1 /*
2 * Copyright (c) 2005, 2024, 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 "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/javaClasses.inline.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "code/codeCache.hpp"
32 #include "compiler/oopMap.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/gcCause.hpp"
47 #include "gc/shared/gcHeapSummary.hpp"
48 #include "gc/shared/gcId.hpp"
49 #include "gc/shared/gcLocker.hpp"
50 #include "gc/shared/gcTimer.hpp"
51 #include "gc/shared/gcTrace.hpp"
52 #include "gc/shared/gcTraceTime.inline.hpp"
53 #include "gc/shared/isGCActiveMark.hpp"
54 #include "gc/shared/oopStorage.inline.hpp"
55 #include "gc/shared/oopStorageSet.inline.hpp"
56 #include "gc/shared/oopStorageSetParState.inline.hpp"
57 #include "gc/shared/referencePolicy.hpp"
58 #include "gc/shared/referenceProcessor.hpp"
59 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
60 #include "gc/shared/spaceDecorator.inline.hpp"
61 #include "gc/shared/taskTerminator.hpp"
62 #include "gc/shared/weakProcessor.inline.hpp"
63 #include "gc/shared/workerPolicy.hpp"
64 #include "gc/shared/workerThread.hpp"
65 #include "gc/shared/workerUtils.hpp"
66 #include "logging/log.hpp"
67 #include "memory/iterator.inline.hpp"
68 #include "memory/metaspaceUtils.hpp"
69 #include "memory/resourceArea.hpp"
70 #include "memory/universe.hpp"
71 #include "nmt/memTracker.hpp"
72 #include "oops/access.inline.hpp"
73 #include "oops/instanceClassLoaderKlass.inline.hpp"
74 #include "oops/instanceKlass.inline.hpp"
75 #include "oops/instanceMirrorKlass.inline.hpp"
76 #include "oops/methodData.hpp"
77 #include "oops/objArrayKlass.inline.hpp"
78 #include "oops/oop.inline.hpp"
79 #include "runtime/atomic.hpp"
80 #include "runtime/handles.inline.hpp"
81 #include "runtime/java.hpp"
82 #include "runtime/safepoint.hpp"
83 #include "runtime/threads.hpp"
84 #include "runtime/vmThread.hpp"
85 #include "services/memoryService.hpp"
86 #include "utilities/align.hpp"
87 #include "utilities/debug.hpp"
88 #include "utilities/events.hpp"
89 #include "utilities/formatBuffer.hpp"
90 #include "utilities/macros.hpp"
91 #include "utilities/stack.inline.hpp"
92 #if INCLUDE_JVMCI
93 #include "jvmci/jvmci.hpp"
94 #endif
95
96 #include <math.h>
97
98 // All sizes are in HeapWords.
99 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
100 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
101 const size_t ParallelCompactData::RegionSizeBytes =
102 RegionSize << LogHeapWordSize;
103 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
104 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
105 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
106
107 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
108 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
109 const size_t ParallelCompactData::BlockSizeBytes =
110 BlockSize << LogHeapWordSize;
111 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
112 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
113 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
114
115 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
116 const size_t ParallelCompactData::Log2BlocksPerRegion =
117 Log2RegionSize - Log2BlockSize;
118
119 const ParallelCompactData::RegionData::region_sz_t
120 ParallelCompactData::RegionData::dc_shift = 27;
121
122 const ParallelCompactData::RegionData::region_sz_t
123 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
124
125 const ParallelCompactData::RegionData::region_sz_t
126 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
127
128 const ParallelCompactData::RegionData::region_sz_t
129 ParallelCompactData::RegionData::los_mask = ~dc_mask;
130
131 const ParallelCompactData::RegionData::region_sz_t
132 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
133
134 const ParallelCompactData::RegionData::region_sz_t
135 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
136
137 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
138
139 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
140 ReferenceProcessor* PSParallelCompact::_ref_processor = nullptr;
141
142 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
143 HeapWord* destination)
144 {
145 assert(src_region_idx != 0, "invalid src_region_idx");
146 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
147 assert(destination != nullptr, "invalid destination argument");
148
149 _src_region_idx = src_region_idx;
150 _partial_obj_size = partial_obj_size;
151 _destination = destination;
152
153 // These fields may not be updated below, so make sure they're clear.
154 assert(_dest_region_addr == nullptr, "should have been cleared");
155 assert(_first_src_addr == nullptr, "should have been cleared");
156
157 // Determine the number of destination regions for the partial object.
158 HeapWord* const last_word = destination + partial_obj_size - 1;
159 const ParallelCompactData& sd = PSParallelCompact::summary_data();
160 HeapWord* const beg_region_addr = sd.region_align_down(destination);
161 HeapWord* const end_region_addr = sd.region_align_down(last_word);
162
163 if (beg_region_addr == end_region_addr) {
164 // One destination region.
165 _destination_count = 1;
166 if (end_region_addr == destination) {
167 // The destination falls on a region boundary, thus the first word of the
168 // partial object will be the first word copied to the destination region.
169 _dest_region_addr = end_region_addr;
170 _first_src_addr = sd.region_to_addr(src_region_idx);
171 }
172 } else {
173 // Two destination regions. When copied, the partial object will cross a
174 // destination region boundary, so a word somewhere within the partial
175 // object will be the first word copied to the second destination region.
176 _destination_count = 2;
177 _dest_region_addr = end_region_addr;
178 const size_t ofs = pointer_delta(end_region_addr, destination);
179 assert(ofs < _partial_obj_size, "sanity");
180 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
181 }
182 }
183
184 void SplitInfo::clear()
185 {
186 _src_region_idx = 0;
187 _partial_obj_size = 0;
188 _destination = nullptr;
189 _destination_count = 0;
190 _dest_region_addr = nullptr;
191 _first_src_addr = nullptr;
192 assert(!is_valid(), "sanity");
193 }
194
195 #ifdef ASSERT
196 void SplitInfo::verify_clear()
197 {
198 assert(_src_region_idx == 0, "not clear");
199 assert(_partial_obj_size == 0, "not clear");
200 assert(_destination == nullptr, "not clear");
201 assert(_destination_count == 0, "not clear");
202 assert(_dest_region_addr == nullptr, "not clear");
203 assert(_first_src_addr == nullptr, "not clear");
204 }
205 #endif // #ifdef ASSERT
206
207
208 void PSParallelCompact::print_on_error(outputStream* st) {
209 _mark_bitmap.print_on_error(st);
210 }
211
212 #ifndef PRODUCT
213 const char* PSParallelCompact::space_names[] = {
214 "old ", "eden", "from", "to "
215 };
216
217 void PSParallelCompact::print_region_ranges() {
218 if (!log_develop_is_enabled(Trace, gc, compaction)) {
219 return;
220 }
221 Log(gc, compaction) log;
222 ResourceMark rm;
223 LogStream ls(log.trace());
224 Universe::print_on(&ls);
225 log.trace("space bottom top end new_top");
226 log.trace("------ ---------- ---------- ---------- ----------");
227
228 for (unsigned int id = 0; id < last_space_id; ++id) {
229 const MutableSpace* space = _space_info[id].space();
230 log.trace("%u %s "
231 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
232 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
233 id, space_names[id],
234 summary_data().addr_to_region_idx(space->bottom()),
235 summary_data().addr_to_region_idx(space->top()),
236 summary_data().addr_to_region_idx(space->end()),
237 summary_data().addr_to_region_idx(_space_info[id].new_top()));
238 }
239 }
240
241 static void
242 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
243 {
244 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
245 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
246
247 ParallelCompactData& sd = PSParallelCompact::summary_data();
248 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
249 log_develop_trace(gc, compaction)(
250 REGION_IDX_FORMAT " "
251 REGION_IDX_FORMAT " " PTR_FORMAT " "
252 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
253 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
254 i, dci, p2i(c->destination()),
255 c->partial_obj_size(), c->live_obj_size(),
256 c->data_size(), c->source_region(), c->destination_count());
257
258 #undef REGION_IDX_FORMAT
259 #undef REGION_DATA_FORMAT
260 }
261
262 void
263 print_generic_summary_data(ParallelCompactData& summary_data,
264 HeapWord* const beg_addr,
265 HeapWord* const end_addr)
266 {
267 size_t total_words = 0;
268 size_t i = summary_data.addr_to_region_idx(beg_addr);
269 const size_t last = summary_data.addr_to_region_idx(end_addr);
270 HeapWord* pdest = 0;
271
272 while (i < last) {
273 ParallelCompactData::RegionData* c = summary_data.region(i);
274 if (c->data_size() != 0 || c->destination() != pdest) {
275 print_generic_summary_region(i, c);
276 total_words += c->data_size();
277 pdest = c->destination();
278 }
279 ++i;
280 }
281
282 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
283 }
284
285 void
286 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
287 HeapWord* const beg_addr,
288 HeapWord* const end_addr) {
289 ::print_generic_summary_data(summary_data,beg_addr, end_addr);
290 }
291
292 void
293 print_generic_summary_data(ParallelCompactData& summary_data,
294 SpaceInfo* space_info)
295 {
296 if (!log_develop_is_enabled(Trace, gc, compaction)) {
297 return;
298 }
299
300 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
301 const MutableSpace* space = space_info[id].space();
302 print_generic_summary_data(summary_data, space->bottom(),
303 MAX2(space->top(), space_info[id].new_top()));
304 }
305 }
306
307 static void
308 print_initial_summary_data(ParallelCompactData& summary_data,
309 const MutableSpace* space) {
310 if (space->top() == space->bottom()) {
311 return;
312 }
313
314 const size_t region_size = ParallelCompactData::RegionSize;
315 typedef ParallelCompactData::RegionData RegionData;
316 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
317 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
318 const RegionData* c = summary_data.region(end_region - 1);
319 HeapWord* end_addr = c->destination() + c->data_size();
320 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
321
322 // Print (and count) the full regions at the beginning of the space.
323 size_t full_region_count = 0;
324 size_t i = summary_data.addr_to_region_idx(space->bottom());
325 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
326 ParallelCompactData::RegionData* c = summary_data.region(i);
327 log_develop_trace(gc, compaction)(
328 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
329 i, p2i(c->destination()),
330 c->partial_obj_size(), c->live_obj_size(),
331 c->data_size(), c->source_region(), c->destination_count());
332 ++full_region_count;
333 ++i;
334 }
335
336 size_t live_to_right = live_in_space - full_region_count * region_size;
337
338 double max_reclaimed_ratio = 0.0;
339 size_t max_reclaimed_ratio_region = 0;
340 size_t max_dead_to_right = 0;
341 size_t max_live_to_right = 0;
342
343 // Print the 'reclaimed ratio' for regions while there is something live in
344 // the region or to the right of it. The remaining regions are empty (and
345 // uninteresting), and computing the ratio will result in division by 0.
346 while (i < end_region && live_to_right > 0) {
347 c = summary_data.region(i);
348 HeapWord* const region_addr = summary_data.region_to_addr(i);
349 const size_t used_to_right = pointer_delta(space->top(), region_addr);
350 const size_t dead_to_right = used_to_right - live_to_right;
351 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
352
353 if (reclaimed_ratio > max_reclaimed_ratio) {
354 max_reclaimed_ratio = reclaimed_ratio;
355 max_reclaimed_ratio_region = i;
356 max_dead_to_right = dead_to_right;
357 max_live_to_right = live_to_right;
358 }
359
360 ParallelCompactData::RegionData* c = summary_data.region(i);
361 log_develop_trace(gc, compaction)(
362 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
363 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
364 i, p2i(c->destination()),
365 c->partial_obj_size(), c->live_obj_size(),
366 c->data_size(), c->source_region(), c->destination_count(),
367 reclaimed_ratio, dead_to_right, live_to_right);
368
369
370 live_to_right -= c->data_size();
371 ++i;
372 }
373
374 // Any remaining regions are empty. Print one more if there is one.
375 if (i < end_region) {
376 ParallelCompactData::RegionData* c = summary_data.region(i);
377 log_develop_trace(gc, compaction)(
378 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
379 i, p2i(c->destination()),
380 c->partial_obj_size(), c->live_obj_size(),
381 c->data_size(), c->source_region(), c->destination_count());
382 }
383
384 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
385 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
386 }
387
388 static void
389 print_initial_summary_data(ParallelCompactData& summary_data,
390 SpaceInfo* space_info) {
391 if (!log_develop_is_enabled(Trace, gc, compaction)) {
392 return;
393 }
394
395 unsigned int id = PSParallelCompact::old_space_id;
396 const MutableSpace* space;
397 do {
398 space = space_info[id].space();
399 print_initial_summary_data(summary_data, space);
400 } while (++id < PSParallelCompact::eden_space_id);
401
402 do {
403 space = space_info[id].space();
404 print_generic_summary_data(summary_data, space->bottom(), space->top());
405 } while (++id < PSParallelCompact::last_space_id);
406 }
407 #endif // #ifndef PRODUCT
408
409 ParallelCompactData::ParallelCompactData() :
410 _heap_start(nullptr),
411 DEBUG_ONLY(_heap_end(nullptr) COMMA)
412 _region_vspace(nullptr),
413 _reserved_byte_size(0),
414 _region_data(nullptr),
415 _region_count(0),
416 _block_vspace(nullptr),
417 _block_data(nullptr),
418 _block_count(0) {}
419
420 bool ParallelCompactData::initialize(MemRegion reserved_heap)
421 {
422 _heap_start = reserved_heap.start();
423 const size_t heap_size = reserved_heap.word_size();
424 DEBUG_ONLY(_heap_end = _heap_start + heap_size;)
425
426 assert(region_align_down(_heap_start) == _heap_start,
427 "region start not aligned");
428
429 bool result = initialize_region_data(heap_size) && initialize_block_data();
430 return result;
431 }
432
433 PSVirtualSpace*
434 ParallelCompactData::create_vspace(size_t count, size_t element_size)
435 {
436 const size_t raw_bytes = count * element_size;
437 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
438 const size_t granularity = os::vm_allocation_granularity();
439 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
440
441 const size_t rs_align = page_sz == os::vm_page_size() ? 0 :
442 MAX2(page_sz, granularity);
443 ReservedSpace rs(_reserved_byte_size, rs_align, page_sz);
444 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, rs.base(),
445 rs.size(), page_sz);
446
447 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
448
449 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
450 if (vspace != 0) {
451 if (vspace->expand_by(_reserved_byte_size)) {
452 return vspace;
453 }
454 delete vspace;
455 // Release memory reserved in the space.
456 rs.release();
457 }
458
459 return 0;
460 }
461
462 bool ParallelCompactData::initialize_region_data(size_t heap_size)
463 {
464 assert(is_aligned(heap_size, RegionSize), "precondition");
465
466 const size_t count = heap_size >> Log2RegionSize;
467 _region_vspace = create_vspace(count, sizeof(RegionData));
468 if (_region_vspace != 0) {
469 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
470 _region_count = count;
471 return true;
472 }
473 return false;
474 }
475
476 bool ParallelCompactData::initialize_block_data()
477 {
478 assert(_region_count != 0, "region data must be initialized first");
479 const size_t count = _region_count << Log2BlocksPerRegion;
480 _block_vspace = create_vspace(count, sizeof(BlockData));
481 if (_block_vspace != 0) {
482 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
483 _block_count = count;
484 return true;
485 }
486 return false;
487 }
488
489 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
490 assert(beg_region <= _region_count, "beg_region out of range");
491 assert(end_region <= _region_count, "end_region out of range");
492 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
493
494 const size_t region_cnt = end_region - beg_region;
495 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
496
497 const size_t beg_block = beg_region * BlocksPerRegion;
498 const size_t block_cnt = region_cnt * BlocksPerRegion;
499 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
500 }
501
502 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
503 {
504 const RegionData* cur_cp = region(region_idx);
505 const RegionData* const end_cp = region(region_count() - 1);
506
507 HeapWord* result = region_to_addr(region_idx);
508 if (cur_cp < end_cp) {
509 do {
510 result += cur_cp->partial_obj_size();
511 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
512 }
513 return result;
514 }
515
516 void
517 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
518 {
519 assert(is_region_aligned(beg), "not RegionSize aligned");
520 assert(is_region_aligned(end), "not RegionSize aligned");
521
522 size_t cur_region = addr_to_region_idx(beg);
523 const size_t end_region = addr_to_region_idx(end);
524 HeapWord* addr = beg;
525 while (cur_region < end_region) {
526 _region_data[cur_region].set_destination(addr);
527 _region_data[cur_region].set_destination_count(0);
528 _region_data[cur_region].set_source_region(cur_region);
529
530 // Update live_obj_size so the region appears completely full.
531 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
532 _region_data[cur_region].set_live_obj_size(live_size);
533
534 ++cur_region;
535 addr += RegionSize;
536 }
537 }
538
539 // Find the point at which a space can be split and, if necessary, record the
540 // split point.
541 //
542 // If the current src region (which overflowed the destination space) doesn't
543 // have a partial object, the split point is at the beginning of the current src
544 // region (an "easy" split, no extra bookkeeping required).
545 //
546 // If the current src region has a partial object, the split point is in the
547 // region where that partial object starts (call it the split_region). If
548 // split_region has a partial object, then the split point is just after that
549 // partial object (a "hard" split where we have to record the split data and
550 // zero the partial_obj_size field). With a "hard" split, we know that the
551 // partial_obj ends within split_region because the partial object that caused
552 // the overflow starts in split_region. If split_region doesn't have a partial
553 // obj, then the split is at the beginning of split_region (another "easy"
554 // split).
555 HeapWord*
556 ParallelCompactData::summarize_split_space(size_t src_region,
557 SplitInfo& split_info,
558 HeapWord* destination,
559 HeapWord* target_end,
560 HeapWord** target_next)
561 {
562 assert(destination <= target_end, "sanity");
563 assert(destination + _region_data[src_region].data_size() > target_end,
564 "region should not fit into target space");
565 assert(is_region_aligned(target_end), "sanity");
566
567 size_t split_region = src_region;
568 HeapWord* split_destination = destination;
569 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
570
571 if (destination + partial_obj_size > target_end) {
572 // The split point is just after the partial object (if any) in the
573 // src_region that contains the start of the object that overflowed the
574 // destination space.
575 //
576 // Find the start of the "overflow" object and set split_region to the
577 // region containing it.
578 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
579 split_region = addr_to_region_idx(overflow_obj);
580
581 // Clear the source_region field of all destination regions whose first word
582 // came from data after the split point (a non-null source_region field
583 // implies a region must be filled).
584 //
585 // An alternative to the simple loop below: clear during post_compact(),
586 // which uses memcpy instead of individual stores, and is easy to
587 // parallelize. (The downside is that it clears the entire RegionData
588 // object as opposed to just one field.)
589 //
590 // post_compact() would have to clear the summary data up to the highest
591 // address that was written during the summary phase, which would be
592 //
593 // max(top, max(new_top, clear_top))
594 //
595 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
596 // to target_end.
597 const RegionData* const sr = region(split_region);
598 const size_t beg_idx =
599 addr_to_region_idx(region_align_up(sr->destination() +
600 sr->partial_obj_size()));
601 const size_t end_idx = addr_to_region_idx(target_end);
602
603 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
604 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
605 _region_data[idx].set_source_region(0);
606 }
607
608 // Set split_destination and partial_obj_size to reflect the split region.
609 split_destination = sr->destination();
610 partial_obj_size = sr->partial_obj_size();
611 }
612
613 // The split is recorded only if a partial object extends onto the region.
614 if (partial_obj_size != 0) {
615 _region_data[split_region].set_partial_obj_size(0);
616 split_info.record(split_region, partial_obj_size, split_destination);
617 }
618
619 // Setup the continuation addresses.
620 *target_next = split_destination + partial_obj_size;
621 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
622
623 if (log_develop_is_enabled(Trace, gc, compaction)) {
624 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
625 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
626 split_type, p2i(source_next), split_region, partial_obj_size);
627 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
628 split_type, p2i(split_destination),
629 addr_to_region_idx(split_destination),
630 p2i(*target_next));
631
632 if (partial_obj_size != 0) {
633 HeapWord* const po_beg = split_info.destination();
634 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
635 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
636 split_type,
637 p2i(po_beg), addr_to_region_idx(po_beg),
638 p2i(po_end), addr_to_region_idx(po_end));
639 }
640 }
641
642 return source_next;
643 }
644
645 bool ParallelCompactData::summarize(SplitInfo& split_info,
646 HeapWord* source_beg, HeapWord* source_end,
647 HeapWord** source_next,
648 HeapWord* target_beg, HeapWord* target_end,
649 HeapWord** target_next)
650 {
651 HeapWord* const source_next_val = source_next == nullptr ? nullptr : *source_next;
652 log_develop_trace(gc, compaction)(
653 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
654 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
655 p2i(source_beg), p2i(source_end), p2i(source_next_val),
656 p2i(target_beg), p2i(target_end), p2i(*target_next));
657
658 size_t cur_region = addr_to_region_idx(source_beg);
659 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
660
661 HeapWord *dest_addr = target_beg;
662 while (cur_region < end_region) {
663 // The destination must be set even if the region has no data.
664 _region_data[cur_region].set_destination(dest_addr);
665
666 size_t words = _region_data[cur_region].data_size();
667 if (words > 0) {
668 // If cur_region does not fit entirely into the target space, find a point
669 // at which the source space can be 'split' so that part is copied to the
670 // target space and the rest is copied elsewhere.
671 if (dest_addr + words > target_end) {
672 assert(source_next != nullptr, "source_next is null when splitting");
673 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
674 target_end, target_next);
675 return false;
676 }
677
678 // Compute the destination_count for cur_region, and if necessary, update
679 // source_region for a destination region. The source_region field is
680 // updated if cur_region is the first (left-most) region to be copied to a
681 // destination region.
682 //
683 // The destination_count calculation is a bit subtle. A region that has
684 // data that compacts into itself does not count itself as a destination.
685 // This maintains the invariant that a zero count means the region is
686 // available and can be claimed and then filled.
687 uint destination_count = 0;
688 if (split_info.is_split(cur_region)) {
689 // The current region has been split: the partial object will be copied
690 // to one destination space and the remaining data will be copied to
691 // another destination space. Adjust the initial destination_count and,
692 // if necessary, set the source_region field if the partial object will
693 // cross a destination region boundary.
694 destination_count = split_info.destination_count();
695 if (destination_count == 2) {
696 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
697 _region_data[dest_idx].set_source_region(cur_region);
698 }
699 }
700
701 HeapWord* const last_addr = dest_addr + words - 1;
702 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
703 const size_t dest_region_2 = addr_to_region_idx(last_addr);
704
705 // Initially assume that the destination regions will be the same and
706 // adjust the value below if necessary. Under this assumption, if
707 // cur_region == dest_region_2, then cur_region will be compacted
708 // completely into itself.
709 destination_count += cur_region == dest_region_2 ? 0 : 1;
710 if (dest_region_1 != dest_region_2) {
711 // Destination regions differ; adjust destination_count.
712 destination_count += 1;
713 // Data from cur_region will be copied to the start of dest_region_2.
714 _region_data[dest_region_2].set_source_region(cur_region);
715 } else if (is_region_aligned(dest_addr)) {
716 // Data from cur_region will be copied to the start of the destination
717 // region.
718 _region_data[dest_region_1].set_source_region(cur_region);
719 }
720
721 _region_data[cur_region].set_destination_count(destination_count);
722 dest_addr += words;
723 }
724
725 ++cur_region;
726 }
727
728 *target_next = dest_addr;
729 return true;
730 }
731
732 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) const {
733 assert(addr != nullptr, "Should detect null oop earlier");
734 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
735 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
736
737 // Region covering the object.
738 RegionData* const region_ptr = addr_to_region_ptr(addr);
739 HeapWord* result = region_ptr->destination();
740
741 // If the entire Region is live, the new location is region->destination + the
742 // offset of the object within in the Region.
743
744 // Run some performance tests to determine if this special case pays off. It
745 // is worth it for pointers into the dense prefix. If the optimization to
746 // avoid pointer updates in regions that only point to the dense prefix is
747 // ever implemented, this should be revisited.
748 if (region_ptr->data_size() == RegionSize) {
749 result += region_offset(addr);
750 return result;
751 }
752
753 // Otherwise, the new location is region->destination + block offset + the
754 // number of live words in the Block that are (a) to the left of addr and (b)
755 // due to objects that start in the Block.
756
757 // Fill in the block table if necessary. This is unsynchronized, so multiple
758 // threads may fill the block table for a region (harmless, since it is
759 // idempotent).
760 if (!region_ptr->blocks_filled()) {
761 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
762 region_ptr->set_blocks_filled();
763 }
764
765 HeapWord* const search_start = block_align_down(addr);
766 const size_t block_offset = addr_to_block_ptr(addr)->offset();
767
768 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
769 const size_t live = bitmap->live_words_in_range(cm, search_start, cast_to_oop(addr));
770 result += block_offset + live;
771 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
772 return result;
773 }
774
775 #ifdef ASSERT
776 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
777 {
778 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
779 const size_t* const end = (const size_t*)vspace->committed_high_addr();
780 for (const size_t* p = beg; p < end; ++p) {
781 assert(*p == 0, "not zero");
782 }
783 }
784
785 void ParallelCompactData::verify_clear()
786 {
787 verify_clear(_region_vspace);
788 verify_clear(_block_vspace);
789 }
790 #endif // #ifdef ASSERT
791
792 STWGCTimer PSParallelCompact::_gc_timer;
793 ParallelOldTracer PSParallelCompact::_gc_tracer;
794 elapsedTimer PSParallelCompact::_accumulated_time;
795 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
796 CollectorCounters* PSParallelCompact::_counters = nullptr;
797 ParMarkBitMap PSParallelCompact::_mark_bitmap;
798 ParallelCompactData PSParallelCompact::_summary_data;
799
800 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
801
802 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
803
804 void PSParallelCompact::post_initialize() {
805 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
806 _span_based_discoverer.set_span(heap->reserved_region());
807 _ref_processor =
808 new ReferenceProcessor(&_span_based_discoverer,
809 ParallelGCThreads, // mt processing degree
810 ParallelGCThreads, // mt discovery degree
811 false, // concurrent_discovery
812 &_is_alive_closure); // non-header is alive closure
813
814 _counters = new CollectorCounters("Parallel full collection pauses", 1);
815
816 // Initialize static fields in ParCompactionManager.
817 ParCompactionManager::initialize(mark_bitmap());
818 }
819
820 bool PSParallelCompact::initialize_aux_data() {
821 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
822 MemRegion mr = heap->reserved_region();
823 assert(mr.byte_size() != 0, "heap should be reserved");
824
825 initialize_space_info();
826
827 if (!_mark_bitmap.initialize(mr)) {
828 vm_shutdown_during_initialization(
829 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
830 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
831 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
832 return false;
833 }
834
835 if (!_summary_data.initialize(mr)) {
836 vm_shutdown_during_initialization(
837 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
838 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
839 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
840 return false;
841 }
842
843 return true;
844 }
845
846 void PSParallelCompact::initialize_space_info()
847 {
848 memset(&_space_info, 0, sizeof(_space_info));
849
850 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
851 PSYoungGen* young_gen = heap->young_gen();
852
853 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
854 _space_info[eden_space_id].set_space(young_gen->eden_space());
855 _space_info[from_space_id].set_space(young_gen->from_space());
856 _space_info[to_space_id].set_space(young_gen->to_space());
857
858 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
859 }
860
861 void
862 PSParallelCompact::clear_data_covering_space(SpaceId id)
863 {
864 // At this point, top is the value before GC, new_top() is the value that will
865 // be set at the end of GC. The marking bitmap is cleared to top; nothing
866 // should be marked above top. The summary data is cleared to the larger of
867 // top & new_top.
868 MutableSpace* const space = _space_info[id].space();
869 HeapWord* const bot = space->bottom();
870 HeapWord* const top = space->top();
871 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
872
873 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
874 const idx_t end_bit = _mark_bitmap.addr_to_bit(top);
875 _mark_bitmap.clear_range(beg_bit, end_bit);
876
877 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
878 const size_t end_region =
879 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
880 _summary_data.clear_range(beg_region, end_region);
881
882 // Clear the data used to 'split' regions.
883 SplitInfo& split_info = _space_info[id].split_info();
884 if (split_info.is_valid()) {
885 split_info.clear();
886 }
887 DEBUG_ONLY(split_info.verify_clear();)
888 }
889
890 void PSParallelCompact::pre_compact()
891 {
892 // Update the from & to space pointers in space_info, since they are swapped
893 // at each young gen gc. Do the update unconditionally (even though a
894 // promotion failure does not swap spaces) because an unknown number of young
895 // collections will have swapped the spaces an unknown number of times.
896 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
897 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
898 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
899 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
900
901 // Increment the invocation count
902 heap->increment_total_collections(true);
903
904 CodeCache::on_gc_marking_cycle_start();
905
906 heap->print_heap_before_gc();
907 heap->trace_heap_before_gc(&_gc_tracer);
908
909 // Fill in TLABs
910 heap->ensure_parsability(true); // retire TLABs
911
912 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
913 Universe::verify("Before GC");
914 }
915
916 DEBUG_ONLY(mark_bitmap()->verify_clear();)
917 DEBUG_ONLY(summary_data().verify_clear();)
918
919 ParCompactionManager::reset_all_bitmap_query_caches();
920 }
921
922 void PSParallelCompact::post_compact()
923 {
924 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
925 ParCompactionManager::remove_all_shadow_regions();
926
927 CodeCache::on_gc_marking_cycle_finish();
928 CodeCache::arm_all_nmethods();
929
930 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
931 // Clear the marking bitmap, summary data and split info.
932 clear_data_covering_space(SpaceId(id));
933 // Update top(). Must be done after clearing the bitmap and summary data.
934 _space_info[id].publish_new_top();
935 }
936
937 ParCompactionManager::flush_all_string_dedup_requests();
938
939 MutableSpace* const eden_space = _space_info[eden_space_id].space();
940 MutableSpace* const from_space = _space_info[from_space_id].space();
941 MutableSpace* const to_space = _space_info[to_space_id].space();
942
943 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
944 bool eden_empty = eden_space->is_empty();
945
946 // Update heap occupancy information which is used as input to the soft ref
947 // clearing policy at the next gc.
948 Universe::heap()->update_capacity_and_used_at_gc();
949
950 bool young_gen_empty = eden_empty && from_space->is_empty() &&
951 to_space->is_empty();
952
953 PSCardTable* ct = heap->card_table();
954 MemRegion old_mr = heap->old_gen()->committed();
955 if (young_gen_empty) {
956 ct->clear_MemRegion(old_mr);
957 } else {
958 ct->dirty_MemRegion(old_mr);
959 }
960
961 {
962 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
963 GCTraceTime(Debug, gc, phases) t("Purge Class Loader Data", gc_timer());
964 ClassLoaderDataGraph::purge(true /* at_safepoint */);
965 DEBUG_ONLY(MetaspaceUtils::verify();)
966 }
967
968 // Need to clear claim bits for the next mark.
969 ClassLoaderDataGraph::clear_claimed_marks();
970
971 heap->prune_scavengable_nmethods();
972
973 #if COMPILER2_OR_JVMCI
974 DerivedPointerTable::update_pointers();
975 #endif
976
977 if (ZapUnusedHeapArea) {
978 heap->gen_mangle_unused_area();
979 }
980
981 // Signal that we have completed a visit to all live objects.
982 Universe::heap()->record_whole_heap_examined_timestamp();
983 }
984
985 ParallelCompactData::RegionData*
986 PSParallelCompact::first_dead_space_region(const RegionData* beg,
987 const RegionData* end)
988 {
989 const size_t region_size = ParallelCompactData::RegionSize;
990 ParallelCompactData& sd = summary_data();
991 size_t left = sd.region(beg);
992 size_t right = end > beg ? sd.region(end) - 1 : left;
993
994 // Binary search.
995 while (left < right) {
996 // Equivalent to (left + right) / 2, but does not overflow.
997 const size_t middle = left + (right - left) / 2;
998 RegionData* const middle_ptr = sd.region(middle);
999 HeapWord* const dest = middle_ptr->destination();
1000 HeapWord* const addr = sd.region_to_addr(middle);
1001 assert(dest != nullptr, "sanity");
1002 assert(dest <= addr, "must move left");
1003
1004 if (middle > left && dest < addr) {
1005 right = middle - 1;
1006 } else if (middle < right && middle_ptr->data_size() == region_size) {
1007 left = middle + 1;
1008 } else {
1009 return middle_ptr;
1010 }
1011 }
1012 return sd.region(left);
1013 }
1014
1015 // Return the address of the end of the dense prefix, a.k.a. the start of the
1016 // compacted region. The address is always on a region boundary.
1017 //
1018 // Completely full regions at the left are skipped, since no compaction can
1019 // occur in those regions. Then the maximum amount of dead wood to allow is
1020 // computed, based on the density (amount live / capacity) of the generation;
1021 // the region with approximately that amount of dead space to the left is
1022 // identified as the limit region. Regions between the last completely full
1023 // region and the limit region are scanned and the one that has the best
1024 // (maximum) reclaimed_ratio() is selected.
1025 HeapWord*
1026 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1027 bool maximum_compaction)
1028 {
1029 const size_t region_size = ParallelCompactData::RegionSize;
1030 const ParallelCompactData& sd = summary_data();
1031
1032 const MutableSpace* const space = _space_info[id].space();
1033 HeapWord* const top = space->top();
1034 HeapWord* const top_aligned_up = sd.region_align_up(top);
1035 HeapWord* const new_top = _space_info[id].new_top();
1036 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1037 HeapWord* const bottom = space->bottom();
1038 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1039 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1040 const RegionData* const new_top_cp =
1041 sd.addr_to_region_ptr(new_top_aligned_up);
1042
1043 // Skip full regions at the beginning of the space--they are necessarily part
1044 // of the dense prefix.
1045 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1046 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1047 space->is_empty(), "no dead space allowed to the left");
1048 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1049 "region must have dead space");
1050
1051 // The gc number is saved whenever a maximum compaction is done, and used to
1052 // determine when the maximum compaction interval has expired. This avoids
1053 // successive max compactions for different reasons.
1054 const uint total_invocations = ParallelScavengeHeap::heap()->total_full_collections();
1055 assert(total_invocations >= _maximum_compaction_gc_num, "sanity");
1056 const size_t gcs_since_max = total_invocations - _maximum_compaction_gc_num;
1057 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1058 total_invocations == HeapFirstMaximumCompactionCount;
1059 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1060 _maximum_compaction_gc_num = total_invocations;
1061 return sd.region_to_addr(full_cp);
1062 }
1063
1064 // Iteration starts with the region *after* the full-region-prefix-end.
1065 const RegionData* const start_region = full_cp;
1066 // If final region is not full, iteration stops before that region,
1067 // because fill_dense_prefix_end assumes that prefix_end <= top.
1068 const RegionData* const end_region = sd.addr_to_region_ptr(space->top());
1069 assert(start_region <= end_region, "inv");
1070
1071 size_t max_waste = space->capacity_in_words() * (MarkSweepDeadRatio / 100.0);
1072 const RegionData* cur_region = start_region;
1073 for (/* empty */; cur_region < end_region; ++cur_region) {
1074 assert(region_size >= cur_region->data_size(), "inv");
1075 size_t dead_size = region_size - cur_region->data_size();
1076 if (max_waste < dead_size) {
1077 break;
1078 }
1079 max_waste -= dead_size;
1080 }
1081
1082 HeapWord* const prefix_end = sd.region_to_addr(cur_region);
1083 assert(sd.is_region_aligned(prefix_end), "postcondition");
1084 assert(prefix_end >= sd.region_to_addr(full_cp), "in-range");
1085 assert(prefix_end <= space->top(), "in-range");
1086 return prefix_end;
1087 }
1088
1089 void PSParallelCompact::summarize_spaces_quick()
1090 {
1091 for (unsigned int i = 0; i < last_space_id; ++i) {
1092 const MutableSpace* space = _space_info[i].space();
1093 HeapWord** nta = _space_info[i].new_top_addr();
1094 bool result = _summary_data.summarize(_space_info[i].split_info(),
1095 space->bottom(), space->top(), nullptr,
1096 space->bottom(), space->end(), nta);
1097 assert(result, "space must fit into itself");
1098 _space_info[i].set_dense_prefix(space->bottom());
1099 }
1100 }
1101
1102 void PSParallelCompact::fill_dense_prefix_end(SpaceId id) {
1103 // Comparing two sizes to decide if filling is required:
1104 //
1105 // The size of the filler (min-obj-size) is 2 heap words with the default
1106 // MinObjAlignment, since both markword and klass take 1 heap word.
1107 //
1108 // The size of the gap (if any) right before dense-prefix-end is
1109 // MinObjAlignment.
1110 //
1111 // Need to fill in the gap only if it's smaller than min-obj-size, and the
1112 // filler obj will extend to next region.
1113
1114 // Note: If min-fill-size decreases to 1, this whole method becomes redundant.
1115 if (UseCompactObjectHeaders) {
1116 // The gap is always equal to min-fill-size, so nothing to do.
1117 return;
1118 }
1119 assert(CollectedHeap::min_fill_size() >= 2, "inv");
1120 #ifndef _LP64
1121 // In 32-bit system, each heap word is 4 bytes, so MinObjAlignment == 2.
1122 // The gap is always equal to min-fill-size, so nothing to do.
1123 return;
1124 #endif
1125 if (MinObjAlignment > 1) {
1126 return;
1127 }
1128 assert(CollectedHeap::min_fill_size() == 2, "inv");
1129 HeapWord* const dense_prefix_end = dense_prefix(id);
1130 RegionData* const region_after_dense_prefix = _summary_data.addr_to_region_ptr(dense_prefix_end);
1131 idx_t const dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1132
1133 if (region_after_dense_prefix->partial_obj_size() != 0 ||
1134 _mark_bitmap.is_obj_beg(dense_prefix_bit)) {
1135 // The region after the dense prefix starts with live bytes.
1136 return;
1137 }
1138
1139 if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1140 // There is exactly one heap word gap right before the dense prefix end, so we need a filler object.
1141 // The filler object will extend into the region after the last dense prefix region.
1142 const size_t obj_len = 2; // min-fill-size
1143 HeapWord* const obj_beg = dense_prefix_end - 1;
1144 CollectedHeap::fill_with_object(obj_beg, obj_len);
1145 _mark_bitmap.mark_obj(obj_beg, obj_len);
1146 _summary_data.addr_to_region_ptr(obj_beg)->add_live_obj(1);
1147 region_after_dense_prefix->set_partial_obj_size(1);
1148 region_after_dense_prefix->set_partial_obj_addr(obj_beg);
1149 assert(start_array(id) != nullptr, "sanity");
1150 start_array(id)->update_for_block(obj_beg, obj_beg + obj_len);
1151 }
1152 }
1153
1154 void
1155 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1156 {
1157 assert(id < last_space_id, "id out of range");
1158 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1159 "should have been reset in summarize_spaces_quick()");
1160
1161 const MutableSpace* space = _space_info[id].space();
1162 if (_space_info[id].new_top() != space->bottom()) {
1163 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1164 _space_info[id].set_dense_prefix(dense_prefix_end);
1165
1166 // Recompute the summary data, taking into account the dense prefix. If
1167 // every last byte will be reclaimed, then the existing summary data which
1168 // compacts everything can be left in place.
1169 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1170 // If dead space crosses the dense prefix boundary, it is (at least
1171 // partially) filled with a dummy object, marked live and added to the
1172 // summary data. This simplifies the copy/update phase and must be done
1173 // before the final locations of objects are determined, to prevent
1174 // leaving a fragment of dead space that is too small to fill.
1175 fill_dense_prefix_end(id);
1176
1177 // Compute the destination of each Region, and thus each object.
1178 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1179 _summary_data.summarize(_space_info[id].split_info(),
1180 dense_prefix_end, space->top(), nullptr,
1181 dense_prefix_end, space->end(),
1182 _space_info[id].new_top_addr());
1183 }
1184 }
1185
1186 if (log_develop_is_enabled(Trace, gc, compaction)) {
1187 const size_t region_size = ParallelCompactData::RegionSize;
1188 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1189 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1190 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1191 HeapWord* const new_top = _space_info[id].new_top();
1192 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1193 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1194 log_develop_trace(gc, compaction)(
1195 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1196 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1197 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1198 id, space->capacity_in_words(), p2i(dense_prefix_end),
1199 dp_region, dp_words / region_size,
1200 cr_words / region_size, p2i(new_top));
1201 }
1202 }
1203
1204 #ifndef PRODUCT
1205 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1206 HeapWord* dst_beg, HeapWord* dst_end,
1207 SpaceId src_space_id,
1208 HeapWord* src_beg, HeapWord* src_end)
1209 {
1210 log_develop_trace(gc, compaction)(
1211 "Summarizing %d [%s] into %d [%s]: "
1212 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1213 SIZE_FORMAT "-" SIZE_FORMAT " "
1214 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1215 SIZE_FORMAT "-" SIZE_FORMAT,
1216 src_space_id, space_names[src_space_id],
1217 dst_space_id, space_names[dst_space_id],
1218 p2i(src_beg), p2i(src_end),
1219 _summary_data.addr_to_region_idx(src_beg),
1220 _summary_data.addr_to_region_idx(src_end),
1221 p2i(dst_beg), p2i(dst_end),
1222 _summary_data.addr_to_region_idx(dst_beg),
1223 _summary_data.addr_to_region_idx(dst_end));
1224 }
1225 #endif // #ifndef PRODUCT
1226
1227 void PSParallelCompact::summary_phase(bool maximum_compaction)
1228 {
1229 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1230
1231 // Quick summarization of each space into itself, to see how much is live.
1232 summarize_spaces_quick();
1233
1234 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1235 NOT_PRODUCT(print_region_ranges());
1236 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1237
1238 // The amount of live data that will end up in old space (assuming it fits).
1239 size_t old_space_total_live = 0;
1240 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1241 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1242 _space_info[id].space()->bottom());
1243 }
1244
1245 MutableSpace* const old_space = _space_info[old_space_id].space();
1246 const size_t old_capacity = old_space->capacity_in_words();
1247 if (old_space_total_live > old_capacity) {
1248 // XXX - should also try to expand
1249 maximum_compaction = true;
1250 }
1251
1252 // Old generations.
1253 summarize_space(old_space_id, maximum_compaction);
1254
1255 // Summarize the remaining spaces in the young gen. The initial target space
1256 // is the old gen. If a space does not fit entirely into the target, then the
1257 // remainder is compacted into the space itself and that space becomes the new
1258 // target.
1259 SpaceId dst_space_id = old_space_id;
1260 HeapWord* dst_space_end = old_space->end();
1261 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1262 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1263 const MutableSpace* space = _space_info[id].space();
1264 const size_t live = pointer_delta(_space_info[id].new_top(),
1265 space->bottom());
1266 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1267
1268 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1269 SpaceId(id), space->bottom(), space->top());)
1270 if (live > 0 && live <= available) {
1271 // All the live data will fit.
1272 bool done = _summary_data.summarize(_space_info[id].split_info(),
1273 space->bottom(), space->top(),
1274 nullptr,
1275 *new_top_addr, dst_space_end,
1276 new_top_addr);
1277 assert(done, "space must fit into old gen");
1278
1279 // Reset the new_top value for the space.
1280 _space_info[id].set_new_top(space->bottom());
1281 } else if (live > 0) {
1282 // Attempt to fit part of the source space into the target space.
1283 HeapWord* next_src_addr = nullptr;
1284 bool done = _summary_data.summarize(_space_info[id].split_info(),
1285 space->bottom(), space->top(),
1286 &next_src_addr,
1287 *new_top_addr, dst_space_end,
1288 new_top_addr);
1289 assert(!done, "space should not fit into old gen");
1290 assert(next_src_addr != nullptr, "sanity");
1291
1292 // The source space becomes the new target, so the remainder is compacted
1293 // within the space itself.
1294 dst_space_id = SpaceId(id);
1295 dst_space_end = space->end();
1296 new_top_addr = _space_info[id].new_top_addr();
1297 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1298 space->bottom(), dst_space_end,
1299 SpaceId(id), next_src_addr, space->top());)
1300 done = _summary_data.summarize(_space_info[id].split_info(),
1301 next_src_addr, space->top(),
1302 nullptr,
1303 space->bottom(), dst_space_end,
1304 new_top_addr);
1305 assert(done, "space must fit when compacted into itself");
1306 assert(*new_top_addr <= space->top(), "usage should not grow");
1307 }
1308 }
1309
1310 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1311 NOT_PRODUCT(print_region_ranges());
1312 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1313 }
1314
1315 // This method should contain all heap-specific policy for invoking a full
1316 // collection. invoke_no_policy() will only attempt to compact the heap; it
1317 // will do nothing further. If we need to bail out for policy reasons, scavenge
1318 // before full gc, or any other specialized behavior, it needs to be added here.
1319 //
1320 // Note that this method should only be called from the vm_thread while at a
1321 // safepoint.
1322 //
1323 // Note that the all_soft_refs_clear flag in the soft ref policy
1324 // may be true because this method can be called without intervening
1325 // activity. For example when the heap space is tight and full measure
1326 // are being taken to free space.
1327 bool PSParallelCompact::invoke(bool maximum_heap_compaction) {
1328 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1329 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1330 "should be in vm thread");
1331
1332 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1333 assert(!heap->is_gc_active(), "not reentrant");
1334
1335 IsGCActiveMark mark;
1336
1337 if (ScavengeBeforeFullGC) {
1338 PSScavenge::invoke_no_policy();
1339 }
1340
1341 const bool clear_all_soft_refs =
1342 heap->soft_ref_policy()->should_clear_all_soft_refs();
1343
1344 return PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1345 maximum_heap_compaction);
1346 }
1347
1348 // This method contains no policy. You should probably
1349 // be calling invoke() instead.
1350 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1351 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1352 assert(ref_processor() != nullptr, "Sanity");
1353
1354 if (GCLocker::check_active_before_gc()) {
1355 return false;
1356 }
1357
1358 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1359
1360 GCIdMark gc_id_mark;
1361 _gc_timer.register_gc_start();
1362 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1363
1364 GCCause::Cause gc_cause = heap->gc_cause();
1365 PSYoungGen* young_gen = heap->young_gen();
1366 PSOldGen* old_gen = heap->old_gen();
1367 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1368
1369 // The scope of casr should end after code that can change
1370 // SoftRefPolicy::_should_clear_all_soft_refs.
1371 ClearedAllSoftRefs casr(maximum_heap_compaction,
1372 heap->soft_ref_policy());
1373
1374 if (ZapUnusedHeapArea) {
1375 // Save information needed to minimize mangling
1376 heap->record_gen_tops_before_GC();
1377 }
1378
1379 // Make sure data structures are sane, make the heap parsable, and do other
1380 // miscellaneous bookkeeping.
1381 pre_compact();
1382
1383 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
1384
1385 {
1386 const uint active_workers =
1387 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(),
1388 ParallelScavengeHeap::heap()->workers().active_workers(),
1389 Threads::number_of_non_daemon_threads());
1390 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers);
1391
1392 GCTraceCPUTime tcpu(&_gc_tracer);
1393 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause, true);
1394
1395 heap->pre_full_gc_dump(&_gc_timer);
1396
1397 TraceCollectorStats tcs(counters());
1398 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause, "end of major GC");
1399
1400 if (log_is_enabled(Debug, gc, heap, exit)) {
1401 accumulated_time()->start();
1402 }
1403
1404 // Let the size policy know we're starting
1405 size_policy->major_collection_begin();
1406
1407 #if COMPILER2_OR_JVMCI
1408 DerivedPointerTable::clear();
1409 #endif
1410
1411 ref_processor()->start_discovery(maximum_heap_compaction);
1412
1413 ClassUnloadingContext ctx(1 /* num_nmethod_unlink_workers */,
1414 false /* unregister_nmethods_during_purge */,
1415 false /* lock_nmethod_free_separately */);
1416
1417 marking_phase(&_gc_tracer);
1418
1419 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1420 && GCCause::is_user_requested_gc(gc_cause);
1421 summary_phase(maximum_heap_compaction || max_on_system_gc);
1422
1423 #if COMPILER2_OR_JVMCI
1424 assert(DerivedPointerTable::is_active(), "Sanity");
1425 DerivedPointerTable::set_active(false);
1426 #endif
1427
1428 // adjust_roots() updates Universe::_intArrayKlass which is
1429 // needed by the compaction for filling holes in the dense prefix.
1430 adjust_roots();
1431
1432 compact();
1433
1434 ParCompactionManager::verify_all_region_stack_empty();
1435
1436 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1437 // done before resizing.
1438 post_compact();
1439
1440 // Let the size policy know we're done
1441 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1442
1443 if (UseAdaptiveSizePolicy) {
1444 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1445 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1446 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1447
1448 // Don't check if the size_policy is ready here. Let
1449 // the size_policy check that internally.
1450 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1451 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1452 // Swap the survivor spaces if from_space is empty. The
1453 // resize_young_gen() called below is normally used after
1454 // a successful young GC and swapping of survivor spaces;
1455 // otherwise, it will fail to resize the young gen with
1456 // the current implementation.
1457 if (young_gen->from_space()->is_empty()) {
1458 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1459 young_gen->swap_spaces();
1460 }
1461
1462 // Calculate optimal free space amounts
1463 assert(young_gen->max_gen_size() >
1464 young_gen->from_space()->capacity_in_bytes() +
1465 young_gen->to_space()->capacity_in_bytes(),
1466 "Sizes of space in young gen are out-of-bounds");
1467
1468 size_t young_live = young_gen->used_in_bytes();
1469 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1470 size_t old_live = old_gen->used_in_bytes();
1471 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1472 size_t max_old_gen_size = old_gen->max_gen_size();
1473 size_t max_eden_size = young_gen->max_gen_size() -
1474 young_gen->from_space()->capacity_in_bytes() -
1475 young_gen->to_space()->capacity_in_bytes();
1476
1477 // Used for diagnostics
1478 size_policy->clear_generation_free_space_flags();
1479
1480 size_policy->compute_generations_free_space(young_live,
1481 eden_live,
1482 old_live,
1483 cur_eden,
1484 max_old_gen_size,
1485 max_eden_size,
1486 true /* full gc*/);
1487
1488 size_policy->check_gc_overhead_limit(eden_live,
1489 max_old_gen_size,
1490 max_eden_size,
1491 true /* full gc*/,
1492 gc_cause,
1493 heap->soft_ref_policy());
1494
1495 size_policy->decay_supplemental_growth(true /* full gc*/);
1496
1497 heap->resize_old_gen(
1498 size_policy->calculated_old_free_size_in_bytes());
1499
1500 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1501 size_policy->calculated_survivor_size_in_bytes());
1502 }
1503
1504 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1505 }
1506
1507 if (UsePerfData) {
1508 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1509 counters->update_counters();
1510 counters->update_old_capacity(old_gen->capacity_in_bytes());
1511 counters->update_young_capacity(young_gen->capacity_in_bytes());
1512 }
1513
1514 heap->resize_all_tlabs();
1515
1516 // Resize the metaspace capacity after a collection
1517 MetaspaceGC::compute_new_size();
1518
1519 if (log_is_enabled(Debug, gc, heap, exit)) {
1520 accumulated_time()->stop();
1521 }
1522
1523 heap->print_heap_change(pre_gc_values);
1524
1525 // Track memory usage and detect low memory
1526 MemoryService::track_memory_usage();
1527 heap->update_counters();
1528
1529 heap->post_full_gc_dump(&_gc_timer);
1530 }
1531
1532 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1533 Universe::verify("After GC");
1534 }
1535
1536 if (ZapUnusedHeapArea) {
1537 old_gen->object_space()->check_mangled_unused_area_complete();
1538 }
1539
1540 heap->print_heap_after_gc();
1541 heap->trace_heap_after_gc(&_gc_tracer);
1542
1543 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1544
1545 _gc_timer.register_gc_end();
1546
1547 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1548 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1549
1550 return true;
1551 }
1552
1553 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1554 private:
1555 uint _worker_id;
1556
1557 public:
1558 PCAddThreadRootsMarkingTaskClosure(uint worker_id) : _worker_id(worker_id) { }
1559 void do_thread(Thread* thread) {
1560 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
1561
1562 ResourceMark rm;
1563
1564 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(_worker_id);
1565
1566 PCMarkAndPushClosure mark_and_push_closure(cm);
1567 MarkingNMethodClosure mark_and_push_in_blobs(&mark_and_push_closure, !NMethodToOopClosure::FixRelocations, true /* keepalive nmethods */);
1568
1569 thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs);
1570
1571 // Do the real work
1572 cm->follow_marking_stacks();
1573 }
1574 };
1575
1576 void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
1577 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
1578
1579 ParCompactionManager* cm =
1580 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1581
1582 do {
1583 oop obj = nullptr;
1584 ObjArrayTask task;
1585 if (ParCompactionManager::steal_objarray(worker_id, task)) {
1586 cm->follow_array((objArrayOop)task.obj(), task.index());
1587 } else if (ParCompactionManager::steal(worker_id, obj)) {
1588 cm->follow_contents(obj);
1589 }
1590 cm->follow_marking_stacks();
1591 } while (!terminator.offer_termination());
1592 }
1593
1594 class MarkFromRootsTask : public WorkerTask {
1595 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
1596 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
1597 TaskTerminator _terminator;
1598 uint _active_workers;
1599
1600 public:
1601 MarkFromRootsTask(uint active_workers) :
1602 WorkerTask("MarkFromRootsTask"),
1603 _strong_roots_scope(active_workers),
1604 _terminator(active_workers, ParCompactionManager::oop_task_queues()),
1605 _active_workers(active_workers) {}
1606
1607 virtual void work(uint worker_id) {
1608 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1609 cm->create_marking_stats_cache();
1610 PCMarkAndPushClosure mark_and_push_closure(cm);
1611
1612 {
1613 CLDToOopClosure cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_stw_fullgc_mark);
1614 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
1615
1616 // Do the real work
1617 cm->follow_marking_stacks();
1618 }
1619
1620 PCAddThreadRootsMarkingTaskClosure closure(worker_id);
1621 Threads::possibly_parallel_threads_do(true /* is_par */, &closure);
1622
1623 // Mark from OopStorages
1624 {
1625 _oop_storage_set_par_state.oops_do(&mark_and_push_closure);
1626 // Do the real work
1627 cm->follow_marking_stacks();
1628 }
1629
1630 if (_active_workers > 1) {
1631 steal_marking_work(_terminator, worker_id);
1632 }
1633 }
1634 };
1635
1636 class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
1637 TaskTerminator _terminator;
1638
1639 public:
1640 ParallelCompactRefProcProxyTask(uint max_workers)
1641 : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers),
1642 _terminator(_max_workers, ParCompactionManager::oop_task_queues()) {}
1643
1644 void work(uint worker_id) override {
1645 assert(worker_id < _max_workers, "sanity");
1646 ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
1647 PCMarkAndPushClosure keep_alive(cm);
1648 BarrierEnqueueDiscoveredFieldClosure enqueue;
1649 ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
1650 _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &keep_alive, &enqueue, &complete_gc);
1651 }
1652
1653 void prepare_run_task_hook() override {
1654 _terminator.reset_for_reuse(_queue_count);
1655 }
1656 };
1657
1658 static void flush_marking_stats_cache(const uint num_workers) {
1659 for (uint i = 0; i < num_workers; ++i) {
1660 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(i);
1661 cm->flush_and_destroy_marking_stats_cache();
1662 }
1663 }
1664
1665 void PSParallelCompact::marking_phase(ParallelOldTracer *gc_tracer) {
1666 // Recursively traverse all live objects and mark them
1667 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
1668
1669 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
1670
1671 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_mark);
1672 {
1673 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
1674
1675 MarkFromRootsTask task(active_gc_threads);
1676 ParallelScavengeHeap::heap()->workers().run_task(&task);
1677 }
1678
1679 // Process reference objects found during marking
1680 {
1681 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
1682
1683 ReferenceProcessorStats stats;
1684 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
1685
1686 ref_processor()->set_active_mt_degree(active_gc_threads);
1687 ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues());
1688 stats = ref_processor()->process_discovered_references(task, pt);
1689
1690 gc_tracer->report_gc_reference_stats(stats);
1691 pt.print_all_references();
1692 }
1693
1694 {
1695 GCTraceTime(Debug, gc, phases) tm("Flush Marking Stats", &_gc_timer);
1696
1697 flush_marking_stats_cache(active_gc_threads);
1698 }
1699
1700 // This is the point where the entire marking should have completed.
1701 ParCompactionManager::verify_all_marking_stack_empty();
1702
1703 {
1704 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
1705 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(),
1706 is_alive_closure(),
1707 &do_nothing_cl,
1708 1);
1709 }
1710
1711 {
1712 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
1713
1714 ClassUnloadingContext* ctx = ClassUnloadingContext::context();
1715
1716 bool unloading_occurred;
1717 {
1718 CodeCache::UnlinkingScope scope(is_alive_closure());
1719
1720 // Follow system dictionary roots and unload classes.
1721 unloading_occurred = SystemDictionary::do_unloading(&_gc_timer);
1722
1723 // Unload nmethods.
1724 CodeCache::do_unloading(unloading_occurred);
1725 }
1726
1727 {
1728 GCTraceTime(Debug, gc, phases) t("Purge Unlinked NMethods", gc_timer());
1729 // Release unloaded nmethod's memory.
1730 ctx->purge_nmethods();
1731 }
1732 {
1733 GCTraceTime(Debug, gc, phases) ur("Unregister NMethods", &_gc_timer);
1734 ParallelScavengeHeap::heap()->prune_unlinked_nmethods();
1735 }
1736 {
1737 GCTraceTime(Debug, gc, phases) t("Free Code Blobs", gc_timer());
1738 ctx->free_nmethods();
1739 }
1740
1741 // Prune dead klasses from subklass/sibling/implementor lists.
1742 Klass::clean_weak_klass_links(unloading_occurred);
1743
1744 // Clean JVMCI metadata handles.
1745 JVMCI_ONLY(JVMCI::do_unloading(unloading_occurred));
1746 }
1747
1748 {
1749 GCTraceTime(Debug, gc, phases) tm("Report Object Count", &_gc_timer);
1750 _gc_tracer.report_object_count_after_gc(is_alive_closure(), &ParallelScavengeHeap::heap()->workers());
1751 }
1752 #if TASKQUEUE_STATS
1753 ParCompactionManager::oop_task_queues()->print_and_reset_taskqueue_stats("Oop Queue");
1754 ParCompactionManager::_objarray_task_queues->print_and_reset_taskqueue_stats("ObjArrayOop Queue");
1755 #endif
1756 }
1757
1758 class PSAdjustTask final : public WorkerTask {
1759 SubTasksDone _sub_tasks;
1760 WeakProcessor::Task _weak_proc_task;
1761 OopStorageSetStrongParState<false, false> _oop_storage_iter;
1762 uint _nworkers;
1763
1764 enum PSAdjustSubTask {
1765 PSAdjustSubTask_code_cache,
1766
1767 PSAdjustSubTask_num_elements
1768 };
1769
1770 public:
1771 PSAdjustTask(uint nworkers) :
1772 WorkerTask("PSAdjust task"),
1773 _sub_tasks(PSAdjustSubTask_num_elements),
1774 _weak_proc_task(nworkers),
1775 _nworkers(nworkers) {
1776
1777 ClassLoaderDataGraph::verify_claimed_marks_cleared(ClassLoaderData::_claim_stw_fullgc_adjust);
1778 if (nworkers > 1) {
1779 Threads::change_thread_claim_token();
1780 }
1781 }
1782
1783 ~PSAdjustTask() {
1784 Threads::assert_all_threads_claimed();
1785 }
1786
1787 void work(uint worker_id) {
1788 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1789 PCAdjustPointerClosure adjust(cm);
1790 {
1791 ResourceMark rm;
1792 Threads::possibly_parallel_oops_do(_nworkers > 1, &adjust, nullptr);
1793 }
1794 _oop_storage_iter.oops_do(&adjust);
1795 {
1796 CLDToOopClosure cld_closure(&adjust, ClassLoaderData::_claim_stw_fullgc_adjust);
1797 ClassLoaderDataGraph::cld_do(&cld_closure);
1798 }
1799 {
1800 AlwaysTrueClosure always_alive;
1801 _weak_proc_task.work(worker_id, &always_alive, &adjust);
1802 }
1803 if (_sub_tasks.try_claim_task(PSAdjustSubTask_code_cache)) {
1804 NMethodToOopClosure adjust_code(&adjust, NMethodToOopClosure::FixRelocations);
1805 CodeCache::nmethods_do(&adjust_code);
1806 }
1807 _sub_tasks.all_tasks_claimed();
1808 }
1809 };
1810
1811 void PSParallelCompact::adjust_roots() {
1812 // Adjust the pointers to reflect the new locations
1813 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
1814 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
1815 PSAdjustTask task(nworkers);
1816 ParallelScavengeHeap::heap()->workers().run_task(&task);
1817 }
1818
1819 // Helper class to print 8 region numbers per line and then print the total at the end.
1820 class FillableRegionLogger : public StackObj {
1821 private:
1822 Log(gc, compaction) log;
1823 static const int LineLength = 8;
1824 size_t _regions[LineLength];
1825 int _next_index;
1826 bool _enabled;
1827 size_t _total_regions;
1828 public:
1829 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
1830 ~FillableRegionLogger() {
1831 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
1832 }
1833
1834 void print_line() {
1835 if (!_enabled || _next_index == 0) {
1836 return;
1837 }
1838 FormatBuffer<> line("Fillable: ");
1839 for (int i = 0; i < _next_index; i++) {
1840 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
1841 }
1842 log.trace("%s", line.buffer());
1843 _next_index = 0;
1844 }
1845
1846 void handle(size_t region) {
1847 if (!_enabled) {
1848 return;
1849 }
1850 _regions[_next_index++] = region;
1851 if (_next_index == LineLength) {
1852 print_line();
1853 }
1854 _total_regions++;
1855 }
1856 };
1857
1858 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
1859 {
1860 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
1861
1862 // Find the threads that are active
1863 uint worker_id = 0;
1864
1865 // Find all regions that are available (can be filled immediately) and
1866 // distribute them to the thread stacks. The iteration is done in reverse
1867 // order (high to low) so the regions will be removed in ascending order.
1868
1869 const ParallelCompactData& sd = PSParallelCompact::summary_data();
1870
1871 // id + 1 is used to test termination so unsigned can
1872 // be used with an old_space_id == 0.
1873 FillableRegionLogger region_logger;
1874 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
1875 SpaceInfo* const space_info = _space_info + id;
1876 HeapWord* const new_top = space_info->new_top();
1877
1878 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
1879 const size_t end_region =
1880 sd.addr_to_region_idx(sd.region_align_up(new_top));
1881
1882 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
1883 if (sd.region(cur)->claim_unsafe()) {
1884 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1885 bool result = sd.region(cur)->mark_normal();
1886 assert(result, "Must succeed at this point.");
1887 cm->region_stack()->push(cur);
1888 region_logger.handle(cur);
1889 // Assign regions to tasks in round-robin fashion.
1890 if (++worker_id == parallel_gc_threads) {
1891 worker_id = 0;
1892 }
1893 }
1894 }
1895 region_logger.print_line();
1896 }
1897 }
1898
1899 class TaskQueue : StackObj {
1900 volatile uint _counter;
1901 uint _size;
1902 uint _insert_index;
1903 PSParallelCompact::UpdateDensePrefixTask* _backing_array;
1904 public:
1905 explicit TaskQueue(uint size) : _counter(0), _size(size), _insert_index(0), _backing_array(nullptr) {
1906 _backing_array = NEW_C_HEAP_ARRAY(PSParallelCompact::UpdateDensePrefixTask, _size, mtGC);
1907 }
1908 ~TaskQueue() {
1909 assert(_counter >= _insert_index, "not all queue elements were claimed");
1910 FREE_C_HEAP_ARRAY(T, _backing_array);
1911 }
1912
1913 void push(const PSParallelCompact::UpdateDensePrefixTask& value) {
1914 assert(_insert_index < _size, "too small backing array");
1915 _backing_array[_insert_index++] = value;
1916 }
1917
1918 bool try_claim(PSParallelCompact::UpdateDensePrefixTask& reference) {
1919 uint claimed = Atomic::fetch_then_add(&_counter, 1u);
1920 if (claimed < _insert_index) {
1921 reference = _backing_array[claimed];
1922 return true;
1923 } else {
1924 return false;
1925 }
1926 }
1927 };
1928
1929 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
1930
1931 void PSParallelCompact::enqueue_dense_prefix_tasks(TaskQueue& task_queue,
1932 uint parallel_gc_threads) {
1933 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
1934
1935 ParallelCompactData& sd = PSParallelCompact::summary_data();
1936
1937 // Iterate over all the spaces adding tasks for updating
1938 // regions in the dense prefix. Assume that 1 gc thread
1939 // will work on opening the gaps and the remaining gc threads
1940 // will work on the dense prefix.
1941 unsigned int space_id;
1942 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
1943 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
1944 const MutableSpace* const space = _space_info[space_id].space();
1945
1946 if (dense_prefix_end == space->bottom()) {
1947 // There is no dense prefix for this space.
1948 continue;
1949 }
1950
1951 // The dense prefix is before this region.
1952 size_t region_index_end_dense_prefix =
1953 sd.addr_to_region_idx(dense_prefix_end);
1954 RegionData* const dense_prefix_cp =
1955 sd.region(region_index_end_dense_prefix);
1956 assert(dense_prefix_end == space->end() ||
1957 dense_prefix_cp->available() ||
1958 dense_prefix_cp->claimed(),
1959 "The region after the dense prefix should always be ready to fill");
1960
1961 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
1962
1963 // Is there dense prefix work?
1964 size_t total_dense_prefix_regions =
1965 region_index_end_dense_prefix - region_index_start;
1966 // How many regions of the dense prefix should be given to
1967 // each thread?
1968 if (total_dense_prefix_regions > 0) {
1969 uint tasks_for_dense_prefix = 1;
1970 if (total_dense_prefix_regions <=
1971 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
1972 // Don't over partition. This assumes that
1973 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
1974 // so there are not many regions to process.
1975 tasks_for_dense_prefix = parallel_gc_threads;
1976 } else {
1977 // Over partition
1978 tasks_for_dense_prefix = parallel_gc_threads *
1979 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
1980 }
1981 size_t regions_per_thread = total_dense_prefix_regions /
1982 tasks_for_dense_prefix;
1983 // Give each thread at least 1 region.
1984 if (regions_per_thread == 0) {
1985 regions_per_thread = 1;
1986 }
1987
1988 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
1989 if (region_index_start >= region_index_end_dense_prefix) {
1990 break;
1991 }
1992 // region_index_end is not processed
1993 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
1994 region_index_end_dense_prefix);
1995 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
1996 region_index_start,
1997 region_index_end));
1998 region_index_start = region_index_end;
1999 }
2000 }
2001 // This gets any part of the dense prefix that did not
2002 // fit evenly.
2003 if (region_index_start < region_index_end_dense_prefix) {
2004 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
2005 region_index_start,
2006 region_index_end_dense_prefix));
2007 }
2008 }
2009 }
2010
2011 #ifdef ASSERT
2012 // Write a histogram of the number of times the block table was filled for a
2013 // region.
2014 void PSParallelCompact::write_block_fill_histogram()
2015 {
2016 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2017 return;
2018 }
2019
2020 Log(gc, compaction) log;
2021 ResourceMark rm;
2022 LogStream ls(log.trace());
2023 outputStream* out = &ls;
2024
2025 typedef ParallelCompactData::RegionData rd_t;
2026 ParallelCompactData& sd = summary_data();
2027
2028 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2029 MutableSpace* const spc = _space_info[id].space();
2030 if (spc->bottom() != spc->top()) {
2031 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2032 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2033 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2034
2035 size_t histo[5] = { 0, 0, 0, 0, 0 };
2036 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2037 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2038
2039 for (const rd_t* cur = beg; cur < end; ++cur) {
2040 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2041 }
2042 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2043 for (size_t i = 0; i < histo_len; ++i) {
2044 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2045 histo[i], 100.0 * histo[i] / region_cnt);
2046 }
2047 out->cr();
2048 }
2049 }
2050 }
2051 #endif // #ifdef ASSERT
2052
2053 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
2054 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2055
2056 ParCompactionManager* cm =
2057 ParCompactionManager::gc_thread_compaction_manager(worker_id);
2058
2059 // Drain the stacks that have been preloaded with regions
2060 // that are ready to fill.
2061
2062 cm->drain_region_stacks();
2063
2064 guarantee(cm->region_stack()->is_empty(), "Not empty");
2065
2066 size_t region_index = 0;
2067
2068 while (true) {
2069 if (ParCompactionManager::steal(worker_id, region_index)) {
2070 PSParallelCompact::fill_and_update_region(cm, region_index);
2071 cm->drain_region_stacks();
2072 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
2073 // Fill and update an unavailable region with the help of a shadow region
2074 PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
2075 cm->drain_region_stacks();
2076 } else {
2077 if (terminator->offer_termination()) {
2078 break;
2079 }
2080 // Go around again.
2081 }
2082 }
2083 }
2084
2085 class UpdateDensePrefixAndCompactionTask: public WorkerTask {
2086 TaskQueue& _tq;
2087 TaskTerminator _terminator;
2088
2089 public:
2090 UpdateDensePrefixAndCompactionTask(TaskQueue& tq, uint active_workers) :
2091 WorkerTask("UpdateDensePrefixAndCompactionTask"),
2092 _tq(tq),
2093 _terminator(active_workers, ParCompactionManager::region_task_queues()) {
2094 }
2095 virtual void work(uint worker_id) {
2096 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2097
2098 for (PSParallelCompact::UpdateDensePrefixTask task; _tq.try_claim(task); /* empty */) {
2099 PSParallelCompact::update_and_deadwood_in_dense_prefix(cm,
2100 task._space_id,
2101 task._region_index_start,
2102 task._region_index_end);
2103 }
2104
2105 // Once a thread has drained it's stack, it should try to steal regions from
2106 // other threads.
2107 compaction_with_stealing_work(&_terminator, worker_id);
2108
2109 // At this point all regions have been compacted, so it's now safe
2110 // to update the deferred objects that cross region boundaries.
2111 cm->drain_deferred_objects();
2112 }
2113 };
2114
2115 void PSParallelCompact::compact() {
2116 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2117
2118 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2119 PSOldGen* old_gen = heap->old_gen();
2120 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2121
2122 // for [0..last_space_id)
2123 // for [0..active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)
2124 // push
2125 // push
2126 //
2127 // max push count is thus: last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1)
2128 TaskQueue task_queue(last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1));
2129 initialize_shadow_regions(active_gc_threads);
2130 prepare_region_draining_tasks(active_gc_threads);
2131 enqueue_dense_prefix_tasks(task_queue, active_gc_threads);
2132
2133 {
2134 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2135
2136 UpdateDensePrefixAndCompactionTask task(task_queue, active_gc_threads);
2137 ParallelScavengeHeap::heap()->workers().run_task(&task);
2138
2139 #ifdef ASSERT
2140 // Verify that all regions have been processed.
2141 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2142 verify_complete(SpaceId(id));
2143 }
2144 #endif
2145 }
2146
2147 DEBUG_ONLY(write_block_fill_histogram());
2148 }
2149
2150 #ifdef ASSERT
2151 void PSParallelCompact::verify_complete(SpaceId space_id) {
2152 // All Regions between space bottom() to new_top() should be marked as filled
2153 // and all Regions between new_top() and top() should be available (i.e.,
2154 // should have been emptied).
2155 ParallelCompactData& sd = summary_data();
2156 SpaceInfo si = _space_info[space_id];
2157 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2158 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2159 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2160 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2161 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2162
2163 bool issued_a_warning = false;
2164
2165 size_t cur_region;
2166 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2167 const RegionData* const c = sd.region(cur_region);
2168 if (!c->completed()) {
2169 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2170 cur_region, c->destination_count());
2171 issued_a_warning = true;
2172 }
2173 }
2174
2175 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2176 const RegionData* const c = sd.region(cur_region);
2177 if (!c->available()) {
2178 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2179 cur_region, c->destination_count());
2180 issued_a_warning = true;
2181 }
2182 }
2183
2184 if (issued_a_warning) {
2185 print_region_ranges();
2186 }
2187 }
2188 #endif // #ifdef ASSERT
2189
2190 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2191 compaction_manager()->update_contents(cast_to_oop(addr));
2192 }
2193
2194 // Update interior oops in the ranges of regions [beg_region, end_region).
2195 void
2196 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2197 SpaceId space_id,
2198 size_t beg_region,
2199 size_t end_region) {
2200 ParallelCompactData& sd = summary_data();
2201 ParMarkBitMap* const mbm = mark_bitmap();
2202
2203 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2204 HeapWord* const end_addr = sd.region_to_addr(end_region);
2205 assert(beg_region <= end_region, "bad region range");
2206 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2207
2208 #ifdef ASSERT
2209 // Claim the regions to avoid triggering an assert when they are marked as
2210 // filled.
2211 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2212 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2213 }
2214 #endif // #ifdef ASSERT
2215 HeapWord* const space_bottom = space(space_id)->bottom();
2216
2217 // Check if it's the first region in this space.
2218 if (beg_addr != space_bottom) {
2219 // Find the first live object or block of dead space that *starts* in this
2220 // range of regions. If a partial object crosses onto the region, skip it;
2221 // it will be marked for 'deferred update' when the object head is
2222 // processed. If dead space crosses onto the region, it is also skipped; it
2223 // will be filled when the prior region is processed. If neither of those
2224 // apply, the first word in the region is the start of a live object or dead
2225 // space.
2226 assert(beg_addr > space(space_id)->bottom(), "sanity");
2227 const RegionData* const cp = sd.region(beg_region);
2228 if (cp->partial_obj_size() != 0) {
2229 beg_addr = sd.partial_obj_end(beg_region);
2230 } else {
2231 idx_t beg_bit = mbm->addr_to_bit(beg_addr);
2232 if (!mbm->is_obj_beg(beg_bit) && !mbm->is_obj_end(beg_bit - 1)) {
2233 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2234 }
2235 }
2236 }
2237
2238 if (beg_addr < end_addr) {
2239 // A live object or block of dead space starts in this range of Regions.
2240 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2241
2242 // Create closures and iterate.
2243 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2244 FillClosure fill_closure(cm, space_id);
2245 mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr, dense_prefix_end);
2246 }
2247
2248 // Mark the regions as filled.
2249 RegionData* const beg_cp = sd.region(beg_region);
2250 RegionData* const end_cp = sd.region(end_region);
2251 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2252 cp->set_completed();
2253 }
2254 }
2255
2256 // Return the SpaceId for the space containing addr. If addr is not in the
2257 // heap, last_space_id is returned. In debug mode it expects the address to be
2258 // in the heap and asserts such.
2259 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2260 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2261
2262 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2263 if (_space_info[id].space()->contains(addr)) {
2264 return SpaceId(id);
2265 }
2266 }
2267
2268 assert(false, "no space contains the addr");
2269 return last_space_id;
2270 }
2271
2272 void PSParallelCompact::update_deferred_object(ParCompactionManager* cm, HeapWord *addr) {
2273 #ifdef ASSERT
2274 ParallelCompactData& sd = summary_data();
2275 size_t region_idx = sd.addr_to_region_idx(addr);
2276 assert(sd.region(region_idx)->completed(), "first region must be completed before deferred updates");
2277 assert(sd.region(region_idx + 1)->completed(), "second region must be completed before deferred updates");
2278 #endif
2279
2280 const SpaceInfo* const space_info = _space_info + space_id(addr);
2281 ObjectStartArray* const start_array = space_info->start_array();
2282 if (start_array != nullptr) {
2283 start_array->update_for_block(addr, addr + cast_to_oop(addr)->size());
2284 }
2285
2286 cm->update_contents(cast_to_oop(addr));
2287 assert(oopDesc::is_oop(cast_to_oop(addr)), "Expected an oop at " PTR_FORMAT, p2i(cast_to_oop(addr)));
2288 }
2289
2290 // Skip over count live words starting from beg, and return the address of the
2291 // next live word. Unless marked, the word corresponding to beg is assumed to
2292 // be dead. Callers must either ensure beg does not correspond to the middle of
2293 // an object, or account for those live words in some other way. Callers must
2294 // also ensure that there are enough live words in the range [beg, end) to skip.
2295 HeapWord*
2296 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2297 {
2298 assert(count > 0, "sanity");
2299
2300 ParMarkBitMap* m = mark_bitmap();
2301 idx_t bits_to_skip = m->words_to_bits(count);
2302 idx_t cur_beg = m->addr_to_bit(beg);
2303 const idx_t search_end = m->align_range_end(m->addr_to_bit(end));
2304
2305 do {
2306 cur_beg = m->find_obj_beg(cur_beg, search_end);
2307 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2308 const size_t obj_bits = cur_end - cur_beg + 1;
2309 if (obj_bits > bits_to_skip) {
2310 return m->bit_to_addr(cur_beg + bits_to_skip);
2311 }
2312 bits_to_skip -= obj_bits;
2313 cur_beg = cur_end + 1;
2314 } while (bits_to_skip > 0);
2315
2316 // Skipping the desired number of words landed just past the end of an object.
2317 // Find the start of the next object.
2318 cur_beg = m->find_obj_beg(cur_beg, search_end);
2319 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2320 return m->bit_to_addr(cur_beg);
2321 }
2322
2323 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2324 SpaceId src_space_id,
2325 size_t src_region_idx)
2326 {
2327 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2328
2329 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2330 if (split_info.dest_region_addr() == dest_addr) {
2331 // The partial object ending at the split point contains the first word to
2332 // be copied to dest_addr.
2333 return split_info.first_src_addr();
2334 }
2335
2336 const ParallelCompactData& sd = summary_data();
2337 ParMarkBitMap* const bitmap = mark_bitmap();
2338 const size_t RegionSize = ParallelCompactData::RegionSize;
2339
2340 assert(sd.is_region_aligned(dest_addr), "not aligned");
2341 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2342 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2343 HeapWord* const src_region_destination = src_region_ptr->destination();
2344
2345 assert(dest_addr >= src_region_destination, "wrong src region");
2346 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2347
2348 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2349 HeapWord* const src_region_end = src_region_beg + RegionSize;
2350
2351 HeapWord* addr = src_region_beg;
2352 if (dest_addr == src_region_destination) {
2353 // Return the first live word in the source region.
2354 if (partial_obj_size == 0) {
2355 addr = bitmap->find_obj_beg(addr, src_region_end);
2356 assert(addr < src_region_end, "no objects start in src region");
2357 }
2358 return addr;
2359 }
2360
2361 // Must skip some live data.
2362 size_t words_to_skip = dest_addr - src_region_destination;
2363 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2364
2365 if (partial_obj_size >= words_to_skip) {
2366 // All the live words to skip are part of the partial object.
2367 addr += words_to_skip;
2368 if (partial_obj_size == words_to_skip) {
2369 // Find the first live word past the partial object.
2370 addr = bitmap->find_obj_beg(addr, src_region_end);
2371 assert(addr < src_region_end, "wrong src region");
2372 }
2373 return addr;
2374 }
2375
2376 // Skip over the partial object (if any).
2377 if (partial_obj_size != 0) {
2378 words_to_skip -= partial_obj_size;
2379 addr += partial_obj_size;
2380 }
2381
2382 // Skip over live words due to objects that start in the region.
2383 addr = skip_live_words(addr, src_region_end, words_to_skip);
2384 assert(addr < src_region_end, "wrong src region");
2385 return addr;
2386 }
2387
2388 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2389 SpaceId src_space_id,
2390 size_t beg_region,
2391 HeapWord* end_addr)
2392 {
2393 ParallelCompactData& sd = summary_data();
2394
2395 #ifdef ASSERT
2396 MutableSpace* const src_space = _space_info[src_space_id].space();
2397 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2398 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2399 "src_space_id does not match beg_addr");
2400 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2401 "src_space_id does not match end_addr");
2402 #endif // #ifdef ASSERT
2403
2404 RegionData* const beg = sd.region(beg_region);
2405 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2406
2407 // Regions up to new_top() are enqueued if they become available.
2408 HeapWord* const new_top = _space_info[src_space_id].new_top();
2409 RegionData* const enqueue_end =
2410 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2411
2412 for (RegionData* cur = beg; cur < end; ++cur) {
2413 assert(cur->data_size() > 0, "region must have live data");
2414 cur->decrement_destination_count();
2415 if (cur < enqueue_end && cur->available() && cur->claim()) {
2416 if (cur->mark_normal()) {
2417 cm->push_region(sd.region(cur));
2418 } else if (cur->mark_copied()) {
2419 // Try to copy the content of the shadow region back to its corresponding
2420 // heap region if the shadow region is filled. Otherwise, the GC thread
2421 // fills the shadow region will copy the data back (see
2422 // MoveAndUpdateShadowClosure::complete_region).
2423 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2424 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2425 cur->set_completed();
2426 }
2427 }
2428 }
2429 }
2430
2431 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2432 SpaceId& src_space_id,
2433 HeapWord*& src_space_top,
2434 HeapWord* end_addr)
2435 {
2436 typedef ParallelCompactData::RegionData RegionData;
2437
2438 ParallelCompactData& sd = PSParallelCompact::summary_data();
2439 const size_t region_size = ParallelCompactData::RegionSize;
2440
2441 size_t src_region_idx = 0;
2442
2443 // Skip empty regions (if any) up to the top of the space.
2444 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2445 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2446 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2447 const RegionData* const top_region_ptr =
2448 sd.addr_to_region_ptr(top_aligned_up);
2449 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2450 ++src_region_ptr;
2451 }
2452
2453 if (src_region_ptr < top_region_ptr) {
2454 // The next source region is in the current space. Update src_region_idx
2455 // and the source address to match src_region_ptr.
2456 src_region_idx = sd.region(src_region_ptr);
2457 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2458 if (src_region_addr > closure.source()) {
2459 closure.set_source(src_region_addr);
2460 }
2461 return src_region_idx;
2462 }
2463
2464 // Switch to a new source space and find the first non-empty region.
2465 unsigned int space_id = src_space_id + 1;
2466 assert(space_id < last_space_id, "not enough spaces");
2467
2468 HeapWord* const destination = closure.destination();
2469
2470 do {
2471 MutableSpace* space = _space_info[space_id].space();
2472 HeapWord* const bottom = space->bottom();
2473 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2474
2475 // Iterate over the spaces that do not compact into themselves.
2476 if (bottom_cp->destination() != bottom) {
2477 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2478 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2479
2480 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2481 if (src_cp->live_obj_size() > 0) {
2482 // Found it.
2483 assert(src_cp->destination() == destination,
2484 "first live obj in the space must match the destination");
2485 assert(src_cp->partial_obj_size() == 0,
2486 "a space cannot begin with a partial obj");
2487
2488 src_space_id = SpaceId(space_id);
2489 src_space_top = space->top();
2490 const size_t src_region_idx = sd.region(src_cp);
2491 closure.set_source(sd.region_to_addr(src_region_idx));
2492 return src_region_idx;
2493 } else {
2494 assert(src_cp->data_size() == 0, "sanity");
2495 }
2496 }
2497 }
2498 } while (++space_id < last_space_id);
2499
2500 assert(false, "no source region was found");
2501 return 0;
2502 }
2503
2504 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2505 {
2506 typedef ParMarkBitMap::IterationStatus IterationStatus;
2507 ParMarkBitMap* const bitmap = mark_bitmap();
2508 ParallelCompactData& sd = summary_data();
2509 RegionData* const region_ptr = sd.region(region_idx);
2510
2511 // Get the source region and related info.
2512 size_t src_region_idx = region_ptr->source_region();
2513 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2514 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2515 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2516
2517 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2518
2519 // Adjust src_region_idx to prepare for decrementing destination counts (the
2520 // destination count is not decremented when a region is copied to itself).
2521 if (src_region_idx == region_idx) {
2522 src_region_idx += 1;
2523 }
2524
2525 if (bitmap->is_unmarked(closure.source())) {
2526 // The first source word is in the middle of an object; copy the remainder
2527 // of the object or as much as will fit. The fact that pointer updates were
2528 // deferred will be noted when the object header is processed.
2529 HeapWord* const old_src_addr = closure.source();
2530 closure.copy_partial_obj();
2531 if (closure.is_full()) {
2532 decrement_destination_counts(cm, src_space_id, src_region_idx,
2533 closure.source());
2534 closure.complete_region(cm, dest_addr, region_ptr);
2535 return;
2536 }
2537
2538 HeapWord* const end_addr = sd.region_align_down(closure.source());
2539 if (sd.region_align_down(old_src_addr) != end_addr) {
2540 // The partial object was copied from more than one source region.
2541 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2542
2543 // Move to the next source region, possibly switching spaces as well. All
2544 // args except end_addr may be modified.
2545 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2546 end_addr);
2547 }
2548 }
2549
2550 do {
2551 HeapWord* const cur_addr = closure.source();
2552 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2553 src_space_top);
2554 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2555
2556 if (status == ParMarkBitMap::would_overflow) {
2557 // The last object did not fit. Note that interior oop updates were
2558 // deferred, then copy enough of the object to fill the region.
2559 cm->push_deferred_object(closure.destination());
2560 status = closure.copy_until_full(); // copies from closure.source()
2561
2562 decrement_destination_counts(cm, src_space_id, src_region_idx,
2563 closure.source());
2564 closure.complete_region(cm, dest_addr, region_ptr);
2565 return;
2566 }
2567
2568 if (status == ParMarkBitMap::full) {
2569 decrement_destination_counts(cm, src_space_id, src_region_idx,
2570 closure.source());
2571 closure.complete_region(cm, dest_addr, region_ptr);
2572 return;
2573 }
2574
2575 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2576
2577 // Move to the next source region, possibly switching spaces as well. All
2578 // args except end_addr may be modified.
2579 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2580 end_addr);
2581 } while (true);
2582 }
2583
2584 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
2585 {
2586 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
2587 fill_region(cm, cl, region_idx);
2588 }
2589
2590 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
2591 {
2592 // Get a shadow region first
2593 ParallelCompactData& sd = summary_data();
2594 RegionData* const region_ptr = sd.region(region_idx);
2595 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
2596 // The InvalidShadow return value indicates the corresponding heap region is available,
2597 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
2598 // MoveAndUpdateShadowClosure to fill the acquired shadow region.
2599 if (shadow_region == ParCompactionManager::InvalidShadow) {
2600 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
2601 region_ptr->shadow_to_normal();
2602 return fill_region(cm, cl, region_idx);
2603 } else {
2604 MoveAndUpdateShadowClosure cl(mark_bitmap(), cm, region_idx, shadow_region);
2605 return fill_region(cm, cl, region_idx);
2606 }
2607 }
2608
2609 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
2610 {
2611 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
2612 }
2613
2614 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx)
2615 {
2616 size_t next = cm->next_shadow_region();
2617 ParallelCompactData& sd = summary_data();
2618 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
2619 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2620
2621 while (next < old_new_top) {
2622 if (sd.region(next)->mark_shadow()) {
2623 region_idx = next;
2624 return true;
2625 }
2626 next = cm->move_next_shadow_region_by(active_gc_threads);
2627 }
2628
2629 return false;
2630 }
2631
2632 // The shadow region is an optimization to address region dependencies in full GC. The basic
2633 // idea is making more regions available by temporally storing their live objects in empty
2634 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
2635 // GC threads need not wait destination regions to be available before processing sources.
2636 //
2637 // A typical workflow would be:
2638 // After draining its own stack and failing to steal from others, a GC worker would pick an
2639 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
2640 // the shadow region by copying live objects from source regions of the unavailable one. Once
2641 // the unavailable region becomes available, the data in the shadow region will be copied back.
2642 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
2643 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
2644 {
2645 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2646
2647 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2648 SpaceInfo* const space_info = _space_info + id;
2649 MutableSpace* const space = space_info->space();
2650
2651 const size_t beg_region =
2652 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
2653 const size_t end_region =
2654 sd.addr_to_region_idx(sd.region_align_down(space->end()));
2655
2656 for (size_t cur = beg_region; cur < end_region; ++cur) {
2657 ParCompactionManager::push_shadow_region(cur);
2658 }
2659 }
2660
2661 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
2662 for (uint i = 0; i < parallel_gc_threads; i++) {
2663 ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i);
2664 cm->set_next_shadow_region(beg_region + i);
2665 }
2666 }
2667
2668 void PSParallelCompact::fill_blocks(size_t region_idx)
2669 {
2670 // Fill in the block table elements for the specified region. Each block
2671 // table element holds the number of live words in the region that are to the
2672 // left of the first object that starts in the block. Thus only blocks in
2673 // which an object starts need to be filled.
2674 //
2675 // The algorithm scans the section of the bitmap that corresponds to the
2676 // region, keeping a running total of the live words. When an object start is
2677 // found, if it's the first to start in the block that contains it, the
2678 // current total is written to the block table element.
2679 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2680 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2681 const size_t RegionSize = ParallelCompactData::RegionSize;
2682
2683 ParallelCompactData& sd = summary_data();
2684 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2685 if (partial_obj_size >= RegionSize) {
2686 return; // No objects start in this region.
2687 }
2688
2689 // Ensure the first loop iteration decides that the block has changed.
2690 size_t cur_block = sd.block_count();
2691
2692 const ParMarkBitMap* const bitmap = mark_bitmap();
2693
2694 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2695 assert((size_t)1 << Log2BitsPerBlock ==
2696 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2697
2698 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2699 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2700 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2701 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2702 while (beg_bit < range_end) {
2703 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2704 if (new_block != cur_block) {
2705 cur_block = new_block;
2706 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2707 }
2708
2709 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2710 if (end_bit < range_end - 1) {
2711 live_bits += end_bit - beg_bit + 1;
2712 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2713 } else {
2714 return;
2715 }
2716 }
2717 }
2718
2719 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
2720 {
2721 if (source() != copy_destination()) {
2722 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2723 Copy::aligned_conjoint_words(source(), copy_destination(), words_remaining());
2724 }
2725 update_state(words_remaining());
2726 assert(is_full(), "sanity");
2727 return ParMarkBitMap::full;
2728 }
2729
2730 void MoveAndUpdateClosure::copy_partial_obj()
2731 {
2732 size_t words = words_remaining();
2733
2734 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
2735 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
2736 if (end_addr < range_end) {
2737 words = bitmap()->obj_size(source(), end_addr);
2738 }
2739
2740 // This test is necessary; if omitted, the pointer updates to a partial object
2741 // that crosses the dense prefix boundary could be overwritten.
2742 if (source() != copy_destination()) {
2743 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2744 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2745 }
2746 update_state(words);
2747 }
2748
2749 void MoveAndUpdateClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
2750 PSParallelCompact::RegionData *region_ptr) {
2751 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
2752 region_ptr->set_completed();
2753 }
2754
2755 ParMarkBitMapClosure::IterationStatus
2756 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
2757 assert(destination() != nullptr, "sanity");
2758 assert(bitmap()->obj_size(addr) == words, "bad size");
2759
2760 _source = addr;
2761 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
2762 destination(), "wrong destination");
2763
2764 if (words > words_remaining()) {
2765 return ParMarkBitMap::would_overflow;
2766 }
2767
2768 // The start_array must be updated even if the object is not moving.
2769 if (_start_array != nullptr) {
2770 _start_array->update_for_block(destination(), destination() + words);
2771 }
2772
2773 if (copy_destination() != source()) {
2774 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
2775 Copy::aligned_conjoint_words(source(), copy_destination(), words);
2776 }
2777
2778 oop moved_oop = cast_to_oop(copy_destination());
2779 compaction_manager()->update_contents(moved_oop);
2780 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or null at " PTR_FORMAT, p2i(moved_oop));
2781
2782 update_state(words);
2783 assert(copy_destination() == cast_from_oop<HeapWord*>(moved_oop) + moved_oop->size(), "sanity");
2784 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
2785 }
2786
2787 void MoveAndUpdateShadowClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
2788 PSParallelCompact::RegionData *region_ptr) {
2789 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
2790 // Record the shadow region index
2791 region_ptr->set_shadow_region(_shadow);
2792 // Mark the shadow region as filled to indicate the data is ready to be
2793 // copied back
2794 region_ptr->mark_filled();
2795 // Try to copy the content of the shadow region back to its corresponding
2796 // heap region if available; the GC thread that decreases the destination
2797 // count to zero will do the copying otherwise (see
2798 // PSParallelCompact::decrement_destination_counts).
2799 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
2800 region_ptr->set_completed();
2801 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
2802 ParCompactionManager::push_shadow_region_mt_safe(_shadow);
2803 }
2804 }
2805
2806 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
2807 ParCompactionManager* cm,
2808 PSParallelCompact::SpaceId space_id) :
2809 ParMarkBitMapClosure(mbm, cm),
2810 _start_array(PSParallelCompact::start_array(space_id))
2811 {
2812 }
2813
2814 // Updates the references in the object to their new values.
2815 ParMarkBitMapClosure::IterationStatus
2816 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
2817 do_addr(addr);
2818 return ParMarkBitMap::incomplete;
2819 }
2820
2821 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
2822 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
2823 _start_array(PSParallelCompact::start_array(space_id))
2824 {
2825 assert(space_id == PSParallelCompact::old_space_id,
2826 "cannot use FillClosure in the young gen");
2827 }
2828
2829 ParMarkBitMapClosure::IterationStatus
2830 FillClosure::do_addr(HeapWord* addr, size_t size) {
2831 CollectedHeap::fill_with_objects(addr, size);
2832 HeapWord* const end = addr + size;
2833 do {
2834 size_t size = cast_to_oop(addr)->size();
2835 _start_array->update_for_block(addr, addr + size);
2836 addr += size;
2837 } while (addr < end);
2838 return ParMarkBitMap::incomplete;
2839 }