1 /*
2 * Copyright (c) 2005, 2022, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/javaClasses.inline.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "code/codeCache.hpp"
32 #include "compiler/oopMap.hpp"
33 #include "gc/parallel/parallelArguments.hpp"
34 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
35 #include "gc/parallel/parMarkBitMap.inline.hpp"
36 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
37 #include "gc/parallel/psCompactionManager.inline.hpp"
38 #include "gc/parallel/psOldGen.hpp"
39 #include "gc/parallel/psParallelCompact.inline.hpp"
40 #include "gc/parallel/psPromotionManager.inline.hpp"
41 #include "gc/parallel/psRootType.hpp"
42 #include "gc/parallel/psScavenge.hpp"
43 #include "gc/parallel/psStringDedup.hpp"
44 #include "gc/parallel/psYoungGen.hpp"
45 #include "gc/shared/gcCause.hpp"
46 #include "gc/shared/gcHeapSummary.hpp"
47 #include "gc/shared/gcId.hpp"
48 #include "gc/shared/gcLocker.hpp"
49 #include "gc/shared/gcTimer.hpp"
50 #include "gc/shared/gcTrace.hpp"
51 #include "gc/shared/gcTraceTime.inline.hpp"
52 #include "gc/shared/isGCActiveMark.hpp"
53 #include "gc/shared/oopStorage.inline.hpp"
54 #include "gc/shared/oopStorageSet.inline.hpp"
55 #include "gc/shared/oopStorageSetParState.inline.hpp"
56 #include "gc/shared/referencePolicy.hpp"
57 #include "gc/shared/referenceProcessor.hpp"
58 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
59 #include "gc/shared/spaceDecorator.inline.hpp"
60 #include "gc/shared/taskTerminator.hpp"
61 #include "gc/shared/weakProcessor.inline.hpp"
62 #include "gc/shared/workerPolicy.hpp"
63 #include "gc/shared/workerThread.hpp"
64 #include "gc/shared/workerUtils.hpp"
65 #include "logging/log.hpp"
66 #include "memory/iterator.inline.hpp"
67 #include "memory/metaspaceUtils.hpp"
68 #include "memory/resourceArea.hpp"
69 #include "memory/universe.hpp"
70 #include "oops/access.inline.hpp"
71 #include "oops/flatArrayKlass.inline.hpp"
72 #include "oops/instanceClassLoaderKlass.inline.hpp"
73 #include "oops/instanceKlass.inline.hpp"
74 #include "oops/instanceMirrorKlass.inline.hpp"
75 #include "oops/methodData.hpp"
76 #include "oops/objArrayKlass.inline.hpp"
77 #include "oops/oop.inline.hpp"
78 #include "runtime/atomic.hpp"
79 #include "runtime/handles.inline.hpp"
80 #include "runtime/java.hpp"
81 #include "runtime/safepoint.hpp"
82 #include "runtime/threads.hpp"
83 #include "runtime/vmThread.hpp"
84 #include "services/memTracker.hpp"
85 #include "services/memoryService.hpp"
86 #include "utilities/align.hpp"
87 #include "utilities/debug.hpp"
88 #include "utilities/events.hpp"
89 #include "utilities/formatBuffer.hpp"
90 #include "utilities/macros.hpp"
91 #include "utilities/stack.inline.hpp"
92 #if INCLUDE_JVMCI
93 #include "jvmci/jvmci.hpp"
94 #endif
95
96 #include <math.h>
97
98 // All sizes are in HeapWords.
99 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
100 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
101 const size_t ParallelCompactData::RegionSizeBytes =
102 RegionSize << LogHeapWordSize;
103 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
104 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
105 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
106
107 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
108 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
109 const size_t ParallelCompactData::BlockSizeBytes =
110 BlockSize << LogHeapWordSize;
111 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
112 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
113 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
114
115 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
116 const size_t ParallelCompactData::Log2BlocksPerRegion =
117 Log2RegionSize - Log2BlockSize;
118
119 const ParallelCompactData::RegionData::region_sz_t
120 ParallelCompactData::RegionData::dc_shift = 27;
121
122 const ParallelCompactData::RegionData::region_sz_t
123 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
124
125 const ParallelCompactData::RegionData::region_sz_t
126 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
127
128 const ParallelCompactData::RegionData::region_sz_t
129 ParallelCompactData::RegionData::los_mask = ~dc_mask;
130
131 const ParallelCompactData::RegionData::region_sz_t
132 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
133
134 const ParallelCompactData::RegionData::region_sz_t
135 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
136
137 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
138
139 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
140 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
141
142 double PSParallelCompact::_dwl_mean;
143 double PSParallelCompact::_dwl_std_dev;
144 double PSParallelCompact::_dwl_first_term;
145 double PSParallelCompact::_dwl_adjustment;
146 #ifdef ASSERT
147 bool PSParallelCompact::_dwl_initialized = false;
148 #endif // #ifdef ASSERT
149
150 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
151 HeapWord* destination)
152 {
153 assert(src_region_idx != 0, "invalid src_region_idx");
154 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
155 assert(destination != NULL, "invalid destination argument");
156
157 _src_region_idx = src_region_idx;
158 _partial_obj_size = partial_obj_size;
159 _destination = destination;
160
161 // These fields may not be updated below, so make sure they're clear.
162 assert(_dest_region_addr == NULL, "should have been cleared");
163 assert(_first_src_addr == NULL, "should have been cleared");
164
165 // Determine the number of destination regions for the partial object.
166 HeapWord* const last_word = destination + partial_obj_size - 1;
167 const ParallelCompactData& sd = PSParallelCompact::summary_data();
168 HeapWord* const beg_region_addr = sd.region_align_down(destination);
169 HeapWord* const end_region_addr = sd.region_align_down(last_word);
170
171 if (beg_region_addr == end_region_addr) {
172 // One destination region.
173 _destination_count = 1;
174 if (end_region_addr == destination) {
175 // The destination falls on a region boundary, thus the first word of the
176 // partial object will be the first word copied to the destination region.
177 _dest_region_addr = end_region_addr;
178 _first_src_addr = sd.region_to_addr(src_region_idx);
179 }
180 } else {
181 // Two destination regions. When copied, the partial object will cross a
182 // destination region boundary, so a word somewhere within the partial
183 // object will be the first word copied to the second destination region.
184 _destination_count = 2;
185 _dest_region_addr = end_region_addr;
186 const size_t ofs = pointer_delta(end_region_addr, destination);
187 assert(ofs < _partial_obj_size, "sanity");
188 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
189 }
190 }
191
192 void SplitInfo::clear()
193 {
194 _src_region_idx = 0;
195 _partial_obj_size = 0;
196 _destination = NULL;
197 _destination_count = 0;
198 _dest_region_addr = NULL;
199 _first_src_addr = NULL;
200 assert(!is_valid(), "sanity");
201 }
202
203 #ifdef ASSERT
204 void SplitInfo::verify_clear()
205 {
206 assert(_src_region_idx == 0, "not clear");
207 assert(_partial_obj_size == 0, "not clear");
208 assert(_destination == NULL, "not clear");
209 assert(_destination_count == 0, "not clear");
210 assert(_dest_region_addr == NULL, "not clear");
211 assert(_first_src_addr == NULL, "not clear");
212 }
213 #endif // #ifdef ASSERT
214
215
216 void PSParallelCompact::print_on_error(outputStream* st) {
217 _mark_bitmap.print_on_error(st);
218 }
219
220 #ifndef PRODUCT
221 const char* PSParallelCompact::space_names[] = {
222 "old ", "eden", "from", "to "
223 };
224
225 void PSParallelCompact::print_region_ranges() {
226 if (!log_develop_is_enabled(Trace, gc, compaction)) {
227 return;
228 }
229 Log(gc, compaction) log;
230 ResourceMark rm;
231 LogStream ls(log.trace());
232 Universe::print_on(&ls);
233 log.trace("space bottom top end new_top");
234 log.trace("------ ---------- ---------- ---------- ----------");
235
236 for (unsigned int id = 0; id < last_space_id; ++id) {
237 const MutableSpace* space = _space_info[id].space();
238 log.trace("%u %s "
239 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
240 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
241 id, space_names[id],
242 summary_data().addr_to_region_idx(space->bottom()),
243 summary_data().addr_to_region_idx(space->top()),
244 summary_data().addr_to_region_idx(space->end()),
245 summary_data().addr_to_region_idx(_space_info[id].new_top()));
246 }
247 }
248
249 void
250 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
251 {
252 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
253 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
254
255 ParallelCompactData& sd = PSParallelCompact::summary_data();
256 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
257 log_develop_trace(gc, compaction)(
258 REGION_IDX_FORMAT " " PTR_FORMAT " "
259 REGION_IDX_FORMAT " " PTR_FORMAT " "
260 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
261 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
262 i, p2i(c->data_location()), dci, p2i(c->destination()),
263 c->partial_obj_size(), c->live_obj_size(),
264 c->data_size(), c->source_region(), c->destination_count());
265
266 #undef REGION_IDX_FORMAT
267 #undef REGION_DATA_FORMAT
268 }
269
270 void
271 print_generic_summary_data(ParallelCompactData& summary_data,
272 HeapWord* const beg_addr,
273 HeapWord* const end_addr)
274 {
275 size_t total_words = 0;
276 size_t i = summary_data.addr_to_region_idx(beg_addr);
277 const size_t last = summary_data.addr_to_region_idx(end_addr);
278 HeapWord* pdest = 0;
279
280 while (i < last) {
281 ParallelCompactData::RegionData* c = summary_data.region(i);
282 if (c->data_size() != 0 || c->destination() != pdest) {
283 print_generic_summary_region(i, c);
284 total_words += c->data_size();
285 pdest = c->destination();
286 }
287 ++i;
288 }
289
290 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
291 }
292
293 void
294 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
295 HeapWord* const beg_addr,
296 HeapWord* const end_addr) {
297 ::print_generic_summary_data(summary_data,beg_addr, end_addr);
298 }
299
300 void
301 print_generic_summary_data(ParallelCompactData& summary_data,
302 SpaceInfo* space_info)
303 {
304 if (!log_develop_is_enabled(Trace, gc, compaction)) {
305 return;
306 }
307
308 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
309 const MutableSpace* space = space_info[id].space();
310 print_generic_summary_data(summary_data, space->bottom(),
311 MAX2(space->top(), space_info[id].new_top()));
312 }
313 }
314
315 void
316 print_initial_summary_data(ParallelCompactData& summary_data,
317 const MutableSpace* space) {
318 if (space->top() == space->bottom()) {
319 return;
320 }
321
322 const size_t region_size = ParallelCompactData::RegionSize;
323 typedef ParallelCompactData::RegionData RegionData;
324 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
325 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
326 const RegionData* c = summary_data.region(end_region - 1);
327 HeapWord* end_addr = c->destination() + c->data_size();
328 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
329
330 // Print (and count) the full regions at the beginning of the space.
331 size_t full_region_count = 0;
332 size_t i = summary_data.addr_to_region_idx(space->bottom());
333 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
334 ParallelCompactData::RegionData* c = summary_data.region(i);
335 log_develop_trace(gc, compaction)(
336 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
337 i, p2i(c->destination()),
338 c->partial_obj_size(), c->live_obj_size(),
339 c->data_size(), c->source_region(), c->destination_count());
340 ++full_region_count;
341 ++i;
342 }
343
344 size_t live_to_right = live_in_space - full_region_count * region_size;
345
346 double max_reclaimed_ratio = 0.0;
347 size_t max_reclaimed_ratio_region = 0;
348 size_t max_dead_to_right = 0;
349 size_t max_live_to_right = 0;
350
351 // Print the 'reclaimed ratio' for regions while there is something live in
352 // the region or to the right of it. The remaining regions are empty (and
353 // uninteresting), and computing the ratio will result in division by 0.
354 while (i < end_region && live_to_right > 0) {
355 c = summary_data.region(i);
356 HeapWord* const region_addr = summary_data.region_to_addr(i);
357 const size_t used_to_right = pointer_delta(space->top(), region_addr);
358 const size_t dead_to_right = used_to_right - live_to_right;
359 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
360
361 if (reclaimed_ratio > max_reclaimed_ratio) {
362 max_reclaimed_ratio = reclaimed_ratio;
363 max_reclaimed_ratio_region = i;
364 max_dead_to_right = dead_to_right;
365 max_live_to_right = live_to_right;
366 }
367
368 ParallelCompactData::RegionData* c = summary_data.region(i);
369 log_develop_trace(gc, compaction)(
370 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
371 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
372 i, p2i(c->destination()),
373 c->partial_obj_size(), c->live_obj_size(),
374 c->data_size(), c->source_region(), c->destination_count(),
375 reclaimed_ratio, dead_to_right, live_to_right);
376
377
378 live_to_right -= c->data_size();
379 ++i;
380 }
381
382 // Any remaining regions are empty. Print one more if there is one.
383 if (i < end_region) {
384 ParallelCompactData::RegionData* c = summary_data.region(i);
385 log_develop_trace(gc, compaction)(
386 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
387 i, p2i(c->destination()),
388 c->partial_obj_size(), c->live_obj_size(),
389 c->data_size(), c->source_region(), c->destination_count());
390 }
391
392 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
393 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
394 }
395
396 void
397 print_initial_summary_data(ParallelCompactData& summary_data,
398 SpaceInfo* space_info) {
399 if (!log_develop_is_enabled(Trace, gc, compaction)) {
400 return;
401 }
402
403 unsigned int id = PSParallelCompact::old_space_id;
404 const MutableSpace* space;
405 do {
406 space = space_info[id].space();
407 print_initial_summary_data(summary_data, space);
408 } while (++id < PSParallelCompact::eden_space_id);
409
410 do {
411 space = space_info[id].space();
412 print_generic_summary_data(summary_data, space->bottom(), space->top());
413 } while (++id < PSParallelCompact::last_space_id);
414 }
415 #endif // #ifndef PRODUCT
416
417 ParallelCompactData::ParallelCompactData() :
418 _region_start(NULL),
419 DEBUG_ONLY(_region_end(NULL) COMMA)
420 _region_vspace(NULL),
421 _reserved_byte_size(0),
422 _region_data(NULL),
423 _region_count(0),
424 _block_vspace(NULL),
425 _block_data(NULL),
426 _block_count(0) {}
427
428 bool ParallelCompactData::initialize(MemRegion covered_region)
429 {
430 _region_start = covered_region.start();
431 const size_t region_size = covered_region.word_size();
432 DEBUG_ONLY(_region_end = _region_start + region_size;)
433
434 assert(region_align_down(_region_start) == _region_start,
435 "region start not aligned");
436
437 bool result = initialize_region_data(region_size) && initialize_block_data();
438 return result;
439 }
440
441 PSVirtualSpace*
442 ParallelCompactData::create_vspace(size_t count, size_t element_size)
443 {
444 const size_t raw_bytes = count * element_size;
445 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
446 const size_t granularity = os::vm_allocation_granularity();
447 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
448
449 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
450 MAX2(page_sz, granularity);
451 ReservedSpace rs(_reserved_byte_size, rs_align, page_sz);
452 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
453 rs.size());
454
455 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
456
457 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
458 if (vspace != 0) {
459 if (vspace->expand_by(_reserved_byte_size)) {
460 return vspace;
461 }
462 delete vspace;
463 // Release memory reserved in the space.
464 rs.release();
465 }
466
467 return 0;
468 }
469
470 bool ParallelCompactData::initialize_region_data(size_t region_size)
471 {
472 assert((region_size & RegionSizeOffsetMask) == 0,
473 "region size not a multiple of RegionSize");
474
475 const size_t count = region_size >> 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 // end_region is inclusive
536 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
537
538 if (beg_region == end_region) {
539 // All in one region.
540 _region_data[beg_region].add_live_obj(len);
541 return;
542 }
543
544 // First region.
545 const size_t beg_ofs = region_offset(addr);
546 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
547
548 // Middle regions--completely spanned by this object.
549 for (size_t region = beg_region + 1; region < end_region; ++region) {
550 _region_data[region].set_partial_obj_size(RegionSize);
551 _region_data[region].set_partial_obj_addr(addr);
552 }
553
554 // Last region.
555 const size_t end_ofs = region_offset(addr + len - 1);
556 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
557 _region_data[end_region].set_partial_obj_addr(addr);
558 }
559
560 void
561 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
562 {
563 assert(is_region_aligned(beg), "not RegionSize aligned");
564 assert(is_region_aligned(end), "not RegionSize aligned");
565
566 size_t cur_region = addr_to_region_idx(beg);
567 const size_t end_region = addr_to_region_idx(end);
568 HeapWord* addr = beg;
569 while (cur_region < end_region) {
570 _region_data[cur_region].set_destination(addr);
571 _region_data[cur_region].set_destination_count(0);
572 _region_data[cur_region].set_source_region(cur_region);
573 _region_data[cur_region].set_data_location(addr);
574
575 // Update live_obj_size so the region appears completely full.
576 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
577 _region_data[cur_region].set_live_obj_size(live_size);
578
579 ++cur_region;
580 addr += RegionSize;
581 }
582 }
583
584 // Find the point at which a space can be split and, if necessary, record the
585 // split point.
586 //
587 // If the current src region (which overflowed the destination space) doesn't
588 // have a partial object, the split point is at the beginning of the current src
589 // region (an "easy" split, no extra bookkeeping required).
590 //
591 // If the current src region has a partial object, the split point is in the
592 // region where that partial object starts (call it the split_region). If
593 // split_region has a partial object, then the split point is just after that
594 // partial object (a "hard" split where we have to record the split data and
595 // zero the partial_obj_size field). With a "hard" split, we know that the
596 // partial_obj ends within split_region because the partial object that caused
597 // the overflow starts in split_region. If split_region doesn't have a partial
598 // obj, then the split is at the beginning of split_region (another "easy"
599 // split).
600 HeapWord*
601 ParallelCompactData::summarize_split_space(size_t src_region,
602 SplitInfo& split_info,
603 HeapWord* destination,
604 HeapWord* target_end,
605 HeapWord** target_next)
606 {
607 assert(destination <= target_end, "sanity");
608 assert(destination + _region_data[src_region].data_size() > target_end,
609 "region should not fit into target space");
610 assert(is_region_aligned(target_end), "sanity");
611
612 size_t split_region = src_region;
613 HeapWord* split_destination = destination;
614 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
615
616 if (destination + partial_obj_size > target_end) {
617 // The split point is just after the partial object (if any) in the
618 // src_region that contains the start of the object that overflowed the
619 // destination space.
620 //
621 // Find the start of the "overflow" object and set split_region to the
622 // region containing it.
623 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
624 split_region = addr_to_region_idx(overflow_obj);
625
626 // Clear the source_region field of all destination regions whose first word
627 // came from data after the split point (a non-null source_region field
628 // implies a region must be filled).
629 //
630 // An alternative to the simple loop below: clear during post_compact(),
631 // which uses memcpy instead of individual stores, and is easy to
632 // parallelize. (The downside is that it clears the entire RegionData
633 // object as opposed to just one field.)
634 //
635 // post_compact() would have to clear the summary data up to the highest
636 // address that was written during the summary phase, which would be
637 //
638 // max(top, max(new_top, clear_top))
639 //
640 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
641 // to target_end.
642 const RegionData* const sr = region(split_region);
643 const size_t beg_idx =
644 addr_to_region_idx(region_align_up(sr->destination() +
645 sr->partial_obj_size()));
646 const size_t end_idx = addr_to_region_idx(target_end);
647
648 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
649 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
650 _region_data[idx].set_source_region(0);
651 }
652
653 // Set split_destination and partial_obj_size to reflect the split region.
654 split_destination = sr->destination();
655 partial_obj_size = sr->partial_obj_size();
656 }
657
658 // The split is recorded only if a partial object extends onto the region.
659 if (partial_obj_size != 0) {
660 _region_data[split_region].set_partial_obj_size(0);
661 split_info.record(split_region, partial_obj_size, split_destination);
662 }
663
664 // Setup the continuation addresses.
665 *target_next = split_destination + partial_obj_size;
666 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
667
668 if (log_develop_is_enabled(Trace, gc, compaction)) {
669 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
670 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
671 split_type, p2i(source_next), split_region, partial_obj_size);
672 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
673 split_type, p2i(split_destination),
674 addr_to_region_idx(split_destination),
675 p2i(*target_next));
676
677 if (partial_obj_size != 0) {
678 HeapWord* const po_beg = split_info.destination();
679 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
680 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
681 split_type,
682 p2i(po_beg), addr_to_region_idx(po_beg),
683 p2i(po_end), addr_to_region_idx(po_end));
684 }
685 }
686
687 return source_next;
688 }
689
690 bool ParallelCompactData::summarize(SplitInfo& split_info,
691 HeapWord* source_beg, HeapWord* source_end,
692 HeapWord** source_next,
693 HeapWord* target_beg, HeapWord* target_end,
694 HeapWord** target_next)
695 {
696 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
697 log_develop_trace(gc, compaction)(
698 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
699 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
700 p2i(source_beg), p2i(source_end), p2i(source_next_val),
701 p2i(target_beg), p2i(target_end), p2i(*target_next));
702
703 size_t cur_region = addr_to_region_idx(source_beg);
704 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
705
706 HeapWord *dest_addr = target_beg;
707 while (cur_region < end_region) {
708 // The destination must be set even if the region has no data.
709 _region_data[cur_region].set_destination(dest_addr);
710
711 size_t words = _region_data[cur_region].data_size();
712 if (words > 0) {
713 // If cur_region does not fit entirely into the target space, find a point
714 // at which the source space can be 'split' so that part is copied to the
715 // target space and the rest is copied elsewhere.
716 if (dest_addr + words > target_end) {
717 assert(source_next != NULL, "source_next is NULL when splitting");
718 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
719 target_end, target_next);
720 return false;
721 }
722
723 // Compute the destination_count for cur_region, and if necessary, update
724 // source_region for a destination region. The source_region field is
725 // updated if cur_region is the first (left-most) region to be copied to a
726 // destination region.
727 //
728 // The destination_count calculation is a bit subtle. A region that has
729 // data that compacts into itself does not count itself as a destination.
730 // This maintains the invariant that a zero count means the region is
731 // available and can be claimed and then filled.
732 uint destination_count = 0;
733 if (split_info.is_split(cur_region)) {
734 // The current region has been split: the partial object will be copied
735 // to one destination space and the remaining data will be copied to
736 // another destination space. Adjust the initial destination_count and,
737 // if necessary, set the source_region field if the partial object will
738 // cross a destination region boundary.
739 destination_count = split_info.destination_count();
740 if (destination_count == 2) {
741 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
742 _region_data[dest_idx].set_source_region(cur_region);
743 }
744 }
745
746 HeapWord* const last_addr = dest_addr + words - 1;
747 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
748 const size_t dest_region_2 = addr_to_region_idx(last_addr);
749
750 // Initially assume that the destination regions will be the same and
751 // adjust the value below if necessary. Under this assumption, if
752 // cur_region == dest_region_2, then cur_region will be compacted
753 // completely into itself.
754 destination_count += cur_region == dest_region_2 ? 0 : 1;
755 if (dest_region_1 != dest_region_2) {
756 // Destination regions differ; adjust destination_count.
757 destination_count += 1;
758 // Data from cur_region will be copied to the start of dest_region_2.
759 _region_data[dest_region_2].set_source_region(cur_region);
760 } else if (is_region_aligned(dest_addr)) {
761 // Data from cur_region will be copied to the start of the destination
762 // region.
763 _region_data[dest_region_1].set_source_region(cur_region);
764 }
765
766 _region_data[cur_region].set_destination_count(destination_count);
767 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
768 dest_addr += words;
769 }
770
771 ++cur_region;
772 }
773
774 *target_next = dest_addr;
775 return true;
776 }
777
778 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) const {
779 assert(addr != NULL, "Should detect NULL oop earlier");
780 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
781 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
782
783 // Region covering the object.
784 RegionData* const region_ptr = addr_to_region_ptr(addr);
785 HeapWord* result = region_ptr->destination();
786
787 // If the entire Region is live, the new location is region->destination + the
788 // offset of the object within in the Region.
789
790 // Run some performance tests to determine if this special case pays off. It
791 // is worth it for pointers into the dense prefix. If the optimization to
792 // avoid pointer updates in regions that only point to the dense prefix is
793 // ever implemented, this should be revisited.
794 if (region_ptr->data_size() == RegionSize) {
795 result += region_offset(addr);
796 return result;
797 }
798
799 // Otherwise, the new location is region->destination + block offset + the
800 // number of live words in the Block that are (a) to the left of addr and (b)
801 // due to objects that start in the Block.
802
803 // Fill in the block table if necessary. This is unsynchronized, so multiple
804 // threads may fill the block table for a region (harmless, since it is
805 // idempotent).
806 if (!region_ptr->blocks_filled()) {
807 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
808 region_ptr->set_blocks_filled();
809 }
810
811 HeapWord* const search_start = block_align_down(addr);
812 const size_t block_offset = addr_to_block_ptr(addr)->offset();
813
814 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
815 const size_t live = bitmap->live_words_in_range(cm, search_start, cast_to_oop(addr));
816 result += block_offset + live;
817 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
818 return result;
819 }
820
821 #ifdef ASSERT
822 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
823 {
824 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
825 const size_t* const end = (const size_t*)vspace->committed_high_addr();
826 for (const size_t* p = beg; p < end; ++p) {
827 assert(*p == 0, "not zero");
828 }
829 }
830
831 void ParallelCompactData::verify_clear()
832 {
833 verify_clear(_region_vspace);
834 verify_clear(_block_vspace);
835 }
836 #endif // #ifdef ASSERT
837
838 STWGCTimer PSParallelCompact::_gc_timer;
839 ParallelOldTracer PSParallelCompact::_gc_tracer;
840 elapsedTimer PSParallelCompact::_accumulated_time;
841 unsigned int PSParallelCompact::_total_invocations = 0;
842 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
843 CollectorCounters* PSParallelCompact::_counters = NULL;
844 ParMarkBitMap PSParallelCompact::_mark_bitmap;
845 ParallelCompactData PSParallelCompact::_summary_data;
846
847 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
848
849 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
850
851 void PSParallelCompact::post_initialize() {
852 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
853 _span_based_discoverer.set_span(heap->reserved_region());
854 _ref_processor =
855 new ReferenceProcessor(&_span_based_discoverer,
856 ParallelGCThreads, // mt processing degree
857 ParallelGCThreads, // mt discovery degree
858 false, // concurrent_discovery
859 &_is_alive_closure); // non-header is alive closure
860
861 _counters = new CollectorCounters("Parallel full collection pauses", 1);
862
863 // Initialize static fields in ParCompactionManager.
864 ParCompactionManager::initialize(mark_bitmap());
865 }
866
867 bool PSParallelCompact::initialize() {
868 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
869 MemRegion mr = heap->reserved_region();
870
871 // Was the old gen get allocated successfully?
872 if (!heap->old_gen()->is_allocated()) {
873 return false;
874 }
875
876 initialize_space_info();
877 initialize_dead_wood_limiter();
878
879 if (!_mark_bitmap.initialize(mr)) {
880 vm_shutdown_during_initialization(
881 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
882 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
883 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
884 return false;
885 }
886
887 if (!_summary_data.initialize(mr)) {
888 vm_shutdown_during_initialization(
889 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
890 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
891 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
892 return false;
893 }
894
895 return true;
896 }
897
898 void PSParallelCompact::initialize_space_info()
899 {
900 memset(&_space_info, 0, sizeof(_space_info));
901
902 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
903 PSYoungGen* young_gen = heap->young_gen();
904
905 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
906 _space_info[eden_space_id].set_space(young_gen->eden_space());
907 _space_info[from_space_id].set_space(young_gen->from_space());
908 _space_info[to_space_id].set_space(young_gen->to_space());
909
910 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
911 }
912
913 void PSParallelCompact::initialize_dead_wood_limiter()
914 {
915 const size_t max = 100;
916 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
917 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
918 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
919 DEBUG_ONLY(_dwl_initialized = true;)
920 _dwl_adjustment = normal_distribution(1.0);
921 }
922
923 void
924 PSParallelCompact::clear_data_covering_space(SpaceId id)
925 {
926 // At this point, top is the value before GC, new_top() is the value that will
927 // be set at the end of GC. The marking bitmap is cleared to top; nothing
928 // should be marked above top. The summary data is cleared to the larger of
929 // top & new_top.
930 MutableSpace* const space = _space_info[id].space();
931 HeapWord* const bot = space->bottom();
932 HeapWord* const top = space->top();
933 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
934
935 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
936 const idx_t end_bit = _mark_bitmap.align_range_end(_mark_bitmap.addr_to_bit(top));
937 _mark_bitmap.clear_range(beg_bit, end_bit);
938
939 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
940 const size_t end_region =
941 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
942 _summary_data.clear_range(beg_region, end_region);
943
944 // Clear the data used to 'split' regions.
945 SplitInfo& split_info = _space_info[id].split_info();
946 if (split_info.is_valid()) {
947 split_info.clear();
948 }
949 DEBUG_ONLY(split_info.verify_clear();)
950 }
951
952 void PSParallelCompact::pre_compact()
953 {
954 // Update the from & to space pointers in space_info, since they are swapped
955 // at each young gen gc. Do the update unconditionally (even though a
956 // promotion failure does not swap spaces) because an unknown number of young
957 // collections will have swapped the spaces an unknown number of times.
958 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
959 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
960 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
961 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
962
963 // Increment the invocation count
964 heap->increment_total_collections(true);
965
966 CodeCache::on_gc_marking_cycle_start();
967 CodeCache::arm_all_nmethods();
968
969 // We need to track unique mark sweep invocations as well.
970 _total_invocations++;
971
972 heap->print_heap_before_gc();
973 heap->trace_heap_before_gc(&_gc_tracer);
974
975 // Fill in TLABs
976 heap->ensure_parsability(true); // retire TLABs
977
978 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
979 Universe::verify("Before GC");
980 }
981
982 // Verify object start arrays
983 if (VerifyObjectStartArray &&
984 VerifyBeforeGC) {
985 heap->old_gen()->verify_object_start_array();
986 }
987
988 DEBUG_ONLY(mark_bitmap()->verify_clear();)
989 DEBUG_ONLY(summary_data().verify_clear();)
990
991 ParCompactionManager::reset_all_bitmap_query_caches();
992 }
993
994 void PSParallelCompact::post_compact()
995 {
996 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
997 ParCompactionManager::remove_all_shadow_regions();
998
999 CodeCache::on_gc_marking_cycle_finish();
1000 CodeCache::arm_all_nmethods();
1001
1002 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1003 // Clear the marking bitmap, summary data and split info.
1004 clear_data_covering_space(SpaceId(id));
1005 // Update top(). Must be done after clearing the bitmap and summary data.
1006 _space_info[id].publish_new_top();
1007 }
1008
1009 ParCompactionManager::flush_all_string_dedup_requests();
1010
1011 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1012 MutableSpace* const from_space = _space_info[from_space_id].space();
1013 MutableSpace* const to_space = _space_info[to_space_id].space();
1014
1015 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1016 bool eden_empty = eden_space->is_empty();
1017
1018 // Update heap occupancy information which is used as input to the soft ref
1019 // clearing policy at the next gc.
1020 Universe::heap()->update_capacity_and_used_at_gc();
1021
1022 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1023 to_space->is_empty();
1024
1025 PSCardTable* ct = heap->card_table();
1026 MemRegion old_mr = heap->old_gen()->reserved();
1027 if (young_gen_empty) {
1028 ct->clear(old_mr);
1029 } else {
1030 ct->invalidate(old_mr);
1031 }
1032
1033 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1034 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1035 DEBUG_ONLY(MetaspaceUtils::verify();)
1036
1037 heap->prune_scavengable_nmethods();
1038
1039 #if COMPILER2_OR_JVMCI
1040 DerivedPointerTable::update_pointers();
1041 #endif
1042
1043 if (ZapUnusedHeapArea) {
1044 heap->gen_mangle_unused_area();
1045 }
1046
1047 // Signal that we have completed a visit to all live objects.
1048 Universe::heap()->record_whole_heap_examined_timestamp();
1049 }
1050
1051 HeapWord*
1052 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1053 bool maximum_compaction)
1054 {
1055 const size_t region_size = ParallelCompactData::RegionSize;
1056 const ParallelCompactData& sd = summary_data();
1057
1058 const MutableSpace* const space = _space_info[id].space();
1059 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1060 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1061 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1062
1063 // Skip full regions at the beginning of the space--they are necessarily part
1064 // of the dense prefix.
1065 size_t full_count = 0;
1066 const RegionData* cp;
1067 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1068 ++full_count;
1069 }
1070
1071 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1072 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1073 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1074 if (maximum_compaction || cp == end_cp || interval_ended) {
1075 _maximum_compaction_gc_num = total_invocations();
1076 return sd.region_to_addr(cp);
1077 }
1078
1079 HeapWord* const new_top = _space_info[id].new_top();
1080 const size_t space_live = pointer_delta(new_top, space->bottom());
1081 const size_t space_used = space->used_in_words();
1082 const size_t space_capacity = space->capacity_in_words();
1083
1084 const double cur_density = double(space_live) / space_capacity;
1085 const double deadwood_density =
1086 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1087 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1088
1089 log_develop_debug(gc, compaction)(
1090 "cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1091 cur_density, deadwood_density, deadwood_goal);
1092 log_develop_debug(gc, compaction)(
1093 "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " "
1094 "space_cap=" SIZE_FORMAT,
1095 space_live, space_used,
1096 space_capacity);
1097
1098 // XXX - Use binary search?
1099 HeapWord* dense_prefix = sd.region_to_addr(cp);
1100 const RegionData* full_cp = cp;
1101 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1102 while (cp < end_cp) {
1103 HeapWord* region_destination = cp->destination();
1104 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1105
1106 log_develop_trace(gc, compaction)(
1107 "c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1108 "dp=" PTR_FORMAT " cdw=" SIZE_FORMAT_W(8),
1109 sd.region(cp), p2i(region_destination),
1110 p2i(dense_prefix), cur_deadwood);
1111
1112 if (cur_deadwood >= deadwood_goal) {
1113 // Found the region that has the correct amount of deadwood to the left.
1114 // This typically occurs after crossing a fairly sparse set of regions, so
1115 // iterate backwards over those sparse regions, looking for the region
1116 // that has the lowest density of live objects 'to the right.'
1117 size_t space_to_left = sd.region(cp) * region_size;
1118 size_t live_to_left = space_to_left - cur_deadwood;
1119 size_t space_to_right = space_capacity - space_to_left;
1120 size_t live_to_right = space_live - live_to_left;
1121 double density_to_right = double(live_to_right) / space_to_right;
1122 while (cp > full_cp) {
1123 --cp;
1124 const size_t prev_region_live_to_right = live_to_right -
1125 cp->data_size();
1126 const size_t prev_region_space_to_right = space_to_right + region_size;
1127 double prev_region_density_to_right =
1128 double(prev_region_live_to_right) / prev_region_space_to_right;
1129 if (density_to_right <= prev_region_density_to_right) {
1130 return dense_prefix;
1131 }
1132
1133 log_develop_trace(gc, compaction)(
1134 "backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1135 "pc_d2r=%10.8f",
1136 sd.region(cp), density_to_right,
1137 prev_region_density_to_right);
1138
1139 dense_prefix -= region_size;
1140 live_to_right = prev_region_live_to_right;
1141 space_to_right = prev_region_space_to_right;
1142 density_to_right = prev_region_density_to_right;
1143 }
1144 return dense_prefix;
1145 }
1146
1147 dense_prefix += region_size;
1148 ++cp;
1149 }
1150
1151 return dense_prefix;
1152 }
1153
1154 #ifndef PRODUCT
1155 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1156 const SpaceId id,
1157 const bool maximum_compaction,
1158 HeapWord* const addr)
1159 {
1160 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1161 RegionData* const cp = summary_data().region(region_idx);
1162 const MutableSpace* const space = _space_info[id].space();
1163 HeapWord* const new_top = _space_info[id].new_top();
1164
1165 const size_t space_live = pointer_delta(new_top, space->bottom());
1166 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1167 const size_t space_cap = space->capacity_in_words();
1168 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1169 const size_t live_to_right = new_top - cp->destination();
1170 const size_t dead_to_right = space->top() - addr - live_to_right;
1171
1172 log_develop_debug(gc, compaction)(
1173 "%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1174 "spl=" SIZE_FORMAT " "
1175 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1176 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT " "
1177 "ratio=%10.8f",
1178 algorithm, p2i(addr), region_idx,
1179 space_live,
1180 dead_to_left, dead_to_left_pct,
1181 dead_to_right, live_to_right,
1182 double(dead_to_right) / live_to_right);
1183 }
1184 #endif // #ifndef PRODUCT
1185
1186 // Return a fraction indicating how much of the generation can be treated as
1187 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1188 // based on the density of live objects in the generation to determine a limit,
1189 // which is then adjusted so the return value is min_percent when the density is
1190 // 1.
1191 //
1192 // The following table shows some return values for a different values of the
1193 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1194 // min_percent is 1.
1195 //
1196 // fraction allowed as dead wood
1197 // -----------------------------------------------------------------
1198 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1199 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1200 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1201 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1202 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1203 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1204 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1205 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1206 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1207 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1208 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1209 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1210 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1211 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1212 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1213 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1214 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1215 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1216 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1217 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1218 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1219 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1220 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1221
1222 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1223 {
1224 assert(_dwl_initialized, "uninitialized");
1225
1226 // The raw limit is the value of the normal distribution at x = density.
1227 const double raw_limit = normal_distribution(density);
1228
1229 // Adjust the raw limit so it becomes the minimum when the density is 1.
1230 //
1231 // First subtract the adjustment value (which is simply the precomputed value
1232 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1233 // Then add the minimum value, so the minimum is returned when the density is
1234 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1235 const double min = double(min_percent) / 100.0;
1236 const double limit = raw_limit - _dwl_adjustment + min;
1237 return MAX2(limit, 0.0);
1238 }
1239
1240 ParallelCompactData::RegionData*
1241 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1242 const RegionData* end)
1243 {
1244 const size_t region_size = ParallelCompactData::RegionSize;
1245 ParallelCompactData& sd = summary_data();
1246 size_t left = sd.region(beg);
1247 size_t right = end > beg ? sd.region(end) - 1 : left;
1248
1249 // Binary search.
1250 while (left < right) {
1251 // Equivalent to (left + right) / 2, but does not overflow.
1252 const size_t middle = left + (right - left) / 2;
1253 RegionData* const middle_ptr = sd.region(middle);
1254 HeapWord* const dest = middle_ptr->destination();
1255 HeapWord* const addr = sd.region_to_addr(middle);
1256 assert(dest != NULL, "sanity");
1257 assert(dest <= addr, "must move left");
1258
1259 if (middle > left && dest < addr) {
1260 right = middle - 1;
1261 } else if (middle < right && middle_ptr->data_size() == region_size) {
1262 left = middle + 1;
1263 } else {
1264 return middle_ptr;
1265 }
1266 }
1267 return sd.region(left);
1268 }
1269
1270 ParallelCompactData::RegionData*
1271 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1272 const RegionData* end,
1273 size_t dead_words)
1274 {
1275 ParallelCompactData& sd = summary_data();
1276 size_t left = sd.region(beg);
1277 size_t right = end > beg ? sd.region(end) - 1 : left;
1278
1279 // Binary search.
1280 while (left < right) {
1281 // Equivalent to (left + right) / 2, but does not overflow.
1282 const size_t middle = left + (right - left) / 2;
1283 RegionData* const middle_ptr = sd.region(middle);
1284 HeapWord* const dest = middle_ptr->destination();
1285 HeapWord* const addr = sd.region_to_addr(middle);
1286 assert(dest != NULL, "sanity");
1287 assert(dest <= addr, "must move left");
1288
1289 const size_t dead_to_left = pointer_delta(addr, dest);
1290 if (middle > left && dead_to_left > dead_words) {
1291 right = middle - 1;
1292 } else if (middle < right && dead_to_left < dead_words) {
1293 left = middle + 1;
1294 } else {
1295 return middle_ptr;
1296 }
1297 }
1298 return sd.region(left);
1299 }
1300
1301 // The result is valid during the summary phase, after the initial summarization
1302 // of each space into itself, and before final summarization.
1303 inline double
1304 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1305 HeapWord* const bottom,
1306 HeapWord* const top,
1307 HeapWord* const new_top)
1308 {
1309 ParallelCompactData& sd = summary_data();
1310
1311 assert(cp != NULL, "sanity");
1312 assert(bottom != NULL, "sanity");
1313 assert(top != NULL, "sanity");
1314 assert(new_top != NULL, "sanity");
1315 assert(top >= new_top, "summary data problem?");
1316 assert(new_top > bottom, "space is empty; should not be here");
1317 assert(new_top >= cp->destination(), "sanity");
1318 assert(top >= sd.region_to_addr(cp), "sanity");
1319
1320 HeapWord* const destination = cp->destination();
1321 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1322 const size_t compacted_region_live = pointer_delta(new_top, destination);
1323 const size_t compacted_region_used = pointer_delta(top,
1324 sd.region_to_addr(cp));
1325 const size_t reclaimable = compacted_region_used - compacted_region_live;
1326
1327 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1328 return double(reclaimable) / divisor;
1329 }
1330
1331 // Return the address of the end of the dense prefix, a.k.a. the start of the
1332 // compacted region. The address is always on a region boundary.
1333 //
1334 // Completely full regions at the left are skipped, since no compaction can
1335 // occur in those regions. Then the maximum amount of dead wood to allow is
1336 // computed, based on the density (amount live / capacity) of the generation;
1337 // the region with approximately that amount of dead space to the left is
1338 // identified as the limit region. Regions between the last completely full
1339 // region and the limit region are scanned and the one that has the best
1340 // (maximum) reclaimed_ratio() is selected.
1341 HeapWord*
1342 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1343 bool maximum_compaction)
1344 {
1345 const size_t region_size = ParallelCompactData::RegionSize;
1346 const ParallelCompactData& sd = summary_data();
1347
1348 const MutableSpace* const space = _space_info[id].space();
1349 HeapWord* const top = space->top();
1350 HeapWord* const top_aligned_up = sd.region_align_up(top);
1351 HeapWord* const new_top = _space_info[id].new_top();
1352 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1353 HeapWord* const bottom = space->bottom();
1354 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1355 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1356 const RegionData* const new_top_cp =
1357 sd.addr_to_region_ptr(new_top_aligned_up);
1358
1359 // Skip full regions at the beginning of the space--they are necessarily part
1360 // of the dense prefix.
1361 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1362 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1363 space->is_empty(), "no dead space allowed to the left");
1364 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1365 "region must have dead space");
1366
1367 // The gc number is saved whenever a maximum compaction is done, and used to
1368 // determine when the maximum compaction interval has expired. This avoids
1369 // successive max compactions for different reasons.
1370 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1371 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1372 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1373 total_invocations() == HeapFirstMaximumCompactionCount;
1374 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1375 _maximum_compaction_gc_num = total_invocations();
1376 return sd.region_to_addr(full_cp);
1377 }
1378
1379 const size_t space_live = pointer_delta(new_top, bottom);
1380 const size_t space_used = space->used_in_words();
1381 const size_t space_capacity = space->capacity_in_words();
1382
1383 const double density = double(space_live) / double(space_capacity);
1384 const size_t min_percent_free = MarkSweepDeadRatio;
1385 const double limiter = dead_wood_limiter(density, min_percent_free);
1386 const size_t dead_wood_max = space_used - space_live;
1387 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1388 dead_wood_max);
1389
1390 log_develop_debug(gc, compaction)(
1391 "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " "
1392 "space_cap=" SIZE_FORMAT,
1393 space_live, space_used,
1394 space_capacity);
1395 log_develop_debug(gc, compaction)(
1396 "dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1397 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1398 density, min_percent_free, limiter,
1399 dead_wood_max, dead_wood_limit);
1400
1401 // Locate the region with the desired amount of dead space to the left.
1402 const RegionData* const limit_cp =
1403 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1404
1405 // Scan from the first region with dead space to the limit region and find the
1406 // one with the best (largest) reclaimed ratio.
1407 double best_ratio = 0.0;
1408 const RegionData* best_cp = full_cp;
1409 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1410 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1411 if (tmp_ratio > best_ratio) {
1412 best_cp = cp;
1413 best_ratio = tmp_ratio;
1414 }
1415 }
1416
1417 return sd.region_to_addr(best_cp);
1418 }
1419
1420 void PSParallelCompact::summarize_spaces_quick()
1421 {
1422 for (unsigned int i = 0; i < last_space_id; ++i) {
1423 const MutableSpace* space = _space_info[i].space();
1424 HeapWord** nta = _space_info[i].new_top_addr();
1425 bool result = _summary_data.summarize(_space_info[i].split_info(),
1426 space->bottom(), space->top(), NULL,
1427 space->bottom(), space->end(), nta);
1428 assert(result, "space must fit into itself");
1429 _space_info[i].set_dense_prefix(space->bottom());
1430 }
1431 }
1432
1433 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1434 {
1435 HeapWord* const dense_prefix_end = dense_prefix(id);
1436 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1437 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1438 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1439 // Only enough dead space is filled so that any remaining dead space to the
1440 // left is larger than the minimum filler object. (The remainder is filled
1441 // during the copy/update phase.)
1442 //
1443 // The size of the dead space to the right of the boundary is not a
1444 // concern, since compaction will be able to use whatever space is
1445 // available.
1446 //
1447 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1448 // surrounds the space to be filled with an object.
1449 //
1450 // In the 32-bit VM, each bit represents two 32-bit words:
1451 // +---+
1452 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1453 // end_bits: ... x x x | 0 | || 0 x x ...
1454 // +---+
1455 //
1456 // In the 64-bit VM, each bit represents one 64-bit word:
1457 // +------------+
1458 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1459 // end_bits: ... x x 1 | 0 || 0 | x x ...
1460 // +------------+
1461 // +-------+
1462 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1463 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1464 // +-------+
1465 // +-----------+
1466 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1467 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1468 // +-----------+
1469 // +-------+
1470 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1471 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1472 // +-------+
1473
1474 // Initially assume case a, c or e will apply.
1475 size_t obj_len = CollectedHeap::min_fill_size();
1476 HeapWord* obj_beg = dense_prefix_end - obj_len;
1477
1478 #ifdef _LP64
1479 if (MinObjAlignment > 1) { // object alignment > heap word size
1480 // Cases a, c or e.
1481 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1482 // Case b above.
1483 obj_beg = dense_prefix_end - 1;
1484 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1485 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1486 // Case d above.
1487 obj_beg = dense_prefix_end - 3;
1488 obj_len = 3;
1489 }
1490 #endif // #ifdef _LP64
1491
1492 CollectedHeap::fill_with_object(obj_beg, obj_len);
1493 _mark_bitmap.mark_obj(obj_beg, obj_len);
1494 _summary_data.add_obj(obj_beg, obj_len);
1495 assert(start_array(id) != NULL, "sanity");
1496 start_array(id)->allocate_block(obj_beg);
1497 }
1498 }
1499
1500 void
1501 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1502 {
1503 assert(id < last_space_id, "id out of range");
1504 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1505 "should have been reset in summarize_spaces_quick()");
1506
1507 const MutableSpace* space = _space_info[id].space();
1508 if (_space_info[id].new_top() != space->bottom()) {
1509 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1510 _space_info[id].set_dense_prefix(dense_prefix_end);
1511
1512 #ifndef PRODUCT
1513 if (log_is_enabled(Debug, gc, compaction)) {
1514 print_dense_prefix_stats("ratio", id, maximum_compaction,
1515 dense_prefix_end);
1516 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1517 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1518 }
1519 #endif // #ifndef PRODUCT
1520
1521 // Recompute the summary data, taking into account the dense prefix. If
1522 // every last byte will be reclaimed, then the existing summary data which
1523 // compacts everything can be left in place.
1524 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1525 // If dead space crosses the dense prefix boundary, it is (at least
1526 // partially) filled with a dummy object, marked live and added to the
1527 // summary data. This simplifies the copy/update phase and must be done
1528 // before the final locations of objects are determined, to prevent
1529 // leaving a fragment of dead space that is too small to fill.
1530 fill_dense_prefix_end(id);
1531
1532 // Compute the destination of each Region, and thus each object.
1533 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1534 _summary_data.summarize(_space_info[id].split_info(),
1535 dense_prefix_end, space->top(), NULL,
1536 dense_prefix_end, space->end(),
1537 _space_info[id].new_top_addr());
1538 }
1539 }
1540
1541 if (log_develop_is_enabled(Trace, gc, compaction)) {
1542 const size_t region_size = ParallelCompactData::RegionSize;
1543 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1544 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1545 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1546 HeapWord* const new_top = _space_info[id].new_top();
1547 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1548 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1549 log_develop_trace(gc, compaction)(
1550 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1551 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1552 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1553 id, space->capacity_in_words(), p2i(dense_prefix_end),
1554 dp_region, dp_words / region_size,
1555 cr_words / region_size, p2i(new_top));
1556 }
1557 }
1558
1559 #ifndef PRODUCT
1560 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1561 HeapWord* dst_beg, HeapWord* dst_end,
1562 SpaceId src_space_id,
1563 HeapWord* src_beg, HeapWord* src_end)
1564 {
1565 log_develop_trace(gc, compaction)(
1566 "Summarizing %d [%s] into %d [%s]: "
1567 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1568 SIZE_FORMAT "-" SIZE_FORMAT " "
1569 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1570 SIZE_FORMAT "-" SIZE_FORMAT,
1571 src_space_id, space_names[src_space_id],
1572 dst_space_id, space_names[dst_space_id],
1573 p2i(src_beg), p2i(src_end),
1574 _summary_data.addr_to_region_idx(src_beg),
1575 _summary_data.addr_to_region_idx(src_end),
1576 p2i(dst_beg), p2i(dst_end),
1577 _summary_data.addr_to_region_idx(dst_beg),
1578 _summary_data.addr_to_region_idx(dst_end));
1579 }
1580 #endif // #ifndef PRODUCT
1581
1582 void PSParallelCompact::summary_phase(bool maximum_compaction)
1583 {
1584 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1585
1586 // Quick summarization of each space into itself, to see how much is live.
1587 summarize_spaces_quick();
1588
1589 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1590 NOT_PRODUCT(print_region_ranges());
1591 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1592
1593 // The amount of live data that will end up in old space (assuming it fits).
1594 size_t old_space_total_live = 0;
1595 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1596 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1597 _space_info[id].space()->bottom());
1598 }
1599
1600 MutableSpace* const old_space = _space_info[old_space_id].space();
1601 const size_t old_capacity = old_space->capacity_in_words();
1602 if (old_space_total_live > old_capacity) {
1603 // XXX - should also try to expand
1604 maximum_compaction = true;
1605 }
1606
1607 // Old generations.
1608 summarize_space(old_space_id, maximum_compaction);
1609
1610 // Summarize the remaining spaces in the young gen. The initial target space
1611 // is the old gen. If a space does not fit entirely into the target, then the
1612 // remainder is compacted into the space itself and that space becomes the new
1613 // target.
1614 SpaceId dst_space_id = old_space_id;
1615 HeapWord* dst_space_end = old_space->end();
1616 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1617 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1618 const MutableSpace* space = _space_info[id].space();
1619 const size_t live = pointer_delta(_space_info[id].new_top(),
1620 space->bottom());
1621 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1622
1623 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1624 SpaceId(id), space->bottom(), space->top());)
1625 if (live > 0 && live <= available) {
1626 // All the live data will fit.
1627 bool done = _summary_data.summarize(_space_info[id].split_info(),
1628 space->bottom(), space->top(),
1629 NULL,
1630 *new_top_addr, dst_space_end,
1631 new_top_addr);
1632 assert(done, "space must fit into old gen");
1633
1634 // Reset the new_top value for the space.
1635 _space_info[id].set_new_top(space->bottom());
1636 } else if (live > 0) {
1637 // Attempt to fit part of the source space into the target space.
1638 HeapWord* next_src_addr = NULL;
1639 bool done = _summary_data.summarize(_space_info[id].split_info(),
1640 space->bottom(), space->top(),
1641 &next_src_addr,
1642 *new_top_addr, dst_space_end,
1643 new_top_addr);
1644 assert(!done, "space should not fit into old gen");
1645 assert(next_src_addr != NULL, "sanity");
1646
1647 // The source space becomes the new target, so the remainder is compacted
1648 // within the space itself.
1649 dst_space_id = SpaceId(id);
1650 dst_space_end = space->end();
1651 new_top_addr = _space_info[id].new_top_addr();
1652 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1653 space->bottom(), dst_space_end,
1654 SpaceId(id), next_src_addr, space->top());)
1655 done = _summary_data.summarize(_space_info[id].split_info(),
1656 next_src_addr, space->top(),
1657 NULL,
1658 space->bottom(), dst_space_end,
1659 new_top_addr);
1660 assert(done, "space must fit when compacted into itself");
1661 assert(*new_top_addr <= space->top(), "usage should not grow");
1662 }
1663 }
1664
1665 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1666 NOT_PRODUCT(print_region_ranges());
1667 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1668 }
1669
1670 // This method should contain all heap-specific policy for invoking a full
1671 // collection. invoke_no_policy() will only attempt to compact the heap; it
1672 // will do nothing further. If we need to bail out for policy reasons, scavenge
1673 // before full gc, or any other specialized behavior, it needs to be added here.
1674 //
1675 // Note that this method should only be called from the vm_thread while at a
1676 // safepoint.
1677 //
1678 // Note that the all_soft_refs_clear flag in the soft ref policy
1679 // may be true because this method can be called without intervening
1680 // activity. For example when the heap space is tight and full measure
1681 // are being taken to free space.
1682 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1683 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1684 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1685 "should be in vm thread");
1686
1687 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1688 assert(!heap->is_gc_active(), "not reentrant");
1689
1690 IsGCActiveMark mark;
1691
1692 if (ScavengeBeforeFullGC) {
1693 PSScavenge::invoke_no_policy();
1694 }
1695
1696 const bool clear_all_soft_refs =
1697 heap->soft_ref_policy()->should_clear_all_soft_refs();
1698
1699 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1700 maximum_heap_compaction);
1701 }
1702
1703 // This method contains no policy. You should probably
1704 // be calling invoke() instead.
1705 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1706 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1707 assert(ref_processor() != NULL, "Sanity");
1708
1709 if (GCLocker::check_active_before_gc()) {
1710 return false;
1711 }
1712
1713 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1714
1715 GCIdMark gc_id_mark;
1716 _gc_timer.register_gc_start();
1717 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1718
1719 GCCause::Cause gc_cause = heap->gc_cause();
1720 PSYoungGen* young_gen = heap->young_gen();
1721 PSOldGen* old_gen = heap->old_gen();
1722 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1723
1724 // The scope of casr should end after code that can change
1725 // SoftRefPolicy::_should_clear_all_soft_refs.
1726 ClearedAllSoftRefs casr(maximum_heap_compaction,
1727 heap->soft_ref_policy());
1728
1729 if (ZapUnusedHeapArea) {
1730 // Save information needed to minimize mangling
1731 heap->record_gen_tops_before_GC();
1732 }
1733
1734 // Make sure data structures are sane, make the heap parsable, and do other
1735 // miscellaneous bookkeeping.
1736 pre_compact();
1737
1738 const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
1739
1740 {
1741 const uint active_workers =
1742 WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().max_workers(),
1743 ParallelScavengeHeap::heap()->workers().active_workers(),
1744 Threads::number_of_non_daemon_threads());
1745 ParallelScavengeHeap::heap()->workers().set_active_workers(active_workers);
1746
1747 GCTraceCPUTime tcpu(&_gc_tracer);
1748 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1749
1750 heap->pre_full_gc_dump(&_gc_timer);
1751
1752 TraceCollectorStats tcs(counters());
1753 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause);
1754
1755 if (log_is_enabled(Debug, gc, heap, exit)) {
1756 accumulated_time()->start();
1757 }
1758
1759 // Let the size policy know we're starting
1760 size_policy->major_collection_begin();
1761
1762 #if COMPILER2_OR_JVMCI
1763 DerivedPointerTable::clear();
1764 #endif
1765
1766 ref_processor()->start_discovery(maximum_heap_compaction);
1767
1768 marking_phase(&_gc_tracer);
1769
1770 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1771 && GCCause::is_user_requested_gc(gc_cause);
1772 summary_phase(maximum_heap_compaction || max_on_system_gc);
1773
1774 #if COMPILER2_OR_JVMCI
1775 assert(DerivedPointerTable::is_active(), "Sanity");
1776 DerivedPointerTable::set_active(false);
1777 #endif
1778
1779 // adjust_roots() updates Universe::_intArrayKlassObj which is
1780 // needed by the compaction for filling holes in the dense prefix.
1781 adjust_roots();
1782
1783 compact();
1784
1785 ParCompactionManager::verify_all_region_stack_empty();
1786
1787 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1788 // done before resizing.
1789 post_compact();
1790
1791 // Let the size policy know we're done
1792 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1793
1794 if (UseAdaptiveSizePolicy) {
1795 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1796 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1797 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1798
1799 // Don't check if the size_policy is ready here. Let
1800 // the size_policy check that internally.
1801 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1802 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1803 // Swap the survivor spaces if from_space is empty. The
1804 // resize_young_gen() called below is normally used after
1805 // a successful young GC and swapping of survivor spaces;
1806 // otherwise, it will fail to resize the young gen with
1807 // the current implementation.
1808 if (young_gen->from_space()->is_empty()) {
1809 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1810 young_gen->swap_spaces();
1811 }
1812
1813 // Calculate optimal free space amounts
1814 assert(young_gen->max_gen_size() >
1815 young_gen->from_space()->capacity_in_bytes() +
1816 young_gen->to_space()->capacity_in_bytes(),
1817 "Sizes of space in young gen are out-of-bounds");
1818
1819 size_t young_live = young_gen->used_in_bytes();
1820 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1821 size_t old_live = old_gen->used_in_bytes();
1822 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1823 size_t max_old_gen_size = old_gen->max_gen_size();
1824 size_t max_eden_size = young_gen->max_gen_size() -
1825 young_gen->from_space()->capacity_in_bytes() -
1826 young_gen->to_space()->capacity_in_bytes();
1827
1828 // Used for diagnostics
1829 size_policy->clear_generation_free_space_flags();
1830
1831 size_policy->compute_generations_free_space(young_live,
1832 eden_live,
1833 old_live,
1834 cur_eden,
1835 max_old_gen_size,
1836 max_eden_size,
1837 true /* full gc*/);
1838
1839 size_policy->check_gc_overhead_limit(eden_live,
1840 max_old_gen_size,
1841 max_eden_size,
1842 true /* full gc*/,
1843 gc_cause,
1844 heap->soft_ref_policy());
1845
1846 size_policy->decay_supplemental_growth(true /* full gc*/);
1847
1848 heap->resize_old_gen(
1849 size_policy->calculated_old_free_size_in_bytes());
1850
1851 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1852 size_policy->calculated_survivor_size_in_bytes());
1853 }
1854
1855 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1856 }
1857
1858 if (UsePerfData) {
1859 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1860 counters->update_counters();
1861 counters->update_old_capacity(old_gen->capacity_in_bytes());
1862 counters->update_young_capacity(young_gen->capacity_in_bytes());
1863 }
1864
1865 heap->resize_all_tlabs();
1866
1867 // Resize the metaspace capacity after a collection
1868 MetaspaceGC::compute_new_size();
1869
1870 if (log_is_enabled(Debug, gc, heap, exit)) {
1871 accumulated_time()->stop();
1872 }
1873
1874 heap->print_heap_change(pre_gc_values);
1875
1876 // Track memory usage and detect low memory
1877 MemoryService::track_memory_usage();
1878 heap->update_counters();
1879
1880 heap->post_full_gc_dump(&_gc_timer);
1881 }
1882
1883 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1884 Universe::verify("After GC");
1885 }
1886
1887 // Re-verify object start arrays
1888 if (VerifyObjectStartArray &&
1889 VerifyAfterGC) {
1890 old_gen->verify_object_start_array();
1891 }
1892
1893 if (ZapUnusedHeapArea) {
1894 old_gen->object_space()->check_mangled_unused_area_complete();
1895 }
1896
1897 heap->print_heap_after_gc();
1898 heap->trace_heap_after_gc(&_gc_tracer);
1899
1900 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1901
1902 _gc_timer.register_gc_end();
1903
1904 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1905 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1906
1907 return true;
1908 }
1909
1910 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1911 private:
1912 uint _worker_id;
1913
1914 public:
1915 PCAddThreadRootsMarkingTaskClosure(uint worker_id) : _worker_id(worker_id) { }
1916 void do_thread(Thread* thread) {
1917 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
1918
1919 ResourceMark rm;
1920
1921 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(_worker_id);
1922
1923 PCMarkAndPushClosure mark_and_push_closure(cm);
1924 MarkingCodeBlobClosure mark_and_push_in_blobs(&mark_and_push_closure, !CodeBlobToOopClosure::FixRelocations, true /* keepalive nmethods */);
1925
1926 thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs);
1927
1928 // Do the real work
1929 cm->follow_marking_stacks();
1930 }
1931 };
1932
1933 void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
1934 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
1935
1936 ParCompactionManager* cm =
1937 ParCompactionManager::gc_thread_compaction_manager(worker_id);
1938
1939 do {
1940 oop obj = NULL;
1941 ObjArrayTask task;
1942 if (ParCompactionManager::steal_objarray(worker_id, task)) {
1943 cm->follow_array((objArrayOop)task.obj(), task.index());
1944 } else if (ParCompactionManager::steal(worker_id, obj)) {
1945 cm->follow_contents(obj);
1946 }
1947 cm->follow_marking_stacks();
1948 } while (!terminator.offer_termination());
1949 }
1950
1951 class MarkFromRootsTask : public WorkerTask {
1952 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
1953 OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
1954 TaskTerminator _terminator;
1955 uint _active_workers;
1956
1957 public:
1958 MarkFromRootsTask(uint active_workers) :
1959 WorkerTask("MarkFromRootsTask"),
1960 _strong_roots_scope(active_workers),
1961 _terminator(active_workers, ParCompactionManager::oop_task_queues()),
1962 _active_workers(active_workers) {}
1963
1964 virtual void work(uint worker_id) {
1965 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
1966 PCMarkAndPushClosure mark_and_push_closure(cm);
1967
1968 {
1969 CLDToOopClosure cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_strong);
1970 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
1971
1972 // Do the real work
1973 cm->follow_marking_stacks();
1974 }
1975
1976 PCAddThreadRootsMarkingTaskClosure closure(worker_id);
1977 Threads::possibly_parallel_threads_do(true /*parallel */, &closure);
1978
1979 // Mark from OopStorages
1980 {
1981 _oop_storage_set_par_state.oops_do(&mark_and_push_closure);
1982 // Do the real work
1983 cm->follow_marking_stacks();
1984 }
1985
1986 if (_active_workers > 1) {
1987 steal_marking_work(_terminator, worker_id);
1988 }
1989 }
1990 };
1991
1992 class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
1993 TaskTerminator _terminator;
1994
1995 public:
1996 ParallelCompactRefProcProxyTask(uint max_workers)
1997 : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers),
1998 _terminator(_max_workers, ParCompactionManager::oop_task_queues()) {}
1999
2000 void work(uint worker_id) override {
2001 assert(worker_id < _max_workers, "sanity");
2002 ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
2003 PCMarkAndPushClosure keep_alive(cm);
2004 BarrierEnqueueDiscoveredFieldClosure enqueue;
2005 ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
2006 _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &keep_alive, &enqueue, &complete_gc);
2007 }
2008
2009 void prepare_run_task_hook() override {
2010 _terminator.reset_for_reuse(_queue_count);
2011 }
2012 };
2013
2014 void PSParallelCompact::marking_phase(ParallelOldTracer *gc_tracer) {
2015 // Recursively traverse all live objects and mark them
2016 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2017
2018 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2019
2020 // Need new claim bits before marking starts.
2021 ClassLoaderDataGraph::clear_claimed_marks();
2022
2023 {
2024 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2025
2026 MarkFromRootsTask task(active_gc_threads);
2027 ParallelScavengeHeap::heap()->workers().run_task(&task);
2028 }
2029
2030 // Process reference objects found during marking
2031 {
2032 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2033
2034 ReferenceProcessorStats stats;
2035 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
2036
2037 ref_processor()->set_active_mt_degree(active_gc_threads);
2038 ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues());
2039 stats = ref_processor()->process_discovered_references(task, pt);
2040
2041 gc_tracer->report_gc_reference_stats(stats);
2042 pt.print_all_references();
2043 }
2044
2045 // This is the point where the entire marking should have completed.
2046 ParCompactionManager::verify_all_marking_stack_empty();
2047
2048 {
2049 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
2050 WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(),
2051 is_alive_closure(),
2052 &do_nothing_cl,
2053 1);
2054 }
2055
2056 {
2057 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2058 CodeCache::UnloadingScope scope(is_alive_closure());
2059
2060 // Follow system dictionary roots and unload classes.
2061 bool purged_class = SystemDictionary::do_unloading(&_gc_timer);
2062
2063 // Unload nmethods.
2064 CodeCache::do_unloading(purged_class);
2065
2066 // Prune dead klasses from subklass/sibling/implementor lists.
2067 Klass::clean_weak_klass_links(purged_class);
2068
2069 // Clean JVMCI metadata handles.
2070 JVMCI_ONLY(JVMCI::do_unloading(purged_class));
2071 }
2072
2073 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2074 #if TASKQUEUE_STATS
2075 ParCompactionManager::oop_task_queues()->print_and_reset_taskqueue_stats("Oop Queue");
2076 ParCompactionManager::_objarray_task_queues->print_and_reset_taskqueue_stats("ObjArrayOop Queue");
2077 #endif
2078 }
2079
2080 class PSAdjustTask final : public WorkerTask {
2081 SubTasksDone _sub_tasks;
2082 WeakProcessor::Task _weak_proc_task;
2083 OopStorageSetStrongParState<false, false> _oop_storage_iter;
2084 uint _nworkers;
2085
2086 enum PSAdjustSubTask {
2087 PSAdjustSubTask_code_cache,
2088
2089 PSAdjustSubTask_num_elements
2090 };
2091
2092 public:
2093 PSAdjustTask(uint nworkers) :
2094 WorkerTask("PSAdjust task"),
2095 _sub_tasks(PSAdjustSubTask_num_elements),
2096 _weak_proc_task(nworkers),
2097 _nworkers(nworkers) {
2098 // Need new claim bits when tracing through and adjusting pointers.
2099 ClassLoaderDataGraph::clear_claimed_marks();
2100 if (nworkers > 1) {
2101 Threads::change_thread_claim_token();
2102 }
2103 }
2104
2105 ~PSAdjustTask() {
2106 Threads::assert_all_threads_claimed();
2107 }
2108
2109 void work(uint worker_id) {
2110 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2111 PCAdjustPointerClosure adjust(cm);
2112 {
2113 ResourceMark rm;
2114 Threads::possibly_parallel_oops_do(_nworkers > 1, &adjust, nullptr);
2115 }
2116 _oop_storage_iter.oops_do(&adjust);
2117 {
2118 CLDToOopClosure cld_closure(&adjust, ClassLoaderData::_claim_strong);
2119 ClassLoaderDataGraph::cld_do(&cld_closure);
2120 }
2121 {
2122 AlwaysTrueClosure always_alive;
2123 _weak_proc_task.work(worker_id, &always_alive, &adjust);
2124 }
2125 if (_sub_tasks.try_claim_task(PSAdjustSubTask_code_cache)) {
2126 CodeBlobToOopClosure adjust_code(&adjust, CodeBlobToOopClosure::FixRelocations);
2127 CodeCache::blobs_do(&adjust_code);
2128 }
2129 _sub_tasks.all_tasks_claimed();
2130 }
2131 };
2132
2133 void PSParallelCompact::adjust_roots() {
2134 // Adjust the pointers to reflect the new locations
2135 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2136 uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
2137 PSAdjustTask task(nworkers);
2138 ParallelScavengeHeap::heap()->workers().run_task(&task);
2139 }
2140
2141 // Helper class to print 8 region numbers per line and then print the total at the end.
2142 class FillableRegionLogger : public StackObj {
2143 private:
2144 Log(gc, compaction) log;
2145 static const int LineLength = 8;
2146 size_t _regions[LineLength];
2147 int _next_index;
2148 bool _enabled;
2149 size_t _total_regions;
2150 public:
2151 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
2152 ~FillableRegionLogger() {
2153 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2154 }
2155
2156 void print_line() {
2157 if (!_enabled || _next_index == 0) {
2158 return;
2159 }
2160 FormatBuffer<> line("Fillable: ");
2161 for (int i = 0; i < _next_index; i++) {
2162 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2163 }
2164 log.trace("%s", line.buffer());
2165 _next_index = 0;
2166 }
2167
2168 void handle(size_t region) {
2169 if (!_enabled) {
2170 return;
2171 }
2172 _regions[_next_index++] = region;
2173 if (_next_index == LineLength) {
2174 print_line();
2175 }
2176 _total_regions++;
2177 }
2178 };
2179
2180 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
2181 {
2182 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2183
2184 // Find the threads that are active
2185 uint worker_id = 0;
2186
2187 // Find all regions that are available (can be filled immediately) and
2188 // distribute them to the thread stacks. The iteration is done in reverse
2189 // order (high to low) so the regions will be removed in ascending order.
2190
2191 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2192
2193 // id + 1 is used to test termination so unsigned can
2194 // be used with an old_space_id == 0.
2195 FillableRegionLogger region_logger;
2196 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2197 SpaceInfo* const space_info = _space_info + id;
2198 HeapWord* const new_top = space_info->new_top();
2199
2200 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2201 const size_t end_region =
2202 sd.addr_to_region_idx(sd.region_align_up(new_top));
2203
2204 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2205 if (sd.region(cur)->claim_unsafe()) {
2206 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2207 bool result = sd.region(cur)->mark_normal();
2208 assert(result, "Must succeed at this point.");
2209 cm->region_stack()->push(cur);
2210 region_logger.handle(cur);
2211 // Assign regions to tasks in round-robin fashion.
2212 if (++worker_id == parallel_gc_threads) {
2213 worker_id = 0;
2214 }
2215 }
2216 }
2217 region_logger.print_line();
2218 }
2219 }
2220
2221 class TaskQueue : StackObj {
2222 volatile uint _counter;
2223 uint _size;
2224 uint _insert_index;
2225 PSParallelCompact::UpdateDensePrefixTask* _backing_array;
2226 public:
2227 explicit TaskQueue(uint size) : _counter(0), _size(size), _insert_index(0), _backing_array(NULL) {
2228 _backing_array = NEW_C_HEAP_ARRAY(PSParallelCompact::UpdateDensePrefixTask, _size, mtGC);
2229 }
2230 ~TaskQueue() {
2231 assert(_counter >= _insert_index, "not all queue elements were claimed");
2232 FREE_C_HEAP_ARRAY(T, _backing_array);
2233 }
2234
2235 void push(const PSParallelCompact::UpdateDensePrefixTask& value) {
2236 assert(_insert_index < _size, "too small backing array");
2237 _backing_array[_insert_index++] = value;
2238 }
2239
2240 bool try_claim(PSParallelCompact::UpdateDensePrefixTask& reference) {
2241 uint claimed = Atomic::fetch_and_add(&_counter, 1u);
2242 if (claimed < _insert_index) {
2243 reference = _backing_array[claimed];
2244 return true;
2245 } else {
2246 return false;
2247 }
2248 }
2249 };
2250
2251 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2252
2253 void PSParallelCompact::enqueue_dense_prefix_tasks(TaskQueue& task_queue,
2254 uint parallel_gc_threads) {
2255 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2256
2257 ParallelCompactData& sd = PSParallelCompact::summary_data();
2258
2259 // Iterate over all the spaces adding tasks for updating
2260 // regions in the dense prefix. Assume that 1 gc thread
2261 // will work on opening the gaps and the remaining gc threads
2262 // will work on the dense prefix.
2263 unsigned int space_id;
2264 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2265 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2266 const MutableSpace* const space = _space_info[space_id].space();
2267
2268 if (dense_prefix_end == space->bottom()) {
2269 // There is no dense prefix for this space.
2270 continue;
2271 }
2272
2273 // The dense prefix is before this region.
2274 size_t region_index_end_dense_prefix =
2275 sd.addr_to_region_idx(dense_prefix_end);
2276 RegionData* const dense_prefix_cp =
2277 sd.region(region_index_end_dense_prefix);
2278 assert(dense_prefix_end == space->end() ||
2279 dense_prefix_cp->available() ||
2280 dense_prefix_cp->claimed(),
2281 "The region after the dense prefix should always be ready to fill");
2282
2283 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2284
2285 // Is there dense prefix work?
2286 size_t total_dense_prefix_regions =
2287 region_index_end_dense_prefix - region_index_start;
2288 // How many regions of the dense prefix should be given to
2289 // each thread?
2290 if (total_dense_prefix_regions > 0) {
2291 uint tasks_for_dense_prefix = 1;
2292 if (total_dense_prefix_regions <=
2293 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2294 // Don't over partition. This assumes that
2295 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2296 // so there are not many regions to process.
2297 tasks_for_dense_prefix = parallel_gc_threads;
2298 } else {
2299 // Over partition
2300 tasks_for_dense_prefix = parallel_gc_threads *
2301 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2302 }
2303 size_t regions_per_thread = total_dense_prefix_regions /
2304 tasks_for_dense_prefix;
2305 // Give each thread at least 1 region.
2306 if (regions_per_thread == 0) {
2307 regions_per_thread = 1;
2308 }
2309
2310 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2311 if (region_index_start >= region_index_end_dense_prefix) {
2312 break;
2313 }
2314 // region_index_end is not processed
2315 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2316 region_index_end_dense_prefix);
2317 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
2318 region_index_start,
2319 region_index_end));
2320 region_index_start = region_index_end;
2321 }
2322 }
2323 // This gets any part of the dense prefix that did not
2324 // fit evenly.
2325 if (region_index_start < region_index_end_dense_prefix) {
2326 task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
2327 region_index_start,
2328 region_index_end_dense_prefix));
2329 }
2330 }
2331 }
2332
2333 #ifdef ASSERT
2334 // Write a histogram of the number of times the block table was filled for a
2335 // region.
2336 void PSParallelCompact::write_block_fill_histogram()
2337 {
2338 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2339 return;
2340 }
2341
2342 Log(gc, compaction) log;
2343 ResourceMark rm;
2344 LogStream ls(log.trace());
2345 outputStream* out = &ls;
2346
2347 typedef ParallelCompactData::RegionData rd_t;
2348 ParallelCompactData& sd = summary_data();
2349
2350 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2351 MutableSpace* const spc = _space_info[id].space();
2352 if (spc->bottom() != spc->top()) {
2353 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2354 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2355 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2356
2357 size_t histo[5] = { 0, 0, 0, 0, 0 };
2358 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2359 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2360
2361 for (const rd_t* cur = beg; cur < end; ++cur) {
2362 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2363 }
2364 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2365 for (size_t i = 0; i < histo_len; ++i) {
2366 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2367 histo[i], 100.0 * histo[i] / region_cnt);
2368 }
2369 out->cr();
2370 }
2371 }
2372 }
2373 #endif // #ifdef ASSERT
2374
2375 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
2376 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2377
2378 ParCompactionManager* cm =
2379 ParCompactionManager::gc_thread_compaction_manager(worker_id);
2380
2381 // Drain the stacks that have been preloaded with regions
2382 // that are ready to fill.
2383
2384 cm->drain_region_stacks();
2385
2386 guarantee(cm->region_stack()->is_empty(), "Not empty");
2387
2388 size_t region_index = 0;
2389
2390 while (true) {
2391 if (ParCompactionManager::steal(worker_id, region_index)) {
2392 PSParallelCompact::fill_and_update_region(cm, region_index);
2393 cm->drain_region_stacks();
2394 } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
2395 // Fill and update an unavailable region with the help of a shadow region
2396 PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
2397 cm->drain_region_stacks();
2398 } else {
2399 if (terminator->offer_termination()) {
2400 break;
2401 }
2402 // Go around again.
2403 }
2404 }
2405 }
2406
2407 class UpdateDensePrefixAndCompactionTask: public WorkerTask {
2408 TaskQueue& _tq;
2409 TaskTerminator _terminator;
2410
2411 public:
2412 UpdateDensePrefixAndCompactionTask(TaskQueue& tq, uint active_workers) :
2413 WorkerTask("UpdateDensePrefixAndCompactionTask"),
2414 _tq(tq),
2415 _terminator(active_workers, ParCompactionManager::region_task_queues()) {
2416 }
2417 virtual void work(uint worker_id) {
2418 ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2419
2420 for (PSParallelCompact::UpdateDensePrefixTask task; _tq.try_claim(task); /* empty */) {
2421 PSParallelCompact::update_and_deadwood_in_dense_prefix(cm,
2422 task._space_id,
2423 task._region_index_start,
2424 task._region_index_end);
2425 }
2426
2427 // Once a thread has drained it's stack, it should try to steal regions from
2428 // other threads.
2429 compaction_with_stealing_work(&_terminator, worker_id);
2430
2431 // At this point all regions have been compacted, so it's now safe
2432 // to update the deferred objects that cross region boundaries.
2433 cm->drain_deferred_objects();
2434 }
2435 };
2436
2437 void PSParallelCompact::compact() {
2438 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2439
2440 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2441 PSOldGen* old_gen = heap->old_gen();
2442 old_gen->start_array()->reset();
2443 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2444
2445 // for [0..last_space_id)
2446 // for [0..active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)
2447 // push
2448 // push
2449 //
2450 // max push count is thus: last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1)
2451 TaskQueue task_queue(last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1));
2452 initialize_shadow_regions(active_gc_threads);
2453 prepare_region_draining_tasks(active_gc_threads);
2454 enqueue_dense_prefix_tasks(task_queue, active_gc_threads);
2455
2456 {
2457 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2458
2459 UpdateDensePrefixAndCompactionTask task(task_queue, active_gc_threads);
2460 ParallelScavengeHeap::heap()->workers().run_task(&task);
2461
2462 #ifdef ASSERT
2463 // Verify that all regions have been processed.
2464 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2465 verify_complete(SpaceId(id));
2466 }
2467 #endif
2468 }
2469
2470 DEBUG_ONLY(write_block_fill_histogram());
2471 }
2472
2473 #ifdef ASSERT
2474 void PSParallelCompact::verify_complete(SpaceId space_id) {
2475 // All Regions between space bottom() to new_top() should be marked as filled
2476 // and all Regions between new_top() and top() should be available (i.e.,
2477 // should have been emptied).
2478 ParallelCompactData& sd = summary_data();
2479 SpaceInfo si = _space_info[space_id];
2480 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2481 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2482 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2483 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2484 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2485
2486 bool issued_a_warning = false;
2487
2488 size_t cur_region;
2489 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2490 const RegionData* const c = sd.region(cur_region);
2491 if (!c->completed()) {
2492 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2493 cur_region, c->destination_count());
2494 issued_a_warning = true;
2495 }
2496 }
2497
2498 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2499 const RegionData* const c = sd.region(cur_region);
2500 if (!c->available()) {
2501 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2502 cur_region, c->destination_count());
2503 issued_a_warning = true;
2504 }
2505 }
2506
2507 if (issued_a_warning) {
2508 print_region_ranges();
2509 }
2510 }
2511 #endif // #ifdef ASSERT
2512
2513 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2514 _start_array->allocate_block(addr);
2515 compaction_manager()->update_contents(cast_to_oop(addr));
2516 }
2517
2518 // Update interior oops in the ranges of regions [beg_region, end_region).
2519 void
2520 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2521 SpaceId space_id,
2522 size_t beg_region,
2523 size_t end_region) {
2524 ParallelCompactData& sd = summary_data();
2525 ParMarkBitMap* const mbm = mark_bitmap();
2526
2527 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2528 HeapWord* const end_addr = sd.region_to_addr(end_region);
2529 assert(beg_region <= end_region, "bad region range");
2530 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2531
2532 #ifdef ASSERT
2533 // Claim the regions to avoid triggering an assert when they are marked as
2534 // filled.
2535 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2536 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2537 }
2538 #endif // #ifdef ASSERT
2539
2540 if (beg_addr != space(space_id)->bottom()) {
2541 // Find the first live object or block of dead space that *starts* in this
2542 // range of regions. If a partial object crosses onto the region, skip it;
2543 // it will be marked for 'deferred update' when the object head is
2544 // processed. If dead space crosses onto the region, it is also skipped; it
2545 // will be filled when the prior region is processed. If neither of those
2546 // apply, the first word in the region is the start of a live object or dead
2547 // space.
2548 assert(beg_addr > space(space_id)->bottom(), "sanity");
2549 const RegionData* const cp = sd.region(beg_region);
2550 if (cp->partial_obj_size() != 0) {
2551 beg_addr = sd.partial_obj_end(beg_region);
2552 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2553 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2554 }
2555 }
2556
2557 if (beg_addr < end_addr) {
2558 // A live object or block of dead space starts in this range of Regions.
2559 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2560
2561 // Create closures and iterate.
2562 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2563 FillClosure fill_closure(cm, space_id);
2564 ParMarkBitMap::IterationStatus status;
2565 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2566 dense_prefix_end);
2567 if (status == ParMarkBitMap::incomplete) {
2568 update_closure.do_addr(update_closure.source());
2569 }
2570 }
2571
2572 // Mark the regions as filled.
2573 RegionData* const beg_cp = sd.region(beg_region);
2574 RegionData* const end_cp = sd.region(end_region);
2575 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2576 cp->set_completed();
2577 }
2578 }
2579
2580 // Return the SpaceId for the space containing addr. If addr is not in the
2581 // heap, last_space_id is returned. In debug mode it expects the address to be
2582 // in the heap and asserts such.
2583 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2584 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2585
2586 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2587 if (_space_info[id].space()->contains(addr)) {
2588 return SpaceId(id);
2589 }
2590 }
2591
2592 assert(false, "no space contains the addr");
2593 return last_space_id;
2594 }
2595
2596 void PSParallelCompact::update_deferred_object(ParCompactionManager* cm, HeapWord *addr) {
2597 #ifdef ASSERT
2598 ParallelCompactData& sd = summary_data();
2599 size_t region_idx = sd.addr_to_region_idx(addr);
2600 assert(sd.region(region_idx)->completed(), "first region must be completed before deferred updates");
2601 assert(sd.region(region_idx + 1)->completed(), "second region must be completed before deferred updates");
2602 #endif
2603
2604 const SpaceInfo* const space_info = _space_info + space_id(addr);
2605 ObjectStartArray* const start_array = space_info->start_array();
2606 if (start_array != NULL) {
2607 start_array->allocate_block(addr);
2608 }
2609
2610 cm->update_contents(cast_to_oop(addr));
2611 assert(oopDesc::is_oop(cast_to_oop(addr)), "Expected an oop at " PTR_FORMAT, p2i(cast_to_oop(addr)));
2612 }
2613
2614 // Skip over count live words starting from beg, and return the address of the
2615 // next live word. Unless marked, the word corresponding to beg is assumed to
2616 // be dead. Callers must either ensure beg does not correspond to the middle of
2617 // an object, or account for those live words in some other way. Callers must
2618 // also ensure that there are enough live words in the range [beg, end) to skip.
2619 HeapWord*
2620 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2621 {
2622 assert(count > 0, "sanity");
2623
2624 ParMarkBitMap* m = mark_bitmap();
2625 idx_t bits_to_skip = m->words_to_bits(count);
2626 idx_t cur_beg = m->addr_to_bit(beg);
2627 const idx_t search_end = m->align_range_end(m->addr_to_bit(end));
2628
2629 do {
2630 cur_beg = m->find_obj_beg(cur_beg, search_end);
2631 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2632 const size_t obj_bits = cur_end - cur_beg + 1;
2633 if (obj_bits > bits_to_skip) {
2634 return m->bit_to_addr(cur_beg + bits_to_skip);
2635 }
2636 bits_to_skip -= obj_bits;
2637 cur_beg = cur_end + 1;
2638 } while (bits_to_skip > 0);
2639
2640 // Skipping the desired number of words landed just past the end of an object.
2641 // Find the start of the next object.
2642 cur_beg = m->find_obj_beg(cur_beg, search_end);
2643 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2644 return m->bit_to_addr(cur_beg);
2645 }
2646
2647 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2648 SpaceId src_space_id,
2649 size_t src_region_idx)
2650 {
2651 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2652
2653 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2654 if (split_info.dest_region_addr() == dest_addr) {
2655 // The partial object ending at the split point contains the first word to
2656 // be copied to dest_addr.
2657 return split_info.first_src_addr();
2658 }
2659
2660 const ParallelCompactData& sd = summary_data();
2661 ParMarkBitMap* const bitmap = mark_bitmap();
2662 const size_t RegionSize = ParallelCompactData::RegionSize;
2663
2664 assert(sd.is_region_aligned(dest_addr), "not aligned");
2665 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2666 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2667 HeapWord* const src_region_destination = src_region_ptr->destination();
2668
2669 assert(dest_addr >= src_region_destination, "wrong src region");
2670 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2671
2672 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2673 HeapWord* const src_region_end = src_region_beg + RegionSize;
2674
2675 HeapWord* addr = src_region_beg;
2676 if (dest_addr == src_region_destination) {
2677 // Return the first live word in the source region.
2678 if (partial_obj_size == 0) {
2679 addr = bitmap->find_obj_beg(addr, src_region_end);
2680 assert(addr < src_region_end, "no objects start in src region");
2681 }
2682 return addr;
2683 }
2684
2685 // Must skip some live data.
2686 size_t words_to_skip = dest_addr - src_region_destination;
2687 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2688
2689 if (partial_obj_size >= words_to_skip) {
2690 // All the live words to skip are part of the partial object.
2691 addr += words_to_skip;
2692 if (partial_obj_size == words_to_skip) {
2693 // Find the first live word past the partial object.
2694 addr = bitmap->find_obj_beg(addr, src_region_end);
2695 assert(addr < src_region_end, "wrong src region");
2696 }
2697 return addr;
2698 }
2699
2700 // Skip over the partial object (if any).
2701 if (partial_obj_size != 0) {
2702 words_to_skip -= partial_obj_size;
2703 addr += partial_obj_size;
2704 }
2705
2706 // Skip over live words due to objects that start in the region.
2707 addr = skip_live_words(addr, src_region_end, words_to_skip);
2708 assert(addr < src_region_end, "wrong src region");
2709 return addr;
2710 }
2711
2712 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2713 SpaceId src_space_id,
2714 size_t beg_region,
2715 HeapWord* end_addr)
2716 {
2717 ParallelCompactData& sd = summary_data();
2718
2719 #ifdef ASSERT
2720 MutableSpace* const src_space = _space_info[src_space_id].space();
2721 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2722 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2723 "src_space_id does not match beg_addr");
2724 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2725 "src_space_id does not match end_addr");
2726 #endif // #ifdef ASSERT
2727
2728 RegionData* const beg = sd.region(beg_region);
2729 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2730
2731 // Regions up to new_top() are enqueued if they become available.
2732 HeapWord* const new_top = _space_info[src_space_id].new_top();
2733 RegionData* const enqueue_end =
2734 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2735
2736 for (RegionData* cur = beg; cur < end; ++cur) {
2737 assert(cur->data_size() > 0, "region must have live data");
2738 cur->decrement_destination_count();
2739 if (cur < enqueue_end && cur->available() && cur->claim()) {
2740 if (cur->mark_normal()) {
2741 cm->push_region(sd.region(cur));
2742 } else if (cur->mark_copied()) {
2743 // Try to copy the content of the shadow region back to its corresponding
2744 // heap region if the shadow region is filled. Otherwise, the GC thread
2745 // fills the shadow region will copy the data back (see
2746 // MoveAndUpdateShadowClosure::complete_region).
2747 copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2748 ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2749 cur->set_completed();
2750 }
2751 }
2752 }
2753 }
2754
2755 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2756 SpaceId& src_space_id,
2757 HeapWord*& src_space_top,
2758 HeapWord* end_addr)
2759 {
2760 typedef ParallelCompactData::RegionData RegionData;
2761
2762 ParallelCompactData& sd = PSParallelCompact::summary_data();
2763 const size_t region_size = ParallelCompactData::RegionSize;
2764
2765 size_t src_region_idx = 0;
2766
2767 // Skip empty regions (if any) up to the top of the space.
2768 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2769 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2770 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2771 const RegionData* const top_region_ptr =
2772 sd.addr_to_region_ptr(top_aligned_up);
2773 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2774 ++src_region_ptr;
2775 }
2776
2777 if (src_region_ptr < top_region_ptr) {
2778 // The next source region is in the current space. Update src_region_idx
2779 // and the source address to match src_region_ptr.
2780 src_region_idx = sd.region(src_region_ptr);
2781 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2782 if (src_region_addr > closure.source()) {
2783 closure.set_source(src_region_addr);
2784 }
2785 return src_region_idx;
2786 }
2787
2788 // Switch to a new source space and find the first non-empty region.
2789 unsigned int space_id = src_space_id + 1;
2790 assert(space_id < last_space_id, "not enough spaces");
2791
2792 HeapWord* const destination = closure.destination();
2793
2794 do {
2795 MutableSpace* space = _space_info[space_id].space();
2796 HeapWord* const bottom = space->bottom();
2797 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2798
2799 // Iterate over the spaces that do not compact into themselves.
2800 if (bottom_cp->destination() != bottom) {
2801 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2802 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2803
2804 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2805 if (src_cp->live_obj_size() > 0) {
2806 // Found it.
2807 assert(src_cp->destination() == destination,
2808 "first live obj in the space must match the destination");
2809 assert(src_cp->partial_obj_size() == 0,
2810 "a space cannot begin with a partial obj");
2811
2812 src_space_id = SpaceId(space_id);
2813 src_space_top = space->top();
2814 const size_t src_region_idx = sd.region(src_cp);
2815 closure.set_source(sd.region_to_addr(src_region_idx));
2816 return src_region_idx;
2817 } else {
2818 assert(src_cp->data_size() == 0, "sanity");
2819 }
2820 }
2821 }
2822 } while (++space_id < last_space_id);
2823
2824 assert(false, "no source region was found");
2825 return 0;
2826 }
2827
2828 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2829 {
2830 typedef ParMarkBitMap::IterationStatus IterationStatus;
2831 ParMarkBitMap* const bitmap = mark_bitmap();
2832 ParallelCompactData& sd = summary_data();
2833 RegionData* const region_ptr = sd.region(region_idx);
2834
2835 // Get the source region and related info.
2836 size_t src_region_idx = region_ptr->source_region();
2837 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2838 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2839 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2840
2841 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2842
2843 // Adjust src_region_idx to prepare for decrementing destination counts (the
2844 // destination count is not decremented when a region is copied to itself).
2845 if (src_region_idx == region_idx) {
2846 src_region_idx += 1;
2847 }
2848
2849 if (bitmap->is_unmarked(closure.source())) {
2850 // The first source word is in the middle of an object; copy the remainder
2851 // of the object or as much as will fit. The fact that pointer updates were
2852 // deferred will be noted when the object header is processed.
2853 HeapWord* const old_src_addr = closure.source();
2854 closure.copy_partial_obj();
2855 if (closure.is_full()) {
2856 decrement_destination_counts(cm, src_space_id, src_region_idx,
2857 closure.source());
2858 closure.complete_region(cm, dest_addr, region_ptr);
2859 return;
2860 }
2861
2862 HeapWord* const end_addr = sd.region_align_down(closure.source());
2863 if (sd.region_align_down(old_src_addr) != end_addr) {
2864 // The partial object was copied from more than one source region.
2865 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2866
2867 // Move to the next source region, possibly switching spaces as well. All
2868 // args except end_addr may be modified.
2869 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2870 end_addr);
2871 }
2872 }
2873
2874 do {
2875 HeapWord* const cur_addr = closure.source();
2876 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2877 src_space_top);
2878 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2879
2880 if (status == ParMarkBitMap::incomplete) {
2881 // The last obj that starts in the source region does not end in the
2882 // region.
2883 assert(closure.source() < end_addr, "sanity");
2884 HeapWord* const obj_beg = closure.source();
2885 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2886 src_space_top);
2887 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2888 if (obj_end < range_end) {
2889 // The end was found; the entire object will fit.
2890 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2891 assert(status != ParMarkBitMap::would_overflow, "sanity");
2892 } else {
2893 // The end was not found; the object will not fit.
2894 assert(range_end < src_space_top, "obj cannot cross space boundary");
2895 status = ParMarkBitMap::would_overflow;
2896 }
2897 }
2898
2899 if (status == ParMarkBitMap::would_overflow) {
2900 // The last object did not fit. Note that interior oop updates were
2901 // deferred, then copy enough of the object to fill the region.
2902 cm->push_deferred_object(closure.destination());
2903 status = closure.copy_until_full(); // copies from closure.source()
2904
2905 decrement_destination_counts(cm, src_space_id, src_region_idx,
2906 closure.source());
2907 closure.complete_region(cm, dest_addr, region_ptr);
2908 return;
2909 }
2910
2911 if (status == ParMarkBitMap::full) {
2912 decrement_destination_counts(cm, src_space_id, src_region_idx,
2913 closure.source());
2914 closure.complete_region(cm, dest_addr, region_ptr);
2915 return;
2916 }
2917
2918 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2919
2920 // Move to the next source region, possibly switching spaces as well. All
2921 // args except end_addr may be modified.
2922 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2923 end_addr);
2924 } while (true);
2925 }
2926
2927 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
2928 {
2929 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
2930 fill_region(cm, cl, region_idx);
2931 }
2932
2933 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
2934 {
2935 // Get a shadow region first
2936 ParallelCompactData& sd = summary_data();
2937 RegionData* const region_ptr = sd.region(region_idx);
2938 size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
2939 // The InvalidShadow return value indicates the corresponding heap region is available,
2940 // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
2941 // MoveAndUpdateShadowClosure to fill the acquired shadow region.
2942 if (shadow_region == ParCompactionManager::InvalidShadow) {
2943 MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
2944 region_ptr->shadow_to_normal();
2945 return fill_region(cm, cl, region_idx);
2946 } else {
2947 MoveAndUpdateShadowClosure cl(mark_bitmap(), cm, region_idx, shadow_region);
2948 return fill_region(cm, cl, region_idx);
2949 }
2950 }
2951
2952 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
2953 {
2954 Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
2955 }
2956
2957 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t ®ion_idx)
2958 {
2959 size_t next = cm->next_shadow_region();
2960 ParallelCompactData& sd = summary_data();
2961 size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
2962 uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2963
2964 while (next < old_new_top) {
2965 if (sd.region(next)->mark_shadow()) {
2966 region_idx = next;
2967 return true;
2968 }
2969 next = cm->move_next_shadow_region_by(active_gc_threads);
2970 }
2971
2972 return false;
2973 }
2974
2975 // The shadow region is an optimization to address region dependencies in full GC. The basic
2976 // idea is making more regions available by temporally storing their live objects in empty
2977 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
2978 // GC threads need not wait destination regions to be available before processing sources.
2979 //
2980 // A typical workflow would be:
2981 // After draining its own stack and failing to steal from others, a GC worker would pick an
2982 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
2983 // the shadow region by copying live objects from source regions of the unavailable one. Once
2984 // the unavailable region becomes available, the data in the shadow region will be copied back.
2985 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
2986 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
2987 {
2988 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2989
2990 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2991 SpaceInfo* const space_info = _space_info + id;
2992 MutableSpace* const space = space_info->space();
2993
2994 const size_t beg_region =
2995 sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
2996 const size_t end_region =
2997 sd.addr_to_region_idx(sd.region_align_down(space->end()));
2998
2999 for (size_t cur = beg_region; cur < end_region; ++cur) {
3000 ParCompactionManager::push_shadow_region(cur);
3001 }
3002 }
3003
3004 size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
3005 for (uint i = 0; i < parallel_gc_threads; i++) {
3006 ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i);
3007 cm->set_next_shadow_region(beg_region + i);
3008 }
3009 }
3010
3011 void PSParallelCompact::fill_blocks(size_t region_idx)
3012 {
3013 // Fill in the block table elements for the specified region. Each block
3014 // table element holds the number of live words in the region that are to the
3015 // left of the first object that starts in the block. Thus only blocks in
3016 // which an object starts need to be filled.
3017 //
3018 // The algorithm scans the section of the bitmap that corresponds to the
3019 // region, keeping a running total of the live words. When an object start is
3020 // found, if it's the first to start in the block that contains it, the
3021 // current total is written to the block table element.
3022 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
3023 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
3024 const size_t RegionSize = ParallelCompactData::RegionSize;
3025
3026 ParallelCompactData& sd = summary_data();
3027 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
3028 if (partial_obj_size >= RegionSize) {
3029 return; // No objects start in this region.
3030 }
3031
3032 // Ensure the first loop iteration decides that the block has changed.
3033 size_t cur_block = sd.block_count();
3034
3035 const ParMarkBitMap* const bitmap = mark_bitmap();
3036
3037 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
3038 assert((size_t)1 << Log2BitsPerBlock ==
3039 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
3040
3041 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
3042 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
3043 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
3044 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
3045 while (beg_bit < range_end) {
3046 const size_t new_block = beg_bit >> Log2BitsPerBlock;
3047 if (new_block != cur_block) {
3048 cur_block = new_block;
3049 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
3050 }
3051
3052 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
3053 if (end_bit < range_end - 1) {
3054 live_bits += end_bit - beg_bit + 1;
3055 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
3056 } else {
3057 return;
3058 }
3059 }
3060 }
3061
3062 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3063 {
3064 if (source() != copy_destination()) {
3065 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3066 Copy::aligned_conjoint_words(source(), copy_destination(), words_remaining());
3067 }
3068 update_state(words_remaining());
3069 assert(is_full(), "sanity");
3070 return ParMarkBitMap::full;
3071 }
3072
3073 void MoveAndUpdateClosure::copy_partial_obj()
3074 {
3075 size_t words = words_remaining();
3076
3077 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3078 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3079 if (end_addr < range_end) {
3080 words = bitmap()->obj_size(source(), end_addr);
3081 }
3082
3083 // This test is necessary; if omitted, the pointer updates to a partial object
3084 // that crosses the dense prefix boundary could be overwritten.
3085 if (source() != copy_destination()) {
3086 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3087 Copy::aligned_conjoint_words(source(), copy_destination(), words);
3088 }
3089 update_state(words);
3090 }
3091
3092 void MoveAndUpdateClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
3093 PSParallelCompact::RegionData *region_ptr) {
3094 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
3095 region_ptr->set_completed();
3096 }
3097
3098 ParMarkBitMapClosure::IterationStatus
3099 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3100 assert(destination() != NULL, "sanity");
3101 assert(bitmap()->obj_size(addr) == words, "bad size");
3102
3103 _source = addr;
3104 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3105 destination(), "wrong destination");
3106
3107 if (words > words_remaining()) {
3108 return ParMarkBitMap::would_overflow;
3109 }
3110
3111 // The start_array must be updated even if the object is not moving.
3112 if (_start_array != NULL) {
3113 _start_array->allocate_block(destination());
3114 }
3115
3116 if (copy_destination() != source()) {
3117 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3118 Copy::aligned_conjoint_words(source(), copy_destination(), words);
3119 }
3120
3121 oop moved_oop = cast_to_oop(copy_destination());
3122 compaction_manager()->update_contents(moved_oop);
3123 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3124
3125 update_state(words);
3126 assert(copy_destination() == cast_from_oop<HeapWord*>(moved_oop) + moved_oop->size(), "sanity");
3127 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3128 }
3129
3130 void MoveAndUpdateShadowClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
3131 PSParallelCompact::RegionData *region_ptr) {
3132 assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
3133 // Record the shadow region index
3134 region_ptr->set_shadow_region(_shadow);
3135 // Mark the shadow region as filled to indicate the data is ready to be
3136 // copied back
3137 region_ptr->mark_filled();
3138 // Try to copy the content of the shadow region back to its corresponding
3139 // heap region if available; the GC thread that decreases the destination
3140 // count to zero will do the copying otherwise (see
3141 // PSParallelCompact::decrement_destination_counts).
3142 if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
3143 region_ptr->set_completed();
3144 PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
3145 ParCompactionManager::push_shadow_region_mt_safe(_shadow);
3146 }
3147 }
3148
3149 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3150 ParCompactionManager* cm,
3151 PSParallelCompact::SpaceId space_id) :
3152 ParMarkBitMapClosure(mbm, cm),
3153 _space_id(space_id),
3154 _start_array(PSParallelCompact::start_array(space_id))
3155 {
3156 }
3157
3158 // Updates the references in the object to their new values.
3159 ParMarkBitMapClosure::IterationStatus
3160 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3161 do_addr(addr);
3162 return ParMarkBitMap::incomplete;
3163 }
3164
3165 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3166 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3167 _start_array(PSParallelCompact::start_array(space_id))
3168 {
3169 assert(space_id == PSParallelCompact::old_space_id,
3170 "cannot use FillClosure in the young gen");
3171 }
3172
3173 ParMarkBitMapClosure::IterationStatus
3174 FillClosure::do_addr(HeapWord* addr, size_t size) {
3175 CollectedHeap::fill_with_objects(addr, size);
3176 HeapWord* const end = addr + size;
3177 do {
3178 _start_array->allocate_block(addr);
3179 addr += cast_to_oop(addr)->size();
3180 } while (addr < end);
3181 return ParMarkBitMap::incomplete;
3182 }