
2394 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
2395 region_ptr->set_completed();
2396 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
2397 ParCompactionManager::push_shadow_region_mt_safe(_shadow);
2398 }
2399 }