1 /*
2 * Copyright (c) 2018, 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 #include "precompiled.hpp"
25
26 #include "logging/log.hpp"
27 #include "logging/logStream.hpp"
28 #include "memory/binaryTreeDictionary.inline.hpp"
29 #include "memory/freeList.inline.hpp"
30 #include "memory/metaspace/chunkManager.hpp"
31 #include "memory/metaspace/metachunk.hpp"
32 #include "memory/metaspace/metaspaceCommon.hpp"
33 #include "memory/metaspace/metaspaceStatistics.hpp"
34 #include "memory/metaspace/occupancyMap.hpp"
35 #include "memory/metaspace/virtualSpaceNode.hpp"
36 #include "runtime/mutexLocker.hpp"
37 #include "utilities/debug.hpp"
38 #include "utilities/globalDefinitions.hpp"
39 #include "utilities/ostream.hpp"
40
41 namespace metaspace {
42 namespace internals {
43
44
45 void ChunkManager::remove_chunk(Metachunk* chunk) {
46 size_t word_size = chunk->word_size();
47 ChunkIndex index = list_index(word_size);
48 if (index != HumongousIndex) {
49 free_chunks(index)->remove_chunk(chunk);
50 } else {
51 humongous_dictionary()->remove_chunk(chunk);
52 }
53
54 // Chunk has been removed from the chunks free list, update counters.
55 account_for_removed_chunk(chunk);
56 }
57
58 bool ChunkManager::attempt_to_coalesce_around_chunk(Metachunk* chunk, ChunkIndex target_chunk_type) {
59 assert_lock_strong(MetaspaceExpand_lock);
60 assert(chunk != NULL, "invalid chunk pointer");
61 // Check for valid merge combinations.
62 assert((chunk->get_chunk_type() == SpecializedIndex &&
63 (target_chunk_type == SmallIndex || target_chunk_type == MediumIndex)) ||
64 (chunk->get_chunk_type() == SmallIndex && target_chunk_type == MediumIndex),
65 "Invalid chunk merge combination.");
66
67 const size_t target_chunk_word_size =
68 get_size_for_nonhumongous_chunktype(target_chunk_type, this->is_class());
69
70 // [ prospective merge region )
71 MetaWord* const p_merge_region_start =
72 (MetaWord*) align_down(chunk, target_chunk_word_size * sizeof(MetaWord));
73 MetaWord* const p_merge_region_end =
74 p_merge_region_start + target_chunk_word_size;
75
76 // We need the VirtualSpaceNode containing this chunk and its occupancy map.
77 VirtualSpaceNode* const vsn = chunk->container();
78 OccupancyMap* const ocmap = vsn->occupancy_map();
79
80 // The prospective chunk merge range must be completely contained by the
81 // committed range of the virtual space node.
82 if (p_merge_region_start < vsn->bottom() || p_merge_region_end > vsn->top()) {
83 return false;
84 }
85
86 // Only attempt to merge this range if at its start a chunk starts and at its end
87 // a chunk ends. If a chunk (can only be humongous) straddles either start or end
88 // of that range, we cannot merge.
89 if (!ocmap->chunk_starts_at_address(p_merge_region_start)) {
90 return false;
91 }
92 if (p_merge_region_end < vsn->top() &&
93 !ocmap->chunk_starts_at_address(p_merge_region_end)) {
94 return false;
95 }
96
97 // Now check if the prospective merge area contains live chunks. If it does we cannot merge.
98 if (ocmap->is_region_in_use(p_merge_region_start, target_chunk_word_size)) {
99 return false;
100 }
101
102 // Success! Remove all chunks in this region...
103 log_trace(gc, metaspace, freelist)("%s: coalescing chunks in area [%p-%p)...",
104 (is_class() ? "class space" : "metaspace"),
105 p_merge_region_start, p_merge_region_end);
106
107 const int num_chunks_removed =
108 remove_chunks_in_area(p_merge_region_start, target_chunk_word_size);
109
110 // ... and create a single new bigger chunk.
111 Metachunk* const p_new_chunk =
112 ::new (p_merge_region_start) Metachunk(target_chunk_type, is_class(), target_chunk_word_size, vsn);
113 assert(p_new_chunk == (Metachunk*)p_merge_region_start, "Sanity");
114 p_new_chunk->set_origin(origin_merge);
115
116 log_trace(gc, metaspace, freelist)("%s: created coalesced chunk at %p, size " SIZE_FORMAT_HEX ".",
117 (is_class() ? "class space" : "metaspace"),
118 p_new_chunk, p_new_chunk->word_size() * sizeof(MetaWord));
119
120 // Fix occupancy map: remove old start bits of the small chunks and set new start bit.
121 ocmap->wipe_chunk_start_bits_in_region(p_merge_region_start, target_chunk_word_size);
122 ocmap->set_chunk_starts_at_address(p_merge_region_start, true);
123
124 // Mark chunk as free. Note: it is not necessary to update the occupancy
125 // map in-use map, because the old chunks were also free, so nothing
126 // should have changed.
127 p_new_chunk->set_is_tagged_free(true);
128
129 // Add new chunk to its freelist.
130 ChunkList* const list = free_chunks(target_chunk_type);
131 list->return_chunk_at_head(p_new_chunk);
132
133 // And adjust ChunkManager:: _free_chunks_count (_free_chunks_total
134 // should not have changed, because the size of the space should be the same)
135 _free_chunks_count -= num_chunks_removed;
136 _free_chunks_count ++;
137
138 // VirtualSpaceNode::container_count does not have to be modified:
139 // it means "number of active (non-free) chunks", so merging free chunks
140 // should not affect that count.
141
142 // At the end of a chunk merge, run verification tests.
143 if (VerifyMetaspace) {
144 DEBUG_ONLY(this->locked_verify());
145 DEBUG_ONLY(vsn->verify());
146 }
147
148 return true;
149 }
150
151 // Remove all chunks in the given area - the chunks are supposed to be free -
152 // from their corresponding freelists. Mark them as invalid.
153 // - This does not correct the occupancy map.
154 // - This does not adjust the counters in ChunkManager.
155 // - Does not adjust container count counter in containing VirtualSpaceNode
156 // Returns number of chunks removed.
157 int ChunkManager::remove_chunks_in_area(MetaWord* p, size_t word_size) {
158 assert(p != NULL && word_size > 0, "Invalid range.");
159 const size_t smallest_chunk_size = get_size_for_nonhumongous_chunktype(SpecializedIndex, is_class());
160 assert_is_aligned(word_size, smallest_chunk_size);
161
162 Metachunk* const start = (Metachunk*) p;
163 const Metachunk* const end = (Metachunk*)(p + word_size);
164 Metachunk* cur = start;
165 int num_removed = 0;
166 while (cur < end) {
167 Metachunk* next = (Metachunk*)(((MetaWord*)cur) + cur->word_size());
168 DEBUG_ONLY(do_verify_chunk(cur));
169 assert(cur->get_chunk_type() != HumongousIndex, "Unexpected humongous chunk found at %p.", cur);
170 assert(cur->is_tagged_free(), "Chunk expected to be free (%p)", cur);
171 log_trace(gc, metaspace, freelist)("%s: removing chunk %p, size " SIZE_FORMAT_HEX ".",
172 (is_class() ? "class space" : "metaspace"),
173 cur, cur->word_size() * sizeof(MetaWord));
174 cur->remove_sentinel();
175 // Note: cannot call ChunkManager::remove_chunk, because that
176 // modifies the counters in ChunkManager, which we do not want. So
177 // we call remove_chunk on the freelist directly (see also the
178 // splitting function which does the same).
179 ChunkList* const list = free_chunks(list_index(cur->word_size()));
180 list->remove_chunk(cur);
181 num_removed ++;
182 cur = next;
183 }
184 return num_removed;
185 }
186
187 size_t ChunkManager::free_chunks_total_words() {
188 return _free_chunks_total;
189 }
190
191 size_t ChunkManager::free_chunks_total_bytes() {
192 return free_chunks_total_words() * BytesPerWord;
193 }
194
195 // Update internal accounting after a chunk was added
196 void ChunkManager::account_for_added_chunk(const Metachunk* c) {
197 assert_lock_strong(MetaspaceExpand_lock);
198 _free_chunks_count ++;
199 _free_chunks_total += c->word_size();
200 }
201
202 // Update internal accounting after a chunk was removed
203 void ChunkManager::account_for_removed_chunk(const Metachunk* c) {
204 assert_lock_strong(MetaspaceExpand_lock);
205 assert(_free_chunks_count >= 1,
206 "ChunkManager::_free_chunks_count: about to go negative (" SIZE_FORMAT ").", _free_chunks_count);
207 assert(_free_chunks_total >= c->word_size(),
208 "ChunkManager::_free_chunks_total: about to go negative"
209 "(now: " SIZE_FORMAT ", decrement value: " SIZE_FORMAT ").", _free_chunks_total, c->word_size());
210 _free_chunks_count --;
211 _free_chunks_total -= c->word_size();
212 }
213
214 size_t ChunkManager::free_chunks_count() {
215 #ifdef ASSERT
216 if (!UseConcMarkSweepGC && !MetaspaceExpand_lock->is_locked()) {
217 MutexLockerEx cl(MetaspaceExpand_lock,
218 Mutex::_no_safepoint_check_flag);
219 // This lock is only needed in debug because the verification
220 // of the _free_chunks_totals walks the list of free chunks
221 slow_locked_verify_free_chunks_count();
222 }
223 #endif
224 return _free_chunks_count;
225 }
226
227 ChunkIndex ChunkManager::list_index(size_t size) {
228 return get_chunk_type_by_size(size, is_class());
229 }
230
231 size_t ChunkManager::size_by_index(ChunkIndex index) const {
232 index_bounds_check(index);
233 assert(index != HumongousIndex, "Do not call for humongous chunks.");
234 return get_size_for_nonhumongous_chunktype(index, is_class());
235 }
236
237 void ChunkManager::locked_verify_free_chunks_total() {
238 assert_lock_strong(MetaspaceExpand_lock);
239 assert(sum_free_chunks() == _free_chunks_total,
240 "_free_chunks_total " SIZE_FORMAT " is not the"
241 " same as sum " SIZE_FORMAT, _free_chunks_total,
242 sum_free_chunks());
243 }
244
245 void ChunkManager::locked_verify_free_chunks_count() {
246 assert_lock_strong(MetaspaceExpand_lock);
247 assert(sum_free_chunks_count() == _free_chunks_count,
248 "_free_chunks_count " SIZE_FORMAT " is not the"
249 " same as sum " SIZE_FORMAT, _free_chunks_count,
250 sum_free_chunks_count());
251 }
252
253 void ChunkManager::verify() {
254 MutexLockerEx cl(MetaspaceExpand_lock,
255 Mutex::_no_safepoint_check_flag);
256 locked_verify();
257 }
258
259 void ChunkManager::locked_verify() {
260 locked_verify_free_chunks_count();
261 locked_verify_free_chunks_total();
262 for (ChunkIndex i = ZeroIndex; i < NumberOfFreeLists; i = next_chunk_index(i)) {
263 ChunkList* list = free_chunks(i);
264 if (list != NULL) {
265 Metachunk* chunk = list->head();
266 while (chunk) {
267 DEBUG_ONLY(do_verify_chunk(chunk);)
268 assert(chunk->is_tagged_free(), "Chunk should be tagged as free.");
269 chunk = chunk->next();
270 }
271 }
272 }
273 }
274
275 void ChunkManager::locked_print_free_chunks(outputStream* st) {
276 assert_lock_strong(MetaspaceExpand_lock);
277 st->print_cr("Free chunk total " SIZE_FORMAT " count " SIZE_FORMAT,
278 _free_chunks_total, _free_chunks_count);
279 }
280
281 void ChunkManager::locked_print_sum_free_chunks(outputStream* st) {
282 assert_lock_strong(MetaspaceExpand_lock);
283 st->print_cr("Sum free chunk total " SIZE_FORMAT " count " SIZE_FORMAT,
284 sum_free_chunks(), sum_free_chunks_count());
285 }
286
287 ChunkList* ChunkManager::free_chunks(ChunkIndex index) {
288 assert(index == SpecializedIndex || index == SmallIndex || index == MediumIndex,
289 "Bad index: %d", (int)index);
290
291 return &_free_chunks[index];
292 }
293
294 // These methods that sum the free chunk lists are used in printing
295 // methods that are used in product builds.
296 size_t ChunkManager::sum_free_chunks() {
297 assert_lock_strong(MetaspaceExpand_lock);
298 size_t result = 0;
299 for (ChunkIndex i = ZeroIndex; i < NumberOfFreeLists; i = next_chunk_index(i)) {
300 ChunkList* list = free_chunks(i);
301
302 if (list == NULL) {
303 continue;
304 }
305
306 result = result + list->count() * list->size();
307 }
308 result = result + humongous_dictionary()->total_size();
309 return result;
310 }
311
312 size_t ChunkManager::sum_free_chunks_count() {
313 assert_lock_strong(MetaspaceExpand_lock);
314 size_t count = 0;
315 for (ChunkIndex i = ZeroIndex; i < NumberOfFreeLists; i = next_chunk_index(i)) {
316 ChunkList* list = free_chunks(i);
317 if (list == NULL) {
318 continue;
319 }
320 count = count + list->count();
321 }
322 count = count + humongous_dictionary()->total_free_blocks();
323 return count;
324 }
325
326 ChunkList* ChunkManager::find_free_chunks_list(size_t word_size) {
327 ChunkIndex index = list_index(word_size);
328 assert(index < HumongousIndex, "No humongous list");
329 return free_chunks(index);
330 }
331
332 // Helper for chunk splitting: given a target chunk size and a larger free chunk,
333 // split up the larger chunk into n smaller chunks, at least one of which should be
334 // the target chunk of target chunk size. The smaller chunks, including the target
335 // chunk, are returned to the freelist. The pointer to the target chunk is returned.
336 // Note that this chunk is supposed to be removed from the freelist right away.
337 Metachunk* ChunkManager::split_chunk(size_t target_chunk_word_size, Metachunk* larger_chunk) {
338 assert(larger_chunk->word_size() > target_chunk_word_size, "Sanity");
339
340 const ChunkIndex larger_chunk_index = larger_chunk->get_chunk_type();
341 const ChunkIndex target_chunk_index = get_chunk_type_by_size(target_chunk_word_size, is_class());
342
343 MetaWord* const region_start = (MetaWord*)larger_chunk;
344 const size_t region_word_len = larger_chunk->word_size();
345 MetaWord* const region_end = region_start + region_word_len;
346 VirtualSpaceNode* const vsn = larger_chunk->container();
347 OccupancyMap* const ocmap = vsn->occupancy_map();
348
349 // Any larger non-humongous chunk size is a multiple of any smaller chunk size.
350 // Since non-humongous chunks are aligned to their chunk size, the larger chunk should start
351 // at an address suitable to place the smaller target chunk.
352 assert_is_aligned(region_start, target_chunk_word_size);
353
354 // Remove old chunk.
355 free_chunks(larger_chunk_index)->remove_chunk(larger_chunk);
356 larger_chunk->remove_sentinel();
357
358 // Prevent access to the old chunk from here on.
359 larger_chunk = NULL;
360 // ... and wipe it.
361 DEBUG_ONLY(memset(region_start, 0xfe, region_word_len * BytesPerWord));
362
363 // In its place create first the target chunk...
364 MetaWord* p = region_start;
365 Metachunk* target_chunk = ::new (p) Metachunk(target_chunk_index, is_class(), target_chunk_word_size, vsn);
366 assert(target_chunk == (Metachunk*)p, "Sanity");
367 target_chunk->set_origin(origin_split);
368
369 // Note: we do not need to mark its start in the occupancy map
370 // because it coincides with the old chunk start.
371
372 // Mark chunk as free and return to the freelist.
373 do_update_in_use_info_for_chunk(target_chunk, false);
374 free_chunks(target_chunk_index)->return_chunk_at_head(target_chunk);
375
376 // This chunk should now be valid and can be verified.
377 DEBUG_ONLY(do_verify_chunk(target_chunk));
378
379 // In the remaining space create the remainder chunks.
380 p += target_chunk->word_size();
381 assert(p < region_end, "Sanity");
382
383 while (p < region_end) {
384
385 // Find the largest chunk size which fits the alignment requirements at address p.
386 ChunkIndex this_chunk_index = prev_chunk_index(larger_chunk_index);
387 size_t this_chunk_word_size = 0;
388 for(;;) {
389 this_chunk_word_size = get_size_for_nonhumongous_chunktype(this_chunk_index, is_class());
390 if (is_aligned(p, this_chunk_word_size * BytesPerWord)) {
391 break;
392 } else {
393 this_chunk_index = prev_chunk_index(this_chunk_index);
394 assert(this_chunk_index >= target_chunk_index, "Sanity");
395 }
396 }
397
398 assert(this_chunk_word_size >= target_chunk_word_size, "Sanity");
399 assert(is_aligned(p, this_chunk_word_size * BytesPerWord), "Sanity");
400 assert(p + this_chunk_word_size <= region_end, "Sanity");
401
402 // Create splitting chunk.
403 Metachunk* this_chunk = ::new (p) Metachunk(this_chunk_index, is_class(), this_chunk_word_size, vsn);
404 assert(this_chunk == (Metachunk*)p, "Sanity");
405 this_chunk->set_origin(origin_split);
406 ocmap->set_chunk_starts_at_address(p, true);
407 do_update_in_use_info_for_chunk(this_chunk, false);
408
409 // This chunk should be valid and can be verified.
410 DEBUG_ONLY(do_verify_chunk(this_chunk));
411
412 // Return this chunk to freelist and correct counter.
413 free_chunks(this_chunk_index)->return_chunk_at_head(this_chunk);
414 _free_chunks_count ++;
415
416 log_trace(gc, metaspace, freelist)("Created chunk at " PTR_FORMAT ", word size "
417 SIZE_FORMAT_HEX " (%s), in split region [" PTR_FORMAT "..." PTR_FORMAT ").",
418 p2i(this_chunk), this_chunk->word_size(), chunk_size_name(this_chunk_index),
419 p2i(region_start), p2i(region_end));
420
421 p += this_chunk_word_size;
422
423 }
424
425 return target_chunk;
426 }
427
428 Metachunk* ChunkManager::free_chunks_get(size_t word_size) {
429 assert_lock_strong(MetaspaceExpand_lock);
430
431 slow_locked_verify();
432
433 Metachunk* chunk = NULL;
434 bool we_did_split_a_chunk = false;
435
436 if (list_index(word_size) != HumongousIndex) {
437
438 ChunkList* free_list = find_free_chunks_list(word_size);
439 assert(free_list != NULL, "Sanity check");
440
441 chunk = free_list->head();
442
443 if (chunk == NULL) {
444 // Split large chunks into smaller chunks if there are no smaller chunks, just large chunks.
445 // This is the counterpart of the coalescing-upon-chunk-return.
446
447 ChunkIndex target_chunk_index = get_chunk_type_by_size(word_size, is_class());
448
449 // Is there a larger chunk we could split?
450 Metachunk* larger_chunk = NULL;
451 ChunkIndex larger_chunk_index = next_chunk_index(target_chunk_index);
452 while (larger_chunk == NULL && larger_chunk_index < NumberOfFreeLists) {
453 larger_chunk = free_chunks(larger_chunk_index)->head();
454 if (larger_chunk == NULL) {
455 larger_chunk_index = next_chunk_index(larger_chunk_index);
456 }
457 }
458
459 if (larger_chunk != NULL) {
460 assert(larger_chunk->word_size() > word_size, "Sanity");
461 assert(larger_chunk->get_chunk_type() == larger_chunk_index, "Sanity");
462
463 // We found a larger chunk. Lets split it up:
464 // - remove old chunk
465 // - in its place, create new smaller chunks, with at least one chunk
466 // being of target size, the others sized as large as possible. This
467 // is to make sure the resulting chunks are "as coalesced as possible"
468 // (similar to VirtualSpaceNode::retire()).
469 // Note: during this operation both ChunkManager and VirtualSpaceNode
470 // are temporarily invalid, so be careful with asserts.
471
472 log_trace(gc, metaspace, freelist)("%s: splitting chunk " PTR_FORMAT
473 ", word size " SIZE_FORMAT_HEX " (%s), to get a chunk of word size " SIZE_FORMAT_HEX " (%s)...",
474 (is_class() ? "class space" : "metaspace"), p2i(larger_chunk), larger_chunk->word_size(),
475 chunk_size_name(larger_chunk_index), word_size, chunk_size_name(target_chunk_index));
476
477 chunk = split_chunk(word_size, larger_chunk);
478
479 // This should have worked.
480 assert(chunk != NULL, "Sanity");
481 assert(chunk->word_size() == word_size, "Sanity");
482 assert(chunk->is_tagged_free(), "Sanity");
483
484 we_did_split_a_chunk = true;
485
486 }
487 }
488
489 if (chunk == NULL) {
490 return NULL;
491 }
492
493 // Remove the chunk as the head of the list.
494 free_list->remove_chunk(chunk);
495
496 log_trace(gc, metaspace, freelist)("ChunkManager::free_chunks_get: free_list: " PTR_FORMAT " chunks left: " SSIZE_FORMAT ".",
497 p2i(free_list), free_list->count());
498
499 } else {
500 chunk = humongous_dictionary()->get_chunk(word_size);
501
502 if (chunk == NULL) {
503 return NULL;
504 }
505
506 log_debug(gc, metaspace, alloc)("Free list allocate humongous chunk size " SIZE_FORMAT " for requested size " SIZE_FORMAT " waste " SIZE_FORMAT,
507 chunk->word_size(), word_size, chunk->word_size() - word_size);
508 }
509
510 // Chunk has been removed from the chunk manager; update counters.
511 account_for_removed_chunk(chunk);
512 do_update_in_use_info_for_chunk(chunk, true);
513 chunk->container()->inc_container_count();
514 chunk->inc_use_count();
515
516 // Remove it from the links to this freelist
517 chunk->set_next(NULL);
518 chunk->set_prev(NULL);
519
520 // Run some verifications (some more if we did a chunk split)
521 #ifdef ASSERT
522 if (VerifyMetaspace) {
523 locked_verify();
524 VirtualSpaceNode* const vsn = chunk->container();
525 vsn->verify();
526 if (we_did_split_a_chunk) {
527 vsn->verify_free_chunks_are_ideally_merged();
528 }
529 }
530 #endif
531
532 return chunk;
533 }
534
535 Metachunk* ChunkManager::chunk_freelist_allocate(size_t word_size) {
536 assert_lock_strong(MetaspaceExpand_lock);
537 slow_locked_verify();
538
539 // Take from the beginning of the list
540 Metachunk* chunk = free_chunks_get(word_size);
541 if (chunk == NULL) {
542 return NULL;
543 }
544
545 assert((word_size <= chunk->word_size()) ||
546 (list_index(chunk->word_size()) == HumongousIndex),
547 "Non-humongous variable sized chunk");
548 LogTarget(Debug, gc, metaspace, freelist) lt;
549 if (lt.is_enabled()) {
550 size_t list_count;
551 if (list_index(word_size) < HumongousIndex) {
552 ChunkList* list = find_free_chunks_list(word_size);
553 list_count = list->count();
554 } else {
555 list_count = humongous_dictionary()->total_count();
556 }
557 LogStream ls(lt);
558 ls.print("ChunkManager::chunk_freelist_allocate: " PTR_FORMAT " chunk " PTR_FORMAT " size " SIZE_FORMAT " count " SIZE_FORMAT " ",
559 p2i(this), p2i(chunk), chunk->word_size(), list_count);
560 ResourceMark rm;
561 locked_print_free_chunks(&ls);
562 }
563
564 return chunk;
565 }
566
567 void ChunkManager::return_single_chunk(Metachunk* chunk) {
568 const ChunkIndex index = chunk->get_chunk_type();
569 assert_lock_strong(MetaspaceExpand_lock);
570 DEBUG_ONLY(do_verify_chunk(chunk);)
571 assert(chunk != NULL, "Expected chunk.");
572 assert(chunk->container() != NULL, "Container should have been set.");
573 assert(chunk->is_tagged_free() == false, "Chunk should be in use.");
574 index_bounds_check(index);
575
576 // Note: mangle *before* returning the chunk to the freelist or dictionary. It does not
577 // matter for the freelist (non-humongous chunks), but the humongous chunk dictionary
578 // keeps tree node pointers in the chunk payload area which mangle will overwrite.
579 DEBUG_ONLY(chunk->mangle(badMetaWordVal);)
580
581 if (index != HumongousIndex) {
582 // Return non-humongous chunk to freelist.
583 ChunkList* list = free_chunks(index);
584 assert(list->size() == chunk->word_size(), "Wrong chunk type.");
585 list->return_chunk_at_head(chunk);
586 log_trace(gc, metaspace, freelist)("returned one %s chunk at " PTR_FORMAT " to freelist.",
587 chunk_size_name(index), p2i(chunk));
588 } else {
589 // Return humongous chunk to dictionary.
590 assert(chunk->word_size() > free_chunks(MediumIndex)->size(), "Wrong chunk type.");
591 assert(chunk->word_size() % free_chunks(SpecializedIndex)->size() == 0,
592 "Humongous chunk has wrong alignment.");
593 _humongous_dictionary.return_chunk(chunk);
594 log_trace(gc, metaspace, freelist)("returned one %s chunk at " PTR_FORMAT " (word size " SIZE_FORMAT ") to freelist.",
595 chunk_size_name(index), p2i(chunk), chunk->word_size());
596 }
597 chunk->container()->dec_container_count();
598 do_update_in_use_info_for_chunk(chunk, false);
599
600 // Chunk has been added; update counters.
601 account_for_added_chunk(chunk);
602
603 // Attempt coalesce returned chunks with its neighboring chunks:
604 // if this chunk is small or special, attempt to coalesce to a medium chunk.
605 if (index == SmallIndex || index == SpecializedIndex) {
606 if (!attempt_to_coalesce_around_chunk(chunk, MediumIndex)) {
607 // This did not work. But if this chunk is special, we still may form a small chunk?
608 if (index == SpecializedIndex) {
609 if (!attempt_to_coalesce_around_chunk(chunk, SmallIndex)) {
610 // give up.
611 }
612 }
613 }
614 }
615
616 }
617
618 void ChunkManager::return_chunk_list(Metachunk* chunks) {
619 if (chunks == NULL) {
620 return;
621 }
622 LogTarget(Trace, gc, metaspace, freelist) log;
623 if (log.is_enabled()) { // tracing
624 log.print("returning list of chunks...");
625 }
626 unsigned num_chunks_returned = 0;
627 size_t size_chunks_returned = 0;
628 Metachunk* cur = chunks;
629 while (cur != NULL) {
630 // Capture the next link before it is changed
631 // by the call to return_chunk_at_head();
632 Metachunk* next = cur->next();
633 if (log.is_enabled()) { // tracing
634 num_chunks_returned ++;
635 size_chunks_returned += cur->word_size();
636 }
637 return_single_chunk(cur);
638 cur = next;
639 }
640 if (log.is_enabled()) { // tracing
641 log.print("returned %u chunks to freelist, total word size " SIZE_FORMAT ".",
642 num_chunks_returned, size_chunks_returned);
643 }
644 }
645
646 void ChunkManager::collect_statistics(ChunkManagerStatistics* out) const {
647 MutexLockerEx cl(MetaspaceExpand_lock, Mutex::_no_safepoint_check_flag);
648 for (ChunkIndex i = ZeroIndex; i < NumberOfInUseLists; i = next_chunk_index(i)) {
649 out->chunk_stats(i).add(num_free_chunks(i), size_free_chunks_in_bytes(i) / sizeof(MetaWord));
650 }
651 }
652
653 } // namespace metaspace
654 } // namespace internals
655
656
657