1 /*
2 * Copyright (c) 2005, 2020, 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 "aot/aotLoader.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/stringTable.hpp"
30 #include "classfile/symbolTable.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "code/codeCache.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/psYoungGen.hpp"
44 #include "gc/shared/gcCause.hpp"
45 #include "gc/shared/gcHeapSummary.hpp"
46 #include "gc/shared/gcId.hpp"
47 #include "gc/shared/gcLocker.hpp"
48 #include "gc/shared/gcTimer.hpp"
49 #include "gc/shared/gcTrace.hpp"
50 #include "gc/shared/gcTraceTime.inline.hpp"
51 #include "gc/shared/isGCActiveMark.hpp"
52 #include "gc/shared/oopStorage.inline.hpp"
53 #include "gc/shared/oopStorageSet.inline.hpp"
54 #include "gc/shared/oopStorageSetParState.inline.hpp"
55 #include "gc/shared/referencePolicy.hpp"
56 #include "gc/shared/referenceProcessor.hpp"
57 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
58 #include "gc/shared/spaceDecorator.inline.hpp"
59 #include "gc/shared/taskTerminator.hpp"
60 #include "gc/shared/weakProcessor.hpp"
61 #include "gc/shared/workerPolicy.hpp"
62 #include "gc/shared/workgroup.hpp"
63 #include "logging/log.hpp"
64 #include "memory/iterator.inline.hpp"
65 #include "memory/resourceArea.hpp"
66 #include "memory/universe.hpp"
67 #include "oops/access.inline.hpp"
68 #include "oops/instanceClassLoaderKlass.inline.hpp"
69 #include "oops/instanceKlass.inline.hpp"
70 #include "oops/instanceMirrorKlass.inline.hpp"
71 #include "oops/methodData.hpp"
72 #include "oops/objArrayKlass.inline.hpp"
73 #include "oops/oop.inline.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/handles.inline.hpp"
76 #include "runtime/safepoint.hpp"
77 #include "runtime/vmThread.hpp"
78 #include "services/management.hpp"
79 #include "services/memTracker.hpp"
80 #include "services/memoryService.hpp"
81 #include "utilities/align.hpp"
82 #include "utilities/debug.hpp"
83 #include "utilities/events.hpp"
84 #include "utilities/formatBuffer.hpp"
85 #include "utilities/macros.hpp"
86 #include "utilities/stack.inline.hpp"
87 #if INCLUDE_JVMCI
88 #include "jvmci/jvmci.hpp"
89 #endif
90
91 #include <math.h>
92
93 // All sizes are in HeapWords.
94 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
95 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
96 const size_t ParallelCompactData::RegionSizeBytes =
97 RegionSize << LogHeapWordSize;
98 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
99 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
100 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
101
102 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
103 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
104 const size_t ParallelCompactData::BlockSizeBytes =
105 BlockSize << LogHeapWordSize;
106 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
107 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
108 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
109
110 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
111 const size_t ParallelCompactData::Log2BlocksPerRegion =
112 Log2RegionSize - Log2BlockSize;
113
114 const ParallelCompactData::RegionData::region_sz_t
115 ParallelCompactData::RegionData::dc_shift = 27;
116
117 const ParallelCompactData::RegionData::region_sz_t
118 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
119
120 const ParallelCompactData::RegionData::region_sz_t
121 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
122
123 const ParallelCompactData::RegionData::region_sz_t
124 ParallelCompactData::RegionData::los_mask = ~dc_mask;
125
126 const ParallelCompactData::RegionData::region_sz_t
127 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
128
129 const ParallelCompactData::RegionData::region_sz_t
130 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
131
132 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
133
134 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
135 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
136
137 double PSParallelCompact::_dwl_mean;
138 double PSParallelCompact::_dwl_std_dev;
139 double PSParallelCompact::_dwl_first_term;
140 double PSParallelCompact::_dwl_adjustment;
141 #ifdef ASSERT
142 bool PSParallelCompact::_dwl_initialized = false;
143 #endif // #ifdef ASSERT
144
145 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
146 HeapWord* destination)
147 {
148 assert(src_region_idx != 0, "invalid src_region_idx");
149 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
150 assert(destination != NULL, "invalid destination argument");
151
152 _src_region_idx = src_region_idx;
153 _partial_obj_size = partial_obj_size;
154 _destination = destination;
155
156 // These fields may not be updated below, so make sure they're clear.
157 assert(_dest_region_addr == NULL, "should have been cleared");
158 assert(_first_src_addr == NULL, "should have been cleared");
159
160 // Determine the number of destination regions for the partial object.
161 HeapWord* const last_word = destination + partial_obj_size - 1;
162 const ParallelCompactData& sd = PSParallelCompact::summary_data();
163 HeapWord* const beg_region_addr = sd.region_align_down(destination);
164 HeapWord* const end_region_addr = sd.region_align_down(last_word);
165
166 if (beg_region_addr == end_region_addr) {
167 // One destination region.
168 _destination_count = 1;
169 if (end_region_addr == destination) {
170 // The destination falls on a region boundary, thus the first word of the
171 // partial object will be the first word copied to the destination region.
172 _dest_region_addr = end_region_addr;
173 _first_src_addr = sd.region_to_addr(src_region_idx);
174 }
175 } else {
176 // Two destination regions. When copied, the partial object will cross a
177 // destination region boundary, so a word somewhere within the partial
178 // object will be the first word copied to the second destination region.
179 _destination_count = 2;
180 _dest_region_addr = end_region_addr;
181 const size_t ofs = pointer_delta(end_region_addr, destination);
182 assert(ofs < _partial_obj_size, "sanity");
183 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
184 }
185 }
186
187 void SplitInfo::clear()
188 {
189 _src_region_idx = 0;
190 _partial_obj_size = 0;
191 _destination = NULL;
192 _destination_count = 0;
193 _dest_region_addr = NULL;
194 _first_src_addr = NULL;
195 assert(!is_valid(), "sanity");
196 }
197
198 #ifdef ASSERT
199 void SplitInfo::verify_clear()
200 {
201 assert(_src_region_idx == 0, "not clear");
202 assert(_partial_obj_size == 0, "not clear");
203 assert(_destination == NULL, "not clear");
204 assert(_destination_count == 0, "not clear");
205 assert(_dest_region_addr == NULL, "not clear");
206 assert(_first_src_addr == NULL, "not clear");
207 }
208 #endif // #ifdef ASSERT
209
210
211 void PSParallelCompact::print_on_error(outputStream* st) {
212 _mark_bitmap.print_on_error(st);
213 }
214
215 #ifndef PRODUCT
216 const char* PSParallelCompact::space_names[] = {
217 "old ", "eden", "from", "to "
218 };
219
220 void PSParallelCompact::print_region_ranges() {
221 if (!log_develop_is_enabled(Trace, gc, compaction)) {
222 return;
223 }
224 Log(gc, compaction) log;
225 ResourceMark rm;
226 LogStream ls(log.trace());
227 Universe::print_on(&ls);
228 log.trace("space bottom top end new_top");
229 log.trace("------ ---------- ---------- ---------- ----------");
230
231 for (unsigned int id = 0; id < last_space_id; ++id) {
232 const MutableSpace* space = _space_info[id].space();
233 log.trace("%u %s "
234 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
235 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
236 id, space_names[id],
237 summary_data().addr_to_region_idx(space->bottom()),
238 summary_data().addr_to_region_idx(space->top()),
239 summary_data().addr_to_region_idx(space->end()),
240 summary_data().addr_to_region_idx(_space_info[id].new_top()));
241 }
242 }
243
244 void
245 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
246 {
247 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
248 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
249
250 ParallelCompactData& sd = PSParallelCompact::summary_data();
251 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
252 log_develop_trace(gc, compaction)(
253 REGION_IDX_FORMAT " " PTR_FORMAT " "
254 REGION_IDX_FORMAT " " PTR_FORMAT " "
255 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
256 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
257 i, p2i(c->data_location()), dci, p2i(c->destination()),
258 c->partial_obj_size(), c->live_obj_size(),
259 c->data_size(), c->source_region(), c->destination_count());
260
261 #undef REGION_IDX_FORMAT
262 #undef REGION_DATA_FORMAT
263 }
264
265 void
266 print_generic_summary_data(ParallelCompactData& summary_data,
267 HeapWord* const beg_addr,
268 HeapWord* const end_addr)
269 {
270 size_t total_words = 0;
271 size_t i = summary_data.addr_to_region_idx(beg_addr);
272 const size_t last = summary_data.addr_to_region_idx(end_addr);
273 HeapWord* pdest = 0;
274
275 while (i < last) {
276 ParallelCompactData::RegionData* c = summary_data.region(i);
277 if (c->data_size() != 0 || c->destination() != pdest) {
278 print_generic_summary_region(i, c);
279 total_words += c->data_size();
280 pdest = c->destination();
281 }
282 ++i;
283 }
284
285 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
286 }
287
288 void
289 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
290 HeapWord* const beg_addr,
291 HeapWord* const end_addr) {
292 ::print_generic_summary_data(summary_data,beg_addr, end_addr);
293 }
294
295 void
296 print_generic_summary_data(ParallelCompactData& summary_data,
297 SpaceInfo* space_info)
298 {
299 if (!log_develop_is_enabled(Trace, gc, compaction)) {
300 return;
301 }
302
303 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
304 const MutableSpace* space = space_info[id].space();
305 print_generic_summary_data(summary_data, space->bottom(),
306 MAX2(space->top(), space_info[id].new_top()));
307 }
308 }
309
310 void
311 print_initial_summary_data(ParallelCompactData& summary_data,
312 const MutableSpace* space) {
313 if (space->top() == space->bottom()) {
314 return;
315 }
316
317 const size_t region_size = ParallelCompactData::RegionSize;
318 typedef ParallelCompactData::RegionData RegionData;
319 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
320 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
321 const RegionData* c = summary_data.region(end_region - 1);
322 HeapWord* end_addr = c->destination() + c->data_size();
323 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
324
325 // Print (and count) the full regions at the beginning of the space.
326 size_t full_region_count = 0;
327 size_t i = summary_data.addr_to_region_idx(space->bottom());
328 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
329 ParallelCompactData::RegionData* c = summary_data.region(i);
330 log_develop_trace(gc, compaction)(
331 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
332 i, p2i(c->destination()),
333 c->partial_obj_size(), c->live_obj_size(),
334 c->data_size(), c->source_region(), c->destination_count());
335 ++full_region_count;
336 ++i;
337 }
338
339 size_t live_to_right = live_in_space - full_region_count * region_size;
340
341 double max_reclaimed_ratio = 0.0;
342 size_t max_reclaimed_ratio_region = 0;
343 size_t max_dead_to_right = 0;
344 size_t max_live_to_right = 0;
345
346 // Print the 'reclaimed ratio' for regions while there is something live in
347 // the region or to the right of it. The remaining regions are empty (and
348 // uninteresting), and computing the ratio will result in division by 0.
349 while (i < end_region && live_to_right > 0) {
350 c = summary_data.region(i);
351 HeapWord* const region_addr = summary_data.region_to_addr(i);
352 const size_t used_to_right = pointer_delta(space->top(), region_addr);
353 const size_t dead_to_right = used_to_right - live_to_right;
354 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
355
356 if (reclaimed_ratio > max_reclaimed_ratio) {
357 max_reclaimed_ratio = reclaimed_ratio;
358 max_reclaimed_ratio_region = i;
359 max_dead_to_right = dead_to_right;
360 max_live_to_right = live_to_right;
361 }
362
363 ParallelCompactData::RegionData* c = summary_data.region(i);
364 log_develop_trace(gc, compaction)(
365 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
366 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
367 i, p2i(c->destination()),
368 c->partial_obj_size(), c->live_obj_size(),
369 c->data_size(), c->source_region(), c->destination_count(),
370 reclaimed_ratio, dead_to_right, live_to_right);
371
372
373 live_to_right -= c->data_size();
374 ++i;
375 }
376
377 // Any remaining regions are empty. Print one more if there is one.
378 if (i < end_region) {
379 ParallelCompactData::RegionData* c = summary_data.region(i);
380 log_develop_trace(gc, compaction)(
381 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
382 i, p2i(c->destination()),
383 c->partial_obj_size(), c->live_obj_size(),
384 c->data_size(), c->source_region(), c->destination_count());
385 }
386
387 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
388 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
389 }
390
391 void
392 print_initial_summary_data(ParallelCompactData& summary_data,
393 SpaceInfo* space_info) {
394 if (!log_develop_is_enabled(Trace, gc, compaction)) {
395 return;
396 }
397
398 unsigned int id = PSParallelCompact::old_space_id;
399 const MutableSpace* space;
400 do {
401 space = space_info[id].space();
402 print_initial_summary_data(summary_data, space);
403 } while (++id < PSParallelCompact::eden_space_id);
404
405 do {
406 space = space_info[id].space();
407 print_generic_summary_data(summary_data, space->bottom(), space->top());
408 } while (++id < PSParallelCompact::last_space_id);
409 }
410 #endif // #ifndef PRODUCT
411
412 #ifdef ASSERT
413 size_t add_obj_count;
414 size_t add_obj_size;
415 size_t mark_bitmap_count;
416 size_t mark_bitmap_size;
417 #endif // #ifdef ASSERT
418
419 ParallelCompactData::ParallelCompactData() :
420 _region_start(NULL),
421 DEBUG_ONLY(_region_end(NULL) COMMA)
422 _region_vspace(NULL),
423 _reserved_byte_size(0),
424 _region_data(NULL),
425 _region_count(0),
426 _block_vspace(NULL),
427 _block_data(NULL),
428 _block_count(0) {}
429
430 bool ParallelCompactData::initialize(MemRegion covered_region)
431 {
432 _region_start = covered_region.start();
433 const size_t region_size = covered_region.word_size();
434 DEBUG_ONLY(_region_end = _region_start + region_size;)
435
436 assert(region_align_down(_region_start) == _region_start,
437 "region start not aligned");
438 assert((region_size & RegionSizeOffsetMask) == 0,
439 "region size not a multiple of RegionSize");
440
441 bool result = initialize_region_data(region_size) && initialize_block_data();
442 return result;
443 }
444
445 PSVirtualSpace*
446 ParallelCompactData::create_vspace(size_t count, size_t element_size)
447 {
448 const size_t raw_bytes = count * element_size;
449 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
450 const size_t granularity = os::vm_allocation_granularity();
451 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
452
453 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
454 MAX2(page_sz, granularity);
455 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
456 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
457 rs.size());
458
459 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
460
461 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
462 if (vspace != 0) {
463 if (vspace->expand_by(_reserved_byte_size)) {
464 return vspace;
465 }
466 delete vspace;
467 // Release memory reserved in the space.
468 rs.release();
469 }
470
471 return 0;
472 }
473
474 bool ParallelCompactData::initialize_region_data(size_t region_size)
475 {
476 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
477 _region_vspace = create_vspace(count, sizeof(RegionData));
478 if (_region_vspace != 0) {
479 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
480 _region_count = count;
481 return true;
482 }
483 return false;
484 }
485
486 bool ParallelCompactData::initialize_block_data()
487 {
488 assert(_region_count != 0, "region data must be initialized first");
489 const size_t count = _region_count << Log2BlocksPerRegion;
490 _block_vspace = create_vspace(count, sizeof(BlockData));
491 if (_block_vspace != 0) {
492 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
493 _block_count = count;
494 return true;
495 }
496 return false;
497 }
498
499 void ParallelCompactData::clear()
500 {
501 memset(_region_data, 0, _region_vspace->committed_size());
502 memset(_block_data, 0, _block_vspace->committed_size());
503 }
504
505 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
506 assert(beg_region <= _region_count, "beg_region out of range");
507 assert(end_region <= _region_count, "end_region out of range");
508 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
509
510 const size_t region_cnt = end_region - beg_region;
511 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
512
513 const size_t beg_block = beg_region * BlocksPerRegion;
514 const size_t block_cnt = region_cnt * BlocksPerRegion;
515 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
516 }
517
518 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
519 {
520 const RegionData* cur_cp = region(region_idx);
521 const RegionData* const end_cp = region(region_count() - 1);
522
523 HeapWord* result = region_to_addr(region_idx);
524 if (cur_cp < end_cp) {
525 do {
526 result += cur_cp->partial_obj_size();
527 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
528 }
529 return result;
530 }
531
532 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
533 {
534 const size_t obj_ofs = pointer_delta(addr, _region_start);
535 const size_t beg_region = obj_ofs >> Log2RegionSize;
536 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
537
538 DEBUG_ONLY(Atomic::inc(&add_obj_count);)
539 DEBUG_ONLY(Atomic::add(&add_obj_size, len);)
540
541 if (beg_region == end_region) {
542 // All in one region.
543 _region_data[beg_region].add_live_obj(len);
544 return;
545 }
546
547 // First region.
548 const size_t beg_ofs = region_offset(addr);
549 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
550
551 Klass* klass = ((oop)addr)->klass();
552 // Middle regions--completely spanned by this object.
553 for (size_t region = beg_region + 1; region < end_region; ++region) {
554 _region_data[region].set_partial_obj_size(RegionSize);
555 _region_data[region].set_partial_obj_addr(addr);
556 }
557
558 // Last region.
559 const size_t end_ofs = region_offset(addr + len - 1);
560 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
561 _region_data[end_region].set_partial_obj_addr(addr);
562 }
563
564 void
565 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
566 {
567 assert(region_offset(beg) == 0, "not RegionSize aligned");
568 assert(region_offset(end) == 0, "not RegionSize aligned");
569
570 size_t cur_region = addr_to_region_idx(beg);
571 const size_t end_region = addr_to_region_idx(end);
572 HeapWord* addr = beg;
573 while (cur_region < end_region) {
574 _region_data[cur_region].set_destination(addr);
575 _region_data[cur_region].set_destination_count(0);
576 _region_data[cur_region].set_source_region(cur_region);
577 _region_data[cur_region].set_data_location(addr);
578
579 // Update live_obj_size so the region appears completely full.
580 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
581 _region_data[cur_region].set_live_obj_size(live_size);
582
583 ++cur_region;
584 addr += RegionSize;
585 }
586 }
587
588 // Find the point at which a space can be split and, if necessary, record the
589 // split point.
590 //
591 // If the current src region (which overflowed the destination space) doesn't
592 // have a partial object, the split point is at the beginning of the current src
593 // region (an "easy" split, no extra bookkeeping required).
594 //
595 // If the current src region has a partial object, the split point is in the
596 // region where that partial object starts (call it the split_region). If
597 // split_region has a partial object, then the split point is just after that
598 // partial object (a "hard" split where we have to record the split data and
599 // zero the partial_obj_size field). With a "hard" split, we know that the
600 // partial_obj ends within split_region because the partial object that caused
601 // the overflow starts in split_region. If split_region doesn't have a partial
602 // obj, then the split is at the beginning of split_region (another "easy"
603 // split).
604 HeapWord*
605 ParallelCompactData::summarize_split_space(size_t src_region,
606 SplitInfo& split_info,
607 HeapWord* destination,
608 HeapWord* target_end,
609 HeapWord** target_next)
610 {
611 assert(destination <= target_end, "sanity");
612 assert(destination + _region_data[src_region].data_size() > target_end,
613 "region should not fit into target space");
614 assert(is_region_aligned(target_end), "sanity");
615
616 size_t split_region = src_region;
617 HeapWord* split_destination = destination;
618 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
619
620 if (destination + partial_obj_size > target_end) {
621 // The split point is just after the partial object (if any) in the
622 // src_region that contains the start of the object that overflowed the
623 // destination space.
624 //
625 // Find the start of the "overflow" object and set split_region to the
626 // region containing it.
627 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
628 split_region = addr_to_region_idx(overflow_obj);
629
630 // Clear the source_region field of all destination regions whose first word
631 // came from data after the split point (a non-null source_region field
632 // implies a region must be filled).
633 //
634 // An alternative to the simple loop below: clear during post_compact(),
635 // which uses memcpy instead of individual stores, and is easy to
636 // parallelize. (The downside is that it clears the entire RegionData
637 // object as opposed to just one field.)
638 //
639 // post_compact() would have to clear the summary data up to the highest
640 // address that was written during the summary phase, which would be
641 //
642 // max(top, max(new_top, clear_top))
643 //
644 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
645 // to target_end.
646 const RegionData* const sr = region(split_region);
647 const size_t beg_idx =
648 addr_to_region_idx(region_align_up(sr->destination() +
649 sr->partial_obj_size()));
650 const size_t end_idx = addr_to_region_idx(target_end);
651
652 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
653 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
654 _region_data[idx].set_source_region(0);
655 }
656
657 // Set split_destination and partial_obj_size to reflect the split region.
658 split_destination = sr->destination();
659 partial_obj_size = sr->partial_obj_size();
660 }
661
662 // The split is recorded only if a partial object extends onto the region.
663 if (partial_obj_size != 0) {
664 _region_data[split_region].set_partial_obj_size(0);
665 split_info.record(split_region, partial_obj_size, split_destination);
666 }
667
668 // Setup the continuation addresses.
669 *target_next = split_destination + partial_obj_size;
670 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
671
672 if (log_develop_is_enabled(Trace, gc, compaction)) {
673 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
674 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
675 split_type, p2i(source_next), split_region, partial_obj_size);
676 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
677 split_type, p2i(split_destination),
678 addr_to_region_idx(split_destination),
679 p2i(*target_next));
680
681 if (partial_obj_size != 0) {
682 HeapWord* const po_beg = split_info.destination();
683 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
684 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
685 split_type,
686 p2i(po_beg), addr_to_region_idx(po_beg),
687 p2i(po_end), addr_to_region_idx(po_end));
688 }
689 }
690
691 return source_next;
692 }
693
694 bool ParallelCompactData::summarize(SplitInfo& split_info,
695 HeapWord* source_beg, HeapWord* source_end,
696 HeapWord** source_next,
697 HeapWord* target_beg, HeapWord* target_end,
698 HeapWord** target_next)
699 {
700 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
701 log_develop_trace(gc, compaction)(
702 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
703 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
704 p2i(source_beg), p2i(source_end), p2i(source_next_val),
705 p2i(target_beg), p2i(target_end), p2i(*target_next));
706
707 size_t cur_region = addr_to_region_idx(source_beg);
708 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
709
710 HeapWord *dest_addr = target_beg;
711 while (cur_region < end_region) {
712 // The destination must be set even if the region has no data.
713 _region_data[cur_region].set_destination(dest_addr);
714
715 size_t words = _region_data[cur_region].data_size();
716 if (words > 0) {
717 // If cur_region does not fit entirely into the target space, find a point
718 // at which the source space can be 'split' so that part is copied to the
719 // target space and the rest is copied elsewhere.
720 if (dest_addr + words > target_end) {
721 assert(source_next != NULL, "source_next is NULL when splitting");
722 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
723 target_end, target_next);
724 return false;
725 }
726
727 // Compute the destination_count for cur_region, and if necessary, update
728 // source_region for a destination region. The source_region field is
729 // updated if cur_region is the first (left-most) region to be copied to a
730 // destination region.
731 //
732 // The destination_count calculation is a bit subtle. A region that has
733 // data that compacts into itself does not count itself as a destination.
734 // This maintains the invariant that a zero count means the region is
735 // available and can be claimed and then filled.
736 uint destination_count = 0;
737 if (split_info.is_split(cur_region)) {
738 // The current region has been split: the partial object will be copied
739 // to one destination space and the remaining data will be copied to
740 // another destination space. Adjust the initial destination_count and,
741 // if necessary, set the source_region field if the partial object will
742 // cross a destination region boundary.
743 destination_count = split_info.destination_count();
744 if (destination_count == 2) {
745 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
746 _region_data[dest_idx].set_source_region(cur_region);
747 }
748 }
749
750 HeapWord* const last_addr = dest_addr + words - 1;
751 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
752 const size_t dest_region_2 = addr_to_region_idx(last_addr);
753
754 // Initially assume that the destination regions will be the same and
755 // adjust the value below if necessary. Under this assumption, if
756 // cur_region == dest_region_2, then cur_region will be compacted
757 // completely into itself.
758 destination_count += cur_region == dest_region_2 ? 0 : 1;
759 if (dest_region_1 != dest_region_2) {
760 // Destination regions differ; adjust destination_count.
761 destination_count += 1;
762 // Data from cur_region will be copied to the start of dest_region_2.
763 _region_data[dest_region_2].set_source_region(cur_region);
764 } else if (region_offset(dest_addr) == 0) {
765 // Data from cur_region will be copied to the start of the destination
766 // region.
767 _region_data[dest_region_1].set_source_region(cur_region);
768 }
769
770 _region_data[cur_region].set_destination_count(destination_count);
771 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
772 dest_addr += words;
773 }
774
775 ++cur_region;
776 }
777
778 *target_next = dest_addr;
779 return true;
780 }
781
782 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
783 assert(addr != NULL, "Should detect NULL oop earlier");
784 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
785 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
786
787 // Region covering the object.
788 RegionData* const region_ptr = addr_to_region_ptr(addr);
789 HeapWord* result = region_ptr->destination();
790
791 // If the entire Region is live, the new location is region->destination + the
792 // offset of the object within in the Region.
793
794 // Run some performance tests to determine if this special case pays off. It
795 // is worth it for pointers into the dense prefix. If the optimization to
796 // avoid pointer updates in regions that only point to the dense prefix is
797 // ever implemented, this should be revisited.
798 if (region_ptr->data_size() == RegionSize) {
799 result += region_offset(addr);
800 return result;
801 }
802
803 // Otherwise, the new location is region->destination + block offset + the
804 // number of live words in the Block that are (a) to the left of addr and (b)
805 // due to objects that start in the Block.
806
807 // Fill in the block table if necessary. This is unsynchronized, so multiple
808 // threads may fill the block table for a region (harmless, since it is
809 // idempotent).
810 if (!region_ptr->blocks_filled()) {
811 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
812 region_ptr->set_blocks_filled();
813 }
814
815 HeapWord* const search_start = block_align_down(addr);
816 const size_t block_offset = addr_to_block_ptr(addr)->offset();
817
818 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
819 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
820 result += block_offset + live;
821 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
822 return result;
823 }
824
825 #ifdef ASSERT
826 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
827 {
828 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
829 const size_t* const end = (const size_t*)vspace->committed_high_addr();
830 for (const size_t* p = beg; p < end; ++p) {
831 assert(*p == 0, "not zero");
832 }
833 }
834
835 void ParallelCompactData::verify_clear()
836 {
837 verify_clear(_region_vspace);
838 verify_clear(_block_vspace);
839 }
840 #endif // #ifdef ASSERT
841
842 STWGCTimer PSParallelCompact::_gc_timer;
843 ParallelOldTracer PSParallelCompact::_gc_tracer;
844 elapsedTimer PSParallelCompact::_accumulated_time;
845 unsigned int PSParallelCompact::_total_invocations = 0;
846 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
847 jlong PSParallelCompact::_time_of_last_gc = 0;
848 CollectorCounters* PSParallelCompact::_counters = NULL;
849 ParMarkBitMap PSParallelCompact::_mark_bitmap;
850 ParallelCompactData PSParallelCompact::_summary_data;
851
852 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
853
854 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
855
856 class PCReferenceProcessor: public ReferenceProcessor {
857 public:
858 PCReferenceProcessor(
859 BoolObjectClosure* is_subject_to_discovery,
860 BoolObjectClosure* is_alive_non_header) :
861 ReferenceProcessor(is_subject_to_discovery,
862 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
863 ParallelGCThreads, // mt processing degree
864 true, // mt discovery
865 ParallelGCThreads, // mt discovery degree
866 true, // atomic_discovery
867 is_alive_non_header) {
868 }
869
870 template<typename T> bool discover(oop obj, ReferenceType type) {
871 T* referent_addr = (T*) java_lang_ref_Reference::referent_addr_raw(obj);
872 T heap_oop = RawAccess<>::oop_load(referent_addr);
873 oop referent = CompressedOops::decode_not_null(heap_oop);
874 return PSParallelCompact::mark_bitmap()->is_unmarked(referent)
875 && ReferenceProcessor::discover_reference(obj, type);
876 }
877 virtual bool discover_reference(oop obj, ReferenceType type) {
878 if (UseCompressedOops) {
879 return discover<narrowOop>(obj, type);
880 } else {
881 return discover<oop>(obj, type);
882 }
883 }
884 };
885
886 void PSParallelCompact::post_initialize() {
887 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
888 _span_based_discoverer.set_span(heap->reserved_region());
889 _ref_processor =
890 new PCReferenceProcessor(&_span_based_discoverer,
891 &_is_alive_closure); // non-header is alive closure
892
893 _counters = new CollectorCounters("Parallel full collection pauses", 1);
894
895 // Initialize static fields in ParCompactionManager.
896 ParCompactionManager::initialize(mark_bitmap());
897 }
898
899 bool PSParallelCompact::initialize() {
900 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
901 MemRegion mr = heap->reserved_region();
902
903 // Was the old gen get allocated successfully?
904 if (!heap->old_gen()->is_allocated()) {
905 return false;
906 }
907
908 initialize_space_info();
909 initialize_dead_wood_limiter();
910
911 if (!_mark_bitmap.initialize(mr)) {
912 vm_shutdown_during_initialization(
913 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
914 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
915 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
916 return false;
917 }
918
919 if (!_summary_data.initialize(mr)) {
920 vm_shutdown_during_initialization(
921 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
922 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
923 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
924 return false;
925 }
926
927 return true;
928 }
929
930 void PSParallelCompact::initialize_space_info()
931 {
932 memset(&_space_info, 0, sizeof(_space_info));
933
934 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
935 PSYoungGen* young_gen = heap->young_gen();
936
937 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
938 _space_info[eden_space_id].set_space(young_gen->eden_space());
939 _space_info[from_space_id].set_space(young_gen->from_space());
940 _space_info[to_space_id].set_space(young_gen->to_space());
941
942 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
943 }
944
945 void PSParallelCompact::initialize_dead_wood_limiter()
946 {
947 const size_t max = 100;
948 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
949 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
950 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
951 DEBUG_ONLY(_dwl_initialized = true;)
952 _dwl_adjustment = normal_distribution(1.0);
953 }
954
955 void
956 PSParallelCompact::clear_data_covering_space(SpaceId id)
957 {
958 // At this point, top is the value before GC, new_top() is the value that will
959 // be set at the end of GC. The marking bitmap is cleared to top; nothing
960 // should be marked above top. The summary data is cleared to the larger of
961 // top & new_top.
962 MutableSpace* const space = _space_info[id].space();
963 HeapWord* const bot = space->bottom();
964 HeapWord* const top = space->top();
965 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
966
967 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
968 const idx_t end_bit = _mark_bitmap.align_range_end(_mark_bitmap.addr_to_bit(top));
969 _mark_bitmap.clear_range(beg_bit, end_bit);
970
971 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
972 const size_t end_region =
973 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
974 _summary_data.clear_range(beg_region, end_region);
975
976 // Clear the data used to 'split' regions.
977 SplitInfo& split_info = _space_info[id].split_info();
978 if (split_info.is_valid()) {
979 split_info.clear();
980 }
981 DEBUG_ONLY(split_info.verify_clear();)
982 }
983
984 void PSParallelCompact::pre_compact()
985 {
986 // Update the from & to space pointers in space_info, since they are swapped
987 // at each young gen gc. Do the update unconditionally (even though a
988 // promotion failure does not swap spaces) because an unknown number of young
989 // collections will have swapped the spaces an unknown number of times.
990 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
991 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
992 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
993 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
994
995 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
996 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
997
998 // Increment the invocation count
999 heap->increment_total_collections(true);
1000
1001 // We need to track unique mark sweep invocations as well.
1002 _total_invocations++;
1003
1004 heap->print_heap_before_gc();
1005 heap->trace_heap_before_gc(&_gc_tracer);
1006
1007 // Fill in TLABs
1008 heap->ensure_parsability(true); // retire TLABs
1009
1010 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
1011 HandleMark hm; // Discard invalid handles created during verification
1012 Universe::verify("Before GC");
1013 }
1014
1015 // Verify object start arrays
1016 if (VerifyObjectStartArray &&
1017 VerifyBeforeGC) {
1018 heap->old_gen()->verify_object_start_array();
1019 }
1020
1021 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1022 DEBUG_ONLY(summary_data().verify_clear();)
1023
1024 ParCompactionManager::reset_all_bitmap_query_caches();
1025 }
1026
1027 void PSParallelCompact::post_compact()
1028 {
1029 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1030 ParCompactionManager::remove_all_shadow_regions();
1031
1032 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1033 // Clear the marking bitmap, summary data and split info.
1034 clear_data_covering_space(SpaceId(id));
1035 // Update top(). Must be done after clearing the bitmap and summary data.
1036 _space_info[id].publish_new_top();
1037 }
1038
1039 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1040 MutableSpace* const from_space = _space_info[from_space_id].space();
1041 MutableSpace* const to_space = _space_info[to_space_id].space();
1042
1043 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1044 bool eden_empty = eden_space->is_empty();
1045
1046 // Update heap occupancy information which is used as input to the soft ref
1047 // clearing policy at the next gc.
1048 Universe::update_heap_info_at_gc();
1049
1050 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1051 to_space->is_empty();
1052
1053 PSCardTable* ct = heap->card_table();
1054 MemRegion old_mr = heap->old_gen()->reserved();
1055 if (young_gen_empty) {
1056 ct->clear(MemRegion(old_mr.start(), old_mr.end()));
1057 } else {
1058 ct->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1059 }
1060
1061 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1062 ClassLoaderDataGraph::purge();
1063 MetaspaceUtils::verify_metrics();
1064
1065 heap->prune_scavengable_nmethods();
1066
1067 #if COMPILER2_OR_JVMCI
1068 DerivedPointerTable::update_pointers();
1069 #endif
1070
1071 if (ZapUnusedHeapArea) {
1072 heap->gen_mangle_unused_area();
1073 }
1074
1075 // Update time of last GC
1076 reset_millis_since_last_gc();
1077 }
1078
1079 HeapWord*
1080 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1081 bool maximum_compaction)
1082 {
1083 const size_t region_size = ParallelCompactData::RegionSize;
1084 const ParallelCompactData& sd = summary_data();
1085
1086 const MutableSpace* const space = _space_info[id].space();
1087 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1088 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1089 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1090
1091 // Skip full regions at the beginning of the space--they are necessarily part
1092 // of the dense prefix.
1093 size_t full_count = 0;
1094 const RegionData* cp;
1095 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1096 ++full_count;
1097 }
1098
1099 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1100 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1101 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1102 if (maximum_compaction || cp == end_cp || interval_ended) {
1103 _maximum_compaction_gc_num = total_invocations();
1104 return sd.region_to_addr(cp);
1105 }
1106
1107 HeapWord* const new_top = _space_info[id].new_top();
1108 const size_t space_live = pointer_delta(new_top, space->bottom());
1109 const size_t space_used = space->used_in_words();
1110 const size_t space_capacity = space->capacity_in_words();
1111
1112 const double cur_density = double(space_live) / space_capacity;
1113 const double deadwood_density =
1114 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1115 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1116
1117 log_develop_debug(gc, compaction)(
1118 "cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1119 cur_density, deadwood_density, deadwood_goal);
1120 log_develop_debug(gc, compaction)(
1121 "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " "
1122 "space_cap=" SIZE_FORMAT,
1123 space_live, space_used,
1124 space_capacity);
1125
1126 // XXX - Use binary search?
1127 HeapWord* dense_prefix = sd.region_to_addr(cp);
1128 const RegionData* full_cp = cp;
1129 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1130 while (cp < end_cp) {
1131 HeapWord* region_destination = cp->destination();
1132 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1133
1134 log_develop_trace(gc, compaction)(
1135 "c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1136 "dp=" PTR_FORMAT " cdw=" SIZE_FORMAT_W(8),
1137 sd.region(cp), p2i(region_destination),
1138 p2i(dense_prefix), cur_deadwood);
1139
1140 if (cur_deadwood >= deadwood_goal) {
1141 // Found the region that has the correct amount of deadwood to the left.
1142 // This typically occurs after crossing a fairly sparse set of regions, so
1143 // iterate backwards over those sparse regions, looking for the region
1144 // that has the lowest density of live objects 'to the right.'
1145 size_t space_to_left = sd.region(cp) * region_size;
1146 size_t live_to_left = space_to_left - cur_deadwood;
1147 size_t space_to_right = space_capacity - space_to_left;
1148 size_t live_to_right = space_live - live_to_left;
1149 double density_to_right = double(live_to_right) / space_to_right;
1150 while (cp > full_cp) {
1151 --cp;
1152 const size_t prev_region_live_to_right = live_to_right -
1153 cp->data_size();
1154 const size_t prev_region_space_to_right = space_to_right + region_size;
1155 double prev_region_density_to_right =
1156 double(prev_region_live_to_right) / prev_region_space_to_right;
1157 if (density_to_right <= prev_region_density_to_right) {
1158 return dense_prefix;
1159 }
1160
1161 log_develop_trace(gc, compaction)(
1162 "backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1163 "pc_d2r=%10.8f",
1164 sd.region(cp), density_to_right,
1165 prev_region_density_to_right);
1166
1167 dense_prefix -= region_size;
1168 live_to_right = prev_region_live_to_right;
1169 space_to_right = prev_region_space_to_right;
1170 density_to_right = prev_region_density_to_right;
1171 }
1172 return dense_prefix;
1173 }
1174
1175 dense_prefix += region_size;
1176 ++cp;
1177 }
1178
1179 return dense_prefix;
1180 }
1181
1182 #ifndef PRODUCT
1183 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1184 const SpaceId id,
1185 const bool maximum_compaction,
1186 HeapWord* const addr)
1187 {
1188 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1189 RegionData* const cp = summary_data().region(region_idx);
1190 const MutableSpace* const space = _space_info[id].space();
1191 HeapWord* const new_top = _space_info[id].new_top();
1192
1193 const size_t space_live = pointer_delta(new_top, space->bottom());
1194 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1195 const size_t space_cap = space->capacity_in_words();
1196 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1197 const size_t live_to_right = new_top - cp->destination();
1198 const size_t dead_to_right = space->top() - addr - live_to_right;
1199
1200 log_develop_debug(gc, compaction)(
1201 "%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1202 "spl=" SIZE_FORMAT " "
1203 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1204 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT " "
1205 "ratio=%10.8f",
1206 algorithm, p2i(addr), region_idx,
1207 space_live,
1208 dead_to_left, dead_to_left_pct,
1209 dead_to_right, live_to_right,
1210 double(dead_to_right) / live_to_right);
1211 }
1212 #endif // #ifndef PRODUCT
1213
1214 // Return a fraction indicating how much of the generation can be treated as
1215 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1216 // based on the density of live objects in the generation to determine a limit,
1217 // which is then adjusted so the return value is min_percent when the density is
1218 // 1.
1219 //
1220 // The following table shows some return values for a different values of the
1221 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1222 // min_percent is 1.
1223 //
1224 // fraction allowed as dead wood
1225 // -----------------------------------------------------------------
1226 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1227 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1228 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1229 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1230 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1231 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1232 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1233 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1234 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1235 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1236 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1237 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1238 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1239 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1240 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1241 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1242 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1243 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1244 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1245 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1246 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1247 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1248 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1249
1250 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1251 {
1252 assert(_dwl_initialized, "uninitialized");
1253
1254 // The raw limit is the value of the normal distribution at x = density.
1255 const double raw_limit = normal_distribution(density);
1256
1257 // Adjust the raw limit so it becomes the minimum when the density is 1.
1258 //
1259 // First subtract the adjustment value (which is simply the precomputed value
1260 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1261 // Then add the minimum value, so the minimum is returned when the density is
1262 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1263 const double min = double(min_percent) / 100.0;
1264 const double limit = raw_limit - _dwl_adjustment + min;
1265 return MAX2(limit, 0.0);
1266 }
1267
1268 ParallelCompactData::RegionData*
1269 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1270 const RegionData* end)
1271 {
1272 const size_t region_size = ParallelCompactData::RegionSize;
1273 ParallelCompactData& sd = summary_data();
1274 size_t left = sd.region(beg);
1275 size_t right = end > beg ? sd.region(end) - 1 : left;
1276
1277 // Binary search.
1278 while (left < right) {
1279 // Equivalent to (left + right) / 2, but does not overflow.
1280 const size_t middle = left + (right - left) / 2;
1281 RegionData* const middle_ptr = sd.region(middle);
1282 HeapWord* const dest = middle_ptr->destination();
1283 HeapWord* const addr = sd.region_to_addr(middle);
1284 assert(dest != NULL, "sanity");
1285 assert(dest <= addr, "must move left");
1286
1287 if (middle > left && dest < addr) {
1288 right = middle - 1;
1289 } else if (middle < right && middle_ptr->data_size() == region_size) {
1290 left = middle + 1;
1291 } else {
1292 return middle_ptr;
1293 }
1294 }
1295 return sd.region(left);
1296 }
1297
1298 ParallelCompactData::RegionData*
1299 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1300 const RegionData* end,
1301 size_t dead_words)
1302 {
1303 ParallelCompactData& sd = summary_data();
1304 size_t left = sd.region(beg);
1305 size_t right = end > beg ? sd.region(end) - 1 : left;
1306
1307 // Binary search.
1308 while (left < right) {
1309 // Equivalent to (left + right) / 2, but does not overflow.
1310 const size_t middle = left + (right - left) / 2;
1311 RegionData* const middle_ptr = sd.region(middle);
1312 HeapWord* const dest = middle_ptr->destination();
1313 HeapWord* const addr = sd.region_to_addr(middle);
1314 assert(dest != NULL, "sanity");
1315 assert(dest <= addr, "must move left");
1316
1317 const size_t dead_to_left = pointer_delta(addr, dest);
1318 if (middle > left && dead_to_left > dead_words) {
1319 right = middle - 1;
1320 } else if (middle < right && dead_to_left < dead_words) {
1321 left = middle + 1;
1322 } else {
1323 return middle_ptr;
1324 }
1325 }
1326 return sd.region(left);
1327 }
1328
1329 // The result is valid during the summary phase, after the initial summarization
1330 // of each space into itself, and before final summarization.
1331 inline double
1332 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1333 HeapWord* const bottom,
1334 HeapWord* const top,
1335 HeapWord* const new_top)
1336 {
1337 ParallelCompactData& sd = summary_data();
1338
1339 assert(cp != NULL, "sanity");
1340 assert(bottom != NULL, "sanity");
1341 assert(top != NULL, "sanity");
1342 assert(new_top != NULL, "sanity");
1343 assert(top >= new_top, "summary data problem?");
1344 assert(new_top > bottom, "space is empty; should not be here");
1345 assert(new_top >= cp->destination(), "sanity");
1346 assert(top >= sd.region_to_addr(cp), "sanity");
1347
1348 HeapWord* const destination = cp->destination();
1349 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1350 const size_t compacted_region_live = pointer_delta(new_top, destination);
1351 const size_t compacted_region_used = pointer_delta(top,
1352 sd.region_to_addr(cp));
1353 const size_t reclaimable = compacted_region_used - compacted_region_live;
1354
1355 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1356 return double(reclaimable) / divisor;
1357 }
1358
1359 // Return the address of the end of the dense prefix, a.k.a. the start of the
1360 // compacted region. The address is always on a region boundary.
1361 //
1362 // Completely full regions at the left are skipped, since no compaction can
1363 // occur in those regions. Then the maximum amount of dead wood to allow is
1364 // computed, based on the density (amount live / capacity) of the generation;
1365 // the region with approximately that amount of dead space to the left is
1366 // identified as the limit region. Regions between the last completely full
1367 // region and the limit region are scanned and the one that has the best
1368 // (maximum) reclaimed_ratio() is selected.
1369 HeapWord*
1370 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1371 bool maximum_compaction)
1372 {
1373 const size_t region_size = ParallelCompactData::RegionSize;
1374 const ParallelCompactData& sd = summary_data();
1375
1376 const MutableSpace* const space = _space_info[id].space();
1377 HeapWord* const top = space->top();
1378 HeapWord* const top_aligned_up = sd.region_align_up(top);
1379 HeapWord* const new_top = _space_info[id].new_top();
1380 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1381 HeapWord* const bottom = space->bottom();
1382 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1383 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1384 const RegionData* const new_top_cp =
1385 sd.addr_to_region_ptr(new_top_aligned_up);
1386
1387 // Skip full regions at the beginning of the space--they are necessarily part
1388 // of the dense prefix.
1389 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1390 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1391 space->is_empty(), "no dead space allowed to the left");
1392 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1393 "region must have dead space");
1394
1395 // The gc number is saved whenever a maximum compaction is done, and used to
1396 // determine when the maximum compaction interval has expired. This avoids
1397 // successive max compactions for different reasons.
1398 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1399 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1400 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1401 total_invocations() == HeapFirstMaximumCompactionCount;
1402 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1403 _maximum_compaction_gc_num = total_invocations();
1404 return sd.region_to_addr(full_cp);
1405 }
1406
1407 const size_t space_live = pointer_delta(new_top, bottom);
1408 const size_t space_used = space->used_in_words();
1409 const size_t space_capacity = space->capacity_in_words();
1410
1411 const double density = double(space_live) / double(space_capacity);
1412 const size_t min_percent_free = MarkSweepDeadRatio;
1413 const double limiter = dead_wood_limiter(density, min_percent_free);
1414 const size_t dead_wood_max = space_used - space_live;
1415 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1416 dead_wood_max);
1417
1418 log_develop_debug(gc, compaction)(
1419 "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " "
1420 "space_cap=" SIZE_FORMAT,
1421 space_live, space_used,
1422 space_capacity);
1423 log_develop_debug(gc, compaction)(
1424 "dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1425 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1426 density, min_percent_free, limiter,
1427 dead_wood_max, dead_wood_limit);
1428
1429 // Locate the region with the desired amount of dead space to the left.
1430 const RegionData* const limit_cp =
1431 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1432
1433 // Scan from the first region with dead space to the limit region and find the
1434 // one with the best (largest) reclaimed ratio.
1435 double best_ratio = 0.0;
1436 const RegionData* best_cp = full_cp;
1437 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1438 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1439 if (tmp_ratio > best_ratio) {
1440 best_cp = cp;
1441 best_ratio = tmp_ratio;
1442 }
1443 }
1444
1445 return sd.region_to_addr(best_cp);
1446 }
1447
1448 void PSParallelCompact::summarize_spaces_quick()
1449 {
1450 for (unsigned int i = 0; i < last_space_id; ++i) {
1451 const MutableSpace* space = _space_info[i].space();
1452 HeapWord** nta = _space_info[i].new_top_addr();
1453 bool result = _summary_data.summarize(_space_info[i].split_info(),
1454 space->bottom(), space->top(), NULL,
1455 space->bottom(), space->end(), nta);
1456 assert(result, "space must fit into itself");
1457 _space_info[i].set_dense_prefix(space->bottom());
1458 }
1459 }
1460
1461 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1462 {
1463 HeapWord* const dense_prefix_end = dense_prefix(id);
1464 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1465 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1466 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1467 // Only enough dead space is filled so that any remaining dead space to the
1468 // left is larger than the minimum filler object. (The remainder is filled
1469 // during the copy/update phase.)
1470 //
1471 // The size of the dead space to the right of the boundary is not a
1472 // concern, since compaction will be able to use whatever space is
1473 // available.
1474 //
1475 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1476 // surrounds the space to be filled with an object.
1477 //
1478 // In the 32-bit VM, each bit represents two 32-bit words:
1479 // +---+
1480 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1481 // end_bits: ... x x x | 0 | || 0 x x ...
1482 // +---+
1483 //
1484 // In the 64-bit VM, each bit represents one 64-bit word:
1485 // +------------+
1486 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1487 // end_bits: ... x x 1 | 0 || 0 | x x ...
1488 // +------------+
1489 // +-------+
1490 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1491 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1492 // +-------+
1493 // +-----------+
1494 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1495 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1496 // +-----------+
1497 // +-------+
1498 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1499 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1500 // +-------+
1501
1502 // Initially assume case a, c or e will apply.
1503 size_t obj_len = CollectedHeap::min_fill_size();
1504 HeapWord* obj_beg = dense_prefix_end - obj_len;
1505
1506 #ifdef _LP64
1507 if (MinObjAlignment > 1) { // object alignment > heap word size
1508 // Cases a, c or e.
1509 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1510 // Case b above.
1511 obj_beg = dense_prefix_end - 1;
1512 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1513 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1514 // Case d above.
1515 obj_beg = dense_prefix_end - 3;
1516 obj_len = 3;
1517 }
1518 #endif // #ifdef _LP64
1519
1520 CollectedHeap::fill_with_object(obj_beg, obj_len);
1521 _mark_bitmap.mark_obj(obj_beg, obj_len);
1522 _summary_data.add_obj(obj_beg, obj_len);
1523 assert(start_array(id) != NULL, "sanity");
1524 start_array(id)->allocate_block(obj_beg);
1525 }
1526 }
1527
1528 void
1529 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1530 {
1531 assert(id < last_space_id, "id out of range");
1532 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1533 "should have been reset in summarize_spaces_quick()");
1534
1535 const MutableSpace* space = _space_info[id].space();
1536 if (_space_info[id].new_top() != space->bottom()) {
1537 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1538 _space_info[id].set_dense_prefix(dense_prefix_end);
1539
1540 #ifndef PRODUCT
1541 if (log_is_enabled(Debug, gc, compaction)) {
1542 print_dense_prefix_stats("ratio", id, maximum_compaction,
1543 dense_prefix_end);
1544 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1545 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1546 }
1547 #endif // #ifndef PRODUCT
1548
1549 // Recompute the summary data, taking into account the dense prefix. If
1550 // every last byte will be reclaimed, then the existing summary data which
1551 // compacts everything can be left in place.
1552 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1553 // If dead space crosses the dense prefix boundary, it is (at least
1554 // partially) filled with a dummy object, marked live and added to the
1555 // summary data. This simplifies the copy/update phase and must be done
1556 // before the final locations of objects are determined, to prevent
1557 // leaving a fragment of dead space that is too small to fill.
1558 fill_dense_prefix_end(id);
1559
1560 // Compute the destination of each Region, and thus each object.
1561 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1562 _summary_data.summarize(_space_info[id].split_info(),
1563 dense_prefix_end, space->top(), NULL,
1564 dense_prefix_end, space->end(),
1565 _space_info[id].new_top_addr());
1566 }
1567 }
1568
1569 if (log_develop_is_enabled(Trace, gc, compaction)) {
1570 const size_t region_size = ParallelCompactData::RegionSize;
1571 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1572 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1573 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1574 HeapWord* const new_top = _space_info[id].new_top();
1575 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1576 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1577 log_develop_trace(gc, compaction)(
1578 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1579 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1580 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1581 id, space->capacity_in_words(), p2i(dense_prefix_end),
1582 dp_region, dp_words / region_size,
1583 cr_words / region_size, p2i(new_top));
1584 }
1585 }
1586
1587 #ifndef PRODUCT
1588 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1589 HeapWord* dst_beg, HeapWord* dst_end,
1590 SpaceId src_space_id,
1591 HeapWord* src_beg, HeapWord* src_end)
1592 {
1593 log_develop_trace(gc, compaction)(
1594 "Summarizing %d [%s] into %d [%s]: "
1595 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1596 SIZE_FORMAT "-" SIZE_FORMAT " "
1597 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1598 SIZE_FORMAT "-" SIZE_FORMAT,
1599 src_space_id, space_names[src_space_id],
1600 dst_space_id, space_names[dst_space_id],
1601 p2i(src_beg), p2i(src_end),
1602 _summary_data.addr_to_region_idx(src_beg),
1603 _summary_data.addr_to_region_idx(src_end),
1604 p2i(dst_beg), p2i(dst_end),
1605 _summary_data.addr_to_region_idx(dst_beg),
1606 _summary_data.addr_to_region_idx(dst_end));
1607 }
1608 #endif // #ifndef PRODUCT
1609
1610 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1611 bool maximum_compaction)
1612 {
1613 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1614
1615 log_develop_debug(gc, marking)(
1616 "add_obj_count=" SIZE_FORMAT " "
1617 "add_obj_bytes=" SIZE_FORMAT,
1618 add_obj_count,
1619 add_obj_size * HeapWordSize);
1620 log_develop_debug(gc, marking)(
1621 "mark_bitmap_count=" SIZE_FORMAT " "
1622 "mark_bitmap_bytes=" SIZE_FORMAT,
1623 mark_bitmap_count,
1624 mark_bitmap_size * HeapWordSize);
1625
1626 // Quick summarization of each space into itself, to see how much is live.
1627 summarize_spaces_quick();
1628
1629 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1630 NOT_PRODUCT(print_region_ranges());
1631 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1632
1633 // The amount of live data that will end up in old space (assuming it fits).
1634 size_t old_space_total_live = 0;
1635 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1636 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1637 _space_info[id].space()->bottom());
1638 }
1639
1640 MutableSpace* const old_space = _space_info[old_space_id].space();
1641 const size_t old_capacity = old_space->capacity_in_words();
1642 if (old_space_total_live > old_capacity) {
1643 // XXX - should also try to expand
1644 maximum_compaction = true;
1645 }
1646
1647 // Old generations.
1648 summarize_space(old_space_id, maximum_compaction);
1649
1650 // Summarize the remaining spaces in the young gen. The initial target space
1651 // is the old gen. If a space does not fit entirely into the target, then the
1652 // remainder is compacted into the space itself and that space becomes the new
1653 // target.
1654 SpaceId dst_space_id = old_space_id;
1655 HeapWord* dst_space_end = old_space->end();
1656 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1657 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1658 const MutableSpace* space = _space_info[id].space();
1659 const size_t live = pointer_delta(_space_info[id].new_top(),
1660 space->bottom());
1661 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1662
1663 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1664 SpaceId(id), space->bottom(), space->top());)
1665 if (live > 0 && live <= available) {
1666 // All the live data will fit.
1667 bool done = _summary_data.summarize(_space_info[id].split_info(),
1668 space->bottom(), space->top(),
1669 NULL,
1670 *new_top_addr, dst_space_end,
1671 new_top_addr);
1672 assert(done, "space must fit into old gen");
1673
1674 // Reset the new_top value for the space.
1675 _space_info[id].set_new_top(space->bottom());
1676 } else if (live > 0) {
1677 // Attempt to fit part of the source space into the target space.
1678 HeapWord* next_src_addr = NULL;
1679 bool done = _summary_data.summarize(_space_info[id].split_info(),
1680 space->bottom(), space->top(),
1681 &next_src_addr,
1682 *new_top_addr, dst_space_end,
1683 new_top_addr);
1684 assert(!done, "space should not fit into old gen");
1685 assert(next_src_addr != NULL, "sanity");
1686
1687 // The source space becomes the new target, so the remainder is compacted
1688 // within the space itself.
1689 dst_space_id = SpaceId(id);
1690 dst_space_end = space->end();
1691 new_top_addr = _space_info[id].new_top_addr();
1692 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1693 space->bottom(), dst_space_end,
1694 SpaceId(id), next_src_addr, space->top());)
1695 done = _summary_data.summarize(_space_info[id].split_info(),
1696 next_src_addr, space->top(),
1697 NULL,
1698 space->bottom(), dst_space_end,
1699 new_top_addr);
1700 assert(done, "space must fit when compacted into itself");
1701 assert(*new_top_addr <= space->top(), "usage should not grow");
1702 }
1703 }
1704
1705 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1706 NOT_PRODUCT(print_region_ranges());
1707 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1708 }
1709
1710 // This method should contain all heap-specific policy for invoking a full
1711 // collection. invoke_no_policy() will only attempt to compact the heap; it
1712 // will do nothing further. If we need to bail out for policy reasons, scavenge
1713 // before full gc, or any other specialized behavior, it needs to be added here.
1714 //
1715 // Note that this method should only be called from the vm_thread while at a
1716 // safepoint.
1717 //
1718 // Note that the all_soft_refs_clear flag in the soft ref policy
1719 // may be true because this method can be called without intervening
1720 // activity. For example when the heap space is tight and full measure
1721 // are being taken to free space.
1722 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1723 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1724 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1725 "should be in vm thread");
1726
1727 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1728 GCCause::Cause gc_cause = heap->gc_cause();
1729 assert(!heap->is_gc_active(), "not reentrant");
1730
1731 PSAdaptiveSizePolicy* policy = heap->size_policy();
1732 IsGCActiveMark mark;
1733
1734 if (ScavengeBeforeFullGC) {
1735 PSScavenge::invoke_no_policy();
1736 }
1737
1738 const bool clear_all_soft_refs =
1739 heap->soft_ref_policy()->should_clear_all_soft_refs();
1740
1741 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1742 maximum_heap_compaction);
1743 }
1744
1745 // This method contains no policy. You should probably
1746 // be calling invoke() instead.
1747 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1748 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1749 assert(ref_processor() != NULL, "Sanity");
1750
1751 if (GCLocker::check_active_before_gc()) {
1752 return false;
1753 }
1754
1755 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1756
1757 GCIdMark gc_id_mark;
1758 _gc_timer.register_gc_start();
1759 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1760
1761 TimeStamp marking_start;
1762 TimeStamp compaction_start;
1763 TimeStamp collection_exit;
1764
1765 GCCause::Cause gc_cause = heap->gc_cause();
1766 PSYoungGen* young_gen = heap->young_gen();
1767 PSOldGen* old_gen = heap->old_gen();
1768 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1769
1770 // The scope of casr should end after code that can change
1771 // SoftRefPolicy::_should_clear_all_soft_refs.
1772 ClearedAllSoftRefs casr(maximum_heap_compaction,
1773 heap->soft_ref_policy());
1774
1775 if (ZapUnusedHeapArea) {
1776 // Save information needed to minimize mangling
1777 heap->record_gen_tops_before_GC();
1778 }
1779
1780 // Make sure data structures are sane, make the heap parsable, and do other
1781 // miscellaneous bookkeeping.
1782 pre_compact();
1783
1784 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
1785
1786 // Get the compaction manager reserved for the VM thread.
1787 ParCompactionManager* const vmthread_cm =
1788 ParCompactionManager::manager_array(ParallelScavengeHeap::heap()->workers().total_workers());
1789
1790 {
1791 ResourceMark rm;
1792 HandleMark hm;
1793
1794 const uint active_workers =
1795 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().total_workers(),
1796 ParallelScavengeHeap::heap()->workers().active_workers(),
1797 Threads::number_of_non_daemon_threads());
1798 ParallelScavengeHeap::heap()->workers().update_active_workers(active_workers);
1799
1800 GCTraceCPUTime tcpu;
1801 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1802
1803 heap->pre_full_gc_dump(&_gc_timer);
1804
1805 TraceCollectorStats tcs(counters());
1806 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause);
1807
1808 if (log_is_enabled(Debug, gc, heap, exit)) {
1809 accumulated_time()->start();
1810 }
1811
1812 // Let the size policy know we're starting
1813 size_policy->major_collection_begin();
1814
1815 #if COMPILER2_OR_JVMCI
1816 DerivedPointerTable::clear();
1817 #endif
1818
1819 ref_processor()->enable_discovery();
1820 ref_processor()->setup_policy(maximum_heap_compaction);
1821
1822 bool marked_for_unloading = false;
1823
1824 marking_start.update();
1825 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1826
1827 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1828 && GCCause::is_user_requested_gc(gc_cause);
1829 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1830
1831 #if COMPILER2_OR_JVMCI
1832 assert(DerivedPointerTable::is_active(), "Sanity");
1833 DerivedPointerTable::set_active(false);
1834 #endif
1835
1836 // adjust_roots() updates Universe::_intArrayKlassObj which is
1837 // needed by the compaction for filling holes in the dense prefix.
1838 adjust_roots(vmthread_cm);
1839
1840 compaction_start.update();
1841 compact();
1842
1843 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1844 // done before resizing.
1845 post_compact();
1846
1847 // Let the size policy know we're done
1848 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1849
1850 if (UseAdaptiveSizePolicy) {
1851 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1852 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1853 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1854
1855 // Don't check if the size_policy is ready here. Let
1856 // the size_policy check that internally.
1857 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1858 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1859 // Swap the survivor spaces if from_space is empty. The
1860 // resize_young_gen() called below is normally used after
1861 // a successful young GC and swapping of survivor spaces;
1862 // otherwise, it will fail to resize the young gen with
1863 // the current implementation.
1864 if (young_gen->from_space()->is_empty()) {
1865 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1866 young_gen->swap_spaces();
1867 }
1868
1869 // Calculate optimal free space amounts
1870 assert(young_gen->max_gen_size() >
1871 young_gen->from_space()->capacity_in_bytes() +
1872 young_gen->to_space()->capacity_in_bytes(),
1873 "Sizes of space in young gen are out-of-bounds");
1874
1875 size_t young_live = young_gen->used_in_bytes();
1876 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1877 size_t old_live = old_gen->used_in_bytes();
1878 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1879 size_t max_old_gen_size = old_gen->max_gen_size();
1880 size_t max_eden_size = young_gen->max_gen_size() -
1881 young_gen->from_space()->capacity_in_bytes() -
1882 young_gen->to_space()->capacity_in_bytes();
1883
1884 // Used for diagnostics
1885 size_policy->clear_generation_free_space_flags();
1886
1887 size_policy->compute_generations_free_space(young_live,
1888 eden_live,
1889 old_live,
1890 cur_eden,
1891 max_old_gen_size,
1892 max_eden_size,
1893 true /* full gc*/);
1894
1895 size_policy->check_gc_overhead_limit(eden_live,
1896 max_old_gen_size,
1897 max_eden_size,
1898 true /* full gc*/,
1899 gc_cause,
1900 heap->soft_ref_policy());
1901
1902 size_policy->decay_supplemental_growth(true /* full gc*/);
1903
1904 heap->resize_old_gen(
1905 size_policy->calculated_old_free_size_in_bytes());
1906
1907 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1908 size_policy->calculated_survivor_size_in_bytes());
1909 }
1910
1911 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1912 }
1913
1914 if (UsePerfData) {
1915 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1916 counters->update_counters();
1917 counters->update_old_capacity(old_gen->capacity_in_bytes());
1918 counters->update_young_capacity(young_gen->capacity_in_bytes());
1919 }
1920
1921 heap->resize_all_tlabs();
1922
1923 // Resize the metaspace capacity after a collection
1924 MetaspaceGC::compute_new_size();
1925
1926 if (log_is_enabled(Debug, gc, heap, exit)) {
1927 accumulated_time()->stop();
1928 }
1929
1930 heap->print_heap_change(pre_gc_values);
1931
1932 // Track memory usage and detect low memory
1933 MemoryService::track_memory_usage();
1934 heap->update_counters();
1935
1936 heap->post_full_gc_dump(&_gc_timer);
1937 }
1938
1939 #ifdef ASSERT
1940 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1941 ParCompactionManager* const cm =
1942 ParCompactionManager::manager_array(int(i));
1943 assert(cm->marking_stack()->is_empty(), "should be empty");
1944 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1945 }
1946 #endif // ASSERT
1947
1948 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1949 HandleMark hm; // Discard invalid handles created during verification
1950 Universe::verify("After GC");
1951 }
1952
1953 // Re-verify object start arrays
1954 if (VerifyObjectStartArray &&
1955 VerifyAfterGC) {
1956 old_gen->verify_object_start_array();
1957 }
1958
1959 if (ZapUnusedHeapArea) {
1960 old_gen->object_space()->check_mangled_unused_area_complete();
1961 }
1962
1963 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1964
1965 collection_exit.update();
1966
1967 heap->print_heap_after_gc();
1968 heap->trace_heap_after_gc(&_gc_tracer);
1969
1970 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1971 marking_start.ticks(), compaction_start.ticks(),
1972 collection_exit.ticks());
1973
1974 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1975
1976 _gc_timer.register_gc_end();
1977
1978 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1979 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1980
1981 return true;
1982 }
1983
1984 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1985 private:
1986 uint _worker_id;
1987
1988 public:
1989 PCAddThreadRootsMarkingTaskClosure(uint worker_id) : _worker_id(worker_id) { }
1990 void do_thread(Thread* thread) {
1991 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
1992
1993 ResourceMark rm;
1994
1995 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(_worker_id);
1996
1997 PCMarkAndPushClosure mark_and_push_closure(cm);
1998 MarkingCodeBlobClosure mark_and_push_in_blobs(&mark_and_push_closure, !CodeBlobToOopClosure::FixRelocations);
1999
2000 thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs);
2001
2002 // Do the real work
2003 cm->follow_marking_stacks();
2004 }
2005 };
2006
2007 static void mark_from_roots_work(ParallelRootType::Value root_type, uint worker_id) {
2008 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2009
2010 ParCompactionManager* cm =
2011 ParCompactionManager::gc_thread_compaction_manager(worker_id);
2012 PCMarkAndPushClosure mark_and_push_closure(cm);
2013
2014 switch (root_type) {
2015 case ParallelRootType::universe:
2016 Universe::oops_do(&mark_and_push_closure);
2017 break;
2018
2019 case ParallelRootType::object_synchronizer:
2020 ObjectSynchronizer::oops_do(&mark_and_push_closure);
2021 break;
2022
2023 case ParallelRootType::management:
2024 Management::oops_do(&mark_and_push_closure);
2025 break;
2026
2027 case ParallelRootType::jvmti:
2028 JvmtiExport::oops_do(&mark_and_push_closure);
2029 break;
2030
2031 case ParallelRootType::class_loader_data:
2032 {
2033 CLDToOopClosure cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_strong);
2034 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
2035 }
2036 break;
2037
2038 case ParallelRootType::code_cache:
2039 // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
2040 //ScavengableNMethods::scavengable_nmethods_do(CodeBlobToOopClosure(&mark_and_push_closure));
2041 AOTLoader::oops_do(&mark_and_push_closure);
2042 break;
2043
2044 case ParallelRootType::sentinel:
2045 DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds
2046 fatal("Bad enumeration value: %u", root_type);
2047 break;
2048 }
2049
2050 // Do the real work
2051 cm->follow_marking_stacks();
2052 }
2053
2054 static void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
2055 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2056
2057 ParCompactionManager* cm =
2058 ParCompactionManager::gc_thread_compaction_manager(worker_id);
2059
2060 oop obj = NULL;
2061 ObjArrayTask task;
2062 do {
2063 while (ParCompactionManager::steal_objarray(worker_id, task)) {
2064 cm->follow_array((objArrayOop)task.obj(), task.index());
2065 cm->follow_marking_stacks();
2066 }
2067 while (ParCompactionManager::steal(worker_id, obj)) {
2068 cm->follow_contents(obj);
2069 cm->follow_marking_stacks();
2070 }
2071 } while (!terminator.offer_termination());
2072 }
2073
2074 class MarkFromRootsTask : public AbstractGangTask {
2075 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
2076 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
2077 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
2078 SequentialSubTasksDone _subtasks;
2079 TaskTerminator _terminator;
2080 uint _active_workers;
2081
2082 public:
2083 MarkFromRootsTask(uint active_workers) :
2084 AbstractGangTask("MarkFromRootsTask"),
2085 _strong_roots_scope(active_workers),
2086 _subtasks(),
2087 _terminator(active_workers, ParCompactionManager::oop_task_queues()),
2088 _active_workers(active_workers) {
2089 _subtasks.set_n_threads(active_workers);
2090 _subtasks.set_n_tasks(ParallelRootType::sentinel);
2091 }
2092
2093 virtual void work(uint worker_id) {
2094 for (uint task = 0; _subtasks.try_claim_task(task); /*empty*/ ) {
2095 mark_from_roots_work(static_cast<ParallelRootType::Value>(task), worker_id);
2096 }
2097 _subtasks.all_tasks_completed();
2098
2099 PCAddThreadRootsMarkingTaskClosure closure(worker_id);
2100 Threads::possibly_parallel_threads_do(true /*parallel */, &closure);
2101
2102 // Mark from OopStorages
2103 {
2104 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2105 PCMarkAndPushClosure closure(cm);
2106 _oop_storage_set_par_state.oops_do(&closure);
2107 // Do the real work
2108 cm->follow_marking_stacks();
2109 }
2110
2111 if (_active_workers > 1) {
2112 steal_marking_work(_terminator, worker_id);
2113 }
2114 }
2115 };
2116
2117 class PCRefProcTask : public AbstractGangTask {
2118 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
2119 ProcessTask& _task;
2120 uint _ergo_workers;
2121 TaskTerminator _terminator;
2122
2123 public:
2124 PCRefProcTask(ProcessTask& task, uint ergo_workers) :
2125 AbstractGangTask("PCRefProcTask"),
2126 _task(task),
2127 _ergo_workers(ergo_workers),
2128 _terminator(_ergo_workers, ParCompactionManager::oop_task_queues()) {
2129 }
2130
2131 virtual void work(uint worker_id) {
2132 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2133 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2134
2135 ParCompactionManager* cm =
2136 ParCompactionManager::gc_thread_compaction_manager(worker_id);
2137 PCMarkAndPushClosure mark_and_push_closure(cm);
2138 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2139 _task.work(worker_id, *PSParallelCompact::is_alive_closure(),
2140 mark_and_push_closure, follow_stack_closure);
2141
2142 steal_marking_work(_terminator, worker_id);
2143 }
2144 };
2145
2146 class RefProcTaskExecutor: public AbstractRefProcTaskExecutor {
2147 void execute(ProcessTask& process_task, uint ergo_workers) {
2148 assert(ParallelScavengeHeap::heap()->workers().active_workers() == ergo_workers,
2149 "Ergonomically chosen workers (%u) must be equal to active workers (%u)",
2150 ergo_workers, ParallelScavengeHeap::heap()->workers().active_workers());
2151
2152 PCRefProcTask task(process_task, ergo_workers);
2153 ParallelScavengeHeap::heap()->workers().run_task(&task);
2154 }
2155 };
2156
2157 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2158 bool maximum_heap_compaction,
2159 ParallelOldTracer *gc_tracer) {
2160 // Recursively traverse all live objects and mark them
2161 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2162
2163 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2164 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2165
2166 PCMarkAndPushClosure mark_and_push_closure(cm);
2167 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2168
2169 // Need new claim bits before marking starts.
2170 ClassLoaderDataGraph::clear_claimed_marks();
2171
2172 {
2173 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2174
2175 MarkFromRootsTask task(active_gc_threads);
2176 ParallelScavengeHeap::heap()->workers().run_task(&task);
2177 }
2178
2179 // Process reference objects found during marking
2180 {
2181 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2182
2183 ReferenceProcessorStats stats;
2184 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
2185
2186 if (ref_processor()->processing_is_mt()) {
2187 ref_processor()->set_active_mt_degree(active_gc_threads);
2188
2189 RefProcTaskExecutor task_executor;
2190 stats = ref_processor()->process_discovered_references(
2191 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2192 &task_executor, &pt);
2193 } else {
2194 stats = ref_processor()->process_discovered_references(
2195 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2196 &pt);
2197 }
2198
2199 gc_tracer->report_gc_reference_stats(stats);
2200 pt.print_all_references();
2201 }
2202
2203 // This is the point where the entire marking should have completed.
2204 assert(cm->marking_stacks_empty(), "Marking should have completed");
2205
2206 {
2207 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
2208 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
2209 }
2210
2211 {
2212 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2213
2214 // Follow system dictionary roots and unload classes.
2215 bool purged_class = SystemDictionary::do_unloading(&_gc_timer);
2216
2217 // Unload nmethods.
2218 CodeCache::do_unloading(is_alive_closure(), purged_class);
2219
2220 // Prune dead klasses from subklass/sibling/implementor lists.
2221 Klass::clean_weak_klass_links(purged_class);
2222
2223 // Clean JVMCI metadata handles.
2224 JVMCI_ONLY(JVMCI::do_unloading(purged_class));
2225 }
2226
2227 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2228 }
2229
2230 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2231 // Adjust the pointers to reflect the new locations
2232 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2233
2234 // Need new claim bits when tracing through and adjusting pointers.
2235 ClassLoaderDataGraph::clear_claimed_marks();
2236
2237 PCAdjustPointerClosure oop_closure(cm);
2238
2239 // General strong roots.
2240 Universe::oops_do(&oop_closure);
2241 Threads::oops_do(&oop_closure, NULL);
2242 ObjectSynchronizer::oops_do(&oop_closure);
2243 Management::oops_do(&oop_closure);
2244 JvmtiExport::oops_do(&oop_closure);
2245 OopStorageSet::strong_oops_do(&oop_closure);
2246 CLDToOopClosure cld_closure(&oop_closure, ClassLoaderData::_claim_strong);
2247 ClassLoaderDataGraph::cld_do(&cld_closure);
2248
2249 // Now adjust pointers in remaining weak roots. (All of which should
2250 // have been cleared if they pointed to non-surviving objects.)
2251 WeakProcessor::oops_do(&oop_closure);
2252
2253 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2254 CodeCache::blobs_do(&adjust_from_blobs);
2255 AOT_ONLY(AOTLoader::oops_do(&oop_closure);)
2256
2257 ref_processor()->weak_oops_do(&oop_closure);
2258 // Roots were visited so references into the young gen in roots
2259 // may have been scanned. Process them also.
2260 // Should the reference processor have a span that excludes
2261 // young gen objects?
2262 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2263 }
2264
2265 // Helper class to print 8 region numbers per line and then print the total at the end.
2266 class FillableRegionLogger : public StackObj {
2267 private:
2268 Log(gc, compaction) log;
2269 static const int LineLength = 8;
2270 size_t _regions[LineLength];
2271 int _next_index;
2272 bool _enabled;
2273 size_t _total_regions;
2274 public:
2275 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
2276 ~FillableRegionLogger() {
2277 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2278 }
2279
2280 void print_line() {
2281 if (!_enabled || _next_index == 0) {
2282 return;
2283 }
2284 FormatBuffer<> line("Fillable: ");
2285 for (int i = 0; i < _next_index; i++) {
2286 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2287 }
2288 log.trace("%s", line.buffer());
2289 _next_index = 0;
2290 }
2291
2292 void handle(size_t region) {
2293 if (!_enabled) {
2294 return;
2295 }
2296 _regions[_next_index++] = region;
2297 if (_next_index == LineLength) {
2298 print_line();
2299 }
2300 _total_regions++;
2301 }
2302 };
2303
2304 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
2305 {
2306 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2307
2308 // Find the threads that are active
2309 uint worker_id = 0;
2310
2311 // Find all regions that are available (can be filled immediately) and
2312 // distribute them to the thread stacks. The iteration is done in reverse
2313 // order (high to low) so the regions will be removed in ascending order.
2314
2315 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2316
2317 // id + 1 is used to test termination so unsigned can
2318 // be used with an old_space_id == 0.
2319 FillableRegionLogger region_logger;
2320 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2321 SpaceInfo* const space_info = _space_info + id;
2322 MutableSpace* const space = space_info->space();
2323 HeapWord* const new_top = space_info->new_top();
2324
2325 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2326 const size_t end_region =
2327 sd.addr_to_region_idx(sd.region_align_up(new_top));
2328
2329 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2330 if (sd.region(cur)->claim_unsafe()) {
2331 ParCompactionManager* cm = ParCompactionManager::manager_array(worker_id);
2332 bool result = sd.region(cur)->mark_normal();
2333 assert(result, "Must succeed at this point.");
2334 cm->region_stack()->push(cur);
2335 region_logger.handle(cur);
2336 // Assign regions to tasks in round-robin fashion.
2337 if (++worker_id == parallel_gc_threads) {
2338 worker_id = 0;
2339 }
2340 }
2341 }
2342 region_logger.print_line();
2343 }
2344 }
2345
2346 class TaskQueue : StackObj {
2347 volatile uint _counter;
2348 uint _size;
2349 uint _insert_index;
2350 PSParallelCompact::UpdateDensePrefixTask* _backing_array;
2351 public:
2352 explicit TaskQueue(uint size) : _counter(0), _size(size), _insert_index(0), _backing_array(NULL) {
2353 _backing_array = NEW_C_HEAP_ARRAY(PSParallelCompact::UpdateDensePrefixTask, _size, mtGC);
2354 }
2355 ~TaskQueue() {
2356 assert(_counter >= _insert_index, "not all queue elements were claimed");
2357 FREE_C_HEAP_ARRAY(T, _backing_array);
2358 }
2359
2360 void push(const PSParallelCompact::UpdateDensePrefixTask& value) {
2361 assert(_insert_index < _size, "too small backing array");
2362 _backing_array[_insert_index++] = value;
2363 }
2364
2365 bool try_claim(PSParallelCompact::UpdateDensePrefixTask& reference) {
2366 uint claimed = Atomic::fetch_and_add(&_counter, 1u);
2367 if (claimed < _insert_index) {
2368 reference = _backing_array[claimed];
2369 return true;
2370 } else {
2371 return false;
2372 }
2373 }
2374 };
2375
2376 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2377
2378 void PSParallelCompact::enqueue_dense_prefix_tasks(TaskQueue& task_queue,
2379 uint parallel_gc_threads) {
2380 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2381
2382 ParallelCompactData& sd = PSParallelCompact::summary_data();
2383
2384 // Iterate over all the spaces adding tasks for updating
2385 // regions in the dense prefix. Assume that 1 gc thread
2386 // will work on opening the gaps and the remaining gc threads
2387 // will work on the dense prefix.
2388 unsigned int space_id;
2389 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2390 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2391 const MutableSpace* const space = _space_info[space_id].space();
2392
2393 if (dense_prefix_end == space->bottom()) {
2394 // There is no dense prefix for this space.
2395 continue;
2396 }
2397
2398 // The dense prefix is before this region.
2399 size_t region_index_end_dense_prefix =
2400 sd.addr_to_region_idx(dense_prefix_end);
2401 RegionData* const dense_prefix_cp =
2402 sd.region(region_index_end_dense_prefix);
2403 assert(dense_prefix_end == space->end() ||
2404 dense_prefix_cp->available() ||
2405 dense_prefix_cp->claimed(),
2406 "The region after the dense prefix should always be ready to fill");
2407
2408 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2409
2410 // Is there dense prefix work?
2411 size_t total_dense_prefix_regions =
2412 region_index_end_dense_prefix - region_index_start;
2413 // How many regions of the dense prefix should be given to
2414 // each thread?
2415 if (total_dense_prefix_regions > 0) {
2416 uint tasks_for_dense_prefix = 1;
2417 if (total_dense_prefix_regions <=
2418 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2419 // Don't over partition. This assumes that
2420 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2421 // so there are not many regions to process.
2422 tasks_for_dense_prefix = parallel_gc_threads;
2423 } else {
2424 // Over partition
2425 tasks_for_dense_prefix = parallel_gc_threads *
2426 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2427 }
2428 size_t regions_per_thread = total_dense_prefix_regions /
2429 tasks_for_dense_prefix;
2430 // Give each thread at least 1 region.
2431 if (regions_per_thread == 0) {
2432 regions_per_thread = 1;
2433 }
2434
2435 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2436 if (region_index_start >= region_index_end_dense_prefix) {
2437 break;
2438 }
2439 // region_index_end is not processed
2440 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2441 region_index_end_dense_prefix);
2442 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
2443 region_index_start,
2444 region_index_end));
2445 region_index_start = region_index_end;
2446 }
2447 }
2448 // This gets any part of the dense prefix that did not
2449 // fit evenly.
2450 if (region_index_start < region_index_end_dense_prefix) {
2451 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
2452 region_index_start,
2453 region_index_end_dense_prefix));
2454 }
2455 }
2456 }
2457
2458 #ifdef ASSERT
2459 // Write a histogram of the number of times the block table was filled for a
2460 // region.
2461 void PSParallelCompact::write_block_fill_histogram()
2462 {
2463 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2464 return;
2465 }
2466
2467 Log(gc, compaction) log;
2468 ResourceMark rm;
2469 LogStream ls(log.trace());
2470 outputStream* out = &ls;
2471
2472 typedef ParallelCompactData::RegionData rd_t;
2473 ParallelCompactData& sd = summary_data();
2474
2475 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2476 MutableSpace* const spc = _space_info[id].space();
2477 if (spc->bottom() != spc->top()) {
2478 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2479 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2480 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2481
2482 size_t histo[5] = { 0, 0, 0, 0, 0 };
2483 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2484 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2485
2486 for (const rd_t* cur = beg; cur < end; ++cur) {
2487 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2488 }
2489 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2490 for (size_t i = 0; i < histo_len; ++i) {
2491 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2492 histo[i], 100.0 * histo[i] / region_cnt);
2493 }
2494 out->cr();
2495 }
2496 }
2497 }
2498 #endif // #ifdef ASSERT
2499
2500 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
2501 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2502
2503 ParCompactionManager* cm =
2504 ParCompactionManager::gc_thread_compaction_manager(worker_id);
2505
2506 // Drain the stacks that have been preloaded with regions
2507 // that are ready to fill.
2508
2509 cm->drain_region_stacks();
2510
2511 guarantee(cm->region_stack()->is_empty(), "Not empty");
2512
2513 size_t region_index = 0;
2514
2515 while (true) {
2516 if (ParCompactionManager::steal(worker_id, region_index)) {
2517 PSParallelCompact::fill_and_update_region(cm, region_index);
2518 cm->drain_region_stacks();
2519 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
2520 // Fill and update an unavailable region with the help of a shadow region
2521 PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
2522 cm->drain_region_stacks();
2523 } else {
2524 if (terminator->offer_termination()) {
2525 break;
2526 }
2527 // Go around again.
2528 }
2529 }
2530 return;
2531 }
2532
2533 class UpdateDensePrefixAndCompactionTask: public AbstractGangTask {
2534 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
2535 TaskQueue& _tq;
2536 TaskTerminator _terminator;
2537 uint _active_workers;
2538
2539 public:
2540 UpdateDensePrefixAndCompactionTask(TaskQueue& tq, uint active_workers) :
2541 AbstractGangTask("UpdateDensePrefixAndCompactionTask"),
2542 _tq(tq),
2543 _terminator(active_workers, ParCompactionManager::region_task_queues()),
2544 _active_workers(active_workers) {
2545 }
2546 virtual void work(uint worker_id) {
2547 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2548
2549 for (PSParallelCompact::UpdateDensePrefixTask task; _tq.try_claim(task); /* empty */) {
2550 PSParallelCompact::update_and_deadwood_in_dense_prefix(cm,
2551 task._space_id,
2552 task._region_index_start,
2553 task._region_index_end);
2554 }
2555
2556 // Once a thread has drained it's stack, it should try to steal regions from
2557 // other threads.
2558 compaction_with_stealing_work(&_terminator, worker_id);
2559 }
2560 };
2561
2562 void PSParallelCompact::compact() {
2563 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2564
2565 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2566 PSOldGen* old_gen = heap->old_gen();
2567 old_gen->start_array()->reset();
2568 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2569
2570 // for [0..last_space_id)
2571 // for [0..active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)
2572 // push
2573 // push
2574 //
2575 // max push count is thus: last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1)
2576 TaskQueue task_queue(last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1));
2577 initialize_shadow_regions(active_gc_threads);
2578 prepare_region_draining_tasks(active_gc_threads);
2579 enqueue_dense_prefix_tasks(task_queue, active_gc_threads);
2580
2581 {
2582 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2583
2584 UpdateDensePrefixAndCompactionTask task(task_queue, active_gc_threads);
2585 ParallelScavengeHeap::heap()->workers().run_task(&task);
2586
2587 #ifdef ASSERT
2588 // Verify that all regions have been processed before the deferred updates.
2589 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2590 verify_complete(SpaceId(id));
2591 }
2592 #endif
2593 }
2594
2595 {
2596 // Update the deferred objects, if any. Any compaction manager can be used.
2597 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2598 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2599 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2600 update_deferred_objects(cm, SpaceId(id));
2601 }
2602 }
2603
2604 DEBUG_ONLY(write_block_fill_histogram());
2605 }
2606
2607 #ifdef ASSERT
2608 void PSParallelCompact::verify_complete(SpaceId space_id) {
2609 // All Regions between space bottom() to new_top() should be marked as filled
2610 // and all Regions between new_top() and top() should be available (i.e.,
2611 // should have been emptied).
2612 ParallelCompactData& sd = summary_data();
2613 SpaceInfo si = _space_info[space_id];
2614 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2615 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2616 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2617 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2618 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2619
2620 bool issued_a_warning = false;
2621
2622 size_t cur_region;
2623 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2624 const RegionData* const c = sd.region(cur_region);
2625 if (!c->completed()) {
2626 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2627 cur_region, c->destination_count());
2628 issued_a_warning = true;
2629 }
2630 }
2631
2632 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2633 const RegionData* const c = sd.region(cur_region);
2634 if (!c->available()) {
2635 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2636 cur_region, c->destination_count());
2637 issued_a_warning = true;
2638 }
2639 }
2640
2641 if (issued_a_warning) {
2642 print_region_ranges();
2643 }
2644 }
2645 #endif // #ifdef ASSERT
2646
2647 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2648 _start_array->allocate_block(addr);
2649 compaction_manager()->update_contents(oop(addr));
2650 }
2651
2652 // Update interior oops in the ranges of regions [beg_region, end_region).
2653 void
2654 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2655 SpaceId space_id,
2656 size_t beg_region,
2657 size_t end_region) {
2658 ParallelCompactData& sd = summary_data();
2659 ParMarkBitMap* const mbm = mark_bitmap();
2660
2661 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2662 HeapWord* const end_addr = sd.region_to_addr(end_region);
2663 assert(beg_region <= end_region, "bad region range");
2664 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2665
2666 #ifdef ASSERT
2667 // Claim the regions to avoid triggering an assert when they are marked as
2668 // filled.
2669 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2670 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2671 }
2672 #endif // #ifdef ASSERT
2673
2674 if (beg_addr != space(space_id)->bottom()) {
2675 // Find the first live object or block of dead space that *starts* in this
2676 // range of regions. If a partial object crosses onto the region, skip it;
2677 // it will be marked for 'deferred update' when the object head is
2678 // processed. If dead space crosses onto the region, it is also skipped; it
2679 // will be filled when the prior region is processed. If neither of those
2680 // apply, the first word in the region is the start of a live object or dead
2681 // space.
2682 assert(beg_addr > space(space_id)->bottom(), "sanity");
2683 const RegionData* const cp = sd.region(beg_region);
2684 if (cp->partial_obj_size() != 0) {
2685 beg_addr = sd.partial_obj_end(beg_region);
2686 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2687 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2688 }
2689 }
2690
2691 if (beg_addr < end_addr) {
2692 // A live object or block of dead space starts in this range of Regions.
2693 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2694
2695 // Create closures and iterate.
2696 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2697 FillClosure fill_closure(cm, space_id);
2698 ParMarkBitMap::IterationStatus status;
2699 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2700 dense_prefix_end);
2701 if (status == ParMarkBitMap::incomplete) {
2702 update_closure.do_addr(update_closure.source());
2703 }
2704 }
2705
2706 // Mark the regions as filled.
2707 RegionData* const beg_cp = sd.region(beg_region);
2708 RegionData* const end_cp = sd.region(end_region);
2709 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2710 cp->set_completed();
2711 }
2712 }
2713
2714 // Return the SpaceId for the space containing addr. If addr is not in the
2715 // heap, last_space_id is returned. In debug mode it expects the address to be
2716 // in the heap and asserts such.
2717 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2718 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2719
2720 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2721 if (_space_info[id].space()->contains(addr)) {
2722 return SpaceId(id);
2723 }
2724 }
2725
2726 assert(false, "no space contains the addr");
2727 return last_space_id;
2728 }
2729
2730 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2731 SpaceId id) {
2732 assert(id < last_space_id, "bad space id");
2733
2734 ParallelCompactData& sd = summary_data();
2735 const SpaceInfo* const space_info = _space_info + id;
2736 ObjectStartArray* const start_array = space_info->start_array();
2737
2738 const MutableSpace* const space = space_info->space();
2739 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2740 HeapWord* const beg_addr = space_info->dense_prefix();
2741 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2742
2743 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2744 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2745 const RegionData* cur_region;
2746 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2747 HeapWord* const addr = cur_region->deferred_obj_addr();
2748 if (addr != NULL) {
2749 if (start_array != NULL) {
2750 start_array->allocate_block(addr);
2751 }
2752 cm->update_contents(oop(addr));
2753 assert(oopDesc::is_oop_or_null(oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2754 }
2755 }
2756 }
2757
2758 // Skip over count live words starting from beg, and return the address of the
2759 // next live word. Unless marked, the word corresponding to beg is assumed to
2760 // be dead. Callers must either ensure beg does not correspond to the middle of
2761 // an object, or account for those live words in some other way. Callers must
2762 // also ensure that there are enough live words in the range [beg, end) to skip.
2763 HeapWord*
2764 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2765 {
2766 assert(count > 0, "sanity");
2767
2768 ParMarkBitMap* m = mark_bitmap();
2769 idx_t bits_to_skip = m->words_to_bits(count);
2770 idx_t cur_beg = m->addr_to_bit(beg);
2771 const idx_t search_end = m->align_range_end(m->addr_to_bit(end));
2772
2773 do {
2774 cur_beg = m->find_obj_beg(cur_beg, search_end);
2775 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2776 const size_t obj_bits = cur_end - cur_beg + 1;
2777 if (obj_bits > bits_to_skip) {
2778 return m->bit_to_addr(cur_beg + bits_to_skip);
2779 }
2780 bits_to_skip -= obj_bits;
2781 cur_beg = cur_end + 1;
2782 } while (bits_to_skip > 0);
2783
2784 // Skipping the desired number of words landed just past the end of an object.
2785 // Find the start of the next object.
2786 cur_beg = m->find_obj_beg(cur_beg, search_end);
2787 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2788 return m->bit_to_addr(cur_beg);
2789 }
2790
2791 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2792 SpaceId src_space_id,
2793 size_t src_region_idx)
2794 {
2795 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2796
2797 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2798 if (split_info.dest_region_addr() == dest_addr) {
2799 // The partial object ending at the split point contains the first word to
2800 // be copied to dest_addr.
2801 return split_info.first_src_addr();
2802 }
2803
2804 const ParallelCompactData& sd = summary_data();
2805 ParMarkBitMap* const bitmap = mark_bitmap();
2806 const size_t RegionSize = ParallelCompactData::RegionSize;
2807
2808 assert(sd.is_region_aligned(dest_addr), "not aligned");
2809 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2810 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2811 HeapWord* const src_region_destination = src_region_ptr->destination();
2812
2813 assert(dest_addr >= src_region_destination, "wrong src region");
2814 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2815
2816 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2817 HeapWord* const src_region_end = src_region_beg + RegionSize;
2818
2819 HeapWord* addr = src_region_beg;
2820 if (dest_addr == src_region_destination) {
2821 // Return the first live word in the source region.
2822 if (partial_obj_size == 0) {
2823 addr = bitmap->find_obj_beg(addr, src_region_end);
2824 assert(addr < src_region_end, "no objects start in src region");
2825 }
2826 return addr;
2827 }
2828
2829 // Must skip some live data.
2830 size_t words_to_skip = dest_addr - src_region_destination;
2831 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2832
2833 if (partial_obj_size >= words_to_skip) {
2834 // All the live words to skip are part of the partial object.
2835 addr += words_to_skip;
2836 if (partial_obj_size == words_to_skip) {
2837 // Find the first live word past the partial object.
2838 addr = bitmap->find_obj_beg(addr, src_region_end);
2839 assert(addr < src_region_end, "wrong src region");
2840 }
2841 return addr;
2842 }
2843
2844 // Skip over the partial object (if any).
2845 if (partial_obj_size != 0) {
2846 words_to_skip -= partial_obj_size;
2847 addr += partial_obj_size;
2848 }
2849
2850 // Skip over live words due to objects that start in the region.
2851 addr = skip_live_words(addr, src_region_end, words_to_skip);
2852 assert(addr < src_region_end, "wrong src region");
2853 return addr;
2854 }
2855
2856 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2857 SpaceId src_space_id,
2858 size_t beg_region,
2859 HeapWord* end_addr)
2860 {
2861 ParallelCompactData& sd = summary_data();
2862
2863 #ifdef ASSERT
2864 MutableSpace* const src_space = _space_info[src_space_id].space();
2865 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2866 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2867 "src_space_id does not match beg_addr");
2868 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2869 "src_space_id does not match end_addr");
2870 #endif // #ifdef ASSERT
2871
2872 RegionData* const beg = sd.region(beg_region);
2873 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2874
2875 // Regions up to new_top() are enqueued if they become available.
2876 HeapWord* const new_top = _space_info[src_space_id].new_top();
2877 RegionData* const enqueue_end =
2878 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2879
2880 for (RegionData* cur = beg; cur < end; ++cur) {
2881 assert(cur->data_size() > 0, "region must have live data");
2882 cur->decrement_destination_count();
2883 if (cur < enqueue_end && cur->available() && cur->claim()) {
2884 if (cur->mark_normal()) {
2885 cm->push_region(sd.region(cur));
2886 } else if (cur->mark_copied()) {
2887 // Try to copy the content of the shadow region back to its corresponding
2888 // heap region if the shadow region is filled. Otherwise, the GC thread
2889 // fills the shadow region will copy the data back (see
2890 // MoveAndUpdateShadowClosure::complete_region).
2891 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2892 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2893 cur->set_completed();
2894 }
2895 }
2896 }
2897 }
2898
2899 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2900 SpaceId& src_space_id,
2901 HeapWord*& src_space_top,
2902 HeapWord* end_addr)
2903 {
2904 typedef ParallelCompactData::RegionData RegionData;
2905
2906 ParallelCompactData& sd = PSParallelCompact::summary_data();
2907 const size_t region_size = ParallelCompactData::RegionSize;
2908
2909 size_t src_region_idx = 0;
2910
2911 // Skip empty regions (if any) up to the top of the space.
2912 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2913 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2914 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2915 const RegionData* const top_region_ptr =
2916 sd.addr_to_region_ptr(top_aligned_up);
2917 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2918 ++src_region_ptr;
2919 }
2920
2921 if (src_region_ptr < top_region_ptr) {
2922 // The next source region is in the current space. Update src_region_idx
2923 // and the source address to match src_region_ptr.
2924 src_region_idx = sd.region(src_region_ptr);
2925 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2926 if (src_region_addr > closure.source()) {
2927 closure.set_source(src_region_addr);
2928 }
2929 return src_region_idx;
2930 }
2931
2932 // Switch to a new source space and find the first non-empty region.
2933 unsigned int space_id = src_space_id + 1;
2934 assert(space_id < last_space_id, "not enough spaces");
2935
2936 HeapWord* const destination = closure.destination();
2937
2938 do {
2939 MutableSpace* space = _space_info[space_id].space();
2940 HeapWord* const bottom = space->bottom();
2941 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2942
2943 // Iterate over the spaces that do not compact into themselves.
2944 if (bottom_cp->destination() != bottom) {
2945 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2946 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2947
2948 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2949 if (src_cp->live_obj_size() > 0) {
2950 // Found it.
2951 assert(src_cp->destination() == destination,
2952 "first live obj in the space must match the destination");
2953 assert(src_cp->partial_obj_size() == 0,
2954 "a space cannot begin with a partial obj");
2955
2956 src_space_id = SpaceId(space_id);
2957 src_space_top = space->top();
2958 const size_t src_region_idx = sd.region(src_cp);
2959 closure.set_source(sd.region_to_addr(src_region_idx));
2960 return src_region_idx;
2961 } else {
2962 assert(src_cp->data_size() == 0, "sanity");
2963 }
2964 }
2965 }
2966 } while (++space_id < last_space_id);
2967
2968 assert(false, "no source region was found");
2969 return 0;
2970 }
2971
2972 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2973 {
2974 typedef ParMarkBitMap::IterationStatus IterationStatus;
2975 ParMarkBitMap* const bitmap = mark_bitmap();
2976 ParallelCompactData& sd = summary_data();
2977 RegionData* const region_ptr = sd.region(region_idx);
2978
2979 // Get the source region and related info.
2980 size_t src_region_idx = region_ptr->source_region();
2981 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2982 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2983 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2984
2985 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2986
2987 // Adjust src_region_idx to prepare for decrementing destination counts (the
2988 // destination count is not decremented when a region is copied to itself).
2989 if (src_region_idx == region_idx) {
2990 src_region_idx += 1;
2991 }
2992
2993 if (bitmap->is_unmarked(closure.source())) {
2994 // The first source word is in the middle of an object; copy the remainder
2995 // of the object or as much as will fit. The fact that pointer updates were
2996 // deferred will be noted when the object header is processed.
2997 HeapWord* const old_src_addr = closure.source();
2998 closure.copy_partial_obj();
2999 if (closure.is_full()) {
3000 decrement_destination_counts(cm, src_space_id, src_region_idx,
3001 closure.source());
3002 region_ptr->set_deferred_obj_addr(NULL);
3003 closure.complete_region(cm, dest_addr, region_ptr);
3004 return;
3005 }
3006
3007 HeapWord* const end_addr = sd.region_align_down(closure.source());
3008 if (sd.region_align_down(old_src_addr) != end_addr) {
3009 // The partial object was copied from more than one source region.
3010 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3011
3012 // Move to the next source region, possibly switching spaces as well. All
3013 // args except end_addr may be modified.
3014 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3015 end_addr);
3016 }
3017 }
3018
3019 do {
3020 HeapWord* const cur_addr = closure.source();
3021 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3022 src_space_top);
3023 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3024
3025 if (status == ParMarkBitMap::incomplete) {
3026 // The last obj that starts in the source region does not end in the
3027 // region.
3028 assert(closure.source() < end_addr, "sanity");
3029 HeapWord* const obj_beg = closure.source();
3030 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3031 src_space_top);
3032 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3033 if (obj_end < range_end) {
3034 // The end was found; the entire object will fit.
3035 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3036 assert(status != ParMarkBitMap::would_overflow, "sanity");
3037 } else {
3038 // The end was not found; the object will not fit.
3039 assert(range_end < src_space_top, "obj cannot cross space boundary");
3040 status = ParMarkBitMap::would_overflow;
3041 }
3042 }
3043
3044 if (status == ParMarkBitMap::would_overflow) {
3045 // The last object did not fit. Note that interior oop updates were
3046 // deferred, then copy enough of the object to fill the region.
3047 region_ptr->set_deferred_obj_addr(closure.destination());
3048 status = closure.copy_until_full(); // copies from closure.source()
3049
3050 decrement_destination_counts(cm, src_space_id, src_region_idx,
3051 closure.source());
3052 closure.complete_region(cm, dest_addr, region_ptr);
3053 return;
3054 }
3055
3056 if (status == ParMarkBitMap::full) {
3057 decrement_destination_counts(cm, src_space_id, src_region_idx,
3058 closure.source());
3059 region_ptr->set_deferred_obj_addr(NULL);
3060 closure.complete_region(cm, dest_addr, region_ptr);
3061 return;
3062 }
3063
3064 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3065
3066 // Move to the next source region, possibly switching spaces as well. All
3067 // args except end_addr may be modified.
3068 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3069 end_addr);
3070 } while (true);
3071 }
3072
3073 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
3074 {
3075 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
3076 fill_region(cm, cl, region_idx);
3077 }
3078
3079 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
3080 {
3081 // Get a shadow region first
3082 ParallelCompactData& sd = summary_data();
3083 RegionData* const region_ptr = sd.region(region_idx);
3084 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
3085 // The InvalidShadow return value indicates the corresponding heap region is available,
3086 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
3087 // MoveAndUpdateShadowClosure to fill the acquired shadow region.
3088 if (shadow_region == ParCompactionManager::InvalidShadow) {
3089 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
3090 region_ptr->shadow_to_normal();
3091 return fill_region(cm, cl, region_idx);
3092 } else {
3093 MoveAndUpdateShadowClosure cl(mark_bitmap(), cm, region_idx, shadow_region);
3094 return fill_region(cm, cl, region_idx);
3095 }
3096 }
3097
3098 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
3099 {
3100 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
3101 }
3102
3103 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx)
3104 {
3105 size_t next = cm->next_shadow_region();
3106 ParallelCompactData& sd = summary_data();
3107 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
3108 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
3109
3110 while (next < old_new_top) {
3111 if (sd.region(next)->mark_shadow()) {
3112 region_idx = next;
3113 return true;
3114 }
3115 next = cm->move_next_shadow_region_by(active_gc_threads);
3116 }
3117
3118 return false;
3119 }
3120
3121 // The shadow region is an optimization to address region dependencies in full GC. The basic
3122 // idea is making more regions available by temporally storing their live objects in empty
3123 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
3124 // GC threads need not wait destination regions to be available before processing sources.
3125 //
3126 // A typical workflow would be:
3127 // After draining its own stack and failing to steal from others, a GC worker would pick an
3128 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
3129 // the shadow region by copying live objects from source regions of the unavailable one. Once
3130 // the unavailable region becomes available, the data in the shadow region will be copied back.
3131 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
3132 //
3133 // For more details, please refer to ยง4.2 of the VEE'19 paper:
3134 // Haoyu Li, Mingyu Wu, Binyu Zang, and Haibo Chen. 2019. ScissorGC: scalable and efficient
3135 // compaction for Java full garbage collection. In Proceedings of the 15th ACM SIGPLAN/SIGOPS
3136 // International Conference on Virtual Execution Environments (VEE 2019). ACM, New York, NY, USA,
3137 // 108-121. DOI: https://doi.org/10.1145/3313808.3313820
3138 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
3139 {
3140 const ParallelCompactData& sd = PSParallelCompact::summary_data();
3141
3142 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
3143 SpaceInfo* const space_info = _space_info + id;
3144 MutableSpace* const space = space_info->space();
3145
3146 const size_t beg_region =
3147 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
3148 const size_t end_region =
3149 sd.addr_to_region_idx(sd.region_align_down(space->end()));
3150
3151 for (size_t cur = beg_region; cur < end_region; ++cur) {
3152 ParCompactionManager::push_shadow_region(cur);
3153 }
3154 }
3155
3156 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
3157 for (uint i = 0; i < parallel_gc_threads; i++) {
3158 ParCompactionManager *cm = ParCompactionManager::manager_array(i);
3159 cm->set_next_shadow_region(beg_region + i);
3160 }
3161 }
3162
3163 void PSParallelCompact::fill_blocks(size_t region_idx)
3164 {
3165 // Fill in the block table elements for the specified region. Each block
3166 // table element holds the number of live words in the region that are to the
3167 // left of the first object that starts in the block. Thus only blocks in
3168 // which an object starts need to be filled.
3169 //
3170 // The algorithm scans the section of the bitmap that corresponds to the
3171 // region, keeping a running total of the live words. When an object start is
3172 // found, if it's the first to start in the block that contains it, the
3173 // current total is written to the block table element.
3174 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
3175 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
3176 const size_t RegionSize = ParallelCompactData::RegionSize;
3177
3178 ParallelCompactData& sd = summary_data();
3179 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
3180 if (partial_obj_size >= RegionSize) {
3181 return; // No objects start in this region.
3182 }
3183
3184 // Ensure the first loop iteration decides that the block has changed.
3185 size_t cur_block = sd.block_count();
3186
3187 const ParMarkBitMap* const bitmap = mark_bitmap();
3188
3189 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
3190 assert((size_t)1 << Log2BitsPerBlock ==
3191 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
3192
3193 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
3194 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
3195 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
3196 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
3197 while (beg_bit < range_end) {
3198 const size_t new_block = beg_bit >> Log2BitsPerBlock;
3199 if (new_block != cur_block) {
3200 cur_block = new_block;
3201 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
3202 }
3203
3204 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
3205 if (end_bit < range_end - 1) {
3206 live_bits += end_bit - beg_bit + 1;
3207 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
3208 } else {
3209 return;
3210 }
3211 }
3212 }
3213
3214 jlong PSParallelCompact::millis_since_last_gc() {
3215 // We need a monotonically non-decreasing time in ms but
3216 // os::javaTimeMillis() does not guarantee monotonicity.
3217 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3218 jlong ret_val = now - _time_of_last_gc;
3219 // XXX See note in genCollectedHeap::millis_since_last_gc().
3220 if (ret_val < 0) {
3221 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3222 return 0;
3223 }
3224 return ret_val;
3225 }
3226
3227 void PSParallelCompact::reset_millis_since_last_gc() {
3228 // We need a monotonically non-decreasing time in ms but
3229 // os::javaTimeMillis() does not guarantee monotonicity.
3230 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3231 }
3232
3233 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3234 {
3235 if (source() != copy_destination()) {
3236 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3237 Copy::aligned_conjoint_words(source(), copy_destination(), words_remaining());
3238 }
3239 update_state(words_remaining());
3240 assert(is_full(), "sanity");
3241 return ParMarkBitMap::full;
3242 }
3243
3244 void MoveAndUpdateClosure::copy_partial_obj()
3245 {
3246 size_t words = words_remaining();
3247
3248 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3249 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3250 if (end_addr < range_end) {
3251 words = bitmap()->obj_size(source(), end_addr);
3252 }
3253
3254 // This test is necessary; if omitted, the pointer updates to a partial object
3255 // that crosses the dense prefix boundary could be overwritten.
3256 if (source() != copy_destination()) {
3257 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3258 Copy::aligned_conjoint_words(source(), copy_destination(), words);
3259 }
3260 update_state(words);
3261 }
3262
3263 void MoveAndUpdateClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
3264 PSParallelCompact::RegionData *region_ptr) {
3265 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
3266 region_ptr->set_completed();
3267 }
3268
3269 ParMarkBitMapClosure::IterationStatus
3270 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3271 assert(destination() != NULL, "sanity");
3272 assert(bitmap()->obj_size(addr) == words, "bad size");
3273
3274 _source = addr;
3275 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3276 destination(), "wrong destination");
3277
3278 if (words > words_remaining()) {
3279 return ParMarkBitMap::would_overflow;
3280 }
3281
3282 // The start_array must be updated even if the object is not moving.
3283 if (_start_array != NULL) {
3284 _start_array->allocate_block(destination());
3285 }
3286
3287 if (copy_destination() != source()) {
3288 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3289 Copy::aligned_conjoint_words(source(), copy_destination(), words);
3290 }
3291
3292 oop moved_oop = (oop) copy_destination();
3293 compaction_manager()->update_contents(moved_oop);
3294 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3295
3296 update_state(words);
3297 assert(copy_destination() == cast_from_oop<HeapWord*>(moved_oop) + moved_oop->size(), "sanity");
3298 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3299 }
3300
3301 void MoveAndUpdateShadowClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
3302 PSParallelCompact::RegionData *region_ptr) {
3303 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
3304 // Record the shadow region index
3305 region_ptr->set_shadow_region(_shadow);
3306 // Mark the shadow region as filled to indicate the data is ready to be
3307 // copied back
3308 region_ptr->mark_filled();
3309 // Try to copy the content of the shadow region back to its corresponding
3310 // heap region if available; the GC thread that decreases the destination
3311 // count to zero will do the copying otherwise (see
3312 // PSParallelCompact::decrement_destination_counts).
3313 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
3314 region_ptr->set_completed();
3315 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
3316 ParCompactionManager::push_shadow_region_mt_safe(_shadow);
3317 }
3318 }
3319
3320 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3321 ParCompactionManager* cm,
3322 PSParallelCompact::SpaceId space_id) :
3323 ParMarkBitMapClosure(mbm, cm),
3324 _space_id(space_id),
3325 _start_array(PSParallelCompact::start_array(space_id))
3326 {
3327 }
3328
3329 // Updates the references in the object to their new values.
3330 ParMarkBitMapClosure::IterationStatus
3331 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3332 do_addr(addr);
3333 return ParMarkBitMap::incomplete;
3334 }
3335
3336 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3337 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3338 _start_array(PSParallelCompact::start_array(space_id))
3339 {
3340 assert(space_id == PSParallelCompact::old_space_id,
3341 "cannot use FillClosure in the young gen");
3342 }
3343
3344 ParMarkBitMapClosure::IterationStatus
3345 FillClosure::do_addr(HeapWord* addr, size_t size) {
3346 CollectedHeap::fill_with_objects(addr, size);
3347 HeapWord* const end = addr + size;
3348 do {
3349 _start_array->allocate_block(addr);
3350 addr += oop(addr)->size();
3351 } while (addr < end);
3352 return ParMarkBitMap::incomplete;
3353 }