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
25 #include "precompiled.hpp"
26
27 #include "logging/log.hpp"
28 #include "logging/logStream.hpp"
29 #include "memory/metaspace/metachunk.hpp"
30 #include "memory/metaspace.hpp"
31 #include "memory/metaspace/chunkManager.hpp"
32 #include "memory/metaspace/metaspaceCommon.hpp"
33 #include "memory/metaspace/occupancyMap.hpp"
34 #include "memory/metaspace/virtualSpaceNode.hpp"
35 #include "memory/virtualspace.hpp"
36 #include "runtime/os.hpp"
37 #include "services/memTracker.hpp"
38 #include "utilities/copy.hpp"
39 #include "utilities/debug.hpp"
40 #include "utilities/globalDefinitions.hpp"
41
42 namespace metaspace {
43
44 // Decide if large pages should be committed when the memory is reserved.
45 static bool should_commit_large_pages_when_reserving(size_t bytes) {
46 if (UseLargePages && UseLargePagesInMetaspace && !os::can_commit_large_page_memory()) {
47 size_t words = bytes / BytesPerWord;
48 bool is_class = false; // We never reserve large pages for the class space.
49 if (MetaspaceGC::can_expand(words, is_class) &&
50 MetaspaceGC::allowed_expansion() >= words) {
51 return true;
52 }
53 }
54
55 return false;
56 }
57
58 // byte_size is the size of the associated virtualspace.
59 VirtualSpaceNode::VirtualSpaceNode(bool is_class, size_t bytes) :
60 _is_class(is_class), _top(NULL), _next(NULL), _rs(), _container_count(0), _occupancy_map(NULL) {
61 assert_is_aligned(bytes, Metaspace::reserve_alignment());
62 bool large_pages = should_commit_large_pages_when_reserving(bytes);
63 _rs = ReservedSpace(bytes, Metaspace::reserve_alignment(), large_pages);
64
65 if (_rs.is_reserved()) {
66 assert(_rs.base() != NULL, "Catch if we get a NULL address");
67 assert(_rs.size() != 0, "Catch if we get a 0 size");
68 assert_is_aligned(_rs.base(), Metaspace::reserve_alignment());
69 assert_is_aligned(_rs.size(), Metaspace::reserve_alignment());
70
71 MemTracker::record_virtual_memory_type((address)_rs.base(), mtClass);
72 }
73 }
74
75 void VirtualSpaceNode::purge(ChunkManager* chunk_manager) {
76 DEBUG_ONLY(this->verify();)
77 Metachunk* chunk = first_chunk();
78 Metachunk* invalid_chunk = (Metachunk*) top();
79 while (chunk < invalid_chunk ) {
80 assert(chunk->is_tagged_free(), "Should be tagged free");
81 MetaWord* next = ((MetaWord*)chunk) + chunk->word_size();
82 chunk_manager->remove_chunk(chunk);
83 chunk->remove_sentinel();
84 assert(chunk->next() == NULL &&
85 chunk->prev() == NULL,
86 "Was not removed from its list");
87 chunk = (Metachunk*) next;
88 }
89 }
90
91 void VirtualSpaceNode::print_map(outputStream* st, bool is_class) const {
92
93 if (bottom() == top()) {
94 return;
95 }
96
97 const size_t spec_chunk_size = is_class ? ClassSpecializedChunk : SpecializedChunk;
98 const size_t small_chunk_size = is_class ? ClassSmallChunk : SmallChunk;
99 const size_t med_chunk_size = is_class ? ClassMediumChunk : MediumChunk;
100
101 int line_len = 100;
102 const size_t section_len = align_up(spec_chunk_size * line_len, med_chunk_size);
103 line_len = (int)(section_len / spec_chunk_size);
104
105 static const int NUM_LINES = 4;
106
107 char* lines[NUM_LINES];
108 for (int i = 0; i < NUM_LINES; i ++) {
109 lines[i] = (char*)os::malloc(line_len, mtInternal);
110 }
111 int pos = 0;
112 const MetaWord* p = bottom();
113 const Metachunk* chunk = (const Metachunk*)p;
114 const MetaWord* chunk_end = p + chunk->word_size();
115 while (p < top()) {
116 if (pos == line_len) {
117 pos = 0;
118 for (int i = 0; i < NUM_LINES; i ++) {
119 st->fill_to(22);
120 st->print_raw(lines[i], line_len);
121 st->cr();
122 }
123 }
124 if (pos == 0) {
125 st->print(PTR_FORMAT ":", p2i(p));
126 }
127 if (p == chunk_end) {
128 chunk = (Metachunk*)p;
129 chunk_end = p + chunk->word_size();
130 }
131 // line 1: chunk starting points (a dot if that area is a chunk start).
132 lines[0][pos] = p == (const MetaWord*)chunk ? '.' : ' ';
133
134 // Line 2: chunk type (x=spec, s=small, m=medium, h=humongous), uppercase if
135 // chunk is in use.
136 const bool chunk_is_free = ((Metachunk*)chunk)->is_tagged_free();
137 if (chunk->word_size() == spec_chunk_size) {
138 lines[1][pos] = chunk_is_free ? 'x' : 'X';
139 } else if (chunk->word_size() == small_chunk_size) {
140 lines[1][pos] = chunk_is_free ? 's' : 'S';
141 } else if (chunk->word_size() == med_chunk_size) {
142 lines[1][pos] = chunk_is_free ? 'm' : 'M';
143 } else if (chunk->word_size() > med_chunk_size) {
144 lines[1][pos] = chunk_is_free ? 'h' : 'H';
145 } else {
146 ShouldNotReachHere();
147 }
148
149 // Line 3: chunk origin
150 const ChunkOrigin origin = chunk->get_origin();
151 lines[2][pos] = origin == origin_normal ? ' ' : '0' + (int) origin;
152
153 // Line 4: Virgin chunk? Virgin chunks are chunks created as a byproduct of padding or splitting,
154 // but were never used.
155 lines[3][pos] = chunk->get_use_count() > 0 ? ' ' : 'v';
156
157 p += spec_chunk_size;
158 pos ++;
159 }
160 if (pos > 0) {
161 for (int i = 0; i < NUM_LINES; i ++) {
162 st->fill_to(22);
163 st->print_raw(lines[i], line_len);
164 st->cr();
165 }
166 }
167 for (int i = 0; i < NUM_LINES; i ++) {
168 os::free(lines[i]);
169 }
170 }
171
172
173 #ifdef ASSERT
174 uintx VirtualSpaceNode::container_count_slow() {
175 uintx count = 0;
176 Metachunk* chunk = first_chunk();
177 Metachunk* invalid_chunk = (Metachunk*) top();
178 while (chunk < invalid_chunk ) {
179 MetaWord* next = ((MetaWord*)chunk) + chunk->word_size();
180 do_verify_chunk(chunk);
181 // Don't count the chunks on the free lists. Those are
182 // still part of the VirtualSpaceNode but not currently
183 // counted.
184 if (!chunk->is_tagged_free()) {
185 count++;
186 }
187 chunk = (Metachunk*) next;
188 }
189 return count;
190 }
191 #endif
192
193 #ifdef ASSERT
194 // Verify counters, all chunks in this list node and the occupancy map.
195 void VirtualSpaceNode::verify() {
196 uintx num_in_use_chunks = 0;
197 Metachunk* chunk = first_chunk();
198 Metachunk* invalid_chunk = (Metachunk*) top();
199
200 // Iterate the chunks in this node and verify each chunk.
201 while (chunk < invalid_chunk ) {
202 DEBUG_ONLY(do_verify_chunk(chunk);)
203 if (!chunk->is_tagged_free()) {
204 num_in_use_chunks ++;
205 }
206 MetaWord* next = ((MetaWord*)chunk) + chunk->word_size();
207 chunk = (Metachunk*) next;
208 }
209 assert(_container_count == num_in_use_chunks, "Container count mismatch (real: " UINTX_FORMAT
210 ", counter: " UINTX_FORMAT ".", num_in_use_chunks, _container_count);
211 // Also verify the occupancy map.
212 occupancy_map()->verify(this->bottom(), this->top());
213 }
214 #endif // ASSERT
215
216 #ifdef ASSERT
217 // Verify that all free chunks in this node are ideally merged
218 // (there not should be multiple small chunks where a large chunk could exist.)
219 void VirtualSpaceNode::verify_free_chunks_are_ideally_merged() {
220 Metachunk* chunk = first_chunk();
221 Metachunk* invalid_chunk = (Metachunk*) top();
222 // Shorthands.
223 const size_t size_med = (is_class() ? ClassMediumChunk : MediumChunk) * BytesPerWord;
224 const size_t size_small = (is_class() ? ClassSmallChunk : SmallChunk) * BytesPerWord;
225 int num_free_chunks_since_last_med_boundary = -1;
226 int num_free_chunks_since_last_small_boundary = -1;
227 while (chunk < invalid_chunk ) {
228 // Test for missed chunk merge opportunities: count number of free chunks since last chunk boundary.
229 // Reset the counter when encountering a non-free chunk.
230 if (chunk->get_chunk_type() != HumongousIndex) {
231 if (chunk->is_tagged_free()) {
232 // Count successive free, non-humongous chunks.
233 if (is_aligned(chunk, size_small)) {
234 assert(num_free_chunks_since_last_small_boundary <= 1,
235 "Missed chunk merge opportunity at " PTR_FORMAT " for chunk size " SIZE_FORMAT_HEX ".", p2i(chunk) - size_small, size_small);
236 num_free_chunks_since_last_small_boundary = 0;
237 } else if (num_free_chunks_since_last_small_boundary != -1) {
238 num_free_chunks_since_last_small_boundary ++;
239 }
240 if (is_aligned(chunk, size_med)) {
241 assert(num_free_chunks_since_last_med_boundary <= 1,
242 "Missed chunk merge opportunity at " PTR_FORMAT " for chunk size " SIZE_FORMAT_HEX ".", p2i(chunk) - size_med, size_med);
243 num_free_chunks_since_last_med_boundary = 0;
244 } else if (num_free_chunks_since_last_med_boundary != -1) {
245 num_free_chunks_since_last_med_boundary ++;
246 }
247 } else {
248 // Encountering a non-free chunk, reset counters.
249 num_free_chunks_since_last_med_boundary = -1;
250 num_free_chunks_since_last_small_boundary = -1;
251 }
252 } else {
253 // One cannot merge areas with a humongous chunk in the middle. Reset counters.
254 num_free_chunks_since_last_med_boundary = -1;
255 num_free_chunks_since_last_small_boundary = -1;
256 }
257
258 MetaWord* next = ((MetaWord*)chunk) + chunk->word_size();
259 chunk = (Metachunk*) next;
260 }
261 }
262 #endif // ASSERT
263
264 void VirtualSpaceNode::inc_container_count() {
265 assert_lock_strong(MetaspaceExpand_lock);
266 _container_count++;
267 }
268
269 void VirtualSpaceNode::dec_container_count() {
270 assert_lock_strong(MetaspaceExpand_lock);
271 _container_count--;
272 }
273
274 #ifdef ASSERT
275 void VirtualSpaceNode::verify_container_count() {
276 assert(_container_count == container_count_slow(),
277 "Inconsistency in container_count _container_count " UINTX_FORMAT
278 " container_count_slow() " UINTX_FORMAT, _container_count, container_count_slow());
279 }
280 #endif
281
282 VirtualSpaceNode::~VirtualSpaceNode() {
283 _rs.release();
284 if (_occupancy_map != NULL) {
285 delete _occupancy_map;
286 }
287 #ifdef ASSERT
288 size_t word_size = sizeof(*this) / BytesPerWord;
289 Copy::fill_to_words((HeapWord*) this, word_size, 0xf1f1f1f1);
290 #endif
291 }
292
293 size_t VirtualSpaceNode::used_words_in_vs() const {
294 return pointer_delta(top(), bottom(), sizeof(MetaWord));
295 }
296
297 // Space committed in the VirtualSpace
298 size_t VirtualSpaceNode::capacity_words_in_vs() const {
299 return pointer_delta(end(), bottom(), sizeof(MetaWord));
300 }
301
302 size_t VirtualSpaceNode::free_words_in_vs() const {
303 return pointer_delta(end(), top(), sizeof(MetaWord));
304 }
305
306 // Given an address larger than top(), allocate padding chunks until top is at the given address.
307 void VirtualSpaceNode::allocate_padding_chunks_until_top_is_at(MetaWord* target_top) {
308
309 assert(target_top > top(), "Sanity");
310
311 // Padding chunks are added to the freelist.
312 ChunkManager* const chunk_manager = Metaspace::get_chunk_manager(this->is_class());
313
314 // shorthands
315 const size_t spec_word_size = chunk_manager->specialized_chunk_word_size();
316 const size_t small_word_size = chunk_manager->small_chunk_word_size();
317 const size_t med_word_size = chunk_manager->medium_chunk_word_size();
318
319 while (top() < target_top) {
320
321 // We could make this coding more generic, but right now we only deal with two possible chunk sizes
322 // for padding chunks, so it is not worth it.
323 size_t padding_chunk_word_size = small_word_size;
324 if (is_aligned(top(), small_word_size * sizeof(MetaWord)) == false) {
325 assert_is_aligned(top(), spec_word_size * sizeof(MetaWord)); // Should always hold true.
326 padding_chunk_word_size = spec_word_size;
327 }
328 MetaWord* here = top();
329 assert_is_aligned(here, padding_chunk_word_size * sizeof(MetaWord));
330 inc_top(padding_chunk_word_size);
331
332 // Create new padding chunk.
333 ChunkIndex padding_chunk_type = get_chunk_type_by_size(padding_chunk_word_size, is_class());
334 assert(padding_chunk_type == SpecializedIndex || padding_chunk_type == SmallIndex, "sanity");
335
336 Metachunk* const padding_chunk =
337 ::new (here) Metachunk(padding_chunk_type, is_class(), padding_chunk_word_size, this);
338 assert(padding_chunk == (Metachunk*)here, "Sanity");
339 DEBUG_ONLY(padding_chunk->set_origin(origin_pad);)
340 log_trace(gc, metaspace, freelist)("Created padding chunk in %s at "
341 PTR_FORMAT ", size " SIZE_FORMAT_HEX ".",
342 (is_class() ? "class space " : "metaspace"),
343 p2i(padding_chunk), padding_chunk->word_size() * sizeof(MetaWord));
344
345 // Mark chunk start in occupancy map.
346 occupancy_map()->set_chunk_starts_at_address((MetaWord*)padding_chunk, true);
347
348 // Chunks are born as in-use (see MetaChunk ctor). So, before returning
349 // the padding chunk to its chunk manager, mark it as in use (ChunkManager
350 // will assert that).
351 do_update_in_use_info_for_chunk(padding_chunk, true);
352
353 // Return Chunk to freelist.
354 inc_container_count();
355 chunk_manager->return_single_chunk(padding_chunk);
356 // Please note: at this point, ChunkManager::return_single_chunk()
357 // may already have merged the padding chunk with neighboring chunks, so
358 // it may have vanished at this point. Do not reference the padding
359 // chunk beyond this point.
360 }
361
362 assert(top() == target_top, "Sanity");
363
364 } // allocate_padding_chunks_until_top_is_at()
365
366 // Allocates the chunk from the virtual space only.
367 // This interface is also used internally for debugging. Not all
368 // chunks removed here are necessarily used for allocation.
369 Metachunk* VirtualSpaceNode::take_from_committed(size_t chunk_word_size) {
370 // Non-humongous chunks are to be allocated aligned to their chunk
371 // size. So, start addresses of medium chunks are aligned to medium
372 // chunk size, those of small chunks to small chunk size and so
373 // forth. This facilitates merging of free chunks and reduces
374 // fragmentation. Chunk sizes are spec < small < medium, with each
375 // larger chunk size being a multiple of the next smaller chunk
376 // size.
377 // Because of this alignment, me may need to create a number of padding
378 // chunks. These chunks are created and added to the freelist.
379
380 // The chunk manager to which we will give our padding chunks.
381 ChunkManager* const chunk_manager = Metaspace::get_chunk_manager(this->is_class());
382
383 // shorthands
384 const size_t spec_word_size = chunk_manager->specialized_chunk_word_size();
385 const size_t small_word_size = chunk_manager->small_chunk_word_size();
386 const size_t med_word_size = chunk_manager->medium_chunk_word_size();
387
388 assert(chunk_word_size == spec_word_size || chunk_word_size == small_word_size ||
389 chunk_word_size >= med_word_size, "Invalid chunk size requested.");
390
391 // Chunk alignment (in bytes) == chunk size unless humongous.
392 // Humongous chunks are aligned to the smallest chunk size (spec).
393 const size_t required_chunk_alignment = (chunk_word_size > med_word_size ?
394 spec_word_size : chunk_word_size) * sizeof(MetaWord);
395
396 // Do we have enough space to create the requested chunk plus
397 // any padding chunks needed?
398 MetaWord* const next_aligned =
399 static_cast<MetaWord*>(align_up(top(), required_chunk_alignment));
400 if (!is_available((next_aligned - top()) + chunk_word_size)) {
401 return NULL;
402 }
403
404 // Before allocating the requested chunk, allocate padding chunks if necessary.
405 // We only need to do this for small or medium chunks: specialized chunks are the
406 // smallest size, hence always aligned. Homungous chunks are allocated unaligned
407 // (implicitly, also aligned to smallest chunk size).
408 if ((chunk_word_size == med_word_size || chunk_word_size == small_word_size) && next_aligned > top()) {
409 log_trace(gc, metaspace, freelist)("Creating padding chunks in %s between %p and %p...",
410 (is_class() ? "class space " : "metaspace"),
411 top(), next_aligned);
412 allocate_padding_chunks_until_top_is_at(next_aligned);
413 // Now, top should be aligned correctly.
414 assert_is_aligned(top(), required_chunk_alignment);
415 }
416
417 // Now, top should be aligned correctly.
418 assert_is_aligned(top(), required_chunk_alignment);
419
420 // Bottom of the new chunk
421 MetaWord* chunk_limit = top();
422 assert(chunk_limit != NULL, "Not safe to call this method");
423
424 // The virtual spaces are always expanded by the
425 // commit granularity to enforce the following condition.
426 // Without this the is_available check will not work correctly.
427 assert(_virtual_space.committed_size() == _virtual_space.actual_committed_size(),
428 "The committed memory doesn't match the expanded memory.");
429
430 if (!is_available(chunk_word_size)) {
431 LogTarget(Debug, gc, metaspace, freelist) lt;
432 if (lt.is_enabled()) {
433 LogStream ls(lt);
434 ls.print("VirtualSpaceNode::take_from_committed() not available " SIZE_FORMAT " words ", chunk_word_size);
435 // Dump some information about the virtual space that is nearly full
436 print_on(&ls);
437 }
438 return NULL;
439 }
440
441 // Take the space (bump top on the current virtual space).
442 inc_top(chunk_word_size);
443
444 // Initialize the chunk
445 ChunkIndex chunk_type = get_chunk_type_by_size(chunk_word_size, is_class());
446 Metachunk* result = ::new (chunk_limit) Metachunk(chunk_type, is_class(), chunk_word_size, this);
447 assert(result == (Metachunk*)chunk_limit, "Sanity");
448 occupancy_map()->set_chunk_starts_at_address((MetaWord*)result, true);
449 do_update_in_use_info_for_chunk(result, true);
450
451 inc_container_count();
452
453 if (VerifyMetaspace) {
454 DEBUG_ONLY(chunk_manager->locked_verify());
455 DEBUG_ONLY(this->verify());
456 }
457
458 DEBUG_ONLY(do_verify_chunk(result));
459
460 result->inc_use_count();
461
462 return result;
463 }
464
465
466 // Expand the virtual space (commit more of the reserved space)
467 bool VirtualSpaceNode::expand_by(size_t min_words, size_t preferred_words) {
468 size_t min_bytes = min_words * BytesPerWord;
469 size_t preferred_bytes = preferred_words * BytesPerWord;
470
471 size_t uncommitted = virtual_space()->reserved_size() - virtual_space()->actual_committed_size();
472
473 if (uncommitted < min_bytes) {
474 return false;
475 }
476
477 size_t commit = MIN2(preferred_bytes, uncommitted);
478 bool result = virtual_space()->expand_by(commit, false);
479
480 if (result) {
481 log_trace(gc, metaspace, freelist)("Expanded %s virtual space list node by " SIZE_FORMAT " words.",
482 (is_class() ? "class" : "non-class"), commit);
483 DEBUG_ONLY(Atomic::inc(&g_internal_statistics.num_committed_space_expanded));
484 } else {
485 log_trace(gc, metaspace, freelist)("Failed to expand %s virtual space list node by " SIZE_FORMAT " words.",
486 (is_class() ? "class" : "non-class"), commit);
487 }
488
489 assert(result, "Failed to commit memory");
490
491 return result;
492 }
493
494 Metachunk* VirtualSpaceNode::get_chunk_vs(size_t chunk_word_size) {
495 assert_lock_strong(MetaspaceExpand_lock);
496 Metachunk* result = take_from_committed(chunk_word_size);
497 return result;
498 }
499
500 bool VirtualSpaceNode::initialize() {
501
502 if (!_rs.is_reserved()) {
503 return false;
504 }
505
506 // These are necessary restriction to make sure that the virtual space always
507 // grows in steps of Metaspace::commit_alignment(). If both base and size are
508 // aligned only the middle alignment of the VirtualSpace is used.
509 assert_is_aligned(_rs.base(), Metaspace::commit_alignment());
510 assert_is_aligned(_rs.size(), Metaspace::commit_alignment());
511
512 // ReservedSpaces marked as special will have the entire memory
513 // pre-committed. Setting a committed size will make sure that
514 // committed_size and actual_committed_size agrees.
515 size_t pre_committed_size = _rs.special() ? _rs.size() : 0;
516
517 bool result = virtual_space()->initialize_with_granularity(_rs, pre_committed_size,
518 Metaspace::commit_alignment());
519 if (result) {
520 assert(virtual_space()->committed_size() == virtual_space()->actual_committed_size(),
521 "Checking that the pre-committed memory was registered by the VirtualSpace");
522
523 set_top((MetaWord*)virtual_space()->low());
524 }
525
526 // Initialize Occupancy Map.
527 const size_t smallest_chunk_size = is_class() ? ClassSpecializedChunk : SpecializedChunk;
528 _occupancy_map = new OccupancyMap(bottom(), reserved_words(), smallest_chunk_size);
529
530 return result;
531 }
532
533 void VirtualSpaceNode::print_on(outputStream* st, size_t scale) const {
534 size_t used_words = used_words_in_vs();
535 size_t commit_words = committed_words();
536 size_t res_words = reserved_words();
537 VirtualSpace* vs = virtual_space();
538
539 st->print("node @" PTR_FORMAT ": ", p2i(this));
540 st->print("reserved=");
541 print_scaled_words(st, res_words, scale);
542 st->print(", committed=");
543 print_scaled_words_and_percentage(st, commit_words, res_words, scale);
544 st->print(", used=");
545 print_scaled_words_and_percentage(st, used_words, res_words, scale);
546 st->cr();
547 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", "
548 PTR_FORMAT ", " PTR_FORMAT ")",
549 p2i(bottom()), p2i(top()), p2i(end()),
550 p2i(vs->high_boundary()));
551 }
552
553 #ifdef ASSERT
554 void VirtualSpaceNode::mangle() {
555 size_t word_size = capacity_words_in_vs();
556 Copy::fill_to_words((HeapWord*) low(), word_size, 0xf1f1f1f1);
557 }
558 #endif // ASSERT
559
560 void VirtualSpaceNode::retire(ChunkManager* chunk_manager) {
561 DEBUG_ONLY(verify_container_count();)
562 assert(this->is_class() == chunk_manager->is_class(), "Wrong ChunkManager?");
563 for (int i = (int)MediumIndex; i >= (int)ZeroIndex; --i) {
564 ChunkIndex index = (ChunkIndex)i;
565 size_t chunk_size = chunk_manager->size_by_index(index);
566
567 while (free_words_in_vs() >= chunk_size) {
568 Metachunk* chunk = get_chunk_vs(chunk_size);
569 // Chunk will be allocated aligned, so allocation may require
570 // additional padding chunks. That may cause above allocation to
571 // fail. Just ignore the failed allocation and continue with the
572 // next smaller chunk size. As the VirtualSpaceNode comitted
573 // size should be a multiple of the smallest chunk size, we
574 // should always be able to fill the VirtualSpace completely.
575 if (chunk == NULL) {
576 break;
577 }
578 chunk_manager->return_single_chunk(chunk);
579 }
580 DEBUG_ONLY(verify_container_count();)
581 }
582 assert(free_words_in_vs() == 0, "should be empty now");
583 }
584
585 } // namespace metaspace
586