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