1 /*
2 * Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/stringTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
30 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"
31 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
33 #include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp"
34 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
35 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
36 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
37 #include "gc_implementation/parallelScavenge/psParallelCompact.inline.hpp"
38 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
39 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
40 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
41 #include "gc_implementation/shared/gcHeapSummary.hpp"
42 #include "gc_implementation/shared/gcTimer.hpp"
43 #include "gc_implementation/shared/gcTrace.hpp"
44 #include "gc_implementation/shared/gcTraceTime.hpp"
45 #include "gc_implementation/shared/isGCActiveMark.hpp"
46 #include "gc_implementation/shared/spaceDecorator.hpp"
47 #include "gc_interface/gcCause.hpp"
48 #include "memory/gcLocker.inline.hpp"
49 #include "memory/referencePolicy.hpp"
50 #include "memory/referenceProcessor.hpp"
51 #include "oops/instanceKlass.inline.hpp"
52 #include "oops/instanceMirrorKlass.inline.hpp"
53 #include "oops/methodData.hpp"
54 #include "oops/objArrayKlass.inline.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "runtime/atomic.inline.hpp"
57 #include "runtime/fprofiler.hpp"
58 #include "runtime/safepoint.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "services/management.hpp"
61 #include "services/memoryService.hpp"
62 #include "services/memTracker.hpp"
63 #include "utilities/events.hpp"
64 #include "utilities/stack.inline.hpp"
65
66 #include <math.h>
67
68 // All sizes are in HeapWords.
69 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
70 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
71 const size_t ParallelCompactData::RegionSizeBytes =
72 RegionSize << LogHeapWordSize;
73 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
74 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
75 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
76
77 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
78 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
79 const size_t ParallelCompactData::BlockSizeBytes =
80 BlockSize << LogHeapWordSize;
81 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
82 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
83 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
84
85 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
86 const size_t ParallelCompactData::Log2BlocksPerRegion =
87 Log2RegionSize - Log2BlockSize;
88
89 const ParallelCompactData::RegionData::region_sz_t
90 ParallelCompactData::RegionData::dc_shift = 27;
91
92 const ParallelCompactData::RegionData::region_sz_t
93 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
94
95 const ParallelCompactData::RegionData::region_sz_t
96 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
97
98 const ParallelCompactData::RegionData::region_sz_t
99 ParallelCompactData::RegionData::los_mask = ~dc_mask;
100
101 const ParallelCompactData::RegionData::region_sz_t
102 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
103
104 const ParallelCompactData::RegionData::region_sz_t
105 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
106
107 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
108 bool PSParallelCompact::_print_phases = false;
109
110 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
111 Klass* PSParallelCompact::_updated_int_array_klass_obj = NULL;
112
113 double PSParallelCompact::_dwl_mean;
114 double PSParallelCompact::_dwl_std_dev;
115 double PSParallelCompact::_dwl_first_term;
116 double PSParallelCompact::_dwl_adjustment;
117 #ifdef ASSERT
118 bool PSParallelCompact::_dwl_initialized = false;
119 #endif // #ifdef ASSERT
120
121 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
122 HeapWord* destination)
123 {
124 assert(src_region_idx != 0, "invalid src_region_idx");
125 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
126 assert(destination != NULL, "invalid destination argument");
127
128 _src_region_idx = src_region_idx;
129 _partial_obj_size = partial_obj_size;
130 _destination = destination;
131
132 // These fields may not be updated below, so make sure they're clear.
133 assert(_dest_region_addr == NULL, "should have been cleared");
134 assert(_first_src_addr == NULL, "should have been cleared");
135
136 // Determine the number of destination regions for the partial object.
137 HeapWord* const last_word = destination + partial_obj_size - 1;
138 const ParallelCompactData& sd = PSParallelCompact::summary_data();
139 HeapWord* const beg_region_addr = sd.region_align_down(destination);
140 HeapWord* const end_region_addr = sd.region_align_down(last_word);
141
142 if (beg_region_addr == end_region_addr) {
143 // One destination region.
144 _destination_count = 1;
145 if (end_region_addr == destination) {
146 // The destination falls on a region boundary, thus the first word of the
147 // partial object will be the first word copied to the destination region.
148 _dest_region_addr = end_region_addr;
149 _first_src_addr = sd.region_to_addr(src_region_idx);
150 }
151 } else {
152 // Two destination regions. When copied, the partial object will cross a
153 // destination region boundary, so a word somewhere within the partial
154 // object will be the first word copied to the second destination region.
155 _destination_count = 2;
156 _dest_region_addr = end_region_addr;
157 const size_t ofs = pointer_delta(end_region_addr, destination);
158 assert(ofs < _partial_obj_size, "sanity");
159 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
160 }
161 }
162
163 void SplitInfo::clear()
164 {
165 _src_region_idx = 0;
166 _partial_obj_size = 0;
167 _destination = NULL;
168 _destination_count = 0;
169 _dest_region_addr = NULL;
170 _first_src_addr = NULL;
171 assert(!is_valid(), "sanity");
172 }
173
174 #ifdef ASSERT
175 void SplitInfo::verify_clear()
176 {
177 assert(_src_region_idx == 0, "not clear");
178 assert(_partial_obj_size == 0, "not clear");
179 assert(_destination == NULL, "not clear");
180 assert(_destination_count == 0, "not clear");
181 assert(_dest_region_addr == NULL, "not clear");
182 assert(_first_src_addr == NULL, "not clear");
183 }
184 #endif // #ifdef ASSERT
185
186
187 void PSParallelCompact::print_on_error(outputStream* st) {
188 _mark_bitmap.print_on_error(st);
189 }
190
191 #ifndef PRODUCT
192 const char* PSParallelCompact::space_names[] = {
193 "old ", "eden", "from", "to "
194 };
195
196 void PSParallelCompact::print_region_ranges()
197 {
198 tty->print_cr("space bottom top end new_top");
199 tty->print_cr("------ ---------- ---------- ---------- ----------");
200
201 for (unsigned int id = 0; id < last_space_id; ++id) {
202 const MutableSpace* space = _space_info[id].space();
203 tty->print_cr("%u %s "
204 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
205 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
206 id, space_names[id],
207 summary_data().addr_to_region_idx(space->bottom()),
208 summary_data().addr_to_region_idx(space->top()),
209 summary_data().addr_to_region_idx(space->end()),
210 summary_data().addr_to_region_idx(_space_info[id].new_top()));
211 }
212 }
213
214 void
215 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
216 {
217 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
218 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
219
220 ParallelCompactData& sd = PSParallelCompact::summary_data();
221 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
222 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
223 REGION_IDX_FORMAT " " PTR_FORMAT " "
224 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
225 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
226 i, p2i(c->data_location()), dci, p2i(c->destination()),
227 c->partial_obj_size(), c->live_obj_size(),
228 c->data_size(), c->source_region(), c->destination_count());
229
230 #undef REGION_IDX_FORMAT
231 #undef REGION_DATA_FORMAT
232 }
233
234 void
235 print_generic_summary_data(ParallelCompactData& summary_data,
236 HeapWord* const beg_addr,
237 HeapWord* const end_addr)
238 {
239 size_t total_words = 0;
240 size_t i = summary_data.addr_to_region_idx(beg_addr);
241 const size_t last = summary_data.addr_to_region_idx(end_addr);
242 HeapWord* pdest = 0;
243
244 while (i <= last) {
245 ParallelCompactData::RegionData* c = summary_data.region(i);
246 if (c->data_size() != 0 || c->destination() != pdest) {
247 print_generic_summary_region(i, c);
248 total_words += c->data_size();
249 pdest = c->destination();
250 }
251 ++i;
252 }
253
254 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
255 }
256
257 void
258 print_generic_summary_data(ParallelCompactData& summary_data,
259 SpaceInfo* space_info)
260 {
261 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
262 const MutableSpace* space = space_info[id].space();
263 print_generic_summary_data(summary_data, space->bottom(),
264 MAX2(space->top(), space_info[id].new_top()));
265 }
266 }
267
268 void
269 print_initial_summary_region(size_t i,
270 const ParallelCompactData::RegionData* c,
271 bool newline = true)
272 {
273 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
274 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
275 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
276 i, p2i(c->destination()),
277 c->partial_obj_size(), c->live_obj_size(),
278 c->data_size(), c->source_region(), c->destination_count());
279 if (newline) tty->cr();
280 }
281
282 void
283 print_initial_summary_data(ParallelCompactData& summary_data,
284 const MutableSpace* space) {
285 if (space->top() == space->bottom()) {
286 return;
287 }
288
289 const size_t region_size = ParallelCompactData::RegionSize;
290 typedef ParallelCompactData::RegionData RegionData;
291 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
292 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
293 const RegionData* c = summary_data.region(end_region - 1);
294 HeapWord* end_addr = c->destination() + c->data_size();
295 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
296
297 // Print (and count) the full regions at the beginning of the space.
298 size_t full_region_count = 0;
299 size_t i = summary_data.addr_to_region_idx(space->bottom());
300 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
301 print_initial_summary_region(i, summary_data.region(i));
302 ++full_region_count;
303 ++i;
304 }
305
306 size_t live_to_right = live_in_space - full_region_count * region_size;
307
308 double max_reclaimed_ratio = 0.0;
309 size_t max_reclaimed_ratio_region = 0;
310 size_t max_dead_to_right = 0;
311 size_t max_live_to_right = 0;
312
313 // Print the 'reclaimed ratio' for regions while there is something live in
314 // the region or to the right of it. The remaining regions are empty (and
315 // uninteresting), and computing the ratio will result in division by 0.
316 while (i < end_region && live_to_right > 0) {
317 c = summary_data.region(i);
318 HeapWord* const region_addr = summary_data.region_to_addr(i);
319 const size_t used_to_right = pointer_delta(space->top(), region_addr);
320 const size_t dead_to_right = used_to_right - live_to_right;
321 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
322
323 if (reclaimed_ratio > max_reclaimed_ratio) {
324 max_reclaimed_ratio = reclaimed_ratio;
325 max_reclaimed_ratio_region = i;
326 max_dead_to_right = dead_to_right;
327 max_live_to_right = live_to_right;
328 }
329
330 print_initial_summary_region(i, c, false);
331 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
332 reclaimed_ratio, dead_to_right, live_to_right);
333
334 live_to_right -= c->data_size();
335 ++i;
336 }
337
338 // Any remaining regions are empty. Print one more if there is one.
339 if (i < end_region) {
340 print_initial_summary_region(i, summary_data.region(i));
341 }
342
343 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
344 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
345 max_reclaimed_ratio_region, max_dead_to_right,
346 max_live_to_right, max_reclaimed_ratio);
347 }
348
349 void
350 print_initial_summary_data(ParallelCompactData& summary_data,
351 SpaceInfo* space_info) {
352 unsigned int id = PSParallelCompact::old_space_id;
353 const MutableSpace* space;
354 do {
355 space = space_info[id].space();
356 print_initial_summary_data(summary_data, space);
357 } while (++id < PSParallelCompact::eden_space_id);
358
359 do {
360 space = space_info[id].space();
361 print_generic_summary_data(summary_data, space->bottom(), space->top());
362 } while (++id < PSParallelCompact::last_space_id);
363 }
364 #endif // #ifndef PRODUCT
365
366 #ifdef ASSERT
367 size_t add_obj_count;
368 size_t add_obj_size;
369 size_t mark_bitmap_count;
370 size_t mark_bitmap_size;
371 #endif // #ifdef ASSERT
372
373 ParallelCompactData::ParallelCompactData()
374 {
375 _region_start = 0;
376
377 _region_vspace = 0;
378 _reserved_byte_size = 0;
379 _region_data = 0;
380 _region_count = 0;
381
382 _block_vspace = 0;
383 _block_data = 0;
384 _block_count = 0;
385 }
386
387 bool ParallelCompactData::initialize(MemRegion covered_region)
388 {
389 _region_start = covered_region.start();
390 const size_t region_size = covered_region.word_size();
391 DEBUG_ONLY(_region_end = _region_start + region_size;)
392
393 assert(region_align_down(_region_start) == _region_start,
394 "region start not aligned");
395 assert((region_size & RegionSizeOffsetMask) == 0,
396 "region size not a multiple of RegionSize");
397
398 bool result = initialize_region_data(region_size) && initialize_block_data();
399 return result;
400 }
401
402 PSVirtualSpace*
403 ParallelCompactData::create_vspace(size_t count, size_t element_size)
404 {
405 const size_t raw_bytes = count * element_size;
406 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
407 const size_t granularity = os::vm_allocation_granularity();
408 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
409
410 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
411 MAX2(page_sz, granularity);
412 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
413 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
414 rs.size());
415
416 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
417
418 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
419 if (vspace != 0) {
420 if (vspace->expand_by(_reserved_byte_size)) {
421 return vspace;
422 }
423 delete vspace;
424 // Release memory reserved in the space.
425 rs.release();
426 }
427
428 return 0;
429 }
430
431 bool ParallelCompactData::initialize_region_data(size_t region_size)
432 {
433 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
434 _region_vspace = create_vspace(count, sizeof(RegionData));
435 if (_region_vspace != 0) {
436 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
437 _region_count = count;
438 return true;
439 }
440 return false;
441 }
442
443 bool ParallelCompactData::initialize_block_data()
444 {
445 assert(_region_count != 0, "region data must be initialized first");
446 const size_t count = _region_count << Log2BlocksPerRegion;
447 _block_vspace = create_vspace(count, sizeof(BlockData));
448 if (_block_vspace != 0) {
449 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
450 _block_count = count;
451 return true;
452 }
453 return false;
454 }
455
456 void ParallelCompactData::clear()
457 {
458 memset(_region_data, 0, _region_vspace->committed_size());
459 memset(_block_data, 0, _block_vspace->committed_size());
460 }
461
462 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
463 assert(beg_region <= _region_count, "beg_region out of range");
464 assert(end_region <= _region_count, "end_region out of range");
465 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
466
467 const size_t region_cnt = end_region - beg_region;
468 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
469
470 const size_t beg_block = beg_region * BlocksPerRegion;
471 const size_t block_cnt = region_cnt * BlocksPerRegion;
472 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
473 }
474
475 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
476 {
477 const RegionData* cur_cp = region(region_idx);
478 const RegionData* const end_cp = region(region_count() - 1);
479
480 HeapWord* result = region_to_addr(region_idx);
481 if (cur_cp < end_cp) {
482 do {
483 result += cur_cp->partial_obj_size();
484 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
485 }
486 return result;
487 }
488
489 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
490 {
491 const size_t obj_ofs = pointer_delta(addr, _region_start);
492 const size_t beg_region = obj_ofs >> Log2RegionSize;
493 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
494
495 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
496 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
497
498 if (beg_region == end_region) {
499 // All in one region.
500 _region_data[beg_region].add_live_obj(len);
501 return;
502 }
503
504 // First region.
505 const size_t beg_ofs = region_offset(addr);
506 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
507
508 Klass* klass = ((oop)addr)->klass();
509 // Middle regions--completely spanned by this object.
510 for (size_t region = beg_region + 1; region < end_region; ++region) {
511 _region_data[region].set_partial_obj_size(RegionSize);
512 _region_data[region].set_partial_obj_addr(addr);
513 }
514
515 // Last region.
516 const size_t end_ofs = region_offset(addr + len - 1);
517 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
518 _region_data[end_region].set_partial_obj_addr(addr);
519 }
520
521 void
522 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
523 {
524 assert(region_offset(beg) == 0, "not RegionSize aligned");
525 assert(region_offset(end) == 0, "not RegionSize aligned");
526
527 size_t cur_region = addr_to_region_idx(beg);
528 const size_t end_region = addr_to_region_idx(end);
529 HeapWord* addr = beg;
530 while (cur_region < end_region) {
531 _region_data[cur_region].set_destination(addr);
532 _region_data[cur_region].set_destination_count(0);
533 _region_data[cur_region].set_source_region(cur_region);
534 _region_data[cur_region].set_data_location(addr);
535
536 // Update live_obj_size so the region appears completely full.
537 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
538 _region_data[cur_region].set_live_obj_size(live_size);
539
540 ++cur_region;
541 addr += RegionSize;
542 }
543 }
544
545 // Find the point at which a space can be split and, if necessary, record the
546 // split point.
547 //
548 // If the current src region (which overflowed the destination space) doesn't
549 // have a partial object, the split point is at the beginning of the current src
550 // region (an "easy" split, no extra bookkeeping required).
551 //
552 // If the current src region has a partial object, the split point is in the
553 // region where that partial object starts (call it the split_region). If
554 // split_region has a partial object, then the split point is just after that
555 // partial object (a "hard" split where we have to record the split data and
556 // zero the partial_obj_size field). With a "hard" split, we know that the
557 // partial_obj ends within split_region because the partial object that caused
558 // the overflow starts in split_region. If split_region doesn't have a partial
559 // obj, then the split is at the beginning of split_region (another "easy"
560 // split).
561 HeapWord*
562 ParallelCompactData::summarize_split_space(size_t src_region,
563 SplitInfo& split_info,
564 HeapWord* destination,
565 HeapWord* target_end,
566 HeapWord** target_next)
567 {
568 assert(destination <= target_end, "sanity");
569 assert(destination + _region_data[src_region].data_size() > target_end,
570 "region should not fit into target space");
571 assert(is_region_aligned(target_end), "sanity");
572
573 size_t split_region = src_region;
574 HeapWord* split_destination = destination;
575 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
576
577 if (destination + partial_obj_size > target_end) {
578 // The split point is just after the partial object (if any) in the
579 // src_region that contains the start of the object that overflowed the
580 // destination space.
581 //
582 // Find the start of the "overflow" object and set split_region to the
583 // region containing it.
584 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
585 split_region = addr_to_region_idx(overflow_obj);
586
587 // Clear the source_region field of all destination regions whose first word
588 // came from data after the split point (a non-null source_region field
589 // implies a region must be filled).
590 //
591 // An alternative to the simple loop below: clear during post_compact(),
592 // which uses memcpy instead of individual stores, and is easy to
593 // parallelize. (The downside is that it clears the entire RegionData
594 // object as opposed to just one field.)
595 //
596 // post_compact() would have to clear the summary data up to the highest
597 // address that was written during the summary phase, which would be
598 //
599 // max(top, max(new_top, clear_top))
600 //
601 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
602 // to target_end.
603 const RegionData* const sr = region(split_region);
604 const size_t beg_idx =
605 addr_to_region_idx(region_align_up(sr->destination() +
606 sr->partial_obj_size()));
607 const size_t end_idx = addr_to_region_idx(target_end);
608
609 if (TraceParallelOldGCSummaryPhase) {
610 gclog_or_tty->print_cr("split: clearing source_region field in ["
611 SIZE_FORMAT ", " SIZE_FORMAT ")",
612 beg_idx, end_idx);
613 }
614 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
615 _region_data[idx].set_source_region(0);
616 }
617
618 // Set split_destination and partial_obj_size to reflect the split region.
619 split_destination = sr->destination();
620 partial_obj_size = sr->partial_obj_size();
621 }
622
623 // The split is recorded only if a partial object extends onto the region.
624 if (partial_obj_size != 0) {
625 _region_data[split_region].set_partial_obj_size(0);
626 split_info.record(split_region, partial_obj_size, split_destination);
627 }
628
629 // Setup the continuation addresses.
630 *target_next = split_destination + partial_obj_size;
631 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
632
633 if (TraceParallelOldGCSummaryPhase) {
634 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
635 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
636 " pos=" SIZE_FORMAT,
637 split_type, p2i(source_next), split_region,
638 partial_obj_size);
639 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
640 " tn=" PTR_FORMAT,
641 split_type, p2i(split_destination),
642 addr_to_region_idx(split_destination),
643 p2i(*target_next));
644
645 if (partial_obj_size != 0) {
646 HeapWord* const po_beg = split_info.destination();
647 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
648 gclog_or_tty->print_cr("%s split: "
649 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
650 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
651 split_type,
652 p2i(po_beg), addr_to_region_idx(po_beg),
653 p2i(po_end), addr_to_region_idx(po_end));
654 }
655 }
656
657 return source_next;
658 }
659
660 bool ParallelCompactData::summarize(SplitInfo& split_info,
661 HeapWord* source_beg, HeapWord* source_end,
662 HeapWord** source_next,
663 HeapWord* target_beg, HeapWord* target_end,
664 HeapWord** target_next)
665 {
666 if (TraceParallelOldGCSummaryPhase) {
667 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
668 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
669 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
670 p2i(source_beg), p2i(source_end), p2i(source_next_val),
671 p2i(target_beg), p2i(target_end), p2i(*target_next));
672 }
673
674 size_t cur_region = addr_to_region_idx(source_beg);
675 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
676
677 HeapWord *dest_addr = target_beg;
678 while (cur_region < end_region) {
679 // The destination must be set even if the region has no data.
680 _region_data[cur_region].set_destination(dest_addr);
681
682 size_t words = _region_data[cur_region].data_size();
683 if (words > 0) {
684 // If cur_region does not fit entirely into the target space, find a point
685 // at which the source space can be 'split' so that part is copied to the
686 // target space and the rest is copied elsewhere.
687 if (dest_addr + words > target_end) {
688 assert(source_next != NULL, "source_next is NULL when splitting");
689 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
690 target_end, target_next);
691 return false;
692 }
693
694 // Compute the destination_count for cur_region, and if necessary, update
695 // source_region for a destination region. The source_region field is
696 // updated if cur_region is the first (left-most) region to be copied to a
697 // destination region.
698 //
699 // The destination_count calculation is a bit subtle. A region that has
700 // data that compacts into itself does not count itself as a destination.
701 // This maintains the invariant that a zero count means the region is
702 // available and can be claimed and then filled.
703 uint destination_count = 0;
704 if (split_info.is_split(cur_region)) {
705 // The current region has been split: the partial object will be copied
706 // to one destination space and the remaining data will be copied to
707 // another destination space. Adjust the initial destination_count and,
708 // if necessary, set the source_region field if the partial object will
709 // cross a destination region boundary.
710 destination_count = split_info.destination_count();
711 if (destination_count == 2) {
712 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
713 _region_data[dest_idx].set_source_region(cur_region);
714 }
715 }
716
717 HeapWord* const last_addr = dest_addr + words - 1;
718 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
719 const size_t dest_region_2 = addr_to_region_idx(last_addr);
720
721 // Initially assume that the destination regions will be the same and
722 // adjust the value below if necessary. Under this assumption, if
723 // cur_region == dest_region_2, then cur_region will be compacted
724 // completely into itself.
725 destination_count += cur_region == dest_region_2 ? 0 : 1;
726 if (dest_region_1 != dest_region_2) {
727 // Destination regions differ; adjust destination_count.
728 destination_count += 1;
729 // Data from cur_region will be copied to the start of dest_region_2.
730 _region_data[dest_region_2].set_source_region(cur_region);
731 } else if (region_offset(dest_addr) == 0) {
732 // Data from cur_region will be copied to the start of the destination
733 // region.
734 _region_data[dest_region_1].set_source_region(cur_region);
735 }
736
737 _region_data[cur_region].set_destination_count(destination_count);
738 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
739 dest_addr += words;
740 }
741
742 ++cur_region;
743 }
744
745 *target_next = dest_addr;
746 return true;
747 }
748
749 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
750 assert(addr != NULL, "Should detect NULL oop earlier");
751 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
752 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
753
754 // Region covering the object.
755 RegionData* const region_ptr = addr_to_region_ptr(addr);
756 HeapWord* result = region_ptr->destination();
757
758 // If the entire Region is live, the new location is region->destination + the
759 // offset of the object within in the Region.
760
761 // Run some performance tests to determine if this special case pays off. It
762 // is worth it for pointers into the dense prefix. If the optimization to
763 // avoid pointer updates in regions that only point to the dense prefix is
764 // ever implemented, this should be revisited.
765 if (region_ptr->data_size() == RegionSize) {
766 result += region_offset(addr);
767 return result;
768 }
769
770 // Otherwise, the new location is region->destination + block offset + the
771 // number of live words in the Block that are (a) to the left of addr and (b)
772 // due to objects that start in the Block.
773
774 // Fill in the block table if necessary. This is unsynchronized, so multiple
775 // threads may fill the block table for a region (harmless, since it is
776 // idempotent).
777 if (!region_ptr->blocks_filled()) {
778 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
779 region_ptr->set_blocks_filled();
780 }
781
782 HeapWord* const search_start = block_align_down(addr);
783 const size_t block_offset = addr_to_block_ptr(addr)->offset();
784
785 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
786 const size_t live = bitmap->live_words_in_range(search_start, oop(addr));
787 result += block_offset + live;
788 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
789 return result;
790 }
791
792 #ifdef ASSERT
793 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
794 {
795 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
796 const size_t* const end = (const size_t*)vspace->committed_high_addr();
797 for (const size_t* p = beg; p < end; ++p) {
798 assert(*p == 0, "not zero");
799 }
800 }
801
802 void ParallelCompactData::verify_clear()
803 {
804 verify_clear(_region_vspace);
805 verify_clear(_block_vspace);
806 }
807 #endif // #ifdef ASSERT
808
809 STWGCTimer PSParallelCompact::_gc_timer;
810 ParallelOldTracer PSParallelCompact::_gc_tracer;
811 elapsedTimer PSParallelCompact::_accumulated_time;
812 unsigned int PSParallelCompact::_total_invocations = 0;
813 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
814 jlong PSParallelCompact::_time_of_last_gc = 0;
815 CollectorCounters* PSParallelCompact::_counters = NULL;
816 ParMarkBitMap PSParallelCompact::_mark_bitmap;
817 ParallelCompactData PSParallelCompact::_summary_data;
818
819 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
820
821 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
822
823 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
824 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
825
826 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure;
827 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
828
829 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
830
831 void PSParallelCompact::FollowKlassClosure::do_klass(Klass* klass) {
832 klass->oops_do(_mark_and_push_closure);
833 }
834 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
835 klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
836 }
837
838 void PSParallelCompact::post_initialize() {
839 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
840 MemRegion mr = heap->reserved_region();
841 _ref_processor =
842 new ReferenceProcessor(mr, // span
843 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
844 (int) ParallelGCThreads, // mt processing degree
845 true, // mt discovery
846 (int) ParallelGCThreads, // mt discovery degree
847 true, // atomic_discovery
848 &_is_alive_closure); // non-header is alive closure
849 _counters = new CollectorCounters("PSParallelCompact", 1);
850
851 // Initialize static fields in ParCompactionManager.
852 ParCompactionManager::initialize(mark_bitmap());
853 }
854
855 bool PSParallelCompact::initialize() {
856 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
857 MemRegion mr = heap->reserved_region();
858
859 // Was the old gen get allocated successfully?
860 if (!heap->old_gen()->is_allocated()) {
861 return false;
862 }
863
864 initialize_space_info();
865 initialize_dead_wood_limiter();
866
867 if (!_mark_bitmap.initialize(mr)) {
868 vm_shutdown_during_initialization(
869 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
870 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
871 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
872 return false;
873 }
874
875 if (!_summary_data.initialize(mr)) {
876 vm_shutdown_during_initialization(
877 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
878 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
879 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
880 return false;
881 }
882
883 return true;
884 }
885
886 void PSParallelCompact::initialize_space_info()
887 {
888 memset(&_space_info, 0, sizeof(_space_info));
889
890 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
891 PSYoungGen* young_gen = heap->young_gen();
892
893 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
894 _space_info[eden_space_id].set_space(young_gen->eden_space());
895 _space_info[from_space_id].set_space(young_gen->from_space());
896 _space_info[to_space_id].set_space(young_gen->to_space());
897
898 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
899 }
900
901 void PSParallelCompact::initialize_dead_wood_limiter()
902 {
903 const size_t max = 100;
904 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
905 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
906 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
907 DEBUG_ONLY(_dwl_initialized = true;)
908 _dwl_adjustment = normal_distribution(1.0);
909 }
910
911 // Simple class for storing info about the heap at the start of GC, to be used
912 // after GC for comparison/printing.
913 class PreGCValues {
914 public:
915 PreGCValues() { }
916 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
917
918 void fill(ParallelScavengeHeap* heap) {
919 _heap_used = heap->used();
920 _young_gen_used = heap->young_gen()->used_in_bytes();
921 _old_gen_used = heap->old_gen()->used_in_bytes();
922 _metadata_used = MetaspaceAux::used_bytes();
923 };
924
925 size_t heap_used() const { return _heap_used; }
926 size_t young_gen_used() const { return _young_gen_used; }
927 size_t old_gen_used() const { return _old_gen_used; }
928 size_t metadata_used() const { return _metadata_used; }
929
930 private:
931 size_t _heap_used;
932 size_t _young_gen_used;
933 size_t _old_gen_used;
934 size_t _metadata_used;
935 };
936
937 void
938 PSParallelCompact::clear_data_covering_space(SpaceId id)
939 {
940 // At this point, top is the value before GC, new_top() is the value that will
941 // be set at the end of GC. The marking bitmap is cleared to top; nothing
942 // should be marked above top. The summary data is cleared to the larger of
943 // top & new_top.
944 MutableSpace* const space = _space_info[id].space();
945 HeapWord* const bot = space->bottom();
946 HeapWord* const top = space->top();
947 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
948
949 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
950 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
951 _mark_bitmap.clear_range(beg_bit, end_bit);
952
953 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
954 const size_t end_region =
955 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
956 _summary_data.clear_range(beg_region, end_region);
957
958 // Clear the data used to 'split' regions.
959 SplitInfo& split_info = _space_info[id].split_info();
960 if (split_info.is_valid()) {
961 split_info.clear();
962 }
963 DEBUG_ONLY(split_info.verify_clear();)
964 }
965
966 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
967 {
968 // Update the from & to space pointers in space_info, since they are swapped
969 // at each young gen gc. Do the update unconditionally (even though a
970 // promotion failure does not swap spaces) because an unknown number of minor
971 // collections will have swapped the spaces an unknown number of times.
972 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
973 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
974 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
975 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
976
977 pre_gc_values->fill(heap);
978
979 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
980 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
981
982 // Increment the invocation count
983 heap->increment_total_collections(true);
984
985 // We need to track unique mark sweep invocations as well.
986 _total_invocations++;
987
988 heap->print_heap_before_gc();
989 heap->trace_heap_before_gc(&_gc_tracer);
990
991 // Fill in TLABs
992 heap->accumulate_statistics_all_tlabs();
993 heap->ensure_parsability(true); // retire TLABs
994
995 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
996 HandleMark hm; // Discard invalid handles created during verification
997 Universe::verify(" VerifyBeforeGC:");
998 }
999
1000 // Verify object start arrays
1001 if (VerifyObjectStartArray &&
1002 VerifyBeforeGC) {
1003 heap->old_gen()->verify_object_start_array();
1004 }
1005
1006 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1007 DEBUG_ONLY(summary_data().verify_clear();)
1008
1009 // Have worker threads release resources the next time they run a task.
1010 gc_task_manager()->release_all_resources();
1011 }
1012
1013 void PSParallelCompact::post_compact()
1014 {
1015 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
1016
1017 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1018 // Clear the marking bitmap, summary data and split info.
1019 clear_data_covering_space(SpaceId(id));
1020 // Update top(). Must be done after clearing the bitmap and summary data.
1021 _space_info[id].publish_new_top();
1022 }
1023
1024 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1025 MutableSpace* const from_space = _space_info[from_space_id].space();
1026 MutableSpace* const to_space = _space_info[to_space_id].space();
1027
1028 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1029 bool eden_empty = eden_space->is_empty();
1030 if (!eden_empty) {
1031 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1032 heap->young_gen(), heap->old_gen());
1033 }
1034
1035 // Update heap occupancy information which is used as input to the soft ref
1036 // clearing policy at the next gc.
1037 Universe::update_heap_info_at_gc();
1038
1039 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1040 to_space->is_empty();
1041
1042 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1043 MemRegion old_mr = heap->old_gen()->reserved();
1044 if (young_gen_empty) {
1045 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1046 } else {
1047 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1048 }
1049
1050 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1051 ClassLoaderDataGraph::purge();
1052 MetaspaceAux::verify_metrics();
1053
1054 CodeCache::gc_epilogue();
1055 JvmtiExport::gc_epilogue();
1056
1057 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1058
1059 ref_processor()->enqueue_discovered_references(NULL);
1060
1061 if (ZapUnusedHeapArea) {
1062 heap->gen_mangle_unused_area();
1063 }
1064
1065 // Update time of last GC
1066 reset_millis_since_last_gc();
1067 }
1068
1069 HeapWord*
1070 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1071 bool maximum_compaction)
1072 {
1073 const size_t region_size = ParallelCompactData::RegionSize;
1074 const ParallelCompactData& sd = summary_data();
1075
1076 const MutableSpace* const space = _space_info[id].space();
1077 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1078 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1079 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1080
1081 // Skip full regions at the beginning of the space--they are necessarily part
1082 // of the dense prefix.
1083 size_t full_count = 0;
1084 const RegionData* cp;
1085 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1086 ++full_count;
1087 }
1088
1089 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1090 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1091 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1092 if (maximum_compaction || cp == end_cp || interval_ended) {
1093 _maximum_compaction_gc_num = total_invocations();
1094 return sd.region_to_addr(cp);
1095 }
1096
1097 HeapWord* const new_top = _space_info[id].new_top();
1098 const size_t space_live = pointer_delta(new_top, space->bottom());
1099 const size_t space_used = space->used_in_words();
1100 const size_t space_capacity = space->capacity_in_words();
1101
1102 const double cur_density = double(space_live) / space_capacity;
1103 const double deadwood_density =
1104 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1105 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1106
1107 if (TraceParallelOldGCDensePrefix) {
1108 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1109 cur_density, deadwood_density, deadwood_goal);
1110 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1111 "space_cap=" SIZE_FORMAT,
1112 space_live, space_used,
1113 space_capacity);
1114 }
1115
1116 // XXX - Use binary search?
1117 HeapWord* dense_prefix = sd.region_to_addr(cp);
1118 const RegionData* full_cp = cp;
1119 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1120 while (cp < end_cp) {
1121 HeapWord* region_destination = cp->destination();
1122 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1123 if (TraceParallelOldGCDensePrefix && Verbose) {
1124 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1125 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1126 sd.region(cp), p2i(region_destination),
1127 p2i(dense_prefix), cur_deadwood);
1128 }
1129
1130 if (cur_deadwood >= deadwood_goal) {
1131 // Found the region that has the correct amount of deadwood to the left.
1132 // This typically occurs after crossing a fairly sparse set of regions, so
1133 // iterate backwards over those sparse regions, looking for the region
1134 // that has the lowest density of live objects 'to the right.'
1135 size_t space_to_left = sd.region(cp) * region_size;
1136 size_t live_to_left = space_to_left - cur_deadwood;
1137 size_t space_to_right = space_capacity - space_to_left;
1138 size_t live_to_right = space_live - live_to_left;
1139 double density_to_right = double(live_to_right) / space_to_right;
1140 while (cp > full_cp) {
1141 --cp;
1142 const size_t prev_region_live_to_right = live_to_right -
1143 cp->data_size();
1144 const size_t prev_region_space_to_right = space_to_right + region_size;
1145 double prev_region_density_to_right =
1146 double(prev_region_live_to_right) / prev_region_space_to_right;
1147 if (density_to_right <= prev_region_density_to_right) {
1148 return dense_prefix;
1149 }
1150 if (TraceParallelOldGCDensePrefix && Verbose) {
1151 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1152 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1153 prev_region_density_to_right);
1154 }
1155 dense_prefix -= region_size;
1156 live_to_right = prev_region_live_to_right;
1157 space_to_right = prev_region_space_to_right;
1158 density_to_right = prev_region_density_to_right;
1159 }
1160 return dense_prefix;
1161 }
1162
1163 dense_prefix += region_size;
1164 ++cp;
1165 }
1166
1167 return dense_prefix;
1168 }
1169
1170 #ifndef PRODUCT
1171 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1172 const SpaceId id,
1173 const bool maximum_compaction,
1174 HeapWord* const addr)
1175 {
1176 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1177 RegionData* const cp = summary_data().region(region_idx);
1178 const MutableSpace* const space = _space_info[id].space();
1179 HeapWord* const new_top = _space_info[id].new_top();
1180
1181 const size_t space_live = pointer_delta(new_top, space->bottom());
1182 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1183 const size_t space_cap = space->capacity_in_words();
1184 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1185 const size_t live_to_right = new_top - cp->destination();
1186 const size_t dead_to_right = space->top() - addr - live_to_right;
1187
1188 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1189 "spl=" SIZE_FORMAT " "
1190 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1191 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1192 " ratio=%10.8f",
1193 algorithm, p2i(addr), region_idx,
1194 space_live,
1195 dead_to_left, dead_to_left_pct,
1196 dead_to_right, live_to_right,
1197 double(dead_to_right) / live_to_right);
1198 }
1199 #endif // #ifndef PRODUCT
1200
1201 // Return a fraction indicating how much of the generation can be treated as
1202 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1203 // based on the density of live objects in the generation to determine a limit,
1204 // which is then adjusted so the return value is min_percent when the density is
1205 // 1.
1206 //
1207 // The following table shows some return values for a different values of the
1208 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1209 // min_percent is 1.
1210 //
1211 // fraction allowed as dead wood
1212 // -----------------------------------------------------------------
1213 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1214 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1215 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1216 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1217 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1218 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1219 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1220 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1221 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1222 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1223 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1224 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1225 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1226 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1227 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1228 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1229 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1230 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1231 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1232 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1233 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1234 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1235 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1236
1237 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1238 {
1239 assert(_dwl_initialized, "uninitialized");
1240
1241 // The raw limit is the value of the normal distribution at x = density.
1242 const double raw_limit = normal_distribution(density);
1243
1244 // Adjust the raw limit so it becomes the minimum when the density is 1.
1245 //
1246 // First subtract the adjustment value (which is simply the precomputed value
1247 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1248 // Then add the minimum value, so the minimum is returned when the density is
1249 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1250 const double min = double(min_percent) / 100.0;
1251 const double limit = raw_limit - _dwl_adjustment + min;
1252 return MAX2(limit, 0.0);
1253 }
1254
1255 ParallelCompactData::RegionData*
1256 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1257 const RegionData* end)
1258 {
1259 const size_t region_size = ParallelCompactData::RegionSize;
1260 ParallelCompactData& sd = summary_data();
1261 size_t left = sd.region(beg);
1262 size_t right = end > beg ? sd.region(end) - 1 : left;
1263
1264 // Binary search.
1265 while (left < right) {
1266 // Equivalent to (left + right) / 2, but does not overflow.
1267 const size_t middle = left + (right - left) / 2;
1268 RegionData* const middle_ptr = sd.region(middle);
1269 HeapWord* const dest = middle_ptr->destination();
1270 HeapWord* const addr = sd.region_to_addr(middle);
1271 assert(dest != NULL, "sanity");
1272 assert(dest <= addr, "must move left");
1273
1274 if (middle > left && dest < addr) {
1275 right = middle - 1;
1276 } else if (middle < right && middle_ptr->data_size() == region_size) {
1277 left = middle + 1;
1278 } else {
1279 return middle_ptr;
1280 }
1281 }
1282 return sd.region(left);
1283 }
1284
1285 ParallelCompactData::RegionData*
1286 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1287 const RegionData* end,
1288 size_t dead_words)
1289 {
1290 ParallelCompactData& sd = summary_data();
1291 size_t left = sd.region(beg);
1292 size_t right = end > beg ? sd.region(end) - 1 : left;
1293
1294 // Binary search.
1295 while (left < right) {
1296 // Equivalent to (left + right) / 2, but does not overflow.
1297 const size_t middle = left + (right - left) / 2;
1298 RegionData* const middle_ptr = sd.region(middle);
1299 HeapWord* const dest = middle_ptr->destination();
1300 HeapWord* const addr = sd.region_to_addr(middle);
1301 assert(dest != NULL, "sanity");
1302 assert(dest <= addr, "must move left");
1303
1304 const size_t dead_to_left = pointer_delta(addr, dest);
1305 if (middle > left && dead_to_left > dead_words) {
1306 right = middle - 1;
1307 } else if (middle < right && dead_to_left < dead_words) {
1308 left = middle + 1;
1309 } else {
1310 return middle_ptr;
1311 }
1312 }
1313 return sd.region(left);
1314 }
1315
1316 // The result is valid during the summary phase, after the initial summarization
1317 // of each space into itself, and before final summarization.
1318 inline double
1319 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1320 HeapWord* const bottom,
1321 HeapWord* const top,
1322 HeapWord* const new_top)
1323 {
1324 ParallelCompactData& sd = summary_data();
1325
1326 assert(cp != NULL, "sanity");
1327 assert(bottom != NULL, "sanity");
1328 assert(top != NULL, "sanity");
1329 assert(new_top != NULL, "sanity");
1330 assert(top >= new_top, "summary data problem?");
1331 assert(new_top > bottom, "space is empty; should not be here");
1332 assert(new_top >= cp->destination(), "sanity");
1333 assert(top >= sd.region_to_addr(cp), "sanity");
1334
1335 HeapWord* const destination = cp->destination();
1336 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1337 const size_t compacted_region_live = pointer_delta(new_top, destination);
1338 const size_t compacted_region_used = pointer_delta(top,
1339 sd.region_to_addr(cp));
1340 const size_t reclaimable = compacted_region_used - compacted_region_live;
1341
1342 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1343 return double(reclaimable) / divisor;
1344 }
1345
1346 // Return the address of the end of the dense prefix, a.k.a. the start of the
1347 // compacted region. The address is always on a region boundary.
1348 //
1349 // Completely full regions at the left are skipped, since no compaction can
1350 // occur in those regions. Then the maximum amount of dead wood to allow is
1351 // computed, based on the density (amount live / capacity) of the generation;
1352 // the region with approximately that amount of dead space to the left is
1353 // identified as the limit region. Regions between the last completely full
1354 // region and the limit region are scanned and the one that has the best
1355 // (maximum) reclaimed_ratio() is selected.
1356 HeapWord*
1357 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1358 bool maximum_compaction)
1359 {
1360 if (ParallelOldGCSplitALot) {
1361 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1362 // The value was chosen to provoke splitting a young gen space; use it.
1363 return _space_info[id].dense_prefix();
1364 }
1365 }
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 #if 0
1440 // Something to consider: if the region with the best ratio is 'close to' the
1441 // first region w/free space, choose the first region with free space
1442 // ("first-free"). The first-free region is usually near the start of the
1443 // heap, which means we are copying most of the heap already, so copy a bit
1444 // more to get complete compaction.
1445 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1446 _maximum_compaction_gc_num = total_invocations();
1447 best_cp = full_cp;
1448 }
1449 #endif // #if 0
1450
1451 return sd.region_to_addr(best_cp);
1452 }
1453
1454 #ifndef PRODUCT
1455 void
1456 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1457 size_t words)
1458 {
1459 if (TraceParallelOldGCSummaryPhase) {
1460 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1461 SIZE_FORMAT, p2i(start), p2i(start + words), words);
1462 }
1463
1464 ObjectStartArray* const start_array = _space_info[id].start_array();
1465 CollectedHeap::fill_with_objects(start, words);
1466 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1467 _mark_bitmap.mark_obj(p, words);
1468 _summary_data.add_obj(p, words);
1469 start_array->allocate_block(p);
1470 }
1471 }
1472
1473 void
1474 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1475 {
1476 ParallelCompactData& sd = summary_data();
1477 MutableSpace* space = _space_info[id].space();
1478
1479 // Find the source and destination start addresses.
1480 HeapWord* const src_addr = sd.region_align_down(start);
1481 HeapWord* dst_addr;
1482 if (src_addr < start) {
1483 dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1484 } else if (src_addr > space->bottom()) {
1485 // The start (the original top() value) is aligned to a region boundary so
1486 // the associated region does not have a destination. Compute the
1487 // destination from the previous region.
1488 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1489 dst_addr = cp->destination() + cp->data_size();
1490 } else {
1491 // Filling the entire space.
1492 dst_addr = space->bottom();
1493 }
1494 assert(dst_addr != NULL, "sanity");
1495
1496 // Update the summary data.
1497 bool result = _summary_data.summarize(_space_info[id].split_info(),
1498 src_addr, space->top(), NULL,
1499 dst_addr, space->end(),
1500 _space_info[id].new_top_addr());
1501 assert(result, "should not fail: bad filler object size");
1502 }
1503
1504 void
1505 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1506 {
1507 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1508 return;
1509 }
1510
1511 MutableSpace* const space = _space_info[id].space();
1512 if (space->is_empty()) {
1513 HeapWord* b = space->bottom();
1514 HeapWord* t = b + space->capacity_in_words() / 2;
1515 space->set_top(t);
1516 if (ZapUnusedHeapArea) {
1517 space->set_top_for_allocations();
1518 }
1519
1520 size_t min_size = CollectedHeap::min_fill_size();
1521 size_t obj_len = min_size;
1522 while (b + obj_len <= t) {
1523 CollectedHeap::fill_with_object(b, obj_len);
1524 mark_bitmap()->mark_obj(b, obj_len);
1525 summary_data().add_obj(b, obj_len);
1526 b += obj_len;
1527 obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1528 }
1529 if (b < t) {
1530 // The loop didn't completely fill to t (top); adjust top downward.
1531 space->set_top(b);
1532 if (ZapUnusedHeapArea) {
1533 space->set_top_for_allocations();
1534 }
1535 }
1536
1537 HeapWord** nta = _space_info[id].new_top_addr();
1538 bool result = summary_data().summarize(_space_info[id].split_info(),
1539 space->bottom(), space->top(), NULL,
1540 space->bottom(), space->end(), nta);
1541 assert(result, "space must fit into itself");
1542 }
1543 }
1544
1545 void
1546 PSParallelCompact::provoke_split(bool & max_compaction)
1547 {
1548 if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1549 return;
1550 }
1551
1552 const size_t region_size = ParallelCompactData::RegionSize;
1553 ParallelCompactData& sd = summary_data();
1554
1555 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1556 MutableSpace* const from_space = _space_info[from_space_id].space();
1557 const size_t eden_live = pointer_delta(eden_space->top(),
1558 _space_info[eden_space_id].new_top());
1559 const size_t from_live = pointer_delta(from_space->top(),
1560 _space_info[from_space_id].new_top());
1561
1562 const size_t min_fill_size = CollectedHeap::min_fill_size();
1563 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1564 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1565 const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1566 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1567
1568 // Choose the space to split; need at least 2 regions live (or fillable).
1569 SpaceId id;
1570 MutableSpace* space;
1571 size_t live_words;
1572 size_t fill_words;
1573 if (eden_live + eden_fillable >= region_size * 2) {
1574 id = eden_space_id;
1575 space = eden_space;
1576 live_words = eden_live;
1577 fill_words = eden_fillable;
1578 } else if (from_live + from_fillable >= region_size * 2) {
1579 id = from_space_id;
1580 space = from_space;
1581 live_words = from_live;
1582 fill_words = from_fillable;
1583 } else {
1584 return; // Give up.
1585 }
1586 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1587
1588 if (live_words < region_size * 2) {
1589 // Fill from top() to end() w/live objects of mixed sizes.
1590 HeapWord* const fill_start = space->top();
1591 live_words += fill_words;
1592
1593 space->set_top(fill_start + fill_words);
1594 if (ZapUnusedHeapArea) {
1595 space->set_top_for_allocations();
1596 }
1597
1598 HeapWord* cur_addr = fill_start;
1599 while (fill_words > 0) {
1600 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1601 size_t cur_size = MIN2(align_object_size_(r), fill_words);
1602 if (fill_words - cur_size < min_fill_size) {
1603 cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1604 }
1605
1606 CollectedHeap::fill_with_object(cur_addr, cur_size);
1607 mark_bitmap()->mark_obj(cur_addr, cur_size);
1608 sd.add_obj(cur_addr, cur_size);
1609
1610 cur_addr += cur_size;
1611 fill_words -= cur_size;
1612 }
1613
1614 summarize_new_objects(id, fill_start);
1615 }
1616
1617 max_compaction = false;
1618
1619 // Manipulate the old gen so that it has room for about half of the live data
1620 // in the target young gen space (live_words / 2).
1621 id = old_space_id;
1622 space = _space_info[id].space();
1623 const size_t free_at_end = space->free_in_words();
1624 const size_t free_target = align_object_size(live_words / 2);
1625 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1626
1627 if (free_at_end >= free_target + min_fill_size) {
1628 // Fill space above top() and set the dense prefix so everything survives.
1629 HeapWord* const fill_start = space->top();
1630 const size_t fill_size = free_at_end - free_target;
1631 space->set_top(space->top() + fill_size);
1632 if (ZapUnusedHeapArea) {
1633 space->set_top_for_allocations();
1634 }
1635 fill_with_live_objects(id, fill_start, fill_size);
1636 summarize_new_objects(id, fill_start);
1637 _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1638 } else if (dead + free_at_end > free_target) {
1639 // Find a dense prefix that makes the right amount of space available.
1640 HeapWord* cur = sd.region_align_down(space->top());
1641 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1642 size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1643 while (dead_to_right < free_target) {
1644 cur -= region_size;
1645 cur_destination = sd.addr_to_region_ptr(cur)->destination();
1646 dead_to_right = pointer_delta(space->end(), cur_destination);
1647 }
1648 _space_info[id].set_dense_prefix(cur);
1649 }
1650 }
1651 #endif // #ifndef PRODUCT
1652
1653 void PSParallelCompact::summarize_spaces_quick()
1654 {
1655 for (unsigned int i = 0; i < last_space_id; ++i) {
1656 const MutableSpace* space = _space_info[i].space();
1657 HeapWord** nta = _space_info[i].new_top_addr();
1658 bool result = _summary_data.summarize(_space_info[i].split_info(),
1659 space->bottom(), space->top(), NULL,
1660 space->bottom(), space->end(), nta);
1661 assert(result, "space must fit into itself");
1662 _space_info[i].set_dense_prefix(space->bottom());
1663 }
1664
1665 #ifndef PRODUCT
1666 if (ParallelOldGCSplitALot) {
1667 provoke_split_fill_survivor(to_space_id);
1668 }
1669 #endif // #ifndef PRODUCT
1670 }
1671
1672 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1673 {
1674 HeapWord* const dense_prefix_end = dense_prefix(id);
1675 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1676 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1677 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1678 // Only enough dead space is filled so that any remaining dead space to the
1679 // left is larger than the minimum filler object. (The remainder is filled
1680 // during the copy/update phase.)
1681 //
1682 // The size of the dead space to the right of the boundary is not a
1683 // concern, since compaction will be able to use whatever space is
1684 // available.
1685 //
1686 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1687 // surrounds the space to be filled with an object.
1688 //
1689 // In the 32-bit VM, each bit represents two 32-bit words:
1690 // +---+
1691 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1692 // end_bits: ... x x x | 0 | || 0 x x ...
1693 // +---+
1694 //
1695 // In the 64-bit VM, each bit represents one 64-bit word:
1696 // +------------+
1697 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1698 // end_bits: ... x x 1 | 0 || 0 | x x ...
1699 // +------------+
1700 // +-------+
1701 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1702 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1703 // +-------+
1704 // +-----------+
1705 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1706 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1707 // +-----------+
1708 // +-------+
1709 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1710 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1711 // +-------+
1712
1713 // Initially assume case a, c or e will apply.
1714 size_t obj_len = CollectedHeap::min_fill_size();
1715 HeapWord* obj_beg = dense_prefix_end - obj_len;
1716
1717 #ifdef _LP64
1718 if (MinObjAlignment > 1) { // object alignment > heap word size
1719 // Cases a, c or e.
1720 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1721 // Case b above.
1722 obj_beg = dense_prefix_end - 1;
1723 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1724 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1725 // Case d above.
1726 obj_beg = dense_prefix_end - 3;
1727 obj_len = 3;
1728 }
1729 #endif // #ifdef _LP64
1730
1731 CollectedHeap::fill_with_object(obj_beg, obj_len);
1732 _mark_bitmap.mark_obj(obj_beg, obj_len);
1733 _summary_data.add_obj(obj_beg, obj_len);
1734 assert(start_array(id) != NULL, "sanity");
1735 start_array(id)->allocate_block(obj_beg);
1736 }
1737 }
1738
1739 void
1740 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1741 {
1742 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1743 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1744 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1745 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1746 cur->set_source_region(0);
1747 }
1748 }
1749
1750 void
1751 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1752 {
1753 assert(id < last_space_id, "id out of range");
1754 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1755 ParallelOldGCSplitALot && id == old_space_id,
1756 "should have been reset in summarize_spaces_quick()");
1757
1758 const MutableSpace* space = _space_info[id].space();
1759 if (_space_info[id].new_top() != space->bottom()) {
1760 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1761 _space_info[id].set_dense_prefix(dense_prefix_end);
1762
1763 #ifndef PRODUCT
1764 if (TraceParallelOldGCDensePrefix) {
1765 print_dense_prefix_stats("ratio", id, maximum_compaction,
1766 dense_prefix_end);
1767 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1768 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1769 }
1770 #endif // #ifndef PRODUCT
1771
1772 // Recompute the summary data, taking into account the dense prefix. If
1773 // every last byte will be reclaimed, then the existing summary data which
1774 // compacts everything can be left in place.
1775 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1776 // If dead space crosses the dense prefix boundary, it is (at least
1777 // partially) filled with a dummy object, marked live and added to the
1778 // summary data. This simplifies the copy/update phase and must be done
1779 // before the final locations of objects are determined, to prevent
1780 // leaving a fragment of dead space that is too small to fill.
1781 fill_dense_prefix_end(id);
1782
1783 // Compute the destination of each Region, and thus each object.
1784 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1785 _summary_data.summarize(_space_info[id].split_info(),
1786 dense_prefix_end, space->top(), NULL,
1787 dense_prefix_end, space->end(),
1788 _space_info[id].new_top_addr());
1789 }
1790 }
1791
1792 if (TraceParallelOldGCSummaryPhase) {
1793 const size_t region_size = ParallelCompactData::RegionSize;
1794 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1795 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1796 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1797 HeapWord* const new_top = _space_info[id].new_top();
1798 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1799 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1800 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1801 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1802 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1803 id, space->capacity_in_words(), p2i(dense_prefix_end),
1804 dp_region, dp_words / region_size,
1805 cr_words / region_size, p2i(new_top));
1806 }
1807 }
1808
1809 #ifndef PRODUCT
1810 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1811 HeapWord* dst_beg, HeapWord* dst_end,
1812 SpaceId src_space_id,
1813 HeapWord* src_beg, HeapWord* src_end)
1814 {
1815 if (TraceParallelOldGCSummaryPhase) {
1816 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1817 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1818 SIZE_FORMAT "-" SIZE_FORMAT " "
1819 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1820 SIZE_FORMAT "-" SIZE_FORMAT,
1821 src_space_id, space_names[src_space_id],
1822 dst_space_id, space_names[dst_space_id],
1823 p2i(src_beg), p2i(src_end),
1824 _summary_data.addr_to_region_idx(src_beg),
1825 _summary_data.addr_to_region_idx(src_end),
1826 p2i(dst_beg), p2i(dst_end),
1827 _summary_data.addr_to_region_idx(dst_beg),
1828 _summary_data.addr_to_region_idx(dst_end));
1829 }
1830 }
1831 #endif // #ifndef PRODUCT
1832
1833 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1834 bool maximum_compaction)
1835 {
1836 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
1837 // trace("2");
1838
1839 #ifdef ASSERT
1840 if (TraceParallelOldGCMarkingPhase) {
1841 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1842 "add_obj_bytes=" SIZE_FORMAT,
1843 add_obj_count, add_obj_size * HeapWordSize);
1844 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1845 "mark_bitmap_bytes=" SIZE_FORMAT,
1846 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1847 }
1848 #endif // #ifdef ASSERT
1849
1850 // Quick summarization of each space into itself, to see how much is live.
1851 summarize_spaces_quick();
1852
1853 if (TraceParallelOldGCSummaryPhase) {
1854 tty->print_cr("summary_phase: after summarizing each space to self");
1855 Universe::print();
1856 NOT_PRODUCT(print_region_ranges());
1857 if (Verbose) {
1858 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1859 }
1860 }
1861
1862 // The amount of live data that will end up in old space (assuming it fits).
1863 size_t old_space_total_live = 0;
1864 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1865 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1866 _space_info[id].space()->bottom());
1867 }
1868
1869 MutableSpace* const old_space = _space_info[old_space_id].space();
1870 const size_t old_capacity = old_space->capacity_in_words();
1871 if (old_space_total_live > old_capacity) {
1872 // XXX - should also try to expand
1873 maximum_compaction = true;
1874 }
1875 #ifndef PRODUCT
1876 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1877 provoke_split(maximum_compaction);
1878 }
1879 #endif // #ifndef PRODUCT
1880
1881 // Old generations.
1882 summarize_space(old_space_id, maximum_compaction);
1883
1884 // Summarize the remaining spaces in the young gen. The initial target space
1885 // is the old gen. If a space does not fit entirely into the target, then the
1886 // remainder is compacted into the space itself and that space becomes the new
1887 // target.
1888 SpaceId dst_space_id = old_space_id;
1889 HeapWord* dst_space_end = old_space->end();
1890 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1891 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1892 const MutableSpace* space = _space_info[id].space();
1893 const size_t live = pointer_delta(_space_info[id].new_top(),
1894 space->bottom());
1895 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1896
1897 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1898 SpaceId(id), space->bottom(), space->top());)
1899 if (live > 0 && live <= available) {
1900 // All the live data will fit.
1901 bool done = _summary_data.summarize(_space_info[id].split_info(),
1902 space->bottom(), space->top(),
1903 NULL,
1904 *new_top_addr, dst_space_end,
1905 new_top_addr);
1906 assert(done, "space must fit into old gen");
1907
1908 // Reset the new_top value for the space.
1909 _space_info[id].set_new_top(space->bottom());
1910 } else if (live > 0) {
1911 // Attempt to fit part of the source space into the target space.
1912 HeapWord* next_src_addr = NULL;
1913 bool done = _summary_data.summarize(_space_info[id].split_info(),
1914 space->bottom(), space->top(),
1915 &next_src_addr,
1916 *new_top_addr, dst_space_end,
1917 new_top_addr);
1918 assert(!done, "space should not fit into old gen");
1919 assert(next_src_addr != NULL, "sanity");
1920
1921 // The source space becomes the new target, so the remainder is compacted
1922 // within the space itself.
1923 dst_space_id = SpaceId(id);
1924 dst_space_end = space->end();
1925 new_top_addr = _space_info[id].new_top_addr();
1926 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1927 space->bottom(), dst_space_end,
1928 SpaceId(id), next_src_addr, space->top());)
1929 done = _summary_data.summarize(_space_info[id].split_info(),
1930 next_src_addr, space->top(),
1931 NULL,
1932 space->bottom(), dst_space_end,
1933 new_top_addr);
1934 assert(done, "space must fit when compacted into itself");
1935 assert(*new_top_addr <= space->top(), "usage should not grow");
1936 }
1937 }
1938
1939 if (TraceParallelOldGCSummaryPhase) {
1940 tty->print_cr("summary_phase: after final summarization");
1941 Universe::print();
1942 NOT_PRODUCT(print_region_ranges());
1943 if (Verbose) {
1944 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1945 }
1946 }
1947 }
1948
1949 // This method should contain all heap-specific policy for invoking a full
1950 // collection. invoke_no_policy() will only attempt to compact the heap; it
1951 // will do nothing further. If we need to bail out for policy reasons, scavenge
1952 // before full gc, or any other specialized behavior, it needs to be added here.
1953 //
1954 // Note that this method should only be called from the vm_thread while at a
1955 // safepoint.
1956 //
1957 // Note that the all_soft_refs_clear flag in the collector policy
1958 // may be true because this method can be called without intervening
1959 // activity. For example when the heap space is tight and full measure
1960 // are being taken to free space.
1961 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1962 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1963 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1964 "should be in vm thread");
1965
1966 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1967 GCCause::Cause gc_cause = heap->gc_cause();
1968 assert(!heap->is_gc_active(), "not reentrant");
1969
1970 PSAdaptiveSizePolicy* policy = heap->size_policy();
1971 IsGCActiveMark mark;
1972
1973 if (ScavengeBeforeFullGC) {
1974 PSScavenge::invoke_no_policy();
1975 }
1976
1977 const bool clear_all_soft_refs =
1978 heap->collector_policy()->should_clear_all_soft_refs();
1979
1980 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1981 maximum_heap_compaction);
1982 }
1983
1984 // This method contains no policy. You should probably
1985 // be calling invoke() instead.
1986 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1987 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1988 assert(ref_processor() != NULL, "Sanity");
1989
1990 if (GC_locker::check_active_before_gc()) {
1991 return false;
1992 }
1993
1994 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1995
1996 _gc_timer.register_gc_start();
1997 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1998
1999 TimeStamp marking_start;
2000 TimeStamp compaction_start;
2001 TimeStamp collection_exit;
2002
2003 GCCause::Cause gc_cause = heap->gc_cause();
2004 PSYoungGen* young_gen = heap->young_gen();
2005 PSOldGen* old_gen = heap->old_gen();
2006 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
2007
2008 // The scope of casr should end after code that can change
2009 // CollectorPolicy::_should_clear_all_soft_refs.
2010 ClearedAllSoftRefs casr(maximum_heap_compaction,
2011 heap->collector_policy());
2012
2013 if (ZapUnusedHeapArea) {
2014 // Save information needed to minimize mangling
2015 heap->record_gen_tops_before_GC();
2016 }
2017
2018 heap->pre_full_gc_dump(&_gc_timer);
2019
2020 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
2021
2022 // Make sure data structures are sane, make the heap parsable, and do other
2023 // miscellaneous bookkeeping.
2024 PreGCValues pre_gc_values;
2025 pre_compact(&pre_gc_values);
2026
2027 // Get the compaction manager reserved for the VM thread.
2028 ParCompactionManager* const vmthread_cm =
2029 ParCompactionManager::manager_array(gc_task_manager()->workers());
2030
2031 // Place after pre_compact() where the number of invocations is incremented.
2032 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2033
2034 {
2035 ResourceMark rm;
2036 HandleMark hm;
2037
2038 // Set the number of GC threads to be used in this collection
2039 gc_task_manager()->set_active_gang();
2040 gc_task_manager()->task_idle_workers();
2041 heap->set_par_threads(gc_task_manager()->active_workers());
2042
2043 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2044 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id());
2045 TraceCollectorStats tcs(counters());
2046 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
2047
2048 if (TraceOldGenTime) accumulated_time()->start();
2049
2050 // Let the size policy know we're starting
2051 size_policy->major_collection_begin();
2052
2053 CodeCache::gc_prologue();
2054
2055 COMPILER2_PRESENT(DerivedPointerTable::clear());
2056
2057 ref_processor()->enable_discovery();
2058 ref_processor()->setup_policy(maximum_heap_compaction);
2059
2060 bool marked_for_unloading = false;
2061
2062 marking_start.update();
2063 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
2064
2065 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
2066 && gc_cause == GCCause::_java_lang_system_gc;
2067 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2068
2069 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2070 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2071
2072 // adjust_roots() updates Universe::_intArrayKlassObj which is
2073 // needed by the compaction for filling holes in the dense prefix.
2074 adjust_roots();
2075
2076 compaction_start.update();
2077 compact();
2078
2079 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
2080 // done before resizing.
2081 post_compact();
2082
2083 // Let the size policy know we're done
2084 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2085
2086 if (UseAdaptiveSizePolicy) {
2087 if (PrintAdaptiveSizePolicy) {
2088 gclog_or_tty->print("AdaptiveSizeStart: ");
2089 gclog_or_tty->stamp();
2090 gclog_or_tty->print_cr(" collection: %d ",
2091 heap->total_collections());
2092 if (Verbose) {
2093 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
2094 " young_gen_capacity: " SIZE_FORMAT,
2095 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
2096 }
2097 }
2098
2099 // Don't check if the size_policy is ready here. Let
2100 // the size_policy check that internally.
2101 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2102 ((gc_cause != GCCause::_java_lang_system_gc) ||
2103 UseAdaptiveSizePolicyWithSystemGC)) {
2104 // Swap the survivor spaces if from_space is empty. The
2105 // resize_young_gen() called below is normally used after
2106 // a successful young GC and swapping of survivor spaces;
2107 // otherwise, it will fail to resize the young gen with
2108 // the current implementation.
2109 if (young_gen->from_space()->is_empty()) {
2110 young_gen->from_space()->clear(SpaceDecorator::Mangle);
2111 young_gen->swap_spaces();
2112 }
2113
2114 // Calculate optimal free space amounts
2115 assert(young_gen->max_size() >
2116 young_gen->from_space()->capacity_in_bytes() +
2117 young_gen->to_space()->capacity_in_bytes(),
2118 "Sizes of space in young gen are out-of-bounds");
2119
2120 size_t young_live = young_gen->used_in_bytes();
2121 size_t eden_live = young_gen->eden_space()->used_in_bytes();
2122 size_t old_live = old_gen->used_in_bytes();
2123 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
2124 size_t max_old_gen_size = old_gen->max_gen_size();
2125 size_t max_eden_size = young_gen->max_size() -
2126 young_gen->from_space()->capacity_in_bytes() -
2127 young_gen->to_space()->capacity_in_bytes();
2128
2129 // Used for diagnostics
2130 size_policy->clear_generation_free_space_flags();
2131
2132 size_policy->compute_generations_free_space(young_live,
2133 eden_live,
2134 old_live,
2135 cur_eden,
2136 max_old_gen_size,
2137 max_eden_size,
2138 true /* full gc*/);
2139
2140 size_policy->check_gc_overhead_limit(young_live,
2141 eden_live,
2142 max_old_gen_size,
2143 max_eden_size,
2144 true /* full gc*/,
2145 gc_cause,
2146 heap->collector_policy());
2147
2148 size_policy->decay_supplemental_growth(true /* full gc*/);
2149
2150 heap->resize_old_gen(
2151 size_policy->calculated_old_free_size_in_bytes());
2152
2153 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
2154 size_policy->calculated_survivor_size_in_bytes());
2155 }
2156 if (PrintAdaptiveSizePolicy) {
2157 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2158 heap->total_collections());
2159 }
2160 }
2161
2162 if (UsePerfData) {
2163 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2164 counters->update_counters();
2165 counters->update_old_capacity(old_gen->capacity_in_bytes());
2166 counters->update_young_capacity(young_gen->capacity_in_bytes());
2167 }
2168
2169 heap->resize_all_tlabs();
2170
2171 // Resize the metaspace capacity after a collection
2172 MetaspaceGC::compute_new_size();
2173
2174 if (TraceOldGenTime) accumulated_time()->stop();
2175
2176 if (PrintGC) {
2177 if (PrintGCDetails) {
2178 // No GC timestamp here. This is after GC so it would be confusing.
2179 young_gen->print_used_change(pre_gc_values.young_gen_used());
2180 old_gen->print_used_change(pre_gc_values.old_gen_used());
2181 heap->print_heap_change(pre_gc_values.heap_used());
2182 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
2183 } else {
2184 heap->print_heap_change(pre_gc_values.heap_used());
2185 }
2186 }
2187
2188 // Track memory usage and detect low memory
2189 MemoryService::track_memory_usage();
2190 heap->update_counters();
2191 gc_task_manager()->release_idle_workers();
2192 }
2193
2194 #ifdef ASSERT
2195 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
2196 ParCompactionManager* const cm =
2197 ParCompactionManager::manager_array(int(i));
2198 assert(cm->marking_stack()->is_empty(), "should be empty");
2199 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
2200 }
2201 #endif // ASSERT
2202
2203 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2204 HandleMark hm; // Discard invalid handles created during verification
2205 Universe::verify(" VerifyAfterGC:");
2206 }
2207
2208 // Re-verify object start arrays
2209 if (VerifyObjectStartArray &&
2210 VerifyAfterGC) {
2211 old_gen->verify_object_start_array();
2212 }
2213
2214 if (ZapUnusedHeapArea) {
2215 old_gen->object_space()->check_mangled_unused_area_complete();
2216 }
2217
2218 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2219
2220 collection_exit.update();
2221
2222 heap->print_heap_after_gc();
2223 heap->trace_heap_after_gc(&_gc_tracer);
2224
2225 if (PrintGCTaskTimeStamps) {
2226 gclog_or_tty->print_cr("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " "
2227 JLONG_FORMAT,
2228 marking_start.ticks(), compaction_start.ticks(),
2229 collection_exit.ticks());
2230 gc_task_manager()->print_task_time_stamps();
2231 }
2232
2233 heap->post_full_gc_dump(&_gc_timer);
2234
2235 #ifdef TRACESPINNING
2236 ParallelTaskTerminator::print_termination_counts();
2237 #endif
2238
2239 _gc_timer.register_gc_end();
2240
2241 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
2242 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
2243
2244 return true;
2245 }
2246
2247 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2248 PSYoungGen* young_gen,
2249 PSOldGen* old_gen) {
2250 MutableSpace* const eden_space = young_gen->eden_space();
2251 assert(!eden_space->is_empty(), "eden must be non-empty");
2252 assert(young_gen->virtual_space()->alignment() ==
2253 old_gen->virtual_space()->alignment(), "alignments do not match");
2254
2255 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2256 return false;
2257 }
2258
2259 // Both generations must be completely committed.
2260 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2261 return false;
2262 }
2263 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2264 return false;
2265 }
2266
2267 // Figure out how much to take from eden. Include the average amount promoted
2268 // in the total; otherwise the next young gen GC will simply bail out to a
2269 // full GC.
2270 const size_t alignment = old_gen->virtual_space()->alignment();
2271 const size_t eden_used = eden_space->used_in_bytes();
2272 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2273 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2274 const size_t eden_capacity = eden_space->capacity_in_bytes();
2275
2276 if (absorb_size >= eden_capacity) {
2277 return false; // Must leave some space in eden.
2278 }
2279
2280 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2281 if (new_young_size < young_gen->min_gen_size()) {
2282 return false; // Respect young gen minimum size.
2283 }
2284
2285 if (TraceAdaptiveGCBoundary && Verbose) {
2286 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2287 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2288 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2289 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2290 absorb_size / K,
2291 eden_capacity / K, (eden_capacity - absorb_size) / K,
2292 young_gen->from_space()->used_in_bytes() / K,
2293 young_gen->to_space()->used_in_bytes() / K,
2294 young_gen->capacity_in_bytes() / K, new_young_size / K);
2295 }
2296
2297 // Fill the unused part of the old gen.
2298 MutableSpace* const old_space = old_gen->object_space();
2299 HeapWord* const unused_start = old_space->top();
2300 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2301
2302 if (unused_words > 0) {
2303 if (unused_words < CollectedHeap::min_fill_size()) {
2304 return false; // If the old gen cannot be filled, must give up.
2305 }
2306 CollectedHeap::fill_with_objects(unused_start, unused_words);
2307 }
2308
2309 // Take the live data from eden and set both top and end in the old gen to
2310 // eden top. (Need to set end because reset_after_change() mangles the region
2311 // from end to virtual_space->high() in debug builds).
2312 HeapWord* const new_top = eden_space->top();
2313 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2314 absorb_size);
2315 young_gen->reset_after_change();
2316 old_space->set_top(new_top);
2317 old_space->set_end(new_top);
2318 old_gen->reset_after_change();
2319
2320 // Update the object start array for the filler object and the data from eden.
2321 ObjectStartArray* const start_array = old_gen->start_array();
2322 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2323 start_array->allocate_block(p);
2324 }
2325
2326 // Could update the promoted average here, but it is not typically updated at
2327 // full GCs and the value to use is unclear. Something like
2328 //
2329 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2330
2331 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2332 return true;
2333 }
2334
2335 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2336 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2337 "shouldn't return NULL");
2338 return ParallelScavengeHeap::gc_task_manager();
2339 }
2340
2341 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2342 bool maximum_heap_compaction,
2343 ParallelOldTracer *gc_tracer) {
2344 // Recursively traverse all live objects and mark them
2345 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2346
2347 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2348 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2349 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2350 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2351 ParallelTaskTerminator terminator(active_gc_threads, qset);
2352
2353 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2354 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2355
2356 // Need new claim bits before marking starts.
2357 ClassLoaderDataGraph::clear_claimed_marks();
2358
2359 {
2360 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2361
2362 ParallelScavengeHeap::ParStrongRootsScope psrs;
2363
2364 GCTaskQueue* q = GCTaskQueue::create();
2365
2366 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2367 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2368 // We scan the thread roots in parallel
2369 Threads::create_thread_roots_marking_tasks(q);
2370 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2371 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2372 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2373 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2374 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2375 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2376 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2377
2378 if (active_gc_threads > 1) {
2379 for (uint j = 0; j < active_gc_threads; j++) {
2380 q->enqueue(new StealMarkingTask(&terminator));
2381 }
2382 }
2383
2384 gc_task_manager()->execute_and_wait(q);
2385 }
2386
2387 // Process reference objects found during marking
2388 {
2389 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2390
2391 ReferenceProcessorStats stats;
2392 if (ref_processor()->processing_is_mt()) {
2393 RefProcTaskExecutor task_executor;
2394 stats = ref_processor()->process_discovered_references(
2395 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2396 &task_executor, &_gc_timer, _gc_tracer.gc_id());
2397 } else {
2398 stats = ref_processor()->process_discovered_references(
2399 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2400 &_gc_timer, _gc_tracer.gc_id());
2401 }
2402
2403 gc_tracer->report_gc_reference_stats(stats);
2404 }
2405
2406 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2407
2408 // This is the point where the entire marking should have completed.
2409 assert(cm->marking_stacks_empty(), "Marking should have completed");
2410
2411 // Follow system dictionary roots and unload classes.
2412 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2413
2414 // Unload nmethods.
2415 CodeCache::do_unloading(is_alive_closure(), purged_class);
2416
2417 // Prune dead klasses from subklass/sibling/implementor lists.
2418 Klass::clean_weak_klass_links(is_alive_closure());
2419
2420 // Delete entries for dead interned strings.
2421 StringTable::unlink(is_alive_closure());
2422
2423 // Clean up unreferenced symbols in symbol table.
2424 SymbolTable::unlink();
2425 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2426 }
2427
2428 void PSParallelCompact::follow_class_loader(ParCompactionManager* cm,
2429 ClassLoaderData* cld) {
2430 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2431 PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure);
2432
2433 cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true);
2434 }
2435
2436 // This should be moved to the shared markSweep code!
2437 class PSAlwaysTrueClosure: public BoolObjectClosure {
2438 public:
2439 bool do_object_b(oop p) { return true; }
2440 };
2441 static PSAlwaysTrueClosure always_true;
2442
2443 void PSParallelCompact::adjust_roots() {
2444 // Adjust the pointers to reflect the new locations
2445 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2446
2447 // Need new claim bits when tracing through and adjusting pointers.
2448 ClassLoaderDataGraph::clear_claimed_marks();
2449
2450 // General strong roots.
2451 Universe::oops_do(adjust_pointer_closure());
2452 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
2453 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2454 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2455 ObjectSynchronizer::oops_do(adjust_pointer_closure());
2456 FlatProfiler::oops_do(adjust_pointer_closure());
2457 Management::oops_do(adjust_pointer_closure());
2458 JvmtiExport::oops_do(adjust_pointer_closure());
2459 SystemDictionary::oops_do(adjust_pointer_closure());
2460 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2461
2462 // Now adjust pointers in remaining weak roots. (All of which should
2463 // have been cleared if they pointed to non-surviving objects.)
2464 // Global (weak) JNI handles
2465 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2466
2467 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
2468 CodeCache::blobs_do(&adjust_from_blobs);
2469 StringTable::oops_do(adjust_pointer_closure());
2470 ref_processor()->weak_oops_do(adjust_pointer_closure());
2471 // Roots were visited so references into the young gen in roots
2472 // may have been scanned. Process them also.
2473 // Should the reference processor have a span that excludes
2474 // young gen objects?
2475 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2476 }
2477
2478 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2479 uint parallel_gc_threads)
2480 {
2481 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2482
2483 // Find the threads that are active
2484 unsigned int which = 0;
2485
2486 const uint task_count = MAX2(parallel_gc_threads, 1U);
2487 for (uint j = 0; j < task_count; j++) {
2488 q->enqueue(new DrainStacksCompactionTask(j));
2489 ParCompactionManager::verify_region_list_empty(j);
2490 // Set the region stacks variables to "no" region stack values
2491 // so that they will be recognized and needing a region stack
2492 // in the stealing tasks if they do not get one by executing
2493 // a draining stack.
2494 ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2495 cm->set_region_stack(NULL);
2496 cm->set_region_stack_index((uint)max_uintx);
2497 }
2498 ParCompactionManager::reset_recycled_stack_index();
2499
2500 // Find all regions that are available (can be filled immediately) and
2501 // distribute them to the thread stacks. The iteration is done in reverse
2502 // order (high to low) so the regions will be removed in ascending order.
2503
2504 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2505
2506 size_t fillable_regions = 0; // A count for diagnostic purposes.
2507 // A region index which corresponds to the tasks created above.
2508 // "which" must be 0 <= which < task_count
2509
2510 which = 0;
2511 // id + 1 is used to test termination so unsigned can
2512 // be used with an old_space_id == 0.
2513 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2514 SpaceInfo* const space_info = _space_info + id;
2515 MutableSpace* const space = space_info->space();
2516 HeapWord* const new_top = space_info->new_top();
2517
2518 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2519 const size_t end_region =
2520 sd.addr_to_region_idx(sd.region_align_up(new_top));
2521
2522 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2523 if (sd.region(cur)->claim_unsafe()) {
2524 ParCompactionManager::region_list_push(which, cur);
2525
2526 if (TraceParallelOldGCCompactionPhase && Verbose) {
2527 const size_t count_mod_8 = fillable_regions & 7;
2528 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2529 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2530 if (count_mod_8 == 7) gclog_or_tty->cr();
2531 }
2532
2533 NOT_PRODUCT(++fillable_regions;)
2534
2535 // Assign regions to tasks in round-robin fashion.
2536 if (++which == task_count) {
2537 assert(which <= parallel_gc_threads,
2538 "Inconsistent number of workers");
2539 which = 0;
2540 }
2541 }
2542 }
2543 }
2544
2545 if (TraceParallelOldGCCompactionPhase) {
2546 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2547 gclog_or_tty->print_cr(SIZE_FORMAT " initially fillable regions", fillable_regions);
2548 }
2549 }
2550
2551 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2552
2553 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2554 uint parallel_gc_threads) {
2555 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2556
2557 ParallelCompactData& sd = PSParallelCompact::summary_data();
2558
2559 // Iterate over all the spaces adding tasks for updating
2560 // regions in the dense prefix. Assume that 1 gc thread
2561 // will work on opening the gaps and the remaining gc threads
2562 // will work on the dense prefix.
2563 unsigned int space_id;
2564 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2565 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2566 const MutableSpace* const space = _space_info[space_id].space();
2567
2568 if (dense_prefix_end == space->bottom()) {
2569 // There is no dense prefix for this space.
2570 continue;
2571 }
2572
2573 // The dense prefix is before this region.
2574 size_t region_index_end_dense_prefix =
2575 sd.addr_to_region_idx(dense_prefix_end);
2576 RegionData* const dense_prefix_cp =
2577 sd.region(region_index_end_dense_prefix);
2578 assert(dense_prefix_end == space->end() ||
2579 dense_prefix_cp->available() ||
2580 dense_prefix_cp->claimed(),
2581 "The region after the dense prefix should always be ready to fill");
2582
2583 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2584
2585 // Is there dense prefix work?
2586 size_t total_dense_prefix_regions =
2587 region_index_end_dense_prefix - region_index_start;
2588 // How many regions of the dense prefix should be given to
2589 // each thread?
2590 if (total_dense_prefix_regions > 0) {
2591 uint tasks_for_dense_prefix = 1;
2592 if (total_dense_prefix_regions <=
2593 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2594 // Don't over partition. This assumes that
2595 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2596 // so there are not many regions to process.
2597 tasks_for_dense_prefix = parallel_gc_threads;
2598 } else {
2599 // Over partition
2600 tasks_for_dense_prefix = parallel_gc_threads *
2601 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2602 }
2603 size_t regions_per_thread = total_dense_prefix_regions /
2604 tasks_for_dense_prefix;
2605 // Give each thread at least 1 region.
2606 if (regions_per_thread == 0) {
2607 regions_per_thread = 1;
2608 }
2609
2610 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2611 if (region_index_start >= region_index_end_dense_prefix) {
2612 break;
2613 }
2614 // region_index_end is not processed
2615 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2616 region_index_end_dense_prefix);
2617 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2618 region_index_start,
2619 region_index_end));
2620 region_index_start = region_index_end;
2621 }
2622 }
2623 // This gets any part of the dense prefix that did not
2624 // fit evenly.
2625 if (region_index_start < region_index_end_dense_prefix) {
2626 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2627 region_index_start,
2628 region_index_end_dense_prefix));
2629 }
2630 }
2631 }
2632
2633 void PSParallelCompact::enqueue_region_stealing_tasks(
2634 GCTaskQueue* q,
2635 ParallelTaskTerminator* terminator_ptr,
2636 uint parallel_gc_threads) {
2637 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2638
2639 // Once a thread has drained it's stack, it should try to steal regions from
2640 // other threads.
2641 if (parallel_gc_threads > 1) {
2642 for (uint j = 0; j < parallel_gc_threads; j++) {
2643 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2644 }
2645 }
2646 }
2647
2648 #ifdef ASSERT
2649 // Write a histogram of the number of times the block table was filled for a
2650 // region.
2651 void PSParallelCompact::write_block_fill_histogram(outputStream* const out)
2652 {
2653 if (!TraceParallelOldGCCompactionPhase) return;
2654
2655 typedef ParallelCompactData::RegionData rd_t;
2656 ParallelCompactData& sd = summary_data();
2657
2658 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2659 MutableSpace* const spc = _space_info[id].space();
2660 if (spc->bottom() != spc->top()) {
2661 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2662 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2663 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2664
2665 size_t histo[5] = { 0, 0, 0, 0, 0 };
2666 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2667 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2668
2669 for (const rd_t* cur = beg; cur < end; ++cur) {
2670 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2671 }
2672 out->print("%u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2673 for (size_t i = 0; i < histo_len; ++i) {
2674 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2675 histo[i], 100.0 * histo[i] / region_cnt);
2676 }
2677 out->cr();
2678 }
2679 }
2680 }
2681 #endif // #ifdef ASSERT
2682
2683 void PSParallelCompact::compact() {
2684 // trace("5");
2685 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2686
2687 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2688 PSOldGen* old_gen = heap->old_gen();
2689 old_gen->start_array()->reset();
2690 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2691 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2692 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2693 ParallelTaskTerminator terminator(active_gc_threads, qset);
2694
2695 GCTaskQueue* q = GCTaskQueue::create();
2696 enqueue_region_draining_tasks(q, active_gc_threads);
2697 enqueue_dense_prefix_tasks(q, active_gc_threads);
2698 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2699
2700 {
2701 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2702
2703 gc_task_manager()->execute_and_wait(q);
2704
2705 #ifdef ASSERT
2706 // Verify that all regions have been processed before the deferred updates.
2707 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2708 verify_complete(SpaceId(id));
2709 }
2710 #endif
2711 }
2712
2713 {
2714 // Update the deferred objects, if any. Any compaction manager can be used.
2715 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2716 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2717 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2718 update_deferred_objects(cm, SpaceId(id));
2719 }
2720 }
2721
2722 DEBUG_ONLY(write_block_fill_histogram(gclog_or_tty));
2723 }
2724
2725 #ifdef ASSERT
2726 void PSParallelCompact::verify_complete(SpaceId space_id) {
2727 // All Regions between space bottom() to new_top() should be marked as filled
2728 // and all Regions between new_top() and top() should be available (i.e.,
2729 // should have been emptied).
2730 ParallelCompactData& sd = summary_data();
2731 SpaceInfo si = _space_info[space_id];
2732 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2733 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2734 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2735 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2736 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2737
2738 bool issued_a_warning = false;
2739
2740 size_t cur_region;
2741 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2742 const RegionData* const c = sd.region(cur_region);
2743 if (!c->completed()) {
2744 warning("region " SIZE_FORMAT " not filled: "
2745 "destination_count=%u",
2746 cur_region, c->destination_count());
2747 issued_a_warning = true;
2748 }
2749 }
2750
2751 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2752 const RegionData* const c = sd.region(cur_region);
2753 if (!c->available()) {
2754 warning("region " SIZE_FORMAT " not empty: "
2755 "destination_count=%u",
2756 cur_region, c->destination_count());
2757 issued_a_warning = true;
2758 }
2759 }
2760
2761 if (issued_a_warning) {
2762 print_region_ranges();
2763 }
2764 }
2765 #endif // #ifdef ASSERT
2766
2767 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2768 _start_array->allocate_block(addr);
2769 compaction_manager()->update_contents(oop(addr));
2770 }
2771
2772 // Update interior oops in the ranges of regions [beg_region, end_region).
2773 void
2774 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2775 SpaceId space_id,
2776 size_t beg_region,
2777 size_t end_region) {
2778 ParallelCompactData& sd = summary_data();
2779 ParMarkBitMap* const mbm = mark_bitmap();
2780
2781 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2782 HeapWord* const end_addr = sd.region_to_addr(end_region);
2783 assert(beg_region <= end_region, "bad region range");
2784 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2785
2786 #ifdef ASSERT
2787 // Claim the regions to avoid triggering an assert when they are marked as
2788 // filled.
2789 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2790 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2791 }
2792 #endif // #ifdef ASSERT
2793
2794 if (beg_addr != space(space_id)->bottom()) {
2795 // Find the first live object or block of dead space that *starts* in this
2796 // range of regions. If a partial object crosses onto the region, skip it;
2797 // it will be marked for 'deferred update' when the object head is
2798 // processed. If dead space crosses onto the region, it is also skipped; it
2799 // will be filled when the prior region is processed. If neither of those
2800 // apply, the first word in the region is the start of a live object or dead
2801 // space.
2802 assert(beg_addr > space(space_id)->bottom(), "sanity");
2803 const RegionData* const cp = sd.region(beg_region);
2804 if (cp->partial_obj_size() != 0) {
2805 beg_addr = sd.partial_obj_end(beg_region);
2806 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2807 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2808 }
2809 }
2810
2811 if (beg_addr < end_addr) {
2812 // A live object or block of dead space starts in this range of Regions.
2813 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2814
2815 // Create closures and iterate.
2816 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2817 FillClosure fill_closure(cm, space_id);
2818 ParMarkBitMap::IterationStatus status;
2819 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2820 dense_prefix_end);
2821 if (status == ParMarkBitMap::incomplete) {
2822 update_closure.do_addr(update_closure.source());
2823 }
2824 }
2825
2826 // Mark the regions as filled.
2827 RegionData* const beg_cp = sd.region(beg_region);
2828 RegionData* const end_cp = sd.region(end_region);
2829 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2830 cp->set_completed();
2831 }
2832 }
2833
2834 // Return the SpaceId for the space containing addr. If addr is not in the
2835 // heap, last_space_id is returned. In debug mode it expects the address to be
2836 // in the heap and asserts such.
2837 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2838 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2839
2840 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2841 if (_space_info[id].space()->contains(addr)) {
2842 return SpaceId(id);
2843 }
2844 }
2845
2846 assert(false, "no space contains the addr");
2847 return last_space_id;
2848 }
2849
2850 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2851 SpaceId id) {
2852 assert(id < last_space_id, "bad space id");
2853
2854 ParallelCompactData& sd = summary_data();
2855 const SpaceInfo* const space_info = _space_info + id;
2856 ObjectStartArray* const start_array = space_info->start_array();
2857
2858 const MutableSpace* const space = space_info->space();
2859 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2860 HeapWord* const beg_addr = space_info->dense_prefix();
2861 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2862
2863 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2864 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2865 const RegionData* cur_region;
2866 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2867 HeapWord* const addr = cur_region->deferred_obj_addr();
2868 if (addr != NULL) {
2869 if (start_array != NULL) {
2870 start_array->allocate_block(addr);
2871 }
2872 cm->update_contents(oop(addr));
2873 assert(oop(addr)->is_oop_or_null(), err_msg("Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr))));
2874 }
2875 }
2876 }
2877
2878 // Skip over count live words starting from beg, and return the address of the
2879 // next live word. Unless marked, the word corresponding to beg is assumed to
2880 // be dead. Callers must either ensure beg does not correspond to the middle of
2881 // an object, or account for those live words in some other way. Callers must
2882 // also ensure that there are enough live words in the range [beg, end) to skip.
2883 HeapWord*
2884 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2885 {
2886 assert(count > 0, "sanity");
2887
2888 ParMarkBitMap* m = mark_bitmap();
2889 idx_t bits_to_skip = m->words_to_bits(count);
2890 idx_t cur_beg = m->addr_to_bit(beg);
2891 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2892
2893 do {
2894 cur_beg = m->find_obj_beg(cur_beg, search_end);
2895 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2896 const size_t obj_bits = cur_end - cur_beg + 1;
2897 if (obj_bits > bits_to_skip) {
2898 return m->bit_to_addr(cur_beg + bits_to_skip);
2899 }
2900 bits_to_skip -= obj_bits;
2901 cur_beg = cur_end + 1;
2902 } while (bits_to_skip > 0);
2903
2904 // Skipping the desired number of words landed just past the end of an object.
2905 // Find the start of the next object.
2906 cur_beg = m->find_obj_beg(cur_beg, search_end);
2907 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2908 return m->bit_to_addr(cur_beg);
2909 }
2910
2911 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2912 SpaceId src_space_id,
2913 size_t src_region_idx)
2914 {
2915 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2916
2917 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2918 if (split_info.dest_region_addr() == dest_addr) {
2919 // The partial object ending at the split point contains the first word to
2920 // be copied to dest_addr.
2921 return split_info.first_src_addr();
2922 }
2923
2924 const ParallelCompactData& sd = summary_data();
2925 ParMarkBitMap* const bitmap = mark_bitmap();
2926 const size_t RegionSize = ParallelCompactData::RegionSize;
2927
2928 assert(sd.is_region_aligned(dest_addr), "not aligned");
2929 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2930 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2931 HeapWord* const src_region_destination = src_region_ptr->destination();
2932
2933 assert(dest_addr >= src_region_destination, "wrong src region");
2934 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2935
2936 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2937 HeapWord* const src_region_end = src_region_beg + RegionSize;
2938
2939 HeapWord* addr = src_region_beg;
2940 if (dest_addr == src_region_destination) {
2941 // Return the first live word in the source region.
2942 if (partial_obj_size == 0) {
2943 addr = bitmap->find_obj_beg(addr, src_region_end);
2944 assert(addr < src_region_end, "no objects start in src region");
2945 }
2946 return addr;
2947 }
2948
2949 // Must skip some live data.
2950 size_t words_to_skip = dest_addr - src_region_destination;
2951 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2952
2953 if (partial_obj_size >= words_to_skip) {
2954 // All the live words to skip are part of the partial object.
2955 addr += words_to_skip;
2956 if (partial_obj_size == words_to_skip) {
2957 // Find the first live word past the partial object.
2958 addr = bitmap->find_obj_beg(addr, src_region_end);
2959 assert(addr < src_region_end, "wrong src region");
2960 }
2961 return addr;
2962 }
2963
2964 // Skip over the partial object (if any).
2965 if (partial_obj_size != 0) {
2966 words_to_skip -= partial_obj_size;
2967 addr += partial_obj_size;
2968 }
2969
2970 // Skip over live words due to objects that start in the region.
2971 addr = skip_live_words(addr, src_region_end, words_to_skip);
2972 assert(addr < src_region_end, "wrong src region");
2973 return addr;
2974 }
2975
2976 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2977 SpaceId src_space_id,
2978 size_t beg_region,
2979 HeapWord* end_addr)
2980 {
2981 ParallelCompactData& sd = summary_data();
2982
2983 #ifdef ASSERT
2984 MutableSpace* const src_space = _space_info[src_space_id].space();
2985 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2986 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2987 "src_space_id does not match beg_addr");
2988 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2989 "src_space_id does not match end_addr");
2990 #endif // #ifdef ASSERT
2991
2992 RegionData* const beg = sd.region(beg_region);
2993 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2994
2995 // Regions up to new_top() are enqueued if they become available.
2996 HeapWord* const new_top = _space_info[src_space_id].new_top();
2997 RegionData* const enqueue_end =
2998 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2999
3000 for (RegionData* cur = beg; cur < end; ++cur) {
3001 assert(cur->data_size() > 0, "region must have live data");
3002 cur->decrement_destination_count();
3003 if (cur < enqueue_end && cur->available() && cur->claim()) {
3004 cm->push_region(sd.region(cur));
3005 }
3006 }
3007 }
3008
3009 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3010 SpaceId& src_space_id,
3011 HeapWord*& src_space_top,
3012 HeapWord* end_addr)
3013 {
3014 typedef ParallelCompactData::RegionData RegionData;
3015
3016 ParallelCompactData& sd = PSParallelCompact::summary_data();
3017 const size_t region_size = ParallelCompactData::RegionSize;
3018
3019 size_t src_region_idx = 0;
3020
3021 // Skip empty regions (if any) up to the top of the space.
3022 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3023 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3024 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3025 const RegionData* const top_region_ptr =
3026 sd.addr_to_region_ptr(top_aligned_up);
3027 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3028 ++src_region_ptr;
3029 }
3030
3031 if (src_region_ptr < top_region_ptr) {
3032 // The next source region is in the current space. Update src_region_idx
3033 // and the source address to match src_region_ptr.
3034 src_region_idx = sd.region(src_region_ptr);
3035 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3036 if (src_region_addr > closure.source()) {
3037 closure.set_source(src_region_addr);
3038 }
3039 return src_region_idx;
3040 }
3041
3042 // Switch to a new source space and find the first non-empty region.
3043 unsigned int space_id = src_space_id + 1;
3044 assert(space_id < last_space_id, "not enough spaces");
3045
3046 HeapWord* const destination = closure.destination();
3047
3048 do {
3049 MutableSpace* space = _space_info[space_id].space();
3050 HeapWord* const bottom = space->bottom();
3051 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3052
3053 // Iterate over the spaces that do not compact into themselves.
3054 if (bottom_cp->destination() != bottom) {
3055 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3056 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3057
3058 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3059 if (src_cp->live_obj_size() > 0) {
3060 // Found it.
3061 assert(src_cp->destination() == destination,
3062 "first live obj in the space must match the destination");
3063 assert(src_cp->partial_obj_size() == 0,
3064 "a space cannot begin with a partial obj");
3065
3066 src_space_id = SpaceId(space_id);
3067 src_space_top = space->top();
3068 const size_t src_region_idx = sd.region(src_cp);
3069 closure.set_source(sd.region_to_addr(src_region_idx));
3070 return src_region_idx;
3071 } else {
3072 assert(src_cp->data_size() == 0, "sanity");
3073 }
3074 }
3075 }
3076 } while (++space_id < last_space_id);
3077
3078 assert(false, "no source region was found");
3079 return 0;
3080 }
3081
3082 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3083 {
3084 typedef ParMarkBitMap::IterationStatus IterationStatus;
3085 const size_t RegionSize = ParallelCompactData::RegionSize;
3086 ParMarkBitMap* const bitmap = mark_bitmap();
3087 ParallelCompactData& sd = summary_data();
3088 RegionData* const region_ptr = sd.region(region_idx);
3089
3090 // Get the items needed to construct the closure.
3091 HeapWord* dest_addr = sd.region_to_addr(region_idx);
3092 SpaceId dest_space_id = space_id(dest_addr);
3093 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3094 HeapWord* new_top = _space_info[dest_space_id].new_top();
3095 assert(dest_addr < new_top, "sanity");
3096 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3097
3098 // Get the source region and related info.
3099 size_t src_region_idx = region_ptr->source_region();
3100 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3101 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3102
3103 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3104 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3105
3106 // Adjust src_region_idx to prepare for decrementing destination counts (the
3107 // destination count is not decremented when a region is copied to itself).
3108 if (src_region_idx == region_idx) {
3109 src_region_idx += 1;
3110 }
3111
3112 if (bitmap->is_unmarked(closure.source())) {
3113 // The first source word is in the middle of an object; copy the remainder
3114 // of the object or as much as will fit. The fact that pointer updates were
3115 // deferred will be noted when the object header is processed.
3116 HeapWord* const old_src_addr = closure.source();
3117 closure.copy_partial_obj();
3118 if (closure.is_full()) {
3119 decrement_destination_counts(cm, src_space_id, src_region_idx,
3120 closure.source());
3121 region_ptr->set_deferred_obj_addr(NULL);
3122 region_ptr->set_completed();
3123 return;
3124 }
3125
3126 HeapWord* const end_addr = sd.region_align_down(closure.source());
3127 if (sd.region_align_down(old_src_addr) != end_addr) {
3128 // The partial object was copied from more than one source region.
3129 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3130
3131 // Move to the next source region, possibly switching spaces as well. All
3132 // args except end_addr may be modified.
3133 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3134 end_addr);
3135 }
3136 }
3137
3138 do {
3139 HeapWord* const cur_addr = closure.source();
3140 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3141 src_space_top);
3142 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3143
3144 if (status == ParMarkBitMap::incomplete) {
3145 // The last obj that starts in the source region does not end in the
3146 // region.
3147 assert(closure.source() < end_addr, "sanity");
3148 HeapWord* const obj_beg = closure.source();
3149 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3150 src_space_top);
3151 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3152 if (obj_end < range_end) {
3153 // The end was found; the entire object will fit.
3154 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3155 assert(status != ParMarkBitMap::would_overflow, "sanity");
3156 } else {
3157 // The end was not found; the object will not fit.
3158 assert(range_end < src_space_top, "obj cannot cross space boundary");
3159 status = ParMarkBitMap::would_overflow;
3160 }
3161 }
3162
3163 if (status == ParMarkBitMap::would_overflow) {
3164 // The last object did not fit. Note that interior oop updates were
3165 // deferred, then copy enough of the object to fill the region.
3166 region_ptr->set_deferred_obj_addr(closure.destination());
3167 status = closure.copy_until_full(); // copies from closure.source()
3168
3169 decrement_destination_counts(cm, src_space_id, src_region_idx,
3170 closure.source());
3171 region_ptr->set_completed();
3172 return;
3173 }
3174
3175 if (status == ParMarkBitMap::full) {
3176 decrement_destination_counts(cm, src_space_id, src_region_idx,
3177 closure.source());
3178 region_ptr->set_deferred_obj_addr(NULL);
3179 region_ptr->set_completed();
3180 return;
3181 }
3182
3183 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3184
3185 // Move to the next source region, possibly switching spaces as well. All
3186 // args except end_addr may be modified.
3187 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3188 end_addr);
3189 } while (true);
3190 }
3191
3192 void PSParallelCompact::fill_blocks(size_t region_idx)
3193 {
3194 // Fill in the block table elements for the specified region. Each block
3195 // table element holds the number of live words in the region that are to the
3196 // left of the first object that starts in the block. Thus only blocks in
3197 // which an object starts need to be filled.
3198 //
3199 // The algorithm scans the section of the bitmap that corresponds to the
3200 // region, keeping a running total of the live words. When an object start is
3201 // found, if it's the first to start in the block that contains it, the
3202 // current total is written to the block table element.
3203 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
3204 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
3205 const size_t RegionSize = ParallelCompactData::RegionSize;
3206
3207 ParallelCompactData& sd = summary_data();
3208 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
3209 if (partial_obj_size >= RegionSize) {
3210 return; // No objects start in this region.
3211 }
3212
3213 // Ensure the first loop iteration decides that the block has changed.
3214 size_t cur_block = sd.block_count();
3215
3216 const ParMarkBitMap* const bitmap = mark_bitmap();
3217
3218 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
3219 assert((size_t)1 << Log2BitsPerBlock ==
3220 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
3221
3222 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
3223 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
3224 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
3225 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
3226 while (beg_bit < range_end) {
3227 const size_t new_block = beg_bit >> Log2BitsPerBlock;
3228 if (new_block != cur_block) {
3229 cur_block = new_block;
3230 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
3231 }
3232
3233 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
3234 if (end_bit < range_end - 1) {
3235 live_bits += end_bit - beg_bit + 1;
3236 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
3237 } else {
3238 return;
3239 }
3240 }
3241 }
3242
3243 void
3244 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3245 const MutableSpace* sp = space(space_id);
3246 if (sp->is_empty()) {
3247 return;
3248 }
3249
3250 ParallelCompactData& sd = PSParallelCompact::summary_data();
3251 ParMarkBitMap* const bitmap = mark_bitmap();
3252 HeapWord* const dp_addr = dense_prefix(space_id);
3253 HeapWord* beg_addr = sp->bottom();
3254 HeapWord* end_addr = sp->top();
3255
3256 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3257
3258 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3259 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3260 if (beg_region < dp_region) {
3261 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3262 }
3263
3264 // The destination of the first live object that starts in the region is one
3265 // past the end of the partial object entering the region (if any).
3266 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3267 HeapWord* const new_top = _space_info[space_id].new_top();
3268 assert(new_top >= dest_addr, "bad new_top value");
3269 const size_t words = pointer_delta(new_top, dest_addr);
3270
3271 if (words > 0) {
3272 ObjectStartArray* start_array = _space_info[space_id].start_array();
3273 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3274
3275 ParMarkBitMap::IterationStatus status;
3276 status = bitmap->iterate(&closure, dest_addr, end_addr);
3277 assert(status == ParMarkBitMap::full, "iteration not complete");
3278 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3279 "live objects skipped because closure is full");
3280 }
3281 }
3282
3283 jlong PSParallelCompact::millis_since_last_gc() {
3284 // We need a monotonically non-decreasing time in ms but
3285 // os::javaTimeMillis() does not guarantee monotonicity.
3286 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3287 jlong ret_val = now - _time_of_last_gc;
3288 // XXX See note in genCollectedHeap::millis_since_last_gc().
3289 if (ret_val < 0) {
3290 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
3291 return 0;
3292 }
3293 return ret_val;
3294 }
3295
3296 void PSParallelCompact::reset_millis_since_last_gc() {
3297 // We need a monotonically non-decreasing time in ms but
3298 // os::javaTimeMillis() does not guarantee monotonicity.
3299 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3300 }
3301
3302 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3303 {
3304 if (source() != destination()) {
3305 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3306 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3307 }
3308 update_state(words_remaining());
3309 assert(is_full(), "sanity");
3310 return ParMarkBitMap::full;
3311 }
3312
3313 void MoveAndUpdateClosure::copy_partial_obj()
3314 {
3315 size_t words = words_remaining();
3316
3317 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3318 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3319 if (end_addr < range_end) {
3320 words = bitmap()->obj_size(source(), end_addr);
3321 }
3322
3323 // This test is necessary; if omitted, the pointer updates to a partial object
3324 // that crosses the dense prefix boundary could be overwritten.
3325 if (source() != destination()) {
3326 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3327 Copy::aligned_conjoint_words(source(), destination(), words);
3328 }
3329 update_state(words);
3330 }
3331
3332 void InstanceKlass::oop_pc_update_pointers(oop obj) {
3333 oop_oop_iterate_oop_maps<true>(obj, PSParallelCompact::adjust_pointer_closure());
3334 }
3335
3336 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj) {
3337 InstanceKlass::oop_pc_update_pointers(obj);
3338
3339 oop_oop_iterate_statics<true>(obj, PSParallelCompact::adjust_pointer_closure());
3340 }
3341
3342 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj) {
3343 InstanceKlass::oop_pc_update_pointers(obj);
3344 }
3345
3346 #ifdef ASSERT
3347 template <class T> static void trace_reference_gc(const char *s, oop obj,
3348 T* referent_addr,
3349 T* next_addr,
3350 T* discovered_addr) {
3351 if(TraceReferenceGC && PrintGCDetails) {
3352 gclog_or_tty->print_cr("%s obj " PTR_FORMAT, s, p2i(obj));
3353 gclog_or_tty->print_cr(" referent_addr/* " PTR_FORMAT " / "
3354 PTR_FORMAT, p2i(referent_addr),
3355 referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3356 gclog_or_tty->print_cr(" next_addr/* " PTR_FORMAT " / "
3357 PTR_FORMAT, p2i(next_addr),
3358 next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3359 gclog_or_tty->print_cr(" discovered_addr/* " PTR_FORMAT " / "
3360 PTR_FORMAT, p2i(discovered_addr),
3361 discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3362 }
3363 }
3364 #endif
3365
3366 template <class T>
3367 static void oop_pc_update_pointers_specialized(oop obj) {
3368 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3369 PSParallelCompact::adjust_pointer(referent_addr);
3370 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3371 PSParallelCompact::adjust_pointer(next_addr);
3372 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3373 PSParallelCompact::adjust_pointer(discovered_addr);
3374 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3375 referent_addr, next_addr, discovered_addr);)
3376 }
3377
3378 void InstanceRefKlass::oop_pc_update_pointers(oop obj) {
3379 InstanceKlass::oop_pc_update_pointers(obj);
3380
3381 if (UseCompressedOops) {
3382 oop_pc_update_pointers_specialized<narrowOop>(obj);
3383 } else {
3384 oop_pc_update_pointers_specialized<oop>(obj);
3385 }
3386 }
3387
3388 void ObjArrayKlass::oop_pc_update_pointers(oop obj) {
3389 assert(obj->is_objArray(), "obj must be obj array");
3390 oop_oop_iterate_elements<true>(objArrayOop(obj), PSParallelCompact::adjust_pointer_closure());
3391 }
3392
3393 void TypeArrayKlass::oop_pc_update_pointers(oop obj) {
3394 assert(obj->is_typeArray(),"must be a type array");
3395 }
3396
3397 ParMarkBitMapClosure::IterationStatus
3398 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3399 assert(destination() != NULL, "sanity");
3400 assert(bitmap()->obj_size(addr) == words, "bad size");
3401
3402 _source = addr;
3403 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3404 destination(), "wrong destination");
3405
3406 if (words > words_remaining()) {
3407 return ParMarkBitMap::would_overflow;
3408 }
3409
3410 // The start_array must be updated even if the object is not moving.
3411 if (_start_array != NULL) {
3412 _start_array->allocate_block(destination());
3413 }
3414
3415 if (destination() != source()) {
3416 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3417 Copy::aligned_conjoint_words(source(), destination(), words);
3418 }
3419
3420 oop moved_oop = (oop) destination();
3421 compaction_manager()->update_contents(moved_oop);
3422 assert(moved_oop->is_oop_or_null(), err_msg("Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop)));
3423
3424 update_state(words);
3425 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3426 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3427 }
3428
3429 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3430 ParCompactionManager* cm,
3431 PSParallelCompact::SpaceId space_id) :
3432 ParMarkBitMapClosure(mbm, cm),
3433 _space_id(space_id),
3434 _start_array(PSParallelCompact::start_array(space_id))
3435 {
3436 }
3437
3438 // Updates the references in the object to their new values.
3439 ParMarkBitMapClosure::IterationStatus
3440 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3441 do_addr(addr);
3442 return ParMarkBitMap::incomplete;
3443 }