1 /*
2 * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "aot/aotLoader.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/stringTable.hpp"
30 #include "classfile/symbolTable.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "code/codeCache.hpp"
33 #include "gc/parallel/gcTaskManager.hpp"
34 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
35 #include "gc/parallel/parMarkBitMap.inline.hpp"
36 #include "gc/parallel/pcTasks.hpp"
37 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
38 #include "gc/parallel/psCompactionManager.inline.hpp"
39 #include "gc/parallel/psOldGen.hpp"
40 #include "gc/parallel/psParallelCompact.inline.hpp"
41 #include "gc/parallel/psPromotionManager.inline.hpp"
42 #include "gc/parallel/psScavenge.hpp"
43 #include "gc/parallel/psYoungGen.hpp"
44 #include "gc/shared/gcCause.hpp"
45 #include "gc/shared/gcHeapSummary.hpp"
46 #include "gc/shared/gcId.hpp"
47 #include "gc/shared/gcLocker.hpp"
48 #include "gc/shared/gcTimer.hpp"
49 #include "gc/shared/gcTrace.hpp"
50 #include "gc/shared/gcTraceTime.inline.hpp"
51 #include "gc/shared/isGCActiveMark.hpp"
52 #include "gc/shared/referencePolicy.hpp"
53 #include "gc/shared/referenceProcessor.hpp"
54 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
55 #include "gc/shared/spaceDecorator.hpp"
56 #include "gc/shared/weakProcessor.hpp"
57 #include "logging/log.hpp"
58 #include "memory/iterator.inline.hpp"
59 #include "memory/resourceArea.hpp"
60 #include "oops/access.inline.hpp"
61 #include "oops/instanceClassLoaderKlass.inline.hpp"
62 #include "oops/instanceKlass.inline.hpp"
63 #include "oops/instanceMirrorKlass.inline.hpp"
64 #include "oops/methodData.hpp"
65 #include "oops/objArrayKlass.inline.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.hpp"
68 #include "runtime/handles.inline.hpp"
69 #include "runtime/safepoint.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "services/management.hpp"
72 #include "services/memTracker.hpp"
73 #include "services/memoryService.hpp"
74 #include "utilities/align.hpp"
75 #include "utilities/debug.hpp"
76 #include "utilities/events.hpp"
77 #include "utilities/formatBuffer.hpp"
78 #include "utilities/macros.hpp"
79 #include "utilities/stack.inline.hpp"
80
81 #include <math.h>
82
83 // All sizes are in HeapWords.
84 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
85 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
86 const size_t ParallelCompactData::RegionSizeBytes =
87 RegionSize << LogHeapWordSize;
88 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
89 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
90 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
91
92 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
93 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
94 const size_t ParallelCompactData::BlockSizeBytes =
95 BlockSize << LogHeapWordSize;
96 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
97 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
98 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
99
100 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
101 const size_t ParallelCompactData::Log2BlocksPerRegion =
102 Log2RegionSize - Log2BlockSize;
103
104 const ParallelCompactData::RegionData::region_sz_t
105 ParallelCompactData::RegionData::dc_shift = 27;
106
107 const ParallelCompactData::RegionData::region_sz_t
108 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
109
110 const ParallelCompactData::RegionData::region_sz_t
111 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
112
113 const ParallelCompactData::RegionData::region_sz_t
114 ParallelCompactData::RegionData::los_mask = ~dc_mask;
115
116 const ParallelCompactData::RegionData::region_sz_t
117 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
118
119 const ParallelCompactData::RegionData::region_sz_t
120 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
121
122 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
123
124 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
125 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
126
127 double PSParallelCompact::_dwl_mean;
128 double PSParallelCompact::_dwl_std_dev;
129 double PSParallelCompact::_dwl_first_term;
130 double PSParallelCompact::_dwl_adjustment;
131 #ifdef ASSERT
132 bool PSParallelCompact::_dwl_initialized = false;
133 #endif // #ifdef ASSERT
134
135 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
136 HeapWord* destination)
137 {
138 assert(src_region_idx != 0, "invalid src_region_idx");
139 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
140 assert(destination != NULL, "invalid destination argument");
141
142 _src_region_idx = src_region_idx;
143 _partial_obj_size = partial_obj_size;
144 _destination = destination;
145
146 // These fields may not be updated below, so make sure they're clear.
147 assert(_dest_region_addr == NULL, "should have been cleared");
148 assert(_first_src_addr == NULL, "should have been cleared");
149
150 // Determine the number of destination regions for the partial object.
151 HeapWord* const last_word = destination + partial_obj_size - 1;
152 const ParallelCompactData& sd = PSParallelCompact::summary_data();
153 HeapWord* const beg_region_addr = sd.region_align_down(destination);
154 HeapWord* const end_region_addr = sd.region_align_down(last_word);
155
156 if (beg_region_addr == end_region_addr) {
157 // One destination region.
158 _destination_count = 1;
159 if (end_region_addr == destination) {
160 // The destination falls on a region boundary, thus the first word of the
161 // partial object will be the first word copied to the destination region.
162 _dest_region_addr = end_region_addr;
163 _first_src_addr = sd.region_to_addr(src_region_idx);
164 }
165 } else {
166 // Two destination regions. When copied, the partial object will cross a
167 // destination region boundary, so a word somewhere within the partial
168 // object will be the first word copied to the second destination region.
169 _destination_count = 2;
170 _dest_region_addr = end_region_addr;
171 const size_t ofs = pointer_delta(end_region_addr, destination);
172 assert(ofs < _partial_obj_size, "sanity");
173 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
174 }
175 }
176
177 void SplitInfo::clear()
178 {
179 _src_region_idx = 0;
180 _partial_obj_size = 0;
181 _destination = NULL;
182 _destination_count = 0;
183 _dest_region_addr = NULL;
184 _first_src_addr = NULL;
185 assert(!is_valid(), "sanity");
186 }
187
188 #ifdef ASSERT
189 void SplitInfo::verify_clear()
190 {
191 assert(_src_region_idx == 0, "not clear");
192 assert(_partial_obj_size == 0, "not clear");
193 assert(_destination == NULL, "not clear");
194 assert(_destination_count == 0, "not clear");
195 assert(_dest_region_addr == NULL, "not clear");
196 assert(_first_src_addr == NULL, "not clear");
197 }
198 #endif // #ifdef ASSERT
199
200
201 void PSParallelCompact::print_on_error(outputStream* st) {
202 _mark_bitmap.print_on_error(st);
203 }
204
205 #ifndef PRODUCT
206 const char* PSParallelCompact::space_names[] = {
207 "old ", "eden", "from", "to "
208 };
209
210 void PSParallelCompact::print_region_ranges() {
211 if (!log_develop_is_enabled(Trace, gc, compaction)) {
212 return;
213 }
214 Log(gc, compaction) log;
215 ResourceMark rm;
216 LogStream ls(log.trace());
217 Universe::print_on(&ls);
218 log.trace("space bottom top end new_top");
219 log.trace("------ ---------- ---------- ---------- ----------");
220
221 for (unsigned int id = 0; id < last_space_id; ++id) {
222 const MutableSpace* space = _space_info[id].space();
223 log.trace("%u %s "
224 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
225 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
226 id, space_names[id],
227 summary_data().addr_to_region_idx(space->bottom()),
228 summary_data().addr_to_region_idx(space->top()),
229 summary_data().addr_to_region_idx(space->end()),
230 summary_data().addr_to_region_idx(_space_info[id].new_top()));
231 }
232 }
233
234 void
235 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
236 {
237 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
238 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
239
240 ParallelCompactData& sd = PSParallelCompact::summary_data();
241 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
242 log_develop_trace(gc, compaction)(
243 REGION_IDX_FORMAT " " PTR_FORMAT " "
244 REGION_IDX_FORMAT " " PTR_FORMAT " "
245 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
246 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
247 i, p2i(c->data_location()), dci, p2i(c->destination()),
248 c->partial_obj_size(), c->live_obj_size(),
249 c->data_size(), c->source_region(), c->destination_count());
250
251 #undef REGION_IDX_FORMAT
252 #undef REGION_DATA_FORMAT
253 }
254
255 void
256 print_generic_summary_data(ParallelCompactData& summary_data,
257 HeapWord* const beg_addr,
258 HeapWord* const end_addr)
259 {
260 size_t total_words = 0;
261 size_t i = summary_data.addr_to_region_idx(beg_addr);
262 const size_t last = summary_data.addr_to_region_idx(end_addr);
263 HeapWord* pdest = 0;
264
265 while (i < last) {
266 ParallelCompactData::RegionData* c = summary_data.region(i);
267 if (c->data_size() != 0 || c->destination() != pdest) {
268 print_generic_summary_region(i, c);
269 total_words += c->data_size();
270 pdest = c->destination();
271 }
272 ++i;
273 }
274
275 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
276 }
277
278 void
279 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
280 HeapWord* const beg_addr,
281 HeapWord* const end_addr) {
282 ::print_generic_summary_data(summary_data,beg_addr, end_addr);
283 }
284
285 void
286 print_generic_summary_data(ParallelCompactData& summary_data,
287 SpaceInfo* space_info)
288 {
289 if (!log_develop_is_enabled(Trace, gc, compaction)) {
290 return;
291 }
292
293 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
294 const MutableSpace* space = space_info[id].space();
295 print_generic_summary_data(summary_data, space->bottom(),
296 MAX2(space->top(), space_info[id].new_top()));
297 }
298 }
299
300 void
301 print_initial_summary_data(ParallelCompactData& summary_data,
302 const MutableSpace* space) {
303 if (space->top() == space->bottom()) {
304 return;
305 }
306
307 const size_t region_size = ParallelCompactData::RegionSize;
308 typedef ParallelCompactData::RegionData RegionData;
309 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
310 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
311 const RegionData* c = summary_data.region(end_region - 1);
312 HeapWord* end_addr = c->destination() + c->data_size();
313 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
314
315 // Print (and count) the full regions at the beginning of the space.
316 size_t full_region_count = 0;
317 size_t i = summary_data.addr_to_region_idx(space->bottom());
318 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
319 ParallelCompactData::RegionData* c = summary_data.region(i);
320 log_develop_trace(gc, compaction)(
321 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
322 i, p2i(c->destination()),
323 c->partial_obj_size(), c->live_obj_size(),
324 c->data_size(), c->source_region(), c->destination_count());
325 ++full_region_count;
326 ++i;
327 }
328
329 size_t live_to_right = live_in_space - full_region_count * region_size;
330
331 double max_reclaimed_ratio = 0.0;
332 size_t max_reclaimed_ratio_region = 0;
333 size_t max_dead_to_right = 0;
334 size_t max_live_to_right = 0;
335
336 // Print the 'reclaimed ratio' for regions while there is something live in
337 // the region or to the right of it. The remaining regions are empty (and
338 // uninteresting), and computing the ratio will result in division by 0.
339 while (i < end_region && live_to_right > 0) {
340 c = summary_data.region(i);
341 HeapWord* const region_addr = summary_data.region_to_addr(i);
342 const size_t used_to_right = pointer_delta(space->top(), region_addr);
343 const size_t dead_to_right = used_to_right - live_to_right;
344 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
345
346 if (reclaimed_ratio > max_reclaimed_ratio) {
347 max_reclaimed_ratio = reclaimed_ratio;
348 max_reclaimed_ratio_region = i;
349 max_dead_to_right = dead_to_right;
350 max_live_to_right = live_to_right;
351 }
352
353 ParallelCompactData::RegionData* c = summary_data.region(i);
354 log_develop_trace(gc, compaction)(
355 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
356 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
357 i, p2i(c->destination()),
358 c->partial_obj_size(), c->live_obj_size(),
359 c->data_size(), c->source_region(), c->destination_count(),
360 reclaimed_ratio, dead_to_right, live_to_right);
361
362
363 live_to_right -= c->data_size();
364 ++i;
365 }
366
367 // Any remaining regions are empty. Print one more if there is one.
368 if (i < end_region) {
369 ParallelCompactData::RegionData* c = summary_data.region(i);
370 log_develop_trace(gc, compaction)(
371 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
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 }
376
377 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
378 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
379 }
380
381 void
382 print_initial_summary_data(ParallelCompactData& summary_data,
383 SpaceInfo* space_info) {
384 if (!log_develop_is_enabled(Trace, gc, compaction)) {
385 return;
386 }
387
388 unsigned int id = PSParallelCompact::old_space_id;
389 const MutableSpace* space;
390 do {
391 space = space_info[id].space();
392 print_initial_summary_data(summary_data, space);
393 } while (++id < PSParallelCompact::eden_space_id);
394
395 do {
396 space = space_info[id].space();
397 print_generic_summary_data(summary_data, space->bottom(), space->top());
398 } while (++id < PSParallelCompact::last_space_id);
399 }
400 #endif // #ifndef PRODUCT
401
402 #ifdef ASSERT
403 size_t add_obj_count;
404 size_t add_obj_size;
405 size_t mark_bitmap_count;
406 size_t mark_bitmap_size;
407 #endif // #ifdef ASSERT
408
409 ParallelCompactData::ParallelCompactData() :
410 _region_start(NULL),
411 DEBUG_ONLY(_region_end(NULL) COMMA)
412 _region_vspace(NULL),
413 _reserved_byte_size(0),
414 _region_data(NULL),
415 _region_count(0),
416 _block_vspace(NULL),
417 _block_data(NULL),
418 _block_count(0) {}
419
420 bool ParallelCompactData::initialize(MemRegion covered_region)
421 {
422 _region_start = covered_region.start();
423 const size_t region_size = covered_region.word_size();
424 DEBUG_ONLY(_region_end = _region_start + region_size;)
425
426 assert(region_align_down(_region_start) == _region_start,
427 "region start not aligned");
428 assert((region_size & RegionSizeOffsetMask) == 0,
429 "region size not a multiple of RegionSize");
430
431 bool result = initialize_region_data(region_size) && initialize_block_data();
432 return result;
433 }
434
435 PSVirtualSpace*
436 ParallelCompactData::create_vspace(size_t count, size_t element_size)
437 {
438 const size_t raw_bytes = count * element_size;
439 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
440 const size_t granularity = os::vm_allocation_granularity();
441 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
442
443 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
444 MAX2(page_sz, granularity);
445 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
446 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
447 rs.size());
448
449 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
450
451 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
452 if (vspace != 0) {
453 if (vspace->expand_by(_reserved_byte_size)) {
454 return vspace;
455 }
456 delete vspace;
457 // Release memory reserved in the space.
458 rs.release();
459 }
460
461 return 0;
462 }
463
464 bool ParallelCompactData::initialize_region_data(size_t region_size)
465 {
466 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
467 _region_vspace = create_vspace(count, sizeof(RegionData));
468 if (_region_vspace != 0) {
469 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
470 _region_count = count;
471 return true;
472 }
473 return false;
474 }
475
476 bool ParallelCompactData::initialize_block_data()
477 {
478 assert(_region_count != 0, "region data must be initialized first");
479 const size_t count = _region_count << Log2BlocksPerRegion;
480 _block_vspace = create_vspace(count, sizeof(BlockData));
481 if (_block_vspace != 0) {
482 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
483 _block_count = count;
484 return true;
485 }
486 return false;
487 }
488
489 void ParallelCompactData::clear()
490 {
491 memset(_region_data, 0, _region_vspace->committed_size());
492 memset(_block_data, 0, _block_vspace->committed_size());
493 }
494
495 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
496 assert(beg_region <= _region_count, "beg_region out of range");
497 assert(end_region <= _region_count, "end_region out of range");
498 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
499
500 const size_t region_cnt = end_region - beg_region;
501 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
502
503 const size_t beg_block = beg_region * BlocksPerRegion;
504 const size_t block_cnt = region_cnt * BlocksPerRegion;
505 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
506 }
507
508 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
509 {
510 const RegionData* cur_cp = region(region_idx);
511 const RegionData* const end_cp = region(region_count() - 1);
512
513 HeapWord* result = region_to_addr(region_idx);
514 if (cur_cp < end_cp) {
515 do {
516 result += cur_cp->partial_obj_size();
517 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
518 }
519 return result;
520 }
521
522 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
523 {
524 const size_t obj_ofs = pointer_delta(addr, _region_start);
525 const size_t beg_region = obj_ofs >> Log2RegionSize;
526 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
527
528 DEBUG_ONLY(Atomic::inc(&add_obj_count);)
529 DEBUG_ONLY(Atomic::add(len, &add_obj_size);)
530
531 if (beg_region == end_region) {
532 // All in one region.
533 _region_data[beg_region].add_live_obj(len);
534 return;
535 }
536
537 // First region.
538 const size_t beg_ofs = region_offset(addr);
539 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
540
541 Klass* klass = ((oop)addr)->klass();
542 // Middle regions--completely spanned by this object.
543 for (size_t region = beg_region + 1; region < end_region; ++region) {
544 _region_data[region].set_partial_obj_size(RegionSize);
545 _region_data[region].set_partial_obj_addr(addr);
546 }
547
548 // Last region.
549 const size_t end_ofs = region_offset(addr + len - 1);
550 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
551 _region_data[end_region].set_partial_obj_addr(addr);
552 }
553
554 void
555 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
556 {
557 assert(region_offset(beg) == 0, "not RegionSize aligned");
558 assert(region_offset(end) == 0, "not RegionSize aligned");
559
560 size_t cur_region = addr_to_region_idx(beg);
561 const size_t end_region = addr_to_region_idx(end);
562 HeapWord* addr = beg;
563 while (cur_region < end_region) {
564 _region_data[cur_region].set_destination(addr);
565 _region_data[cur_region].set_destination_count(0);
566 _region_data[cur_region].set_source_region(cur_region);
567 _region_data[cur_region].set_data_location(addr);
568
569 // Update live_obj_size so the region appears completely full.
570 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
571 _region_data[cur_region].set_live_obj_size(live_size);
572
573 ++cur_region;
574 addr += RegionSize;
575 }
576 }
577
578 // Find the point at which a space can be split and, if necessary, record the
579 // split point.
580 //
581 // If the current src region (which overflowed the destination space) doesn't
582 // have a partial object, the split point is at the beginning of the current src
583 // region (an "easy" split, no extra bookkeeping required).
584 //
585 // If the current src region has a partial object, the split point is in the
586 // region where that partial object starts (call it the split_region). If
587 // split_region has a partial object, then the split point is just after that
588 // partial object (a "hard" split where we have to record the split data and
589 // zero the partial_obj_size field). With a "hard" split, we know that the
590 // partial_obj ends within split_region because the partial object that caused
591 // the overflow starts in split_region. If split_region doesn't have a partial
592 // obj, then the split is at the beginning of split_region (another "easy"
593 // split).
594 HeapWord*
595 ParallelCompactData::summarize_split_space(size_t src_region,
596 SplitInfo& split_info,
597 HeapWord* destination,
598 HeapWord* target_end,
599 HeapWord** target_next)
600 {
601 assert(destination <= target_end, "sanity");
602 assert(destination + _region_data[src_region].data_size() > target_end,
603 "region should not fit into target space");
604 assert(is_region_aligned(target_end), "sanity");
605
606 size_t split_region = src_region;
607 HeapWord* split_destination = destination;
608 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
609
610 if (destination + partial_obj_size > target_end) {
611 // The split point is just after the partial object (if any) in the
612 // src_region that contains the start of the object that overflowed the
613 // destination space.
614 //
615 // Find the start of the "overflow" object and set split_region to the
616 // region containing it.
617 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
618 split_region = addr_to_region_idx(overflow_obj);
619
620 // Clear the source_region field of all destination regions whose first word
621 // came from data after the split point (a non-null source_region field
622 // implies a region must be filled).
623 //
624 // An alternative to the simple loop below: clear during post_compact(),
625 // which uses memcpy instead of individual stores, and is easy to
626 // parallelize. (The downside is that it clears the entire RegionData
627 // object as opposed to just one field.)
628 //
629 // post_compact() would have to clear the summary data up to the highest
630 // address that was written during the summary phase, which would be
631 //
632 // max(top, max(new_top, clear_top))
633 //
634 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
635 // to target_end.
636 const RegionData* const sr = region(split_region);
637 const size_t beg_idx =
638 addr_to_region_idx(region_align_up(sr->destination() +
639 sr->partial_obj_size()));
640 const size_t end_idx = addr_to_region_idx(target_end);
641
642 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
643 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
644 _region_data[idx].set_source_region(0);
645 }
646
647 // Set split_destination and partial_obj_size to reflect the split region.
648 split_destination = sr->destination();
649 partial_obj_size = sr->partial_obj_size();
650 }
651
652 // The split is recorded only if a partial object extends onto the region.
653 if (partial_obj_size != 0) {
654 _region_data[split_region].set_partial_obj_size(0);
655 split_info.record(split_region, partial_obj_size, split_destination);
656 }
657
658 // Setup the continuation addresses.
659 *target_next = split_destination + partial_obj_size;
660 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
661
662 if (log_develop_is_enabled(Trace, gc, compaction)) {
663 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
664 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
665 split_type, p2i(source_next), split_region, partial_obj_size);
666 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
667 split_type, p2i(split_destination),
668 addr_to_region_idx(split_destination),
669 p2i(*target_next));
670
671 if (partial_obj_size != 0) {
672 HeapWord* const po_beg = split_info.destination();
673 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
674 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
675 split_type,
676 p2i(po_beg), addr_to_region_idx(po_beg),
677 p2i(po_end), addr_to_region_idx(po_end));
678 }
679 }
680
681 return source_next;
682 }
683
684 bool ParallelCompactData::summarize(SplitInfo& split_info,
685 HeapWord* source_beg, HeapWord* source_end,
686 HeapWord** source_next,
687 HeapWord* target_beg, HeapWord* target_end,
688 HeapWord** target_next)
689 {
690 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
691 log_develop_trace(gc, compaction)(
692 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
693 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
694 p2i(source_beg), p2i(source_end), p2i(source_next_val),
695 p2i(target_beg), p2i(target_end), p2i(*target_next));
696
697 size_t cur_region = addr_to_region_idx(source_beg);
698 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
699
700 HeapWord *dest_addr = target_beg;
701 while (cur_region < end_region) {
702 // The destination must be set even if the region has no data.
703 _region_data[cur_region].set_destination(dest_addr);
704
705 size_t words = _region_data[cur_region].data_size();
706 if (words > 0) {
707 // If cur_region does not fit entirely into the target space, find a point
708 // at which the source space can be 'split' so that part is copied to the
709 // target space and the rest is copied elsewhere.
710 if (dest_addr + words > target_end) {
711 assert(source_next != NULL, "source_next is NULL when splitting");
712 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
713 target_end, target_next);
714 return false;
715 }
716
717 // Compute the destination_count for cur_region, and if necessary, update
718 // source_region for a destination region. The source_region field is
719 // updated if cur_region is the first (left-most) region to be copied to a
720 // destination region.
721 //
722 // The destination_count calculation is a bit subtle. A region that has
723 // data that compacts into itself does not count itself as a destination.
724 // This maintains the invariant that a zero count means the region is
725 // available and can be claimed and then filled.
726 uint destination_count = 0;
727 if (split_info.is_split(cur_region)) {
728 // The current region has been split: the partial object will be copied
729 // to one destination space and the remaining data will be copied to
730 // another destination space. Adjust the initial destination_count and,
731 // if necessary, set the source_region field if the partial object will
732 // cross a destination region boundary.
733 destination_count = split_info.destination_count();
734 if (destination_count == 2) {
735 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
736 _region_data[dest_idx].set_source_region(cur_region);
737 }
738 }
739
740 HeapWord* const last_addr = dest_addr + words - 1;
741 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
742 const size_t dest_region_2 = addr_to_region_idx(last_addr);
743
744 // Initially assume that the destination regions will be the same and
745 // adjust the value below if necessary. Under this assumption, if
746 // cur_region == dest_region_2, then cur_region will be compacted
747 // completely into itself.
748 destination_count += cur_region == dest_region_2 ? 0 : 1;
749 if (dest_region_1 != dest_region_2) {
750 // Destination regions differ; adjust destination_count.
751 destination_count += 1;
752 // Data from cur_region will be copied to the start of dest_region_2.
753 _region_data[dest_region_2].set_source_region(cur_region);
754 } else if (region_offset(dest_addr) == 0) {
755 // Data from cur_region will be copied to the start of the destination
756 // region.
757 _region_data[dest_region_1].set_source_region(cur_region);
758 }
759
760 _region_data[cur_region].set_destination_count(destination_count);
761 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
762 dest_addr += words;
763 }
764
765 ++cur_region;
766 }
767
768 *target_next = dest_addr;
769 return true;
770 }
771
772 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
773 assert(addr != NULL, "Should detect NULL oop earlier");
774 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
775 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
776
777 // Region covering the object.
778 RegionData* const region_ptr = addr_to_region_ptr(addr);
779 HeapWord* result = region_ptr->destination();
780
781 // If the entire Region is live, the new location is region->destination + the
782 // offset of the object within in the Region.
783
784 // Run some performance tests to determine if this special case pays off. It
785 // is worth it for pointers into the dense prefix. If the optimization to
786 // avoid pointer updates in regions that only point to the dense prefix is
787 // ever implemented, this should be revisited.
788 if (region_ptr->data_size() == RegionSize) {
789 result += region_offset(addr);
790 return result;
791 }
792
793 // Otherwise, the new location is region->destination + block offset + the
794 // number of live words in the Block that are (a) to the left of addr and (b)
795 // due to objects that start in the Block.
796
797 // Fill in the block table if necessary. This is unsynchronized, so multiple
798 // threads may fill the block table for a region (harmless, since it is
799 // idempotent).
800 if (!region_ptr->blocks_filled()) {
801 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
802 region_ptr->set_blocks_filled();
803 }
804
805 HeapWord* const search_start = block_align_down(addr);
806 const size_t block_offset = addr_to_block_ptr(addr)->offset();
807
808 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
809 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
810 result += block_offset + live;
811 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
812 return result;
813 }
814
815 #ifdef ASSERT
816 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
817 {
818 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
819 const size_t* const end = (const size_t*)vspace->committed_high_addr();
820 for (const size_t* p = beg; p < end; ++p) {
821 assert(*p == 0, "not zero");
822 }
823 }
824
825 void ParallelCompactData::verify_clear()
826 {
827 verify_clear(_region_vspace);
828 verify_clear(_block_vspace);
829 }
830 #endif // #ifdef ASSERT
831
832 STWGCTimer PSParallelCompact::_gc_timer;
833 ParallelOldTracer PSParallelCompact::_gc_tracer;
834 elapsedTimer PSParallelCompact::_accumulated_time;
835 unsigned int PSParallelCompact::_total_invocations = 0;
836 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
837 jlong PSParallelCompact::_time_of_last_gc = 0;
838 CollectorCounters* PSParallelCompact::_counters = NULL;
839 ParMarkBitMap PSParallelCompact::_mark_bitmap;
840 ParallelCompactData PSParallelCompact::_summary_data;
841
842 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
843
844 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
845
846 class PCReferenceProcessor: public ReferenceProcessor {
847 public:
848 PCReferenceProcessor(
849 BoolObjectClosure* is_subject_to_discovery,
850 BoolObjectClosure* is_alive_non_header) :
851 ReferenceProcessor(is_subject_to_discovery,
852 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
853 ParallelGCThreads, // mt processing degree
854 true, // mt discovery
855 ParallelGCThreads, // mt discovery degree
856 true, // atomic_discovery
857 is_alive_non_header) {
858 }
859
860 template<typename T> bool discover(oop obj, ReferenceType type) {
861 T* referent_addr = (T*) java_lang_ref_Reference::referent_addr_raw(obj);
862 T heap_oop = RawAccess<>::oop_load(referent_addr);
863 oop referent = CompressedOops::decode_not_null(heap_oop);
864 return PSParallelCompact::mark_bitmap()->is_unmarked(referent)
865 && ReferenceProcessor::discover_reference(obj, type);
866 }
867 virtual bool discover_reference(oop obj, ReferenceType type) {
868 if (UseCompressedOops) {
869 return discover<narrowOop>(obj, type);
870 } else {
871 return discover<oop>(obj, type);
872 }
873 }
874 };
875
876 void PSParallelCompact::post_initialize() {
877 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
878 _span_based_discoverer.set_span(heap->reserved_region());
879 _ref_processor =
880 new PCReferenceProcessor(&_span_based_discoverer,
881 &_is_alive_closure); // non-header is alive closure
882
883 _counters = new CollectorCounters("Parallel full collection pauses", 1);
884
885 // Initialize static fields in ParCompactionManager.
886 ParCompactionManager::initialize(mark_bitmap());
887 }
888
889 bool PSParallelCompact::initialize() {
890 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
891 MemRegion mr = heap->reserved_region();
892
893 // Was the old gen get allocated successfully?
894 if (!heap->old_gen()->is_allocated()) {
895 return false;
896 }
897
898 initialize_space_info();
899 initialize_dead_wood_limiter();
900
901 if (!_mark_bitmap.initialize(mr)) {
902 vm_shutdown_during_initialization(
903 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
904 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
905 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
906 return false;
907 }
908
909 if (!_summary_data.initialize(mr)) {
910 vm_shutdown_during_initialization(
911 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
912 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
913 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
914 return false;
915 }
916
917 return true;
918 }
919
920 void PSParallelCompact::initialize_space_info()
921 {
922 memset(&_space_info, 0, sizeof(_space_info));
923
924 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
925 PSYoungGen* young_gen = heap->young_gen();
926
927 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
928 _space_info[eden_space_id].set_space(young_gen->eden_space());
929 _space_info[from_space_id].set_space(young_gen->from_space());
930 _space_info[to_space_id].set_space(young_gen->to_space());
931
932 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
933 }
934
935 void PSParallelCompact::initialize_dead_wood_limiter()
936 {
937 const size_t max = 100;
938 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
939 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
940 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
941 DEBUG_ONLY(_dwl_initialized = true;)
942 _dwl_adjustment = normal_distribution(1.0);
943 }
944
945 void
946 PSParallelCompact::clear_data_covering_space(SpaceId id)
947 {
948 // At this point, top is the value before GC, new_top() is the value that will
949 // be set at the end of GC. The marking bitmap is cleared to top; nothing
950 // should be marked above top. The summary data is cleared to the larger of
951 // top & new_top.
952 MutableSpace* const space = _space_info[id].space();
953 HeapWord* const bot = space->bottom();
954 HeapWord* const top = space->top();
955 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
956
957 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
958 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
959 _mark_bitmap.clear_range(beg_bit, end_bit);
960
961 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
962 const size_t end_region =
963 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
964 _summary_data.clear_range(beg_region, end_region);
965
966 // Clear the data used to 'split' regions.
967 SplitInfo& split_info = _space_info[id].split_info();
968 if (split_info.is_valid()) {
969 split_info.clear();
970 }
971 DEBUG_ONLY(split_info.verify_clear();)
972 }
973
974 void PSParallelCompact::pre_compact()
975 {
976 // Update the from & to space pointers in space_info, since they are swapped
977 // at each young gen gc. Do the update unconditionally (even though a
978 // promotion failure does not swap spaces) because an unknown number of young
979 // collections will have swapped the spaces an unknown number of times.
980 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
981 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
982 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
983 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
984
985 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
986 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
987
988 // Increment the invocation count
989 heap->increment_total_collections(true);
990
991 // We need to track unique mark sweep invocations as well.
992 _total_invocations++;
993
994 heap->print_heap_before_gc();
995 heap->trace_heap_before_gc(&_gc_tracer);
996
997 // Fill in TLABs
998 heap->ensure_parsability(true); // retire TLABs
999
1000 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
1001 HandleMark hm; // Discard invalid handles created during verification
1002 Universe::verify("Before GC");
1003 }
1004
1005 // Verify object start arrays
1006 if (VerifyObjectStartArray &&
1007 VerifyBeforeGC) {
1008 heap->old_gen()->verify_object_start_array();
1009 }
1010
1011 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1012 DEBUG_ONLY(summary_data().verify_clear();)
1013
1014 // Have worker threads release resources the next time they run a task.
1015 gc_task_manager()->release_all_resources();
1016
1017 ParCompactionManager::reset_all_bitmap_query_caches();
1018 }
1019
1020 void PSParallelCompact::post_compact()
1021 {
1022 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1023
1024 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1025 // Clear the marking bitmap, summary data and split info.
1026 clear_data_covering_space(SpaceId(id));
1027 // Update top(). Must be done after clearing the bitmap and summary data.
1028 _space_info[id].publish_new_top();
1029 }
1030
1031 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1032 MutableSpace* const from_space = _space_info[from_space_id].space();
1033 MutableSpace* const to_space = _space_info[to_space_id].space();
1034
1035 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1036 bool eden_empty = eden_space->is_empty();
1037 if (!eden_empty) {
1038 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1039 heap->young_gen(), heap->old_gen());
1040 }
1041
1042 // Update heap occupancy information which is used as input to the soft ref
1043 // clearing policy at the next gc.
1044 Universe::update_heap_info_at_gc();
1045
1046 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1047 to_space->is_empty();
1048
1049 PSCardTable* ct = heap->card_table();
1050 MemRegion old_mr = heap->old_gen()->reserved();
1051 if (young_gen_empty) {
1052 ct->clear(MemRegion(old_mr.start(), old_mr.end()));
1053 } else {
1054 ct->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1055 }
1056
1057 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1058 ClassLoaderDataGraph::purge();
1059 MetaspaceUtils::verify_metrics();
1060
1061 heap->prune_scavengable_nmethods();
1062 JvmtiExport::gc_epilogue();
1063
1064 #if COMPILER2_OR_JVMCI
1065 DerivedPointerTable::update_pointers();
1066 #endif
1067
1068 if (ZapUnusedHeapArea) {
1069 heap->gen_mangle_unused_area();
1070 }
1071
1072 // Update time of last GC
1073 reset_millis_since_last_gc();
1074 }
1075
1076 HeapWord*
1077 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1078 bool maximum_compaction)
1079 {
1080 const size_t region_size = ParallelCompactData::RegionSize;
1081 const ParallelCompactData& sd = summary_data();
1082
1083 const MutableSpace* const space = _space_info[id].space();
1084 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1085 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1086 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1087
1088 // Skip full regions at the beginning of the space--they are necessarily part
1089 // of the dense prefix.
1090 size_t full_count = 0;
1091 const RegionData* cp;
1092 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1093 ++full_count;
1094 }
1095
1096 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1097 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1098 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1099 if (maximum_compaction || cp == end_cp || interval_ended) {
1100 _maximum_compaction_gc_num = total_invocations();
1101 return sd.region_to_addr(cp);
1102 }
1103
1104 HeapWord* const new_top = _space_info[id].new_top();
1105 const size_t space_live = pointer_delta(new_top, space->bottom());
1106 const size_t space_used = space->used_in_words();
1107 const size_t space_capacity = space->capacity_in_words();
1108
1109 const double cur_density = double(space_live) / space_capacity;
1110 const double deadwood_density =
1111 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1112 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1113
1114 if (TraceParallelOldGCDensePrefix) {
1115 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1116 cur_density, deadwood_density, deadwood_goal);
1117 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1118 "space_cap=" SIZE_FORMAT,
1119 space_live, space_used,
1120 space_capacity);
1121 }
1122
1123 // XXX - Use binary search?
1124 HeapWord* dense_prefix = sd.region_to_addr(cp);
1125 const RegionData* full_cp = cp;
1126 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1127 while (cp < end_cp) {
1128 HeapWord* region_destination = cp->destination();
1129 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1130 if (TraceParallelOldGCDensePrefix && Verbose) {
1131 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1132 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1133 sd.region(cp), p2i(region_destination),
1134 p2i(dense_prefix), cur_deadwood);
1135 }
1136
1137 if (cur_deadwood >= deadwood_goal) {
1138 // Found the region that has the correct amount of deadwood to the left.
1139 // This typically occurs after crossing a fairly sparse set of regions, so
1140 // iterate backwards over those sparse regions, looking for the region
1141 // that has the lowest density of live objects 'to the right.'
1142 size_t space_to_left = sd.region(cp) * region_size;
1143 size_t live_to_left = space_to_left - cur_deadwood;
1144 size_t space_to_right = space_capacity - space_to_left;
1145 size_t live_to_right = space_live - live_to_left;
1146 double density_to_right = double(live_to_right) / space_to_right;
1147 while (cp > full_cp) {
1148 --cp;
1149 const size_t prev_region_live_to_right = live_to_right -
1150 cp->data_size();
1151 const size_t prev_region_space_to_right = space_to_right + region_size;
1152 double prev_region_density_to_right =
1153 double(prev_region_live_to_right) / prev_region_space_to_right;
1154 if (density_to_right <= prev_region_density_to_right) {
1155 return dense_prefix;
1156 }
1157 if (TraceParallelOldGCDensePrefix && Verbose) {
1158 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1159 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1160 prev_region_density_to_right);
1161 }
1162 dense_prefix -= region_size;
1163 live_to_right = prev_region_live_to_right;
1164 space_to_right = prev_region_space_to_right;
1165 density_to_right = prev_region_density_to_right;
1166 }
1167 return dense_prefix;
1168 }
1169
1170 dense_prefix += region_size;
1171 ++cp;
1172 }
1173
1174 return dense_prefix;
1175 }
1176
1177 #ifndef PRODUCT
1178 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1179 const SpaceId id,
1180 const bool maximum_compaction,
1181 HeapWord* const addr)
1182 {
1183 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1184 RegionData* const cp = summary_data().region(region_idx);
1185 const MutableSpace* const space = _space_info[id].space();
1186 HeapWord* const new_top = _space_info[id].new_top();
1187
1188 const size_t space_live = pointer_delta(new_top, space->bottom());
1189 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1190 const size_t space_cap = space->capacity_in_words();
1191 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1192 const size_t live_to_right = new_top - cp->destination();
1193 const size_t dead_to_right = space->top() - addr - live_to_right;
1194
1195 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1196 "spl=" SIZE_FORMAT " "
1197 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1198 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1199 " ratio=%10.8f",
1200 algorithm, p2i(addr), region_idx,
1201 space_live,
1202 dead_to_left, dead_to_left_pct,
1203 dead_to_right, live_to_right,
1204 double(dead_to_right) / live_to_right);
1205 }
1206 #endif // #ifndef PRODUCT
1207
1208 // Return a fraction indicating how much of the generation can be treated as
1209 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1210 // based on the density of live objects in the generation to determine a limit,
1211 // which is then adjusted so the return value is min_percent when the density is
1212 // 1.
1213 //
1214 // The following table shows some return values for a different values of the
1215 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1216 // min_percent is 1.
1217 //
1218 // fraction allowed as dead wood
1219 // -----------------------------------------------------------------
1220 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1221 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1222 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1223 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1224 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1225 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1226 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1227 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1228 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1229 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1230 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1231 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1232 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1233 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1234 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1235 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1236 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1237 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1238 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1239 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1240 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1241 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1242 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1243
1244 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1245 {
1246 assert(_dwl_initialized, "uninitialized");
1247
1248 // The raw limit is the value of the normal distribution at x = density.
1249 const double raw_limit = normal_distribution(density);
1250
1251 // Adjust the raw limit so it becomes the minimum when the density is 1.
1252 //
1253 // First subtract the adjustment value (which is simply the precomputed value
1254 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1255 // Then add the minimum value, so the minimum is returned when the density is
1256 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1257 const double min = double(min_percent) / 100.0;
1258 const double limit = raw_limit - _dwl_adjustment + min;
1259 return MAX2(limit, 0.0);
1260 }
1261
1262 ParallelCompactData::RegionData*
1263 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1264 const RegionData* end)
1265 {
1266 const size_t region_size = ParallelCompactData::RegionSize;
1267 ParallelCompactData& sd = summary_data();
1268 size_t left = sd.region(beg);
1269 size_t right = end > beg ? sd.region(end) - 1 : left;
1270
1271 // Binary search.
1272 while (left < right) {
1273 // Equivalent to (left + right) / 2, but does not overflow.
1274 const size_t middle = left + (right - left) / 2;
1275 RegionData* const middle_ptr = sd.region(middle);
1276 HeapWord* const dest = middle_ptr->destination();
1277 HeapWord* const addr = sd.region_to_addr(middle);
1278 assert(dest != NULL, "sanity");
1279 assert(dest <= addr, "must move left");
1280
1281 if (middle > left && dest < addr) {
1282 right = middle - 1;
1283 } else if (middle < right && middle_ptr->data_size() == region_size) {
1284 left = middle + 1;
1285 } else {
1286 return middle_ptr;
1287 }
1288 }
1289 return sd.region(left);
1290 }
1291
1292 ParallelCompactData::RegionData*
1293 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1294 const RegionData* end,
1295 size_t dead_words)
1296 {
1297 ParallelCompactData& sd = summary_data();
1298 size_t left = sd.region(beg);
1299 size_t right = end > beg ? sd.region(end) - 1 : left;
1300
1301 // Binary search.
1302 while (left < right) {
1303 // Equivalent to (left + right) / 2, but does not overflow.
1304 const size_t middle = left + (right - left) / 2;
1305 RegionData* const middle_ptr = sd.region(middle);
1306 HeapWord* const dest = middle_ptr->destination();
1307 HeapWord* const addr = sd.region_to_addr(middle);
1308 assert(dest != NULL, "sanity");
1309 assert(dest <= addr, "must move left");
1310
1311 const size_t dead_to_left = pointer_delta(addr, dest);
1312 if (middle > left && dead_to_left > dead_words) {
1313 right = middle - 1;
1314 } else if (middle < right && dead_to_left < dead_words) {
1315 left = middle + 1;
1316 } else {
1317 return middle_ptr;
1318 }
1319 }
1320 return sd.region(left);
1321 }
1322
1323 // The result is valid during the summary phase, after the initial summarization
1324 // of each space into itself, and before final summarization.
1325 inline double
1326 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1327 HeapWord* const bottom,
1328 HeapWord* const top,
1329 HeapWord* const new_top)
1330 {
1331 ParallelCompactData& sd = summary_data();
1332
1333 assert(cp != NULL, "sanity");
1334 assert(bottom != NULL, "sanity");
1335 assert(top != NULL, "sanity");
1336 assert(new_top != NULL, "sanity");
1337 assert(top >= new_top, "summary data problem?");
1338 assert(new_top > bottom, "space is empty; should not be here");
1339 assert(new_top >= cp->destination(), "sanity");
1340 assert(top >= sd.region_to_addr(cp), "sanity");
1341
1342 HeapWord* const destination = cp->destination();
1343 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1344 const size_t compacted_region_live = pointer_delta(new_top, destination);
1345 const size_t compacted_region_used = pointer_delta(top,
1346 sd.region_to_addr(cp));
1347 const size_t reclaimable = compacted_region_used - compacted_region_live;
1348
1349 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1350 return double(reclaimable) / divisor;
1351 }
1352
1353 // Return the address of the end of the dense prefix, a.k.a. the start of the
1354 // compacted region. The address is always on a region boundary.
1355 //
1356 // Completely full regions at the left are skipped, since no compaction can
1357 // occur in those regions. Then the maximum amount of dead wood to allow is
1358 // computed, based on the density (amount live / capacity) of the generation;
1359 // the region with approximately that amount of dead space to the left is
1360 // identified as the limit region. Regions between the last completely full
1361 // region and the limit region are scanned and the one that has the best
1362 // (maximum) reclaimed_ratio() is selected.
1363 HeapWord*
1364 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1365 bool maximum_compaction)
1366 {
1367 const size_t region_size = ParallelCompactData::RegionSize;
1368 const ParallelCompactData& sd = summary_data();
1369
1370 const MutableSpace* const space = _space_info[id].space();
1371 HeapWord* const top = space->top();
1372 HeapWord* const top_aligned_up = sd.region_align_up(top);
1373 HeapWord* const new_top = _space_info[id].new_top();
1374 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1375 HeapWord* const bottom = space->bottom();
1376 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1377 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1378 const RegionData* const new_top_cp =
1379 sd.addr_to_region_ptr(new_top_aligned_up);
1380
1381 // Skip full regions at the beginning of the space--they are necessarily part
1382 // of the dense prefix.
1383 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1384 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1385 space->is_empty(), "no dead space allowed to the left");
1386 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1387 "region must have dead space");
1388
1389 // The gc number is saved whenever a maximum compaction is done, and used to
1390 // determine when the maximum compaction interval has expired. This avoids
1391 // successive max compactions for different reasons.
1392 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1393 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1394 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1395 total_invocations() == HeapFirstMaximumCompactionCount;
1396 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1397 _maximum_compaction_gc_num = total_invocations();
1398 return sd.region_to_addr(full_cp);
1399 }
1400
1401 const size_t space_live = pointer_delta(new_top, bottom);
1402 const size_t space_used = space->used_in_words();
1403 const size_t space_capacity = space->capacity_in_words();
1404
1405 const double density = double(space_live) / double(space_capacity);
1406 const size_t min_percent_free = MarkSweepDeadRatio;
1407 const double limiter = dead_wood_limiter(density, min_percent_free);
1408 const size_t dead_wood_max = space_used - space_live;
1409 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1410 dead_wood_max);
1411
1412 if (TraceParallelOldGCDensePrefix) {
1413 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1414 "space_cap=" SIZE_FORMAT,
1415 space_live, space_used,
1416 space_capacity);
1417 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1418 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1419 density, min_percent_free, limiter,
1420 dead_wood_max, dead_wood_limit);
1421 }
1422
1423 // Locate the region with the desired amount of dead space to the left.
1424 const RegionData* const limit_cp =
1425 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1426
1427 // Scan from the first region with dead space to the limit region and find the
1428 // one with the best (largest) reclaimed ratio.
1429 double best_ratio = 0.0;
1430 const RegionData* best_cp = full_cp;
1431 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1432 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1433 if (tmp_ratio > best_ratio) {
1434 best_cp = cp;
1435 best_ratio = tmp_ratio;
1436 }
1437 }
1438
1439 return sd.region_to_addr(best_cp);
1440 }
1441
1442 void PSParallelCompact::summarize_spaces_quick()
1443 {
1444 for (unsigned int i = 0; i < last_space_id; ++i) {
1445 const MutableSpace* space = _space_info[i].space();
1446 HeapWord** nta = _space_info[i].new_top_addr();
1447 bool result = _summary_data.summarize(_space_info[i].split_info(),
1448 space->bottom(), space->top(), NULL,
1449 space->bottom(), space->end(), nta);
1450 assert(result, "space must fit into itself");
1451 _space_info[i].set_dense_prefix(space->bottom());
1452 }
1453 }
1454
1455 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1456 {
1457 HeapWord* const dense_prefix_end = dense_prefix(id);
1458 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1459 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1460 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1461 // Only enough dead space is filled so that any remaining dead space to the
1462 // left is larger than the minimum filler object. (The remainder is filled
1463 // during the copy/update phase.)
1464 //
1465 // The size of the dead space to the right of the boundary is not a
1466 // concern, since compaction will be able to use whatever space is
1467 // available.
1468 //
1469 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1470 // surrounds the space to be filled with an object.
1471 //
1472 // In the 32-bit VM, each bit represents two 32-bit words:
1473 // +---+
1474 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1475 // end_bits: ... x x x | 0 | || 0 x x ...
1476 // +---+
1477 //
1478 // In the 64-bit VM, each bit represents one 64-bit word:
1479 // +------------+
1480 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1481 // end_bits: ... x x 1 | 0 || 0 | x x ...
1482 // +------------+
1483 // +-------+
1484 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1485 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1486 // +-------+
1487 // +-----------+
1488 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1489 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1490 // +-----------+
1491 // +-------+
1492 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1493 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1494 // +-------+
1495
1496 // Initially assume case a, c or e will apply.
1497 size_t obj_len = CollectedHeap::min_fill_size();
1498 HeapWord* obj_beg = dense_prefix_end - obj_len;
1499
1500 #ifdef _LP64
1501 if (MinObjAlignment > 1) { // object alignment > heap word size
1502 // Cases a, c or e.
1503 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1504 // Case b above.
1505 obj_beg = dense_prefix_end - 1;
1506 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1507 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1508 // Case d above.
1509 obj_beg = dense_prefix_end - 3;
1510 obj_len = 3;
1511 }
1512 #endif // #ifdef _LP64
1513
1514 CollectedHeap::fill_with_object(obj_beg, obj_len);
1515 _mark_bitmap.mark_obj(obj_beg, obj_len);
1516 _summary_data.add_obj(obj_beg, obj_len);
1517 assert(start_array(id) != NULL, "sanity");
1518 start_array(id)->allocate_block(obj_beg);
1519 }
1520 }
1521
1522 void
1523 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1524 {
1525 assert(id < last_space_id, "id out of range");
1526 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1527 "should have been reset in summarize_spaces_quick()");
1528
1529 const MutableSpace* space = _space_info[id].space();
1530 if (_space_info[id].new_top() != space->bottom()) {
1531 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1532 _space_info[id].set_dense_prefix(dense_prefix_end);
1533
1534 #ifndef PRODUCT
1535 if (TraceParallelOldGCDensePrefix) {
1536 print_dense_prefix_stats("ratio", id, maximum_compaction,
1537 dense_prefix_end);
1538 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1539 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1540 }
1541 #endif // #ifndef PRODUCT
1542
1543 // Recompute the summary data, taking into account the dense prefix. If
1544 // every last byte will be reclaimed, then the existing summary data which
1545 // compacts everything can be left in place.
1546 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1547 // If dead space crosses the dense prefix boundary, it is (at least
1548 // partially) filled with a dummy object, marked live and added to the
1549 // summary data. This simplifies the copy/update phase and must be done
1550 // before the final locations of objects are determined, to prevent
1551 // leaving a fragment of dead space that is too small to fill.
1552 fill_dense_prefix_end(id);
1553
1554 // Compute the destination of each Region, and thus each object.
1555 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1556 _summary_data.summarize(_space_info[id].split_info(),
1557 dense_prefix_end, space->top(), NULL,
1558 dense_prefix_end, space->end(),
1559 _space_info[id].new_top_addr());
1560 }
1561 }
1562
1563 if (log_develop_is_enabled(Trace, gc, compaction)) {
1564 const size_t region_size = ParallelCompactData::RegionSize;
1565 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1566 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1567 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1568 HeapWord* const new_top = _space_info[id].new_top();
1569 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1570 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1571 log_develop_trace(gc, compaction)(
1572 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1573 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1574 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1575 id, space->capacity_in_words(), p2i(dense_prefix_end),
1576 dp_region, dp_words / region_size,
1577 cr_words / region_size, p2i(new_top));
1578 }
1579 }
1580
1581 #ifndef PRODUCT
1582 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1583 HeapWord* dst_beg, HeapWord* dst_end,
1584 SpaceId src_space_id,
1585 HeapWord* src_beg, HeapWord* src_end)
1586 {
1587 log_develop_trace(gc, compaction)(
1588 "Summarizing %d [%s] into %d [%s]: "
1589 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1590 SIZE_FORMAT "-" SIZE_FORMAT " "
1591 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1592 SIZE_FORMAT "-" SIZE_FORMAT,
1593 src_space_id, space_names[src_space_id],
1594 dst_space_id, space_names[dst_space_id],
1595 p2i(src_beg), p2i(src_end),
1596 _summary_data.addr_to_region_idx(src_beg),
1597 _summary_data.addr_to_region_idx(src_end),
1598 p2i(dst_beg), p2i(dst_end),
1599 _summary_data.addr_to_region_idx(dst_beg),
1600 _summary_data.addr_to_region_idx(dst_end));
1601 }
1602 #endif // #ifndef PRODUCT
1603
1604 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1605 bool maximum_compaction)
1606 {
1607 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1608
1609 #ifdef ASSERT
1610 if (TraceParallelOldGCMarkingPhase) {
1611 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1612 "add_obj_bytes=" SIZE_FORMAT,
1613 add_obj_count, add_obj_size * HeapWordSize);
1614 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1615 "mark_bitmap_bytes=" SIZE_FORMAT,
1616 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1617 }
1618 #endif // #ifdef ASSERT
1619
1620 // Quick summarization of each space into itself, to see how much is live.
1621 summarize_spaces_quick();
1622
1623 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1624 NOT_PRODUCT(print_region_ranges());
1625 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1626
1627 // The amount of live data that will end up in old space (assuming it fits).
1628 size_t old_space_total_live = 0;
1629 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1630 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1631 _space_info[id].space()->bottom());
1632 }
1633
1634 MutableSpace* const old_space = _space_info[old_space_id].space();
1635 const size_t old_capacity = old_space->capacity_in_words();
1636 if (old_space_total_live > old_capacity) {
1637 // XXX - should also try to expand
1638 maximum_compaction = true;
1639 }
1640
1641 // Old generations.
1642 summarize_space(old_space_id, maximum_compaction);
1643
1644 // Summarize the remaining spaces in the young gen. The initial target space
1645 // is the old gen. If a space does not fit entirely into the target, then the
1646 // remainder is compacted into the space itself and that space becomes the new
1647 // target.
1648 SpaceId dst_space_id = old_space_id;
1649 HeapWord* dst_space_end = old_space->end();
1650 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1651 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1652 const MutableSpace* space = _space_info[id].space();
1653 const size_t live = pointer_delta(_space_info[id].new_top(),
1654 space->bottom());
1655 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1656
1657 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1658 SpaceId(id), space->bottom(), space->top());)
1659 if (live > 0 && live <= available) {
1660 // All the live data will fit.
1661 bool done = _summary_data.summarize(_space_info[id].split_info(),
1662 space->bottom(), space->top(),
1663 NULL,
1664 *new_top_addr, dst_space_end,
1665 new_top_addr);
1666 assert(done, "space must fit into old gen");
1667
1668 // Reset the new_top value for the space.
1669 _space_info[id].set_new_top(space->bottom());
1670 } else if (live > 0) {
1671 // Attempt to fit part of the source space into the target space.
1672 HeapWord* next_src_addr = NULL;
1673 bool done = _summary_data.summarize(_space_info[id].split_info(),
1674 space->bottom(), space->top(),
1675 &next_src_addr,
1676 *new_top_addr, dst_space_end,
1677 new_top_addr);
1678 assert(!done, "space should not fit into old gen");
1679 assert(next_src_addr != NULL, "sanity");
1680
1681 // The source space becomes the new target, so the remainder is compacted
1682 // within the space itself.
1683 dst_space_id = SpaceId(id);
1684 dst_space_end = space->end();
1685 new_top_addr = _space_info[id].new_top_addr();
1686 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1687 space->bottom(), dst_space_end,
1688 SpaceId(id), next_src_addr, space->top());)
1689 done = _summary_data.summarize(_space_info[id].split_info(),
1690 next_src_addr, space->top(),
1691 NULL,
1692 space->bottom(), dst_space_end,
1693 new_top_addr);
1694 assert(done, "space must fit when compacted into itself");
1695 assert(*new_top_addr <= space->top(), "usage should not grow");
1696 }
1697 }
1698
1699 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1700 NOT_PRODUCT(print_region_ranges());
1701 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1702 }
1703
1704 // This method should contain all heap-specific policy for invoking a full
1705 // collection. invoke_no_policy() will only attempt to compact the heap; it
1706 // will do nothing further. If we need to bail out for policy reasons, scavenge
1707 // before full gc, or any other specialized behavior, it needs to be added here.
1708 //
1709 // Note that this method should only be called from the vm_thread while at a
1710 // safepoint.
1711 //
1712 // Note that the all_soft_refs_clear flag in the collector policy
1713 // may be true because this method can be called without intervening
1714 // activity. For example when the heap space is tight and full measure
1715 // are being taken to free space.
1716 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1717 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1718 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1719 "should be in vm thread");
1720
1721 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1722 GCCause::Cause gc_cause = heap->gc_cause();
1723 assert(!heap->is_gc_active(), "not reentrant");
1724
1725 PSAdaptiveSizePolicy* policy = heap->size_policy();
1726 IsGCActiveMark mark;
1727
1728 if (ScavengeBeforeFullGC) {
1729 PSScavenge::invoke_no_policy();
1730 }
1731
1732 const bool clear_all_soft_refs =
1733 heap->soft_ref_policy()->should_clear_all_soft_refs();
1734
1735 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1736 maximum_heap_compaction);
1737 }
1738
1739 // This method contains no policy. You should probably
1740 // be calling invoke() instead.
1741 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1742 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1743 assert(ref_processor() != NULL, "Sanity");
1744
1745 if (GCLocker::check_active_before_gc()) {
1746 return false;
1747 }
1748
1749 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1750
1751 GCIdMark gc_id_mark;
1752 _gc_timer.register_gc_start();
1753 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1754
1755 TimeStamp marking_start;
1756 TimeStamp compaction_start;
1757 TimeStamp collection_exit;
1758
1759 GCCause::Cause gc_cause = heap->gc_cause();
1760 PSYoungGen* young_gen = heap->young_gen();
1761 PSOldGen* old_gen = heap->old_gen();
1762 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1763
1764 // The scope of casr should end after code that can change
1765 // CollectorPolicy::_should_clear_all_soft_refs.
1766 ClearedAllSoftRefs casr(maximum_heap_compaction,
1767 heap->soft_ref_policy());
1768
1769 if (ZapUnusedHeapArea) {
1770 // Save information needed to minimize mangling
1771 heap->record_gen_tops_before_GC();
1772 }
1773
1774 // Make sure data structures are sane, make the heap parsable, and do other
1775 // miscellaneous bookkeeping.
1776 pre_compact();
1777
1778 PreGCValues pre_gc_values(heap);
1779
1780 // Get the compaction manager reserved for the VM thread.
1781 ParCompactionManager* const vmthread_cm =
1782 ParCompactionManager::manager_array(gc_task_manager()->workers());
1783
1784 {
1785 ResourceMark rm;
1786 HandleMark hm;
1787
1788 // Set the number of GC threads to be used in this collection
1789 gc_task_manager()->set_active_gang();
1790 gc_task_manager()->task_idle_workers();
1791
1792 GCTraceCPUTime tcpu;
1793 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1794
1795 heap->pre_full_gc_dump(&_gc_timer);
1796
1797 TraceCollectorStats tcs(counters());
1798 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause);
1799
1800 if (log_is_enabled(Debug, gc, heap, exit)) {
1801 accumulated_time()->start();
1802 }
1803
1804 // Let the size policy know we're starting
1805 size_policy->major_collection_begin();
1806
1807 #if COMPILER2_OR_JVMCI
1808 DerivedPointerTable::clear();
1809 #endif
1810
1811 ref_processor()->enable_discovery();
1812 ref_processor()->setup_policy(maximum_heap_compaction);
1813
1814 bool marked_for_unloading = false;
1815
1816 marking_start.update();
1817 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1818
1819 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1820 && GCCause::is_user_requested_gc(gc_cause);
1821 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1822
1823 #if COMPILER2_OR_JVMCI
1824 assert(DerivedPointerTable::is_active(), "Sanity");
1825 DerivedPointerTable::set_active(false);
1826 #endif
1827
1828 // adjust_roots() updates Universe::_intArrayKlassObj which is
1829 // needed by the compaction for filling holes in the dense prefix.
1830 adjust_roots(vmthread_cm);
1831
1832 compaction_start.update();
1833 compact();
1834
1835 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1836 // done before resizing.
1837 post_compact();
1838
1839 // Let the size policy know we're done
1840 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1841
1842 if (UseAdaptiveSizePolicy) {
1843 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1844 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1845 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1846
1847 // Don't check if the size_policy is ready here. Let
1848 // the size_policy check that internally.
1849 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1850 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1851 // Swap the survivor spaces if from_space is empty. The
1852 // resize_young_gen() called below is normally used after
1853 // a successful young GC and swapping of survivor spaces;
1854 // otherwise, it will fail to resize the young gen with
1855 // the current implementation.
1856 if (young_gen->from_space()->is_empty()) {
1857 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1858 young_gen->swap_spaces();
1859 }
1860
1861 // Calculate optimal free space amounts
1862 assert(young_gen->max_size() >
1863 young_gen->from_space()->capacity_in_bytes() +
1864 young_gen->to_space()->capacity_in_bytes(),
1865 "Sizes of space in young gen are out-of-bounds");
1866
1867 size_t young_live = young_gen->used_in_bytes();
1868 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1869 size_t old_live = old_gen->used_in_bytes();
1870 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1871 size_t max_old_gen_size = old_gen->max_gen_size();
1872 size_t max_eden_size = young_gen->max_size() -
1873 young_gen->from_space()->capacity_in_bytes() -
1874 young_gen->to_space()->capacity_in_bytes();
1875
1876 // Used for diagnostics
1877 size_policy->clear_generation_free_space_flags();
1878
1879 size_policy->compute_generations_free_space(young_live,
1880 eden_live,
1881 old_live,
1882 cur_eden,
1883 max_old_gen_size,
1884 max_eden_size,
1885 true /* full gc*/);
1886
1887 size_policy->check_gc_overhead_limit(eden_live,
1888 max_old_gen_size,
1889 max_eden_size,
1890 true /* full gc*/,
1891 gc_cause,
1892 heap->soft_ref_policy());
1893
1894 size_policy->decay_supplemental_growth(true /* full gc*/);
1895
1896 heap->resize_old_gen(
1897 size_policy->calculated_old_free_size_in_bytes());
1898
1899 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1900 size_policy->calculated_survivor_size_in_bytes());
1901 }
1902
1903 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1904 }
1905
1906 if (UsePerfData) {
1907 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1908 counters->update_counters();
1909 counters->update_old_capacity(old_gen->capacity_in_bytes());
1910 counters->update_young_capacity(young_gen->capacity_in_bytes());
1911 }
1912
1913 heap->resize_all_tlabs();
1914
1915 // Resize the metaspace capacity after a collection
1916 MetaspaceGC::compute_new_size();
1917
1918 if (log_is_enabled(Debug, gc, heap, exit)) {
1919 accumulated_time()->stop();
1920 }
1921
1922 young_gen->print_used_change(pre_gc_values.young_gen_used());
1923 old_gen->print_used_change(pre_gc_values.old_gen_used());
1924 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used());
1925
1926 // Track memory usage and detect low memory
1927 MemoryService::track_memory_usage();
1928 heap->update_counters();
1929 gc_task_manager()->release_idle_workers();
1930
1931 heap->post_full_gc_dump(&_gc_timer);
1932 }
1933
1934 #ifdef ASSERT
1935 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1936 ParCompactionManager* const cm =
1937 ParCompactionManager::manager_array(int(i));
1938 assert(cm->marking_stack()->is_empty(), "should be empty");
1939 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1940 }
1941 #endif // ASSERT
1942
1943 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1944 HandleMark hm; // Discard invalid handles created during verification
1945 Universe::verify("After GC");
1946 }
1947
1948 // Re-verify object start arrays
1949 if (VerifyObjectStartArray &&
1950 VerifyAfterGC) {
1951 old_gen->verify_object_start_array();
1952 }
1953
1954 if (ZapUnusedHeapArea) {
1955 old_gen->object_space()->check_mangled_unused_area_complete();
1956 }
1957
1958 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1959
1960 collection_exit.update();
1961
1962 heap->print_heap_after_gc();
1963 heap->trace_heap_after_gc(&_gc_tracer);
1964
1965 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1966 marking_start.ticks(), compaction_start.ticks(),
1967 collection_exit.ticks());
1968 gc_task_manager()->print_task_time_stamps();
1969
1970 #ifdef TRACESPINNING
1971 ParallelTaskTerminator::print_termination_counts();
1972 #endif
1973
1974 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1975
1976 _gc_timer.register_gc_end();
1977
1978 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1979 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1980
1981 return true;
1982 }
1983
1984 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1985 PSYoungGen* young_gen,
1986 PSOldGen* old_gen) {
1987 MutableSpace* const eden_space = young_gen->eden_space();
1988 assert(!eden_space->is_empty(), "eden must be non-empty");
1989 assert(young_gen->virtual_space()->alignment() ==
1990 old_gen->virtual_space()->alignment(), "alignments do not match");
1991
1992 // We also return false when it's a heterogenous heap because old generation cannot absorb data from eden
1993 // when it is allocated on different memory (example, nv-dimm) than young.
1994 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary) ||
1995 ParallelScavengeHeap::heap()->ps_collector_policy()->is_hetero_heap()) {
1996 return false;
1997 }
1998
1999 // Both generations must be completely committed.
2000 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2001 return false;
2002 }
2003 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2004 return false;
2005 }
2006
2007 // Figure out how much to take from eden. Include the average amount promoted
2008 // in the total; otherwise the next young gen GC will simply bail out to a
2009 // full GC.
2010 const size_t alignment = old_gen->virtual_space()->alignment();
2011 const size_t eden_used = eden_space->used_in_bytes();
2012 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2013 const size_t absorb_size = align_up(eden_used + promoted, alignment);
2014 const size_t eden_capacity = eden_space->capacity_in_bytes();
2015
2016 if (absorb_size >= eden_capacity) {
2017 return false; // Must leave some space in eden.
2018 }
2019
2020 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2021 if (new_young_size < young_gen->min_gen_size()) {
2022 return false; // Respect young gen minimum size.
2023 }
2024
2025 log_trace(gc, ergo, heap)(" absorbing " SIZE_FORMAT "K: "
2026 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2027 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2028 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2029 absorb_size / K,
2030 eden_capacity / K, (eden_capacity - absorb_size) / K,
2031 young_gen->from_space()->used_in_bytes() / K,
2032 young_gen->to_space()->used_in_bytes() / K,
2033 young_gen->capacity_in_bytes() / K, new_young_size / K);
2034
2035 // Fill the unused part of the old gen.
2036 MutableSpace* const old_space = old_gen->object_space();
2037 HeapWord* const unused_start = old_space->top();
2038 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2039
2040 if (unused_words > 0) {
2041 if (unused_words < CollectedHeap::min_fill_size()) {
2042 return false; // If the old gen cannot be filled, must give up.
2043 }
2044 CollectedHeap::fill_with_objects(unused_start, unused_words);
2045 }
2046
2047 // Take the live data from eden and set both top and end in the old gen to
2048 // eden top. (Need to set end because reset_after_change() mangles the region
2049 // from end to virtual_space->high() in debug builds).
2050 HeapWord* const new_top = eden_space->top();
2051 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2052 absorb_size);
2053 young_gen->reset_after_change();
2054 old_space->set_top(new_top);
2055 old_space->set_end(new_top);
2056 old_gen->reset_after_change();
2057
2058 // Update the object start array for the filler object and the data from eden.
2059 ObjectStartArray* const start_array = old_gen->start_array();
2060 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2061 start_array->allocate_block(p);
2062 }
2063
2064 // Could update the promoted average here, but it is not typically updated at
2065 // full GCs and the value to use is unclear. Something like
2066 //
2067 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2068
2069 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2070 return true;
2071 }
2072
2073 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2074 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2075 "shouldn't return NULL");
2076 return ParallelScavengeHeap::gc_task_manager();
2077 }
2078
2079 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
2080 private:
2081 GCTaskQueue* _q;
2082
2083 public:
2084 PCAddThreadRootsMarkingTaskClosure(GCTaskQueue* q) : _q(q) { }
2085 void do_thread(Thread* t) {
2086 _q->enqueue(new ThreadRootsMarkingTask(t));
2087 }
2088 };
2089
2090 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2091 bool maximum_heap_compaction,
2092 ParallelOldTracer *gc_tracer) {
2093 // Recursively traverse all live objects and mark them
2094 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2095
2096 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2097 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2098 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2099 TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2100 TaskTerminator terminator(active_gc_threads, qset);
2101
2102 PCMarkAndPushClosure mark_and_push_closure(cm);
2103 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2104
2105 // Need new claim bits before marking starts.
2106 ClassLoaderDataGraph::clear_claimed_marks();
2107
2108 {
2109 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2110
2111 ParallelScavengeHeap::ParStrongRootsScope psrs;
2112
2113 GCTaskQueue* q = GCTaskQueue::create();
2114
2115 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2116 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2117 // We scan the thread roots in parallel
2118 PCAddThreadRootsMarkingTaskClosure cl(q);
2119 Threads::java_threads_and_vm_thread_do(&cl);
2120 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2121 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2122 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2123 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2124 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2125 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2126
2127 if (active_gc_threads > 1) {
2128 for (uint j = 0; j < active_gc_threads; j++) {
2129 q->enqueue(new StealMarkingTask(terminator.terminator()));
2130 }
2131 }
2132
2133 gc_task_manager()->execute_and_wait(q);
2134 }
2135
2136 // Process reference objects found during marking
2137 {
2138 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2139
2140 ReferenceProcessorStats stats;
2141 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
2142
2143 if (ref_processor()->processing_is_mt()) {
2144 ref_processor()->set_active_mt_degree(active_gc_threads);
2145
2146 RefProcTaskExecutor task_executor;
2147 stats = ref_processor()->process_discovered_references(
2148 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2149 &task_executor, &pt);
2150 } else {
2151 stats = ref_processor()->process_discovered_references(
2152 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2153 &pt);
2154 }
2155
2156 gc_tracer->report_gc_reference_stats(stats);
2157 pt.print_all_references();
2158 }
2159
2160 // This is the point where the entire marking should have completed.
2161 assert(cm->marking_stacks_empty(), "Marking should have completed");
2162
2163 {
2164 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
2165 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
2166 }
2167
2168 {
2169 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2170
2171 // Follow system dictionary roots and unload classes.
2172 bool purged_class = SystemDictionary::do_unloading(&_gc_timer);
2173
2174 // Unload nmethods.
2175 CodeCache::do_unloading(is_alive_closure(), purged_class);
2176
2177 // Prune dead klasses from subklass/sibling/implementor lists.
2178 Klass::clean_weak_klass_links(purged_class);
2179 }
2180
2181 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2182 }
2183
2184 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2185 // Adjust the pointers to reflect the new locations
2186 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2187
2188 // Need new claim bits when tracing through and adjusting pointers.
2189 ClassLoaderDataGraph::clear_claimed_marks();
2190
2191 PCAdjustPointerClosure oop_closure(cm);
2192
2193 // General strong roots.
2194 Universe::oops_do(&oop_closure);
2195 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles
2196 Threads::oops_do(&oop_closure, NULL);
2197 ObjectSynchronizer::oops_do(&oop_closure);
2198 Management::oops_do(&oop_closure);
2199 JvmtiExport::oops_do(&oop_closure);
2200 SystemDictionary::oops_do(&oop_closure);
2201 CLDToOopClosure cld_closure(&oop_closure, ClassLoaderData::_claim_strong);
2202 ClassLoaderDataGraph::cld_do(&cld_closure);
2203
2204 // Now adjust pointers in remaining weak roots. (All of which should
2205 // have been cleared if they pointed to non-surviving objects.)
2206 WeakProcessor::oops_do(&oop_closure);
2207
2208 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2209 CodeCache::blobs_do(&adjust_from_blobs);
2210 AOTLoader::oops_do(&oop_closure);
2211 ref_processor()->weak_oops_do(&oop_closure);
2212 // Roots were visited so references into the young gen in roots
2213 // may have been scanned. Process them also.
2214 // Should the reference processor have a span that excludes
2215 // young gen objects?
2216 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2217 }
2218
2219 // Helper class to print 8 region numbers per line and then print the total at the end.
2220 class FillableRegionLogger : public StackObj {
2221 private:
2222 Log(gc, compaction) log;
2223 static const int LineLength = 8;
2224 size_t _regions[LineLength];
2225 int _next_index;
2226 bool _enabled;
2227 size_t _total_regions;
2228 public:
2229 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
2230 ~FillableRegionLogger() {
2231 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2232 }
2233
2234 void print_line() {
2235 if (!_enabled || _next_index == 0) {
2236 return;
2237 }
2238 FormatBuffer<> line("Fillable: ");
2239 for (int i = 0; i < _next_index; i++) {
2240 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2241 }
2242 log.trace("%s", line.buffer());
2243 _next_index = 0;
2244 }
2245
2246 void handle(size_t region) {
2247 if (!_enabled) {
2248 return;
2249 }
2250 _regions[_next_index++] = region;
2251 if (_next_index == LineLength) {
2252 print_line();
2253 }
2254 _total_regions++;
2255 }
2256 };
2257
2258 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2259 uint parallel_gc_threads)
2260 {
2261 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2262
2263 // Find the threads that are active
2264 unsigned int which = 0;
2265
2266 // Find all regions that are available (can be filled immediately) and
2267 // distribute them to the thread stacks. The iteration is done in reverse
2268 // order (high to low) so the regions will be removed in ascending order.
2269
2270 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2271
2272 which = 0;
2273 // id + 1 is used to test termination so unsigned can
2274 // be used with an old_space_id == 0.
2275 FillableRegionLogger region_logger;
2276 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2277 SpaceInfo* const space_info = _space_info + id;
2278 MutableSpace* const space = space_info->space();
2279 HeapWord* const new_top = space_info->new_top();
2280
2281 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2282 const size_t end_region =
2283 sd.addr_to_region_idx(sd.region_align_up(new_top));
2284
2285 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2286 if (sd.region(cur)->claim_unsafe()) {
2287 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2288 cm->region_stack()->push(cur);
2289 region_logger.handle(cur);
2290 // Assign regions to tasks in round-robin fashion.
2291 if (++which == parallel_gc_threads) {
2292 which = 0;
2293 }
2294 }
2295 }
2296 region_logger.print_line();
2297 }
2298 }
2299
2300 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2301
2302 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2303 uint parallel_gc_threads) {
2304 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2305
2306 ParallelCompactData& sd = PSParallelCompact::summary_data();
2307
2308 // Iterate over all the spaces adding tasks for updating
2309 // regions in the dense prefix. Assume that 1 gc thread
2310 // will work on opening the gaps and the remaining gc threads
2311 // will work on the dense prefix.
2312 unsigned int space_id;
2313 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2314 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2315 const MutableSpace* const space = _space_info[space_id].space();
2316
2317 if (dense_prefix_end == space->bottom()) {
2318 // There is no dense prefix for this space.
2319 continue;
2320 }
2321
2322 // The dense prefix is before this region.
2323 size_t region_index_end_dense_prefix =
2324 sd.addr_to_region_idx(dense_prefix_end);
2325 RegionData* const dense_prefix_cp =
2326 sd.region(region_index_end_dense_prefix);
2327 assert(dense_prefix_end == space->end() ||
2328 dense_prefix_cp->available() ||
2329 dense_prefix_cp->claimed(),
2330 "The region after the dense prefix should always be ready to fill");
2331
2332 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2333
2334 // Is there dense prefix work?
2335 size_t total_dense_prefix_regions =
2336 region_index_end_dense_prefix - region_index_start;
2337 // How many regions of the dense prefix should be given to
2338 // each thread?
2339 if (total_dense_prefix_regions > 0) {
2340 uint tasks_for_dense_prefix = 1;
2341 if (total_dense_prefix_regions <=
2342 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2343 // Don't over partition. This assumes that
2344 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2345 // so there are not many regions to process.
2346 tasks_for_dense_prefix = parallel_gc_threads;
2347 } else {
2348 // Over partition
2349 tasks_for_dense_prefix = parallel_gc_threads *
2350 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2351 }
2352 size_t regions_per_thread = total_dense_prefix_regions /
2353 tasks_for_dense_prefix;
2354 // Give each thread at least 1 region.
2355 if (regions_per_thread == 0) {
2356 regions_per_thread = 1;
2357 }
2358
2359 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2360 if (region_index_start >= region_index_end_dense_prefix) {
2361 break;
2362 }
2363 // region_index_end is not processed
2364 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2365 region_index_end_dense_prefix);
2366 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2367 region_index_start,
2368 region_index_end));
2369 region_index_start = region_index_end;
2370 }
2371 }
2372 // This gets any part of the dense prefix that did not
2373 // fit evenly.
2374 if (region_index_start < region_index_end_dense_prefix) {
2375 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2376 region_index_start,
2377 region_index_end_dense_prefix));
2378 }
2379 }
2380 }
2381
2382 void PSParallelCompact::enqueue_region_stealing_tasks(
2383 GCTaskQueue* q,
2384 ParallelTaskTerminator* terminator_ptr,
2385 uint parallel_gc_threads) {
2386 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2387
2388 // Once a thread has drained it's stack, it should try to steal regions from
2389 // other threads.
2390 for (uint j = 0; j < parallel_gc_threads; j++) {
2391 q->enqueue(new CompactionWithStealingTask(terminator_ptr));
2392 }
2393 }
2394
2395 #ifdef ASSERT
2396 // Write a histogram of the number of times the block table was filled for a
2397 // region.
2398 void PSParallelCompact::write_block_fill_histogram()
2399 {
2400 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2401 return;
2402 }
2403
2404 Log(gc, compaction) log;
2405 ResourceMark rm;
2406 LogStream ls(log.trace());
2407 outputStream* out = &ls;
2408
2409 typedef ParallelCompactData::RegionData rd_t;
2410 ParallelCompactData& sd = summary_data();
2411
2412 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2413 MutableSpace* const spc = _space_info[id].space();
2414 if (spc->bottom() != spc->top()) {
2415 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2416 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2417 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2418
2419 size_t histo[5] = { 0, 0, 0, 0, 0 };
2420 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2421 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2422
2423 for (const rd_t* cur = beg; cur < end; ++cur) {
2424 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2425 }
2426 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2427 for (size_t i = 0; i < histo_len; ++i) {
2428 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2429 histo[i], 100.0 * histo[i] / region_cnt);
2430 }
2431 out->cr();
2432 }
2433 }
2434 }
2435 #endif // #ifdef ASSERT
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 parallel_gc_threads = heap->gc_task_manager()->workers();
2444 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2445 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2446 TaskTerminator terminator(active_gc_threads, qset);
2447
2448 GCTaskQueue* q = GCTaskQueue::create();
2449 prepare_region_draining_tasks(q, active_gc_threads);
2450 enqueue_dense_prefix_tasks(q, active_gc_threads);
2451 enqueue_region_stealing_tasks(q, terminator.terminator(), active_gc_threads);
2452
2453 {
2454 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2455
2456 gc_task_manager()->execute_and_wait(q);
2457
2458 #ifdef ASSERT
2459 // Verify that all regions have been processed before the deferred updates.
2460 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2461 verify_complete(SpaceId(id));
2462 }
2463 #endif
2464 }
2465
2466 {
2467 // Update the deferred objects, if any. Any compaction manager can be used.
2468 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2469 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2470 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2471 update_deferred_objects(cm, SpaceId(id));
2472 }
2473 }
2474
2475 DEBUG_ONLY(write_block_fill_histogram());
2476 }
2477
2478 #ifdef ASSERT
2479 void PSParallelCompact::verify_complete(SpaceId space_id) {
2480 // All Regions between space bottom() to new_top() should be marked as filled
2481 // and all Regions between new_top() and top() should be available (i.e.,
2482 // should have been emptied).
2483 ParallelCompactData& sd = summary_data();
2484 SpaceInfo si = _space_info[space_id];
2485 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2486 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2487 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2488 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2489 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2490
2491 bool issued_a_warning = false;
2492
2493 size_t cur_region;
2494 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2495 const RegionData* const c = sd.region(cur_region);
2496 if (!c->completed()) {
2497 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2498 cur_region, c->destination_count());
2499 issued_a_warning = true;
2500 }
2501 }
2502
2503 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2504 const RegionData* const c = sd.region(cur_region);
2505 if (!c->available()) {
2506 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2507 cur_region, c->destination_count());
2508 issued_a_warning = true;
2509 }
2510 }
2511
2512 if (issued_a_warning) {
2513 print_region_ranges();
2514 }
2515 }
2516 #endif // #ifdef ASSERT
2517
2518 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2519 _start_array->allocate_block(addr);
2520 compaction_manager()->update_contents(oop(addr));
2521 }
2522
2523 // Update interior oops in the ranges of regions [beg_region, end_region).
2524 void
2525 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2526 SpaceId space_id,
2527 size_t beg_region,
2528 size_t end_region) {
2529 ParallelCompactData& sd = summary_data();
2530 ParMarkBitMap* const mbm = mark_bitmap();
2531
2532 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2533 HeapWord* const end_addr = sd.region_to_addr(end_region);
2534 assert(beg_region <= end_region, "bad region range");
2535 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2536
2537 #ifdef ASSERT
2538 // Claim the regions to avoid triggering an assert when they are marked as
2539 // filled.
2540 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2541 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2542 }
2543 #endif // #ifdef ASSERT
2544
2545 if (beg_addr != space(space_id)->bottom()) {
2546 // Find the first live object or block of dead space that *starts* in this
2547 // range of regions. If a partial object crosses onto the region, skip it;
2548 // it will be marked for 'deferred update' when the object head is
2549 // processed. If dead space crosses onto the region, it is also skipped; it
2550 // will be filled when the prior region is processed. If neither of those
2551 // apply, the first word in the region is the start of a live object or dead
2552 // space.
2553 assert(beg_addr > space(space_id)->bottom(), "sanity");
2554 const RegionData* const cp = sd.region(beg_region);
2555 if (cp->partial_obj_size() != 0) {
2556 beg_addr = sd.partial_obj_end(beg_region);
2557 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2558 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2559 }
2560 }
2561
2562 if (beg_addr < end_addr) {
2563 // A live object or block of dead space starts in this range of Regions.
2564 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2565
2566 // Create closures and iterate.
2567 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2568 FillClosure fill_closure(cm, space_id);
2569 ParMarkBitMap::IterationStatus status;
2570 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2571 dense_prefix_end);
2572 if (status == ParMarkBitMap::incomplete) {
2573 update_closure.do_addr(update_closure.source());
2574 }
2575 }
2576
2577 // Mark the regions as filled.
2578 RegionData* const beg_cp = sd.region(beg_region);
2579 RegionData* const end_cp = sd.region(end_region);
2580 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2581 cp->set_completed();
2582 }
2583 }
2584
2585 // Return the SpaceId for the space containing addr. If addr is not in the
2586 // heap, last_space_id is returned. In debug mode it expects the address to be
2587 // in the heap and asserts such.
2588 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2589 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2590
2591 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2592 if (_space_info[id].space()->contains(addr)) {
2593 return SpaceId(id);
2594 }
2595 }
2596
2597 assert(false, "no space contains the addr");
2598 return last_space_id;
2599 }
2600
2601 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2602 SpaceId id) {
2603 assert(id < last_space_id, "bad space id");
2604
2605 ParallelCompactData& sd = summary_data();
2606 const SpaceInfo* const space_info = _space_info + id;
2607 ObjectStartArray* const start_array = space_info->start_array();
2608
2609 const MutableSpace* const space = space_info->space();
2610 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2611 HeapWord* const beg_addr = space_info->dense_prefix();
2612 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2613
2614 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2615 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2616 const RegionData* cur_region;
2617 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2618 HeapWord* const addr = cur_region->deferred_obj_addr();
2619 if (addr != NULL) {
2620 if (start_array != NULL) {
2621 start_array->allocate_block(addr);
2622 }
2623 cm->update_contents(oop(addr));
2624 assert(oopDesc::is_oop_or_null(oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2625 }
2626 }
2627 }
2628
2629 // Skip over count live words starting from beg, and return the address of the
2630 // next live word. Unless marked, the word corresponding to beg is assumed to
2631 // be dead. Callers must either ensure beg does not correspond to the middle of
2632 // an object, or account for those live words in some other way. Callers must
2633 // also ensure that there are enough live words in the range [beg, end) to skip.
2634 HeapWord*
2635 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2636 {
2637 assert(count > 0, "sanity");
2638
2639 ParMarkBitMap* m = mark_bitmap();
2640 idx_t bits_to_skip = m->words_to_bits(count);
2641 idx_t cur_beg = m->addr_to_bit(beg);
2642 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2643
2644 do {
2645 cur_beg = m->find_obj_beg(cur_beg, search_end);
2646 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2647 const size_t obj_bits = cur_end - cur_beg + 1;
2648 if (obj_bits > bits_to_skip) {
2649 return m->bit_to_addr(cur_beg + bits_to_skip);
2650 }
2651 bits_to_skip -= obj_bits;
2652 cur_beg = cur_end + 1;
2653 } while (bits_to_skip > 0);
2654
2655 // Skipping the desired number of words landed just past the end of an object.
2656 // Find the start of the next object.
2657 cur_beg = m->find_obj_beg(cur_beg, search_end);
2658 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2659 return m->bit_to_addr(cur_beg);
2660 }
2661
2662 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2663 SpaceId src_space_id,
2664 size_t src_region_idx)
2665 {
2666 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2667
2668 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2669 if (split_info.dest_region_addr() == dest_addr) {
2670 // The partial object ending at the split point contains the first word to
2671 // be copied to dest_addr.
2672 return split_info.first_src_addr();
2673 }
2674
2675 const ParallelCompactData& sd = summary_data();
2676 ParMarkBitMap* const bitmap = mark_bitmap();
2677 const size_t RegionSize = ParallelCompactData::RegionSize;
2678
2679 assert(sd.is_region_aligned(dest_addr), "not aligned");
2680 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2681 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2682 HeapWord* const src_region_destination = src_region_ptr->destination();
2683
2684 assert(dest_addr >= src_region_destination, "wrong src region");
2685 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2686
2687 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2688 HeapWord* const src_region_end = src_region_beg + RegionSize;
2689
2690 HeapWord* addr = src_region_beg;
2691 if (dest_addr == src_region_destination) {
2692 // Return the first live word in the source region.
2693 if (partial_obj_size == 0) {
2694 addr = bitmap->find_obj_beg(addr, src_region_end);
2695 assert(addr < src_region_end, "no objects start in src region");
2696 }
2697 return addr;
2698 }
2699
2700 // Must skip some live data.
2701 size_t words_to_skip = dest_addr - src_region_destination;
2702 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2703
2704 if (partial_obj_size >= words_to_skip) {
2705 // All the live words to skip are part of the partial object.
2706 addr += words_to_skip;
2707 if (partial_obj_size == words_to_skip) {
2708 // Find the first live word past the partial object.
2709 addr = bitmap->find_obj_beg(addr, src_region_end);
2710 assert(addr < src_region_end, "wrong src region");
2711 }
2712 return addr;
2713 }
2714
2715 // Skip over the partial object (if any).
2716 if (partial_obj_size != 0) {
2717 words_to_skip -= partial_obj_size;
2718 addr += partial_obj_size;
2719 }
2720
2721 // Skip over live words due to objects that start in the region.
2722 addr = skip_live_words(addr, src_region_end, words_to_skip);
2723 assert(addr < src_region_end, "wrong src region");
2724 return addr;
2725 }
2726
2727 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2728 SpaceId src_space_id,
2729 size_t beg_region,
2730 HeapWord* end_addr)
2731 {
2732 ParallelCompactData& sd = summary_data();
2733
2734 #ifdef ASSERT
2735 MutableSpace* const src_space = _space_info[src_space_id].space();
2736 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2737 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2738 "src_space_id does not match beg_addr");
2739 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2740 "src_space_id does not match end_addr");
2741 #endif // #ifdef ASSERT
2742
2743 RegionData* const beg = sd.region(beg_region);
2744 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2745
2746 // Regions up to new_top() are enqueued if they become available.
2747 HeapWord* const new_top = _space_info[src_space_id].new_top();
2748 RegionData* const enqueue_end =
2749 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2750
2751 for (RegionData* cur = beg; cur < end; ++cur) {
2752 assert(cur->data_size() > 0, "region must have live data");
2753 cur->decrement_destination_count();
2754 if (cur < enqueue_end && cur->available() && cur->claim()) {
2755 cm->push_region(sd.region(cur));
2756 }
2757 }
2758 }
2759
2760 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2761 SpaceId& src_space_id,
2762 HeapWord*& src_space_top,
2763 HeapWord* end_addr)
2764 {
2765 typedef ParallelCompactData::RegionData RegionData;
2766
2767 ParallelCompactData& sd = PSParallelCompact::summary_data();
2768 const size_t region_size = ParallelCompactData::RegionSize;
2769
2770 size_t src_region_idx = 0;
2771
2772 // Skip empty regions (if any) up to the top of the space.
2773 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2774 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2775 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2776 const RegionData* const top_region_ptr =
2777 sd.addr_to_region_ptr(top_aligned_up);
2778 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2779 ++src_region_ptr;
2780 }
2781
2782 if (src_region_ptr < top_region_ptr) {
2783 // The next source region is in the current space. Update src_region_idx
2784 // and the source address to match src_region_ptr.
2785 src_region_idx = sd.region(src_region_ptr);
2786 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2787 if (src_region_addr > closure.source()) {
2788 closure.set_source(src_region_addr);
2789 }
2790 return src_region_idx;
2791 }
2792
2793 // Switch to a new source space and find the first non-empty region.
2794 unsigned int space_id = src_space_id + 1;
2795 assert(space_id < last_space_id, "not enough spaces");
2796
2797 HeapWord* const destination = closure.destination();
2798
2799 do {
2800 MutableSpace* space = _space_info[space_id].space();
2801 HeapWord* const bottom = space->bottom();
2802 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2803
2804 // Iterate over the spaces that do not compact into themselves.
2805 if (bottom_cp->destination() != bottom) {
2806 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2807 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2808
2809 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2810 if (src_cp->live_obj_size() > 0) {
2811 // Found it.
2812 assert(src_cp->destination() == destination,
2813 "first live obj in the space must match the destination");
2814 assert(src_cp->partial_obj_size() == 0,
2815 "a space cannot begin with a partial obj");
2816
2817 src_space_id = SpaceId(space_id);
2818 src_space_top = space->top();
2819 const size_t src_region_idx = sd.region(src_cp);
2820 closure.set_source(sd.region_to_addr(src_region_idx));
2821 return src_region_idx;
2822 } else {
2823 assert(src_cp->data_size() == 0, "sanity");
2824 }
2825 }
2826 }
2827 } while (++space_id < last_space_id);
2828
2829 assert(false, "no source region was found");
2830 return 0;
2831 }
2832
2833 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2834 {
2835 typedef ParMarkBitMap::IterationStatus IterationStatus;
2836 const size_t RegionSize = ParallelCompactData::RegionSize;
2837 ParMarkBitMap* const bitmap = mark_bitmap();
2838 ParallelCompactData& sd = summary_data();
2839 RegionData* const region_ptr = sd.region(region_idx);
2840
2841 // Get the items needed to construct the closure.
2842 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2843 SpaceId dest_space_id = space_id(dest_addr);
2844 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2845 HeapWord* new_top = _space_info[dest_space_id].new_top();
2846 assert(dest_addr < new_top, "sanity");
2847 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2848
2849 // Get the source region and related info.
2850 size_t src_region_idx = region_ptr->source_region();
2851 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2852 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2853
2854 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2855 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2856
2857 // Adjust src_region_idx to prepare for decrementing destination counts (the
2858 // destination count is not decremented when a region is copied to itself).
2859 if (src_region_idx == region_idx) {
2860 src_region_idx += 1;
2861 }
2862
2863 if (bitmap->is_unmarked(closure.source())) {
2864 // The first source word is in the middle of an object; copy the remainder
2865 // of the object or as much as will fit. The fact that pointer updates were
2866 // deferred will be noted when the object header is processed.
2867 HeapWord* const old_src_addr = closure.source();
2868 closure.copy_partial_obj();
2869 if (closure.is_full()) {
2870 decrement_destination_counts(cm, src_space_id, src_region_idx,
2871 closure.source());
2872 region_ptr->set_deferred_obj_addr(NULL);
2873 region_ptr->set_completed();
2874 return;
2875 }
2876
2877 HeapWord* const end_addr = sd.region_align_down(closure.source());
2878 if (sd.region_align_down(old_src_addr) != end_addr) {
2879 // The partial object was copied from more than one source region.
2880 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2881
2882 // Move to the next source region, possibly switching spaces as well. All
2883 // args except end_addr may be modified.
2884 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2885 end_addr);
2886 }
2887 }
2888
2889 do {
2890 HeapWord* const cur_addr = closure.source();
2891 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2892 src_space_top);
2893 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2894
2895 if (status == ParMarkBitMap::incomplete) {
2896 // The last obj that starts in the source region does not end in the
2897 // region.
2898 assert(closure.source() < end_addr, "sanity");
2899 HeapWord* const obj_beg = closure.source();
2900 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2901 src_space_top);
2902 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2903 if (obj_end < range_end) {
2904 // The end was found; the entire object will fit.
2905 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2906 assert(status != ParMarkBitMap::would_overflow, "sanity");
2907 } else {
2908 // The end was not found; the object will not fit.
2909 assert(range_end < src_space_top, "obj cannot cross space boundary");
2910 status = ParMarkBitMap::would_overflow;
2911 }
2912 }
2913
2914 if (status == ParMarkBitMap::would_overflow) {
2915 // The last object did not fit. Note that interior oop updates were
2916 // deferred, then copy enough of the object to fill the region.
2917 region_ptr->set_deferred_obj_addr(closure.destination());
2918 status = closure.copy_until_full(); // copies from closure.source()
2919
2920 decrement_destination_counts(cm, src_space_id, src_region_idx,
2921 closure.source());
2922 region_ptr->set_completed();
2923 return;
2924 }
2925
2926 if (status == ParMarkBitMap::full) {
2927 decrement_destination_counts(cm, src_space_id, src_region_idx,
2928 closure.source());
2929 region_ptr->set_deferred_obj_addr(NULL);
2930 region_ptr->set_completed();
2931 return;
2932 }
2933
2934 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2935
2936 // Move to the next source region, possibly switching spaces as well. All
2937 // args except end_addr may be modified.
2938 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2939 end_addr);
2940 } while (true);
2941 }
2942
2943 void PSParallelCompact::fill_blocks(size_t region_idx)
2944 {
2945 // Fill in the block table elements for the specified region. Each block
2946 // table element holds the number of live words in the region that are to the
2947 // left of the first object that starts in the block. Thus only blocks in
2948 // which an object starts need to be filled.
2949 //
2950 // The algorithm scans the section of the bitmap that corresponds to the
2951 // region, keeping a running total of the live words. When an object start is
2952 // found, if it's the first to start in the block that contains it, the
2953 // current total is written to the block table element.
2954 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2955 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2956 const size_t RegionSize = ParallelCompactData::RegionSize;
2957
2958 ParallelCompactData& sd = summary_data();
2959 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2960 if (partial_obj_size >= RegionSize) {
2961 return; // No objects start in this region.
2962 }
2963
2964 // Ensure the first loop iteration decides that the block has changed.
2965 size_t cur_block = sd.block_count();
2966
2967 const ParMarkBitMap* const bitmap = mark_bitmap();
2968
2969 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2970 assert((size_t)1 << Log2BitsPerBlock ==
2971 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2972
2973 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2974 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2975 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2976 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2977 while (beg_bit < range_end) {
2978 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2979 if (new_block != cur_block) {
2980 cur_block = new_block;
2981 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2982 }
2983
2984 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2985 if (end_bit < range_end - 1) {
2986 live_bits += end_bit - beg_bit + 1;
2987 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2988 } else {
2989 return;
2990 }
2991 }
2992 }
2993
2994 void
2995 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2996 const MutableSpace* sp = space(space_id);
2997 if (sp->is_empty()) {
2998 return;
2999 }
3000
3001 ParallelCompactData& sd = PSParallelCompact::summary_data();
3002 ParMarkBitMap* const bitmap = mark_bitmap();
3003 HeapWord* const dp_addr = dense_prefix(space_id);
3004 HeapWord* beg_addr = sp->bottom();
3005 HeapWord* end_addr = sp->top();
3006
3007 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3008
3009 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3010 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3011 if (beg_region < dp_region) {
3012 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3013 }
3014
3015 // The destination of the first live object that starts in the region is one
3016 // past the end of the partial object entering the region (if any).
3017 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3018 HeapWord* const new_top = _space_info[space_id].new_top();
3019 assert(new_top >= dest_addr, "bad new_top value");
3020 const size_t words = pointer_delta(new_top, dest_addr);
3021
3022 if (words > 0) {
3023 ObjectStartArray* start_array = _space_info[space_id].start_array();
3024 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3025
3026 ParMarkBitMap::IterationStatus status;
3027 status = bitmap->iterate(&closure, dest_addr, end_addr);
3028 assert(status == ParMarkBitMap::full, "iteration not complete");
3029 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3030 "live objects skipped because closure is full");
3031 }
3032 }
3033
3034 jlong PSParallelCompact::millis_since_last_gc() {
3035 // We need a monotonically non-decreasing time in ms but
3036 // os::javaTimeMillis() does not guarantee monotonicity.
3037 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3038 jlong ret_val = now - _time_of_last_gc;
3039 // XXX See note in genCollectedHeap::millis_since_last_gc().
3040 if (ret_val < 0) {
3041 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3042 return 0;
3043 }
3044 return ret_val;
3045 }
3046
3047 void PSParallelCompact::reset_millis_since_last_gc() {
3048 // We need a monotonically non-decreasing time in ms but
3049 // os::javaTimeMillis() does not guarantee monotonicity.
3050 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3051 }
3052
3053 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3054 {
3055 if (source() != destination()) {
3056 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3057 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3058 }
3059 update_state(words_remaining());
3060 assert(is_full(), "sanity");
3061 return ParMarkBitMap::full;
3062 }
3063
3064 void MoveAndUpdateClosure::copy_partial_obj()
3065 {
3066 size_t words = words_remaining();
3067
3068 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3069 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3070 if (end_addr < range_end) {
3071 words = bitmap()->obj_size(source(), end_addr);
3072 }
3073
3074 // This test is necessary; if omitted, the pointer updates to a partial object
3075 // that crosses the dense prefix boundary could be overwritten.
3076 if (source() != destination()) {
3077 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3078 Copy::aligned_conjoint_words(source(), destination(), words);
3079 }
3080 update_state(words);
3081 }
3082
3083 ParMarkBitMapClosure::IterationStatus
3084 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3085 assert(destination() != NULL, "sanity");
3086 assert(bitmap()->obj_size(addr) == words, "bad size");
3087
3088 _source = addr;
3089 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3090 destination(), "wrong destination");
3091
3092 if (words > words_remaining()) {
3093 return ParMarkBitMap::would_overflow;
3094 }
3095
3096 // The start_array must be updated even if the object is not moving.
3097 if (_start_array != NULL) {
3098 _start_array->allocate_block(destination());
3099 }
3100
3101 if (destination() != source()) {
3102 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3103 Copy::aligned_conjoint_words(source(), destination(), words);
3104 }
3105
3106 oop moved_oop = (oop) destination();
3107 compaction_manager()->update_contents(moved_oop);
3108 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3109
3110 update_state(words);
3111 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3112 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3113 }
3114
3115 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3116 ParCompactionManager* cm,
3117 PSParallelCompact::SpaceId space_id) :
3118 ParMarkBitMapClosure(mbm, cm),
3119 _space_id(space_id),
3120 _start_array(PSParallelCompact::start_array(space_id))
3121 {
3122 }
3123
3124 // Updates the references in the object to their new values.
3125 ParMarkBitMapClosure::IterationStatus
3126 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3127 do_addr(addr);
3128 return ParMarkBitMap::incomplete;
3129 }
3130
3131 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3132 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3133 _start_array(PSParallelCompact::start_array(space_id))
3134 {
3135 assert(space_id == PSParallelCompact::old_space_id,
3136 "cannot use FillClosure in the young gen");
3137 }
3138
3139 ParMarkBitMapClosure::IterationStatus
3140 FillClosure::do_addr(HeapWord* addr, size_t size) {
3141 CollectedHeap::fill_with_objects(addr, size);
3142 HeapWord* const end = addr + size;
3143 do {
3144 _start_array->allocate_block(addr);
3145 addr += oop(addr)->size();
3146 } while (addr < end);
3147 return ParMarkBitMap::incomplete;
3148 }